Wednesday, October 5, 2011

Healthcare workers acquired infections (HCWAIs)

HCWs are personnel who are in contact with patients, body fluids, specimens and having high risk of acquiring and transmitting infections. HCW include physicians, nurses, laboratory personnel, technicians, pharmacists, workers and students in educational hospitals (de Castro et al., 2009).
Routes of healthcare workers acquired infection:
The transmission of HCAIs requires three elements: source of infecting micro-organisms, mode of transmission and susceptible host. The human source of hospital acquired infections may be patients, hospital personnel or visitors. These people may have infectious diseases, but may be in the incubation period, or may be chronic carriers (Garner et al., 1996).

1. Bio-aerosols transmission:
Close proximity of persons together with handling of human secretions (e.g.: respiratory secretions) make HCWs particularly vulnerable to transmission of droplet-transmitted respiratory infections. This was tragically highlighted during the international outbreak of severe acute respiratory syndrome (SARS) in 2003 with attack rates of more than 50% in HCWs before infection control measures were instituted (Kin et al., 2007).
Airborne nosocomial infections are transmitted directly or indirectly through air and may cause respiratory (primarily pneumonia), surgical-site infections (SSIS), some urinary tract infections and even some blood infections, as these infections may be resulted from airborne microbes settling on equipment. In intensive care units (ICUs), almost a third of nosocomial infections are respiratory in nature, but not all are airborne; are transmitted by contact route. SSIs are non-respiratory, but may be partly airborne in origin (Curtis, 2008).
Many humans are subjected to a whole range of viral and bacterial diseases such as measles and tuberculosis, which are transmitted via the airborne route from one infectious individual to another susceptible victim. Infectious aerosols tend to be extremely small (< 5μm) and can therefore remain suspended and viable in the air stream over long periods of time. As a result the risk of airborne infection in high-risk locations (hospitals and clinics) and confined spaces (trains and aeroplanes) is extremely high.

Droplet nuclei are formed by the evaporation of droplets produced when an infected person coughs or sneezes. An infected person coughing or sneezing will produce 1000’s of droplet nuclei many of which may contain pathogenic micro-organisms. Levels of airborne microbes are not routinely checked in hospitals; however, a variety of studies have indicated that the air in hospital areas rarely, if ever, is sterile (Holcatova et al., 1993).
2. Surface contact transmission:
Direct surface transmission is very important because most pathogenic bacteria could not survive as bio-aerosols and spread significant distances to infect HCWs. However, many airborne pathogenic bacteria are viable but not culturable and some experts have estimated that as little as 1% of viable bacteria are culturable by standard microbiological techniques (Boyce, 2007).
Actually, a large percentage of HCAIs spread through surface contact infectious agent transmitted directly or indirectly from one infected to a patient or HCWs, often on the contaminated hands of a healthcare worker or by catheters, intravenous (IV) lines or surgical incisions (Curtis, 2008).
Contaminated environmental surfaces (such as bedside rails) are also an under-recognized source of hospital infections. Many surfaces in hospitals contain viable pathogens such as methicillin resistant Staph aureus (MRSA) and vancomycin resistant Enterobacteria (VRE) (Vonberg and Gastmeier, 2007).

3-Bloodborne infections:
Needle stick injuries and cuts are the common occupational accidents exposing healthcare workers (HCWs) to blood and body fluids. These preventable injuries expose workers to over 20 different bloodborne pathogens and result in an estimated 1000 infections per year, the most common being HBV, HCV and HIV (Daha et al., 2009).
Clarke et al. (2002) in their study found that the probability of ever having a needle stick injury was inversely related to years of experience. This idea is supported by Samir and Amitav (2008) studying for self-reported occupational exposure to blood and body fluids, which was fairly high, ranging from the lowest incidence of 21% among residents to more than 39% among the nurses. Junior doctors had a higher incidence of exposure as compared to residents. This may be due to their inexperience in practical procedures.
The United States National surveillance system for HCWs (NaSH) identified six devices that are responsible for the majority of needle stick and other sharp related injuries. These are hypodermic needles (32%), suture needles (19%), winged steel needles (butterfly) (12%), scalpel blades, IV catheter stylets (9%) and phlebotomy needles (3%). The most common circumstances that cause injuries in NaSH hospitals involve hollow bore needles, which are the most risky because these needles can be filled with blood. Situations of injury include the following: manipulating needle in patient (26%), disposal (12%), collision with worker or sharps (10%), during clean-up (9%), accessing IV lines (5%) and recapping needles (6%) (CDC, 2004).

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