Alternative observational designs to estimate the effectiveness of one dose of oral cholera vaccine in Lusaka, Zambia.

We conducted a matched case-control (MCC), test-negative case-control (TNCC) and case-cohort study in 2016 in Lusaka, Zambia, following a mass vaccination campaign. Confirmed cholera cases served as cases in all three study designs. In the TNCC, control-subjects were cases with negative cholera culture and polymerase chain reaction results. Matched controls by age and sex were selected among neighbours of the confirmed cases in the MCC study. For the case-cohort study, we recruited a cohort of randomly selected individuals living in areas considered at-risk of cholera. We recruited 211 suspected cases (66 confirmed cholera cases and 145 non-cholera diarrhoea cases), 1055 matched controls and a cohort of 921. Adjusted vaccine effectiveness of one dose of oral cholera vaccine (OCV) was 88.9% (95% confidence interval (CI) 42.7-97.8) in the MCC study, 80.2% (95% CI: 16.9-95.3) in the TNCC design and 89.4% (95% CI: 64.6-96.9) in the case-cohort study. Three study designs confirmed the short-term effectiveness of single dose OCV. Major healthcare-seeking behaviour bias did not appear to affect our estimates. Most of the protection among vaccinated individuals could be attributed to the direct effect of the vaccine.

Non-O1, non-O139 Vibrio cholerae bacteraemia: case report and literature review.

Non-O1, non-O139 Vibrio cholerae (NOVC) are increasingly frequently observed ubiquitous microorganisms occasionally responsible for intestinal and extra-intestinal infections. Most cases involve self-limiting gastroenteritis or ear and wound infections in immunocompetent patients. Bacteraemia, which have been described in patients with predisposing factors, are rare and poorly known, both on the clinical and therapeutic aspects. We describe a case of NOVC bacteraemia and a systematic literature review in PubMed conducted up to November 2014 using a combination of the following search terms: "Vibrio cholerae non-O1" and "bacter(a)emia". The case was a 70 year-old healthy male subject returning from Senegal and suffering from NOVC bacteraemia associated with liver abscesses. Disease evolution was favourable after 2 months' therapy (ceftriaxone then ciprofloxacin). Three hundred and fifty cases of NOVC bacteraemia have been identified in the literature. The majority of patients were male (77 %), with a median age of 56 years and presenting with predisposing conditions (96 %), such as cirrhosis (55 %) or malignant disease (20 %). Diarrhoea was inconstant (42 %). Mortality was 33 %. The source of infection, identified in only 25 % of cases, was seafood consumption (54 %) or contaminated water (30 %). Practitioners should be aware of these infections, in order to warn patients with predisposing conditions, on the risk of ingesting raw or undercooked seafood or bathing in potentially infected waters.

Prevalence of Vibrio spp. in raw shrimps (Parapenaeus longirostris) and performance of a chromogenic medium for the isolation of Vibrio strains.

UNLABELLED: Vibrios are natural inhabitants of estuarine ecosystems and some species may pose public health problem as agents of sporadic or collective food-borne infections associated with the consumption of fish or shellfish. Samples of raw shrimp (n = 299), fished in coastal areas of the city of Agadir, Morocco, and collected from its fish marketplace, were examined for the presence of pathogenic vibrios. Microbiological analysis was carried out according to a protocol using thiosulphate citrate bile sucrose (TCBS) agar and CHROMagar Vibrio (CV) as selective media. Presumptive-positive colonies were identified by biochemical and species-specific PCR systems, and further tested by PCR for the presence of pathogenicity factors. The overall prevalence of Vibrio spp. in shrimps was 55·8%. Vibrio parahaemolyticus was recovered from 25 of 299 samples (8·4%), Vibrio cholerae from six samples (2%) and Vibrio alginolyticus from 161 samples (53·8%). No virulence genes were found among V. parahaemolyticus and V. cholerae isolates. The CHROMagar Vibrio plating medium was found to be more efficient than the Thiosulphate Citrate Bile salt Sucrose (TCBS) Agar in the isolation of Vibrio organisms. SIGNIFICANCE AND IMPACT OF THE STUDY: A significant proportion of shrimps marketed and consumed in Morocco are caught in the coastal region of the city of Agadir. This study provides interesting data of prevalence of Vibrio spp. in raw shrimps as well as better understanding of their potential virulence. It is apparent from this study that genes and primers used in multiplex PCR for identification and detection of virulence factors, can be used to monitor shrimps for the presence of potentially pathogenic strains of Vibrio cholerae and Vibrio parahaemolyticus. The results highlight the added value of using a chromogenic medium for research and isolation of pathogenic Vibrio in seafood, more specific and accurate than TCBS.

Risk of Vibrio transmission linked to the consumption of crustaceans in coastal towns of Côte d'Ivoire.

The purpose of this study was to assess the risk of Vibrio spp. transmission from crustaceans to humans in two coastal towns of Côte d'Ivoire. Bacteriologic analysis was performed on 322 crustacean samples obtained from six markets in Abidjan and one in Dabou. Suspected Vibrio colonies were identified by morphological, cultural, biochemical, and molecular tests and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. PCR assays were used to further characterize Vibrio strains. A survey on consumption of crustaceans was conducted among 120 randomly selected households in Abidjan. Overall, Vibrio spp. were isolated from 7.8% of the crustacean samples studied, at levels as high as 6.3 log CFU/g. Of the Vibrio strains identified, 40% were V. alginolyticus, 36% were V. parahaemolyticus, and 24% were nontoxigenic V. cholerae; the latter two species can cause mild to severe forms of seafood-associated gastroenteritis. Among interviewed households, 11.7% reported daily consumption of crustaceans, confirming the high probability of exposure of human population to Vibrio spp., and 7.5% reported symptoms of food poisoning after consumption of crustaceans. The absence of genes encoding major virulence factors in the studied strains, i.e., cholera toxin (ctxA and ctxB) in V. cholerae and thermostable direct hemolysin (tdh) and thermostable direct hemolysin-related hemolysin (trh) in V. parahaemolyticus, does not exclude the possibility of exposure to pathogenic strains. However, human infections are not common because most households (96.7%) boil crustaceans, usually for at least 45 min (85.9% of households) before consumption.

Evaluation of most-probable-number-PCR method with internal amplification control for the counting of total and pathogenic Vibrio parahaemolyticus in frozen shrimps.

The most-probable-number (MPN) method is often time-consuming for the isolation, detection, and quantification of Vibrio parahaemolyticus from natural sources. MPN counting of V. parahaemolyticus bacteria usually involves the isolation of typical V. parahaemolyticus colonies on selective medium, with subsequent confirmation by biochemical identification. In this study, we evaluated the use of a PCR on MPN enrichment cultures (MPN-PCR) for the direct detection of total and pathogenic V. parahaemolyticus cells in frozen shrimp. This reaction targeted the R72H, tdh, and trh sequences. An internal amplification control was added to the samples before R72H amplification. There was an excellent correlation between the results of the two methods for artificially inoculated and natural shrimp samples. Of 36 natural samples, 28 tested positive for the presence of V. parahaemolyticus, with an MPN value of 2 × 10(-1) to 9.2 × 10(1) per g. No pathogenic V. parahaemolyticus cells were detected. The test had a detection limit of one V. parahaemolyticus organism per g and was completed within two working days. These results support the use of the combination of PCR with MPN for the detection of total or potentially pathogenic V. parahaemolyticus cells in frozen shrimp.

Total and pathogenic Vibrio parahaemolyticus in shrimp: fast and reliable quantification by real-time PCR.

Vibrio parahaemolyticus is found in aquatic environments and is the leading cause of gastroenteritis due to seafood consumption worldwide. We evaluated a quantitative real-time PCR (Q-PCR) assay with hydrolysis probes, to determine whether this method could be used for the efficient counting of total, tdh and trh-positive V. parahaemolyticus in shrimps. We assessed the specificity of this assay, using 62 strains from 12 non target bacterial species of the Vibrio, Photobacterium, Shewanella and Aeromonas genera. Only V. parahaemolyticus with the appropriate target gene generated a fluorescent signal. We assessed the robustness of this assay, by analyzing spiked shrimps by Q-PCR and traditional culture methods, using most probable number (MPN)-PCR. After a 6h enrichment period, the assay successfully detected total and pathogenic V. parahaemolyticus in shrimps samples spiked with less than 5 V. parahaemolyticuscells/g of shrimp. The Q-PCR results obtained were compared with those obtained by most probable number (MPN)-PCR format. An excellent correlation between the two methods was observed in all cases (R² > 0.9742). The application of this Q-PCR assay to 85 natural shrimp samples also resulted in the successful quantification of V. parahaemolyticus in this matrix, and the counts obtained were correlated with those obtained by (MPN)-PCR (P=0.2598). Thus, this rapid and sensitive Q-PCR can be used to quantify V. parahaemolyticus in natural shrimp samples. This assay could be proposed, in response to the demands of the European Commission, as a tool for testing for the presence of vibrios in crustaceans, making it possible to legislate in this domain.

Non-O1, non-O139 Vibrio cholerae bacteraemia in a cirrhotic patient.

Vibrio cholerae serogroups O1 or O139 are the aetiological agents of cholera. The pathogenicity of non-O1, non-O139 V. cholerae is less well known. These worldwide bacteria are responsible for gastrointestinal infections or, more rarely, bacteraemia in patients with an underlying disease, leading to life-threatening complications. We report a case of non-O1, non-O139 V. cholerae bacteraemia due to a haemolytic strain in a cirrhotic patient. Early antibiotherapy allowed a good outcome. The aim of this case report is to underline the virulence of non-choleragenic Vibrio strains, possibly linked to haemolysin production, and the potential danger of consuming undercooked seafood or exposing wounds to sea water in cirrhotic patients.

[Cases of imported cholera in France, summer 2005. A. Tarantola for the incident management teams]. / Cas de choléra d'importation en France, été 2005. A. Tarantola pour les groupes de gestion des incidents.

Cholera is a bacterial infection, which causes digestive symptoms and massive diarrhoea. It may lead to dehydration and death if appropriate medical management is not rapidly initiated. Most cases of infection by choleric vibrio, however, remain symptom-free or may mimic common gastroenteritis. A review of two cases of imported cholera in France in the summer of 2005 and the community- and hospital-based investigation, which they triggered, enabled the incident management teams to assess risks of transmission. There were no secondary cases among 58 hospital contacts and 15 family contacts of the cases. Clinicians will find a discussion of possible clinical presentations and the risk of secondary transmission, in the context of progressing epidemics in countries, which have maintained close ties with France.

[Vibrio vulnificus septicemia transmitted through a wound caused by a crustacea]. / Septicémie à Vibrio vulnificus secondaire à une blessure par écrevisse.

INTRODUCTION: Vibrio vulnificus proliferates during the summer in salt water where it infects the crustaceans. Expression of its pathogenicity depends on the underlying condition and mode of contamination. OBSERVATION: A 65 year-old man presented with a Vibrio vulnificus septicaemia of cutaneous origin, transmitted when he cut himself with a crawfish. The severity of the infection was enhanced by severe immuno-depression and haemochromatosis. The infection regressed with appropriate antibiotherapy. COMMENTS: Severe V. vulnificus infections are rare. Depending on the underlying condition and mode of contamination, one can distinguish between benign gastro-enteritis, local occasionally devastating infections and usually fatal septicaemia. CONCLUSION: Even the most severe forms of V. vulnificus infections may be cured with early and well adapted anti-infectious treatment.

Ribotyping of Chryseobacterium meningosepticum: its use as an epidemiological tool and its correlation with serovars.

Chryseobacterium meningosepticum (basonym, Flavobacterium meningosepticum King 1959) is associated with neonatal meningitis and is isolated from normal and immunocompromised adults. AAF-labelled Escherichia coli 16 + 23S rRNA was used as a probe for ribotype analysis of 92 clinical isolates from tracheal exsudate, blood culture, cerebrospinal fluid, urine and pus. The 92 isolates belonged to the 15 described serovars of C. meningosepticum, and included 21 strains isolated during an outbreak in an intensive care unit, all belonging to serovar G. Three restriction endonucleases, EcoRI, HindIII and PstI, were selected for use in ribotyping after preliminary experiments. Epidemiologically unrelated isolates were discriminated by ribotyping and could be classified into 48 ribotypes according to the hybridization banding patterns obtained after restriction with the three enzymes. Strains which were not discriminated by combined ribotype analysis belonged to the same serovar, and were of identical geographic origin. In one case, analysis with an additional enzyme, PvuII, was necessary for separating strains from two different serovars. However, three strains from different serovars (two isolated from the same place and one elsewhere within eight years) showed the same combined ribotype. Analysis of the rRNA gene patterns revealed 6 different patterns for clinical isolates of the outbreak, suggesting unrelated sources of infection. In three patients, isolation of C. meningosepticum with different combined ribotypes suggested superinfection. Ribotyping enabled differentiation between isolates belonging to the same serovar as well as between isolates of different serovars and provided a useful molecular epidemiological tool for the study of C. meningosepticum. Combined ribotype analysis with several restriction endonucleases increased the discriminating power of the method. However, there was only a partial correlation between serovars and the extent of DNA relatedness.

BamHI restriction endonuclease analysis of Yersinia ruckeri plasmids and their relatedness to the genus Yersinia 42- to 47-megadalton plasmid.

The plasmid profile and BamHI restriction pattern of 17 sorbitol-negative and 1 sorbitol-positive French Yersinia ruckeri strain of the American type strain were studied. The 17 sorbitol-negative strains and the American strain harbored a 62-megadalton (MDa) plasmid with an identical BamHI restriction pattern. Southern hybridization indicated that this 62-MDa plasmid is common among these various strains. The sorbitol-positive strain had four plasmid bands (70, 62, 32, and 25 MDa), and there was no comigration of the DNA fragments of these cleaved plasmids with the fragments of the 62-MDa plasmid. Hybridization of these restricted plasmids with the common 62-MDa plasmid showed a weak DNA homology. The Y. ruckeri plasmid (62 MDa) had a different molecular weight than the virulence plasmid (42 to 47 MDa) of the genus Yersinia, and they had different BamHI restriction patterns. Furthermore, no sequence of the Y. ruckeri plasmid DNA was recognized after Southern hybridization when the 47-MDa plasmid of Y. enterocolitica was used as a probe.

Lack of correlation between plasmid-encoded outer membrane proteins and virulence of Yersinia enterocolitica.

When various strains of Yersinia enterocolitica belonging to serovars 0:1,3, 0:3, 0:5,27, 0:9 and 0:Tacoma harbouring 44- to 47-Md plasmids, or their spontaneously cured isogenic pairs, were inoculated (i. v., with standardized inocula) into Swiss female mice, the kinetics of bacterial survival in the spleen were followed, revealing inoculum destruction within 15 days. With both strains Ye8081 and WA (0:8, harbouring a 42-Md plasmid), the kinetics of bacterial growth ended in the death of mice. The early spleen bacterial uptake was the same with all strains studied, whether plasmid-harbouring or plasmid-less derivatives. In this study, virulent strain Ye8081 and both low-virulent IP383 and Ye9576 were shown to synthesize antigenically related outer membrane polypeptides plasmid-encoded at 37 degrees C and previously considered as virulence determinants.

Role of the virulence-associated plasmids of Yersinia enterocolitica on its immunogenicity against Y. pestis.

Forty-two strains selected from various serovars of Yersinia enterocolitica were studied for their ability to induce cross-protection against Y. pestis. Only primo-infected mice (i.v.) with inocula prepared from strains of Y. enterocolitica belonging to serovars 0:3, 0:9 and 0:5, 27 harbouring a 47-Mdal virulence-associated plasmid were resistant to Y. pestis. The spontaneously cured (plasmid-less) derivatives of these strains had lost the capacity to induce this cross-immunity.