Microbiology
Mehrdad Gholami; Mohammadreza Haghshenas; Mona Moshiri; Shbnam Razavi; Abazar Pournajaf; Gholamreza Irajian; Mohsen Heidary
Abstract
Background & objective: Multidrug-resistant Acinetobacter baumannii (MDR-AB) is an important nosocomial pathogen which is associated with significant morbidity and mortality, particularly in high-risk populations. Aminoglycoside-modifying enzymes (AMEs) and 16S ribosomal RNA (16S rRNA) ...
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Background & objective: Multidrug-resistant Acinetobacter baumannii (MDR-AB) is an important nosocomial pathogen which is associated with significant morbidity and mortality, particularly in high-risk populations. Aminoglycoside-modifying enzymes (AMEs) and 16S ribosomal RNA (16S rRNA) methylation are two important mechanisms of resistance to aminoglycosides. The aim of this study was to determine the prevalence of 16S rRNA methylase (armA, rmtA, rmtB, rmtC, and rmtD), and the AME genes [aac(6′)-Ib, aac(3)-I, ant(3′′)-I, aph(3′)-I and aac(6')-Id], among clinical isolates of A. baumannii in Tehran, Iran. Methods: Between November 2015 to July 2016, a total of 110 clinical strains of A. baumannii were isolated from patients in two teaching hospitals in Tehran, Iran. Antimicrobial susceptibility testing was performed according to Clinical and Laboratory Standards Institute guidelines. The presence of genes encoding the AMEs and16S rRNA methylases responsible for resistance was investigated by multiplex polymerase chain reaction. Results: The results showed that colistin was an effective antibiotic and could be used as a last-resort treatment of infections caused by MDR-AB. The resistance rate to aminoglycosides were 100%, 96.36% and 90.9% for tobramycin, gentamicin and amikacin, respectively. In this study, AME genes of aac(6′)-Ib, aac(3)-I and ant(3′′)-I were most prevalent among the isolated strains. Conclusion Markedly high resistance to tobramycin, gentamicin and amikacin was noted in current study. Our results suggested that modifying enzyme genes in conjunction with methylation of 16S rRNA might contribute to aminoglycoside resistance induced in vivo in A. baumannii.Further studies are required to determine the prevalence of the aminoglycoside resistance genes in other hospitals of Iran.
Masoume Bina; Abazar Pournajaf; Shiva Mirkalantari; Malihe Talebi; Gholamreza Irajian
Abstract
Background and Objective: The production of carbapenemases especially Klebsiella pneumoniae carbapenemase (KPC) is the most important mechanism of enzymatic resistance in isolated Enterobacteriaceae such as K. pneumoniae. The purpose of this study was detected of the carbapenemase producer K. pneumoniae ...
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Background and Objective: The production of carbapenemases especially Klebsiella pneumoniae carbapenemase (KPC) is the most important mechanism of enzymatic resistance in isolated Enterobacteriaceae such as K. pneumoniae. The purpose of this study was detected of the carbapenemase producer K. pneumoniae strains with phenotypic and genotypic methods. Method: Out of 800 strains, 270 K. pneumoniae strains (33.7%), were obtained. Antibiotic susceptibility test was performed by disk diffusion method in accordance with CLSI guidelines. Carbapenem resistant strains were identified by the Modified Hodge Test based on CLSI instruction and PCR for surveying the presence of bla-KPC gene. Results: A total 270 K. pneumoniae strains were collected. Antibiotic susceptibility test results showed the highest and lowest resistance was related to piperacillin (60.6%) and carbapenems (14.6%) respectively. 80.5% (33 of 41) isolates were positive by MHT, but all of them (100%) were negative for amplification of the bla-KPC gene in the PCR method. Conclusion: The MHT was an appropriate method for approving carbapenemase production. Moreover, a laboratory could accept the carbapenemase production with PCR method for the bla-KPC gene, which has the additional profit of validating which KPC is present. How to cite this article: Bina M, Pournajaf A, Mirkalantari S, Talebi M, Irajian G. Detection of the Klebsiella pneumoniae carbapenemase (KPC) in K. pneumoniae Isolated from the Clinical Samples by the Phenotypic and Genotypic Methods. Iran J Pathol. 2015;10(3):199-205.
