Genetics of bi-component leukocidin and drug resistance in nasal and clinical Staphylococcus aureus in Lagos, Nigeria.

BACKGROUND: Resistant and virulent Staphylococcus aureus is a global public health challenge. Staphylococcal Bi-component leukotoxins are cytolytic to immune cells and evolve to disarm the innate immunity during infections, hence the severity of the disease. OBJECTIVE: We studied drug resistance profile and the occurrence of bi-component leukocidin in clinical and nasal S. aureus in Lagos, Nigeria. METHOD: Ninety-two S. aureus (70 clinical and 22 nasal) strains were characterized by conventional and molecular methods. RESULT: Of the resistance profiles generated, no isolate was resistant to fosfomycin, fusidic acid, teicoplanin, vancomycin, linezolid, mupirocin, nitrofurantoin and tigecycline. Twelve MRSA carrying staphylococcal cassette chromosome mecA gene types I, III, and IV elements were identified only in the clinical samples and type I dominated. High rates of lukE/D (100% among MRSA) and lukPV (dominated MSSA) were recorded among the nasal and clinical isolates. Staphylococcus aureus harboring only lukE/D (from clinical & colonizing MSSA) and combined lukE/D and lukPV (mostly from clinical MSSA, colonizing MSSA and clinical MRSA) toxins were found. CONCLUSION: Although, mecA resistant genes were found only among clinical MRSA, the occurrence of other bi-component leukocidin genes in a large proportion among the isolates from both community and clinical settings is a major concern. The need for effective resistance and virulence factor surveillance, re-enforcement of antibiotic stewardship and good infection control policy, to prevent dissemination of epidemic strains is highlighted.

Genetic variation among Clostridium perfringens isolated from food and faecal specimens in Lagos.

BACKGROUND: Clostridium perfringens is an anaerobic Gram-positive bacterium which is commonly present in the gastrointestinal tract of man and animals and causes enteritic diseases in animals and food poisoning in humans. Previous studies have looked at the epidemiological relationship between C. perfringens isolates from outbreak source. In this study, the genetic diversity of C. perfringens strains from non-outbreak food and faecal specimens was investigated for epidemiological purposes. METHODS: We analyzed thirty-eight (38) Clostridium perfringens strains isolated from food and faecal specimens in Lagos State. Bacterial identification was done using colonial morphology, Gram stain reaction, conventional biochemical tests and PCR. Genetic analysis was performed using arbitrary primed polymerase chain reaction (AP-PCR) technique with oligonucleotide primer of random sequences (OPA-3) to determine the genetic diversity of C. perfringens. The distance between the different bands produced were analyzed using numerical taxonomy and multivariate system software (NTSYS). RESULTS: Seventeen (44.7%) C. perfringens strains showed at least one polymorphic DNA patterns when genotyped. However, this method identified polymorphisms among the C. perfringens species from which four genetic groups (1, 2, 3 and 4) were established. CONCLUSIONS: Our findings suggest that there may be faecal contamination of food products and similar clones of Clostridium perfringens may be incriminated.

CARRIAGE OF MULTIDRUG RESISTANT ENTEROCOCCUS FAECIUM AND ENTEROCOCCUS FAECALIS AMONG APPARENTLY HEALTHY HUMANS.

BACKGROUND: Enterococci are indigenous flora of the gastro-intestinal tracts of animals and humans. Recently, interest in two major species, E. faecium and E. faecalis, has heightened because of their ability to cause serious infections and their intrinsic resistance to antimicrobials. This study was aimed at determining the prevalence of E. faecium and E. faecalis in human faecal samples and evaluating the susceptibility of the isolates to antibiotics. MATERIALS AND METHODS: One hundred faecal samples were collected from apparently healthy individuals and analysed using conventionalbacteriological methods. The susceptibility profile of the isolates to nine antibiotics were determined using disk diffusion method. RESULTS: Seventy-three (73) Enterococcus were phenotypically identified and 65 of the isolates were differentiated into 36 (55.4%) E. faecium and 29 (44.6%) E. faecalis. Eight (8) isolates could not be identified by the conventional biochemical methods employed. No dual colonization by the E. faecalis and E. faecium was observed and isolation rate was not dependent on sex of the participants. All the isolates were resistant to ceftriaxone, cefuroxime and ceftizoxime. Enterococcus faecium exhibited resistance toerythromycin (88.9%), gentamicin (77.8%), amoxicillin-clavulanate (63.9%), ofloxacin (44.4%), teicoplanin (19.4%) and vancomycin (16.7%). Enterococcus faecalis showed the least resistance to vancomycin (13.8%) and teicoplanin (27.7%). Remarkable multiple antibiotic resistances to the classes of antibiotic tested were observed among the two species. CONCLUSION: The high carriage rate of antibiotic resistant E. faecium and E. faecalis in this study provides information on the local antibiotic patterns of our enterococci isolates thereby suggesting that they could present as important reservoir and vehicle for dissemination of resistant genes in our community.

Detection of toxigenic Clostridium perfringens and Clostridium botulinum from food sold in Lagos, Nigeria.

Food-borne diseases contribute to the huge burden of sickness and death globally and in the last decade, have become more frequently reported in Africa. In line with this, food safety is becoming a significant and growing public health problem in Nigeria. Diarrhoea is a common problem in Nigeria and has been reported but there has been little data on the possibility of clostridia as aetiological agents. Clostridium species are ubiquitous in the environment and in the gastrointestinal tract of man and animals and can serve as a marker for faecal contamination. We set out to determine the potential of these foods to transmit Clostridium species. A total of 220 food commodities from six local governments in Lagos State were sampled. Isolates obtained were identified based on cultural, morphological and biochemical characteristics. Toxinotyping was done using multiplex-PCR with primers specific for alpha, beta, epsilon and iota-toxin genes, enterotoxigenic cpe gene and neurotoxigenic BoNt gene. Fifty (22.7%) clostridial species were isolated of which 29 (58%) were identified as C. perfringens. Toxinotyping of the 29 strains showed that 28 (96.6%) were toxin producing C. perfringens type A while one (3.4%) was C. perfringens type D. Two (4%) C. botulinum species were isolated and identified by 16S rRNA sequencing, both harbouring BoNt/A gene. The contamination rates of food with Clostridium species show that food hygiene is a problem and Clostridium species may be a source of food borne disease in Lagos State, Nigeria.

Persistence of fluoroquinolone-resistant Salmonella enterica serovar Kentucky from poultry and poultry sources in Nigeria.

INTRODUCTION: This study investigated the antimicrobial resistance and clonality of Salmonella enterica serotype Kentucky in poultry and poultry sources in Nigeria, and compared the isolates with the clone of S. Kentucky STI98-X1 CIPR using (PFGE) and (MIC). METHODOLOGY: Fecal samples from chickens and poultry sources (litter, water, rodent and lizard fecal samples) were collected from  fourteen (14) poultry farms in 2007, 2010 and 2011 and were analyzed for S. Kentucky. RESULTS AND CONCLUSIONS: Six percent of the samples were positive for S. Kentucky - all resistant to nalidixic acid and ciprofloxacin. The isolates are grouped within the PFGE cluster X1 of S. Kentucky STI98 CIPR, indicating the association to the emerging and widely spread CIPR S. Kentucky clone with poultry and poultry sources.

The potential role of mobile phones in the spread of bacterial infections.

BACKGROUND: Mobile phones are indispensable accessories both professionally and socially but they are frequently used in environments of high bacteria presence. This study determined the potential role of mobile phones in the dissemination of diseases. METHODOLOGY: Specifically, 400 swab samples from mobile phones were collected and divided into groups categorized by the owners of the phones as follows: Group A was comprised of 100 food vendors; Group B, 104 lecturers/students; Group C, 106 public servants; and Group D, 90 health workers. Samples were cultured and the resulting isolates were identified and subjected to antimicrobial susceptibility tests by standard procedures. RESULTS: The results revealed a high percentage (62.0%) of bacterial contamination. Mobile phones in Group A had the highest rate of contamination (92; 37%), followed by Group B (76; 30.6%), Group C (42; 16.9%), and Group D (38; 15.3%). Coagulase negative Staphylococcus (CNS) was the most prevalent bacterial agent from mobile phones in Group A (50.1%) and least from phones in Group D (26.3), followed by S. aureus. Other bacterial agents identified were Enterococcus feacalis, Pseudomonas aeruginosa, Escherichia coli, and Klebsiella spp. There was no statistical significance difference (P < 0.05) in the occurrence of S. aureus, the most frequently identified pathogenic bacterial agent isolated from the mobile phones in the study groups. Fluoroquinolones and third-generation cephalosporin were found to be effective against most isolates. CONCLUSION: Mobile phones may serve as vehicles of transmission of both hospital and community-acquired bacterial diseases. Strict adherence to infection control, such as hand washing, is advocated.

Associated risk factors and pulsed field gel electrophoresis of nasal isolates of Staphylococcus aureus from medical students in a tertiary hospital in Lagos, Nigeria.

Staphylococcus aureus infections are growing problems worldwide with important implications in hospitals. The organism is normally present in the nasal vestibule of about 35% of apparently healthy individuals and its carriage varies between different ethnic and age groups. Staphylococcal nasal carriage among health workers is particularly important to establish new clones and track origin of infections during outbreak situations. To determine the carriage rate and compare the pulsed field gel patterns of the strains, nasal swabs were collected from 185 medical students in a teaching hospital in Lagos, Nigeria. Isolates of S. aureus were tested for heamolysin production, methicillin sensitivity and Pulsed Field Gel Electrophoresis (PFGE) was performed. The results showed S.aureus nasal carrier rate of 14% with significant rate among males compared to females. All the isolates produced heamolysin. Antibiotic susceptibility pattern revealed that majority of the isolates was susceptible. Five strains (19%) harboured resistant determinants to penicillin and tetracycline. None of the strains was resistant to methicillin. 44% of the isolates typed by PFGE had type B, the most predominant pulsotype. PFGE A clone exhibited a single resistance phenotype suggesting a strong clonal relationship that could punctual an outbreak in the hospital. The results speculate that nasal carriage among medical personnel could be a function of various risk factors. Personal hygiene and behaviour may however be the means to reducing colonization and spread of S.aureus in our hospitals.

Associated risk factors and pulsed field gel electrophoresis of nasal isolates of Staphylococcus aureus from medical students in a tertiary hospital in Lagos, Nigeria

Staphylococcus aureus infections are growing problems worldwide with important implications in hospitals. The organism is normally present in the nasal vestibule of about 35 percent of apparently healthy individuals and its carriage varies between different ethnic and age groups. Staphylococcal nasal carriage among health workers is particularly important to establish new clones and track origin of infections during outbreak situations. To determine the carriage rate and compare the pulsed field gel patterns of the strains, nasal swabs were collected from 185 medical students in a teaching hospital in Lagos, Nigeria. Isolates of S. aureus were tested for heamolysin production, methicillin sensitivity and Pulsed Field Gel Electrophoresis (PFGE) was performed. The results showed S.aureus nasal carrier rate of 14 percent with significant rate among males compared to females. All the isolates produced heamolysin. Antibiotic susceptibility pattern revealed that majority of the isolates was susceptible. Five strains (19 percent) harboured resistant determinants to penicillin and tetracycline. None of the strains was resistant to methicillin. 44 percent of the isolates typed by PFGE had type B, the most predominant pulsotype. PFGE A clone exhibited a single resistance phenotype suggesting a strong clonal relationship that could punctual an outbreak in the hospital. The results speculate that nasal carriage among medical personnel could be a function of various risk factors. Personal hygiene and behaviour may however be the means to reducing colonization and spread of S.aureus in our hospitals.

Salmonellosis in Lagos, Nigeria: incidence of Plasmodium falciparum-associated co-infection, patterns of antimicrobial resistance, and emergence of reduced susceptibility to fluoroquinolones.

The present study was undertaken to examine the status of antimicrobial resistance in Salmonella-associated diseases, by verifying possible emergence of reduced susceptibility to fluoroquinolones in Salmonella isolates and determining the incidence of Plasmodium falciparum-associated co-infection with Salmonella serotypes. Antimicrobial resistance in clinical isolates of Salmonellae was examined for a 12-month period. Four hundred and forty-one patients comprising two groups were recruited. Group A comprised 235 patients diagnosed by clinicians of having pyrexia, and group B included stool samples of 206 patients presenting with gastroenteritis. Samples were cultured and isolates identified, and drug susceptibility testing was performed using the standard methods. Of the 235 samples screened in group A, 42 Salmonella isolates and 107 Plasmodium spp. were identified. Of the 42 Salmonella isolates, 19 (45.2%) were Salmonella Typhi, 9 (21.4%) S. Enteritidis, and 7 (16.7%) each of S. Paratyphi and S. Arizonae. Plasmodium spp.-associated co-infection with Salmonellae was observed in 16 patients mostly in complicated typhoidal cases and S. Enteritidis-associated bacteraemia. Fifty-three of the 206 stool samples from group B patients were confirmed positive for bacterial pathogens, made up of 35 Salmonella and 18 Shigella isolates. Of the Salmonella isolates, 18 (51.4%) were S. Enteritidis, 11 (31.4%) S. Arizonae, 4 (11.4%) S. Paratyphi, and 2 (5.7%) S. Typhi. There was no statistically significant difference (p < 0.01) in antimicrobial resistance patterns exhibited among typhoidal Salmonellae isolated in 2000 and 2005. A similar trend in resistance was recorded for non-typhoidal Salmonellae (p < 0.05). For the first time in Lagos, Nigeria, Salmonella isolates (10-18%) with reduced susceptibility to both ciprofloxacin and ofloxacin at MIC50 and MIC90 values of 0.015 and 0.03 microg/mL respectively were found. Despite this development, ciprofloxacin and ofloxacin remain the drug of choice for severe cases of salmonellosis, although caution should be exercised by clinicians in their prescriptions such that fluoroquinolone antibiotic therapy is used only in laboratory-proven cases of typhoid fever and Salmonella-associated bacteraemia to preserve its efficacy.

Resistotyping of Campylobacter jejuni.

The principal objective of typing in epidemiology is to trace a strain as it passes from one individual to another. Resistotyping is a phenotypic method that consists of testing bacterial strains against a set of arbitrarily chosen chemical agents, whereby, a resistance pattern that is characteristic of a strain is generated and, is believed to describe the isolates for epidemiological purposes. This simple typing system is described for campylobacter isolated in Lagos, Nigeria. Resistotyping was performed with twenty chemical agents incorporated into disc. The resistotyping results revealed that the twenty isolates from human and chickens belonged to 14 different resistotypes with the largest group comprising 25% of the isolates. The human strains were distinctly differentiated into eight resistotypes. All the Campylobacter Jejuni isolates were resistant to potassium chloride (A), Boric acid (B), Sodium biselenite (C), potassium dischromate (F), potassium permanganate (I) ferrous sulphate (N), magnesium sulphate (O), sodium hydrogen phosphate (P), sodium sulphate (Q), and magnesium chloride (R). Only one strain was resistant to mercuric chloride (M) while three of the strains were sensitive to disodium orthophosphate (H), sodium azide (J), and metronidazole (T). The method seems to be adequate for defining the relatedness of our isolates in epidemiologic situation and has proven promising for Campylobacter jejuni in our environment.

Prevalence of Helicobacter pylori vacA, cagA and iceA genotypes in Nigerian patients with duodenal ulcer disease.

Distinct virulence factors of Helicobacter pylori have been associated with clinical outcome of the infection; however, considerable variations have been reported from different geographic regions. Data on genotypes of African H. pylori isolates are sparse. The aim of this study was to determine the prevalence of specific genotypes of H. pylori in Nigerian patients with duodenal ulcer and non-ulcer dyspepsia. H. pylori was cultured from endoscopic biopsies obtained from 41 Nigerian patients (19 with duodenal ulcer, 22 with non-ulcer dyspepsia). The vacA alleles, cagA and iceA genotypes were determined by PCR. The vacA s1,m1 and s1,m2 genotypes were found in 26.3% and 22.7%, and in 73.7% and 72.7% of H. pylori isolates from patients with duodenal ulcer and non-ulcer dyspepsia, respectively. The iceA1 genotype was present in 94.7% and 86.4% of isolates from duodenal ulcer and non-ulcer dyspepsia patients, respectively. cagA+ infection was found predominantly (> 90%) in Nigerian H. pylori isolates irrespective of the clinical diagnosis. In conclusion, vacA s1,m2, iceA1 and cagA+ are common genotypes of H. pylori isolated from Nigerian patients. As in several other developing countries there seems to be no association between these genotypes and duodenal ulcer disease.

Human campylobacteriosis in developing countries.

Campylobacteriosis is a collective description for infectious diseases caused by members of the bacterial genus Campylobacter. The only form of campylobacteriosis of major public health importance is Campylobacter enteritis due to C. jejuni and C. coli. Research and control efforts on the disease have been conducted more often in developed countries than developing countries. However, because of the increasing incidence, expanding spectrum of infections, potential of HIV-related deaths due to Campylobacter, and the availability of the complete genome sequence of C. jejuni NCTC 11168, interest in campylobacteriosis research and control in developing countries is growing. We present the distinguishing epidemiologic and clinical features of Campylobacter enteritis in developing countries relative to developed countries. National surveillance programs and international collaborations are needed to address the substantial gaps in the knowledge about the epidemiology of campylobacteriosis in developing countries.