ESBL-Producing and Macrolide-Resistant Shigella sonnei Infections among Men Who Have Sex with Men, England, 2015

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.

Healthcare providers' knowledge and clinical practice surrounding shigellosis - DocStyles Survey, 2020

BACKGROUND

Shigellosis is an acute diarrheal disease transmitted through contaminated food, water, objects, poor hand hygiene, or sexual activity. Healthcare providers (HCP) may not be aware of the multiple routes of Shigella transmission, populations at increased risk, or importance of antibiotic susceptibility testing (AST). This study assessed HCP knowledge and clinical practices regarding shigellosis and antibiotic resistance.

METHODS

Porter Novelli Public Services administered a web-based survey (Fall DocStyles 2020) to HCP in the United States. Pediatricians, primary care physicians, nurse practitioners, and physician assistants completed questions about knowledge and clinical practice of acute diarrhea and shigellosis.

RESULTS

Of 2196 HCP contacted, 1503 responded (68% response rate). Most identified contaminated food (85%) and water (79%) as routes of Shigella transmission; fewer recognized person-to-person contact (40%) and sexual activity (18%). Men who have sex with men (MSM) were identified as being at risk for shigellosis by 35% of respondents. Most reported counseling patients to wash hands (86%) and avoid food preparation (77%) when ill with shigellosis; 29% reported recommending avoiding sex. Many HCP reported treating shigellosis empirically with ciprofloxacin (62%) and azithromycin (32%), and 29% reported using AST to guide treatment.

CONCLUSIONS

We identified several gaps in shigellosis knowledge among HCP including MSM as a risk group, person-to-person transmission, and appropriate antibiotic use. Improving HCP education could prevent the spread of shigellosis, including drug-resistant infections, among vulnerable populations.

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.

British Association of Sexual Health and HIV (BASHH) United Kingdom national guideline for the management of sexually transmitted enteric infections 2023

This is the first British Association of Sexual Health and HIV (BASHH) national guideline for the management of sexually transmitted enteric infections (STEI). This guideline is primarily aimed for level 3 sexual health clinics; however, it may also be applicable to other settings such as primary care or other hospital departments where individuals with STEI may present. This guideline makes recommendations on testing, management, partner notification and public health control of STEI.

Antimicrobial resistance in sexually transmitted Shigella in men who have sex with men: A systematic review

BACKGROUND

Outbreaks of sexually transmitted Shigella flexneri and Shigella sonnei in men who have sex with men (MSM) are a major public health issue. While most cases can be managed conservatively, a minority require antimicrobial treatment. Recent reports have highlighted increasing antimicrobial resistant (AMR) strains of Shigella spp. in men who have sex with men. We aimed to systematically review antimicrobial resistance (and decreased antimicrobial sensitivity) in sexually transmitted shigella in men who have sex with men, focussing on macrolides, quinolones, and third generation cephalosporins.

METHODS

We systematically searched 4 bibliographical databases (EMBASE, medline, EMCARE and CINAHL) from January 2011 to November 2021. We used a 2-stage process to assess eligibility: the primary author conducted an initial screen and then 3 authors conducted independent full-text reviews to determine the final eligible manuscripts. We only included manuscripts in English which included men who have sex with men with sexually transmitted shigella where data on antimicrobial resistance was available.

RESULTS

Thirty-nine manuscripts met the inclusion criteria. A majority of the manuscripts (N = 34) described reduced susceptibility or antimicrobial resistant to macrolides, quinolones and third generation cephalosporins in circulating strains of shigella within sexual networks of men who have sex with men. Extensively drug resistant outbreaks of shigella in men who have sex with men have been reported containing genetic markers of ceftriaxone resistance (e.g. BlaCTX-M27) where isolates also contained markers of reduced susceptibility, and antimicrobial resistant to macrolides and quinolones.

CONCLUSION

There is little role for macrolides, quinolones or third generation cephalosporins in the management of sexually transmitted shigella in men who have sex with men. More research is needed to develop novel strategies for shigella control in men who have sex with men, as antimicrobial options are diminishing.

Increasing trend of antimicrobial resistance in Shigella associated with MSM transmission in Barcelona, 2020-21: outbreak of XRD Shigella sonnei and dissemination of ESBL-producing Shigella flexneri

BACKGROUND

Several countries have recently reported the detection of ESBL-producing Shigella sonnei associated with transmission among MSM. In a previous study by our group, 2.8% of Shigella spp. obtained from MSM in Barcelona between 2015 and 2019 were ESBL producers.

OBJECTIVES

To describe and characterize the emerging ESBL-producing Shigella spp. associated with sexual transmission among MSM detected from 2020 to 2021 in Barcelona, elucidating their connectivity with contemporaneous ESBL-producing Shigella spp. from other countries.

RESULTS

From 2020 to 2021, we identified that among MSM, 68% of S. sonnei were XDR harbouring blaCTX-M-27 and 14% of Shigella flexneri were MDR harbouring blaCTX-M-27. WGS analysis showed that the ESBL-producing S. sonnei were part of a monophyletic cluster, which included isolates responsible for the prolonged outbreak occurring in the UK. Our data also reveal the first emergence and clonal dissemination of ESBL-producing and fluoroquinolone-resistant S. flexneri 2a among MSM.

CONCLUSIONS

We report an increasing trend of antimicrobial resistance in Shigella spp. among MSM in Barcelona since 2021, mainly as a consequence of the dissemination of XDR ESBL-producing S. sonnei, previously reported in the UK. These results highlight the importance of international collaborative surveillance of MDR/XDR S. sonnei and S. flexneri for rapid identification of their emergence and the prevention of the transmission of these pathogens.

Emergence of extensively drug-resistant and multidrug-resistant Shigella flexneri serotype 2a associated with sexual transmission among gay, bisexual, and other men who have sex with men, in England: a descriptive epidemiological study

BACKGROUND

Shigellosis, also known as bacillary dysentery, is caused by Shigella spp that spread through fecal-oral contact and was traditionally associated with international travel in England. However, sexual transmission of Shigella flexneri and Shigella sonnei among gay, bisexual, and other men who have sex with men (MSM) is now common. In September, 2021, emergence of extensively drug-resistant (XDR) S sonnei harbouring plasmid-encoded bla_CTX-M-27 raised concerns over further spread of this extended-spectrum β-lactamase-producing gene. Using national surveillance in England, we identified and characterised isolates of S flexneri harbouring bla_CTX-M-27.

METHODS

In this epidemiological study, we identified and phylogenetically characterised S flexneri isolates harbouring bla_CTX-M-27 that were referred to the Gastrointestinal Bacterial Reference Unit (GBRU) at the UK Health Security Agency. All isolates referred to the GBRU undergo whole-genome sequencing, enabling antimicrobial resistance determination using genetic markers. Cases were defined as individuals diagnosed with S flexneri harbouring bla_CTX-M-27 in England, with a specimen date between Sept 1, 2015, and June 12, 2022, who were phylogenetically confirmed as part of two t10 (approximately ten single nucleotide polymorphisms) clusters. Long-read sequencing elucidated the genomic location of bla_CTX-M-27. Laboratory data, integrated with available demographic and clinical information from patient questionnaires, were summarised using descriptive statistics.

FINDINGS

A sustained increase in cases of S flexneri harbouring bla_CTX-M-27 (n=26) occurred from September, 2021, having been sporadically reported (n=11) in the preceding 6 years. bla_CTX-M-27 acquisition events within S flexneri 2a established an XDR paraphyletic (n=8) cluster and a multidrug-resistant monophyletic (n=18) cluster. Cases were among adult male individuals (median age 37 years [IQR 31-46]) and, of the 13 individuals who completed a patient questionnaire, ten (77%) identified as MSM. Antimicrobial treatment was received by seven (54%) of 13 individuals, and four (31%) individuals were admitted to hospital. The IncFII plasmids harbouring bla_CTX-M-27 showed high similarity to the XDR S sonnei outbreak plasmid, with 82% and 99% nucleotide similarity between the cluster plasmids and the XDR S sonnei outbreak plasmid.

INTERPRETATION

We report emergence of XDR and multidrug-resistant S flexneri 2a harbouring bla_CTX-M-27 among MSM in England. Epidemiological and plasmid similarities with the XDR S sonnei outbreak support horizontal acquisition events, emphasising the importance of mobilisable antimicrobial resistance and the need for genomic-based surveillance.

FUNDING

National Institute for Health and Care Research Health Protection Research Unit in Gastrointestinal Infections at the University of Liverpool in partnership with the UK Health Security Agency.

Molecular detection and characterization of Shigella spp. harboring extended-spectrum β-lactamase genes in children with diarrhea in northwest Iran

Shigellosis is one of the acute bowel infections and remains a serious public health problem in resource-poor countries. The present study aimed to survey the distribution of extended-spectrum β-lactamase (ESBL)-producing Shigella strains isolated from patients with diarrhea in northwest Iran. In the present cross-sectional study, from January 2019 to December 2020, 1280 fecal samples were collected from children with diarrhea in Ardabil, Iran. Multiplex PCR assay was applied for the presence of ipaH, invC, wbgZ, rfpB, and rfc genes to detect Shigella spp., Shigella sonnei, Shigella dysenteriae, Shigella flexneri, and Shigella boydii, respectively. Phenotypic detection of ESBL-producing isolates was carried out using the Double Disc Test (DDT). The frequency of main ESBL encoding genes including bla_CTX-M, bla_SHV, and bla_TEM was detected using multiplex PCR. The genetic similarity of S. sonnei isolates was determined using ERIC PCR. A total of 49 Shigella isolates (3.8%; 49/1280) including 42 (85.7%) S. sonnei, 5 (10.2%) S. flexneri, and 2 (4%) S. dysenteriae were identified. S. boydii was not detected in any fecal samples. ESBLs were produced by 10.2% of Shigella spp. including 3 S. sonnei, 1 S. flexneri, and 1 S. dysenteriae. The ESBL encoding genes include bla_CTX-M and bla_TEM found in 65.3% and 61.2% of isolates, respectively. bla_SHV gene was not detected in any isolates. The ERIC-PCR profiles allowed the differentiation of 42 S. sonnei strains into 6 clusters. Our study revealed a high frequency of ESBL-encoding genes among Shigella spp. in northwest Iran. The high prevalence of S. sonnei harboring ESBL genes, in the present work, is the main challenge for dysentery treatment, and this concern justifies the need for effective and regular monitoring of antibiotic usage among patients.

Shigella is common in symptomatic and asymptomatic men who have sex with men visiting a sexual health clinic in Amsterdam

INTRODUCTION

Shigellosis is a reportable infectious disease. It can present as a severe bloody diarrhoea but is often asymptomatic. Shigella can be sexually transmissible. We performed a study among symptomatic and asymptomatic men who have sex with men (MSM) to assess the prevalence of Shigella, Salmonella and Campylobacter.

METHODS

From March to June 2020, MSM attending the Amsterdam centre for sexual health were consecutively included. Predefined minimal numbers of inclusion of 150, 100 and 50 were determined, respectively, for MSM who reported no diarrhoea, diarrhoea during last month or diarrhoea on the day of visit to clinic. Anal samples were tested for the presence of Shigella, Salmonella and Campylobacter. During the same period, the frequency of these bacteria was assessed in routinely tested samples requested by general physicians or nursing home physicians. Characteristics of included MSM were compared between the men with different diarrhoea anamnesis, and the prevalence of shigellosis was estimated in each group.

RESULTS

We included 212 MSM without diarrhoea, 109 MSM who recently had diarrhoea and 68 MSM who reported diarrhoea on the day of clinic visit. Thirteen (3.3%, 95% CI 1.7% to 5.6%) MSM were infected with Shigella, none with Salmonella and 7 (1.8%, 95% CI 0.7% to 3.7%) with Campylobacter. Shigella prevalence was 2.8% (95% CI 1.0% to 6.1%) in asymptomatic men, 3.7% (95% CI 1.0% to 9.1%) in men who recently had diarrhoea and 4.4% (95% CI 0.9% to 12.4%) in men with current diarrhoea (p=0.799). Shigella was more frequently found in MSM who had used pre-exposure prophylaxis (PrEP) in the preceding 3 months (10/151), compared with those not having used PrEP (2/146) or being HIV positive (1/75) (p=0.038). Shigella was significantly more often detected among MSM compared with routinely obtained faecal samples being 11/770 (1.4%) (p=0.031).

CONCLUSION

Shigella infections are relatively common in both symptomatic and asymptomatic MSM. Future studies should focus on the risk of onward transmission via asymptomatic persons. Samenvatting Introductie Shigellose is een meldingsplichtige infectieziekte. Het kan zich presenteren als een ernstige bloederige diarree, maar is vaak asymptomatisch. Shigella kan seksueel overdraagbaar zijn. We hebben een onderzoek uitgevoerd onder symptomatische en asymptomatische mannen die seks hebben met mannen (MSM) om de prevalentie van Shigella, Salmonella en Campylobacter te bepalen. Methoden Van maart tot juni 2020 werden achtereenvolgens MSM van het Amsterdamse centrum voor seksuele gezondheid opgenomen. Vooraf gedefinieerde minimale aantallen van inclusie van respectievelijk 150, 100 en 50 waren bepaald voor MSM die geen diarree, diarree in de afgelopen maand of diarree op de dag van bezoek aan de kliniek meldden. Anale monsters werden getest op de aanwezigheid van Shigella, Salmonella en Campylobacter. In dezelfde periode werd de frequentie van deze bacteriën bepaald in routinematig geteste monsters aangevraagd door huisartsen of verpleeghuisartsen. Kenmerken van geïncludeerde MSM werden vergeleken tussen mannen met verschillende diarree anamnese, en de prevalentie van shigellose werd in elke groep geschat. Resultaten We includeerden 212 MSM zonder diarree, 109 MSM die onlangs diarree hadden en 68 MSM die diarree meldden op de dag van het bezoek aan de kliniek. Dertien (3,3%, 95% CI 1,7-5,6%) MSM waren geïnfecteerd met Shigella, geen enkele met Salmonella, en 7 (1,8%, 95% CI 0,7-3,7%) met Campylobacter. De prevalentie van Shigella was 2,8% (95%CI 1,0-6,1%) bij asymptomatische mannen, 3,7% (95%CI 1,0-9,1%) bij mannen die recent diarree hadden en 4,4% (95%CI 0,9-12,4%) bij mannen met huidige diarree (P=0,799). Shigella werd vaker gevonden bij MSM die in de voorgaande drie maanden (10/151) PrEP hadden gebruikt dan bij mensen die geen PrEP hadden gebruikt (2/146) of hiv-positief waren (1/75) (p=0,038). Shigella werd significant vaker gedetecteerd bij MSM in vergelijking met routinematig verkregen fecale monsters, namelijk 11/770 (1,4%) (p=0,031). Conclusie Shigella infecties komen relatief vaak voor bij zowel symptomatische als asymptomatische MSM. Toekomstige studies moeten zich richten op het risico van verdere overdracht via asymptomatische personen.

A Shigella sonnei clone with extensive drug resistance associated with waterborne outbreaks in China

Antimicrobial resistance of Shigella sonnei has become a global concern. Here, we report a phylogenetic group of S. sonnei with extensive drug resistance, including a combination of multidrug resistance, coresistance to ceftriaxone and azithromycin (cef^Razi^R), reduced susceptibility to fluoroquinolones, and even colistin resistance (col^R). This distinct clone caused six waterborne shigellosis outbreaks in China from 2015 to 2020. We collect 155 outbreak isolates and 152 sporadic isolates. The cef^Razi^R isolates, including outbreak strains, are mainly distributed in a distinct clade located in global Lineage III. The outbreak strains form a recently derived monophyletic group that may have emerged circa 2010. The cef^Razi^R and col^R phenotypes are attributed to the acquisition of different plasmids, particularly the IncB/O/K/Z plasmid coharboring the bla_CTX-M-14, mphA, aac(3)-IId, dfrA17, aadA5, and sul1 genes and the IncI2 plasmid with an mcr-1 gene. Genetic analyses identify 92 accessory genes and 60 single-nucleotide polymorphisms associated with the cef^Razi^R phenotype. Surveillance of this clone is required to determine its dissemination and threat to global public health.

MDR Shigella sonnei in Spain: an ever-evolving emerging threat?

Background

Seven CTX-M-27-producing Shigella sonnei strains were isolated at the University Hospital Virgen del Rocío (Seville, Spain) microbiology service from October to November 2021.

Objectives

To offer extensive information on the microbiological and molecular epidemiology results of the seven S. sonnei isolates and compare them with other previously documented CTX-M-27-producing S. sonnei associated with MSM transmission.

Methods

S. sonnei isolated from stool samples of patients with acute diarrhoea were identified through biochemical and serological typing. Whole characterization of the seven isolates was performed by sequencing with MinION Mk1C followed by genomic and molecular analysis.

Results

All the isolates were resistant to penicillins, cephalosporins, fluoroquinolones, cotrimoxazole and azithromycin. Sequencing showed the presence of several resistance determinants, outstanding bla_CTX-M-27, azithromycin resistance genes [ermB and mph(A)], qnrB19 and mutations in the QRDRs. All isolates belonged to the same hierarchical clustering of cgMLST (HierCC) with five allele distance (HC5) scheme v1 from EnteroBase. However, they presented differences in plasmid composition, with all seven isolates harbouring IncFII, IncB/O/K/Z and ColE1-like while SH2, SH6 and SH7 had IncFIB only. Our isolates were closely related to others from Spain (HC5; 98748), Australia (HC5; 98748) and the UK (HC5; 98748), which were also associated with MSM transmission. Nevertheless, the structure of the non-chromosomal genetic elements and the genetic context of bla_CTX-M-27 presented a certain variability compared with isolates from other countries and among them.

Conclusions

This study confirms the emergence of CTX-M-27-producing S. sonnei (ST152) associated with MSM transmission in Spain, adding it to the Europe outbreak list and reinforcing the necessity of active surveillance and control of this high-risk clone.

Characterization of Extended-Spectrum β-Lactamase-Producing Shigella sonnei in Spain: Expanding the Geographic Distribution of Sequence Type 152/CTX-M-27 Clone

We describe the first occurrence in Spain of community cases of CTX-M-27-producing Shigella sonnei sequence type 152 (ST152), resistant to quinolones and azithromycin. The cases included adult males and also one pediatric case. The isolates were clustered together with an Australian isolate and differed from other outbreak-causing strains in England by more than 50 alleles. They carried the bla_CTX-M-27 gene on an 83-Kb F2:A-:B- plasmid, similar to that found in a British isolate.

Clinical and Genomic Investigation of an International Ceftriaxone- and Azithromycin-Resistant Shigella sonnei Cluster among Men Who Have Sex with Men, Montréal, Canada 2017-2019

Multidrug-resistant (MDR) Shigella sonnei have become prevalent among men who have sex with men and have become a global public health concern. From June 2017 to April 2019, 32 men were infected with MDR S. sonnei acquired locally, in Montréal, which was suggestive of an outbreak. Antimicrobial susceptibility testing, whole-genome sequencing (WGS), phylogenetic analysis, antimicrobial resistance and virulence characterization, and association to international clusters were performed. The outbreak strain was ceftriaxone- and azithromycin-resistant due to the acquisition of bla_CTX-M-27, and mphA and ermB genes, respectively, with reduced susceptibility to ciprofloxacin due to a single point mutation (gyrA S83L). One out of 27 patients treated with a fluoroquinolone experienced microbiological failure. Epidemiological evidence first supported by a rare unique MDR Shigella sonnei documented only in men in 2017 followed by similar pulsed-field gel electrophoresis profiles was confirmed by WGS. A core genome high-quality single-nucleotide variant (hqSNV)-based phylogeny found a median of 6 hqSNV differences among isolates. Virulence gene content was investigated, but no Shiga toxins were detected. An international cluster of highly related isolates was identified (PDS000019750.208) and belonged to the 3.7.29.1.4.1 S. sonnei genotype (Global III VN2.KH1.Aus). Genomic analysis revealed that this Montréal cluster was connected to other documented outbreaks in Australia, the United States, and the United Kingdom. This study highlights the urgent need for public health measures to focus on the prevention and the early detection of S. sonnei, since global transmission patterns of MDR strains is concerning and few antimicrobial treatment options are available.

IMPORTANCEShigella sonnei, an important foodborne pathogen, recently became a frequent sexually transmitted agent involved in large and persistent outbreaks globally among men who have sex with men. Most strains also harbor several multidrug-resistant (MDR) determinants of particular concern. This study characterizes an outbreak strain at the source of an important MDR cluster identified in Montréal in 2017. Associations were made to many high-profile international outbreaks, and the causative S. sonnei lineage of these clusters was identified, which was not evident in past reports. The worldwide occurrence of this strain is of concern since treatment with antimicrobials like ceftriaxone and azithromycin may not be effective, and rare microbiological failures have been documented in patients treated with ciprofloxacin. Our investigation highlights the threats of Shigella spp. infection and the necessity for antimicrobial susceptibility monitoring in order to mitigate S. sonnei’s impact on public health and to avoid transmission to other at-risk communities.

Enteric Infections in Men Who Have Sex With Men

BACKGROUND

Enteric pathogens are often associated with exposure to food, water, animals, and feces from infected individuals. However, in sexual networks of men who have sex with men (MSM), transmission of enteric pathogens may occur during direct or indirect oral-anal contact.

METHODS

We performed a scoping review of the literature for studies prior to July 2019 with key terms for gastrointestinal syndromes ("proctitis," "enteritis," "proctocolitis"), enteric pathogens or sexually transmitted infections (STIs), and outbreaks using multiple electronic databases.

RESULTS

We identified 5861 records through database searches, bibliography reviews, and keyword searches, of which 117 references were included in the pathogen-specific reviews.

CONCLUSIONS

The strength of observational data describing enteric pathogens in MSM and possible sexual transmission of enteric pathogens varies by pathogen; however, a robust body of literature describes the sexual transmission of Campylobacter, Giardia lamblia, and Shigella (particularly antimicrobial-resistant strains) in sexual networks of MSM. Providers are encouraged to consider enteritis or proctocolitis in MSM as possibly having been sexually transmitted and encourage targeted STI testing. Risk/harm reduction and prevention messages should also be incorporated, though there is an acknowledged paucity of evidence with regards to effective strategies. Further research is needed to understand the transmission and prevention of enteric pathogens in MSM.

Emergence of novel strains of Shigella flexneri associated with sexual transmission in adult men in England, 2019-2020

National surveillance of shigellosis in England revealed an increase in sexually transmitted Shigella flexneri in adult males in 2019 that persisted throughout 2020. We observed a resurgence of azithromycin-resistant S. flexneri serotype 3a, and the emergence of two novel multidrug-resistant clades of S. flexneri 2a and S. flexneri 1b.

Prevalence of Gastrointestinal Pathogens Detected by Multiplex Polymerase Chain Reaction in a Prospective Cohort of Men Who Have Sex With Men Taking Human Immunodeficiency Virus Preexposure Prophylaxis-New York City, 2019-2020

Multiplex polymerase chain reaction testing for gastrointestinal pathogens was performed on a longitudinal cohort of 110 men who have sex with men taking human immunodeficiency virus preexposure prophylaxis. At least 1 pathogen was detected among 50 (45%) participants, with some participants testing positive for the same pathogen on multiple consecutive visits over a period of months.

Acquisition and loss of CTX-M plasmids in Shigella species associated with MSM transmission in the UK

Shigellosis in men who have sex with men (MSM) is caused by multidrug resistant Shigellae, exhibiting resistance to antimicrobials including azithromycin, ciprofloxacin and more recently the third-generation cephalosporins. We sequenced four bla_CTX-M-27-positive MSM Shigella isolates (2018–20) using Oxford Nanopore Technologies; three S. sonnei (identified as two MSM clade 2, one MSM clade 5) and one S. flexneri 3a, to explore AMR context. All S. sonnei isolates harboured Tn7/Int2 chromosomal integrons, whereas S. flexneri 3a contained the Shigella Resistance Locus. All strains harboured IncFII pKSR100-like plasmids (67-83kbp); where present bla_CTX-M-27 was located on these plasmids flanked by IS26 and IS903B, however bla_CTX-M-27 was lost in S. flexneri 3a during storage between Illumina and Nanopore sequencing. IncFII AMR regions were mosaic and likely reorganised by IS26; three of the four plasmids contained azithromycin-resistance genes erm(B) and mph(A) and one harboured the pKSR100 integron. Additionally, all S. sonnei isolates possessed a large IncB/O/K/Z plasmid, two of which carried aph(3’)-Ib/aph(6)-Id/sul2 and tet(A). Monitoring the transmission of mobile genetic elements with co-located AMR determinants is necessary to inform empirical treatment guidance and clinical management of MSM-associated shigellosis.

Potential for Phages in the Treatment of Bacterial Sexually Transmitted Infections

Bacterial sexually transmitted infections (BSTIs) are becoming increasingly significant with the approach of a post-antibiotic era. While treatment options dwindle, the transmission of many notable BSTIs, including Neisseria gonorrhoeae, Chlamydia trachomatis, and Treponema pallidum, continues to increase. Bacteriophage therapy has been utilized in Poland, Russia and Georgia in the treatment of bacterial illnesses, but not in the treatment of bacterial sexually transmitted infections. With the ever-increasing likelihood of antibiotic resistance prevailing and the continuous transmission of BSTIs, alternative treatments must be explored. This paper discusses the potentiality and practicality of phage therapy to treat BSTIs, including Neisseria gonorrhoeae, Chlamydia trachomatis, Treponema pallidum, Streptococcus agalactiae, Haemophilus ducreyi, Calymmatobacterium granulomatis, Mycoplasma genitalium, Ureaplasma parvum, Ureaplasma urealyticum, Shigella flexneri and Shigella sonnei. The challenges associated with the potential for phage in treatments vary for each bacterial sexually transmitted infection. Phage availability, bacterial structure and bacterial growth may impact the potential success of future phage treatments. Additional research is needed before BSTIs can be successfully clinically treated with phage therapy or phage-derived enzymes.

Circulation of multi-drug-resistant Shigella sonnei and Shigella flexneri among men who have sex with men in Barcelona, Spain, 2015-2019

BACKGROUND

In high-income countries, shigellosis is mainly found in travellers to high-risk regions or in men who have sex with men (MSM). This study investigated the genomic characteristics and the features of antimicrobial resistance of MSM-associated Shigella flexneri and Shigella sonnei circulating in Barcelona, Spain, elucidating their connectivity with contemporaneous Shigella spp. from other countries.

METHODS

Antimicrobial susceptibility, whole-genome sequencing, genomic characterization and phylogenetic analysis were performed in MSM-associated Shigella spp. recovered from 2015 to 2019. Reference genomes of MSM-associated Shigella spp. were included for contextualization and to determine their connection with international outbreaks.

RESULTS

In total, 44 S. flexneri and 26 S. sonnei were identified among MSM. Overall, 80% showed resistance to azithromycin, 65.7% showed resistance to trimethoprim-sulphamethoxazole and 32.8% showed resistance to ciprofloxacin; 27.1% were resistant to all three antimicrobials. mphA and/or ermB, and qnrS and mutations in the quinolone resistance determining regions were found in the azithromycin- and ciprofloxacin-resistant isolates, respectively. Additionally, two isolates carried bla_CTX-M-27. Single-nucleotide-polymorphism-based analysis revealed that the isolates were organized into different lineages, most of which were closely related to dominant MSM-associated lineages described previously in the UK and Australia.

CONCLUSIONS

This study investigated the circulation of lineages of S. flexneri and S. sonnei among MSM in Spain that were mainly resistant to first-/second-line oral treatments, and closely related to dominant MSM-associated lineages described previously in the UK and Australia. These data reinforce the urgent need for the implementation of public health measures focusing on the early detection and prevention of transmission of this emerging pathogen, which is contributing to the antimicrobial resistance crisis in sexually transmitted infections.

Brazilian Protocol for Sexually Transmitted Infections, 2020: sexually transmitted enteric infections

The sexually transmitted enteric infections topic is one of the chapters of the Clinical Protocol and Therapeutic Guidelines for Comprehensive Care for People with Sexually Transmitted Infections, published by the Brazilian Ministry of Health in 2020. The document was developed based on scientific evidence and validated in discussions with specialists. This article presents epidemiological and clinical aspects of these infections and guidance for service managers on their programmatic and operational management. The aim is to assist health professionals with screening, diagnosis, and treatment of people with sexually transmitted enteric infections and their sexual partners, in addition to supporting strategies for their surveillance, prevention, and control. The incidence of anorectal sexually transmitted infections has increased over the last years, mainly due to the increase in the practice of unprotected receptive anal sexual intercourse.

Target Product Profile and Development Path for Shigellosis Treatment with Antibacterials

Enteric infection with Shigella spp. can lead to symptoms ranging from acute watery diarrhea to sudden, severe dysentery. Approximately 212 000 diarrheal deaths annually are attributed to Shigella with a disproportionate impact in low-resource countries. The impact in under-resourced countries was illustrated by a reanalysis of the Global Enteric Multicenter Study which found that Shigella was the leading pathogen associated with moderate-to severe diarrhea in children under 5 years old. While recent studies have highlighted the burden of the disease, there has been a concurrent reduction in therapeutic options for the treatment of shigellosis as drug resistant strains increase in prevalence. In addition, increasing reports of drug resistant shigellosis cases in the men who have sex with men community confirm that the impact is not limited to low-resource countries. Despite the urgent need for new treatments, a target product profile (TPP) has not been established, and there is no clear development path for antibacterial treatments. To address this troubling concern, this manuscript describes a TPP for antishigellosis small molecule therapeutics and a development path that integrates currently available preclinical and clinical models of Shigella infection.

Global population structure and genotyping framework for genomic surveillance of the major dysentery pathogen, Shigella sonnei

Shigella sonnei is the most common agent of shigellosis in high-income countries, and causes a significant disease burden in low- and middle-income countries. Antimicrobial resistance is increasingly common in all settings. Whole genome sequencing (WGS) is increasingly utilised for S. sonnei outbreak investigation and surveillance, but comparison of data between studies and labs is challenging. Here, we present a genomic framework and genotyping scheme for S. sonnei to efficiently identify genotype and resistance determinants from WGS data. The scheme is implemented in the software package Mykrobe and tested on thousands of genomes. Applying this approach to analyse >4,000 S. sonnei isolates sequenced in public health labs in three countries identified several common genotypes associated with increased rates of ciprofloxacin resistance and azithromycin resistance, confirming intercontinental spread of highly-resistant S. sonnei clones and demonstrating the genomic framework can facilitate monitoring the spread of resistant clones, including those that have recently emerged, at local and global scales.

[Brazilian Protocol for Sexually Transmitted Infections 2020: sexually transmitted enteric infections]

The topic of sexually transmitted enteric infections is one of the chapters of the Clinical Protocol and Therapeutic Guidelines for Comprehensive Care for People with Sexually Transmitted Infections, published by the Brazilian Ministry of Health in 2020. The document was developed based on scientific evidence and validated in discussions with specialists. This article presents epidemiological and clinical aspects related to these infections, as well as guidance for service managers on their programmatic and operational management. The aim is to assist health professionals with screening, diagnosis and treatment of people with sexually transmitted enteric infections and their sexual partners, in addition to supporting strategies for their surveillance, prevention and control.

Utility of whole-genome sequencing during an investigation of multiple foodborne outbreaks of Shigella sonnei

In April 2018, Public Health England was notified of cases of Shigella sonnei who had eaten food from three different catering outlets in England. The outbreaks were initially investigated as separate events, but whole-genome sequencing (WGS) showed they were caused by the same strain. The investigation included analyses of epidemiological data, the food chain and microbiological examination of food samples. WGS was used to determine the phylogenetic relatedness and antimicrobial resistance profile of the outbreak strain. Ultimately, 33 cases were linked to this outbreak; the majority had eaten food from seven outlets specialising in Indian or Middle Eastern cuisine. Five outlets were linked to two or more cases, all of which used fresh coriander although a shared supplier was not identified. An investigation at one of the venues recorded that 86% of cases reported eating dishes with coriander as an ingredient or garnish. Four cases were admitted to hospital and one had evidence of treatment failure with ciprofloxacin. Phylogenetic analysis showed that the outbreak strain was part of a wider multidrug-resistant clade associated with travel to Pakistan. Poor hygiene practices during cultivation, distribution or preparation of fresh produce are likely contributing factors.

High carriage of ESBL-producing Enterobacteriaceae associated with sexual activity among men who have sex with men

BACKGROUND

Extended-spectrum β-lactamase Enterobacteriaceae (ESBL-E) may be sexually transmitted. Men who have sex with men (MSM) have different sexual behaviour than the general population, and thus may be at risk for ESBL-E carriage. This study determined the prevalence of ESBL-E carriage and its association with sexual behaviour among MSM in Amsterdam, The Netherlands.

MATERIALS AND METHODS

In total, 583 HIV-positive and HIV-negative MSM from the Amsterdam Cohort Study were screened for rectal ESBL-E carriage between April and December 2018. Participants completed a self-administered questionnaire on (sexual) behaviour and risk factors for antimicrobial resistance. The proportion of the study population with ESBL-E carriage was compared by number of sexual partners using logistic regression, and across clusters of sexual behaviours with steady and casual partners, separately, using latent class analyses; all results were adjusted for recent use of antibiotics, travel and hospitalization.

RESULTS

Overall, 16.3% [95% confidence interval (CI) 13.4-19.5] of the study population tested positive for ESBL-E. The odds of ESBL-E carriage increased as number of sexual partners increased [adjusted odds ratio per ln(partner+1), 1.57, 95% CI 1.26-1.94; P<0.001]. There was no association between ESBL-E carriage and sexual behaviour with steady partner(s). Compared with participants in the 'no sex with casual partner(s)' cluster, adjusted odds of being ESBL-E positive were 2.95-fold higher (95% CI 1.52-5.80) for participants in the 'rimming and frottage' cluster (P=0.001) and 2.28-fold higher (95% CI 0.98-5.31) for participants in the 'toy use and fisting' cluster (P=0.056).

CONCLUSIONS

The prevalence of ESBL-E in MSM is higher compared with the overall Dutch population, likely due to sexual transmission with casual partners. This implies that sexually active MSM should be considered a risk group for ESBL-E carriage.

Prolonged Outbreak of Multidrug-Resistant Shigella sonnei Harboring bla CTX-M-27 in Victoria, Australia

In Australia, cases of shigellosis usually occur in returned travelers from regions of shigellosis endemicity or in men who have sex with men. Resistance to multiple antibiotics has significantly increased in Shigella sonnei isolates and represents a significant public health concern. We investigate an outbreak of multidrug-resistant S. sonnei in Victoria, Australia. We undertook whole-genome sequencing of 54 extended-spectrum-beta-lactamase (ESBL)-producing S. sonnei isolates received at the Microbiological Diagnostic Unit Public Health Laboratory between January 2019 and March 2020.

In Australia, cases of shigellosis usually occur in returned travelers from regions of shigellosis endemicity or in men who have sex with men. Resistance to multiple antibiotics has significantly increased in Shigella sonnei isolates and represents a significant public health concern. We investigate an outbreak of multidrug-resistant S. sonnei in Victoria, Australia. We undertook whole-genome sequencing of 54 extended-spectrum-beta-lactamase (ESBL)-producing S. sonnei isolates received at the Microbiological Diagnostic Unit Public Health Laboratory between January 2019 and March 2020. The population structure and antimicrobial resistance profiles were identified by genomic analyses, with 73 previously characterized Australian S. sonnei isolates providing context. Epidemiological data, including age and sex of the shigellosis cases, were also collected. There was a significant increase in cases of ESBL S. sonnei from July 2019. Most of the ESBL S. sonnei isolates (65%) fell within a single cluster that was predominantly comprised of male cases that were characterized by the presence of the bla_CTX-M-27 gene conferring resistance to extended-spectrum cephalosporins. These isolates were also multidrug resistant, including resistance to azithromycin and co-trimoxazole and reduced susceptibility to ciprofloxacin. Our data uncovered a prolonged clonal outbreak of ESBL S. sonnei infection that was likely first introduced by returned travelers and has subsequently been circulating locally in Australia. The emergence of a local outbreak of ESBL S. sonnei with a multidrug-resistant profile, including reduced susceptibility to ciprofloxacin, represents a significant public health threat.

A Multifactorial Approach for Surveillance of Shigella spp. and Entero-Invasive Escherichia coli Is Important for Detecting (Inter)national Clusters

Shigella spp. and entero-invasive Escherichia coli (EIEC) can cause mild diarrhea to dysentery. In Netherlands, although shigellosis is a notifiable disease, there is no laboratory surveillance for Shigella spp. and EIEC in place. Consequently, the population structure for circulating Shigella spp. and EIEC isolates is not known. This study describes the phenotypic and serological characteristics, the phenotypic and genetic antimicrobial resistance (AMR) profiles, the virulence gene profiles, the classic multi-locus sequence types (MLST) and core genome (cg)MLST types, and the epidemiology of 414 Shigella spp. and EIEC isolates collected during a cross-sectional study in Netherlands in 2016 and 2017. S. sonnei (56%), S. flexneri (25%), and EIEC (15%) were detected predominantly in Netherlands, of which the EIEC isolates were most diverse according to their phenotypical profile, O-types, MLST types, and cgMLST clades. Virulence gene profiling showed that none of the isolates harbored Shiga toxin genes. Most S. flexneri and EIEC isolates possessed nearly all virulence genes examined, while these genes were only detected in approximately half of the S. sonnei isolates, probably due to loss of the large invasion plasmid upon subculturing. Phenotypical resistance correlated well with the resistant genotype, except for the genes involved in resistance to aminoglycosides. A substantial part of the characterized isolates was resistant to antimicrobials advised for treatment, i.e., 73% was phenotypically resistant to co-trimoxazole and 19% to ciprofloxacin. AMR was particularly observed in isolates from male patients who had sex with men (MSM) or from patients that had traveled to Asia. Furthermore, isolates related to international clusters were also circulating in Netherlands. Travel-related isolates formed clusters with isolates from patients without travel history, indicating their emergence into the Dutch population. In conclusion, laboratory surveillance using whole genome sequencing as high-resolution typing technique and for genetic characterization of isolates complements the current epidemiological surveillance, as the latter is not sufficient to detect all (inter)national clusters, emphasizing the importance of multifactorial public health approaches.

Rapid Increase of CTX-M-Producing Shigella sonnei Isolates in Switzerland Due to Spread of Common Plasmids and International Clones

The Swiss Centre for Antibiotic Resistance (ANRESIS) has recently noted an increase of extended-spectrum cephalosporin-resistant (ESC-R) Shigella sonnei isolates nationwide (3.8% in 2016 versus 37.5% in 2019). To understand this phenomenon, we analyzed 25 representative isolates (of which 14 were ESC-R) collected in Switzerland during 2016 to 2019. Whole-genome sequencing was achieved using both the Illumina and the Nanopore platforms. Both ESC-R and extended-spectrum cephalosporin-susceptible isolates belonged to sequence type 152 (ST152). The ESC-R isolates carried bla _CTX-M-3 in IncI1-pST57 (n = 5), bla _CTX-M-15 in IncFII (F2:A-:B-) (n = 5), bla _CTX-M-15 in IncI1-pST16, and bla _CTX-M-27, bla _CTX-M-55, or bla _CTX-M-134 in other IncFII plasmids (n = 1 each). Plasmids having the same bla and Inc group exhibited high degrees of genetic identity to each other but also to plasmids previously reported in other Enterobacterales Core-genome analysis showed that there were 4 main clusters, each of which included strains that differed by <58 single nucleotide variants (SNVs) and that consisted of both bla _CTX-M-positive and bla _CTX-M-negative isolates. Moreover, most isolates belonging to the same cluster shared an identical core-genome sequence type (cgST). For instance, cluster 1 included 4 isolates of cgST113036, of which only 3 harbored the IncI1-pST57 bla _CTX-M-3-positive plasmid. The 25 S. sonnei isolates were also subjected to phylogenetic comparison with deposited international strains. As a result, matching isolates (isolates that had the same cgST and that differed by <8 SNVs) have been reported in the United Kingdom, the United States, France, and the Netherlands. Overall, our results suggest that some common S. sonnei clusters can spread between continents and can be imported into other nations after international trips. Such clusters include, in part, isolates that do not possess bla _ESBL-harboring plasmids, indicating their tendency to acquire them from other Enterobacterales.

Shigella sonnei: virulence and antibiotic resistance

Shigella sonnei is the emerging pathogen globally, as it is the second common infectious species of shigellosis (bloody diarrhoea) in low- and middle-income countries (LMICs) and the leading one in developed world. The multifactorial processes and novel mechanisms have been identified in S. sonnei, that are collectively playing apart a substantial role in increasing its prevalence, while replacing the S. flexneri and other Gram-negative gut pathogens niche occupancy. Recently, studies suggest that due to improvement in sanitation S. sonnei has reduced cross-immunization from Plesiomonas shigelliodes (having same O-antigen as S. sonnei) and also found to outcompete the two major species of Enterobacteriaceae family (Shigella flexneri and Escherichia coli), due to encoding of type VI secretion system (T6SS). This review aimed to highlight S. sonnei as an emerging pathogen in the light of recent research with pondering aspects on its epidemiology, transmission, and pathogenic mechanisms. Additionally, this paper aimed to review S. sonnei disease pattern and related complications, symptoms, and laboratory diagnostic techniques. Furthermore, the available treatment reigns and antibiotic-resistance patterns of S. sonnei are also discussed, as the ciprofloxacin and fluoroquinolone-resistant S. sonnei has already intensified the global spread and burden of antimicrobial resistance. In last, prevention and controlling strategies are briefed to limit and tackle S. sonnei and possible future areas are also explored that needed more research to unravel the hidden mysteries surrounding S. sonnei.

Co-circulation of Multidrug-resistant Shigella Among Men Who Have Sex With Men in Australia

BACKGROUND

In urban Australia, the burden of shigellosis is either in returning travelers from shigellosis-endemic regions or in men who have sex with men (MSM). Here, we combine genomic data with comprehensive epidemiological data on sexual exposure and travel to describe the spread of multidrug-resistant Shigella lineages.

METHODS

A population-level study of all cultured Shigella isolates in the state of Victoria, Australia, was undertaken from 1 January 2016 through 31 March 2018. Antimicrobial susceptibility testing, whole-genome sequencing, and bioinformatic analyses of 545 Shigella isolates were performed at the Microbiological Diagnostic Unit Public Health Laboratory. Risk factor data on travel and sexual exposure were collected through enhanced surveillance forms or by interviews.

RESULTS

Rates of antimicrobial resistance were high, with 17.6% (95/541) and 50.6% (274/541) resistance to ciprofloxacin and azithromycin, respectively. There were strong associations between antimicrobial resistance, phylogeny, and epidemiology. Specifically, 2 major MSM-associated lineages were identified: a Shigellasonnei lineage (n = 159) and a Shigella flexneri 2a lineage (n = 105). Of concern, 147/159 (92.4%) of isolates within the S. sonnei MSM-associated lineage harbored mutations associated with reduced susceptibility to recommended oral antimicrobials: namely, azithromycin, trimethoprim-sulfamethoxazole, and ciprofloxacin. Long-read sequencing demonstrated global dissemination of multidrug-resistant plasmids across Shigella species and lineages, but predominantly associated with MSM isolates.

CONCLUSIONS

Our contemporary data highlight the ongoing public health threat posed by resistant Shigella, both in Australia and globally. Urgent multidisciplinary public health measures are required to interrupt transmission and prevent infection.

Emergence of multidrug-resistant Shigella species harboring extended-spectrum beta-lactamase genes in pediatric patients with diarrhea from southwest of Iran

Owing to the scarce evidence about the multidrug-resistant (MDR) beta-lactamase-producing Shigella isolates in Iran, this study aimed to evaluate the occurrence of extended-spectrum beta-lactamases (ESBL) and AmpC β-lactamases in Shigella species collected in the southwest of Iran. This study was conducted on Shigella species isolated from stool samples of pediatric patients aged less than 15 years suffering from diarrhea. These isolates were identified by bacteriology tests, serotyping, and polymerase chain reaction (PCR). The antibiotic resistance was determined by disc diffusion. The production of ESBLs and AmpC was investigated by phenotypic confirmatory tests and PCR. In total, 79 Shigella isolates, including 46.8% (n = 37) of S. flexneri and 53.2% (n = 42) of S. sonnei, were isolated, respectively. The most effective antibiotic was imipenem with 93.7% of susceptibility followed by ampicillin (29.1%), and cotrimoxazole (30.4%).The resistance rates of ceftriaxone, ceftazidime, and cefotaxime were 41.8%, 34.2%, and 41.8%, respectively. Also, a total of 57 (72.2%) isolates showed MDR profiles. The phenotypic tests showed that 43.0% (34/79) of isolates can produce ESBLs, and no one was positive for ApmC. The frequency of bla_TEM and bla_CTX-M were 30.4% and 32.9%, respectively, while the bla_PER, bla_SHV, and AmpC genes were not detected. The ESBL-producing isolates had a significant (p-value ˂ 0.05) resistance rate against ceftriaxone, ceftazidime, cefotaxime, cefepime, erythromycin, and amikacin. The significant prevalence of MDR Shigella isolates harboring ESBL genes highlights the need for effective surveillance measures to prevent the more spread of drug resistance among species.

Shigellosis Among Gay and Bisexual Men: A Qualitative Assessment to Examine Knowledge, Attitudes, and Practices

BACKGROUND

Shigellosis is a highly contagious enteric bacterial disease transmitted through the fecal-oral route. It is primarily transmitted through person-to-person contact and via contaminated food and water. Outbreaks of shigellosis among men who have sex with men (MSM) attributed to sexual person-to-person contact have been reported. These outbreaks are of concern because they are often caused by multidrug-resistant strains of Shigella. Little is known about shigellosis-related knowledge, attitudes, and practices among gay, bisexual, and other MSM.

METHODS

Six focus groups were conducted among self-identified gay or bisexual men in Atlanta, GA, in Fall 2017. Participants were asked about shigellosis-related knowledge, attitudes, and practices. Focus groups were audio recorded, and the transcribed audio was analyzed using inductive and deductive thematic coding.

RESULTS

Among the 24 focus group participants, most perceived that diarrheal illness was caused by contaminated food. Knowledge of shigellosis and Shigella was low, with most never having heard of the disease or bacteria. Participants did not perceive shigellosis to be a serious health concern, especially when compared with HIV; however, they did perceive gay and bisexual men to be at risk of Shigella infection. Participants reported mixed intentions to change sexual behaviors to prevent shigellosis or talk with sexual partners about diarrhea.

CONCLUSIONS

Health communication and education efforts could be used to increase knowledge about shigellosis and shift perceptions about the severity of shigellosis among gay, bisexual, and other MSM. Additional work is needed to identify effective ways to promote shigellosis-related prevention behaviors among gay, bisexual, and other MSM.

Persistent Transmission of Shigellosis in England Is Associated with a Recently Emerged Multidrug-Resistant Strain of Shigella sonnei

Whole-genome sequencing has enhanced surveillance and facilitated detailed monitoring of the transmission of Shigella species in England. We undertook an epidemiological and phylogenetic analysis of isolates from all cases of shigellosis referred to Public Health England between 2015 and 2018 to explore recent strain characteristics and the transmission dynamics of Shigella species. Of the 4,950 confirmed cases of shigellosis identified during this period, the highest proportion of isolates was Shigella sonnei (54.4%), followed by S. flexneri (39.2%), S. boydii (4.1%), and S. dysenteriae (2.2%). Most cases were adults (82.9%) and male (59.5%), and 34.9% cases reported recent travel outside the United Kingdom. Throughout the study period, diagnoses of S. flexneri and S. sonnei infections were most common in men with no history of recent travel abroad. The species prevalence was not static, with cases of S. flexneri infection in men decreasing between 2015 and 2016 and the number of cases of S. sonnei infection increasing from 2017. Phylogenetic analysis showed this recent increase in S. sonnei infections was attributed to a novel clade that emerged from a Central Asia sublineage exhibiting resistance to ciprofloxacin and azithromycin. Despite changes in species prevalence, diagnoses of Shigella infections in England are persistently most common in adult males without a reported travel history, consistent with sexual transmission among men who have sex with men. The trend toward increasing rates of ciprofloxacin resistance in S. sonnei, in addition to plasmid-mediated azithromycin resistance, is of significant public health concern with respect to the transmission of multidrug-resistant gastrointestinal pathogens and the risk of treatment failures.

Shigellosis in adults: A retrospective study of clinical and epidemiological features in East London

Shigella is a leading cause of gastroenteritis worldwide; however, data on clinical outcomes amongst adults are lacking. All adult cases (>16 years) of Shigella gastroenteritis diagnosed between January 2014 to December 2017 at an East London NHS Trust in the United Kingdom were included. Demographic, clinical, microbiological and whole genome sequencing (WGS) data were retrospectively collected. Shigella spp isolates from 169 cases were identified: S. flexneri 90 (53.3%), S. sonnei 75 (44.9%) and S. boydii 4 (2.0%). The median age was 34 years (IQR 29–45), and 127 (75.1%) were male. S. flexneri cases were more likely to attend accident and emergency (46.7% vs. 25.3%, p = 0.005), be admitted to hospital (26.7% vs. 10.7%, p = 0.01), and receive antibiotics (51.1% vs. 28.0%, p = 0.003) compared to S. sonnei cases. Thirty-two (18.9%) patients were admitted to hospital for a median of five days (IQR 3–8). Where recorded 42/84 (50.0%) reported recent travel. Seventeen (10.1%) patients experienced complications. There were no deaths within one year of diagnosis. Seventy-nine isolates were characterised by WGS. Fifty-seven (72.2%) belonged to known national clusters; 44 (55.7%) involving adult males and 11 (13.9%) travel-associated clusters. We demonstrate the development of severe complications of shigellosis among adults and highlight the changing epidemiology and antibiotic resistance patterns.

Azithromycin non-susceptible Shigella circulating in Israel, 2014-2016

Shigella species remains a major diarrhoeagenic agent, affecting mostly children, with global high incidence and high mortality rate specially in developing areas. Although azithromycin is recommended for treatment of shigellosis, there are currently no CLSI susceptibility breakpoints, accordingly no routine antimicrobial susceptibility test is performed in the clinical laboratory. The purpose of this study was to estimate the prevalence, resistance profile and molecular epidemiology of azithromycin non-susceptible Shigella strains in Israel during a three year period. Shigella isolates (n = 1,170) referred to the National Reference Center during 2014-2016, were included in this study. Serotyping was performed by slide agglutination. Resistance genes, mph(A) and erm(B), were identified by PCR and the phenotype profile was determined by broth microdilution (BMD). Genetic relatedness was assessed by wgMLST. Decreased susceptibility to azithromycin (DSA) phenotype and genotype were detected in various Shigella species and serotypes related to diverse genetic backgrounds and antimicrobial profiles: 6% (26/423) of Shigella flexneri and 2% (16/747) of Shigella sonnei displayed DSA (MIC16 mg/L). Correlation of this phenotype with the presence of mph(A) and erm(B) genes was confirmed. All DSA-strains displayed resistance to ≥3 different antimicrobial classes. Among DSA-strains, 14% were resistant to quinolones and 5% displayed resistance to ceftriaxone. Most of these strains (32/42) were isolated from children in the southern and central regions of Israel. Clonality and significant relatedness was confirmed by PFGE and wgMLST. The presence of macrolide resistance genes among the different species and lineages reflects the transmissible nature of these genes. The emergence of DSA-Shigella reinforces the necessity to establish clinical breakpoints that would warrant routine testing, reporting and surveillance for this drug of choice.

Recent epidemiology of sexually transmissible enteric infections in men who have sex with men

PURPOSE OF REVIEW

Sexual transmission of enteric pathogens in men who have sex with men (MSM) has been described since the 1970s. Recently, an increasing number of enteric infection outbreaks have been reported in MSM. This article summarizes recent outbreaks and discusses the key issues for prevention and control.

RECENT FINDINGS

Sexually transmissible enteric infections (STEIs) can spread rapidly and internationally within highly connected MSM populations and are often associated with antimicrobial resistance (AMR). The infections often cluster in high-risk groups of HIV-positive MSM who are more likely to engage in diverse sexual practices and chemsex, and to have multiple other sexually transmitted infections (STIs).

SUMMARY

The roles of asymptomatic and/or persistent infection and other contextual factors in STEI transmission are not well described. STEI-associated AMR is increasing and has potential to spread rapidly in MSM, warranting further public health attention. A better understanding of the factors associated with sexual transmission will enable the development of more effective control measures. A holistic approach that promotes health and wellbeing as well as infection prevention and management is needed.

A Brief History of Shigella

The history of Shigella, the causative agent of bacillary dysentery, is a long and fascinating one. This brief historical account starts with descriptions of the disease and its impact on human health from ancient time to the present. Our story of the bacterium starts just before the identification of the dysentery bacillus by Kiyoshi Shiga in 1898 and follows the scientific discoveries and principal scientists who contributed to the elucidation of Shigella pathogenesis in the first 100 years. Over the past century, Shigella has proved to be an outstanding model of an invasive bacterial pathogen and has served as a paradigm for the study of other bacterial pathogens. In addition to invasion of epithelial cells, some of those shared virulence traits include toxin production, multiple-antibiotic resistance, virulence genes encoded on plasmids and bacteriophages, global regulation of virulence genes, pathogenicity islands, intracellular motility, remodeling of host cytoskeleton, inflammation/polymorphonuclear leukocyte signaling, apoptosis induction/inhibition, and "black holes" and antivirulence genes. While there is still much to learn from studying Shigella pathogenesis, what we have learned so far has also contributed greatly to our broader understanding of bacterial pathogenesis.

Use of gender distribution in routine surveillance data to detect potential transmission of gastrointestinal infections among men who have sex with men in England

Detecting gastrointestinal (GI) infection transmission among men who have sex with men (MSM) in England is complicated by a lack of routine sexual behavioural data. We investigated whether gender distributions might generate signals for increased transmission of GI pathogens among MSM. We examined the percentage male of laboratory-confirmed patient-episodes for patients with no known travel history for 10 GI infections of public health interest in England between 2003 and 2013, stratified by age and region. An adult male excess was observed for Shigella spp. (annual maximum 71% male); most pronounced for those aged 25-49 years and living in London, Brighton and Manchester. An adult male excess was observed every year for Entamoeba histolytica (range 59.8-76.1% male), Giardia (53.1-57.6%) and Campylobacter (52.1-53.5%) and for a minority of years for hepatitis A (max. 69.8%) and typhoidal salmonella (max. 65.7%). This approach generated a signal for excess male episodes for six GI pathogens, including a characterised outbreak of Shigella among MSM. Stratified analyses by geography and age group were consistent with MSM transmission for Shigella. Optimisation and routine application of this technique by public health authorities elsewhere might help identify potential GI infection outbreaks due to sexual transmission among MSM, for further investigation.

Comparison of phenotypic and WGS-derived antimicrobial resistance profiles of Shigella sonnei isolated from cases of diarrhoeal disease in England and Wales, 2015

Objectives

Phenotypic and genotypic methods for the detection of antimicrobial resistance (AMR) in Shigella sonnei in England and Wales were compared and evaluated.

Methods

WGS data from 341 isolates of S. sonnei isolated between June 2015 and January 2016 were mapped to genes known to be associated with phenotypic AMR. Antimicrobial susceptibility testing was performed on all viable isolates (n = 335).

Results

Fifteen of 335 isolates had a discrepancy between phenotypic and genotypic testing for 1 of the 10 antimicrobial classes tested, equating to 15 (0.45%) discordant results out of a possible 3350 isolate/antimicrobial combinations. All 15 mismatched results were genotypically resistant but phenotypically susceptible. Eleven of the 15 discrepancies were observed in streptomycin resistance profiles. The most common resistance profile was trimethoprim, sulphonamides, tetracyclines and streptomycin, occurring in 97 (28.4%) isolates. Resistances to ciprofloxacin and the third-generation cephalosporins, not detected in England and Wales prior to 2002, were identified in 18.2% and 12% of isolates, respectively. Three hundred and four (89.1%) isolates were MDR. There was no significant association between any of the AMR determinants tested and recent foreign travel in male or female cases. The number of isolates of S. sonnei harbouring blaTEM-1 and ermB/mphA was significantly higher in men who reported no recent travel outside the UK.

Conclusions

The use of WGS for routine public health surveillance is a reliable method for rapid detection of emerging AMR in isolates of S. sonnei.

Shigellosis

Shigellosis is a clinical syndrome caused by invasion of the epithelium lining the terminal ileum, colon, and rectum by Shigella species. Although infections occur globally, and in people of all ages, endemic infections among children aged 1-4 years living in low-income and middle-income settings constitute most of the disease burden. The versatile manifestations of these highly contagious organisms range from acute watery diarrhoea to fulminant dysentery characterised by frequent scant bloody stools with fever, prostration, and abdominal cramps. A broad array of uncommon, but often severe, intestinal and extraintestinal complications can occur. Despite marked reductions in mortality during the past three decades, there are roughly 164 000 annual deaths attributable to shigellosis. Intercontinental dissemination of multiresistant shigella strains, facilitated by travellers and men who have sex with men, has prompted new recommendations for antibiotic therapy. Awareness of disease burden and the emerging threats posed by shigella have accelerated interest in development of shigella vaccines, many of which are being tested in clinical trials.

An adult case with shigellosis-associated encephalopathy

A 45-year-old man was presented at the emergency department with altered neurological status and a 1-day history of diarrhoea and fever. The patient’s sexual history revealed multiple male partners. As bacterial meningitis or viral encephalitis was suspected, treatment was started accordingly. Cerebrospinal fluid investigations only showed a slight increase of leucocytes, and microbiological studies remained negative. Stool culture revealed Shigella flexneri, after which Shigella-associated encephalopathy was suspected. The patient recovered quickly with antibiotic treatment. The incidence of Shigella infections in the Western world is rising due to sexual transmission among men who have sex with men. Shigella-induced encephalopathy is a notorious complication among children with a severe form known as the Ekiri syndrome, though rarely seen in adults. This is the second report of encephalopathy in an adult with S. flexneri enteric infection.

Re-emerging and newly recognized sexually transmitted infections: Can prior experiences shed light on future identification and control?

How do we spot the next sexually transmitted infection? Kyle Bernstein and colleagues look for lessons from past discovery.

Whole-Genome Sequencing for National Surveillance of Shigella flexneri

National surveillance of Shigella flexneri ensures the rapid detection of outbreaks to facilitate public health investigation and intervention strategies. In this study, we used whole-genome sequencing (WGS) to type S. flexneri in order to detect linked cases and support epidemiological investigations. We prospectively analyzed 330 isolates of S. flexneri received at the Gastrointestinal Bacteria Reference Unit at Public Health England between August 2015 and January 2016. Traditional phenotypic and WGS sub-typing methods were compared. PCR was carried out on isolates exhibiting phenotypic/genotypic discrepancies with respect to serotype. Phylogenetic relationships between isolates were analyzed by WGS using single nucleotide polymorphism (SNP) typing to facilitate cluster detection. For 306/330 (93%) isolates there was concordance between serotype derived from the genome and phenotypic serology. Discrepant results between the phenotypic and genotypic tests were attributed to novel O-antigen synthesis/modification gene combinations or indels identified in O-antigen synthesis/modification genes rendering them dysfunctional. SNP typing identified 36 clusters of two isolates or more. WGS provided microbiological evidence of epidemiologically linked clusters and detected novel O-antigen synthesis/modification gene combinations associated with two outbreaks. WGS provided reliable and robust data for monitoring trends in the incidence of different serotypes over time. SNP typing can be used to facilitate outbreak investigations in real-time thereby informing surveillance strategies and providing the opportunities for implementing timely public health interventions.

Prevalence and characteristics of gastrointestinal infections in men who have sex with men diagnosed with rectal chlamydia infection in the UK: an 'unlinked anonymous' cross-sectional study

INTRODUCTION

Gastrointestinal infections (GII) can cause serious ill health and morbidity. Although primarily transmitted through faecal contamination of food or water, transmission through sexual activity is well described, especially among men who have sex with men (MSM).

METHODS

We investigated the prevalence of GIIs among a convenience sample of MSM who were consecutively diagnosed with rectal Chlamydia trachomatis (CT) at 12 UK genitourinary medicine clinics during 10 weeks in 2012. Residual rectal swabs were coded, anonymised and tested for Shigella, Campylobacter, Salmonella, shiga toxin-producing Escherichia coli and enteroaggregative E. coli (EAEC) using a real-time PCR. Results were linked to respective coded and anonymised clinical and demographic data. Associations were investigated using Fisher's exact tests.

RESULTS

Of 444 specimens tested, overall GII prevalence was 8.6% (95% CI 6.3% to 11.6%): 1.8% (0.9% to 3.6%) tested positive for Shigella, 1.8% (0.9% to 3.6%) for Campylobacter and 5.2% (3.5% to 7.7%) for EAEC. No specimens tested positive for Salmonella or other diarrhoeagenic E. coli pathotypes. Among those with any GII, 14/30 were asymptomatic (2/7 with Shigella, 3/6 with Campylobacter and 9/17 with EAEC). Shigella prevalence was higher in MSM who were HIV-positive (4.7% (2.1% to 10.2%) vs 0.5%(0.1% to 3.2%) in HIV-negative MSM; p=0.01).

CONCLUSIONS

In this small feasibility study, MSM with rectal CT appeared to be at appreciable risk of GII. Asymptomatic carriage may play a role in sexual transmission of GII.