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Abstract We examined the stools of 23 patients in Kolkata, who were diagnosed as cholera patients because Vibrio cholerae O1 was detected from their stools by culturing methods, and further explored by metagenomic sequencing analysis. Subsequently, the presence of the gene encoding A subunit of cholera toxin (ctxA) and the cholera toxin (CT) level in these stool samples were examined. ctxA was examined by both metagenomic sequencing analysis and polymerase chain reaction. In these examinations, two samples did not show positive in any of these tests. The metagenomic analysis showed that the genes for Streptococcus pneumoniae and Salmonella enterica were present in the stools of these two patients, respectively. Therefore, these two patients were not considered to have diarrhea due to V. cholerae infection. From these results, we predicted that some Kolkata residents harbor a small number of V. cholerae in their intestines as a form of subclinical infection with V. cholerae. Next, we analyzed the stool samples of 22 diarrhea patients from which V. cholerae was not isolated. The results showed that 3 of the patients seemed to have subclinical infection of V. cholerae based on the amount of the genes. These results indicated that subclinical infections with V. cholerae O1 occur in Kolkata.

The O139 Vibrio cholerae serogroup emerged in the 1990s and spread rapidly but did not become globally dominant. Here, the authors describe the genomic epidemiology of this strain and identify changes in virulence and antimicrobial resistance characteristics that they hypothesise may have contributed to its decline.

Antimicrobial resistance (AMR) in bacteria is an important global health problem affecting humans, animals, and the environment. AMR is considered as one of the major components in the “global one health”. Misuse/overuse of antibiotics in any one of the segments can impact the integrity of the others. In the presence of antibiotic selective pressure, bacteria tend to develop several defense mechanisms, which include structural changes of the bacterial outer membrane, enzymatic processes, gene upregulation, mutations, adaptive resistance, and biofilm formation. Several components of mobile genetic elements (MGEs) play an important role in the dissemination of AMR. Each one of these components has a specific function that lasts long, irrespective of any antibiotic pressure. Integrative and conjugative elements (ICEs), insertion sequence elements (ISs), and transposons carry the antimicrobial resistance genes (ARGs) on different genetic backbones. Successful transfer of ARGs depends on the class of plasmids, regulons, ISs proximity, and type of recombination systems. Additionally, phage-bacterial networks play a major role in the transmission of ARGs, especially in bacteria from the environment and foods of animal origin. Several other functional attributes of bacteria also get successfully modified to acquire ARGs. These include efflux pumps, toxin-antitoxin systems, regulatory small RNAs, guanosine pentaphosphate signaling, quorum sensing, two-component system, and clustered regularly interspaced short palindromic repeats (CRISPR) systems. The metabolic and virulence state of bacteria is also associated with a range of genetic and phenotypic resistance mechanisms. In spite of the availability of a considerable information on AMR, the network associations between selection pressures and several of the components mentioned above are poorly understood. Understanding how a pathogen resists and regulates the ARGs in response to antimicrobials can help in controlling the development of resistance. Here, we provide an overview of the importance of genetic network and regulation of AMR in bacterial pathogens.

Objectives This study aimed to identify virulent and antimicrobial resistant genes in fecal E. coli in Mbouda, Cameroon. Methods A total of 599 fecal samples were collected from patients with enteric infections who were ≥ 20 years old. E. coli was isolated on the MacConkey agar and virulent genes were detected by multiplex/simplex PCR. Isolates in which ≥ 1 virulent gene was detected were subjected to antibiotic susceptibility testing. The resulting resistant isolates were subjected to PCR, followed by sequencing for resistant genes detection. Results There were 119 enterovirulent E. coli identified, amongst which 47.05% were atypical enteropathogenic E. coli (EPEC), 36.97% enterotoxigenic E. coli, 10.08% Shiga toxin producing E. coli (STEC) and 5.88% were enteroinvasive E. coli (EIEC). The occurrence of the eae gene (47.06%) was higher compared with CVD432 (33.61%), aaic (13.45%), stx2 (10.08%) and stx1 (0.84%). High resistance rates were noted for ampicillin (94.64% EPEC, 91.67% STEC, 59.09% EAEC, and 57.14% EIEC) and sulfamethoxazole-trimethoprim (100% EPEC and 83.33% STEC, 81.82% EAEC and 71.43% EIEC). sul2 (71.43%), tetB (64.71%), tetA (59.94%) and blaTEM (52.10%) were detected. A double mutation (S83L; D87N) was seen in gyrA and a single mutation (S80I) was observed in parC. Conclusion These findings suggested that measures should be taken to reduce the harm of E. coli to public health.

Acinetobacter baumannii (A. baumannii) is a leading cause of nosocomial infections as this pathogen has certain attributes that facilitate the subversion of natural defenses of the human body. A. baumannii acquires antibiotic resistance determinants easily and can thrive on both biotic and abiotic surfaces. Different resistance mechanisms or determinants, both transmissible and non-transmissible, have aided in this victory over antibiotics. In addition, the propensity to form biofilms (communities of organism attached to a surface) allows the organism to persist in hospitals on various medical surfaces (cardiac valves, artificial joints, catheters, endotracheal tubes, and ventilators) and also evade antibiotics simply by shielding the bacteria and increasing its ability to acquire foreign genetic material through lateral gene transfer. The biofilm formation rate in A. baumannii is higher than in other species. Recent research has shown how A. baumannii biofilm-forming capacity exerts its effect on resistance phenotypes, development of resistome, and dissemination of resistance genes within biofilms by conjugation or transformation, thereby making biofilm a hotspot for genetic exchange. Various genes control the formation of A. baumannii biofilms and a beneficial relationship between biofilm formation and “antimicrobial resistance” (AMR) exists in the organism. This review discusses these various attributes of the organism that act independently or synergistically to cause hospital infections. Evolution of AMR in A. baumannii, resistance mechanisms including both transmissible (hydrolyzing enzymes) and non-transmissible (efflux pumps and chromosomal mutations) are presented. Intrinsic factors [biofilm-associated protein, outer membrane protein A, chaperon-usher pilus, iron uptake mechanism, poly-β-(1, 6)-N-acetyl glucosamine, BfmS/BfmR two-component system, PER-1, quorum sensing] involved in biofilm production, extrinsic factors (surface property, growth temperature, growth medium) associated with the process, the impact of biofilms on high antimicrobial tolerance and regulation of the process, gene transfer within the biofilm, are elaborated. The infections associated with colonization of A. baumannii on medical devices are discussed. Each important device-related infection is dealt with and both adult and pediatric studies are separately mentioned. Furthermore, the strategies of preventing A. baumannii biofilms with antibiotic combinations, quorum sensing quenchers, natural products, efflux pump inhibitors, antimicrobial peptides, nanoparticles, and phage therapy are enumerated.

Cholera toxin (CT)-producing Vibrio cholerae O1 and O139 cause acute diarrheal disease and are proven etiological agents of cholera epidemics and pandemics. On the other hand, V. cholerae non-O1/non-O139 are designated as non-agglutinable (NAG) vibrios and are not associated with epidemic cholera. The majority of NAG vibrios do not possess the gene for CT (ctx). In this study, we isolated three NAG strains (strains No. 1, 2, and 3) with ctx from pond water in Kolkata, India, and examined their pathogenic properties. The enterotoxicity of the three NAG strains in vivo was examined using the rabbit ileal intestinal loop test. Strain No. 1 induced the accumulation of fluid in the loop, and the volume of fluid was reduced by simultaneous administration of anti-CT antiserum into the loop. The volume of fluid in the loop caused by strains No. 2 and 3 was small and undetectable, respectively. Then, we cultured these three strains in liquid medium in vitro at two temperatures, 25°C and 37°C, and examined the amount of CT accumulated in the culture supernatant. CT was accumulated in the culture supernatant of strain No.1 when the strain was cultured at 25°C, but that was low when cultured at 37°C. The CT amount accumulated in the culture supernatants of the No. 2 and No. 3 strains was extremely low at both temperature under culture conditions examined. In order to clarify the virulence properties of these strains, genome sequences of the three strains were analyzed. The analysis showed that there was no noticeable difference among three isolates both in the genes for virulence factors and regulatory genes of ctx. However, vibrio seventh pandemic island-II (VSP-II) was retained in strain No. 1, but not in strains No. 2 or 3. Furthermore, it was revealed that the genotype of the B subunit of CT in strain No. 1 was type 1 and those of strains No. 2 and 3 were type 8. Histopathological examination showed the disappearance of villi in intestinal tissue exposed to strain No. 1. In addition, fluid accumulated in the loop due to the action of strain No. 1 had hemolytic activity. This indicated that strain No. 1 may possesses virulence factors to induce severe syndrome when the strain infects humans, and that some strains of NAG vibrio inhabiting pond water in Kolkata have already acquired virulence, which can cause illness in humans. There is a possibility that these virulent NAG vibrios, which have acquired genes encoding factors involved in virulence of V. cholerae O1, may emerge in various parts of the world and cause epidemics in the future.

Enteric fever is a severe systemic infection caused by Salmonella enterica serovar Typhi (ST) and Salmonella enterica serovar Paratyphi A (SPA). Detection of ST and SPA in wastewater can be used as a surveillance strategy to determine burden of infection and identify priority areas for water, sanitation, and hygiene interventions and vaccination campaigns. However, sensitive and specific detection of ST and SPA in environmental samples has been challenging. In this study, we developed and validated two methods for concentrating and detecting ST/SPA from wastewater: the Moore swab trap method for qualitative results, and ultrafiltration (UF) for sensitive quantitative detection, coupled with qPCR. We then applied these methods for ST and SPA wastewater surveillance in Kolkata, India and Dhaka, Bangladesh, two enteric fever endemic areas. The qPCR assays had a limit of detection of 17 equivalent genome copies (EGC) for ST and 25 EGC for SPA with good reproducibility. In seeded trials, the Moore swab method had a limit of detection of approximately 0.05–0.005 cfu/mL for both ST and SPA. In 53 Moore swab samples collected from three Kolkata pumping stations between September 2019 and March 2020, ST was detected in 69.8% and SPA was detected in 20.8%. Analysis of sewage samples seeded with known amount of ST and SPA and concentrated via the UF method, followed by polyethylene glycol precipitation and qPCR detection demonstrated that UF can effectively recover approximately 8, 5, and 3 log10 cfu of seeded ST and SPA in 5, 10, and 20 L of wastewater. Using the UF method in Dhaka, ST was detected in 26.7% (8/30) of 20 L drain samples with a range of 0.11–2.10 log10 EGC per 100 mL and 100% (4/4) of 20 L canal samples with a range of 1.02–2.02 log10 EGC per 100 mL. These results indicate that the Moore swab and UF methods provide sensitive presence/absence and quantitative detection of ST/SPA in wastewater samples.

Cholera is an acute diarrheal disease caused by pathogenic strains of V. cholerae

Phages, such as those infecting Bacteroides spp., have been proven to be reliable indicators of human fecal contamination in microbial source tracking (MST) studies, and the efficacy of these MST markers found to vary geographically. This study reports the application and evaluation of candidate MST methods (phages infecting previously isolated B. fragilis strain GB-124, newly isolated Bacteroides strains (K10, K29, and K33) and recently isolated Kluyvera intermedia strain ASH-08), along with non-source specific somatic coliphages (SOMCPH infecting strain WG-5) and indicator bacteria (Escherichia coli) for identifying fecal contamination pathways in Kolkata, India. Source specificity of the phage-based methods was first tested using 60 known non-human fecal samples from common animals, before being evaluated with 56 known human samples (municipal sewage) collected during both the rainy and dry season. SOMCPH were present in 40-90% of samples from different animal species and in 100% of sewage samples. Phages infecting Bacteroides strain GB-124 were not detected from the majority (95%) of animal samples (except in three porcine samples) and were present in 93 and 71% of the sewage samples in the rainy and dry season (Mean = 1.42 and 1.83 log10PFU/100mL, respectively), though at lower levels than SOMCPH (Mean = 3.27 and 3.02 log10PFU/100mL, respectively). Phages infecting strain ASH-08 were detected in 89 and 96% of the sewage samples in the rainy and dry season, respectively, but were also present in all animal samples tested (except goats). Strains K10, K29, and K30 were not found to be useful MST markers due to low levels of phages and/or co-presence in non-human sources. GB-124 and SOMCPH were subsequently deployed within two low-income neighborhoods to determine the levels and origin of fecal contamination in 110 environmental samples. E. coli, SOMCPH, and phages of GB-124 were detected in 68, 42, and 28% of the samples, respectively. Analyses of 166 wastewater samples from shared community toilets and 21 samples from sewage pumping stations from the same districts showed that SOMCPH were present in 100% and GB-124 phages in 31% of shared toilet samples (Median = 5.59 and

Helicobacter pylori (H. pylori) infection is considered as one of the strongest risk factors for gastric disorders. Infection triggers several host pathways to elicit inflammation, which further proceeds towards gastric complications. The NF-kB pathway plays a central role in the upregulation of the pro-inflammatory cytokines during infection. It also regulates the transcriptional network of several inflammatory cytokine genes. Hence, targeting NF-kB could be an important strategy to reduce pathogenesis. Moreover, treatment of H. pylori needs attention as current therapeutics lack efficacy due to antibiotic resistance, highlighting the need for alternative therapeutic approaches. In this study, we investigated the effects of capsaicin, a known NF-kB inhibitor in reducing inflammation and gastric complications during H. pylori infection. We observed that capsaicin reduced NF-kB activation and upregulation of cytokine genes in an in vivo mice model. Moreover, it affected NF-kB–miRNA interplay to repress inflammation and gastric damages. Capsaicin reduced the expression level of mir21 and mir223 along with the pro-inflammatory cytokines. The repression of miRNA further affected downstream targets such as e-cadherin and Akt. Our data represent the first evidence that treatment with capsaicin inhibits inflammation and induces antimicrobial activity during H. pylori infection. This alternative approach might open a new avenue in treating H. pylori infection, thus reducing gastric problems.

ABSTRACT Vibrio cholerae serogroup O1 is responsible for epidemic and pandemic cholera and remains a global public health threat. This organism has been well established as a resident flora of the aquatic environment that alters its phenotypic and genotypic attributes for better adaptation to the environment. To reveal the diversity of clinical isolates of V. cholerae O1 in the Bay of Bengal, we performed whole-genome sequencing of isolates from Kolkata, India, and Dhaka, Bangladesh, collected between 2009 and 2016. Comparison with global isolates by phylogenetic analysis placed the current isolates in two Asian lineages, with lineages 1 and 2 predominant in Dhaka and Kolkata, respectively. Each lineage possessed different genetic traits in the cholera toxin B subunit gene, Vibrio seventh pandemic island II, integrative and conjugative element, and antibiotic-resistant genes. Thus, although recent global transmission of V. cholerae O1 from South Asia has been attributed only to isolates of lineage 2, another distinct lineage exists in Bengal. IMPORTANCE Cholera continues to be a global concern, as large epidemics have occurred recently in Haiti, Yemen, and countries of sub-Saharan Africa. A single lineage of Vibrio cholerae O1 has been considered to be introduced into these regions from South Asia and to cause the spread of cholera. Using genomic epidemiology, we showed that two distinct lineages exist in Bengal, one of which is linked to the global lineage. The other lineage was found only in Iran, Iraq, and countries in Asia and differed from the global lineage regarding cholera toxin variant and drug resistance profile. Therefore, the potential transmission of this lineage to other regions would likely cause worldwide cholera spread and may result in this lineage replacing the current global lineage.

The human pathogen Vibrio cholerae is the causative agent of severe diarrheal disease known as cholera. Of the more than 200 “O” serogroups of this pathogen, O1 and O139 cause cholera outbreaks and epidemics. The rest of the serogroups, collectively known as non-O1/non-O139 cause sporadic moderate or mild diarrhea and also systemic infections. Pathogenic V. cholerae circulates between nutrient-rich human gut and nutrient-deprived aquatic environment. As an autochthonous bacterium in the environment and as a human pathogen, V. cholerae maintains its survival and proliferation in these two niches. Growth in the gastrointestinal tract involves expression of several genes that provide bacterial resistance against host factors. An intricate regulatory program involving extracellular signaling inputs is also controlling this function. On the other hand, the ability to store carbon as glycogen facilitates bacterial fitness in the aquatic environment. To initiate the infection, V. cholerae must colonize the small intestine after successfully passing through the acid barrier in the stomach and survive in the presence of bile and antimicrobial peptides in the intestinal lumen and mucus, respectively. In V. cholerae, virulence is a multilocus phenomenon with a large functionally associated network. More than 200 proteins have been identified that are functionally linked to the virulence-associated genes of the pathogen. Several of these genes have a role to play in virulence and/or in functions that have importance in the human host or the environment. A total of 524 genes are differentially expressed in classical and El Tor strains, the two biotypes of V. cholerae serogroup O1. Within the host, many immune and biological factors are able to induce genes that are responsible for survival, colonization, and virulence. The innate host immune response to V. cholerae infection includes activation of several immune protein complexes, receptor-mediated signaling pathways, and other bactericidal proteins. This article presents an overview of regulation of important virulence factors in V. cholerae and host response in the context of pathogenesis.

Clostridium perfringens is one of the most important globally recognised gastroenteric pathogen in humans as well as animals. The present study was aimed to know the similarities/divergence among C. perfringens type A isolates of human and animal origin using the pulsed-field gel electrophoresis (PFGE) as a molecular tool. The enterotoxic isolates obtained by screening of human diarrhoeal cases (n = 130), diarrhoeal cases of pig (n = 52) and goat (n = 50), meat samples viz., pork (n = 59) and chevon (n = 57) were characterized by standard cultural and biochemical methods followed by PCR Assays. Accordingly, a total of 11 C. perfringens type A characterized isolates (16S rRNA+, cpa+, cpb2+ and cpe+) recovered from human diarrhoeal cases (n = 3); diarrhoeal cases of pig (n = 2) and goat (n = 2); meat samples viz. pork (n = 2) and chevon (n = 2) were examined employing PFGE. The observed clustering pattern in PFGE analysis showed the relatedness between isolates from diarrhoeal goat and chevon (90–100%); diarrhoeal pig and pork (65–68%); moreover, isolates from human diarrhoeal cases were exhibiting lineage to cases from goat and pig diarrhoea as well pork and chevon by 62–68% relatedness. The outcome of the present study indicates the probable contamination of this pathogen to the human food chain through faeces from suspected food animals viz. goat and pig and their improperly cooked meat. Keywords: Clostridium perfringens type A, cpb2 gene, cpe gene, Gastroenteritis, PFGE

Abstract Background Campylobacter is a well-known bacterial pathogen for triggering acute gastroenteritis in humans both in developed and developing countries. This organism is highly resistant to fluoroquinolones. Macrolides are very much useful for the treatment of campylobacteriosis when clinical therapy is necessary. However, increasing resistance to azithromycin, a potent macrolide has been reported in Campylobacter in recent years. Macrolide resistance in Campylobacter is found mainly due to point mutation in V region of 23S rRNA. Results We have developed a PCR based assay, which can detect the azithromycin resistant and sensitive Campylobacter strains utilizing mutation responsible for the phenotype. This PCR was validated using 359 Campylobacter strains isolated from diarrhoeal patients at Kolkata, India. Antimicrobial resistance through disk diffusion method was also performed on these strains as a gold standard. Studies through sequencing analysis further confirmed the PCR result. Conclusion This study describes a simple and rapid method for detection of mutation conferring macrolide resistance with additional feature of identification of sensitive strains.

The self-transferring integrative and conjugative elements (ICEs) are large genomic segments carrying several bacterial adaptive functions including antimicrobial resistance (AMR). SXT/R391 family is one of the ICEs extensively studied in cholera-causing pathogen Vibrio cholerae. The genetic characteristics of ICE-SXT/R391 in V. cholerae are dynamic and region-specific. These ICEs in V. cholerae are strongly correlated with resistance to several antibiotics such as tetracycline, streptomycin and trimethoprim-sulfamethoxazole. We screened V. cholerae O1 strains isolated from cholera patients in Kolkata, India from 2008 to 2015 for antibiotic susceptibility and the presence of ICEs, and subsequently sequenced their conserved genes. Resistance to tetracycline, streptomycin and trimethoprim-sulfamethoxazole was detected in strains isolated during 2008–2010 and 2014–2015. The genes encoding resistance to tetracycline (tetA), trimethoprim-sulfamethoxazole (dfrA1 and sul2), streptomycin (strAB), and chloramphenicol (floR) were detected in the ICEs of these strains. There was a decrease in overall drug resistance in V. cholerae associated with the ICEs in 2011. DNA sequence analysis also showed that AMR in these strains was conferred mainly by two types of ICEs, i.e., ICETET (comprising tetA, strAB, sul2, and dfrA1) and ICEGEN (floR, strAB, sul2, and dfrA1). Based on the genetic structure, Kolkata strains of V. cholerae O1 had distinct genetic traits different from the ICEs reported in other cholera endemic regions. Transfer of AMR was confirmed by conjugation with sodium azide resistant Escherichia coli J53. In addition to the acquired resistance to streptomycin and trimethoprim-sulfamethoxazole, the conjugally transferred (CT) E. coli J53 with ICE showed higher resistance to chloramphenicol and tetracycline than the donor V. cholerae. Pulsed-field gel electrophoresis (PFGE) based clonal analysis revealed that the V. cholerae strains could be grouped based on their ICEs and AMR patterns. Our findings demonstrate the epidemiological importance of ICEs and their role in the emergence of multidrug resistance (MDR) in El Tor vibrios.

ABSTRACT The azithromycin resistance conferred by phosphotransferase is encoded in the gene mph(A). This gene has been discovered in and reported for many bacterial species. We examined the prevalence of azithromycin resistance in Vibrio fluvialis (AR-VF) isolated during 2014 to 2015 from the hospitalized acute diarrheal patients in Kolkata, India. Most of the V. fluvialis isolates are identified as the sole pathogen (54%). The prevalence of AR-VF was higher in 2015 (19 [68%]) than in 2014 (9 [32%]). Among AR-VF isolates, the azithromycin MICs ranged from 4 to >256 mg/liter. Twenty-eight of the 48 (58%) V. fluvialis isolates harbored the gene mph(A) and phenotypically resistant to azithromycin. All the AR-VF isolates remained susceptible to doxycycline. In addition to azithromycin, other antimicrobial resistance-encoding genes of AR-VF were also characterized. All the AR-VF isolates were positive for class 1 integron, and most of them (17/28) carried the dfrA1 gene cassettes. Only one isolate was positive for the ereA gene, which encodes resistance to erythomycin. The majority of the isolates were resistant to β-lactam antibiotics (blaOXA-1 [96%], blaOXA-7 [93%], and blaTEM-9 [68%]) and aminoglycoside actetyltransferase, conferring resistance to ciprofloxacin-modifying enzyme [aac(6′)Ib-cr] (96%). Analyses by pulsed-field gel electrophoresis (PFGE) showed that the AR-VF isolates belonged to different genetic lineages. This is the first study to report azithromycin resistance and the presence of the mph(A) gene in V. fluvialis isolates. Circulation of AR-VF isolates with high azithromycin MICs is worrisome, since it may limit the treatment options for diarrheal infections. IMPORTANCE The progressive rise in antibiotic resistance among enteric pathogens in developing countries is becoming a big concern. India is one of the largest consumers of antibiotics, and their use is not well regulated. V. fluvialis is increasingly recognized as an emerging diarrheal pathogen of public health importance. Here we report the emergence of azithromycin resistance in V. fluvialis isolates from diarrheal patients in Kolkata, India. Azithromycin has been widely used in the treatment of various infections, both in children and in adults. Resistance to azithromycin is encoded in the gene mph(A). Emerging azithromycin resistance in V. fluvialis is a major public health challenge, and future studies should be focused on identifying ways to prevent the dissemination of this antibiotic resistance gene.

Background and Objectives: Non-typhoidal Salmonellosis, a zoonotic infection associated with acute gastroenteritis is caused by non-typhoidal salmonellae (NTS). The study was carried out to determine the prevalence of NTS serovars and their antimicrobial resistance along with the presence of the virulence gene (invA gene) in poultry samples. Materials and Methods: This is a prospective cross-sectional study carried out at the Enteric Diseases Division, Kasturba Medical College, Manipal, South India from January 2016– December 2017. Poultry samples were collected randomly from two local poultry farms in Udupi district and processed following CDC standard protocol. Results: From the 396 poultry meat samples, intestinal contents and faecal samples collected, 58 NTS serovars were isolated showing a prevalence of 14.64%. Salmonella Infantis, 43.1%, 25/58 was the commonest serovar. Resistance to ciprofloxacin 72.41%, ampicillin 32.8%, gentamicin 17.24%, cotrimoxazole 29.31% and amoxicillin-clavulanic acid 6.9% was observed. The invA gene was detected in 43 NTS isolates (74.13%). Conclusion: Poultry sources are recognized as a significant cause for non-typhoidal salmonellosis. Therefore, hygienic measures should be initiated to reduce the contamination of meat and poultry products with virulent strains of Salmonella that are of public health significance.

Vibrio cholerae causes fatal diarrheal disease cholera in humans due to consumption of contaminated water and food. To instigate the disease, the bacterium must evade the host intestinal innate immune system; penetrate the mucus layer of the small intestine, adhere and multiply on the surface of microvilli and produce toxin(s) through the action of virulence associated genes. V. cholerae O1 that has caused a major cholera outbreak in Haiti contained several unique genetic signatures. These novel traits are used to differentiate them from the canonical El Tor strains. Several studies reported the spread of these Haitian variant strains in different parts of the world including Asia and Africa, but there is a paucity of information on the clinical consequence of these genetic changes. To understand the impact of these changes, we undertook a study involving mice and rabbit models to evaluate the pathogenesis. The colonization ability of Haitian variant strain in comparison to canonical El Tor strain was found to be significantly more in both suckling mice and rabbit model. Adult mice also displayed the same results. Besides that, infection patterns of Haitian variant strains showed a completely different picture. Increased mucosal damaging, colonization, and inflammatory changes were observed through hematoxylin-eosin staining and transmission electron microscopy. Fluid accumulation ability was also significantly higher in rabbit model. Our study indicated that these virulence features of the Haitian variant strain may have some association with the severe clinical outcome of the cholera patients in different parts of the world.

Carbapenems have been used for many years to treat severe nosocomial Enterobacteriaceae infections. The spread of resistance to these drugs among other bacterial families is an emerging problem worldwide, mostly caused by New Delhi metallo-β-lactamase (NDM-1). We screened for the prevalence of NDM-1–expressing enteric pathogens from hospitalized patients with acute diarrhea in Kolkata, India, and identified 27 Vibrio fluvialis–harboring blaNDM-1 (NDM-VF) strains. These isolates were also resistant to all the tested antimicrobial drugs except doxycycline. The large plasmid of V. fluvialis harboring blaNDM-1 could be easily transferred to other enteric pathogens. Genes flanking the blaNDM-1 were found to be identical to the reported sequence from an Escherichia coli isolate. Analyses showed that the V. fluvialis possessing the NDM-VF region belonged to different clones. The pathogenicity of V. fluvialis to humans and its ubiquitous presence in the environment call for constant monitoring of this species for emerging antimicrobial drug resistance.

We identified 281 Vibrio cholerae non-O1, non-O139 strains from patients with diarrhea in Kolkata, India. Cholera-like diarrhea was the major symptom (66.0%); some patients (20.3%) had severe dehydration. These strains lacked the ctxA gene but many had hlyA, rtxA, and rtxC genes. Pulsed-field gel electrophoresis showed no genetic link among strains.

Incidence of epidemic Vibrio cholerae serogroup O139 has declined in cholera endemic countries. However, sporadic cholera caused by V. cholerae O139 with notable genetic changes is still reported from many regions. In the present study, 42 V. cholerae O139 strains isolated from 2001 to 2006 in Delhi, India, were retrospectively analyzed to understand their phenotype and molecular characteristics. The majority of isolates were resistant to ampicillin, furazolidone and nalidixic acid. Though the integrative conjugative element was detected in all the O139 isolates, the 2004-2006 isolates remained susceptible to co-trimoxazole, chloramphenicol, and streptomycin. Cholera toxin genotype 1 was present in the majority of the O139 isolates while few had type 3 or a novel type 4. In the cholera toxin encoding gene (ctx) restriction fragment length polymorphism, the majority of the isolates harbored three copies of CTX element, of which one was truncated. In this study, the ctx was detected for the first time in the small chromosome of V. cholerae O139 and one isolate harbored 5 copies of CTX element, of which 3 were truncated. The ribotype BII pattern was found in most of the O139 isolates. Three V. cholerae O139 isolated in 2001 had a new ribotype BVIII. Pulsed-field gel electrophoresis analysis revealed clonal variation in 2001 isolates compared to the 2004-2006 isolates. Molecular changes in V. cholerae O139 have to be closely monitored as this information may help in understanding the changing genetic features of this pathogen in relation to the epidemiology of cholera.

We identified 131 strains of Vibrio fluvialis among 400 nonagglutinating Vibrio spp. isolated from patients with diarrhea in Kolkata, India. For 43 patients, V. fluvialis was the sole pathogen identified. Most strains harbored genes encoding hemolysin and metalloprotease; this finding may contribute to understanding of the pathogenicity of V. fluvialis.