Low prevalence of metallo-beta-lactamase in Pseudomonas aeruginosa isolated from a tertiary burn care center in Tehran

Abstract

Production of metallo-beta-lactamase (MBL) is one of the main mechanisms for resistance in carbapenem antibiotics. Detection of MBL-producer Pseudomonas aeruginosa is crucial in preventing its spread to other gram-negative bacteria. The aim of this study was to evaluate combination disc (CD) for identification of MBL-producer P. aeruginosa by polymerase chain reaction (PCR). A total of 255 imipenem resistant P. aeruginosa were collected from burn patients. Antibiotic susceptibility testing was conducted after purification and identification. Double-disc synergy test (DDST) with EDTA and combination disc test (CDT) with dipicolinic acid were performed for phenotypic detection of MBL and the PCR was carried out for blaVIM, blaIMP, blaNDM-1, blaSPM-1 genes. DDST with EDTA was negative in all cases, but 161 isolates were positive in CDT with dipicolinic acid. Further, blaVIM and blaIMP were detected in five and four strains, respectively. None of the isolates were positive for BlaNDM-1 and blaSPM-1 . The results of this study showed that the prevalence of MBL is low in imipenem resistance P. aeruginosa and that other mechanisms could be involved in resistance to imipenem in this bacterium.

Colistin-resistant Pseudomonas aeruginosa clinical strains with defective biofilm formation

“…P. aeruginosa is one of a considerable number of Gram-negative bacteria that can cause nosocomial infections, especially in burn patients [1], [2], [3], [4], [5]. Monitoring P. aeruginosa in health care centers is very important, because it has great ability to survive in the hospital environment, its intrinsic antibiotic resistance mechanisms, and its potential for acquiring antibiotic-resistance genes [1], [2], [4].…”

“…Monitoring P. aeruginosa in health care centers is very important, because it has great ability to survive in the hospital environment, its intrinsic antibiotic resistance mechanisms, and its potential for acquiring antibiotic-resistance genes [1], [2], [4]. Extensive drug-resistant (XDR) and MDR strains of P. aeruginosa can increase morbidity and mortality especially in hospitalized and immune-suppressed patients [1], [2], [3], [4], [5]. …”

“…Unfortunately, carbapenem-resistant strains have been reported worldwide, and in such cases, colistin remains the only effective antibiotic despite its nephrotoxicity [1], [2], [3], [4], [5], [6]. Up to 2016, all of the detected colistin-resistance mechanisms were attributed to chromosomal genes.…”

“…Multi-drug resistant (MDR) Pseudomonas aeruginosa strains are increasingly isolated from clinical specimens worldwide, which is cause for global concern [1], [2], [3], [4]. In some cases, only colistin remains as an effective antibiotic.…”

“…In some cases, only colistin remains as an effective antibiotic. However, this is problematic due to the nephrotoxicity of colistin and resistance to it, which can increase morbidity and mortality especially in immunosuppressed patients (e.g, hospitalized persons) [1], [2], [3], [4], [5], [6]. Colistin-resistant P. aeruginosa can be related to two chromosomal mutations: 1) modification of lipid A and 2) loss of LPS [7].…”