Longitudinal evaluation of serovar-specific immunity to Neisseria gonorrhoeae.
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The serovars of Neisseria gonorrhoeae that are predominant in a community change over time, a phenomenon that may be due to the development of immunity to repeat infection with the same serovar. This study evaluated the epidemiologic evidence for serovar-specific immunity to N. gonorrhoeae. During a 17-month period in 1992-1994, all clients of a sexually transmitted disease clinic in rural North Carolina underwent genital culture for N. gonorrhoeae. Gonococcal isolates were serotyped according to standard methods. Odds ratios for repeat infection with the same serovar versus any different serovar were calculated on the basis of the distribution of serovars in the community at the time of reinfection. Of 2,838 patients, 608 (21.4%; 427 males and 181 females) were found to be infected with N. gonorrhoeae at the initial visit. Ninety patients (14.8% of the 608) had a total of 112 repeat gonococcal infections. Repeat infection with the same serovar occurred slightly more often than would be expected based on the serovars prevalent in the community at the time of reinfection, though the result was marginally nonsignificant (odds ratio = 1.5, 95% confidence interval 1.0-2.4; p = 0.05). Choosing partners within a sexual network may increase the likelihood of repeat exposure to the same serovar of N. gonorrhoeae. Gonococcal infection did not induce evident immunity to reinfection with the same serovar. (+info)
Serotypes and virulence factors of Escherichia coli strains isolated from dogs and cats.
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E. coli strains isolated from urine of dogs and cats with urinary tract infections (UTI) and from feces of healthy one's were serotyped, and the serotypes were correlated with uropathogenic virulence factors. The most prevalent O-serotypes, O4 and O6, were isolated from dogs and cats with UTI. In contrast, O11 and O102 strains were the most frequently found from feces of healthy dogs and cats. Most of type O4 and O6 strains possessed such virulence factors as pil, pap, sfa, hly, and cnf1, while most type O11 and O102 strains pil only or pil and aer. All strains of type O75 possessed afaI and aer. K1 antigen was negative in all strains obtained from UTI. (+info)
Ribotypes of clinical Vibrio cholerae non-O1 non-O139 strains in relation to O-serotypes.
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The emergence of Vibrio cholerae O139 in 1992 and reports of an increasing number of other non-O1 serogroups being associated with diarrhoea, stimulated us to characterize V. cholerae non-O1 non-O139 strains received at the National Institute of Infectious Diseases, Japan for serotyping. Ribotyping with the restriction enzyme BglI of 103 epidemiological unrelated mainly clinical strains representing 10 O-serotypes yielded 67 different typing patterns. Ribotype similarity within each serotype was compared by using the Dice coefficient (Sd) and different levels of homogeneity were observed (serotypes O5, O41 and O17, Sd between 82 and 90%: serotypes O13 and O141 Sd of 72; and O2, O6, O7, O11, O24 Sd of 62-66%). By cluster analysis, the strains were divided into several clusters of low similarity suggesting a high level of genetic diversity. A low degree of similarity between serotypes and ribotypes was found as strains within a specific serotypes often did not cluster but clustered with strains from other serotypes. However, epidemiological unrelated O5 strains showed identical or closely related ribotypes suggesting that these strains have undergone few genetic changes and may correspond to a clonal line. Surprisingly, 10 of 16 O141 strains studied contained a cholera toxin (CT) gene, including 7 strains recovered from stool and water samples in the United States. This is to our knowledge the first report of CT-positive clinical O141 strains. The closely related ribotypes shown by eight CT-positive strains is disturbing and suggest that these strains may be of a clonal origin and have the potential to cause cholera-like disease. Despite the low degree of correlation found between ribotypes and serotypes, both methods appears to be valuable techniques in studying the epidemiology of emerging serotypes of V. cholerae. (+info)
Emergence of multidrug-resistant Salmonella enterica serotype Typhimurium phage-type DT104 among salmonellae causing enteritis in Israel.
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The relative frequency of salmonella strains isolated from hospitalized and non-hospitalized patients in Southern Israel changed during the period, 1994-6. Salmonella enterica serotype Typhimurium definitive phage-type 104 (DT104) appeared in Israel in 1994 and became the most prevalent strain in 1996. An outbreak of enteritis due to Salmonella enterica serotype Agona occurred in Israel, in October 1994 and lasted for 4 months. The relative frequency of Salmonella enterica serotype Enteritidis remained almost constant during these years, with seasonal fluctuations only. The importance of the increase in the prevalence of Typhimurium DT104 has been the epidemic spread of a multiresistant strain of R-type ACT (A, ampicillin; C, chloramphenicol; T, tetracycline) belonging to this phage-type. Since 1995 the frequency of Typhimurium DT104 isolates that possess, in addition to the above R-type, a chromosomally encoded resistance to the quinolone drug, nalidixic acid, increased tenfold. In 1996, 27% of the Typhimurium DT104 isolates were of R-type ACTN. S. Enteritidis exhibited over 95% susceptibility to at least eight of the most commonly used antibiotic drugs, and none of the isolates was resistant to quinolone or fluoroquinoline. (+info)
Risk factors for the occurrence of sporadic Salmonella enterica serotype enteritidis infections in children in France: a national case-control study.
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To determine risk factors associated with the occurrence of sporadic cases of Salmonella enteritidis infections among children in France, we conducted a matched case-control study. Cases were identified between 1 March and 30 September 1995. One hundred and five pairs of cases and controls matched for age and place of residence were interviewed. In the 1-5 years age group, illness was associated with the consumption of raw eggs or undercooked egg-containing foods (OR 2.4, 95% CI 1.2-4.8). Storing eggs more than 2 weeks after purchase was associated with Salmonella enteritidis infection (OR 3.8, 95% CI 1.4-10.2), particularly during the summer period (OR 6.0, 95% CI 1.3-26.8). Cases were more likely to report a case of diarrhoea in the household 10-3 days before the onset of symptoms, particularly in the age group < or = 1 year (P = 0.01). This study confirms the link between eggs and the occurrence of sporadic cases of Salmonella enteritidis among children, highlights the potential role of prolonged egg storage and underlines the role of person-to-person transmission in infants. (+info)
High turnover rate of Escherichia coli strains in the intestinal flora of infants in Pakistan.
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The Escherichia coli flora of infants in developed countries is dominated by one or a few strains which persist for prolonged periods of time, but no longitudinal studies have been performed in developing countries. To this end, we studied the rectal enterobacterial flora in 22 home-delivered Pakistani infants during their first 6 months of life. Three colonies were isolated and species typed on each of 11 sampling occasions. E. coli isolates were strain typed using electromorphic typing of cytoplasmic enzymes, and their O serogroups were determined. There was a very rapid turnover of enterobacterial strains in the rectal flora of individual infants. On average, 8.5 different E. coli strains were found per infant, and several biotypes of other enterobacteria. Less than 50% of the infants were colonized with E. coli from their mothers, but strains of maternal origin were four times more likely to persists in the infants' flora than other E. coli strains. Enterobacteria other than E. coli were always of non-maternal origin, and Enterobacter cloacae and Klebsiella pneumoniae biotypes recovered from contaminated feeds were later identified in the infants' rectal flora. An early colonization with klebsiella or enterobacter was significantly associated with diarrhoea during the neonatal period, although these bacteria were not likely to be the cause of the disease. The results suggest that poor hygienic conditions result in an unstable and diverse enterobacterial flora, which may influence infant health. (+info)
Infection rate of Leptospira interrogans in the field rodent, Apodemus agrarius, in Korea.
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Leptospirosis has significantly decreased in Korea since 1988, following the leptospiral vaccination programme initiated in 1988. Whether this wholly explains the decreased incidence is uncertain. As an initial step to answer this question, infection rates of Leptospira interrogans in field rodents, Apodemis agrarius, were examined and compared with previous data. Two hundred and twenty-two A. agrarius were captured during October-December 1996. Spirochaetes were isolated from 22 (9.9%) and leptospiral DNA was detected in an additional 6 rodents (12.6%). Subsequent microscopic agglutination tests (MAT) classified all these isolates as L. interrogans serogroup Icterohaemorrhagiae serovar lai. The above data did not significantly differ from previous surveys in 1984-7. There was no significant change of L. interrogans infection in field rodents following the introduction of the vaccination programme in Korea. Further studies are needed to determine the role of human vaccination in reducing incidence. (+info)
Biodiversity of Lactococcus garvieae strains isolated from fish in Europe, Asia, and Australia.
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Lactococcus garvieae (junior synonym, Enterococcus seriolicida) is a major pathogen of fish, producing fatal septicemia among fish species living in very diverse environments. The phenotypic traits of L. garvieae strains collected from three different continents (Asia, Europe, and Australia) indicated phenotypic heterogeneity. On the basis of the acidification of D-tagatose and sucrose, three biotypes were defined. DNA relatedness values and a specific PCR assay showed that all the biotypes belonged to the same genospecies, L. garvieae. All of the L. garvieae strains were serotyped as Lancefield group N. Ribotyping proved that one clone was found both in Japan, where it probably originated, and in Italy, where it was probably imported. PCR of environmental samples did not reveal the source of the contamination of the fish in Italy. Specific clones (ribotypes) were found in outbreaks in Spain and in Italy. The L. garvieae reference strain, isolated in the United Kingdom from a cow, belonged to a unique ribotype. L. garvieae is a rising zoonotic agent. The biotyping scheme, the ribotyping analysis, and the PCR assay described in this work allowed the proper identification of L. garvieae and the description of the origin and of the source of contamination of strains involved in outbreaks or in sporadic cases. (+info)