Wednesday, December 21, 2011

Mechanisms of antibiotic action

Antibiotics target structures and pathways that are unique and important to bacteria such as cell wall synthesis, cytoplasmic membrane synthesis, protein synthesis, nucleic acid (DNA or RNA) synthesis and intermediary metabolism (McCallum, 2010).
A-Inhibition of cell wall synthesis:
Bacterial cell wall function and structure:
A cell wall maintains cellular integrity by countering the effects of osmosis when the cell is in a hypotonic solution. If the wall is disrupted, it no longer prevents the cell from bursting as water moves into the cell by osmosis (Dmitriev et al., 2005).
The major structural component of a bacterial cell wall is its peptidoglycan layer. Peptidoglycan is a huge macromolecule composed of polysaccharide chains of alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) molecules that are cross linked by short peptide chains extending between NAM subunits. To enlarge or divide, a cell must synthesize more peptidoglycan by adding new NAG and NAM subunits to existing NAG-NAM chains, and the new NAM subunits must then be bonded to neighboring NAM subunits (Meroueh et al., 2006).
You need to read more
Manual of Antibiotics: Method of Actions, Mechanisms of Resistance and Relations to Health Care associated Infections

Monday, December 19, 2011


term that is used in microbiology is nanbacteria. Nanobacteria have been claimed in last few years to cause a wide variety of diseases.
Nanobacteria are mineral-forming, sterile-filterable, slow-growing Gram-negative infectious agents [5]. They are detected in bovine/human blood and urine. Nanobacteria-like particles have been detected in synovial fluids of arthritis patients and were shown to gradually increase in number and in size in culture [6].
According to their 16S rDNA structure, nanobacteria belong to the alpha-2 Proteobacteria, subgroup, which includes the Brucella and Bartonella species. Nanobacterium sanguineum (nanobacteria) is the smallest self-replicating organism ever detected—at 50–500 billionths of a meter, 1/1,000th the size of the smallest previously known bacteria [7].
Nanobacteria have been claimed to be associated with a variety of human diseases manifested with pathological calcification. Their most remarkable characteristic is the formation of carbonate apatite crystals of neutral pH and at physiologic phosphate and calcium concentrations. The extracellular mineralization forms a hard protective shelter for these hardy microorganisms and enables them to survive conditions of physical stress that would be lethal to most other bacterial species. Nanobacteria are associated with human kidney stones and psammona bodies in ovarian cancer. Many researchers have thon the potential role these particles may play in the development of urologic pathology, including polycystic kidney disease, renal calculi, and chronic prostatitis. Recent clinical research targeting these agents has proven effective in treating some patients with refractory category III prostatitis [8].
Kidney stones can be debilitating and recur in 50% of patients within 5 years. Kidney stone formation is considered to be a multifactorial disease in which the defense mechanisms and risk factors are imbalanced in favor of stone formation [9].
One theory is that if nanoparticles accumulate in the kidney, they can form the focus of subsequent growth into larger stones over months to years. Other factors, such as physical chemistry and protein inhibitors of crystal growth, also play a role.
Mineral forming nanobacteria are active nidi that attach to, invade, and damage the urinary epithelium of collecting ducts and papilla forming the calcium phosphate center(s) found in most kidney stones. Scientists at NASA have used multiple techniques to determine that nanobacteria infection multiplies faster in space flight simulated conditions than on earth [9].
Nanobacteria are considered to initiate kidney stone formation as they grow faster in a microgravity environment and may explain why astronauts get kidney stones on space missions. This discovery may prove to be critical for future exploratory missions to the moon and Mars. For further proof to this hypothesis, screening of the nanobacterial antigen and antibody level in flight crew before and after flight would be necessary. This concept also opens the door for new diagnostic and therapeutic techniques addressing nanobacterial infection in kidney stones.
Nanoparticles, isolated from renal stones obtained at the time of surgical resection, have been analyzed and propagated in standard cell culture medium [10]. Nanoparticles were isolated from the majority of renal stones. Isolates were sensitive toward selected metabolic inhibitors and antibiotics and contained conserved bacterial proteins and DNA. These findings suggest that renal stone formation is unlikely to be driven solely by physical chemistry; rather, it is critically influenced by specific proteins and cellular responses, and understanding these events will through lights toward new therapeutic targets. Using high-spatial and energy resolution near-edge x-ray absorption fine structure at the 25-nm spatial scale, it is possible to define a biochemical signature for cultured calcified bacteria, including proteins, polysaccharides, nucleic acids, and hydroxyapatite [11].
These preliminary reports suggest that nanoparticles isolated from human samples share spectroscopic characteristics with calcified proteins.
Nanobacteria is claimed to be associated with cardiovascular diserases. Scientists at the Mayo Clinic have examined surgical specimens from patients with cardiovascular pathology to predict the presence of nanobacteria [12]. Analysis of areas with positive immuno staining identified spheres ranging in size from 30 to 100 nm with a spectral pattern of calcium and phosphorus (high-energy dispersive spectroscopy).
Nano-sized particles cultured from calcified but not from non calcified aneurysms were recognized by a DNA-specific dye, incorporated radiolabeled uridine, and after decalcification, appeared via electron microscopy to contain cell walls. Therefore, nanometer-scale particles can be visualized in and cultured from human calcified cardiovascular tissue. In a further study nanoparticles were found near plaque-filled arteries in animal models. The study suggests that nanoparticles potentially represent a previously unrecognized factor in the development of arteriosclerosis and calcific arterial disease [12].

Wednesday, December 14, 2011

Nanotechnology and Advances in Medicine

Nanotechnology is an emerging technology with enormous potential in information and communication technology, biology and biotechnology, medicine and medical technology. Nanotechnology refers to the a new area of science in which systems are designed and manufactured at the scale of the atom, or the nanometer scale. More specifically nanotechnology deals with structures of less than 100 nanometer (nm). One nm is 1 billionth of a meter. there are two approaches in nanotechnology: bottom-up and top-down. The first approach, the bottom-up, involves manipulating small numbers individual atoms or more complex molecules, into structures typically using minute probes. The second, top-down, approach implies controlling processes to force atoms and molecules to build-up themselves to desired locations and/or structures.
Novel nano- and bio-materials, and nano devices are fabricated and controlled by nanotechnology tools and techniques, which investigate and tune the properties, responses and functions of living and non-living matter, at sizes below 100 nm. The potential medical applications are predominantly in detection, diagnostics (disease diagnosis and imaging), monitoring, and therapeutics. The availability of more durable and better prosthetics and new drug-delivery systems are of great scientific interest and give hope for cancer treatment and minimum invasive treatments for heart disease, diabetes and other diseases. Many novel nanoparticles and nanodevices are expected to be used, with an enormous positive impact on human health. The vision is to improve health by enhancing the efficacy and safety of nanosystems and nanodevices.

Sunday, December 11, 2011

Obesity linked to bacteria

Can bacterial flora in gut be linked to obesity? How?Metabolic syndrome is a group of obesity-related metabolic abnormalities that increase an individual’s risk of developing type 2 diabetes and cardiovascular disease. Here, we show that mice genetically deficient in Toll-like receptor 5 (TLR5), a component of the innate immune system that is expressed in the gut mucosa and that helps defend against infection, exhibit hyperphagia and develop hallmark features of metabolic syndrome, including hyperlipidemia, hypertension, insulin resistance, and increased adiposity. These metabolic changes correlated with changes in the composition of the gut microbiota, and transfer of the gut microbiota from TLR5-deficient mice to wild-type germ-free mice conferred many features of metabolic syndrome to the recipients. Food restriction prevented obesity, but not insulin resistance, in the TLR5-deficient mice. These results support the emerging view that the gut microbiota contributes to metabolic disease and suggest that malfunction of the innate immune system may promote the development of metabolic syndrome.
Coated from Published Online March 4 2010
Science 9 April 2010:
Vol. 328 no. 5975 pp. 228-231
DOI: 10.1126/science.1179721
Metabolic Syndrome and Altered Gut Microbiota in Mice Lacking Toll-Like Receptor 5
Matam Vijay-Kumar1, Jesse D. Aitken1, Frederic A. Carvalho1, Tyler C. Cullender2, Simon Mwangi3, Shanthi Srinivasan3, Shanthi V. Sitaraman3, Rob Knight4, Ruth E. Ley2 and Andrew T. Gewirtz1,*


Tuesday, December 6, 2011

Guide for Handling Cytotoxic Drugs-What Health care Should Know?

To ensure all workers are aware of, and understand the risks associated with the handling and
use of cytotoxic drugs and related waste.
Teaching points:
1.1 Risks associated with occupational exposure to cytotoxic drugs and related waste:
• health risks and toxic effects
• reproductive health risks.
1.2 Rationale for use of cytotoxic drug therapy.
1.3 Legislative requirements for the management of cytotoxic hazards, MSDSs, risk assessment, employer
and worker obligations.
1.4 Institutional policies and procedures.
1.5 Definitions; cell replication; drug classifications, pharmacological actions; rationale for use.
Identification of those drugs which are mutagenic, teratogenic and carcinogenic. Cytotoxic drugs as a
class of drugs:
• define ‘carcinogenic’ ‘mutagenic’ and ‘teratogenic’
• concepts of cell replication
• drug classifications and pharmacological action on cellular reproduction.
1.6 Health surveillance for workers working with cytotoxic drugs;
• health assessment of workers after unprotected exposure to cytotoxic drugs:
° rationale
° health assessment required in response to an unprotected exposure
• principles for initial and ongoing health assessment:
° rationale for personnel management
° the purpose of health assessment
° limitations of current health surveillance methods.
1.7 The importance of accurate record keeping (e.g. an activity log, records of spills and penetrating
injuries). Storage requirements for health surveillance documentation to ensure confidentiality,
perpetual safe keeping and retrieval.
1.8 Incidents and spill management
1.9 Safe disposal methods for cytotoxic drugs and related waste. Safe storage, packaging, consigning and
transport of cytotoxic waste:
• the rationale for the identification, segregation and safe handling of cytotoxic waste
• institution policies and procedures as they apply to:
° segregation of cytotoxic waste
° containment of cytotoxic waste
° transport of cytotoxic waste
° management of cytotoxic drug and related waste spills.
1.10 PPE requirements, including, selection, use, fit, maintenance, storage, cleaning and disposal.
To train workers in the safe preparation of cytotoxic drugs.
Teaching points – to include Module 1, plus:
2.1 Facility requirements:
• minimum requirements for a cytotoxic preparation facility as defined by AS 2567-2002:
Laminar flow cytotoxic drug safety cabinets and AS 2639-1994:Laminar flow cytotoxic drug
safety cabinets - Installation and use
106 􀀨􀁖􀁊􀁅􀁆􀀁􀁇􀁐􀁓􀀁􀁉􀁂􀁏􀁅􀁍􀁊􀁏􀁈􀀁􀁄􀁚􀁕􀁐􀁕􀁐􀁙􀁊􀁄􀀁􀁅􀁓􀁖􀁈􀁔􀀁􀁂􀁏􀁅􀀁􀁓􀁆􀁍􀁂􀁕􀁆􀁅􀀁􀁘􀁂􀁔􀁕􀁆􀀁􀀁􀁝􀀁􀀁􀀁􀀸􀁐􀁓􀁌􀁑􀁍􀁂􀁄􀁆􀀁􀀩􀁆􀁂􀁍􀁕􀁉􀀁􀁂􀁏􀁅􀀁􀀴􀁂􀁇􀁆􀁕􀁚􀀁􀀲􀁖􀁆􀁆􀁏􀁔􀁍􀁂􀁏􀁅
• principles of clean spaces, their creation and maintenance as described in AS 1386.1-1989:
Cleanrooms and clean workstations - Principles of clean space control:
° essential elements necessary for the preparation of cytotoxic drugs—clean room, air handling
system, peripheral rooms, cytotoxic dispensing facility (e.g. laminar air flow equipment,
isolators, cytotoxic drugs safety cabinet)
° their function and use
• management of the cytotoxic preparation facility:
° operation of the cytotoxic drugs safety cabinet or isolator
° maintenance of the preparation facility
° approved devices/equipment used in preparing cytotoxic drugs
° management of cytotoxic spills
° management of contaminated waste generated in the preparation of cytotoxic drugs
° preparation records
• certification reports
• activity logs
• pressure differential records
• environmental monitoring.
2.2 Aseptic preparation of a cytotoxic product.
• principles of aseptic preparation of parenteral solutions
• specific requirements for aseptic preparation in cytotoxic drug safety cabinets or isolators.
2.3 Quality assurance measures required for preparation cytotoxic drugs.
2.4 Safe techniques for cytotoxic drugs. Health and safety hazards posed by handling cytotoxic drugs in
powder and liquid form:
• routes of absorption associated with occupational exposure
• hazards involved when cytotoxic drug aerosols are liberated into a workplace.
2.5 Packaging requirements for the safe presentation and receipt of prepared cytotoxic drugs in individual
• labelling and packaging requirements for the presentation of prepared cytotoxic drug doses
• procedure for dealing with broken tablets and capsules
• rationale for the use of primary (e.g. a syringe closure), secondary (e.g. the spill-proof overwrap
containing the syringe) and tertiary (e.g. the spill-proof outer transport container) containers for
the maintenance of product integrity and its safe handling.
2.6 Safe storage and transport of cytotoxic drugs in concentrated from:
• legislative requirements for the storage and transport of cytotoxic drugs
• rationale for specific procedures essential for the storage and transport of cytotoxic drugs
• risks associated with the different presentations of cytotoxic drugs
• institutional policy and procedures as they apply to receipt of goods, storage of goods, transport
of goods, management of cytotoxic drug and related waste spills.
2.7 PPE requirements:
• function and use of PPE—demonstrate appropriate use of PPE:
° selection
° putting on
° concurrent use
• cleaning, laundry and disposal of used PPE.
2.8 Waste management principles of waste containment and segregation:
• contaminated waste disposal
• contaminated patient waste
• cytotoxic waste storage and transport requirements.
2.9 Management in the community.
2.10 Incidents and spill management.
2.11 Record keeping.
To train workers in the safe administration of cytotoxic drugs.
Teaching points - Module 1, plus
3.1 Risks associated with administration for operator and patient:
􀀨􀁖􀁊􀁅􀁆􀀁􀁇􀁐􀁓􀀁􀁉􀁂􀁏􀁅􀁍􀁊􀁏􀁈􀀁􀁄􀁚􀁕􀁐􀁕􀁐􀁙􀁊􀁄􀀁􀁅􀁓􀁖􀁈􀁔􀀁􀁂􀁏􀁅􀀁􀁓􀁆􀁍􀁂􀁕􀁆􀁅􀀁􀁘􀁂􀁔􀁕􀁆􀀁􀀁􀁝􀀁􀀁􀀁􀀸􀁐􀁓􀁌􀁑􀁍􀁂􀁄􀁆􀀁􀀩􀁆􀁂􀁍􀁕􀁉􀀁􀁂􀁏􀁅􀀁􀀴􀁂􀁇􀁆􀁕􀁚􀀁􀀲􀁖􀁆􀁆􀁏􀁔􀁍􀁂􀁏􀁅 107
• physical and chemical characteristics of these drugs as they pertain to occupational safety:
° differences in potential risk between lyophilized drugs, powdered and liquid filled preparations
° substances requiring protective containment
• cytotoxic drugs and their rationale for use:
° cure, control, prophylaxis and palliation
° drug dosages, routes of administration, delivery methods, calculation of body surface area
° cytotoxic drug protocols.
3.2 Principles of safe handling for all routes of administration. Safe administration techniques for
cytotoxic drugs:
• health and safety hazards posed by handling cytotoxic drugs in liquid form:
° routes of absorption associated with occupational exposure
° hazards involved when cytotoxic drug aerosols are liberated into a workplace
• packaging requirements for the safe presentation and receipt of prepared cytotoxic drugs in
individual packing:
° labelling and packaging requirements for the presentation of prepared cytotoxic drug doses
° procedure for dealing with broken tablets and capsules
° rationale for the use of primary (e.g. a syringe closure), secondary (e.g. the spill-proof
overwrap containing the syringe) and tertiary (e.g. the spill-proof outer transport container)
° containers for the maintenance of product integrity and its safe handling
• identifying safe routes of administration—principles of safe handling and administration of
cytotoxic drug injections:
° demonstrate correct and safe use of cytotoxic drug injectables
° identify variety of routes by which cytotoxic drugs are administered
° identify appropriate blood values and assessments prior to drug administration
• principles of safe handling and administration of cytotoxic drug infusions:
° identify appropriate equipment for management of infusions of cytotoxic drugs
° demonstrate correct technique for the connection and disconnection of cytotoxic drug
administration equipment
• principles of safe handling and administration of oral and topical cytotoxic drugs:
° demonstrate no-touch technique in the administration of oral cytotoxic drug doses
° no-touch application technique and drug containment procedures when applying topical
cytotoxic drugs
• reasons for the selection of differing vascular access techniques for parenteral cytotoxic drugs:
° demonstrate techniques of vein access appropriate for intravenous administration of various
cytotoxic agents
• selection of a vascular access site for vesicant and irritant cytotoxic drug administration:
° identify appropriate vascular access site for the cytotoxic drug used
° identify drugs that are vesicants and those that are irritants
• principles of safe handling and administration of intrathecal cytotoxic drugs:
° identify cytotoxic drugs that can be safely administered by intrathecal route
° calculate intrathecal drug doses
° identify risks associated with accidental intrathecal administration of vinca alkaloids
° identify strategies to reduce risk of accidental intrathecal administration of vinca alkaloids,
including transport, packaging, labelling, checking and administration
• safe procedures for the emergency cessation of cytotoxic drug administration (e.g. adverse
reaction), demonstrate systematic approach to the containment of cytotoxic drugs during
emergency cessation
• management of extravasation—identify critical steps for the management of extravasation
• packaging requirements when transporting cytotoxic drugs within the treatment unit:
° principles of package containment for cytotoxic drug transport within the treatment unit
° transport requirements following the addition of needles to prepared syringes.
3.3 PPE requirements—function and use of PPE—demonstrate appropriate use of PPE:
• selection
• putting on
• concurrent use
• cleaning, laundry and disposal of used PPE.
3.4 Safe disposal methods for cytotoxic agents and equipment involved in administration:
principles of waste containment and segregation as applied to cytotoxic drugs
• appropriate containers required for cytotoxic waste disposal
• understand the principles of waste containment and procedures for the disposal of cytotoxic
• procedure for disposal of related cytotoxic drug administration equipment
• safe disposal procedure of PPE.
3.5 Incidents and spill management:
• management of cytotoxic drug spills:
° warning and notification requirements for cytotoxic drug spill management:
- isolation and warning procedures
- remedial action in the event of a spill
- procedure for requesting assistance
° PPE requirements for cytotoxic drug spill management
° principles and procedures for cytotoxic drug spill management:
- equipment necessary to contain the cytotoxic spill
- decontamination solutions or substances for cytotoxic containment
- effective use of cytotoxic spill equipment and decontaminants
- containment and disposal of cytotoxic drug spill materials
° action required when an unprotected exposure to workers occurs (e.g. topical, mucous
membrane, or penetrating injury exposure), identify the appropriate health assessment required
in response to unprotected exposure
° post-spill procedures:
- reporting procedures
- health assessment and follow-up.
3.6 Patient education requirements and ethical considerations.
3.7 Patient handling:
• management of contaminated body substances from patients undergoing and following cytotoxic
drug therapy:
° major pathways of body excretion of unchanged cytotoxic drugs or active drug metabolites
° protective period for safe handing of cytotoxic drug body substances:
- standard excretion times (up to seven days)
- drugs which are excreted over prolonged periods (see appendix 3)
- factors which may delay excretion
° procedures for safe handling of body substances and soiled materials used for patient care:
- use of PPE
- procedures for containment and disposal
- special safety precautions associated with contaminated waste material from catheters,
peritoneal dialysis, colostomies etc.
3.8 Management in the community.
3.9 Record keeping.
3.10 Storage and packaging requirements (for transportation and handling).

CDC recommendations for Post Exposure to Blood Borne Pathogens

• Wounds and skin sites that have been in contact with blood or body fluids should be washed with soap and water; mucous membranes should be flushed with water.
• The person whose blood or body fluid is the source of an occupational exposure should be evaluated for HBV, HCV and HIV infection.
• Post-exposure treatment should begin within 24 hours and not later than 7 days.
• Recommendations for HBV post-exposure management include initiation of the hepatitis B vaccine series to any susceptible, unvaccinated person who sustains an occupational blood or body fluid exposure. Post-exposure prophylaxis (PEP) with hepatitis B immune globulin (HBIG) and/or hepatitis B vaccine series should be considered for occupational exposures after evaluation of the hepatitis B surface antigen status of the source and the vaccination and vaccine-response status of the exposed person.
• There is no post-exposure treatment that will prevent HCV infection. For the person exposed to an HCV-positive source perform baseline testing for anti-HCV and ALT activity; and perform follow-up testing (e.g., at 4–6 months) for anti-HCV and ALT activity (if earlier diagnosis of HCV infection is desired, testing for HCV RNA may be performed at 4–6 weeks). Immune globulin and antiviral agents (e.g., interferon with or without ribavirin) are not recommended for PEP of hepatitis
• Recommendations for HIV PEP include a basic 4-week regimen of two drugs (zidovudine and lamivudine, lamivudine and stavudine or didanosine and stavudine) for most HIV exposures and an expanded regimen that includes the addition of a third drug for HIV exposures that pose an increased risk for transmission.

Escherichia coli

ASM , CDC and FDA ahve put together a report all about E.coli and how it is transmitted. It does not have anything in it about lab testing but it is still a really good resource. Copy and paste this url:http://academy.asm.org/images/stories/documents/EColi.pdf

Prevention of Occupational Health Hazards in Hospitals

Hospital biological hazards elimination:

Elimination of biological hazards includes construction guidelines in hospitals, standard precautions, which must be applied to all patients at all times, additional (transmission-based) precautions which are specific to modes of transmission (airborne, droplet and contact), environmental cleaning, sterilization and disinfection of patient equipment (Manyele et al., 2008).
1. Construction guidelines in hospitals:
An infection control team member should participate on the planning team for any new hospital construction or renovation of existing facilities. The role of infection control in this process is to review and approve construction plans to ensure that they meet standards for minimizing nosocomial infections (Walker et al., 2007).
Considerations will usually include selection of the site of hospitals which should be away from overcrowded public areas especially for hospitals managing infectious diseases as TB, SARS, meningitis and pandemic influenza. Considerations also include proper ventilation, isolation room design, proper traffic flow and appropriate access to hand washing facilities (Lateef, 2009).

a. Ventilation:
Of all the possible engineering techniques that can be employed to control airborne pathogens, good ventilation is probably the most effective. Although most people are familiar with the general concept of ventilation, very few understand the principles on which it is based. The term ventilation should therefore only be applied to the supply of outside air to the room space (Crimi et al., 2005).
Dilution ventilation:
Most ventilation systems push large quantities of ‘clean’ outside air into occupied spaces so that any contaminants in the room space are diluted and flushed out to atmosphere. To function properly good mixing of the air in the room space is essential (McLarnon et al., 2006).
Laminar and displacement ventilation:
This is based mainly on directing airflows to displace the contaminated air so that it is ‘pushed’ out of the room space. In this way the contaminated air is continually being replaced by clean air. With this type of ventilation system it is undesirable to have any air mixing and so ‘laminar’ streams of air are often used. Such ventilation systems are frequently used in operating theatres and isolation rooms (Abdulsalam et al., 2010).

Pressure differences ventilation:
By controlling the airflows within a building it is possible to create ‘high’ and ‘low’ pressure regions. This can be used to great advantage in isolation rooms, which can be negatively pressurized space so that airborne pathogens are unable to escape. These negative pressures can be achieved by supplying less air to an isolation room than is extracted. It is recommended that a positively pressurized anteroom be placed between the corridor and the isolation room according to fire regulations (Crimi et al., 2005).
Natural ventilation:
Many hospital buildings, especially older facilities, rely heavily on natural ventilation. In many ways the natural ventilation of clinical spaces is a good solution. However, reliance solely on natural ventilation has a number of drawbacks such as ventilation rates will be variable and are greatly dependent on the outside climatic conditions. Also, Pathogens such as Aspergillus spp. which is widespread in the outdoor environment can easily enter ward spaces (McLarnon et al., 2006).
b. Room air cleaning devices:
There are a variety of room air cleaning devices currently available, incorporating technologies such as high efficiency particulate air (HEPA) filters and ultraviolet germicidal irradiation (UVGI) lamps. These devices are intended to be mounted within a room space and are designed to reduce the microbial level in the room air. They have the advantage that they are relatively cheap and can be strategically positioned to protect vulnerable patients and staff (Crutis, 2007).

High efficiency particulate air (HEPA) filters units:
HEPA filter units are readily available machines that can be used any where to provide clean air. These units are especially useful in settings that may have inadequate or no ventilation and limited funds for upgrades. HEPA filters exhibit very high efficiencies (i.e. 99.9 % efficient for particles 0.3µm in diameter). HEPA filter unit will provide cleaned air to dilute infectious particles and will also remove airborne particles. HEPA filter units are available in a variety of sizes and configurations. All consist primarily of pre-filter to remove coarser particles and thereby prolong the life of the HEPA filter, a fan to circulate the filtered into the room and controls, such as an on/off switch and fan speed control (Liao et al., 2008).
The most common types of units are portable, free standing and permanent devices. Ceiling-mounted and wall-mounted units are also available. Portable units have the advantage of greater flexibility and ease of installation and service (Eckmanns et al., 2006).
Ultra-violet (UV) germicidal irradiation:
The germicidal properties of UV light have been known about for many years; in the pre-antibiotic era. UV lamps were used extensively in tuberculosis (TB) wards to control the spread of infection, but with the development of anti-bacterial drugs and, in some countries the introduction of vaccination against TB, UV air disinfection fell out of favour. However, in recent years, with the global rise in TB, there has been renewed interest in its use as an infection control measure and several research programmes have been initiated in this field (Kujundzic et al., 2006).
The activation spectrum peaks in the range 260 to 270 nm is similar to the absorption spectrum of nucleic acids, thus deoxyribonucleic acid (DNA) is the main target. UV light at this wave length is absorbed by nucleic acids with the formation of pyrimidine dimers, resulting in damage to the DNA of the micro-organism which is lethal. Conventional low and medium pressure mercury discharge UV lamps have a strong spectral emission at 253.7 nm, close to the peak of the action spectrum and can be used as an effective bactericidal agent (Rudnick and First, 2007).
C. Isolation room design:
The interest in the use of airborne isolation rooms has increased due to the occurrence of new emerging diseases such as severe acute respiratory syndrome (SARS), avian influenza and multi-drug resistant tuberculosis (MDR-TB). The recognition of the possibility of pandemic outbreaks of influenza has required authorities to put in place “emergency planning” for dealing with infected patients that may require isolation (Walker et al., 2007).
Isolation rooms can be used to limit the spread of small-particle aerosols, which may play a role in all isolated diseases. Mechanically ventilated isolation rooms can be classified in to standard, source and protective isolation room according to the ventilation pressure as shown in table (5) (Hoffman et al., 2004).
Isolation rooms which can be switched from one functional type to another such as changing a positive-pressure room into a negative-pressure room are highly hazardous and should be avoided due to the possibility of use at the incorrect pressure regime. If multifunctional facilities are to be used staff must be trained correctly, rooms must have written operating and auditing procedures and in addition electronic warning systems and alerts must be in place (Cheong and Phau, 2006).
Isolation rooms should have minimum air-change rates of 6 air changes an hour (ach) for the protection of staff and visitors in the room. If possible, this should be increased to the 12 ach recommended as a minimum by the American institute of architects. The room airflow pattern should be designed to provide HCWs or visitors with clean air (Lateef, 2009).

d. Traffic flow:
Distinction can be made between high-traffic and low-traffic areas. A hospital with well-defined areas for specific activities can be described using flowcharts depicting the flow of in or outpatients, visitors and staff. Building or rebuilding a hospital requires consideration of all physical movements and communications and where contamination may occur (Manyele et al., 2008).
e. Architectural segregation:
It is useful to stratify patient care areas by risk of the patient population for acquisition of infection. For some units, including oncology, neonatology, intensive care and transplant units special ventilation may be desirable. Four degrees of risk may be considered; low risk areas as the administrative sections, moderate risk areas as the regular patient units, high risk areas including isolation unit and intensive care unit and very high risk areas considering the operating rooms (Tang et al., 2006).
f. Construction material:
The choice of construction material especially those considered in the covering of internal surfaces is very important. Floor coverings must be easy to clean and resistant to disinfection procedures. This also applies to all items in the patient environment (Lateef, 2009).

g. Water supply:
The physical, chemical and bacteriological characteristics of water used in healthcare institutions must meet local regulations. The institution is responsible for the quality of water once it enters the building. For specific uses, water taken from a public network must often be treated for medical use (physical or chemical treatment) (Walkera et al., 2007).
2. Standard precautions for protection of healthcare workers:
These measures must be applied during every patient care and during exposure to any potentially infected material or body fluids as blood and others. These include the following: hand washing and antisepsis (hand hygiene), use of personal protective equipment, appropriate handling of contaminated equipment and prevention of needle stick injuries (Talaat et al., 2003).
1. Hand washing:
Frequent and adequate hand washing is the best way to prevent spread of most nosocomial infections. The extreme importance of hand washing has been known since at least 1847, when Dr Ignaz Semmelweis discovered that washing hands before performing obstetric exams on pregnant women reduced childbirth-related infectious mortality from more than 10% to less than 1% (Jumaa, 2005).
For hand washing the following must be available running water, large washbasins which require little maintenance, with antisplash devices and hands-free controls, products as soap or antiseptic depending on the procedure facilities and disposable towels if possible for hand drying without contamination. For hand disinfection, specific hand disinfectants as alcohol rubs with antiseptic and emollient gels should be present (Naikoba and Hayward, 2001).
Wash of hands must be done after handling any blood, body fluids, secretions, excretions and contaminated items; between contact with different patients; between tasks and procedures on the same patient to prevent cross contamination between different body sites and immediately after removing gloves. Procedures will vary with the patient risk assessment. There are three types of hand wash as shown in the following table (2) (Jumaa, 2005).
2- Barrier precautions (Personal protective equipment):
1. Gloves:
Gloves protect the hands from contacting blood, droplets, body fluids and pathogen-contaminated objects so infection can be prevented when touching the eyes, mouth or nose afterwards. Gloves can also protect open wounds from contamination by pathogen. It is not certain what type of glove provides the best protection for infection control. Some studies have suggested that latex gloves are some what better in preventing penetration of water and virus than vinyl gloves (Wittmann et al., 2010).
2. Masks:
Using the appropriate respiratory protective equipment is important for an adequate protection from biological hazards. Surgical mask is the most common respiratory protective equipment. It should be worn in circumstances where there are likely to be splashes of blood, body fluids, secretions and excretions or when the patient has a communicable disease that is spread via the droplet route (Farrington, 2007).
N95 or higher level respirators filter out particulates and liquid droplets in small particle size, therefore providing protection from inhaling aerosols and micro-organisms that are airborne. N95 masks are used in high-risk wards (Grinshpun et al., 2009).
The mask must fit over the face with the coloured side of the mask faces outwards and the metallic strip upper most, while the strings or elastic bands are positioned properly to keep the mask firmly in place. When the mask is damaged or soiled, it is replaced. (MacIntyre et al., 2009).
If required to wear N-95 mask, the face-piece must be of proper fit. Compare the size of different brands to find a suitable one. To reuse a N95 mask, it should be kept in a paper bag properly before using it again. If the N95 mask is soiled or damaged, it must be replaced immediately. N95 mask should never be shared with any body or brought outside the hospital. N95 masks should not be used by persons suffering from respiratory diseases, such as asthma and emphysema having difficulty in breathing or feeling dizzy after wearing it at this time N95 masks with exhale valve can be used as it lets the hot air out, making the mask more comfortable (Cowling et al., 2009).
3. Protective clothing:
Protective clothing includes protective coverall (with attached hood) and gown should be water proof or impervious to liquids to protect the body from contamination by blood, droplets or other body fluids, thus reducing the chance of spreading of pathogen and cross-infection. Protective clothing is disposable in most cases though some can be reused after sterilization. Standard protective clothing should fit the wearer, checked before use and replaced if damaged. (Northington et al., 2007).
c. Goggles/Face shields:
Safety goggles/glasses and face shields can protect the eyes from contacting pathogen-carrying blood, droplets or other body fluids which may then enter the body through the mucosa. Goggles fit the face snugly and therefore are better than glasses in eye protection. If necessary, face shield should be used to protect the whole face (Davis et al., 2007).

d. Boots/shoe covers:
Boots/shoe covers are used to protect the wearer from splashes of blood, body fluids, secretions and excretions. Waterproof boots should be worn for heavily contaminated, wet flooring and floor cleaning. Shoe covers should be disposable and waterproof (Northington et al., 2007).
e. Caps:
Caps that completely cover the hair are used when splashes of blood and body fluids are expected. They should protect the hair from aerosols that may otherwise lodge on the hair and be transferred to other parts of the healthcare worker such as face or clothing by the hands or onto inanimate objects. Caps should be disposable, waterproof and of an appropriate size which completely covers the hair (Parmeggiani et al., 2010).
3. Sharp precautions:
Needle stick and sharp injuries carry the risk of bloodborne infection e.g AIDS, HCV, HBV and others. Essential elements of the prevention and control of diseases caused by sharp injuries infections include training and education about nature of bloodborne pathogens, activities that place HCW at risk and means to prevent disease transmission as personal protective procedures. Protective procedures are multifaceted and staged. Procedures include the wearing of puncture resistant gloves by all personnel in situations when blood and/or body fluids are present (Daha et al., 2009).
Needles must not be recapped after injections. Sharps should be collected at source of use in puncture-proof containers (usually made of metal or high-density plastic) with fitted covers. To discourage abuse, containers should be tamper-proof (difficult to open or break). Where plastic or metal containers are unavailable or too costly, containers made of dense cardboard are recommended. Needle incinerators can be another safe way of disposal. Reusable sharps must be handled with care avoiding direct handling during processing (Clarke et al., 2002).
CDC recommendations for post exposure to bloodborne pathogens (Parmeggiani et al., 2010):
• Wounds and skin sites that have been in contact with blood or body fluids should be washed with soap and water; mucous membranes should be flushed with water.
• The person whose blood or body fluid is the source of an occupational exposure should be evaluated for HBV, HCV and HIV infection.
• Post-exposure treatment should begin within 24 hours and not later than 7 days.
• Recommendations for HBV post-exposure management include initiation of the hepatitis B vaccine series to any susceptible, unvaccinated person who sustains an occupational blood or body fluid exposure. Post-exposure prophylaxis (PEP) with hepatitis B immune globulin (HBIG) and/or hepatitis B vaccine series should be considered for occupational exposures after evaluation of the hepatitis B surface antigen status of the source and the vaccination and vaccine-response status of the exposed person.
• There is no post-exposure treatment that will prevent HCV infection. For the person exposed to an HCV-positive source perform baseline testing for anti-HCV and ALT activity; and perform follow-up testing (e.g., at 4–6 months) for anti-HCV and ALT activity (if earlier diagnosis of HCV infection is desired, testing for HCV RNA may be performed at 4–6 weeks). Immune globulin and antiviral agents (e.g., interferon with or without ribavirin) are not recommended for PEP of hepatitis
• Recommendations for HIV PEP include a basic 4-week regimen of two drugs (zidovudine and lamivudine, lamivudine and stavudine or didanosine and stavudine) for most HIV exposures and an expanded regimen that includes the addition of a third drug for HIV exposures that pose an increased risk for transmission.
4. Handling of contaminated materials:
HCWs are exposed to contaminated equipment and working surfaces, protective coverings, reusable containers and glassware. All those should be cleaned and decontaminated after contact with blood or other potentially infectious materials with barrier precautions. Linens in a hospital can be a major potential source of infection since they are likely to be contaminated by patients in hospital beds. When linens are changed, they handled with barrier precautions and gathered in enclosed coded bags as soon as they are stripped from the bed and sent to the laundry (de Castro et al., 2009)..
On handling spots of blood or other spills, gloves and eye protection should be worn. Contamination should be wiped up with paper towels soaked in freshly prepared hypochlorite solution (milton or chlorine releasing tablets) containing 10,000 ppm (1%) available chlorine. If broken glass is present, first treat the spillage with hypochlorite and then carefully remove the pieces of glass with disposable forceps or scoop to a sharps bin, before wiping up. Towels and gloves should be disposed of in a yellow clinical waste bag for incineration (or an autoclave bag if in a laboratory). Hands must be washed following clearing up. Spilt blood should not be allowed to dry as potential aerosol production is greater from dried blood (CDC, 2004).

3. Transmission route based precautions:
a. Contact Precautions
In addition to standard precautions, contact precautions are indicated for patients known or suspected to have serious illnesses easily transmitted by direct patient contact or by contact with items in the patient’s environment. In addition to standard precautions, contact precautions include putting on PPE (such as gowns) prior to entry into a patient room and taking off PPE prior to exit. Patient care equipment must be dedicated with limitation of patient movement. Those patients must be placed in a private room or with patients who have active infection with the same micro-organism with no other infection (Curtis, 2008).
b. Droplet Precautions
Droplet precautions are indicated for patients known or suspected to have serious illnesses transmitted by large particle droplets, such as seasonal influenza, invasive haemophilus influenzae type b disease and invasive neisseria meningitidis. In addition to standard precautions, droplet precautions include the use of a surgical mask when working within 3 feet of the patient and the placement of the patient in a private room or with patients who have an active infection with the same micro-organism but with no other infection (Farrington, 2007).

c. Airborne Precautions
Airborne Precautions are designed to reduce the risk of airborne transmission of infectious agents as H5N1 avian influenza, SARS, measles, varicella and tuberculosis. In addition to standard precautions, airborne precautions include placement of the patient in a negative pressure room (airborne infection isolation room), if available. If a negative pressure room is not available or cannot be created with mechanical manipulation of the air, place patient in a single room. Doors to any room or area housing patients must be kept closed when not being used for entry or egress. When possible, isolation rooms should have their own hand washing sink, toilet and bath facilities (Tormo et al., 2002).
The number of persons entering the isolation room should be limited to the minimum number necessary for patient care and support. CDC recommends the use of a particulate respirator that is at least as protective as NIOSH certified N95. For patients for whom influenza is suspected or diagnosed, surveillance, vaccination, antiviral agents and use of private rooms as much as feasible is recommended. In contrast to tuberculosis, measles and varicella, the pattern of disease spread for seasonal influenza does not suggest transmission across long distances (e.g., through ventilation systems); therefore, negative pressure rooms are not needed for patients with seasonal influenza (Lateef, 2009).

4- Environmental cleaning:
Cleaning is the removal of all visible and invisible organic material (e.g., soil) from objects to prevent micro-organisms from thriving, multiplying and spreading. 90% of micro-organisms are present within “visible dirt” and the purpose of routine cleaning is to eliminate this dirt. Neither soap nor detergents have antimicrobial activity and the cleaning process depends essentially on mechanical action (Nchez-Paya et al., 2009).
There must be policies specifying the frequency of cleaning and cleaning agents used for walls, floors, windows, beds, curtains, screens, fixtures, furniture, toilets and all reused medical devices. Methods must be appropriate for the likelihood of contamination and necessary level of asepsis.
5. Disinfection of patient equipment
Disinfection removes micro-organisms without complete sterilization to prevent transmission of organisms between patients. Disinfectants must be easy to use, non-volatile and not harmful to equipment, staff or patients, free from unpleasant smells and effective within a relatively short time. Different products or processes achieve different levels of disinfection. These are classified as high, intermediate or low level disinfection. Table (8) provides characteristics of the three levels (Hedin et al., 2010).

Monday, December 5, 2011

Community-Acquired Pneumonia (CAP)

Community-acquired pneumonia (CAP) is a common health problem that may still be life threatening in an age of wide availability of effective antibiotic therapy. The annual incidence rate rises from 6/1000 in the 18–39 age group to 34/1000 in people aged 75 years and over (Blasi et.al., 2007). Hospital admission is necessary in 20–40% of cases, with 5–10% of these patients being admitted to an intensive care unit (ICU). Overall mortality from CAP is 5–10% (Hoare and Lim, 2006).

Bacterial infection
Streptococcus pneumonia
Haemophilus influenzae
Escherichia Coli
Klebsiella pneumoniae
Pseudomonas aeruginosa
Atypical infection
Mycoplasma pneumoniae
Coxiella burnetti
Chlamydia psittaci
Legionella pneumophila
Fungal infection

Viral infections
Respiratory syncytial
Adenovirus Protozoal infections
Pneumocystis carinii
Amoeboesis Others
Cystic fibrosis
Lipoid pneumonia

Saturday, December 3, 2011

Microbiological Classification of Pneumonia

Pneumonia classified according to the probable origin of infection into community acquired pneumonia or nosocomial (hospital acquired) pneumonia (Wilkinson and Woodhead, 2004).

a) Community acquired pneumonia
Community-acquired pneumonia (CAP) is defined as an infection of the alveolar or gas-exchanging portions of the lungs occurring outside the hospital, with clinical symptoms accompanied by the presence of an infiltrate in the chest radiograph (Lippi et.al., 2011).
Most bacterial infections result from aspiration of nasopharyngeal organisms, although inhalation of infected droplets from other patients, from animals, or from environmental sources , less commonly, hematogenous spread to the lung (Baltzer et.al., 2006).

b) Nosocomial pneumonia
The spectrum of nosocomial pneumonia can include hospital acquired pneumonia (HAP), health care associated pneumonia (HCAP), and ventilator associated pneumonia (VAP) (Jevtic, 2009).

Hospital acquired pneumonia is defined of pneumonia occuring at least 48 hours after hospital admission (Kollef and Micek, 2005).
It may result as a direct result of surgery (postoperative and aspiration pneumonia) but is more often a result of major co morbidity, for example chronic obstructive pulmonary disease (COPD) or general debility in elderly. Two to five percent of hospital admission are complicated by development of this condition (Yarnell, 2007).
Ventilator associated pneumonia is defined as nosocomial Pneumonia in patients receiving mechanical ventilation via an endotracheal tube that develops 48 hours or more after initiation of ventilation ( curley et. al., 2006).
Ventilator associated pneumonia is the most frequent infection in intensive care
units (ICU) and has a high mortality and morbidity rate (Bouza et.al., 2011). It occurs in 8% to 28% of patient receiving mechanical ventilation in ICU (Wu et.al., 2011).
Heath care associated pneumonia [HCAP] :- This category includes patients who a] receive home nursing, intravenous antibiotics, or wound care; b] patients who reside in nursing homes or long-term care facilities; c] patients who have been hospitalized for ≥ 2 days in the past 90 days; d] patients who have received dialysis or IV therapy at a hospital-based clinic in the past 30 days (Kronish and Dorr, 2008).