The Prevalence of Carbapenemase Genes in Carbapenem-resistant Gram-negative Bacilli, Masih Daneshvari Hospital, Tehran, Iran, 2019-2020

 Carbapenem-resistant Enterobacteriaceae (CRE) are rapidly growing, which makes it vital to detect antibacterial activity. However, the carbapenem family does not have an automated antimicrobial susceptibility testing card. So the aim of this study was to identify the prevalence of carbapenemase-producing strains of Gram-negative bacteria and determine their antibiotic susceptibility pattern in Tehran, Iran.

 In this cross-sectional study, between 2019 and 2020, 1600 samples were taken from the Masih Daneshvari hospital's laboratory in Iran. Utilizing standard biochemical methods, all isolated bacteria were identified. The common Kirby-Bauer Disc diffusion method was used for antimicrobial susceptibility testing. A real-time polymerase chain reaction was used to evaluate the molecular detection of genes producing carbapenemase.

Of 1502 (94.7) Gram-negative bacilli, 37.3% isolates were Pseudomonas aeruginosa, 30.6% Acinetobacter baumannii, 16.5% Klebsiella, 9.3% Escherichia coli, 0.6% Pseudomonas multophila, 0.4% Neisseria1105 (73.5%) isolates were carbapenem-sensitive, while the remaining 397 (26.5%) isolates were carbapenem-resistant. Molecular testing of this sample showed that 80% of tested isolates had resistance genes to at least one antibiotic resistance gene. The following carbapenemase genes were most frequently detected among resistant strains: blaimp (35%), blavim (20%), blakpc (15%), blaoxa -48 (10%), blandm (10%), and blages (10%).

 From this study authors can conclude that carbapenemase-producing Enterobacteriaceae is increasing in Iran and the use of phenotypic methods for detection of CPEs showed good sensitivity. Before prescribing antibiotics to patients, this test should be performed.