Detection of extended spectrum beta-lactamase genes in Pseudomonas aeruginosa isolated from patients in rural Eastern Cape Province, South Africa

Abstract

The proliferation of extended spectrum beta-lactamase (ESBL) producing Pseudomonas aeruginosa represent a major public health threat. In this study, we evaluated the antimicrobial resistance patterns of P. aeruginosa strains and characterized the ESBLs and Metallo- β-lactamases (MBL) produced. Strains of P. aeruginosa cultured from patients who attended Nelson Mandela Academic Hospital and other clinics in the four district municipalities of the Eastern Cape between August 2017 and May 2019 were identified; antimicrobial susceptibility testing was carried out against thirteen clinically relevant antibiotics using the BioMérieux VITEK 2 and confirmed by Beckman autoSCAN-4 System. Real-time PCR was done using Roche Light Cycler 2.0 to detect the presence of ESBLs; bla_SHV, bla_TEM and bla_CTX-M genes; and MBLs; bla_IMP, bla_VIM. Strains of P. aeruginosa demonstrated resistance to wide-ranging clinically relevant antibiotics including piperacillin (64.2%), followed by aztreonam (57.8%), cefepime (51.5%), ceftazidime (51.0%), piperacillin/tazobactam (50.5%), and imipenem (46.6%). A total of 75 (36.8%) multidrug-resistant (MDR) strains were observed of the total pool of isolates. The bla_TEM, bla_SHV and bla_CTX-M was detected in 79.3%, 69.5% and 31.7% isolates (n = 82), respectively. The bla_IMP was detected in 1.25% while no bla_VIM was detected in any of the strains tested. The study showed a high rate of MDR P. aeruginosa in our setting. The vast majority of these resistant strains carried bla_TEM and bla_SHV genes. Continuous monitoring of antimicrobial resistance and strict compliance towards infection prevention and control practices are the best defence against spread of MDR P. aeruginosa.