Multidrug-resistant conjugative plasmid carrying mphA confers increased antimicrobial resistance in Shigella.

Shigellosis remains a common gastrointestinal disease mostly in children < 5 years of age in developing countries. Azithromycin (AZM), a macrolide, is currently the first-line treatment for shigellosis in Bangladesh; ciprofloxacin (CIP) and ceftriaxone (CRO) are also used frequently. We aimed to evaluate the current epidemiology of antimicrobial resistance (AMR) and mechanism(s) of increasing macrolide resistance in Shigella in Bangladesh. A total of 2407 clinical isolates of Shigella from 2009 to 2016 were studied. Over the study period, Shigella sonnei was gradually increasing and become predominant (55%) over Shigella flexneri (36%) by 2016. We used CLSI-guided epidemiological cut-off value (ECV) for AZM in Shigella to set resistance breakpoints (zone-diameter ≤ 15 mm for S. flexneri and ≤ 11 mm for S. sonnei). Between 2009 and 2016, AZM resistance increased from 22% to approximately 60%, CIP resistance increased by 40%, and CRO resistance increased from zero to 15%. The mphA gene was the key macrolide resistance factor in Shigella; a 63MDa conjugative middle-range plasmid was harboring AZM and CRO resistance factors. Our findings show that, especially after 2014, there has been a rapid increase in resistance to the three most effective antibiotics. The rapid spread of macrolide (AZM) resistance genes among Shigella are driven by horizontal gene transfer rather than direct lineage.

Increasing trend of antibiotic resistance in Shigella in Bangladesh: a plasmid-mediated transfer of mphA macrolide resistance gene.

Shigellosis remains a common gastrointestinal disease mostly in children <5 years of age in developing countries. Azithromycin (AZM), a macrolide, is currently the first-line treatment for shigellosis in Bangladesh; ciprofloxacin (CIP) and ceftriaxone (CRO) are also used frequently. We aimed to evaluate the current epidemiology of antimicrobial resistance (AMR) and mechanism(s) of increasing macrolide resistance in Shigella in Bangladesh. A total of 2407 clinical isolates of Shigella from 2009 to 2016 were studied. Over the study period, Shigella sonnei was gradually increasing and become predominant (55%) over Shigella flexneri (36%) by 2016. We used CLSI-guided epidemiological cut-off value (ECV) for AZM in Shigella to set resistance breakpoints (zone-diameter ≤ 15 mm for S. flexneri and ≤ 11 mm for S. sonnei). Between 2009 and 2016, AZM resistance increased from 22% to approximately 60%, CIP resistance increased by 40%, and CRO resistance increased from zero to 15%. The mphA gene was the key macrolide resistance factor in Shigella; a 63MDa conjugative middle-range plasmid was harboring AZM and CRO resistance factors. Our findings show that, especially after 2014, there has been a rapid increase in resistance to the three most effective antibiotics. The rapid spread of macrolide (AZM) resistance genes among Shigella are driven by horizontal gene transfer rather than direct lineage.

Multiple Mechanisms Confer Resistance to Azithromycin in Shigella in Bangladesh: a Comprehensive Whole Genome-Based Approach.

Shigella is the second leading cause of diarrheal deaths worldwide. Azithromycin (AZM) is a potential treatment option for Shigella infection; however, the recent emergence of AZM resistance in Shigella threatens the current treatment strategy. Therefore, we conducted a comprehensive whole genome-based approach to identify the mechanism(s) of AZM resistance in Shigella. We performed antimicrobial susceptibility tests, polymerase chain reaction (PCR), Sanger (amplicon) sequencing, and whole genome-based bioinformatics approaches to conduct the study. Fifty-seven (38%) of the Shigella isolates examined were AZM resistant; Shigella sonnei exhibited the highest rate of resistance against AZM (80%). PCR amplification for 15 macrolide resistance genes (MRGs) followed by whole-genome analysis of 13 representative Shigella isolates identified two AZM-modifying genes, mph(A) (in all Shigella isolates resistant to AZM) and mph(E) (in 2 AZM-resistant Shigella isolates), as well as one 23S rRNA-methylating gene, erm(B) (41% of AZM-resistant Shigella isolates) and one efflux pump mediator gene, msr(E) [in the same two Shigella isolates that harbored the mph(E) gene]. This is the first report of msr(E) and mph(E) genes in Shigella. Moreover, we found that an IncFII-type plasmid predominates and can possess all four MRGs. We also detected two plasmid-borne resistance gene clusters: IS26-mph(A)-mrx(A)-mph(R)(A)-IS6100, which is linked to global dissemination of MRGs, and mph(E)-msr(E)-IS482-IS6, which is reported for the first time in Shigella. In conclusion, this study demonstrates that MRGs in association with pathogenic IS6 family insertion sequences generate resistance gene clusters that propagate through horizontal gene transfer (HGT) in Shigella. IMPORTANCE Shigella can frequently transform into a superbug due to uncontrolled and rogue administration of antibiotics and the emergence of HGT of antimicrobial resistance factors. The advent of AZM resistance in Shigella has become a serious concern in the treatment of shigellosis. However, there is an obvious scarcity of clinical data and research on genetic mechanisms that induce AZM resistance in Shigella, particularly in low- and middle-income countries. Therefore, this study is an approach to raise the alarm for the next lifeline. We show that two key MRGs [mph(A) and erm(B)] and the newly identified MRGs [mph(E) and msr(E)], with their origination in plasmid-borne pathogenic islands, are fundamental mechanisms of AZM resistance in Shigella in Bangladesh. Overall, this study predicts an abrupt decrease in the effectiveness of AZM against Shigella in the very near future and suggests prompt focus on seeking a more effective treatment alternative to AZM for shigellosis.

Draft Genome Sequences of Four Strains of Campylobacter jejuni Isolated from Patients with Axonal Variant of Guillain-Barré Syndrome in Bangladesh.

Four Campylobacter jejuni strains (Z191005RS, Z191005SS, Z201020RS, and Z201020SS) isolated from the axonal variant of Guillain-Barré syndrome (GBS) were sequenced using Illumina technology. The average genome size was from 1.61 to 1.63 gb, with a very high coverage ranging from 654× to 758×, which facilitates the possibility of rare variant calling.

Draft Genome Sequences of Multidrug-Resistant Shigella Strains Isolated from Diarrheal Patients in Bangladesh.

The emergence of multidrug-resistant (MDR) Shigella strains has impaired the efficacy of first-line antimicrobials and exacerbated diarrhea-associated morbidity and mortality worldwide. We report the draft genome sequences of 11 MDR Shigella strains isolated from the stool specimens of diarrheal patients in Bangladesh.

Draft Genome Sequences of Three Strains of Campylobacter jejuni Isolated from Patients with Guillain-Barré Syndrome in Bangladesh.

Campylobacter jejuni is the pathogen most commonly associated with Guillain-Barré syndrome (GBS). The present work describes the draft genome sequences of 3 C. jejuni strains, BD39, BD67, and BD75, isolated from stool specimens of patients with C. jejuni-triggered GBS using Illumina technologies.