Frequency of multidrug-resistant Pseudomonas aeruginosa in patients with ventilator associated pneumonia

Ventilator associated pneumonia (VAP) is one of the most common nosocomial infections among patients in Intensive Care Unit (ICU)، which has high mortality rate. Among the common agents، Pseudomonas aeruginosa (P. aeruginosa) is the most common causative agents of VAP incidence and resistance to a wide range of antibiotics is increasing. The aim of this study was to assess the prevalence of P. aeruginosa and its drug susceptibility pattern.

This sectional survey has carried out for a year on ICU patients of Ayatollah Kashani hospital who received mechanical ventilation during Oct 2010 to Oct 2011. Sixty eight samples of endotracheal tubes were collected from the patients with signs of pulmonary infection which included fever، purulent secretions، and leucocytosis. Samples were cultured and strains isolated were identified by microbiological standard methods. Antibiotic susceptibility testing was performed on isolates using disc diffusion method and results were interpreted using Clinical and Laboratory Standards Institute guidelines. Antibiotics were grouped into the 4 following categories: 1) Cephalosporins (Ceftazidime، Cefepime)، 2) Fluroquinolones (Ciprofloxacin)، 3) Aminoglycosides (Gentamycin، Tobramycin، and Amikacin) and 4) Carbapenems (Imipenem).

Out of 68 endotracheal samples، VAP was confirmed in 46 cases (67. 7%) of these patients. The most common microorganism recovered was P. aeruginosa (15 cases، 32. 6%)، others were included: Methicillin-resistannt Staphylococcus aureus or MRSA (8 cases، 17/4%)، Klebsiella pneumonia (10 cases، 21/7%)، Escherichia coli (7 cases، 15. 2%)، Enterobacter (3 cases، 6. 5%)، Acinetobacter (2 cases، 4. 3%) and 1 case of Citobacter (2. 3%). 75% of P. aeruginosa isolated were MDR (resistant to ≥3 classes of antibiotics) and 50% of isolates were resistant to all classes of antibiotics.

Due to the increasing prevalence of Pseudomonas MDR، developing strict protocols to prevent increase in drug resistance bacteria appears to be necessary.