Extended spectrum beta-lactamase and fluoroquinolone resistance genes among Escherichia coli and Salmonella isolates from children with diarrhea, Burkina Faso.

BACKGROUND: The emergence and spread of multidrug-resistant gram-negative bacteria (MDR) has become a major public health concern worldwide. This resistance is caused by enzymes-mediated genes (i.e., extended spectrum beta-lactamases) that are common in certain Enterobacterioceae species. However, the distribution of these genes is poorly documented in Burkina Faso. This study aims to determine the prevalence and distribution of the resistant genes coding for broad spectrum beta-lactamases and quinolones in rural Burkina Faso. METHODS: Multiplex PCR assays were carried out to detect ESBL-encoding genes, including blaOXA, blaTEM, blaCTX-M, blaSHV. The assays also assessed the presence of quinolone resistance gene namely qnrA, qnrB and qnrS in the quinolone-resistance DEC and Salmonella strains. RESULTS: The Extended-Spectrum Beta-Lactamases (ESBL) resistance phenotype was reported in all the E. coli isolates (5/5). Cross-resistance phenotype to quinolones (CRQ) was shown by one Salmonella strain (1/9) and three E. coli (3/5). Cross-resistance phenotypes to fluoroquinolones (CRFQ) were harboured by one Salmonella (1/9) and carbapenemase phenotypes were detected in two E. coli strains (2/5). Whilst the blaOXA genes were detected in 100% (5/5) of E. coli isolates and in 33.33% (3/9) Salmonella isolates. One strain of E. coli (1/5) harbored the blaCTX-M gene and the qnrB gene simultaneously. CONCLUSIONS: This study identified ß-lactam (bla) and quinolone resistance (qnr) genes in multidrug-resistant E. coli and Salmonella spp. in rural Burkina Faso. Our finding which highlighted the enterobacteriaceae strains resistance to ß-lactams and quinolones are of high interest for adequate management of antimicrobial resistant genes outbreak in Burkina Faso.

Antimicrobial Resistance Profile of Salmonella Isolates in Chicken Carcasses in Dakar, Senegal.

The incidence of the Salmonella contamination of poultry products in Senegal is unknown. Salmonella contamination and antimicrobial drug resistance profiles in chicken carcasses were investigated. Between July 2012 and July 2013, three types of chicken carcasses (broilers, laying hens, and premises chickens) obtained from retailers in the markets of Dakar and its suburbs were tested for Salmonella contamination. Salmonella strains were isolated from 300 chicken carcasses according to International Organization for Standardization ISO 6579 (2002) guidelines. In these samples, 273 isolates were obtained, belonging to 22 serovars, and 53% samples were contaminated with at least 1 serovar. Standardized techniques were used for the susceptibility testing and serotyping of isolates. Hygiene conditions, in terms of the cleanliness of stalls, the packing of chicken carcasses in bags, and the maintenance of the cold chain at the stall, were moderately poor. The three serovars most frequently identified were Salmonella Istanbul (28%), Salmonella Brancaster (19%), and Salmonella Kentucky (13%). Overall, 21% of isolates were resistant to quinolones and fluoroquinolones. Serovar Istanbul was resistant to tetracycline (TE) and trimethoprim + sulfamethoxazole (SXT). Serovars Brancaster and Kentucky were resistant to betalactams and to quinolones or fluoroquinolones. The uncommon serovar Senftenberg had the strongest resistance profile, displaying resistance to betalactams including imipenem (IMP). Large numbers of isolates were resistant to TE (66%) and SXT (47%). Resistance to cephalosporins (5%), chloramphenicol (2%), gentamicin (8%), and IMP (1%) was less frequent. A large proportion of the broilers sold in Dakar markets were contaminated with Salmonella. This situation probably resulted from poor hygiene conditions in chicken farms and slaughterhouses and from breaks in the cold chain at some point in the distribution of poultry products.

Determining the Best Immunization Strategy for Protecting African Children Against Invasive Salmonella Disease.

Background: The World Health Organization recently prequalified a typhoid conjugate vaccine (TCV), recommending its use in persons ≥6 months to 45 years residing in typhoid fever (TF)-endemic areas. We now need to consider how TCVs can have the greatest impact in the most vulnerable populations. Methods: The Typhoid Fever Surveillance in Africa Program (TSAP) was a blood culture-based surveillance of febrile patients from defined populations presenting at healthcare facilities in 10 African countries. TF and invasive non-typhoidal Salmonella (iNTS) disease incidences were estimated for 0-10 year-olds in one-year age increments. Results: Salmonella Typhi and iNTS were the most frequently isolated pathogens; 135 and 94 cases were identified, respectively. Analysis from three countries was excluded (incomplete person-years of observation (PYO) data). Thirty-seven of 123 TF cases (30.1%) and 71/90 iNTS disease cases (78.9%) occurred in children aged <5 years. No TF and 8/90 iNTS infections (8.9%) were observed in infants aged <9 months. The TF incidences (/100 000 PYO) for children aged <1 year and 1 to <2 years were 5 and 39, respectively; the highest incidence was 304 per 100 000 PYO in 4 to <5 year-olds. The iNTS disease incidence in the defined age groups ranged between 81 and 233 per 100 000 PYO, highest in 1 to <2 year-olds. TF and iNTS disease incidences were higher in West Africa. Conclusions: High burden of TF detected in young children strengthens the need for TCV introduction. Given the concurrent iNTS disease burden, development of a trivalent vaccine against S. Typhi, S. Typhimurium, and S. Enteritidis may be timely in this region.

Corrigendum: Gene Expression in Class 2 Integrons Is SOS-Independent and Involves Two Pc Promoters.

[This corrects the article on p. 1499 in vol. 8, PMID: 28861047.].

Molecular Characterization of Diarrheagenic Escherichia Coli in Children Less Than 5 Years of Age with Diarrhea in Ouagadougou, Burkina Faso.

Diarrheagenic Escherichia coli (DEC) is important bacteria of children's endemic and epidemic diarrhea worldwide. The aim of this study was to determine the prevalence of DEC isolated from stool samples collected from children with acute diarrhea living in Ouagadougou, Burkina Faso. From August 2013 to October 2015, stool samples were collected from 315 children under 5 years of age suffering from diarrhea in the "Centre Médical avec Antenne Chirurgicale (CMA)" Paul VI and the CMA of Schiphra. E. coli were isolated and identified by standard microbiological methods, and the 16-plex PCR method was used to further characterize them. Four hundred and nineteen (419) E. coli strains were characterized, of which 31 (7.4%) DEC pathotypes were identified and classified in five E. coli pathotypes: 15 enteroaggregative E. coli (EAEC) (48.4%), 8 enteropathogenic E. coli (EPEC) (25.8%) with 4 typical EPEC and 4 atypical EPEC, 4 enteroinvasive E. coli (EIEC) (12.9%), 3 enterohemorrhagic E. coli (EHEC) 9.67%, and 1 enterotoxigenic E. coli (ETEC) 3.2%. The use of multiplex PCR as a routine in clinical laboratory for the detection of DEC would be a useful mean for a rapid management of an acute diarrhea in children.

Gene Expression in Class 2 Integrons Is SOS-Independent and Involves Two Pc Promoters.

Integrons are powerful bacterial genetic elements that permit the expression and dissemination of antibiotic-resistance gene cassettes. They contain a promoter Pc that allows the expression of gene cassettes captured through site-specific recombination catalyzed by IntI, the integron-encoded integrase. Class 1 and 2 integrons are found in both clinical and environmental settings. The regulation of intI and of Pc promoters has been extensively studied in class 1 integrons and the regulatory role of the SOS response on intI expression has been shown. Here we investigated class 2 integrons. We characterized the PintI2 promoter and showed that intI2 expression is not regulated via the SOS response. We also showed that, unlike class 1 integrons, class 2 integrons possess not one but two active Pc promoters that are located within the attI2 region that seem to contribute equally to gene cassette expression. Class 2 integrons mostly encode an inactive truncated integrase, but the rare class 2 integrons that encode an active integrase are associated with less efficient Pc2 promoter variants. We propose an evolutionary model for class 2 integrons in which the absence of repression of the integrase gene expression led to mutations resulting in either inactive integrase or Pc variants of weaker activity, thereby reducing the potential fitness cost of these integrons.

Identification of Atypical El TorV. cholerae O1 Ogawa Hosting SXT Element in Senegal, Africa.

Vibrio cholerae O1 is the causative agent of cholera with classical and El Tor, two well-established biotypes. In last 20 years, hybrid strains of classical and El Tor and variant El Tor which carry classical ctxB have emerged worldwide. In 2004-2005, Senegal experienced major cholera epidemic with a number of cases totalling more than 31719 with approximately 458 fatal outcomes (CFR, 1.44%). In this retrospective study, fifty isolates out of a total of 403 V. cholerae biotype El Tor serovar Ogawa isolates from all areas in Senegal during the 2004-2005 cholera outbreak were randomly selected. Isolates were characterized using phenotypic and genotypic methods. The analysis of antibiotic resistance patterns revealed the predominance of the S-Su-TCY-Tsu phenotype (90% of isolates). The molecular characterization of antibiotic resistance revealed the presence of the SXT element, a self-transmissible chromosomally integrating element in all isolates. Most of V. cholerae isolates had an intact virulence cassette (86%) (ctx, zot, ace genes). All isolates tested gave amplification with primers for classical CT, and 10/50 (20%) of isolates carried classical and El Tor ctxB. The study reveals the presence of atypical V. cholerae O1 El Tor during cholera outbreak in Senegal in 2004-2005.

First Description of the Extended Spectrum-Beta-Lactamase Gene blaCTX-M-109 in Salmonella Grumpensis Strains Isolated from Neonatal Nosocomial Infections in Dakar, Senegal.

Nosocomial infections are very common in African hospitals, particularly in neonatal units. These infections are most often caused by bacteria such as Escherichia coli, Klebsiella spp and Staphylococcus spp. Salmonella strains are rarely involved in nosocomial infections. Here, we report the first description of S. Grumpensis in neonatal infections in Senegal. Seventeen Salmonella strains were isolated from hospitalized infants' stool samples. The following resistance phenotype was described in strains: AMXRTICRCFR FOXRCFXRCTXRCAZRIMPSATMRNARNORRCIPRTMRGMRTERSXTR. All isolates were susceptible to imipenem, 15 out of 17 produced an extended spectrum ß-lactamase (ESBL). blaOXA-1, blaSHV-1, blaTEM-1, blaCTX-M1 genes were detected in strains 8, 13, 5 and 8, respectively. blaCTX-M1 sequencing revealed the presence of blaCTX-M-109. Thirteen of the 17 Salmonella Grumpensis strains were analyzed by PFGE. These 13 isolates belonged to a single pulsotype and were genotypically identical. This is the first report of neonatal S. Grumpensis infections in Senegal, and the first report of blaCTX-M-109 in the genus Salmonella.

A Multicountry Molecular Analysis of Salmonella enterica Serovar Typhi With Reduced Susceptibility to Ciprofloxacin in Sub-Saharan Africa.

BACKGROUND: Salmonella enterica serovar Typhi is a predominant cause of bloodstream infections in sub-Saharan Africa (SSA). Increasing numbers of S. Typhi with resistance to ciprofloxacin have been reported from different parts of the world. However, data from SSA are limited. In this study, we aimed to measure the ciprofloxacin susceptibility of S. Typhi isolated from patients with febrile illness in SSA. METHODS: Febrile patients from 9 sites within 6 countries in SSA with a body temperature of ≥38.0°C were enrolled in this study. Blood samples were obtained for bacterial culture, and Salmonella isolates were identified biochemically and confirmed by multiplex polymerase chain reaction (PCR). Antimicrobial susceptibility of all Salmonella isolates was performed by disk diffusion test, and minimum inhibitory concentrations (MICs) against ciprofloxacin were measured by Etest. All Salmonella isolates with reduced susceptibility to ciprofloxacin (MIC > 0.06 µg/mL) were screened for mutations in quinolone resistance-determining regions in target genes, and the presence of plasmid-mediated quinolone resistance (PMQR) genes was assessed by PCR. RESULTS: A total of 8161 blood cultures were performed, and 100 (1.2%) S. Typhi, 2 (<0.1%) Salmonella enterica serovar Paratyphi A, and 27 (0.3%) nontyphoid Salmonella (NTS) were isolated. Multidrug-resistant S. Typhi were isolated in Kenya (79% [n = 38]) and Tanzania (89% [n = 8]) only. Reduced ciprofloxacin-susceptible (22% [n = 11]) S. Typhi were isolated only in Kenya. Among those 11 isolates, all had a Glu133Gly mutation in the gyrA gene combined with either a gyrA (Ser83Phe) or gyrB mutation (Ser464Phe). One Salmonella Paratyphi A isolate with reduced susceptibility to ciprofloxacin was found in Senegal, with 1 mutation in gyrA (Ser83Phe) and a second mutation in parC (Ser57Phe). Mutations in the parE gene and PMQR genes were not detected in any isolate. CONCLUSIONS: Salmonella Typhi with reduced susceptibility to ciprofloxacin was not distributed homogenously throughout SSA. Its prevalence was very high in Kenya, and was not observed in other study countries. Continuous monitoring of antimicrobial susceptibility is required to follow the potential spread of antimicrobial-resistant isolates throughout SSA.

Utilization of Healthcare in the Typhoid Fever Surveillance in Africa Program.

BACKGROUND: Assessing healthcare utilization is important to identify weaknesses of healthcare systems, to outline action points for preventive measures and interventions, and to more accurately estimate the disease burden in a population. METHODS: A healthcare utilization survey was developed for the Typhoid Fever Surveillance in Africa Program (TSAP) to adjust incidences of salmonellosis determined through passive, healthcare facility-based surveillance. This cross-sectional survey was conducted at 11 sites in 9 sub-Saharan African countries. Demographic data and healthcare-seeking behavior were assessed at selected households. Overall and age-stratified percentages of each study population that sought healthcare at a TSAP healthcare facility and elsewhere were determined. RESULTS: Overall, 88% (1007/1145) and 81% (1811/2238) of the population in Polesgo and Nioko 2, Burkina Faso, respectively, and 63% (1636/2590) in Butajira, Ethiopia, sought healthcare for fever at any TSAP healthcare facility. A far smaller proportion-namely, 20%-45% of the population in Bissau, Guinea-Bissau (1743/3885), Pikine, Senegal (1473/4659), Wad-Medani, Sudan (861/3169), and Pietermaritzburg, South Africa (667/2819); 18% (483/2622) and 9% (197/2293) in Imerintsiatosika and Isotry, Madagascar, respectively; and 4% (127/3089) in Moshi, Tanzania-sought healthcare at a TSAP healthcare facility. Patients with fever preferred to visit pharmacies in Imerintsiatosika and Isotry, and favored self-management of fever in Moshi. Age-dependent differences in healthcare utilization were also observed within and across sites. CONCLUSIONS: Healthcare utilization for fever varied greatly across sites, and revealed that not all studied populations were under optimal surveillance. This demonstrates the importance of assessing healthcare utilization. Survey data were pivotal for the adjustment of the program's estimates of salmonellosis and other conditions associated with fever.

Validation and Identification of Invasive Salmonella Serotypes in Sub-Saharan Africa by Multiplex Polymerase Chain Reaction.

Salmonella enterica serovar Typhi and nontyphoidal Salmonella (NTS) cause the majority of bloodstream infections in sub-Saharan Africa; however, serotyping is rarely performed. We validated a multiplex polymerase chain reaction (PCR) assay with the White-Kauffmann-Le Minor (WKLM) scheme of serotyping using 110 Salmonella isolates from blood cultures of febrile children in Ghana and applied the method in other Typhoid Fever Surveillance in Africa Program study sites. In Ghana, 47 (43%) S. Typhi, 36 (33%) Salmonella enterica serovar Typhimurium, 14 (13%) Salmonella enterica serovar Dublin, and 13 (12%) Salmonella enterica serovar Enteritidis were identified by both multiplex PCR and the WKLM scheme separately. Using the validated multiplex PCR assay, we identified 42 (66%) S. Typhi, 14 (22%) S. Typhimurium, 2 (3%) S. Dublin, 2 (3%) S. Enteritidis, and 4 (6%) other Salmonella species from the febrile patients in Burkina Faso, Guinea-Bissau, Madagascar, Senegal, and Tanzania. Application of this multiplex PCR assay in sub-Saharan Africa could advance the knowledge of serotype distribution of Salmonella.

Bloodstream Infections and Frequency of Pretreatment Associated With Age and Hospitalization Status in Sub-Saharan Africa.

BACKGROUND: The clinical diagnosis of bacterial bloodstream infections (BSIs) in sub-Saharan Africa is routinely confused with malaria due to overlapping symptoms. The Typhoid Surveillance in Africa Program (TSAP) recruited febrile inpatients and outpatients of all ages using identical study procedures and enrollment criteria, thus providing an opportunity to assess disease etiology and pretreatment patterns among children and adults. METHODS: Inpatients and outpatients of all ages with tympanic or axillary temperatures of ≥38.0 or ≥37.5°C, respectively, and inpatients only reporting fever within the previous 72 hours were eligible for recruitment. All recruited patients had one blood sample drawn and cultured for microorganisms. Data from 11 TSAP surveillance sites in nine different countries were used in the analysis. Bivariate analysis was used to compare frequencies of pretreatment and BSIs in febrile children (<15 years old) and adults (≥15 years old) in each country. Pooled Cochran Mantel-Haenszel odds ratios (ORs) were calculated for overall trends. RESULTS: There was no significant difference in the odds of a culture-proven BSI between children and adults among inpatients or outpatients. Among both inpatients and outpatients, children had significantly higher odds of having a contaminated blood culture compared with adults. Using country-pooled data, child outpatients had 66% higher odds of having Salmonella Typhi in their bloodstream than adults (OR, 1.66; 95% confidence interval [CI], 1.01-2.73). Overall, inpatient children had 59% higher odds of pretreatment with analgesics in comparison to inpatient adults (OR, 1.59; 95% CI, 1.28-1.97). CONCLUSIONS: The proportion of patients with culture-proven BSIs in children compared with adults was similar across the TSAP study population; however, outpatient children were more likely to have Salmonella Typhi infections than outpatient adults. This finding points to the importance of including outpatient facilities in surveillance efforts, particularly for the surveillance of typhoid fever. Strategies to reduce contamination among pediatric blood cultures are needed across the continent to prevent the misdiagnosis of BSI cases in children.

MALDI-TOF identification of the human Gut microbiome in people with and without diarrhea in Senegal.

BACKGROUND: In Africa, there are several problems with the specific identification of bacteria. Recently, MALDI-TOF mass spectrometry has become a powerful tool for the routine microbial identification in many clinical laboratories. METHODOLOGY/PRINCIPAL FINDINGS: This study was conducted using feces from 347 individuals (162 with diarrhea and 185 without diarrhea) sampled in health centers in Dakar, Senegal. Feces were transported from Dakar to Marseille, France, where they were cultured using different culture conditions. The isolated colonies were identified using MALDI-TOF. If a colony was unidentified, 16S rRNA sequencing was performed. Overall, 2,753 isolates were tested, allowing for the identification of 189 bacteria from 5 phyla, including 2 previously unknown species, 11 species not previously reported in the human gut, 10 species not previously reported in humans, and 3 fungi. 2,718 bacterial isolates (98.8%) out of 2,750 yielded an accurate identification using mass spectrometry, as did the 3 Candida albicans isolates. Thirty-two bacterial isolates not identified by MALDI-TOF (1.2%) were identified by sequencing, allowing for the identification of 2 new species. The number of bacterial species per fecal sample was significantly higher among patients without diarrhea (8.6±3) than in those with diarrhea (7.3±3.4; P = 0.0003). A modification of the gut microbiota was observed between the two groups. In individuals with diarrhea, major commensal bacterial species such as E. coli were significantly decreased (85% versus 64%), as were several Enterococcus spp. (E. faecium and E. casseliflavus) and anaerobes, such as Bacteroides spp. (B. uniformis and B. vulgatus) and Clostridium spp. (C. bifermentans, C. orbiscindens, C. perfringens, and C. symbosium). Conversely, several Bacillus spp. (B. licheniformis, B. mojavensis, and B. pumilus) were significantly more frequent among patients with diarrhea. CONCLUSIONS/SIGNIFICANCE: MALDI-TOF is a potentially powerful tool for routine bacterial identification in Africa, allowing for a quick identification of bacterial species.

Community-acquired diarrhea among children and adults in urban settings in Senegal: clinical, epidemiological and microbiological aspects.

BACKGROUND: Only limited data are available relating to the etiology of diarrhea in children and adults in Senegal. The aim of this prospective study was to describe the epidemiology and etiology of community-acquired diarrheal infections in children and adults living in urban settings. METHODS: A prospective study was carried out from March 2009 to December 2010, in the urban region of Dakar, Senegal. Patients with acute diarrhea were enrolled, interviewed to collect their clinical history, and their stools were tested for bacteria, virus and parasites. RESULTS: A total of 223 patients (including 112 children younger than five years old) with diarrhea were included. At least one enteropathogen was detected in 81% (180/223) of the patients: 29% (64/223) had bacterial infections (mainly diarrheagenic E. coli and Shigella spp), 21% (39/185) viral infections (mainly rotavirus) and 14% (31/223) parasitic infections. Co-infection was identified in 17.8% (32/180) of the patients. Viral infection was significantly more frequent in children under five years old during the dry season. Bacteria and parasites were equally frequent in all age groups. There was a seasonal variation of bacterial infections during the study period, with a higher proportion of infections being bacterial, and due to Salmonella spp. in particular, during the rainy season. CONCLUSION: Our study suggests that in urban settings in Senegal, rotavirus is the principal cause of pediatric diarrhea during the dry season and that the proportion of bacterial infections seems to be higher during the rainy season. Further work is needed to document the burden of diarrheal diseases in sub-Saharan urban communities and to identify risk factors, including those linked to the rapid and unplanned urbanization in Africa.

Carbapenem resistance and Acinetobacter baumannii in Senegal: the paradigm of a common phenomenon in natural reservoirs.

Incidence of carbapenem-resistant Acinetobacter baumannii is rising in several parts of the world. In Africa, data concerning this species and its resistance to carbapenems are limited. The objective of the present study was to identify the presence of A. baumannii carbapenem-resistant encoding genes in natural reservoirs in Senegal, where antibiotic pressure is believed to be low. From October 2010 to January 2011, 354 human head lice, 717 human fecal samples and 118 animal fecal samples were screened for the presence of A. baumannii by real time PCR targeting bla(OXA51-like) gene. For all samples positive for A. baumannii, the carbapenemase-hydrolysing oxacillinases bla(OXA23-like) and bla(OXA24-like) were searched for and sequenced, and the isolates harbouring an oxacillinase were genotyped using PCR amplification and sequencing of recA gene. The presence of A. baumannii was detected in 4.0% of the head lice, in 5.4% of the human stool samples and in 5.1% of the animal stool samples tested. No bla(OXA24) gene was detected but six fecal samples and three lice were positive for bla(OXA23-like) gene. The bla(OXA23-like) gene isolated in lice was likely a new oxacillinase sequence. Finally, the A. baumannii detected in stools were all of recA genotype 3 and those detected in lice, of recA genotype 4. This study shows for the first time a reservoir of bla(OXA23-like)-positive gene in human head lice and stool samples in Senegal.

High prevalence of trimethoprim-resistance cassettes in class 1 and 2 integrons in Senegalese Shigella spp isolates.

BACKGROUND: Integrons have a well-established role in the dissemination of resistance among Gram-negative pathogens and are thus a useful marker of antibiotic resistance. Shigellae are noteworthy for their multiple drug resistance, having gradually acquired resistance to most widely use and inexpensive antimicrobial drugs. METHODOLOGY: A total of 32 Shigella strains belonging to serotypes flexneri, dysenteriae, and boydii 20, a new Shigella serovar, resistant to at least four antibiotics were analyzed by molecular techniques. RESULTS: Class 1 integrons were the most prevalent (92.8%); class 2 integrons were found in 16 strains (57.1%). Fifty percent of the strains harboured both class 1 and 2 integrons (intI1 and intI2 genes); this combination of integrase genes was most prevalent in S. boydii 20 and S. dysenteriae strains. The class 1 integrons detected contained dfr and aadA cassettes, alone or in combination (dfrA5/dfrA15, or dfrA15-aadA1, dfrA1-aadA2), and an atypical cassette array with an insertion sequence (oxa30-aadA1-IS1). For class 2 integrons, we detected either the same cassettes as those found in Tn7 (dfrA1-sat1-aadA1-orfX) or truncated class 2 integrons without aadA1 or orfX. The tns genes were absent from all class 2 integrons.The distribution of integrons among RAPD profiles and serotypes revealed a clonal spread of integrons into serotypes and a transfer of integrons between different serotypes. CONCLUSIONS: The detection of integrons in a new Shigella serovar, in addition with a high integron prevalence among Shigella strains, confirms the propensity of shigellae to acquire and disseminate resistance determinants.

Antibiotic susceptibility of Helicobacter pylori isolates in Dakar, Senegal.

BACKGROUND: Helicobacter pylori is the primary cause of peptic ulcer disease and an etiologic agent in the development of gastric cancer. A high frequency of H. pylori infection has been reported from resource-poor regions. H. pylori infection is curable with regimens of multiple antimicrobial agents. However, antibiotic resistance is a leading cause of treatment failure. In Africa, there are very little data concerning the susceptibility of H. pylori isolates to antibiotics. METHODOLOGY: H. pylori isolates from gastric biopsies from outpatients > or = 18 years old affected by a gastro-duodenal ulcer were used in this study. Susceptibility testing was performed for amoxicillin, ciprofloxacin and metronidazole by using the Epsilometer test (E-test) method. RESULTS: H. pylori strains were isolated from 40 patients of whom 36 were diagnosed as having duodenal ulcer, two with gastric ulcer, and two with gastro-duodenal ulcer. Thirty-six (90%) of the isolates were resistant to metronidazole (MICs > or = 8 microg/l), whereas all isolates were susceptible to amoxicillin (MICs < or = 0.5 microg/ml) and ciprofloxacin (MICs < or = 1 microg/ml). CONCLUSION: These data suggest that metronidazole should not be used therapeutically among Senegalese patients in first-line therapy, while ciprofloxacin could be recommended in association with amoxicillin and a proton pump inhibitor in Senegal.

Role of deoxyribose catabolism in colonization of the murine intestine by pathogenic Escherichia coli strains.

We previously suggested that the ability to metabolize deoxyribose, a phenotype encoded by the deoK operon, is associated with the pathogenic potential of Escherichia coli strains. Carbohydrate metabolism is thought to provide the nutritional support required for E. coli to colonize the intestine. We therefore investigated the role of deoxyribose catabolism in the colonization of the gut, which acts as a reservoir, by pathogenic E. coli strains. Molecular and biochemical characterization of 1,221 E. coli clones from various collections showed this biochemical trait to be common in the E. coli species (33.6%). However, multivariate analysis evidenced a higher prevalence of sugar-metabolizing E. coli clones in the stools of patients from countries in which intestinal diseases are endemic. Diarrhea processes frequently involve the destruction of intestinal epithelia, so it is plausible that such clones may be positively selected for in intestines containing abundant DNA, and consequently deoxyribose. Statistical analysis also indicated that symptomatic clinical disorders and the presence of virulence factors specific to extraintestinal pathogenic E. coli were significantly associated with an increased risk of biological samples and clones testing positive for deoxyribose. Using the streptomycin-treated-mouse model of intestinal colonization, we demonstrated the involvement of the deoK operon in gut colonization by two pathogenic isolates (one enteroaggregative and one uropathogenic strain). These results, indicating that deoxyribose availability promotes pathogenic E. coli growth during host colonization, suggest that the acquisition of this trait may be an evolutionary step enabling these pathogens to colonize and persist in the mammalian intestine.