Bibliographie courante des traveaux du centre (1958-1978)

This publication is an up-to-date review of the papers published by the researchers of the Oceanographic Research Center of Abidjan, since its beginnings (1958-1978)

Performance of selective media for E. coli O157, using non-sorbitol fermenting strains and physiological characters of shiga-toxin producing species isolated in Côte d'Ivoire

Performance of three selective media, tmperature and pH effects on growth of E. coli O157:H7 isolated in Ivory Coast were investigated. Thirty-eight (38) non-sorbitol fermenting E. coli were characterized by serotyping, detection of shiga-toxin gene (PCR) and plating on SMAC, VRMUG and BCMtm media for Performance evaluation. Temperature and pH effects on E. coli O157:H7 were measured in varied culture conditions. All culture media were sensitive (100%) for the growth of E. coli O157. Their specificities were 97.3, 94.7 and 50.7% respectively for VRMUG, BCMtm and SMAC media. Predictive value for VR-MUG medium was 66%, whereas that for SMAC medium was only 5.4%. Serotype O157:H7 E. coli population grew slightly at 42 °C and didn’t grow under acid conditions (pH 4.5, 3.5). The performance of the culture media evaluatedand the physiological data obtained for E. coli O157:H7 during this study would contribute to improve both isolation and identification methods of the pathovars.© 2010 International Formulae Group. All rights reserved.Keywords: E. coli O157H7, performance, culture medium, shiga-toxin, pH, temperatur

Activity of the corpora allata of adult female Leucophaea maderae

In the cockroach Leucophaea maderae, a centre in the brain controls the female's acceptance of courting males. This centre is affected by starvation. A brief exposure to food can induce mating but is inadequate for oocyte development. In fed L. maderae there appears to be a synergistic action of nutrition and mating in controlling the rate of oocyte development. Mating (mechanical) and feeding (chemical) stimuli are both required for activating the corpora allata (CA) to their fullest extent so that the oocytes mature at their maximum rate. A rate of 0.4 mm/day of oocyte growth was recorded. Activity of CA in vitro was quantified using a radiochemical assay. In starved virgin females, no detectable activity was recorded by our assay conditions. The CA were virtually inactive and yolk was not deposited in the oocytes; mating had no effect on CA and oocyte development in starved females. Experiments with fed females showed that feeding increased CA activity to about 2 pmol JH-III/pair/hr of glands until the roaches were mated (11-12 days after eclosion). After mating, the activity of the CA increased over a period of 9 days to a peak of 52.7± 1.5 pmol JH-III/hr/pair of glands. Farnesol stimulation experiments showed that the inhibition of juvenile hormone synthesis in virgin females was exerted early in the biosynthetic pathway

Isolation and characterization of Yersinia intermedia strains from pig tonsils in Abidjan, Côte d’Ivoire

A total of 150 samples of pig tonsils were collected from slaughterhouse in Abidjan; the pigs were from pig farms located in different areas of Côte d’Ivoire. Samples were examined for the presence of Yersinia intermedia. Optimal recovery of Y. intermedia was achieved using two step enrichment procedures based on pre-enrichment in trypticase soya broth at 28 °C for 24 h, followed by cold enrichment method at 4 °C for 21 days in phosphate buffered saline broth. Then, Aulisio’s alkali treatment method was performed before streaking onto MacConkey agar. Six strains of Yersinia intermedia were isolated and tested for the following characteristics associated to the virulence in Y. enterocolitica such as pyrazinamidase activity and autoagglutinability. All the six strains were all positive for the pyrazinamidase test and four of them were autoagglutinable. Four strains were biotype 4/autoagglutinable and two were biotype 5/O:7,8-8-8,19. All the six strains of Yersinia intermedia were rhamnose negative and not motile at 25 °C. The results of antimicrobial resistance showed that all the strains presented multiple antibiotic resistance. The results indicate that 4% of pig tonsils from different farms collected at the slaughterhouse were contaminated with Yersinia intermedia. This study is the first which shows the presence of Yersinia intermedia in pigs in Côte d’Ivoire.Keywords: Yersinia intermedia, pig tonsils, prevalence, biotype, antibiotic resistance, Côte d’Ivoir

Virulence, serotype and phylogenetic groups of diarrhoeagenic Escherichia coli isolated during digestive infections in Abidjan, Côte d’Ivoire

The virulence, serotype and phylogenetic traits of diarrhoeagenic Escherichia coli were detected in 502 strains isolated during digestive infections. Molecular detection of the target virulence genes, rfb gene of operon O and phylogenetic grouping genes Chua, yjaA and TSPE4.C2 was performed. Prevalence of strains harbouring virulent genes was 7.8%. The virulent genes eaeA, bfp, stx2, st1, lt, aggA, east1, ipaH, ial, cnf1 and afa were detected. EAEC (36%) and both EPEC and ATEC (25.6%) are the most detected pathovars (p<0.05). STEC (5.1%), NFEC (7.7) and DAEC (7.7) are less represented. Serogroups are overall diversified (89%), however, serogroups O157, O103 and O86, previously known to be associated with virulence were revealed. Most of the E. coli pathovars (53%) belonged to phylogenetic group A and in decreasing importance order, to D (23.5%), B1 (11.7%) and B2 (11.7%) groups. The study shows a diversified population of intestinal strains (84.6%), with a low phenotypic and phylogenetic link lower (p<0.05). Due to the great diversity of pathotypes, continuous monitoring should be implemented to identify risk factors and major pathways of contamination that help defining strategies to reduce infections associated with E. coli.Keywords: Escherichia coli, virulence gene, serogroup, phylogenetic group, diversityAfrican Journal of Biotechnology, Vol. 13(9), pp. 998-1008, 26 February, 201

Analyse des risques microbiens du lait cru local à Abidjan (Côte d’Ivoire)

The hygiene practices during milking, the microbiological and chemical quality of cow raw milk from production to sale were studied in 15 small dairies in Abidjan. The analysis of raw milk quality showed that 81.5% of raw milk taken udders of cow were of good quality, against 35.30% for raw milk on sale. The average of Coliforms was 8.7.103 cfu/ml for raw milk taken cow’s udder, 3.2.105 cfu/ml for raw milk in tank and 9.9.105 cfu/ml for raw milk sales. The udders of cows, hands of milkers were identified as primary sources of milk contamination. The utensils (farmer, vendor) and environment were identified as major sources of secondary contamination. In addition, 24.7% of milk contained antibiotics and 50% of raw milk on sale were wet with water. The occurrence of food borne diseases is significantly related to the behavior of consumption of unpasteurized raw milk (P<0.05) with a relative risk of 2.81 (95%CI: 1.17 – 6.78). The zootechnical management of actors and popularization of good hygiene practices throughout the production chain are necessary for improvement of local milk quality