Prevalence of \u03b2-lactamase-encoding genes and molecular typing of Acinetobacter baumannii isolates carrying carbapenemase OXA-24 in children

Neda Yousefi Nojookambari,Sajjad Yazdansetad,Maryam Vaezjalali,Bahram Nikmanesh,Zohreh Ghalavand,Gita Eslami,Razieh Dehbanipour,Mehrzad Sadredinamin

doi:10.1186/s12941-021-00480-5

Abstract

Backgroundβ-Lactam antibiotics have been broadly used for the treatment of Acinetobacter baumannii infections, resulting in development of β-lactam inactivating β-lactamases. Here, we described antibiotic resistance rate, prevalence of β-lactamase-encoding genes, and clonal relationships of A. baumannii strains isolated from children referred to Children’s Medical Center in Tehran, Iran, during 2019–2020.MethodsA total of 60 non-replicate A. baumannii isolates were recovered from clinical specimens of pediatric patients. Antibiotic susceptibility testing was done by the disc diffusion method. Colistin susceptibility of isolates was performed by the broth microdilution method. β-lactamase-encoding genes were characterized by PCR. The presence of ISAba1 element upstream of the several oxacillinase genes was also checked. Genetic relatedness of isolates was determined by using random amplification of polymorphic DNA (RAPD) typing.ResultsThe antimicrobial susceptibility tests showed that 83.3% of A. baumannii isolates were MDR, and 40% XDR. Both MDR and XDR A. baumannii isolates were susceptible to colistin. The frequency of blaOXA-51-like, blaOXA-23-like, blaTEM, blaOXA-24-like, blaPER, blaSHV, blaCTX-M, blaOXA-58-like, and blaIMP was 100, 93.33, 60, 36.67, 28.33, 8.33, 5, 3.33, and 1.67%, respectively. Coexistence of ISAba1/blaOXA-23-like and ISAba1/blaOXA-51-like was observed in 65% and 85% of isolates, respectively. RAPD analysis revealed 4 common types and 2 single types of A. baumannii isolates.ConclusionsThe multiple clones harboring blaOXA-23-like, ISAba1-blaOXA-51-like, and ISAba1-blaOXA-23-like were responsible for the spread of A. baumannii isolates in our clinical wards. Dissemination of the well-established clones is worrisome and would become therapeutic challenges due to the possible transferring genetic elements associated with resistance.

Highlights

Acinetobacter baumannii, a known serious human pathogen, is the most important for rising rates of hospitalacquired infections and rapid development of antibiotic and antimicrobial resistance worldwide [1]
The multiple clones harboring blaOXA-23-like, ISAba1-blaOXA-51-like, and ISAba1-blaOXA-23-like were responsible for the spread of A. baumannii isolates in our clinical wards
The majority of isolates were obtained from patients admitted to the neonatal and pediatric intensive care units (NICU, Pediatric intensive care unit (PICU)) (65%), followed by the other wards (35%)

Summary

Introduction

Acinetobacter baumannii, a known serious human pathogen, is the most important for rising rates of hospitalacquired infections and rapid development of antibiotic and antimicrobial resistance worldwide [1]. The ability of A. baumannii for environmental persistence and desiccation resistance makes it a successful pathogen to spread in healthcare settings [3]. Multidrug-resistant (MDR) A. baumannii has emerged as a significant pathogen in children with high morbidity and mortality and caused serious therapeutic problems due to the rapid acquisition of a large diversity of antibiotic-resistance genes [5]. Β-lactam antibiotics (e.g., penicillins, cephalosporins, carbapenems, and monobactams) are empirically prescribed for the treatment of infections caused by A. baumannii. Carbapenems possess potent antimicrobial activity against MDR A. baumannii, new carbapenem-hydrolyzing beta-lactamases have arisen with increasing carbapenem use resulted in a higher risk of treatment failure [8]

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