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Emergence of Enterobacteriaceae co-producing CTX-M-15, ArmA and PMQR in Poland
Katarzyna Piekarska1, Katarzyna Zacharczuk1, Tomasz Wołkowicz1
1Department of Bacteriology, National Institute of Public Health-National Institute of Hygiene, Warszawa, Poland.
Background:
Plasmid-mediated extended-spectrum β-lactamases (ESBLs), 16S rRNA methylases and quinolone resistance mechanisms (PMQRs) are well-known agents conferring resistance to more than 1 antimicrobial in its group. The accumulation of these agents poses, therefore, a serious risk to public health.
Objectives:
The objective of this study was to investigate the presence of common ß-lactamases and 16S rRNA methylases in Qnr-producing Enterobacteriaceae and their genetic relatedness.
Material And Methods:
We examined 18 Qnr-producing isolates (Klebsiella pneumoniae n = 8, Enterobacter cloacae n = 6 and Escherichia coli n = 4) selected from a collection of 215 ciprofloxacin-resistant strains obtained from patients in a 1030-bed tertiary hospital from 1 March to 31 August 2010. The antibiotics minimum inhibitory concentration (MIC) was determined by E-test. The detection of common ß-lactamases, 16S rRNA methyltransferases and PMQR genes was performed by polymerase chain reaction (PCR) and sequencing. Genetic relatedness was assessed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).
Results:
All the isolates tested were susceptible to carbapenems and colistin, while 16 were multidrug-resistant. Thirteen, 2 and 2 isolates carried qnrB1, qnrA1 and qnrS1, respectively. Ten of 13 qnrB1-positive Enterobacteriaceae also carried genes encoding for aac(6')-Ib-cr and at least 1 ESBL. The blaCTX-M-15 gene was the most common ESBL. The most prevalent combination of genes was qnrB1+aac(6')-Ib-cr+blaTEM-1+blaCTX-M-15. Two isolates of K. pneumoniae and E. cloacae were found to bear multiple extended range resistance traits: ArmA, CTX-M-15, QnrB1, and AAC (6')-Ib-cr. The PFGE showed that most of the isolates exhibited individual DNA patterns, whilst MLST assigned K. pneumoniae (n = 8) to 5 sequence types (STs) (ST15, ST323, ST336, ST147, and ST525), E. coli (n = 4) to 2 (ST131 and ST1431) and E. cloacae (n = 5) to 4 (ST90, ST89, ST133, and the novel ST407).
Conclusions:
Our findings reveal the accumulation of resistance traits and their important role in spreading of multiresistant bacteria among hospitalized patients.
Insights
Multidrug-resistant Enterobacteriaceae carrying plasmid-mediated quinolone resistance mechanisms (PMQRs), extended-spectrum β-lactamases (ESBLs), and 16S rRNA methylases were identified in hospitalized patients. These accumulating resistance traits contribute to the spread of multiresistant bacteria.
Area of Science:
- Microbiology
- Genetics
- Public Health
Background:
- Plasmid-mediated resistance genes, including extended-spectrum β-lactamases (ESBLs), 16S rRNA methylases, and quinolone resistance mechanisms (PMQRs), confer resistance to multiple antibiotics.
- The co-occurrence of these resistance determinants poses a significant threat to public health due to the potential for rapid dissemination.
Purpose of the Study:
- To investigate the prevalence of common β-lactamases and 16S rRNA methylases in Qnr-producing Enterobacteriaceae.
- To determine the genetic relatedness of these multidrug-resistant isolates.
Main Methods:
- Analysis of 18 Qnr-producing Enterobacteriaceae isolates (Klebsiella pneumoniae, Enterobacter cloacae, Escherichia coli) from ciprofloxacin-resistant strains.
- Detection of resistance genes using polymerase chain reaction (PCR) and sequencing.
- Assessment of genetic relatedness via pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).
Main Results:
- Sixteen of 18 isolates were multidrug-resistant, with qnrB1 being the most common Qnr gene.
- Co-occurrence of qnrB1 with aac(6')-Ib-cr and ESBL genes (blaCTX-M-15 most frequent) was observed in 10 isolates.
- Two isolates exhibited multiple resistance traits, including ArmA, CTX-M-15, QnrB1, and AAC(6')-Ib-cr.
- MLST revealed diverse sequence types within K. pneumoniae, E. coli, and E. cloacae, including a novel ST407 in E. cloacae.
Conclusions:
- The study highlights the significant accumulation of diverse antibiotic resistance genes in Enterobacteriaceae within a hospital setting.
- These findings underscore the critical role of combined resistance mechanisms in the spread of multidrug-resistant bacteria among hospitalized patients.
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