Multi-drug resistance profiles and the genetic features of Acinetobacter baumannii isolates from Bolivia

Abstract

Introduction: Acinetobacter baumannii is opportunistic in debilitated hospitalised patients. Because information from some South American countries was previously lacking, this study examined the emergence of multi-resistant A. baumannii in three hospitals in Cochabamba, Bolivia, from 2008 to 2009. Methodology: Multiplex PCR was used to identify the main resistance genes in 15 multi-resistant A. baumannii isolates. RT-PCR was used to measure gene expression. The genetic environment of these genes was also analysed by PCR amplification and sequencing. Minimum inhibitory concentrations were determined for key antibiotics and some were determined in the presence of an efflux pump inhibitor, 1-(1-napthylmethyl) piperazine. Results: Fourteen strains were found to be multi-resistant. Each strain was found to have the bla OXA-58 gene with the ISAba3-like element upstream, responsible for over-expression of the latter and subsequent carbapenem resistance. Similarly, ISAba1, upstream of the bla ADC gene caused over-expression of the latter and cephalosporin resistance; mutations in the gyrA(Ser83 to Leu) and parC (Ser-80 to Phe) genes were commensurate with fluoroquinolone resistance. In addition, the adeA, adeB efflux genes were over-expressed. All 15 isolates were positive for at least two aminoglycoside resistance genes. Conclusion: This is one of the first reports analyzing the multi-drug resistance profile of A. baumannii strains isolated in Bolivia and shows that the over-expression of thebla OXA-58 , bla ADC and efflux genes together with aminoglycoside modifying enzymes and mutations in DNA topoisomerases are responsible for the multi-resistance of the bacteria and the subsequent difficulty in treating infections caused by them.

Prevalence of extended-spectrum beta-lactamase genes in Acinetobacter baumannii strains isolated from nosocomial infections in Tehran, Iran

“…The most prevalent ESBL gene was bla TEM , which was detected in 35 (87.5%) isolates; however, bla SHV and bla VEB genes were not found [ 29 ]. Moreover, in the study by Lopes et al, the PCR technique performed to detect beta-lactamase genes in 50 isolates showed that all isolates harbored the bla TEM gene, while bla SHV and bla VEB genes were not found in any of the strains [ 38 ]. The results of these studies regarding the prevalence of bla T EM , bla T EM and bla VEB ESBL genes were similar to our results.…”

The transferability of blaOXA-23 gene in multidrug-resistant Acinetobacter baumannii isolates from Saudi Arabia and Egypt

“…The aac-6 -Ib class of aminoglycoside inactivating enzymes has been shown to confer resistance to tobramycin, dibekacin, amikacin, 5-episisomicin, netilmicin, 2 -Nethylnetilmicin and sisomicin (Lopes et al, 2013). Researchers from Turkish University Hospital had previously reported the presence of bla GES-22 gene in eight of their extensively drug resistant A. baumannii isolates (Cicek et al, 2014).…”

“…PCR was performed on all isolates as described earlier on all isolates to identify insertion elements causing disruption of the carO gene (29 kDa outer membrane protein) which leads to carbapenem resistance (Mussi et al, 2005). Additionally, primers FU and RU were used for amplification of the intergenic region upstream of the bla ADC gene and primers FD and RD were used to amplify the intergenic region downstream of the bla ADC gene (Lopes et al, 2013). The quinolone resistance mediating genes gyrA and parC were analysed for presence of mutations by PCR and sequencing as described previously (Lopes et al, 2013).…”

“…Additionally, primers FU and RU were used for amplification of the intergenic region upstream of the bla ADC gene and primers FD and RD were used to amplify the intergenic region downstream of the bla ADC gene (Lopes et al, 2013). The quinolone resistance mediating genes gyrA and parC were analysed for presence of mutations by PCR and sequencing as described previously (Lopes et al, 2013). The sequencing of the amplicons was carried out using the BigDye ® Terminator v3.1 Cycle Sequencing Kit (Applied Biosystems, USA).…”

“…Insertion sequences (IS), which are usually tightly regulated, are capable of independent transposition in the microbial genome and are important in providing genetic variability to bacteria (Mugnier et al, 2009a). ISAba1, belonging to the IS4 family, has been associated with increased expression of several antibiotic resistance genes in A. baumannii including bla OXA-51-like , bla ADC , bla OXA-23-like , bla OXA-58-like and bla OXA-235-like (Corvec et al, 2003(Corvec et al, , 2007Higgins et al, 2013;Lopes et al, 2013;Mugnier et al, 2009b). A recent study described the genetic diversity of carbapenem resistant A. baumannii strains isolated from paediatric cancer patients during the years 2010-2011, from two different medical centres in Cairo, Egypt.…”