Occurrence of bla DHA-1 mediated cephalosporin resistance in Escherichia coli and their transcriptional response against cephalosporin stress: a report from India

Abstract

BackgroundTreatment alternatives for DHA-1 harboring strains are challenging as it confers resistance to broad spectrum cephalosporins and may further limit treatment option when expressed at higher levels. Therefore, this study was designed to know the prevalence of DHA genes and analyse the transcription level of DHA-1 against different β-lactam stress.MethodsScreening of AmpC β-lactamase phenotypically by modified three dimensional extract method followed by Antimicrobial Susceptibility and MIC determination. Genotyping screening of β-lactamase genes was performed by PCR assay followed by their sequencing. The bla DHA-1 transcriptional response was evaluated under different cephalosporin stress by RT PCR. Transferability of bla DHA gene was performed by transformation and conjugation and plasmid incompatibility typing, DNA fingerprinting by enterobacterial repetitive intergenic consensus sequences PCR.Results16 DHA-1 genes were screened positive from 176 Escherichia coli isolates and primer extension analysis showed a significant increase in DHA-1 mRNA transcription in response to cefotaxime at 8 µg/ml (6.99 × 102 fold), ceftriaxone at 2 µg/ml (2.63 × 103 fold), ceftazidime at 8 µg/ml (7.06 × 103 fold) and cefoxitin at 4 µg/ml (3.60 × 104 fold) when compared with untreated strain. These transcription data were found significant when analyzed statistically using one way ANOVA. Four different ESBL genes were detected in 10 isolates which include CTX-M (n = 6), SHV (n = 4), TEM (n = 3) and OXA-10 (n = 1), whereas, carbapenemase gene (NDM) was detected only in one isolate. Other plasmid mediated AmpC β-lactamases CIT (n = 9), EBC (n = 2) were detected in nine isolates. All DHA-1 genes detected were encoded in plasmid and incompatibility typing from the transformants indicated that the plasmid encoding bla DHA-1 was carried mostly by the FIA and L/M Inc group.ConclusionThis study demonstrates the prevalence of DHA-1 gene in this region and highlights high transcription of DHA-1 when induced with different β-lactam antibiotics. Therefore, cephalosporin treatment must be restricted for the patients infected with pathogen expressing this resistance determinant.

Phenotypic and Genotypic Characteristics of Uropathogenic Escherichia coli Isolates from Kenya

“…11 Chromosomally mediated AmpC genes do not cause resistance to cephalosporins unless they are overproduced. 22 b-Lactams are often used for the empirical treatment of UTI. Despite the changing epidemiology of ESBL genes, there are insufficient data on the occurrence of b-lactam genes in E. coli isolates from UTI patients in Kenya.…”

Identification of Ampc Β-Lactamase-Producing Clinical Isolates of Escherichia Coli

“…A number of workers have used PCR to detect the presence of ampC genes E. coli and have reported PCR to be more sensitive than phenotypic methods to detect AmpC-producing isolates [4,[30][31][32]. Our study showed the presence of ampC gene for plasmid-mediated AmpC enzymes in 47% of the screen-positive isolates of E. coli and was found to detect four additional AmpC producers than inhibitor-based method.…”

Genetic markers of antibiotic resistance of pathogenic bacteria in the milk of cows and goats

“…The obtained data on the regional distribution of bacterial pathogens suggest that in all the incoming milk samples from cows from5 regions of the Russian Federation, DNA of Staphylococcus spp., As well as E. coli, was most often detected. The greatest distribution of monocultures of microorganisms had the: Staphylococcus spp.…”

“…Currently, 24 types of DHA genes are known. The regulation of this expression of β-lactamase is closely related to the recirculation of the cell wall [5,13]. The ErmB gene determines the resistance of Staphylococcus spp.…”