Evidence for chromosomal determination of fungicidal activity in strains of Lactobacillus brevis and Lactobacillus fermentum isolated from fermented foods.

The genetic basis of the fungicidal activity of strains of Lactobacillus brevis and L. fermentum isolated from indigenous fermented foods was determined. A 5.5-kb plasmid was isolated from L. brevis while L. Fermentum was found to harbor no plasmid. Plasmid curing indicated no correlation between the plasmid and the fungicidal activity of the Lactobacillus species. The fungicidal activity of the isolated organisms can be supposed to be mediated by the chromosome. No antibiotic resistance genetic markers were detected on the plasmid and hence it was classified as cryptic.

HIV association with conventional STDS (sexual transmitted diseases) in Lagos State, Nigeria.

The study examined a possible association between HIV infection and conventional sexually transmitted diseases (STDS) in a population of 700 patients seen in some hospitals and clinics in Lagos State between November 1997 and December 1999. The patients were drawn mainly from LUTH and Jolad hospitals in Lagos State. In these hospitals, patients who presented with symptoms of STDS were screened clinically and microbiologically for agents of STDS and HIV antibodies. Screening was carried out using conventional methods. A total of 150 (21.5%) were found positive for various STDS while 550 (78.5%) were negative Also, 109 (15.8%) were sero-positive for HIV while 591 (84.4%) were sero-negative. The frequency of STDS diagnosed were, Treponema pallidum, 38(25.3%), Neisseria gonorrhoea 3(2.0%), Chlamydia trachomatis 26(17.3), Hepatitis B virus 60(40.0%) Staphylococcus aureaus, 20 (13.3%) and Candida albicans 3(2.0%). Data showed that Syphillis was the most prevalent STDS diagnosed while Calbicans and N. gonorrhoea are the least. Amongst the 150 (21.5%) patients positive with STDS, 82(54.65%) were found to be positive for HIV antibodies. The remaining 68(45.3%) patients were negative for HIV. The difference in sero-prevalence on the true group of patients rates was significant. The higher rate in the STDS patients strongly suggest some association between HIV infections andSTDS amongst the patients studied p = 0.05. It was also recorded that HIV-1 infection is four times more prevalent than HIV-2 in these patients.

Genotyping of clinical and chicken isolates of Campylobacter jejuni and Campylobacter coli.

Genomic DNA from 58 strains of Campylobacter made up of 48 Campylobacter jejuni and ten Campylobacter coli were digested with Sma I and analysed by pulsed-field gel electrophoresis (PFGE). The cleavage of DNA by Sma I gave 22 distinct hybridization patterns. The two Campylobacter species were subtyped by PFGE. The average genomic size for C. jejuni by Sma I digestion was 1.73 Mb, while that of C. coli gave 1.7 Mb. Results from this study indicate that PFGE analysis by Sma I digested genomic DNA provides a reliable means of differentiating between and within species of Campylobacter and provides a practical approach to epidemiological studies of Campylobacter.

Prevalence of multi-drug resistant Salmonella typhi among clinically diagnosed typhoid fever patients in Lagos, Nigeria.

A total of 635 clinically diagnosed typhoid fever patients were bled from three different health institutions in the metropolis of Lagos, Nigeria over a period of 15 months, May 1997 to July 1998. Out of the total blood cultured, 101 (15.9%) isolates of Salmonella species were isolated of which 68 (67.3%) were S. typhi, 17 (16.8%) and 16 (15.8%) were S. paratyphi A. and S. arizonae respectively. The overall isolation rate of S. typhi among patients is 10.7%, with most isolates 45.9% found among the severely-ill young adults, age group 16-30 years. All isolates were subjected to anti-microbial susceptibility testing using 12 different antibiotics: chloramphenicol, ampicillin, cotrimoxazole, gentamicin, colistin sulfate, nalidixic acid, nitrofurantoin, cefotaxime, tetracycline, streptomycin, ofloxacin and ciprofloxacin. All the S. typhi and S. paratyphi A isolates showed resistance to two or more of the 10 of 12 antibiotics tested particularly the 3-first-line antibiotics commonly used (chloramphenicol, ampicillin and cotrimoxazole) in the treatment of typhoid fever in Nigeria. No isolate showed resistance to ofloxacin and ciprofloxacin, however, nalidixic acid and gentamicin showed a moderate and appreciable inhibition to most of our isolates.

Deoxyribonucleic acid restriction digest patterns in Campylobacter species: a comparison with Penner serotype.

Diversity, based on restriction fragment length polymorphism (RFLP) analysis, was studied in 48 strains of Campylobacter, comprising 27 chicken and 21 human strains of C. jejuni and C. coli, using genomic Southern hybridisation. Restriction digests of chromosomal DNA were prepared by treating with HaeIII and probed using a C. jejuni DNA probe. Nineteen distinct hybridisation patterns were identified, and differences in hybridisation pattern between members of the two species, and in individual strains of the same species, were seen. The method described proved more discriminatory than the Penner serotype, as strains from the same serotype were distinguished. The relative simplicity of the patterns obtained, together with the apparent diversity identified among individual strains and species, suggests that DNA fingerprinting using the C. jejuni DNA probe could be a useful identification method in epidemiological studies of Campylobacter infection in Nigeria.

PCR-based identification of Bacillus thuringiensis isolated from soil samples in Nigeria.

Six isolates of Bacillus thuringiensis isolated from soil samples confirmed to be toxic to mosquito larvae were differentiated using a PCR-Based technique. Three of these isolates initially identified using a serological technique were further differentiated with the PCR amplification of the delta-endotoxin target sequences. Using the total DNA of isolates as template, at least four isolates yielded amplicons one or all the crystal protein genes, cryI a, b, c, or II with sizes ranging from 238-1070 bp. None of these isolates yielded an amplicon for any of Cry IV A, B and D tested. Of the four isolates identified by PCR technique one isolate remained unidentified by serology.

Flagellin gene polymorphism analysis of Campylobacter compared with antigen serotyping.

Flagellin gene sequence polymorphisms were used to discriminate amongst 53 strains of Campylobacter jejuni and C. coli. The Campylobacter strains were made up of forty-three strains of Campylobacter jejuni and 10 strains of Campylobacter coli. The results were analysed in relation to Penner serotyping. Twenty DNA PCR-RFLP patterns (genotypes) were identified by analysis of Dde I fragment length polymorphisms in flagellin gene (fla A and fla B) polymerase chain reaction (PCR) products. Flagellin gene 13 genotype was a feature of 15% of strains, followed by flagellin gene 8 (9%). Differences in fragment patterns were observed not only between members of two species, but also between individual strains of the same species. The strains that were non-typable by the Penner serotype were distributed into 6 flagellin gene types. In conclusion, Ddc I fla typing is reproducible and offers high typability. However, when the scheme is used in combination with the Penner serotype it provides improved discrimination for the characterizing and subtyping of isolates.

Ribosomal RNA gene restriction fragment diversity amongst Penner serotypes of Campylobacter jejuni and Campylobacter coli.

Diversity based on ribosomal RNA gene-restriction endonuclease digest patterns was detected amongst forty-seven strains of Campylobacter made up of 38 strains of Campylobacter jejuni and 9 strains of Campylobacter coli. Restriction digests of chromosomal DNA prepared by treating with Hae III were probed with an oligonucleotide specific for Campylobacter 16S ribosomal RNA genes. Seventeen distinct hybridization patterns, each indicating the presence of 2-4 copies of the 16S rRNA gene are encoded in Campylobacter DNA. Differences in fragment patterns were observed not only between members of two species, but also between individual strains of the same species. Ribopattern fragments of 8.71, 7.56, 2.81 and 1.0 kb were characteristic of the majority of C. jejuni, whereas 7.59 and 4.68 kb fragments were commonly present in C. coli. In conclusion, Hae III ribotyping was even more discriminatory than the Penner serotyping of C. jejuni and C. coli, as strains of the same serotype were distinguished.

Comparison of survival of diarrhoeagenic agents in two local weaning foods (ogi and koko).

The pH values of both cooked and uncooked ogi and koko samples were determined and the survival rate of four diarrhoeagenic agents, enteroinvasive Escherichia coli, Salmonella typhi, Shigella flexneri, and Vibrio cholerae were studied after they were seeded into cooked ogi and koko. Analysis of the pH of the cooked inoculated samples showed that there was a slight increase in pH (decrease in acidity) during storage for 48 h and 37 degrees C (from 3.5 to 3.7 for ogi and from 3.7 to 4.1 for koko). The study also showed that ogi had a slightly lower pH value than koko both before and after cooking. In both cases, the cooked samples had a slightly lower pH value than the uncooked samples. The pH value of ogi ranged from 3.0 to 3.6 and that of koko from 3.5 to 3.9. The survival experiment showed that the inoculated enteric pathogens were inhibited in cooked ogi and koko during storage for 24-48 h. The antibacterial effect of cooked koko was more pronounced, on the four enteric pathogens studied, than that of cooked ogi. Except for Shigella flexneri and E. coli in ogi, non of the other bacteria studied was recovered after 24 h.

Biotyping of Campylobacter strains isolated in Lagos, Nigeria using the modified Preston biotype.

Fifty-eight Compylobacter strains were isolated from children with diarrhoea at various health centres in Lagos and from healthy chicken. Twenty-nine strains of Campylobacter were isolated from humans, while the same number were isolated from chicken. The strains were biotyped using the modified Preston biotype scheme. The Preston biotyping results have been compared with the results of Penner serotyping. Out of fifty-eight strains studied, the technique identified ten strains (17%) as C. coli, three (5%) as C. lari and fourty-five (78%) as C. jejuni, by the coding system. This technique identified twenty-eight Campylobacter species. This method highlights the usefulness of this technique in the biotyping of local strains, however, when the two schemes are used in combination they give excellent typing results suitable for epidemiological purposes.

Assessment of a bacteriocin-producing Lactobacillus strain in the control of spoilage of a cereal-based African fermented food.

As a part of a program to develop starter cultures aiding in the spoilage control and sanitation of African fermented foods, a cereal-based food ('ogi' and its solid form 'agidi' or 'eko') was prepared using a bacteriocin-producing Lactobacillus strain as the starter culture. The survival of an enterotoxigenic Escherichia coli strain was investigated in the naturally fermented food and in food fermented with the starter bacteriocin-producing Lactobacillus strain. An inhibition of E. coli was observed within 2 h of incubation in 'ogi' fermented with the bacteriocin producing strain. After 6 h, the viable count of E. coli in locally fermented 'ogi' was log 6.41 (2.54 X 10(6) CFU/mL), whereas in 'ogi' fermented with the bacteriocin producer it was reduced to log 1.70 (0.5 x 10(2) CFU/mL). Comparison of the shelf life of 'agidi' prepared from the naturally fermented food with that bacteriocin-producing starter culture showed that the latter had a better shelf life (kept for 11 d before spoilage occurred as compared with 7 d for the natural one). The results are discussed in terms of the potential of bacteriocin-producing cultures in the control and retardation of spoilage and food-forne infections in some African fermented foods.

Isolation and characterization of heavy metals resistant bacteria from Lagos Lagoon.

A total of 228 bacteria with an ability to resist toxic heavy metals were isolated from 8 selected sites of the Lagos Lagoon. The bacteria isolated were Staphylococcus sp., Bacillus sp., Pseudomonas sp., Streptococcus sp., Moraxella sp., Escherichia coli, Proteus sp., Klebsiella sp. and Salmonella sp. The heavy metals to which resistance was recorded were mercury, lead, zinc, cobalt, copper and chromium. The lagoon sites from which the highest number of resistant bacteria were isolated were Marina and Ebute-Ero. The heavy metal to which most bacteria were resistant was cobalt, while the least was chromium. The significance of the result is discussed in relation to the Nigerian environment and human health.

Diagnosis of sickle-cell disease by DNA analysis in Nigeria.

OBJECTIVE: To compare genotyping of leucocyte DNA by PCR and Dde I with the conventional genotyping of haemoglobin of the same subject. DESIGN: Comparative study. SUBJECTS: 25 adults, 16 males and nine females. MAIN OUTCOME MEASURES: Predictability. RESULTS: In all cases the results were comparable. CONCLUSIONS: The technology can be applied locally to prenatal diagnosis of sickle-cell disease by chorionic sampling and, therefore, improve the management of sickle-cell disease in Nigeria.

Antibiograms and plasmids of Staphylococcus aureus and coagulase negative staphylococci isolated from different clinical sources.

OBJECTIVES: To ascertain the antibiotic resistance patterns and plasmids of Staphyl coccus aureus and coagulae negative staphylococci isolated from different clinical specimens in Lagos, Nigeria. DESIGN: Prospective study involving the screening of specimens of blood, urine, skin and soft tissue infections, vagina, urethra, eye, ear, nose, pleural fluid and seminal fluid obtained from patients attending the Lagos University Teaching Hospital (LUTH) and Providence Hospital Diagnostic Laboratories, Lagos, Nigeria. SETTING: A laboratory based study conducted in the Microbiology Unit, University of Lagos and the National Institute for Medical Research (NIMR) Lagos, Nigeria. The patients were from different communities in Lagos. SUBJECTS: A total of 200 patients that were positive for the presence of S. aureus and coagulase negative staphylococci (CONS) were employed in the study. MAIN OUTCOME MEASURES: Frequency of isolation of S. aureus and coagulase negative staphylococci (CONS) from the different clinical specimens determination of their resistance profile using standard techniques for the isolation of both organisms and the Kirby-Bauer disc diffusion method for antibiotic testing. RESULTS: All the S. aureus and CONS isolates were sensitive to novobiocin and ofloxacin. Ninety eight (80 pc) of S. aureus isolates were resistant to tetracycline (Tet), 73 (60 pc) to Streptomycin (Str), and 49 (40 pc) to Chloramphenicol (Chl). All the S. aureus isolates were resistant to Penicillin (P) and only two (2 pc) and four (three pc) were resistant to Cefuroxime (Cxm) and Ceftriasone (Cro) in that order. Twenty six (21 pc) of S. aureus isolates were resistant to Methicillin. For CONS, 92 pc were resistant to Penicillin, 47 (60 pc) to streptomycin and 40 (51 pc) to tetracycline. Nineteen (24 pc) were resistant to Methicillin. Further antibiotic sensitivity results revealed the following patterns: 87 (71 pc) and 29 (36 pc) of S. aureus and CONS respectively showed P RTet"R, pattern of resistance. The resistance pattern PREryRGmRCazRCxmR was shown by only one (17 pc) of S. aureus and none (Opc) of CONS. Only 59% and four pc of S. aureus and CONS isolates showed resistance pattern ChlREryR, CazR respectively. Results of plasmid profiles showed that 48 (96 pc) of 50 S. aureus and 26 (87 pc) of 30 CONS isolates harboured one or more plasmids of molecular sizes ranging from 1.0 Kb to 19.5 Kb. Nine (19 pc) of 48 S. aureus and three (12 pc) of CONS isolates showed plasmid identity. CONCLUSION: We assert that although isolates of S. aureus and CONS showed multiple antibiotic resistance which could be plasmid mediated, only about five pc of both organisms showed resistance pattern ChlREryRCazRTetRCxmRSxtRGmR and EryRGmRCazRCxmR and this is of chemotherapeutic importance. Both organisms, were highly sensitive to Ceftriazone, Ceforoxime and Gentamicin. The high levels of resistance of many antibiotics may be attributable to indiscriminate use or antibiotic abuse in the community.

Prevalence, antimicrobial properties and beta-lactamase production of haemolytic enterobacteria in patients with diarrhoea and urinary tract infections in Legos, Nigeria.

OBJECTIVE: To determine the prevalence, antimicrobial properties and beta-lactamase production of haemolytic enterobacteria in patients with diarrhoea and urinary tract infections in Lagos, Nigeria. DESIGN: Hospital based prospective study. SUBJECTS: Total of 324 patients comprising 194 diarrhoeal and 130 urinary tract infection (UTI) cases. MAIN OUTCOME MEASURES: Production of haemolysms. beta-lactamase and antibiograms of isolates. RESULTS: 186 (57.41 pc) of the 324 clinical specimens screened were positive for enterobacteria, out of which 29 (15.59 pc) were haemolytic. Proteus vulgaris (2.78 pc) Klebsiella spp. (1.85pc). Escherichia coli (1.23 pc). Pseudomonas spp. (0.93 pc). Yersinia enterocolitics and Morganella morganii (0.62 pc). Salmonella spp. Vibrio cholerae and Proteus mirabilis (0.31pc) were the haemolytic enterobacteria Isolated. The susceptibilities of haemolytic bacteria to eight antibotics determined by disc-agar diffusion technique revealed that all 29 (100 pc) haemolytic isolates were sensitive to gentamycin and streptomycin but showed varied susceptibilities to the other drugs. Eleven (37.9 pc) of the 29 isolates produced beta-lactamase. CONCLUSION: We conclude that gentamycin and streptomycin are effective drugs against haemolytic isolates from diarrhoea and UTI cases.

Plasmid profiles and antimicrobial susceptibility patterns of Vibrio cholerae O1 strain isolated during a recent outbreak in Nigeria.

In a study on the outbreak of cholera in Nigeria in 1992, 86 strains of Vibrio cholerae O1 (79 Ogawa serotype and 7 Inaba serotype) were isolated. Antimicrobial susceptibility testing and plasmid profile analysis of the strains were done. Most isolates were highly sensitive to ciprofloxacin, cefotaxime, chloramphenicol, gentamicin, erythromycin, nalidixic acid, and nitrofurantoin, and less sensitive to ampicillin, penicillin, cloxacillin, cotrimoxazole, streptomycin, and tetracycline. The strains showed 13 resistant patterns; the commonest resistant patterns were Apr, Smr, and ApTcr. A total of 41 (47.6%) strains contained one or more plasmid(s) with sizes ranging from 4.5 kilobase to 150 kilobase. Ten isolates were able to transfer resistant plasmids to Escherichia coli K-12 by conjugation. Antibiogram patterns distinguished more isolates than in plasmid profile analysis. Plasmids specifying resistance to ampicillin, tetracycline, and trimethoprim were found. The differing patterns of antibiogram and plasmid profiles indicated that many circulating strains were responsible for the last outbreak in the country.

Vibriocidal activities of some local herbs.

Four of the seven tested medicinal plants exhibited antimicrobial activity against Vibrio cholerae. These 7 plants are: Ficus capensis, Mitragyna stipulosa, Entada africana, Piliostigma reticulatum, Terminalia avicennoides, Mimosa pudica, and Lannea acida. Of them Terminalia avicennoides showed higher antimocrobial activity than others. Potentials of these herbs in the control of cholera need to be determined.

Plasmid profiles and antibiotic susceptibility patterns of Staphylococcus aureus isolates from Nigeria.

In an investigation into the problems of infections due to Staphylococcus aureus in Nigeria, 100 strains were isolated from various hospitals in Lagos. The strains were screened for the presence of plasmids and for susceptibility to antimicrobial agents. Plasmids were extracted by modification of the method of Takahashi and Nagono[1]. The plasmids were diverse in nature. The strains were found to be highly resistant to commonly prescribed antibiotics.

Genetic analysis of tetracycline-resistant plasmids in enteropathogenic Escherichia coli isolated from patients in Nigeria.

Genetic analysis of antibiotic-resistant plasmids from 102 serologically defined strains of enteropathogenic Escherichia coli from Nigeria was carried out. All the isolates were screened for susceptibility to antibiotics, and 47 were found resistant to tetracycline. A total of 138 plasmids was isolated by agarose gel electrophoresis. Transformation and conjugation experiments showed that 57.4% of the resistant strains carried R-plasmids ranging in sizes from 2 to 46 x 10(6) daltons. Plasmid-determined resistance to tetracycline, ampicillin and streptomycin was found. Restriction endonuclease analysis of three of the commonest plasmids: p1679, p529 and p1479 revealed relatedness with respect to function and structure. The DNA segment on which TcR gene is located on each of them was identified by cloning into the vector plasmid pGL101. The recombinant plasmids pOADI and pOAD2 gave full expression of TcR gene when transformed into E. coli DHI. Furthermore, the tetracycline-resistant strains were examined for their phenotypic behaviour with respect to tetracycline and its lipophilic analogs.