Shigellosis in Subjects with Traveler's Diarrhea Versus Domestically Acquired Diarrhea: Implications for Antimicrobial Therapy and Human Immunodeficiency Virus Surveillance

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.

Bacterial travellers' diarrhoea: A narrative review of literature published over the past 10 years

Travellers' diarrhoea (TD) is the most frequent illness experienced by international travellers to lower-income countries with bacterial agents considered to account for 80-90% of cases. In this review, we summarise evidence published on bacterial TD over the past 10 years, focusing on the epidemiology and aetiology of TD. Diarrhoeagenic Escherichia coli (DEC) continue to be the most commonly implicated bacteria in TD, although Enteropathogenic E. coli (EPEC) and Enteroaggregative E. coli (EAEC) now appear to be predominant where Enterotoxigenic E. coli (ETEC) was previously considered most prevalent globally. Where fluroquinolone resistance had primarily been documented for Campylobacter in Southeast Asia, widespread resistance has been observed in most regions of the world for multiple enteropathogens, including Shigella, Salmonella, ETEC and EAEC. Implementation of novel molecular methods for pathogen detection has led to identification of bacterial pathogens, including Clostridium difficile (with and without the use of prior antibiotics), Arcobacter species and Bacteroides fragilis, as aetiological agents in TD. The widespread resistance to first-line antibiotics in multiple bacterial enteropathogens warrants continued surveillance and re-evaluation of current treatment practices. Further investigations are required to determine the prevalence and geographical distribution of bacterial enteropathogens that have been more recently implicated in TD.

Evaluation of the Anti-Shigellosis Activity of Dietary Isothiocyanates in Galleria mellonella Larvae

Cruciferous vegetables, widely present in daily diets, are a rich source of organosulfur compounds with proven health benefits, especially chemopreventive or antioxidative effects. Isothiocyanate derivatives (ITCs) exhibit a broad spectrum of biological and pharmacological activity and recently, their antibacterial properties have been of particular importance. Here, we have focused on the anti-shigellosis activity of sulforaphane (SFN) and phenethyl ITC (PEITC). The genus Shigella causes gastroenteritis in humans, which constitutes a threat to public health. Production of a potent Stx toxin by S. dysenteriae type 1 results not only in more severe symptoms but also in serious sequela, including the hemolytic uremic syndrome. Here, we present evidence that two aliphatic and aromatic ITCs derivatives, SFN and PEITC, have an effective antibacterial potency against S. dysenteriae, also negatively regulating the stx gene expression. The molecular mechanism of this effect involves induction of the global stress-induced stringent response. ITCs also inhibit bacterial virulence against the Vero and HeLa cells. We present evidence for the therapeutic effect of sulforaphane and phenethyl ITC against a S. dysenteriae infection in the Galleria mellonella larvae model. Thus, our results indicate that isothiocyanates can be effectively used to combat dangerous bacterial infections.

Effects of El Niño/La Niña on the Number of Imported Shigellosis Cases in the Republic of Korea, 2004-2017

Shigellosis is a major diarrheal disease in low- and middle-income countries. Although the incidence of such diseases in South and Southeast Asia has been associated with climate fluctuations linked to the El Niño-Southern Oscillation (ENSO), the impact of ENSO on shigellosis infections remains unknown. Data reported to being infected with shigellosis while traveling abroad from 2004 to 2017 were obtained from the Korea Centers for Disease Control and Prevention. We investigated the relationship between the Oceanic Niño Index (ONI) and Indian Ocean Dipole Mode Index and the relative risk of shigellosis in outbound travelers using distributed lag linear and non-linear models. From 2004 to 2017, 87.1% of imported shigellosis was infected in South and Southeast Asian countries. The relative risk of imported shigellosis infection in outbound travelers increased as the ONI decreased. In the association with the five-month cumulative ONI, the relative risk of infection continuously increased as the La Niña index gained strength. Climate fluctuations associated with the La Niña phenomenon in South and Southeast Asian countries can lead to issues in sanitation and water safety. Our findings suggest that the decreasing trend in the ONI is associated with an increased incidence of shigellosis in these countries.

Feasibility of containing shigellosis in Hubei Province, China: a modelling study

Background

The transmission features and the feasibility of containing shigellosis remain unclear among a population-based study in China.

Methods

A population–based Susceptible – Exposed – Infectious / Asymptomatic – Recovered (SEIAR) model was built including decreasing the infectious period (DIP) or isolation of shigellosis cases. We analyzed the distribution of the reported shigellosis cases in Hubei Province, China from January 2005 to December 2017, and divided the time series into several stages according to the heterogeneity of reported incidence during the period. In each stage, an epidemic season was selected for the modelling and assessing the effectiveness of DIP and case isolation.

Results

A total of 130,770 shigellosis cases were reported in Hubei Province. The median of R_eff was 1.13 (range: 0.86–1.21), 1.10 (range: 0.91–1.13), 1.09 (range: 0.92–1.92), and 1.03 (range: 0.94–1.22) in 2005–2006 season, 2010–2011 season, 2013–2014 season, and 2016–2017 season, respectively. The reported incidence decreased significantly (trend χ² = 8260.41, P <  0.001) among four stages. The incidence of shigellosis decreased sharply when DIP implemented in three scenarios (γ = 0.1, 0.1429, 0.3333) and when proportion of case isolation increased.

Conclusions

Year heterogeneity of reported shigellosis incidence exists in Hubei Province. It is feasible to contain the transmission by implementing DIP and case isolation.

Critical Role for the NLRP3 Inflammasome in Mediating IL-1β Production in Shigella sonnei-Infected Macrophages

Shigella is one of the leading bacterial causes of diarrhea worldwide, affecting more than 165 million people annually. Among the serotypes of Shigella, Shigella sonnei is physiologically unique and endemic in human immunodeficiency virus-infected men who have sex with men. The NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome, a protein complex composed of NLRP3, apoptosis-associated speck-like protein, and caspase-1, recognizes, and responds to pathogen infection and diverse sterile host-derived or environmental danger signals to induce IL-1β and IL-18 production. Although the Shigella flexneri-mediated activation of the NLRP3 inflammasome has been reported, the effect of S. sonnei on NLRP3 inflammasome activation remains unclear. We found that S. sonnei induced IL-1β production through NLRP3-dependent pathways in lipopolysaccharide-primed macrophages. A mechanistic study revealed that S. sonnei induced IL-1β production through P₂X₇ receptor-mediated potassium efflux, reactive oxygen species generation, lysosomal acidification, and mitochondrial damage. In addition, the phagocytosis of viable S. sonnei was important for IL-1β production. Furthermore, we demonstrated that NLRP3 negatively regulated phagocytosis and the bactericidal activity of macrophages against S. sonnei. These findings provide mechanistic insight into the activation of the NLRP3 inflammasome by S. sonnei in macrophages.

Health Considerations for HIV-Infected International Travelers

PURPOSE OF THE REVIEW

International travel continues to steadily increase, including leisure travel, travel to one's country of origin to visit friends and relatives, travel for service work, and business travel. Travelers with HIV may have an increased risk for travel-associated infections. The pre-travel medical consultation is an important means of assessing one's risk for travel-related health issues. The aim of this review is to provide an update on key health considerations for the HIV-infected traveler.

RECENT FINDINGS

Like all travelers, the HIV-infected traveler should adhere to behavioral precautions, including safety measures with food and water consumption, safe sexual practices, and arthropod bite avoidance. HIV is a risk factor for venous thromboembolism and patients should be educated regarding this risk. Most pre-travel vaccines are safe and immunogenic in HIV-infected individuals, though live vaccines should be avoided in patients with low CD4 counts. Malaria chemoprophylaxis is strongly recommended in patients with HIV traveling to endemic areas and no significant interactions exist between the commonly used prophylactic anti-malarial agents and anti-retroviral therapy (ART). Travelers with HIV, particularly those who are not on ART or who have low CD4 cell counts, may have increased risk for tuberculosis, malaria, enteric infections, visceral leishmaniasis, American trypanosomiasis, and endemic mycoses such as histoplasmosis, talaromycosis, and coccidioidomycosis. The immune status of the HIV-infected traveler should be assessed prior to travel along with the duration, itinerary, and activities planned during travel in order to carefully consider individual risk for travel-related health issues.

Resistant pathogens as causes of traveller's diarrhea globally and impact(s) on treatment failure and recommendations

BACKGROUND

: Diarrhea is a frequent clinical syndrome affecting international travellers. Bacterial etiologic agents have a long history of emergent antimicrobial resistance against commonly used antibiotics. Current approaches applying first-line antimicrobial therapy are being challenged by increasingly resistant organisms. This review summarizes recent epidemiological and clinical evidence of antibiotic resistance among enteropathogens causing traveller's diarrhea and the subsequent impact on current treatment recommendations.

METHODS

: The PubMed database was systemically searched for articles related to antibiotic susceptibility and diarrheal pathogens.

RESULTS

: Antibiotic resistance related to travellers' diarrhea has increased in recent years. Most notably, fluoroquinolone resistance has expanded from the Campylobacter -associated cases well documented in Southeast Asia in the 1990s to widespread occurrence, as well as increases among other common bacterial enteropathogens including, enterotoxigenic and enteroaggregative Escherichia coli , Shigella and non-typhoidal Salmonella . Multidrug resistance among enteropathogenic Enterobacteriacae and Campylobacter species create further challenges with the selection of empiric therapy. Treatment failures requiring early use of alternative agents, as well as delayed recovery comparable to placebo rates emphasize the impact of antimicrobial resistance on effective treatment.

CONCLUSIONS

: Although there are limitations in the available data, the increasing antibiotic resistance and adverse impact on clinical outcome require continued surveillance and reconsideration of practice guidelines.

Investigation of Efflux-Mediated Tetracycline Resistance in Shigella Isolates Using the Inhibitor and Real Time Polymerase Chain Reaction Method

BACKGROUND

Shigella spp. are gram negative bacteria, which are of global public health importance. The growing of multidrug-resistant Shigella isolates are a major problem around the world.

METHODS

Overall, 50 isolates of Shigella spp. from children diarrheic stools were studied. The isolates were identified and confirmed using biochemical, serological and molecular methods (ipaH, wbgZ and rfc genes). Antimicrobial susceptibility test was done according to the Clinical and Laboratory Standards Institute (CLSI) guidelines against minocycline, tetracycline, doxycycline, ampicillin, streptomycin, trimethoprim-sulfamethoxazole, nalidixic acid, norfloxacin, ciprofloxacin and levofloxacin. Also, the role of efflux pump in defense of Shigella against tetracycline was investigated by Minimum Inhibitory Concentration (MIC) with and without an efflux pump inhibitor. Detection of tetA, tetB, tetC and tetD genes in Shigella was evaluated by conventional Polymerase Chain Reaction (PCR) and real time PCR.

RESULTS

Molecular identification revealed a prevalence of 14% for Shigella flexneri and 86% for Shigella sonnei. Minimum Inhibitory Concentration (MIC) of 90% of resistant isolates was changed in the presence CCCP. Results of conventional PCR exhibited that 66% of isolates were positive for tetA, while according to real time PCR method, 90% of isolates carried tetA. Positive results for tetB were 12% and 18% by conventional and real time PCR methods, respectively. No positive results were detected for tetC and tetD. Also, tetB was detected only in S. flexneri while tetA was detected in both S. flexneri and S. sonnei.

CONCLUSION

It seems that efflux-mediated tetracycline resistance to tetracycline in S. flexneri can be related to tetB, however resistance in S. sonnei can be related to the expression of tetA.

Multi-locus sequence type analysis of Shigellas pp. isolates from Tehran, Iran

BACKGROUND AND OBJECTIVES

Strains of Shigella spp. can cause shigellosis, or bacillary dysentery. that is a public health problem worldwide. The aim of this study was to describe the population structure and genetic relatedness of multidrug resistant S. sonnei and S. flexneri isolated during a one year period from children with diarrhea in Tehran, Iran.

MATERIALS AND METHODS

A total of 70 Shigella spp. were detected during the study period. Twenty MDR isolates of Shigella spp. were randomly selected and used in this study. Bacterial identification was performed by conventional biochemical and serological and confirmed by molecular method. After antimicrobial susceptibility testing, we used Multilocus sequence typing (MLST) for subtyping isolates.

RESULTS

We found 14 Shigella sonnei and 6 Shigella flexneri isolates. Results of MLST showed five sequence types (ST) (145, 152, 241, 245, 1502) and BURST analysis revealed the largest number of single locus variant (SLV) and highest frequency (FREQ) for ST152. ST 152 with nine members was predicted as the founder by BURST. Frequency for ST 1502 and ST 245 was four isolates and the least frequency was seen for ST 241 and 145 with one and two members, respectively. ST 145 and ST 245 were described as singletons in BURST. All isolates with ST145 and ST245 were identified as Shigella flexneri.

CONCLUSION

Annual Multi locus sequence typing of MDR Shigella would help us in better understanding of dominant species and comparing our results with the same studies in other countries especially our neighbor countries in source tracking purposes.