Molecular clonality and detection of class 1 integron in multidrug-resistant Salmonella enterica isolates from animal and human in Iran

Prevalence of class 1 integron in Escherichia coli isolated from animal sources in Iran: a systematic review and meta-analysis

Background

Among the genetic elements, integrons may contribute to the widespread incidence and spreading of antibiotic resistance among Escherichia coli isolates. Accordingly, this review aims to investigate the prevalence of class 1 integron in E. coli isolated from animal sources in Iran.

Methods

This systematic literature search was performed from January 1, 2000 to the end of May 1, 2019.

Then, publications that met our inclusion criteria were selected for data extraction and analysis. Also, the quality of included studies was independently assessed by two researchers based on the Joanna Briggs Institute. Meta-analysis was performed by the Comprehensive Meta-Analysis (CMA) software using the random effects model, Cochran’s Q, and I² tests. Publication bias was estimated by funnel plot and Egger’s linear regression test.

Results

Based on inclusion criteria, five studies were included to meta-analysis. From those studies, the pooled prevalence of integrons was 33% (95% CI, 23.8–43.7%) ranging from 23.8 to 52.4%. There was a significant heterogeneity among the 5 studies (χ² = 11.73; p < 0.019; I² = 65.91%). Additionally, Begg’s and Egger’s tests were performed to quantitatively evaluate the publication biases. According to the results of Begg’s test (z = 1.22, p = 0.22) and Egger’s test (t = 3.03, p = 0.056), a significant publication bias was not observed.

Conclusions

Our finding revealed the relatively high prevalence of class 1 integrons among E. coli isolates. Moreover, there was a significant heterogeneity among studies and subgroup analysis also showed that there was no difference about prevalence of class 1 integrons among different sample source.

Molecular characterization of class 1, 2 and 3 integrons in clinical multi-drug resistant Klebsiella pneumoniae isolates

Background

The aim of this study was to characterize class 1,2 and 3 integrons in clinical MDR Klebsiella pneumoniae isolates in Kashan, Iran.

Methods

One hundred-eighty one Klebsiella pneumoniae were recovered from clinical specimens during November 2013 to October 2014. Antimicrobial susceptibility patterns were determined by disk diffusion method according to the Clinical and Laboratory Standards Institute (CLSI) guidelines for detection of MDR strains. Of the 181 Klebsiella pneumoniae, 146 (80.7%) of isolates were isolated from nosocomial infected patients and 150 (82.9%) identified as MDR isolates. The PCR amplification was used to show presence of class 1, 2 and 3 integrons among MDR strains. The PCR method and sequencing were used for evaluation of cassette content of integrons.

Results

Of the MDR K. pneumoniae isolates, 150 (100%) and 55 (36.7%) carried intI1 and intI2 genes, respectively. None of the MDR Klebsiella pneumoniae isolates carried class 3 integrons. Amplification of conserved segment (CS) of class 1 and class 2 integrons revealed 10 different arrays including: No. cassette; dfrA5, dfrA30; aadA2; aadA2, dfrA12; dfrA17, aadA5, aadA4; dfrA5, dfrA30, aadA2; dfrA5, dfrA30, aadA2, dfrA12, dfrA5, dfrA30, dfrA17, aadA5, aadA4; aadA2, aadA2, dfrA12; dfrA5, dfrA30, aadA2, aadA2, dfrA12 and 4 arrays including: No. cassette; aadA1; dfrA1-sat1; aadA1, dfrA1-sat1, respectively.

Conclusions

The finding of present study revealed a high prevalence of integrons especially class 1 among MDR K. pneumoniae isolates from nosocomial infections in Kashan, which led to rapid extension of MDR strains.

Characterization of the resistance class 1 integrons in Staphylococcus aureus isolates from milk of lactating dairy cattle in Northwestern China

Background

Integrons are mobile DNA elements and they have an important role in acquisition and dissemination of antimicrobial resistance genes. However, there are limited data available on integrons of Staphylococcus aureus (S. aureus) from bovine mastitis, especially from Chinese dairy cows. To address this knowledge gap, bovine mastitis-inducing S. aureus isolates were investigated for the presence of integrons as well as characterization of gene cassettes. Integrons were detected using PCR reactions and then further characterized by a restriction fragment-length polymorphism analysis and amplicon sequencing.

Results

All 121 S. aureus isolates carried the class 1 integrase gene intI1, with no intI2 and intI3 genes detected. One hundred and three isolates were positive for the presence of 12 resistance genes, either alone or in combination with other gene cassettes. These resistance genes encoded resistance to trimethoprim (dhfrV, dfrA1, dfrA12), aminoglycosides (aadA1, aadA5, aadA4, aadA24, aacA4, aadA2, aadB), chloramphenicol (cmlA6) and quaternary ammonium compound (qacH) and were organized into 11 different gene cassettes arrangements (A-K). The gene cassette arrays dfrA1-aadA1 (D, 44.6%), aadA2 (K, 31.4%), dfrA12-orfX2-aadA2 (G, 27.3%) and aadA1 (A, 25.6%) were most prevalent. Furthermore, 74 isolates contained combinations of 2 to 4 gene cassette arrays. Finally, all of the integron/cassettes-positive isolates were resistant to aminoglycoside antibiotics.

Conclusions

This is the first study on the integrons and gene cassette arrays in S. aureus isolates from milk of mastitic cows from Northwestern China and provide the evidence for class 1 integron as possible antibiotic resistance determinants on dairy farms.