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.

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.

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.

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.

Plasmid profiles of bacteriocin-producing Lactobacillus isolates from African fermented foods.

Fourteen of 200 Lactobacillus isolates from African fermented foods, viz. 'wara', 'kenkey', 'ugba', 'ogi', 'kunuzarki', 'fufu' and 'iru' were found to produce bacteriocins against L. plantarum and only three bacteriocinogenic isolates inhibited some of the food pathogens. Plasmid analysis of the 14 bacteriocin-producing lactobacilli showed that only 5 isolates harbored plasmids ranging in size from 3.1 to 55.5 kb.

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.

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.

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.

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.

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.

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.

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.

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.

Antibiotic susceptibility patterns and plasmid profile of Helicobacter isolates from Nigeria.

Antibiotic susceptibility testing and plasmid screening of 50 local isolates of Campylobacter coli and Campylobacter jejuni were done. All isolates were sensitive to ofloxacin but were resistant to ampicillin, cloxacillin, penicillin, streptomycin and aztreonam. A large number of isolates were sensitive to nalidixic acid (96%), ceftriaxone (96%) and chloramphenicol (86%). It is noteworthy that nine (18%) of the isolates were resistant to each of erythromycin, 15 (30%) were found to harbour plasmid DNA ranging in sizes from 2.0 to 45 megadalton. Resistance to tetracycline in one isolate was associated with the carriage of a 45-megadalton plasmid.

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.

Cloning and restriction mapping of the L-sorbose utilization genes from a clinical isolate of Escherichia coli (1).

About 30% of clinical isolates of Escherichia coli tested utilized L-sorbose as a carbon and energy source. Escherichia coli K-12 is naturally sorbose negative. The genes for L-sorbose utilization (sor+) is being used as a prototype for studying variable genes amongst bacterial pathogens. The sor+ genes from seven isolates were transferable to E. coli K-12. The (sor+) region was cloned into plasmid pBR322 to give pDOK1. Plasmid pDOK1 is approximately 20kb in size. A restriction endonuclease map of pDOK1 is presented.

Transduction of citrate-utilization genes into Escherichia coli K12.

Genes for citrate utilization were transferred by transduction into Escherichia coli from Salmonella and Klebsiella strains. The genes appear to take chromosomal positions at 6-10 min on the K12 linkage map. Growth on citrate medium by Cit+ K12 hybrids was poor. Incorporate of glycine or L-serine into citrate minimal media improved growth of K12 Cit+ hybrids on citrate. The significance of these findings is discussed.

Drug resistance and plasmids of Bacillus isolated from locally fermented foods.

In an epidemiological survey of antibiotic resistance in this environment, Bacillus bacteria were isolated from commonly consumed fermented foods. The fifty strains isolated were tested for susceptibility to antibiotics and screened for the presence of plasmids. Majority (72%) were resistant to Cloxacillin and Penicillin (70%) while 40% harbour plasmids ranging from 3.0kb-36.3kb in molecular weight. A 4.6kb plasmid was found to be common to all plasmid-bearing strains. The implication for the epidemiology of antibiotic resistance is discussed.

Cloning and characterization of the tetracycline resistance determinant from enteropathogenic Escherichia coli p1479.

As part of an epidemiological study, R plasmids coding for tetracycline resistance were isolated from enteropathogenic Escherichia coli. A 1.4kb Pst 1 fragment of one of them p1479 (size 5.7kb) has been cloned into plasmid pGL101. This recombinant plasmid containing the tetracycline gene was then transformed into E. coli DHI where the tetracycline resistant gene was fully expressed. Attempts to develop this clone to a diagnostic probe is now in progress.

The prevalence of ABO blood group antigens and antibodies in Lagos State, Nigeria.

A total of 1239 normal donors from the Lagos University Teaching Hospital (LUTH) and 111 staff of the National Institute for Medical Research (NIMR) Yaba were screened for ABO antibodies. Of the number from LUTH, 220 (17.8%) were found to be in group A, 282 (22.8%) in group B, 85 (6.9%) in group AB and 652 (52.6%) in group O. The number from NIMR consisted of 20 (18.0%) in group A, 25 (22.5%) in group B 8(7.2%) in group AB and 58 (52.3%) in group O. The mean tile avidity time of sera from 789 (62.66%) potent LUTH donors was less than 35 seconds. Only 97 (6.91%) of this reacted within 10 seconds. On the other hand, only 11(9.9%) of the NIMR sera reacted within 35 seconds and none reacted within 10 seconds. Group O individuals from LUTH and NIMR did not always have anti-A and anti-B components of their sera with equal avidity or potency. It was also observed that high avidity of antibody did not necessarily correspond with high potency. The commonest titre for group B (anti-A) sera was 256 and that for group A (anti-B) was 512. In general, anti-B titres tended to be consistently higher than anti-A. There was a bimodal peak at titres 32 and 256 in group B (anti-A) sera. This repeated itself in the anti-A component of group O sera (i.e., anti-A+B), but here the peaks occurred at 32 and 128.(ABSTRACT TRUNCATED AT 250 WORDS)