Epidemiology and Antimicrobial Sensitivities of 536 Multi-Drug-Resistant Gram-Negative Bacilli Isolated from Patients Treated on Surgical Wards

Background: In this era of increasing antimicrobial resistance, infections caused by multi-drug-resistant (MDR) gram-negative bacilli (GNB) are becoming more common and pose a challenge to all clinicians, including surgeons. Methods: We evaluated the epidemiology and antimicrobial sensitivities of GNB isolated from patients treated on surgical wards at the University Hospital of Heraklion, Crete, Greece, from 2004 to 2009. The MDR isolates were defined according to an international expert proposal supported by the U. S. Centers for Disease Control and Prevention and the European Centre for Disease Prevention and Control. Results: A total of 1,153 GNB were isolated; 536 (46.5%) were MDR. The most common isolates were Escherichia coli (312 [27.8%]; MDR rate 50.2%), Pseudomonas aeruginosa (298 [25.8%]; MDR rate 39.6%), Acinetobacter baumannii (137 [11.9%]; MDR rate 83.9%), and Klebsiella pneumoniae (112 [9.7%]; MDR rate 44.6%). Most pathogens were isolated from patients hospitalized in the Departments of Surgical Oncology (32.3%), Orthopedic and Trauma Surgery (31.8%), General Surgery (18.1%), and Pediatric Surgery (15.5%). The clinical specimens comprised pus (45.1%), normally sterile fluids (22.5%), urine (16.8%), blood (6.3%), and other body fluids. Most effective in vitro against all MDR pathogens were colistin (83%), meropenem (57%), and imipenem-cilastatin (56%). The MDR P. aeruginosa was susceptible most often to colistin (94%) and aminoglycosides (tobramycin 56%, amikacin 55%), MDR A. baumannii only to colistin (94%), and MDR K. pneumoniae to meropenem (92%) and aminoglycosides (amikacin 76%, gentamicin 74%). Conclusion: In a region with a high prevalence of antibiotic resistance, almost one-half of GNB isolated from surgical patients were MDR. Surgeons may consider these developments to guide empiric antibiotic therapy for infections caused by gram-negative pathogens.