Genetic diversity and clonal patterns among antibiotic-susceptible and -resistant Streptococcus pneumoniae colonizing children: day care centers as autonomous epidemiological units.
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Characterization by antibiotype of the 1,096 Streptococcus pneumoniae recovered from 2,111 nasopharyngeal samples of children attending 16 day care centers (DCCs) in Lisbon, Portugal, and molecular typing of 413 drug-resistant pneumococci (DRPn) and 89 fully drug-susceptible pneumococci (DSPn) has allowed several conclusions. (i) There was an increase in the frequency of DRPn colonizing children in DCCs from 40% in 1996 to 45% in 1997 to 50% in 1998. (ii) Drug resistance spread by cross-transmission of DRPn clones. A few (8 out of 57) DRPn clones were repeatedly isolated from a large number of children in several DCCs and during each period of surveillance, suggesting the epidemic nature of these clones, which included lineages representing internationally spread S. pneumoniae clones. (iii) Dissemination of resistance determinants among pneumococci colonizing the nasopharynx occurred. Association of identical pulsed-field gel electrophoresis patterns with diverse antibiotypes among pneumococci colonizing children suggests that the high prevalence of DRPn involves not only cross-transmission of resistant strains but also dispersal of resistance genes through recombinational mechanisms. (iv) DCCs are autonomous epidemiological units. Among the 413 DRPn, 57 different lineages were detected; these lineages were dispersed among the 16 DCCs to produce unique microbiological profiles for each of the DCCs. Higher genetic diversity and less sharing of clonal types were observed among the DSPn. (+info)
Molecular epidemiology of penicillin-resistant Streptococcus pneumoniae colonizing children with community-acquired pneumonia and children attending day-care centres in Fortaleza, Brazil.
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To study clonal diversity of penicillin-resistant Streptococcus pneumoniae, 161 randomly selected isolates with reduced susceptibility to penicillin, collected from the nasopharynx of children under 5 years of age with community-acquired pneumonia and healthy controls from public day-care and immunization centres in Fortaleza, Brazil, were characterized by microbiological and serological techniques and automated ribotyping. Also included were 44 randomly selected penicillin-susceptible strains and three international reference strains. With automated ribotyping 75 ribopatterns were observed: 50 ribogroups were unique and 25 ribogroups were represented by two or more isolates. Genetic diversity was extensive but some degree of genetic homogeneity was found in strains from children with pneumonia, strains from children in day-care centres, isolates with reduced susceptibility to penicillin and isolates expressing 'paediatric' serogroups. Fourteen (56%) clusters contained both isolates with reduced penicillin susceptibility and penicillin-susceptible isolates, suggesting emergence of penicillin resistance. In general, there was a good correlation between ribogroups and serogroups, but 12 (48%) clusters contained isolates with alternative serogroups. Isolates with such alternative serogroups were more often encountered in penicillin-susceptible strains (41%) than in strains with reduced susceptibility to penicillin (7%). Thirty-eight (19%) isolates (including seven penicillin-susceptible strains) showed ribotypes indistinguishable from those of two international epidemic clones of S. pneumoniae: ribogroup 54-S-1 (15 isolates) with a ribopattern characteristic of the 23F multiresistant 'Spanish/USA' clone and ribogroup 74-S-3 (23 isolates) with a pattern similar to that of the 6B multiresistant 'Spanish' clone. (+info)
Markers of infection, breast-feeding and childhood acute lymphoblastic leukaemia.
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Infections are suspected to play a role in the aetiology of childhood leukaemia. In 1989-95, we evaluated the relation between childhood acute lymphoblastic leukaemia and pre- and postnatal markers of exposure to infection, as well as breast-feeding. A population-based case-control study was carried out in certain regions of Quebec, Canada, in 1989-95 including 491 incident cases diagnosed between 1980 and 1993 and aged between 0 and 9 years. An identical number of healthy controls matched for age, sex and region of residence at the date of diagnosis was included. Having older siblings, mother's use of antibiotics during pregnancy, and being born second or later were all associated with increased risk of leukaemia while early day-care attendance (odds ratio (OR) = 0.49; 95% CI 0.31-0.77), and breast-feeding (OR = 0.68; 95% CI 0.49-0.95) were significantly protective. A marker of population mixing was not a risk factor. When including all variables defining family structure in a model, having older siblings at time of diagnosis was a risk factor among children diagnosed before 4 years of age (OR = 4.54; 95% CI 2.27-9.07) whereas having older siblings in the first year of life was protective among children diagnosed at 4 years of age or later (OR = 0.46; 95% CI 0.22-0.97). (+info)
Early child-care and preschool experiences and the risk of childhood acute lymphoblastic leukemia.
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An infectious etiology for childhood acute lymphoblastic leukemia (ALL) has been suggested, yet few studies have focused on the role of early child care. Day-care histories were examined in a case-control study of ALL in New York State. Cases (n = 255) were diagnosed at one of four referral centers between 1980 and 1991; controls (n = 760) were randomly selected from livebirths in the 31 counties served by the referral centers. Self-administered questionnaires were mailed to the parents of cases and controls in 1995. Day-care histories were censored at the age of diagnosis for cases and at an equivalent date for controls. The odds ratio for children who stayed at home compared with those who attended day care for >36 months was 1.32 (95% confidence interval (CI): 0.70, 2.52); the odds ratios for 1-18 and 19-36 months of day care were 1.74 (95% CI: 0.89, 3.42) and 1.32 (95% CI: 0.64, 2.71), respectively. Elimination of cases with T-cell ALL enhanced the risk. Starting care at an earlier age was not associated with a decreased risk of ALL. These findings do not support the hypothesis that infrequent contact with peers during early childhood could delay exposure to infectious diseases and increase the risk of ALL. (+info)
Outbreaks of human-herpes virus 6 (HHV-6) infection in day-care centers in Belem, Para, Brazil.
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A total of 730 children aged less than 7 years, attending 8 day-care centers (DCCs) in Belem, Brazil were followed-up from January to December 1997 to investigate the occurrence of human-herpes virus 6 (HHV-6) infection in these institutional settings. Between October and December 1997 there have been outbreaks of a febrile- and -exanthematous disease, affecting at least 15-20% of children in each of the DCCs. Both serum- and- plasma samples were obtained from 401 (55%) of the 730 participating children for the detection of HHV-6 antibodies by enzyme-linked immunosorbent assay (ELISA), and viral DNA amplification through the nested-PCR. Recent HHV-6 infection was diagnosed in 63.8% (256/401) of them, as defined by the presence of both IgM and IgG-specific antibodies (IgM+/IgG+); of these, 114 (44.5%) were symptomatic and 142 (55.5%) had no symptoms (p = 0.03). A subgroup of 123 (30.7%) children were found to be IgM-/IgG+, whereas the remaining 22 (5.5%) children had neither IgM nor IgG HHV-6- antibodies (IgM-/IgG-). Of the 118 children reacting strongly IgM-positive (> or = 30 PANBIO units), 26 (22.0%) were found to harbour the HHV-6 DNA, as demonstrated by nested-PCR. Taken the ELISA-IgM- and- nested PCR-positive results together, HHV-6 infection was shown to have occurred in 5 of the 8 DCCs under follow-up. Serological evidence of recent infections by Epstein-Barr virus (EBV) and parvovirus B19 were identified in 2.0% (8/401) and 1. 5% (6/401) of the children, respectively. Our data provide strong evidence that HHV-6 is a common cause of outbreaks of febrile/exanthematous diseases among children attending DCCs in the Belem area. (+info)
Novel penicillin-, cephalosporin-, and macrolide-resistant clones of Streptococcus pneumoniae serotypes 23F and 19F in Taiwan which differ from international epidemic clones.
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A cluster (14 of 18) of Streptococcus pneumoniae serotype 23F isolates that were resistant to penicillin (PEN), cephalosporin, and macrolide was found in one day care center in Kaohsiung, Taiwan. We analyzed the 18 isolates by pulsed field gel electrophoresis (PFGE). All but one serotype 23F isolate demonstrated identical PFGE patterns, which were different from the established pattern of the internationally spread Spanish 23F clone. The three strains of serotype 19F also showed a uniform pattern. These data strongly suggest that two novel clones of PEN-, cephalosporin-, and macrolide-resistant S. pneumoniae serotypes 23F and 19F are present in Taiwan. (+info)
Family size, day-care attendance, and breastfeeding in relation to the incidence of childhood asthma.
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A hypothesis has been suggested stating that children exposed early to infections are less likely to develop atopy or asthma. The authors investigated the relation between risk of childhood asthma and number of siblings as well as day-care attendance, as factors possibly increasing the likelihood of early infections, and breastfeeding as a factor reducing them. A case-control study was carried out in Montreal, Canada, between 1988 and 1995 that included 457 children diagnosed with asthma at 3--4 years of age and 457 healthy controls. Cases followed for 6 years were later classified as persistent or transient by the symptoms and use of medication after diagnosis. Among cases diagnosed at 3--4 years of age, the adjusted odds ratio for asthma was 0.54 (95% confidence interval (CI): 0.36, 0.80) for one sibling and 0.49 (95% CI: 0.30, 0.81) for two or more. The adjusted odds ratio for day-care attendance before 1 year of age was 0.59 (95% CI: 0.40, 0.87). Results were similar with persistent cases. Among transient cases (who possibly had an infection with wheezing at 3--4 years of age), day-care attendance and a short duration of breastfeeding resulted in increased risk. The results support the hypothesis that opportunity for early infections reduces the risk of asthma. (+info)
A study of infectious intestinal disease in England: risk factors associated with group A rotavirus in children.
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OBJECTIVE: To identify risk factors for infectious intestinal disease (IID) due to rotavirus group A in children aged under 16 years. METHODS: Case-control study of cases of IID with rotavirus infection presenting to general practitioners (GPs) or occurring in community cohorts, and matched controls. RESULTS: There were 139 matched pairs. In children under 16 years the following risk factors were significantly associated with rotavirus IID: living in rented council housing (adjusted OR = 3.78, P = 0.022), accommodation with more than five rooms (OR = 0.72, P = 0.002), contact with someone ill with IID (OR = 3.45, P < 0.001). Some foods were associated with decreased risk. In infants, bottle feeding with or without breast feeding was associated with increased risk (OR = 9.06, P < 0.05). CONCLUSIONS: Contact with persons with IID, living in rented council housing and accommodation with fewer rooms, were significant risk factors for sporadic rotavirus IID in children whereas breast feeding is protective in infants. (+info)