A study of the antimicrobial resistance and transfer of resistance among organisms isolated from lettuce (Lactuca sativa) leaves in three localities in southwest Nigeria.

The bacterial flora of lettuce from western Nigeria were investigated for their identity, antimicrobial resistance, and ability to transfer such resistance to other organisms. The isolated contaminants were mostly Gram-negative organisms of the Enterobacteriaceae family, which included Enterobacter species and E. coli. The organisms were resistant to a wide range of antimicrobials and they exhibited multiple antimicrobial resistance phenotypes. Common resistance phenotypes observed included those to beta lactam antibiotics, trimethoprim, and streptomycin. A majority of the isolates had minimum inhibitory concentration of trimethoprim over 1,000 mg/L and they were shown to possess the ability to transfer their resistance to a plasmidless E. coli strain. The results of the authors' study underscore the contributory role of lettuce in the dissemination of antimicrobial resistance in the Nigerian community.

Diversity of antibiotic resistance genes and staphylococcal cassette chromosome mec elements in faecal isolates of coagulase-negative staphylococci from Nigeria.

BACKGROUND: Coagulase-negative staphylococci (CoNS) are opportunistic pathogens found as colonisers of the human gut. This study was carried out to examine the genetic resistance mechanisms in faecal isolates of CoNS. The study investigated 53 non-duplicate CoNS isolates obtained from the fresh stool samples of apparently healthy subjects in the community of Ile-Ife, South-Western Nigeria. Antibiotic susceptibility testing was assessed by the disc diffusion test while antibiotic resistance genes were analysed by PCR. mecA positive isolates were analysed by Staphylococcal Chromosome Cassette mec (SCCmec) and cassette chromosome recombinase (ccr) complex typing methods. RESULTS: Resistance genes were detected only in isolates that showed resistance by phenotypic screening. The aac(6')-aph(2") gene was detected in all the three isolates resistant to gentamicin. Four of the five erythromycin resistant isolates were positive for the ermC gene, the remaining isolate carried the msrA gene. The tetK gene was detected in 6 of the 7 tetracycline resistant isolates while 4 possessed the tetM gene. Three of the isolates (S. haemolyticus, S. xylosus and S. capitis) had both genes. Several SCCmec types were found: SCCmec I- ccrABß2-α2 (4 isolates: 3 S. epidermidis, 1 S. warneri), SCCmecIVb- ccrABß2-α3 (1 isolate: S. epidermidis), SCCmecIVd- ccrABß2-α3 (8 isolates: 3 S. epidermidis, 2 S. xylosus, 1 S. saprophyticus, 1 S. warneri, 1 S. capitis), and untypable (2 isolates: S. epidermidis). CONCLUSION: This genetic background could be a reservoir for interspecies gene transfer among CoNS and S. aureus in the intestinal tract.

The pathogenicity of Staphylococcus epidermidis on the intestinal organs of rats and mice: an experimental investigation.

BACKGROUND: Staphylococcus epidermidis is the most frequently isolated species of the coagulase negative staphylococci from human stool. However, it is not clear how its presence in the gut affects the cellular structures and functions of this organ. In this study therefore, the pathogenicity of strains of S. epidermidis which were isolated from the stool samples of apparently healthy children was investigated in mice and rats. METHODS: The albino mice (22-30 g) and albino rats (100-155 g) of both sexes were infected orally and intraperitoneally with graded doses of the bacteria and subjected to behavioral and histopathological examinations. RESULTS: Acute infection in these animals caused temporary behavioural changes as shown by restlessness and abdominal stretchings but did not result in death even at a dosage of 2 × 109 cfu/kg. Daily administration of the same dose for 14 days resulted in the death of 11 out of 21 (52.4%) mice. Histopathological examination of the affected organs showed congestions, aggregations and multinucleated hepatocytes in the liver, infiltration of the kidney tubule interstitial by chronic inflammatory cells, coagulative necrosis of the kidney, spleen, intestine and stomach cells as well as marked stroma fibrosis of the spleen. Coagulative necrosis of cells was the most frequently occurring pathological alteration. Lethality and pathological effects reflected the virulence factors expressed by the organism which are biofilm formation, haemagglutination properties and capsule production. CONCLUSIONS: The results indicate that strains of S. epidermidis colonising the gut can cause serious pathological changes on certain organs such as kidney, liver, intestine, stomach and spleen which, depending on their severity, could be fatal.

Serogroup distribution of Shigella in Ile-Ife, southwest Nigeria.

BACKGROUND: Shigellosis is endemic throughout the world and Shigella spp. is among the most common pathogens responsible for bacterial diarrhoeal diseases. Death attributed to shigellosis is common in developing countries, where affected populations are immunologically compromised due to poor nutrition and background infections. AIM: To investigate the serogroup distribution of Shigella spp. recovered from clinically diagnosed cases of gastroenteritis and acute diarrhoea among children (0-5 years) in Ile-Ife, southwest Nigeria between September 2003 and September 2006. METHODS: The isolates were identified and characterized biochemically and serologically. RESULTS: Out of 102 Shigella isolates identified, 45 (44%) were S. flexneri, 26 (25%) were S. dysenteriae, 19 (19%) were S. boydii, 6 (6%) were S. sonnei and 6 (6%) were untypable strains. CONCLUSIONS: We conclude that Shigella serogroups can be considered an important aetiological agent of acute diarrhoea and mortality among children in Ile-Ife, southwest Nigeria.

Rapid evolution of fluoroquinolone-resistant Escherichia coli in Nigeria is temporally associated with fluoroquinolone use.

BACKGROUND: Antibiotic resistance has necessitated fluoroquinolone use but little is known about the selective forces and resistance trajectory in malaria-endemic settings, where selection from the antimalarial chloroquine for fluoroquinolone-resistant bacteria has been proposed. METHODS: Antimicrobial resistance was studied in fecal Escherichia coli isolates in a Nigerian community. Quinolone-resistance determining regions of gyrA and parC were sequenced in nalidixic acid resistant strains and horizontally-transmitted quinolone-resistance genes were sought by PCR. Antimicrobial prescription practices were compared with antimicrobial resistance rates over a period spanning three decades. RESULTS: Before 2005, quinolone resistance was limited to low-level nalixidic acid resistance in fewer than 4% of E. coli isolates. In 2005, the proportion of isolates demonstrating low-level quinolone resistance due to elevated efflux increased and high-level quinolone resistance and resistance to the fluoroquinolones appeared. Fluoroquinolone resistance was attributable to single nucleotide polymorphisms in quinolone target genes gyrA and/or parC. By 2009, 35 (34.5%) of isolates were quinolone non-susceptible with nine carrying gyrA and parC SNPs and six bearing identical qnrS1 alleles. The antimalarial chloroquine was heavily used throughout the entire period but E. coli with quinolone-specific resistance mechanisms were only detected in the final half decade, immediately following the introduction of the fluoroquinolone antibacterial ciprofloxacin. CONCLUSIONS: Fluoroquinolones, and not chloroquine, appear to be the selective force for fluoroquinolone-resistant fecal E. coli in this setting. Rapid evolution to resistance following fluoroquinolone introduction points the need to implement resistant containment strategies when new antibacterials are introduced into resource-poor settings with high infectious disease burdens.

Antimicrobial resistance in Escherichia coli strains from urinary tract infections.

BACKGROUND: An increase in resistance against many different drugs among urinary tract infection (UTI) E coli isolates has been observed in the last 2 decades. This study determined the trends of antimicrobial resistance in E coli to commonly used antibiotics. METHODS: The study was conducted in Ile-Ife, southwest Nigeria. Patients with features suggestive of UTI were investigated for presence of significant bacteriuria. Urine isolates were identified. Antimicrobial susceptibility was evaluated in accordance with standard bacteriological methods. RESULTS: Of 442 urine specimens, 158 (35.8%) yielded significant growth, including 41 (25.6%) with E coli. Among the E coil isolates, antimicrobial susceptibility varied in prevalence by agent in descending order as follows: nitrofurantoin (80%), ofloxacin (24%), ciprofloxacin (15%), nalidixic acid (10%), cotrimoxazole (5%), and amoxicillin/clavulanic acid (2%). No isolate was susceptible to amoxicillin, gentamicin, or tetracycline. All were also found to be resistant to at least 3 commonly used drugs. All 25 isolates tested for extended-spectrum beta-lactamase (ESBC) production were found to be presumptive ESBCs producers. CONCLUSION: The results demonstrate the continued susceptibility of E coil to nitrofurantoin and their widespread and increasing resistance to amoxicillin, gentamicin, cotrimoxazole, ciprofloxacin, ofloxacin, and tetracycline. Nitrofurantoin is a--and, in this locale, perhaps the only--rational drug for empiric treatment of uncomplicated UTI. There is a need for a comprehensive study of the involvement of ESBC-producing E coli in UTI in this environment.

Correction: Classes 1 and 2 integrons in faecal Escherichia coli strains isolated from mother-child pairs in Nigeria.

[This corrects the article DOI: 10.1371/journal.pone.0183383.].

The response of students to malaria and malaria therapy in a university in southwest Nigeria.

BACKGROUND: Malaria is both a social and a behavioral problem that may prompt individuals' demonstration of culturally prescribed behavioral patterns, which in turn, may contribute to their perception and treatment of the disease. OBJECTIVES: The study examines the problems associated with the ways in which students of a Nigerian university perceive malarial infection, seek treatment for the infection, and respond to available treatment options. METHODS: Data were collected using a questionnaire that was administered to 600 male and female undergraduate students in final year classes in 6 fields of study at Obafemi Awolowo University, Ile Ife: technology, environmental sciences, social sciences, humanities, health sciences, and pharmacy. An interview schedule was used to conduct an in-depth interview with 120 students who were selected using a systematic sampling technique. The research instrument was pilot tested for validity and reliability, and the items of data obtained were analyzed using descriptive and inferential statistics. RESULTS: Results revealed that student respondents suffered an average of 2.33 malaria attacks per annum, with male students suffering a significantly greater number of attacks than the females (chi(2)=17.21, df=3, P=.05). Additionally, it was observed that 48% of females admitted a preference for injections over other dosage forms compared to 33.3% of their male counterparts. Injections were favored by females because of rapid onset of action and bitter taste accompanying oral dosage forms. It is worth noting, however, that even within this group, self-medication was quite prominent, suggesting that injections are used without the benefit of medical supervision in the sample population. Although no less than 54.6% of the respondents claimed to suffer from chloroquine-induced pruritus, 41% of the respondents used chloroquine preparations as their drug of choice in seeking a cure for their malarial infection, whereas only 4% used it for prevention of the diseases. CONCLUSION: This study showed that there is no noticeable difference in the perception of malaria between male and female students; however, there is a significant difference between the frequency of attacks in the 2 groups, and this may have considerable influence on the ways male and female subjects treat the infection and their subsequent response to treatment.

Classes 1 and 2 integrons in faecal Escherichia coli strains isolated from mother-child pairs in Nigeria.

BACKGROUND: Antimicrobial resistance among enteric bacteria in Africa is increasingly mediated by integrons on horizontally acquired genetic elements. There have been recent reports of such elements in invasive pathogens across Africa, but very little is known about the faecal reservoir of integron-borne genes. METHODS AND FINDINGS: We screened 1098 faecal Escherichia coli isolates from 134 mother-child pairs for integron cassettes by PCR using primers that anneal to the 5' and 3' conserved ends of the cassette regions and for plasmid replicons. Genetic relatedness of isolates was determined by flagellin and multi-locus sequence typing. Integron cassettes were amplified in 410 (37.5%) isolates and were significantly associated with resistance to trimethoprim and multiple resistance. Ten cassette combinations were found in class 1 and two in class 2 integrons. The most common class 1 cassette configurations were single aadA1 (23.4%), dfrA7 (18.3%) and dfrA5 (14.4%). Class 2 cassette configurations were all either dfrA1-satI-aadA1 (n = 31, 7.6%) or dfrA1-satI (n = 13, 3.2%). A dfr cassette was detected in 294 (31.1%) of trimethoprim resistant strains and an aadA cassette in 242 (23%) of streptomycin resistant strains. Strains bearing integrons carried a wide range of plasmid replicons of which FIB/Y (n = 169; 41.2%) was the most frequently detected. Nine isolates from five different individuals carried the dfrA17-aadA5-bearing ST69 clonal group A (CGA). The same integron cassette combination was identified from multiple distinct isolates within the same host and between four mother-child pairs. CONCLUSIONS: Integrons are important determinants of resistance in faecal E. coli. Plasmids in integron-containing strains may contribute to dispersing resistance genes. There is a need for improved surveillance for resistance and its mechanisms of dissemination and persistence and mobility of resistance genes in the community and clinical settings.

Antibacterial activity of aqueous extracts of selected chewing sticks.

This aim of this study was to determine the antibacterial activity in extracts obtained from various Nigerian chewing sticks. Aqueous extracts from seventeen chewing sticks and the fruit of C. ferruginea, one fruit used in oral hygiene in Nigeria, were screened for antibacterial activity against type cultures of Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. Eleven of the test extracts showed activity against at least two of these referenced organisms. Minimum inhibitory concentrations (MIC) of these eleven extracts against clinical isolates from orofacial infection were determined. All the extracts demonstrated activity against Staphylococcal and Streptococcal isolates. Over half of the extracts were active against Enterobacteriaceae and obligate anaerobic isolates, including Prevotella melaninogenica, Porphyromonas gigivalis, Fusobacterium nucleatum, and Peptostreptococcus prevotii. Extracts of the Vitellaria paradoxa root, Bridellia ferruginea stem and twigs, Garcinia cola stem, Terminalia glaucescens root, Morinda lucida root, and Cnestis ferruginea fruit showed appreciable activity against all classes of bacterial isolates. The extracts of these plants may serve as sources for chemotherapeutic agents for the management of orofacial infections.

A study of the prevalence of diarrhoeagenic Escherichia coli in children from Gwagwalada, Federal Capital Territory, Nigeria.

INTRODUCTION: Diarrhoeagenic Escherichia coli (DEC) are major causes of diarrhoea in Nigeria. This study was conducted to determine the prevalence of diarrhoea caused by DEC within the Federal Capital Territory, Abuja, Nigeria. METHODS: A total of 730 rectal swabs obtained from 201 children with diarrhoea and 529 healthy controls aged 0-24 months were cultured for the isolation of Escherichia coli. All E. coli isolates were investigated by PCR to determine their pathotype. RESULTS: A total of 61 DEC strains were recovered at a rate of 18.4% and 2.6% from children with diarrhoea and healthy controls respectively. The DEC strains recovered were Enteroaggregative Escherichia coli (34.4%), Shiga-toxin producing Escherichia coli (31.1%), Enterotoxigenic Escherichia coli(18.0%), typical enteropathogenic Escherichia coli (15.0%) and Enteroinvasive Escherichia coli (1.6%). Shiga-toxin producing Escherichia coli andEnteroinvasive Escherichia coli were recovered only from children suffering from diarrhoea and the overall prevalence of DEC strains was significantly higher among the children with diarrhoea (P < 0.0001). The number of DEC strains obtained during the dry season was significantly higher (P = 0.012) than the number obtained in the rainy season. CONCLUSION: Diarrhoea caused by E. coli in the Nigerian children studied is associated with several diarrhoeagenic pathotypes and a significant proportion of the healthy children were found to harbour EAEC and ETEC strains. These asymptomatic carriers may be regarded as potential transmitters of infection to vulnerable children in the study area.

The bacteriological quality of different brands of bottled water available to consumers in Ile-Ife, south-western Nigeria.

BACKGROUND: The upsurge in the demand for bottled water has prompted the interest of many manufacturers in the production of bottled water and very many water bottling companies are therefore involved in its production. These range from large scale multinational companies to medium scale business enterprises, institutional and government business investment companies as well as small scale entrepreneurs. There is however little information on the comparative quality of bottled water brands produced by different classes of water bottling companies in Nigeria. This study was undertaken to determine the bacteriological quality of brands of bottled water available to consumers in Ile-Ife. METHODS: Forty-three samples of bottled water comprising of three batches each of thirteen bottled water brands and two batches of two brands were purchased and analyzed for total bacterial count, presence of coliform and the presence of other bacterial indicators of drinking water quality. RESULTS: Only 67.4% of the water samples representing the products of 10 companies or 66.7% of the brands had heterotrophic counts within the acceptable limits. Coliforms present in 100 ml of water were detected in 26.7% of the bottled water brands. Other indicator organisms detected included Staphylococci isolated from 27.9% of the samples (33.3% of the brands) and specifically Staphylococcus aureus found in four brands constituting 14% of the samples. Pseudomonas strains were consistently detected in consecutive batches of three brands of the water samples. CONCLUSIONS: Bottled water samples produced by the large scale multinational producers were of acceptable bacteriological quality unlike those produced by most small companies. SIGNIFICANCE AND IMPACT OF STUDY: There is need for a greater control of water bottling processes carried out by commercial bottled water producers in Nigeria.

Pattern of pathogens from surgical wound infections in a Nigerian hospital and their antimicrobial susceptibility profiles.

BACKGROUND: In surgical patients, infection is an important cause of morbidity and mortality. A prospective study to find the pattern of microorganisms responsible for post operative wound infections and their antibiotic susceptibility profile was therefore conducted. SETTING AND METHODS: Surgical wards in Obafemi Awolowo University Teaching Hospital Complex, Ile-Ife, Nigeria. Isolation, identification and antimicrobial susceptibility screening of organisms were done employing standard microbiological techniques. RESULTS: Bacterial pathogens were isolated from all the specimens while the yeast Candida species (spp) was isolated from 12.4%. Staphylococcus aureus was the most frequent organism isolated accounting for 23 (18.3%) of a total of 126 isolates. Other organisms were Pseudomonas aeruginosa and Bacillus spp 11.1% each; Escherichia coli 10.3%; Candida spp 8.7%; Coagulase negative staphylococci 8.7%; Pseudomonas spp 6.3%; Serratia odorifera 4.7%; Bacteroides 4.0%; Enterococcus spp 3.2%; the remaining isolates were other enterobacteria. Sensitivity of the bacterial isolates to antibiotics varied. In general, resistance to the ß-lactam antibiotics was above 98%, whilst more than 70% of isolates were resistant to erythromycin, fusidic acid and tobramycin. CONCLUSIONS: The infections were polymicrobic and multidrug resistant. The quinolones, ciprofloxacin and ofloxacin, should be used as frontline drugs in the management of surgical wound infections at the hospital.

Dissemination of the transmissible quinolone-resistance gene qnrS1 by IncX plasmids in Nigeria.

The plasmid-encoded quinolone resistance gene qnrS1 was recently found to be commonly associated with ciprofloxacin resistance in Nigeria. We mapped the qnrS1 gene from an Escherichia coli isolate obtained in Nigeria to a 43.5 Kb IncX2 plasmid. The plasmid, pEBG1, was sufficient to confer ciprofloxacin non-susceptibility, as well as tetracycline and trimethoprim resistance, on E. coli K-12. Deletion analysis confirmed that qnrS1 accounted for all the ciprofloxacin non-suceptibility conferred by pEBG1 and tetracycline and trimethoprim resistance could be attributed to tetAR and dfrA14 genes respectively. While it contained a complete IncX conjugation system, pEBG1 was not self-transmissible likely due to an IS3 element inserted between the pilX5 and pilX6 genes. The plasmid was however efficiently mobilizable. pEBG1 was most similar to another qnrS1-bearing IncX2 plasmid from Nigeria, but both plasmids acquired qnrS1 independently and differ in their content of other resistance genes. Screening qnrS1-positive isolates from other individuals in Nigeria revealed that they carried neither pEBG1 nor pNGX2-QnrS1 but that IncX plasmids were prevalent. This study demonstrates that the IncX backbone is a flexible platform that has contributed to qnrS1 dissemination in Nigeria.

Antibiotic resistance and virulence properties in Escherichia coli strains from cases of urinary tract infections.

This study determined E. coli resistance to commonly used antibiotics together with their virulence properties in Ile-Ife, Nigeria. A total of 137 E. coli isolates from cases of urinary tract infection were tested for their sensitivity to commonly used antibiotics and possession of virulence factors using standard methods. Their ability to transfer resistance was also determined. The isolates demonstrated a high and widespread resistance (51.1 % to 94.3 %) to all the antibiotics used except Nitrofurantoin (7.3 %). A total of 50 (36.5 %) of the isolates were resistant to 10 of the eleven antibiotics employed. Sixty three per cent (63 %) of the 107 trimethoprim resistant E. coli transferred their resistances while amoxicillin, gentamycin, augmentin, tetracycline and erythromycin were cotransferred with trimethoprim. Fifty one (37.2 %) of these multi-resistant isolates possessed one or more virulent factors. The study concluded that urinary tract infection due to E. coli in Ile-Ife may be difficult to treat empirically except with nitrofurantoin, due to high resistance to commonly used antibiotics. It is imperative that culture and susceptibility tests be carried out on infecting pathogen prior to treatment, in order to avoid treatment failure and reduce selective pressure that could result in the spread of uropathogenic E. coli in the environment.

Susceptibility of community associated methicillin resistant Staphylococcus aureus isolated from faeces to antiseptics.

INTRODUCTION: The study aimed to investigate the resistance of methicillin resistant Staphylococcus aureus (MRSA), an indicator used in hospitals but isolated from faecal samples of children in the community, to commonly used antibiotics and antiseptic agents. METHODOLOGY: S. aureus isolates were identified by phenotypic and genotypic techniques such as biochemical tests and polymerase chain reaction. Antibiotic susceptibility was investigated using the disc diffusion technique while the agar dilution method was used to determine the minimum inhibitory concentration (MIC) of antiseptics. RESULTS: MRSA showed considerably higher resistance to other antibiotics than methicillin sensitive Staphylococcus aureus (MSSA). Twelve percent of the MSSA were susceptible to all the antibiotics studied while none of the MRSA had this property. A significant difference in susceptibility between MRSA and MSSA to the three antiseptic agents was observed as 68.8%, 75.0% and 100% of MRSA were less susceptible to benzalkonium chloride, chlorhexidine and cetrimide respectively, while 32.0%, 28.0% and 56.0% of MSSA respectively were less susceptible to these agents compared with S. aureus NCTC 6571. Overall, the MICs for the antiseptics were 2-3 times greater in the MRSA than in the MSSA (p < 0.001). CONCLUSION: Results show that the concentration of antiseptics used in the prevention of the transmission of infectious agents may have to be raised to cope with the possible presence of MRSA in patients coming into hospital.

Regional dissemination of a trimethoprim-resistance gene cassette via a successful transposable element.

BACKGROUND: Antimicrobial resistance is a growing international problem. We observed a 50% increase in the prevalence of trimethoprim resistance among fecal Escherichia coli from healthy Nigerian students between 1998 and 2005, a trend to increase that continued in 2009. METHODS AND FINDINGS: A PCR-based screen revealed that 131 (43.1%) of isolates obtained in Nigeria in 2005 and 2009 carried integron-borne dfrA cassettes. In the case of 67 (51.1%) of these isolates, the cassette was a class 1-integron-borne dfrA7 gene, which has been reported at high prevalence from E. coli isolates from other parts of Africa. Complete sequencing of a 27 Kb dfrA7-bearing plasmid from one isolate located the dfrA7 gene within a Tn21-type transposon. The transposon also contained an IS26-derived bla/sul/str element, encoding resistance to ß-lactams, sulphonamides and streptomycin, and mercury resistance genes. Although the plasmid backbone was only found in 12 (5.8%) of trimethoprim-resistant isolates, dfrA7 and other transposon-borne genes were detected in 14 (16.3%) and 32 (26.3%) of trimethoprim resistant isolates collected in Nigeria in 2005 and 2009, respectively. Additionally, 37 (19.3%) of trimethoprim-resistant E. coli isolates collected between 2006 and 2008 from Ghana were positive for the dfrA7 and a transposon marker, but only 4 (2.1%) harbored the plasmid backbone. CONCLUSIONS: Our data point to transposition as a principal mechanism for disseminating dfrA7 among E. coli from Nigeria and Ghana. On-going intensive use of the affordable broad-spectrum antibacterials is likely to promote selective success of a highly prevalent transposable element in West Africa.

Antibiotic resistance of Helicobacter pylori from patients in Ile-Ife, South-west, Nigeria.

BACKGROUND: Helicobacter pylori has become recognized as a major cause of gastroduodenal diseases in man. Evidence indicates that once acquired, H. pylori persists, usually for life unless eradicated by antimicrobial therapy. Over the past few years, we have accumulated some knowledge of the epidemiology of H. pylori in Ile-Ife, South-West Nigeria. In one collaborative study, we detected H. pylori in 195 (73%) patients referred for endoscopy at Obafemi Awolowo University Teaching Hospitals Complex (OAUTHC). Furthermore we have observed a variegated gastric inflammatory response and atrophy including atrophic pangastritis but are yet to demonstrate MALToma in any of our patients. In addition we have demonstrated that dental plaque is a possible source of gastric H. pylori infection and such an endogenous source could account for difficulty in eradication leading to re-infection. Presently, infected patients are treated with standard combination therapy made up of amoxycilin and ciprofloxacin with a proton pump inhibitor/bismuth. Reports however have shown that the incidence of antimicrobial resistance in Helicobacter pylori is a growing problem and which has been linked with failures in treatment and eradication. Given this situation it has become necessary to have information about the susceptibility of isolates to particular antimicrobial agents before the selection of an appropriate treatment regimen. OBJECTIVES: More recently, we sought to study antimicrobial susceptibility of locally isolated H. pylori strains. METHODS: We subjected 32 isolates to antimicrobial susceptibility testing against seven agents. RESULTS: All the isolates showed multiple acquired antimicrobial resistance as they were all resistant to amoxicillin, clarithromycin, metronidazole, while 29/31, 27/31 showed resistance to rifampicin and tetracycline respectively. Five (15.6%) of these isolates showed resistance to ciprofloxacin. CONCLUSIONS: Our findings suggest that H. pylori strains isolated within our study environment have acquired resistance to all the commonly prescribed antibiotics. On the basis of the findings it would be necessary to re-evaluate the eradication treatment regime in our setting.

Etiology of acute diarrhea in adults in southwestern Nigeria.

Stool specimens from 113 adult outpatients with diarrhea in southwestern Nigeria and 63 controls were examined for bacterial and parasitic enteric pathogens. Enterohemorrhagic Escherichia coli (EHEC) (P < 0.02), enteroaggregative E. coli (EAEC) (P < 0.02), and Entamoeba histolytica (P < 0.0002) were significantly associated with diarrhea. Salmonella, Shigella, nontoxigenic Vibrio cholerae, other categories of diarrheagenic E. coli, as well as a variety of helminths were recovered more frequently from the stools of patients than from the stools of controls but did not show a significant association with disease. Multiple pathogens were recovered from 36.3% of specimens, and bloody diarrhea was commonly associated with E. histolytica and diarrheagenic E. coli infections. The majority of EHEC isolates were non-O157 strains that carried the stx(2) gene. Of the 23 EHEC-infected patients, 12 (52.2%) presented during the 10th week of the study. EHEC strains isolated within this cluster were more likely to hybridize with the enterohemolysin gene probe, to be nonmotile and sorbitol positive, and to fail to agglutinate O157 antisera. Pulsed-field gel electrophoresis demonstrated that the only strains with XbaI profiles that occurred more than once were isolated during the 10th and 11th weeks of the study, suggesting an outbreak. The study has demonstrated that E. histolytica, EHEC, and EAEC are important diarrheal pathogens within the study area and that sporadic and epidemic EHEC infections occur in developing as well as developed countries. Routine surveillance for diarrheagenic E. coli, even only at the tertiary-care level, would be useful in identifying outbreaks and assist in identifying environmental reservoirs and transmission routes.