Antimicrobial susceptibility pattern of Gram-negative bacilli isolated from a Teaching Hospital in Jeddah, Saudi Arabia

Gram-negative bacilli (GNB) are commonly implicated in clinical diseases. However, with their increasing resistance to antimicrobial agents, treatment becomes a challenge. This study has been conducted at King Abdulaziz University Hospital in Jeddah, Saudi Arabia over a period of one month from July to August 2011. Identification and antibiotic sensitivity tests of GNB were performed using standard microbiological methods and Vitek2 system. Extended spectrum beta lactamase (ESBLs) strains were detected using double disc synergy test and Vitek 2 system. A total of 176 Gram-negative bacilli were studied. The most frequently isolated organism was E. coli (38.07%) followed by Klebsiella pneumoniae (15.91%), Pseudomonas aeruginosa (11.93%), Proteus mirabilis (9.66%) and Acinetobacter baumannii (6.82%). Other Gram-negative bacilli were less frequent. Isolates were detected most frequently from ICU patients (26.70%). Urinary tract, wound and respiratory tract infections were implicated most often. Extended spectrum beta lactamase strains accounted for 20% of all Enterobacteriacae. The vast majority of the GNB isolates were resistant to many antibiotics. Carbapenems, tigecycline and amikacin were effective against most multi-drug resistant Enterobacteriacae. Pseudomonas aeruginosa was resistant to several antibiotics; most effective agents were ceftazidime (80.95%), aztreonam (76.19%), carbapenem (90.48%), amikacin (90.48%), fluoroquinolones (80.95%) and piperacillin (61.90%). Isolates of Acinetobacter baumannii and Stenotrophomonas maltophilia were mainly multi-drug resistant to most tested antibiotics. In view of high levels of antibiotic resistance encountered, continuous surveillance of antimicrobial susceptibility patterns is warranted.   Key words: Gram-negative bacilli, resistance, extended-spectrum beta lactamase, intensive care unit, antibiotics, Enterobacteriaceae, King Abdulaziz University Hospital, multi-drug resistant.