The Problem of Antimicrobial Resistance in Nosocomial Medical and Surgical Intensive Care Units Infections in a University Hospital; a Two-Year Prospective Study

Aim: To determine the frequency of nosocomial infections (NIs) and the antimicrobial resistance of pathogens isolated from patients admitted to 4 intensive care units (ICUs) at a university hospital. Materials and Methods: The patients were prospectively followed over 2 years in medical, surgical, and reanimation ICUs. The isolates were collected from patients with NI determined by the Center for Diseases Control and Prevention criteria. The identification was performed and susceptibility to antibiotics was determined in an automated system Sceptor (Becton Dickinson) as described by the CCLS. Results: Among the 3962 patients in the ICUs, total NI incidence was 6.9%, with the highest rate in the reanimation ICU (14.7%) and the lowest rate in the surgical ICU (2.5%). In all, 492 NI episodes were diagnosed in 272 patients. The incidence of NIs was 13.1 per 1000 patient days. The NIs were urinary tract infections(32%), primary blood stream infections (24%), pneumonia (20%), surgical-site infections (13%), and other infections (11%). Pneumonia was the most common NI in the reanimation ICU (54%). The pathogens were 39% gram-positive bacteria, 52% gram-negative bacteria, and 9% Candida species. S. aureus (18%) was the most frequently isolated bacteria, followed by P. aeruginosa (16%), Acinetobacter spp. (10%), coagulase negative staphylococcus (CNS) (10%), Klebsiella (9%), E. coli (9%), and Enterococcus spp. (9%). Resistance to methicillin was 90% in S. aureus isolates and was 95% in the CNS isolates; no resistance was detected to vancomycin in S.aureus and CNS isolates. Eight percent of Enterococcus isolates were resistant to vancomycin. Against the gram-negative bacteria the carbapenems were most active, followed by amikacin and ciprofloxacin. Five percent of P.aeruginosa and 15% of Acinetobacter spp. were resistant to all antibiotics. The most active antimicrobial agents against Acinetobacter spp. were imipenem (73%) and tobramycin (46%); against Pseudomonas spp. were ticarcillin/clavulanate (56%), piperacillin (44%), and imipenem (33%); against Klebsiella spp. was imipenem(92%); against E. coli were imipenem (94%), amikacin (94%), and ciprofloxacin (74%); and against Enterobacter spp. were ciprofloxacin (89%) and imipenem (78%). Conclusions: The high rates of resistant pathogens responsible for NI in ICUs suggest that infection preventive procedures should be implemented and antimicrobial agents must be used appropriately.