Antibiotic Resistance Trends of Gram-negative Bacteria Most Frequently Isolated from Inpatients in a Tertiary Care Hospital in Sana'a, Yemen

Abstract

Objective: To determine the trends of antibiotic resistance of Gram-negative bacteria, most frequently isolated from inpatients at the University of Science and Technology Hospital (USTH) in Sana'a, Yemen. Methods: A retrospective, cross-sectional study on the antibiotic resistance of Gram-negative bacteria most frequently isolated from respiratory tract, pus, urine, blood and other types of specimens from inpatients admitted to the USTH. Data were retrieved from the hospital records of culture-positive inpatients in the period from January 2006 to December 2013, and annual trends of resistance were compared using chi-square test for trends at P values < 0.05. Results: Of 2005 Gram-negative bacterial isolates in the period from 2006 to 2013, the most frequently isolated species were Escherichia coli (41.6%), Acinetobacter species (26.7%), Klebsiella species (21.0%) and Pseudomonas aeruginosa (10.6%). Amikacin and carbapenems were the most active drugs against E. coli, with a decrease in the susceptibility of this species to the third- and fourth-generation cephalosporins and a variable resistance rate to quinolones that significantly increased in 2013. Acinetobacter species susceptibility to most antibiotics decreased significantly over the years of the study, where polymyxin B was the only one found to be effective against this species. On the other hand, the trend of Klebsiella species resistance to imipenem, piperacillin-tazobactam, cefepime, ceftazidime increased over the years of the study. Susceptibility of Klebsiella species to ciprofloxacin, levofloxacin and moxifloxacin showed fluctuations, while the susceptibility of aminoglycosides (amikacin and gentamicin) and ampicillin-sulbactam showed no difference. The resistance of P. aeruginosa to the majority of antibiotics was not dramatically changed over the years of the study period, but gentamicin resistance rate was considerably dropped from 77.8% in 2008 to 25.9% in 2013. Conclusions: Of the most frequently isolated Gram-negative bacteria in Sana'a, Acinetobacter species has the highest resistance rate to the most commonly used antibiotics, where only polymyxin B is effective against this species. P. aeruginosa shows an unchanging rate of resistance to antibiotics in the USTH despite being quite resistant to antibiotics on a global scale, which could be attributed to the smaller number of P. aeruginosa isolates tested over the study period. Further large-scale studies on the trends of antibiotic resistance rates in hospital-based settings and the best ways to counteract such resistance in Yemen are recommended.