Bacterial pathogens associated with diarrhoea on the island of Crete

Stool specimens from 3,600 diarrhoeal patients from the island of Crete, Greece, were examined for bacterial pathogens, during a three-year period (1992-1994). One or more pathogens were identified in 826 patients (22.9%), more often from children. Salmonella spp. were the most frequently isolated organisms in 13.6% of the patients, followed by Campylobacter in 4.7%, and enteropathogenic Escherichia coli (EPEC) in 3.9%. Yersinia enterocolitica was found in 0.7%, Shigella spp. in 0.7% and Aeromonas hydrophila in 0.05%. Vibrio spp. and enterohaemorragic E. coli were not identified in the stools tested. Resistance to ampicillin was observed in 36% of the Salmonella, 62% of the Shigella, and 27% of the EPEC isolates. Cotrimoxazole resistance was observed in 42% of the Shigella and 12% of the EPEC isolates, while tetracycline and the quinolones were inactive against almost half and erythromycin against 20% of the Campylobacter isolates. This is the first study investigating bacterial pathogens associated with diarrhoea on the island of Crete.     

Heart signal recognition by Hidden Markov Models: the ECG case

From December 1989 to May 1990, 315 faecal samples from children under 5 years old with diarrhoea (215) and without diarrhoea (100) seen at paediatric clinics were investigated for bacterial, viral and parasitic enteropathogens. Standard and recently described methods were used for the investigations, which revealed that 74.9% of children with diarrhoea were infected with enteropathogens compared with 28% of controls. In the diarrhoeal group, 59.1% had a bacterial, 26.5% a viral and 2.3% a parasitic aetiology. Rotavirus was the pathogen most frequently detected, accounting for 22.3% of positive findings in the group with diarrhoea versus 9% in the control group. Other important agents were: enterotoxigenic Escherichia coli (ETEC) (14.4 versus 6%), enteropathogenic E. coli (EPEC) (10.7 versus 5%), enteroadherent E. coli (EAEC) (9.3 versus 4%), enterohaemorrhagic E. coli (EHEC) (5.1 versus 3%) and Salmonella spp. (3.3 versus 1%). The following enteropathogens were detected exclusively in the diarrhoeal stools: Shigella spp. (5.1%), Yersinia enterocolitica (0.9%), Aeromonas hydrophila (1.4%), Entamoeba histolytica (0.5%), Giardia lamblia (0.5%), Trichomonas hominis (0.5) and Trichuris trichiura (0.9%). The detection rates of rotavirus, EPEC and EAEC were much greater in the diarrhoeal than in the control patients. No Vibrio cholerae, enteroinvasive E. coli (EIEC), Plesiomonas spp. or Cryptosporidium spp. were detected in this study. Our data suggest that both the traditional and newly recognised diarrhoeal agents are important causes of diarrhoea in the children under 5 years old in Lagos, Nigeria.     

Studies on the bacterial flora of fish which are potential pathogens for human. Virulence factors of potential human pathogen isolated

Tests for various virulence factors, such as production of haemolysin on sheep blood agar plate, cytotoxin on HeLa cell line and enterotoxin in GM-1 ELISA and suckling mouse assay model, were done among the various strains of Aeromonas spp., Vibrio spp., Plesiomonas shigelloides and Esch. coli isolated from fresh water fish samples. Invasive properties of the isolates were also seen by using Sereny test. Haemolysin production was observed in 85.7% of Aeromonas, all (100%) of Vibrios, 13.3% of Esch. coli and none (0%) of P. shigelloides strains. Cytotoxin production was demonstrated in 60.8% of Aeromonas, 38.4% of Vibrios and none (0%) of P. shigelloides and Esch. coli strains. About 8% of Vibrio spp., were found positive for LT in GM-1 ELISA method whereas, none of the Aeromonas spp., Plesiomonas and Esch. coli. strains were found positive for LT and ST in GM-1 ELISA. By suckling mouse assay model 43.4% strains of Aeromonas were found positive for enterotoxin production whereas, strains of Vibrio spp., Plesiomonas and Esch. coli yielded negative results. Sereny test for invasive property was found negative in all the strains tested. The isolates from fish possess various virulence factors which contributes for pathogenicity in order to cause various diseases to susceptible individual.     

Aeromonas-associated gastroenteritis in Egypt

Aeromonas spp. including A. hydrophila, A. sobria, and A. caviae, were recovered from the feces of 88% of diarrheic Egyptian children. In contrast, only 45% of nondiarrheic children contained Aeromonas spp. A probable source of Aeromonas spp. is from drinking water inasmuch as nine out of ten samples analysed from the district of Cairo in which the children resided tested positive for Aeromonas spp. Enterotoxigenicity of the isolates from various sources was tested. 33% of the diarrheic samples produced enterotoxin whereas 47% of the nondiarrheic and 56% of the tap water strains produced enterotoxin.     

Etiological agents of infectious diarrhea: implications for requests for microbial culture

Gastrointestinal infections remain a frequent disease worldwide. In order to increase our knowledge of the epidemiology for our patient population, we retrospectively analyzed the results obtained for stool samples received at the clinical microbiology laboratory of the University Hospital of Geneva during a 4-year period. A total of 13,965 specimens from 7,124 patients (1.96 specimens per patient) were cultured, yielding 369 (2.6%) Salmonella spp., 408 (2.9%) Campylobacter spp., and 79 (0.6%) Shigella spp. The cumulative positivity rate of 6.1% decreased to 2.7% when patients received antimicrobial agents (P < 0.001). The positivity rate for 5,912 specimens obtained from patients hospitalized for < or = 3 days was 12.6%, whereas it dropped to 1.4% for patients hospitalized for > 3 days (P < 0.001). Of 3,837 stool samples originating from pediatric patients, 8.8% were positive, and 5.1% of 10,128 samples from adults were positive (P < 0.001). The cytotoxin of Clostridium difficile was detected in 379 of 3,723 samples analyzed (10.2%), and rotaviruses were detected in 190 of 1,601 samples (11.9%). We recommend that the use of cultures for enteric bacterial pathogens be restricted to patients hospitalized for < or = 3 days, with the exceptions of follow-up samples, specimens from immunocompromised patients, and patients whose first sample was culture negative or in the rare event of nosocomial food-borne outbreaks. For patients under antimicrobial therapy, testing for cytotoxin of C. difficile should primarily be requested; this analysis should also be accepted for samples from patients not receiving antimicrobial agents at the time of specimen collection. By applying these restrictions, we could have saved at least $5,000 annually.     

Medical mummies: the history of the Burns Collection

Of the 43 Aeromonas spp. isolated from various clinical samples 94% isolates were Beta-lactamase producers. The isolates were tested for sensitivity by disc diffusion method which is commonly used in Pakistan. MIC was determined by using Epsilometer test (E-test) method. More than 80% isolates were sensitive to cephalosporins and quinolones. However, resistance to commonly used antibiotics was very high, 94% isolates were resistant to ampicillin which corresponds to the betalactamase production. More than 60% of the isolates were resistant to cotrimoxazole and 40% to chloramphenicol, hence quinolones and cephalosporins appear to be the drugs of choice for treating serious Aeromonas infections. The MIC range of Aeromonas was best for cefotaxime < 0.06 - 1.0 ug/ml. MIC 90 for cefotaxime was 0.50 ug/ml, for imipenem 0.25 ug/ml and for ciprofloxacin 2.0 ug/ml.     

Comparison of a novel microaerobic system with three other gas-generating systems for the recovery of Campylobacter species from human faecal samples

Three commercial gas-generating systems--CampyGen (Oxoid, UK), Oxoid BR56 (Oxoid, UK), and CampyPak Plus (Becton Dickinson, USA)--and the evacuation replacement technique were compared for the recovery of Campylobacter spp. from 500 human faecal samples collected from patients with gastroenteritis. Four hundred fifty faecal samples were tested upon receipt in the laboratory. Fifty faecal samples that had been previously found to be positive for Campylobacter spp. were tested retrospectively; these had been stored at 4 degrees C for more than 48 h. A total of 41 (9.1%) of the fresh faecal samples and 41 of 50 (82%) of the stored faecal samples were positive for thermophilic campylobacters. The CampyGen, the Oxoid BR56, the CampyPak Plus, and the evacuation replacement system detected Campylobacter spp. in 40 (97.6%), 39 (95.1%), 41 (100%), and 41 (100%) of the positive fresh faecal samples and in 37 (90.2%), 40 (97.6%), 39 (95.1%), and 40 (97.6%) of the stored samples, respectively. There was no statistical difference in performance of any of the four gas systems used (p = 0.98; chi-square test). Eighty-six percent of the isolates were Campylobacter jejuni and 14% were Campylobacter coli. Biotyping and phage typing of the isolates demonstrated that they were of a diverse range of subtypes. This study demonstrates that thermophilic campylobacters can be isolated from human diarrhoeal faecal samples using any of the four microaerobic-atmosphere-generating systems.     

Aetiology of acute diarrhoea in hospitalized children in Hong Kong

To determine the role of enteric pathogens in acute childhood diarrhoea in Hong Kong, 388 children with diarrhoea and 306 children of similar age without diarrhoea were evaluated in a hospital-based study during a one-year period from August 1994 to July 1995. Of the diarrhoeal cases, 55% were under 1 year and 95% were below 5 years of age. On admission, 22% had some dehydration but none was severely dehydrated. All children were well nourished. Oyer 60% of children with diarrhoea had one or more pathogens in their stool. Rotavirus was the most commonly isolated pathogen (34.6%), followed by Salmonella (23.3%), Campylobacter (4.7%) and Shigella (2.1%). Rotavirus was not assessed in the controls and was detected mainly during the winter months December to February. Bacterial pathogens were identified more commonly in diarrhoea patients (30%) than in controls (5.6%) (P < 0.001). Despite rapid recent socioeconomic development in Hong Kong, non-typhoidal Salmonella diarrhoea remains a significant local problem in infants under 1 year. Further detailed assessment of the transmission and prevention of this infection is required.     

Occurrence of Protozoan and Bacterial Pathogens in Water Samples from Small Water Systems in Mountainous Areas of Taiwan

Giardia, Cryptosporidium, Salmonella, and Shigella have emerged as waterborne pathogens of concern. Thirty water samples were collected from 10 small water systems in mountainous areas of Taiwan and investigated for the occurrence of these pathogens. In addition, the basic characteristics of each small water system were recorded, and each water sample was tested for several water quality parameters. The occurrence frequency was 10.0% for Giardia spp., 3.3% for Cryptosporidium spp. and Shigella flexneri, and 16.7% for Salmonella enterica. The highest correlation was found between the presence of Salmonella enterica and low water temperature, followed by the correlation between water turbidity and fecal coliform concentration. A low correlation was found between the presence of Giardia and the concentration of heterotrophic bacteria. The water samples from small water systems with filtration devices had a lower occurrence of pathogen microorganisms than those without filtration devices. The proportion of water samples with pathogenic microorganisms increased with the consumer population of the water systems, and the pathogen occurrence differed among the regions of the sampling sites. In order to prevent parasitic infection, the use of disinfection devices in small water systems would be needed.     

Comparison of CHROMagar Salmonella medium and hektoen enteric agar for isolation of salmonellae from stool samples

CHROMagar Salmonella (CAS), a new chromogenic medium, was retrospectively compared to Hektoen enteric agar (HEA) with 501 Salmonella stock isolates and was then prospectively compared to HEA for the detection and presumptive identification of Salmonella spp. with 508 stool samples before and after enrichment. All stock cultures (100%), including cultures of H2S-negative isolates, yielded typical mauve colonies on CAS, while 497 (99%) isolates produced typical lactose-negative, black-centered colonies on HEA. Following overnight incubation at 37 degreesC, a total of 20 Salmonella strains were isolated from the 508 clinical samples. Sensitivities for primary plating and after enrichment were 95% (19 isolates) and 100% (20 isolates), respectively, for CAS and 80% (16 isolates) and 100% (20 isolates), respectively, for HEA. The specificity of CAS (88.9%) was significantly higher than that of HEA (78.5%; P < 0.0001). On the basis of its good sensitivity and specificity, CAS medium can be recommended for use for primary plating when human stool samples are screened for Salmonella spp.     

Giardiasis in travellers: evaluation of an antigen-capture ELISA for the detection of Giardia lamblia-antigen in stool

Diagnosis of giardiasis relies largely on the microscopical detection of trophozoites or cysts in feces. However, this method is labour- and time-intensive and depends highly on the skill of an experienced microscopist. In order to identify the prevalence of Giardia lamblia in travellers returning from overseas, we evaluated sensitivity and specificity of a commercially available ELISA kit for the detection of Giardia-lamblia-antigen in stool. Nine hundred seventy-eight stool samples from 795 patients were examined by microscopy (iron-hematoxyilin-stain, SAF-concentration) and ELISA. Altogether, Giardia infection could be detected in 74 subjects. On evaluation of all samples, the ELISA turned out to be more sensitive than microscopy (95.5% vs. 81.8%) and 99.7% specific for Giardia lamblia. Especially with microscopy, the examination of more than one stool specimen did improve diagnostic sensitivity. It seems therefore advisable to retain the practise of examining at least three stool samples before considering a patient as not infected. The coproantigen-ELISA is especially advantageous in situations where only a single stool sample can be examined. It should not, however, replace microscopical examination of stool specimens for ova and parasites since other potential pathogens would otherwise escape detection.     

Population dynamics of Aeromonas spp. in an urban river watershed

Density of Aeromonas spp. at one site in the Buffalo River and at four sites on its upstream tributaries was followed from June 1992-June 1993. Membrane filtration counts of Aeromonas during the summer ranged between 18 and 4000 ml-1, which were one to two logs higher than faecal coliform and faecal streptococci densities. Aeromonas spp. in the Buffalo River, and faecal coliforms, faecal streptococci, and the heterotrophic plate count throughout the watershed, increased by approximately one log during summer rainstorms. However, Aeromonas spp. increased only by a factor of two during rainstorms at the upstream sites. Aeromonas spp. showed a strong positive correlation with both indicator bacteria and total suspended solids at the upstream sites during the summer but not the winter. Correlations between Aeromonas and indicator bacteria remained strong in the Buffalo River during the winter, signifying that different conditions exist in the Buffalo River and its upstream tributaries. The strong correlation between Aeromonas spp. and indicator bacteria in the Buffalo River suggest that, in the absence of media capable of the quantitative recovery of potentially pathogenic aeromonads, standard faecal coliform analyses may adequately assess public health risks from Aeromonas spp. in an urban river used for recreational purposes.     

Flies and water as reservoirs for bacterial enteropathogens in urban and rural areas in and around Lahore, Pakistan

The study was conducted to isolate and characterize campylobacter, enterotoxigenic Escherichia coli-labile toxin (ETEC-LT), shigella and salmonella in flies and water. The material for the study, flies (n = 300) and water samples (n = 148), was collected from different localities in and around Lahore, Pakistan. Cultivation of the samples was performed on conventional standard media. Membrane filtration technique was used for water prior to culture. Determination of ETEC-LT was done by GM1 ELISA. Results of our study showed that flies and water were reservoirs for all the four pathogens, campylobacter, ETEC-LT, shigella and salmonella. Flies from the village were carrying fewer enteropathogens, while water from the village was found to be more contaminated as compared to the city. Campylobacter and ETEC-LT were the most frequently isolated pathogens in both flies and water. Thus the incidence of diarrhoeal disease in children of developing countries may be decreased by providing plenty of safe drinking water, improving excreta disposal, toilet facilities and giving education in personal hygiene.     

Aeromonas popoffii sp. nov., a mesophilic bacterium isolated from drinking water production plants and reservoirs

We examined the taxonomic position of seven Aeromonas isolates, recovered from Flemish and Scottish drinking water production plants and reservoirs, which were previously recognized by numerical analysis of genomic AFLP fingerprints as members of an unknown Aeromonas taxon that most closely resembled the species Aeromonas bestiarum (DNA hybridization group [HG] 2). The new phenotypic and DNA-DNA hybridization data obtained in this study show that the A. bestiarum-like strains constitute a separate Aeromonas species, for which the name Aeromonas popoffii sp. nov. is being proposed. The new species exhibited an internal DNA relatedness ranging from 79 to 100% and was 22 to 63% related to the type or reference strains of other Aeromonas spp. The highest DNA binding values were determined with A. bestiarum (51 to 63%), followed by Aeromonas hydrophila sensu stricto (HG1; 50 to 60%) and Aeromonas salmonicida (HG3; 39 to 55%). Although fingerprints generated by ribotyping and cellular fatty acid analysis often were highly similar, minor differences between the respective fingerprints were of significance for the differentiation of A. popoffii from its closest taxonomic neighbors, HG1, HG2, and HG3. Phenotypically, all seven strains of A. popoffii were positive for acid and gas production from D-glucose and glycerol, growth in KCN broth, arginine dihydrolase, DNase, Voges-Proskauer reaction, and resistance to vibriostatic agent O/129 and ampicillin but displayed negative reactions for production of urease, tryptophan deaminase, ornithine decarboxylase, and lysine decarboxylase (LDC). None of the strains displayed strong hemolytic activity. The lack of D-sucrose fermentation and LDC production and the ability to utilize DL-lactate as the sole energy and carbon source were useful characteristics for the biochemical separation of A. popoffii from A. bestiarum. Other Aeromonas spp. could be differentiated phenotypically from the new species by at least two features. The chromosomal G+C content of A. popoffii ranges from 57.7 to 59.6 mol%. Strain LMG 17541 is proposed as the type strain.     

Molecular biology detection and antibiotic sensitivities of Shigella spp. and entero-invasive Escherichia coli (EIEC) in patients returning from the tropics

1579 stool samples from patients with travel-associated diarrhea were examined by conventional culture methods to detect Shigella spp. (48 positive samples or 3.2%) and by PCR to detect shigellae and enteroinvasive Escherichia coli (EIEC) (87 positive samplers or 5.8%). The numerical relation of shigellae to EIEC in PCR-positive samples was about 60 to 40%. However, the lack of discrimination between shigellae and EIEC is not important for the physician because the choice of antibiotics remains the same.     

Treatment of parkinsonism. Views on the recommendations issued by the Medical Products Agency

Direct detection of Escherichia coli O157 and foodborne pathogens associated with bloody diarrhea were achieved using polymerase chain reaction (PCR) after the preparation of DNA from stool specimens using the microspin technique. PCR was compared with cultivation and toxin production tests with respect to the efficiency of detection of each pathogen; E. coli O157, Vibrio parahaemolyticus, Salmonella serovar Enteritidis and Campylobacter jejuni. Detection of some or all of the above pathogens in clinical stool specimens was achieved using PCR. The minimum number of cells required for the detection of the above pathogens by PCR was 10(1) CFUs/0.5 g of stool sample. PCR was completed within 6 hr. The above pathogens were also detected in cultivation and toxin production tests. Partial purification of the template DNA using the microspin technique was essential for the elimination of PCR inhibitors from the DNA samples. This PCR method is an accurate, easy-to-read screening method for the detection of Shiga-like toxin producing E. coli O157 and enteropathogens associated with bloody diarrhea in stool specimens.     

Non operative treatment of liver and spleen trauma. Clinical experience

A commercially available ELISA kit was used for the detection of Bacillus diarrhoeal enterotoxin (BDE) in a variety of foods and faeces. The ability of isolates of Bacillus spp., including Bacillus cereus, to produce BDE in Brain Heart Infusion broth containing 0.1% glucose was also checked by use of the kit. Results show that 29 out of 31 B. cereus isolates were enterotoxigenic. Foods positive for performed BDE were always contaminated with > 10(5) B. cereus cfu g-1, but not all foods contaminated with large numbers of B. cereus were positive for BDE. Bacillus sp., other than one isolate which closely resembled B. subtilis, were negative for BDE production. Criteria for the confirmation of Bacillus-mediated diarrhoea should now include reports of symptoms and incubation periods consistent with the diarrhoeal form of food-poisoning by Bacillus spp., together with the results of tests for enterotoxigenicity of the Bacillus isolate, and detection of BDE in either the food and/or faeces.     

Private business: the uptake of confidential HIV testing in remote aboriginal communities on the Anangu Pitjantjatjara Lands

Bacterial populations associated with three sample types from the neck region of poultry carcasses in the dirty area of an abattoir were characterized. Sample types before and after scalding were skin only, feathers only, and a skin and feather combination. The neck skin of carcasses after the defeathering processing stage was also sampled. Bacterial populations associated with water from the scald tank, rubber fingers at the exit of the defeathering machine, and air in the dirty area were also characterized. Bacterial colonies (751) were randomly isolated from yeast extract-supplemented tryptone soya agar plates exhibiting 30 to 300 colonies. Micrococcus spp. were isolated in the highest proportion from pre-and postscalded carcass samples (63.5 to 86.1% of isolates), regardless of the sample type. Conversely, Enterobacteriaceae (40.3%), Acinetobacter (19.4%), and Aeromonas/Vibrio (12.5%) species predominated on neck skin samples taken from mechanically defeathered carcasses. Isolates from the rubber fingers were, however, predominantly Micrococcus spp. (94.4%). Bacterial groups isolated in the highest proportion from scald tank water samples were Micrococcus spp. (38.3%), species of Enterobacteriaceae (29.1%), and lactic acid bacteria (17.0%). Corynebacterium spp., species of Enterobacteriaceae, and Micrococcus spp. were dominant on air settle plates.     

Prevalence and sensitivity to antibiotics of Enterobacteriaceae isolated from urinary cultures in some microbiology laboratories of a city in west Greece

The prevalence of Enterobacteriaceae from midstream urine samples from patients with community acquired urinary tract infections (UTI) of a town in SW Greece during one year period and their susceptibility to antibiotics were studied. The most frequently recovered pathogens were E. coli (77%), Proteus mirabilis (10%), Klebsiella spp (8.7%), Enterobacter spp (2.5%) and Citrobacter freundii (1.8%). E. coli were found more resistant to carbenicillin, the combination of amoxicillin/clavulanic acid and cotrimoxazole. Half of the strains were found resistant to more than one antibiotics. All strains were found sensitive to aminoglucosides, 2nd generation cephalosporines (except cefoxitin), 3rd generation cephalosporines, aztreonam and imipeneme. According to our results a statistically significant increase of the resistance to antibiotics at individuals over 45 years of age was noticed. The positivity of the samples was not correlated to prior antibiotic consumption and to the occupation of the participants or their residence.