Resistance characteristics of CTX-M type Shigella flexneri in China
Fengzhi Bian1, Mingxiao Yao2, Hongmei Fu3
1Department of Clinical Laboratory, The Fourth People's Hospital of Jinan, Jinan, Shandong Province 250031, China.
Abstract:
The present study was to identify the drug resistance, resistance mechanism and the extended-spectrum β-lactamase (ESBLs) genotypes of Shigella flexneri (S. flexneri) in Jinan. Susceptibility tests were performed by MIC-determination. The genotypes of β-lactamase were identified using PCR and DNA sequencing. The resistance transfer ability of the ESBL-producing strains was examined by conjugation tests. A total of 105 S. flexneri isolates were collected, and 34 (32.4%) were ESBL-producing isolates. All ESBL-producing isolates were susceptible to cefoxitin and imipenem, and 35.3% isolates were resistant to ciprofloxacin. ESBL-producing isolates showed high level resistant to ampicillin (100%), cefotaxime (100%), tetracycline (100%), chloramphenicol (100%), trimethoprim/sulfamethoxazole (100%), ceftazidime (73.5%) and cefepime (73.5%). Three types of β-lactamase genes (blaTEM, blaOXA and blaCTX-M) were identified in all ESBL-producing isolates, and the genotypes were confirmed as blaTEM-1 (23/34), blaOXA-30 (34/34), blaCTX-M-14 (9/34) and blaCTX-M-15 (25/34) by sequencing. In conclusion, the Shigella strains isolated in Jinan are cross-resistant and multi-drug resistant. The main genotypes of ESBLs are CTX-M-14 and CTX-M-15.
Insights
This study found that 32.4% of Shigella flexneri isolates in Jinan are extended-spectrum beta-lactamase (ESBL) producers, exhibiting multi-drug resistance. The main ESBL genotypes identified were CTX-M-14 and CTX-M-15.
Area of Science:
- Microbiology
- Molecular Biology
- Infectious Diseases
Background:
- Shigella flexneri is a significant cause of bacterial dysentery worldwide.
- The emergence of antimicrobial resistance in S. flexneri poses a serious threat to public health.
- Extended-spectrum beta-lactamases (ESBLs) are key enzymes conferring resistance to beta-lactam antibiotics.
Purpose of the Study:
- To investigate the prevalence of drug resistance and ESBL genotypes in S. flexneri isolates from Jinan.
- To understand the resistance mechanisms and transferability of resistance genes.
Main Methods:
- Antimicrobial susceptibility testing using MIC-determination.
- Identification of beta-lactamase genotypes via PCR and DNA sequencing.
- Examination of resistance transfer ability using conjugation tests.
Main Results:
- Out of 105 S. flexneri isolates, 34 (32.4%) were ESBL producers.
- ESBL-producing isolates showed high-level resistance to multiple antibiotics including ampicillin, cefotaxime, tetracycline, chloramphenicol, and trimethoprim/sulfamethoxazole.
- The identified ESBL genotypes were blaTEM-1, blaOXA-30, blaCTX-M-14, and blaCTX-M-15, with blaCTX-M-14 and blaCTX-M-15 being predominant.
Conclusions:
- Shigella strains in Jinan exhibit cross-resistance and multi-drug resistance.
- CTX-M-14 and CTX-M-15 are the primary ESBL genotypes circulating in this region.
- Continuous surveillance of antimicrobial resistance patterns and ESBL genotypes is crucial for effective treatment and control strategies.
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