Bactericidal activity of human sera against Salmonella Typhiand Salmonella paratyphi A,B,C

Objectives: To determine the sensitivity of Salmonella typhi and paratyphi A,B,C, to normal human blood serum; and assess the role of blood groups (ABO system), Complement and Immunoglobulin in the resistance or susceptibility of Salmonella typhi and Salmonellaparatyphi A,B,C infections.Design: Cross sectional study.Subjects: Ninety-six apparently healthy males and females volunteers, aged 18-24 years.Main outcome measures: Resistance of Salmonella typhi and Salmonella paratyphi A,B,C infections may be blood group and immune status dependent.Results: Blood group B was most resistant to Salmonella typhi and Salmonella paratyphi A,B,C while blood group O showed least resistance (51.9%) and (22.2%) for Salmonella typhi and Salmonella paratyphi A,B,C. There was no difference in resistance pattern when blood was pooled in respect to their group types. Age or sex of the blood donors had no effect on the bactericidal activity of the sera.Conclusion: Blood group is an important factor in the susceptibility or resistance of an individual to Salmonella typhi and paratyphi infections. Individuals of blood group O are likely to be more susceptible to infections caused by Salmonella typhi and paratyphi A,B,C

Antimicrobial susceptibility profile of isolates of Aeromonas hydrophila from different sources: use of amylase activity as end-point indicator

Antimicrobial susceptibility profile of 45 Aeromonas hydrophila isolates (from different sources) to 11 commonly used antimicrobial agents was determined by agar diffusion technique. Minimal inhibitory concentrations (MICs) of antimicrobial drugs were also determined using amylase property of Aeromonas as end-point indicator in broth dilution models. Results showed that there was no significant difference in the antimicrobial susceptibility of Aeromonas from clinical and other sources (P > 0.05). All the isolates (100%) were susceptible to quinolones (Ciprofloxacin and Ofloxacin), Gentamicin and Nitrofurantoin. Over 80% of the isolates were susceptible to Tetracycline, Streptomycin, Nalidixic acid and Ceftazidime. Ofloxacin and Gentamicin had the lowest “MIC90” values (0.25μg/ml and 0.5μg/ml respectively). The isolates were markedly resistant to Ampicillin (42 or 93%), with “MIC90” value of 128μg/ml; forty (89%) of the 45 isolates produced detectable levels of β-lactamase enzyme. The use of Amylase activity of Aeromonas for MIC determination was comparable, in efficiency, with the conventional visual estimation in broth dilution model. Keywords: Antimicrobial susceptibility, amylase indicator, Aeromonas hydrophila Journal of Biomedical Investigation Vol. 4 (2) 2006 pp. 49-5

Locally prepared antibiotic sensitivity discs: a substitute for imported commercial discs

No Abstract. Global Journal of Pure and Applied Sciences Vol. 11(4) 2005: 461-46

Profiles of antibiotic susceptibilities of bacterial isolates and physico-chemical quality of water supply in rural Venda communities, South Africa

The Venda region of South Africa is predominantly rural and residents rely on untreated water sources for daily water needs. The physico-chemical quality of these water sources including antibiotic susceptibilities of enteric bacterial isolates which would guide clinicians in the empiric management of diarrhoea have received cursory attention. This study therefore sought to document the physico-chemical parameters and antibiograms of bacterial isolates from water sources in order to determine the safety for human consumption and to provide updated antibiotic data for empiric treatment of patients. Water samples were obtained on a weekly basis from Ngwedi, Mutale, Tshinane, Mutshindudi and Mudaswali Rivers and Makonde, Mudaswali and Thamathama Fountains between August 2000 and July 2002. Physico-chemical parameters such as turbidity, temperature, pH, lead, fluoride, cyanide, iron, sulphate, chromate and nitrate were determined. Antibiograms of bacterial isolates were ascertained using the disk diffusion method. Results obtained revealed that all the physico-chemical variables of the water sources analysed were within normal recommended limits for safety of drinking water except for turbidity, which exceeded recommended limits and hence precludes the rivers from direct domestic use. Antibiogram profiles showed multiple antibiotic resistances of Salmonella, Shigella, Campylobacter, Aeromonas, Vibrio cholera, Enterobacter and Plesiomonas to ampicillin, tetracycline, chloramphenicol, cotrimoxazole and erythromycin. In contrast virtually all the enteric bacterial isolates showed marked susceptibilities to ciprofloxacin, nalidixic acid, gentamicin, ceftriazone and amikacin. These effective antibiotics are therefore indicated in the empiric treatment of diarrhoeal cases or water-borne diseases of bacterial aetiology. Keywords: Water quality, Microbial, Physico-chemical, Antibiograms, Enteric bacteria, Rural communities, Venda region WaterSA Vol.30(4) 2004: 515-51

Gene encoding virulence markers among Escherichia coli isolates from diarrhoeic stool samples and river sources in rural Venda communities of South Africa

River water sources and diarrhoeic stools of residents in the Venda Region, Limpopo Province of South Africa were analysed for the prevalence of Escherichia coli (E. coli) and the presence of virulence genes among the isolates. A control group of 100 nondiarrhoeic stool samples was included. Escherichia coli was isolated and identified by standard cultural and biochemical methods. Pathogenicity of environmental and human isolates was determined by amplification of genes associated with virulence of E. coli, using specific primers. Of a total of 228 water and river sediment samples screened, E. coli was recovered from 200 (87.7%), and 135 (67.5%) of these had one or more genes associated with pathogenicity. The highest frequency of isolation of pathogenic strains was found in Ritavi River water and sediment (80.6%), followed by Lotanyanda River (76.9%), and the least (45.8%) in Nzhelele River 2. Escherichia coli was recovered from all of the 252 diarrhoeic stools tested (100%), and 119 (47.28%) of these had one or more genes associated with pathogenicity. The frequency of isolation of potential pathogenic E. coli from humans was highly significant (t = 6.3; pdย•0.01) in comparison to water isolates. Cytotoxic necrotizing Factor 1 (cnf1) and cytotoxic necrotising Factor 2 (cnf2) coding for necrotoxigenic E. coli (NEC); bundle-forming pilus (bfpA) and enteropathogenic attachment and effacement (eaeA) coding for enteropathogenic E. coli (EPEC), occurred in 35% and 34% respectively of river isolates. Heat-stable (ST) and heat-labile (LT) toxin genes coding for enterotoxigenic (ETEC) and Shiga-like toxin 1 (Stx1) and Shiga-like toxin 2 (Stx2) coding for Shiga-like toxin-producing E. coli (STEC) were not encountered in the river isolates. Isolates from stool samples had 21.8% and 12.6% of EPEC and NEC strains respectively; while enterotoxigenic (ETEC), Shiga-like toxin-producing (STEC) and enteroaggregative E. coli (EAEC) had a prevalence of 5%, 5.8% and 5.8% respectively. One human isolate possessed stx2 and eaeA indicating E. coliO157: H7. No genes associated with pathogenicity were observed in human non-diarrhoeic stool isolates. Results have revealed a possibility of a recycling of pathogenic E. coli strains, particularly the EPEC and NEC strains, between the water sources and the local population. Water SA Vol.30(1): 37-4