Molecular detection of aminoglycoside-modifying enzyme genes in Acinetobacter baumannii clinical isolates

Abstract

Acinetobacter baumannii is a major opportunistic pathogen in healthcare settings worldwide. In Iran, there are only few reports on the prevalence of aminoglycoside resistance genes among A. baumannii isolates. The aim of this study was to investigate the existence of aminoglycoside-modifying enzyme (AME) genes from A. baumannii strains collected at a university teaching hospital in Iran. One hundred A. baumannii strains were collected between 2014 and 2015 from hospitalized patients at Loghman Hakim Hospital, Tehran, Iran. Antimicrobial susceptibility was determined by disk diffusion method according to the Clinical and Laboratory Standards Institute recommendations. The DNA was extracted using a kit obtained from Bioneer Co. (Korea) and was used as a template for polymerase chain reaction. The most active antimicrobial agent against these strains was colistin. The rate of extended-spectrum cephalosporin resistance was 97%. The aadA1, aadB, aac(6′)-Ib, and aac(3)-IIa genes were found in 85%, 77%, 72%, and 68% of A. baumannii isolates, respectively. This study showed a high prevalence rate of AME genes in A. baumannii. This prevalence rate has explained that further aminoglycoside resistance genes may have role in the resistance of clinical isolates of A. baumannii. Therefore, control and treatment of serious infections caused by this opportunistic pathogen should be given more consideration.

Distribution of Aminoglycoside Resistance Genes Among Acinetobacter Baumannii Strains Isolated From Burn Patients in Tehran, Iran

“…Due to the formation of multi-resistant A.baumannii strains and its rapid spread, it is highly difficult to treat the infections caused the bacteria these days. Currently, the bacteria are considered as factors of mortality among hospitalized patients in hospital wards (18). Several sudden outbreaks of the bacteria are reported annually from hospitals around the world, indicating the importance of the bacteria and the need for a suitable plan to prevent infection, particularly by resistant strains.…”

<p>Prevalence and antimicrobial resistance of <em>Shigella</em> species isolated from diarrheal patients in Ahvaz, southwest Iran</p>

“…PCR amplification was performed to detect the ipaH gene in Shigella isolates 13. Amplification of the ipaH gene was carried out using a thermal gradient cycler (Eppendorf Co., Hamburg, Germany) with the following protocol14,15: the PCR mixture contained 2.5 mL of 10× buffer (10 mM Tris-HCl and 50 mM KCl), 1.5 mM MgCl 2 , 3 µL of DNA template, 200 µM each dNTPs, 0.4 µM of each forward and reverse ipaH primer, 0.75 U of Taq polymerase, and sterilized distilled water to complete the reaction volume (25 µL).…”

Antibiotic Resistance Profiles, Molecular Mechanisms and Innovative Treatment Strategies of Acinetobacter baumannii

“…Depending on the mechanism by which it acts, AMEs are classified into acetyltransferases, phosphotransferases and nucleotidyl transferases [ 161 , 162 ]. The main AMEs involved in AGR in A. baumannii are aac (3′)-I , aph (3′)-I , aph (3′)-VI , aac (6′)-Ib , ant (2″)-Ia, ant (3′)–I , aac(3)-Ia [aacC1], aac(3)-IIa [aacC2], aac(6′)-Ib [aacA4], aac(6′)-Ih, aac(6′)-Im, aph(3′)-Ia [aphA1], aph(3′) -VIa [aphA6], ant(3″)Ia [aadA1] and ant(2″)-Ia [aadB] , aac(6′)-I ad, aac(6′)-II and ant(4′)-I [ 163 , 164 , 165 , 166 , 167 , 168 , 169 , 170 , 171 , 172 , 173 ]. Genes encoding AMEs can be transferred as part of gene cassettes in the case of integrons, as well as through conjugation mechanisms [ 174 ].…”

“…Enzymatic modification of AGs through production of aminoglycoside-modifying enzymes (AMEs) is the main mechanism of resistance in A. baumannii. Depending on the mechanism by which it acts, AMEs are classified into acetyltransferases, phosphotransferases and nucleotidyl transferases [161,162] 6)-II and ant(4 )-I [163][164][165][166][167][168][169][170][171][172][173]. Genes encoding AMEs can be transferred as part of gene cassettes in the case of integrons, as well as through conjugation mechanisms [174].…”