Wednesday, August 24, 2011

Nosocomial infections caused by Ps. aeruginosa

Ps. aeruginsa is commonly isolated from ICUs. It is responsible for a variety of infections in patients who have risk factors as surgery, immunosuppression, use of catheters and use of endotracheal tubes mainly in ICUs (Bergogne-Bérézin, 2004).
1- Lower respiratory tract infections
The respiratory tract remains the most frequent site of infection caused by Ps. aeruginosa. In 2003, Ps. aeruginosa was the second commonly reported gram-negative pathogen causing nosocomial pneumonia ICU (Gaynes et al., 2005).
2- Bacteremia
Ps. aeruginosa remains one of the most feared organisms that cause bacteremia. Recent publications show attributable mortality rates of 28 % to 44 % depending on adequacy of treatment and the seriousness of the underlying diseases (Kang et al., 2003). Pseudomonas bacteremia is particularly common in patients who have hematological malignancy or high risk factors. It may occur following instrumentaion procedures using contaminated equipment or solutions (Bergogne-Bérézin, 2004).
3- Urinary tract infections (UTI)
Ps. aeruginosa urinary tract infections generally occur as a complication of urinary tract catheterization or surgery or the presence of genitourinary obstruction (Pier and Ramphal, 2005). In 2003, Ps. aeruginosa was the second commoly reported gram-negative pathogen causing nosocomial UTI in ICU (Gaynes et al., 2005).
4- Burn and wound infections
Ps. aeruginosa is the most common cause of burn sepsis. Ps. aeruginosa is able to take advantage of the poorly perfused tissue, grow in this site and eventually achieve a denisty in the wound sufficient to allow it to seed the blood at high levels (Pier and Ramphal, 2005).
Resistance to antibiotics
Ps. aeruginosa is a notoriously difficult organism to control with antibiotics or disinfectants (Hancock, 1998). It is resistant to antibiotics due to a combination of factors: it is intrinsically resistant to antimicrobial agents due to low permeability of its cell wall, It has the genetic capacity to express a wide repertoire of resistance mechanisms, it can become resistant through mutation in chromosomal genes which regulate resistance genes and finally it can acquire additional resistance genes from other organisms via plasmids, transposons and bacteriophages (Lambert, 2002).

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