Antimicrobial Susceptibility of Gram-Negative Infections in King Faisal Medical Complex at Taif, Saudi Arabia

Objectives: Describe susceptibility patterns to several antimicrobials in Gram-negative pathogens isolated from patients in King Faisal Medical Complex (KFMC) at Taif, Saudi Arabia over a 6-month period. Methods: The study included a cumulative antibiogram of Gram-negative bacteria (GNB). Interpretation of the antimicrobial susceptibility tests was based on the Clinical and Laboratory Standards Institute (CLSI) guidelines and the Phoenix system. Results: Overall, 763 clinical infections by GNB isolates of the specimens collected during six months were culture-positive. Among the array of GNB, Escherichia coli numbered 290 (38.0%) was the most frequently identified, then Klebsiella pneumoniae 276 (36.2%), Pseudomonas aeruginosa 77 (10.1%), Acinetobacter baumannii 48 (6.3%), Proteus spp. 31 (4.1%), Citrobacter koseri 11 (1.4%), Serratia spp. 8 (1.0 %), Enterobacter aerogenes 7 (0.9%), Klebsiella Oxytoca 4 (0.5%), Providencia rettgeri 3 (0.4 %), Klebsiella ozaenae 3 (0.4%), Morganella morganii 2 (0.3%), Stenotrophomonas maltophilia 2 (0.3 %), and Pseudomonas puda 1 (0.1%). Fifty-one isolates were resistant to all tested antibiotics, but 97 (12.7 %) were susceptible to all the tested antibiotics. The majority (87.3%) of isolates were resistant to one or more antimicrobials tested. In general, 83% of the bacterial species were MDR. The carbapenem sensitivity was 68.7% for all GNB isolates, 47.3% and 52.3% of K. pneumoniae, 20.8% and 25% of Acinetobacter, and 64.1% and 75.6% of P. aeruginosa to imipenem and meropenem, respectively. The carbapenem sensitivity for E. coli was extremely high showing 100% and 99.9% for imipenem and meropenem, respectively. Antibiotic sensitivity of the most isolated GNB pathogens was highly variable showing that tigecycline is the most effective antibiotic with 82.4% sensitivity while was non-effective for Acinetobacter. The colistin sensitivity was 88.3% for E. coli, 69.2% for P. aeruginosa, 45.5% for K. pneumoniae and less effective against A. baumannii. Conclusion: Antibiotic resistance among K. pneumoniae, A. baumannii and P. aeruginosa was high for many used antibiotics, thus continued surveillance is needed.