Antimicrobial susceptibility and metallo-β-lactamase production among Pseudomonas aeruginosa isolated from Makkah Hospitals

Objectives: Pseudomonas aeruginosa is the most prevalent pathogen in nosocomial infections— it produces metallo-β-lactamases (MBLs) that reduce antibiotic effectiveness. This study aimed to determine the frequency, antimicrobial-susceptibility patterns, and MBL types of P. aeruginosa infections in clinical specimens obtained from patients in Makkah hospitals. Methodology: Clinical isolates (478) were collected during a 6-month period, from September 2009 (Ramadan 1430 AH), from various clinical wards of Al-Noor Specialist, Hera General, and King Abdul-Aziz Hospitals. All isolates were subjected to routine microbiological investigations and automated antibiotic-susceptibility testing. MBL production was assessed using double-disk synergy test by comparing the zone of inhibition given by disks containing imipenem with and without ethylene diaminetetraacetic acid (EDTA) and MBL types distinguished by polymerase chain reaction. Results: Most P. aeruginosa strains (31%) were isolated from intensive care units (ICUs) and male medical wards (15.9%). P. aeruginosa mostly caused respiratory tract (52%), wound (26%), and urinary tract (12%) infections. P. aeruginosa was most susceptible to imipenem (65.9%), amikacin (62.7%), meropenem (58.7%), and piperacillin/tazobactam (57.2 %). MBL-producing P. aeruginosa were identified in 76 (15.9%) isolates. The rate of MBLs types were 21% and 18.4% for IMP and VIM, respectively. Conclusions: These results can be used as guidelines for treatment of bacterial infections in Saudi Arabia. Multidrug-resistant and MBL-producing P. aeruginosa is a serious public health concern, which must be tackled.