Abid Mahmood, Tariq Butt, Masood Anwar.
Bacterial pathogens causing blood stream infections in intensive care unit: Spectrum and antibiotic sensitivity pattern.
Pak J Pathol Jan ;13(4):19-22.

Blood stream infections remain one of the most challenging problems in the intensive care units (ICUs). Empirical antibiotic treatment of these depends upon the type of organisms causing the infections and their antibiotic sensitivity pattern. Keeping in view the same a study was conducted at the Department of Microbiology AFIP, Rawalpindi and ICU of Combined Military Hospital, Rawalpindi to know the pathogens responsible for blood stream infections in cases admitted in ICU and their antibiotic sensitivity pattern, so that guidelines can be provided for empirical antibiotic therapy. The study was conducted during a period extending from April 2001 to Sep 2002. Blood specimens for culture were collected from patients who developed symptoms/signs of bacteremia/septicemia 48 hours or more after admission in the ICU. The specimens were inoculated into BacT-Alert/Brain Heart Infusion (BHI) broths. The bottles were incubated at 37°C aerobically. Subcultures were done on Blood and MacConkey`s agar plates upon growth detection on BacT-Alert and on days 1,2,3,5 and 7 from BHI broths. The isolates were identified using standard biochemical tests. Antibiotic sensitivity pattern of the isolates was studied using NCCLS recommendations. Eighty five aerobic organisms were isolated. These included Staphylococcus aureus (n=15), Coagulase negative Staphylococcus (n=14), Acinetobacter spp (n=15), Escherichia coli (n=11), Klebsiella pneumoniae (n=9), Pseudomonas aeruginosa (n=8), Enterobacter cloacae (n=7), Enterococcus faecalis (n=4) and Serratia marcescans (n=2). On antibiotic sensitivity testing 38% of the Staphylococcus isolates were methicillin resistant. Susceptibility to the other drugs was also quite low while all of these were sensitive to vancomycin. In case of gram negative rods more than 80% of these were resistant to ampicillin and co-trimoxazole. Sensitivity to gentamicin was 14% and only 28% were sensitive to amikacin. Thirty five percent of these were sensitive to the third generation and 51% to fourth generation cephalosporins. More than 90% of the gram negative rods were sensitive to imipenem/meropenem and tazobactam+pipracillin. In view of the highly resistant organisms causing blood stream infections in ICU, vancomycin in combination with imipenem/meropenem or tazobactam+piracillin are the drugs of choice for empirically treating these.

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