Wide spread and diversity of mutation in the gyrA gene of quinolone-resistant Corynebacterium striatum strains isolated from three tertiary hospitals in China

Abstract

Background Corynebacterium striatum was confirmed to be an important opportunistic pathogen, which could lead to multiple-site infections and presented high prevalence of multidrug resistance, particularly to quinolone antibiotics. This study aimed to investigate the mechanism underlying resistance to quinolones and the epidemiological features of 410 quinolone-resistant C. striatum clinical strains isolated from three tertiary hospitals in China. Methods A total of 410 C. striatum clinical strains were isolated from different clinical samples of patients admitted to three tertiary teaching hospitals in China. Antibiotic susceptibility testing was performed using the microdilution broth method and pulsed-field gel electrophoresis (PFGE) was used for genotyping. Gene sequencing was used to identify possible mutations in the quinolone resistance-determining regions (QRDRs) of gyrA. Results In total, 410 C. striatum isolates were sensitive to vancomycin, linezolid, and daptomycin but resistant to ciprofloxacin. Depending on the antibiotic susceptibility testing results of 12 antimicrobial agents, the 410 C. striatum strains were classified into 12 resistant biotypes; of these, the three biotypes R1, R2, and R3 were dominant and accounted for 47.3% (194/410), 21.0% (86/410), and 23.2% (95/410) of the resistant biotypes, respectively. Mutations in the QRDRs ofgyrA were detected in all quinolone-resistant C. striatum isolates, and 97.3% of the isolates (399/410) showed double mutations in codons 87 and 91 of the QRDRs of gyrA. Ser-87 to Phe-87 and Asp-91 to Ala-91 double mutation in C. striatum was the most prevalent and accounted for 72.2% (296/410) of all mutations. Four new mutations in gyrA were identified in this study; these included Ser-87 to Tyr-87 and Asp-91 to Ala-91 (double mutation, 101 isolates); Ser-87 to Val-87 and Asp-91 toGly-91 (double mutation, one isolate); Ser-87 to Val-87 and Asp-91 to Ala-91 (double mutation, one isolate); and Ser-87 to Ile-87 (single mutation, one isolate). The minimum inhibitory concentration of ciprofloxacin for isolates with double (96.5%; 385/399) and single (72.7%; 8/11) mutations was high (≥ 32 µg/mL). Based on the PFGE typing results, 101 randomly selected C. striatum strains were classified into 50 genotypes (T01-T50), including the three multidrug-resistant epidemic clones T02, T06, and T28; these accounted for 14.9% (15/101), 5.9% (6/101), and 11.9% (12/101) of all genotypes, respectively. The multidrug-resistant T02 clone was identified in hospitals A and C and persisted from 2016 to 2018. Three outbreaks resulting from the T02, T06, and T28 clones were observed among intensive care unit (ICU) patients in hospital C between April and May 2019. Conclusions Quinolone-resistant C. striatum isolates showed a high prevalence of multidrug resistance. Point mutations in the QRDRs of gyrA conferred quinolone resistance to C. striatum, and several mutations in gyrA were newly found in this study. The great clonal diversity, high-level quinolone resistance and increased prevalence among patients susceptible to C. striatum isolates deserve more attention in the future. Moreover, more thorough investigation of the relationship between quinolone exposure and resistance evolution in C. striatum is necessary.

Practice of standardization of CLSI M45 A3 antimicrobial susceptibility testing of Infrequently Isolated or Fastidious Bacteria strains isolated from blood specimens in Guangdong Province 2017–2021

“…Corynebacterium striatum was generally resistant to ciprofloxacin (95.6%) in our study, which is consistent with the result reported by Wang Y. et al (2021) that 100.0% (410/410) of Corynebacterium striatum were resistant to ciprofloxacin. In our study, the resistance rate of Micrococcus luteus to erythromycin was 36.3%, and the resistance rate to clindamycin was 17.5%, which may indicate that a high number of infections caused by Micrococcus luteus resistant to ERY and CLI may fail therapy.…”

Antibioflm effects of extracellular matrix degradative agents on the biofilm of different strains of multi-drug resistant Corynebacterium striatum

“…In this study, almost all of the C. striatum strains investigated in this study were multidrug -resistant. They were only sensitive to vancomycin, linezolid and daptomycin, consistent with some previous global studies [ 5 , 16 , 17 ]. C. striatum isolates were mainly isolated from lower respiratory tract specimens (51.85%, 14/27).…”

In vitro Studies of Non-Diphtheriae Corynebacterium Isolates on Antimicrobial Susceptibilities, Drug Resistance Mechanisms, and Biofilm Formation Capabilities

“…Therefore, the QRDR at gyrA gene was amplified and sequenced as previously described. 8 , 28 , 31 , 32 In this study, the sequenced data of the gyrA gene from 42 ciprofloxacin-resistant isolates were compared to those from susceptible ones. Table 5 summarizes the associations between ciprofloxacin MICs and mutations in the gyrA QRDRs of ciprofloxacin-resistant isolates.…”