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ABSTRACTCharacterization by antibiotype of the 1,096 Streptococcus pneumoniaerecovered 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. pneumoniaeclones. (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.

ABSTRACTWe previously characterized over 100 Staphylococcus sciuriisolates, mainly of animal origin, and found that they all carried a genetic element (S. sciuri mecA) closely related to the mecAgene of methicillin-resistantStaphylococcus aureus(MRSA) strains. We also found a few isolates that carried a second copy of the gene, identical to MRSAmecA. In this work, we analyzed a collection of 28 S. sciuristrains isolated from both healthy and hospitalized individuals. This was a relatively heterogeneous group, as inferred from the different sources, places, and dates of isolation and as confirmed by pulsed-field gel electrophoresis analysis. All strains carried the S. sciuri mecAcopy, sustaining our previous proposal that this element belongs to the genetic background ofS. sciuri. Moreover, 46% of the strains also carried the MRSA mecAcopy. Only these strains showed significant levels of resistance to beta-lactams. Strikingly, the majority of the strains carrying the additional MRSA mecAcopy were obtained from healthy individuals in an antibiotic-free environment. Most of the 28 strains were resistant to penicillin, intermediately resistant to clindamycin, and susceptible to tetracycline, erythromycin, and gentamicin. Resistance to these last three antibiotics was found in some strains only. The findings reported in this work confirmed the role of S. sciuriin the evolution of the mechanism of resistance to methicillin in staphylococci and suggested that this species (like the pathogenic staphylococci) may accumulate resistance markers for several classes of antibiotics.

ABSTRACTA national surveillance conducted in Colombia between 1994 and 1996 identified serotype 5 Streptococcus pneumoniaeas the second most frequent cause of invasive disease in children younger than 5 years of age. All 43 serotype 5 isolates collected during this period were shown to be susceptible to penicillin, erythromycin, cefotaxime, and vancomycin, but most (38 of 43, or 88%) were highly resistant to chloramphenicol. In order to clarify a possible genetic relatedness among these isolates, additional microbiological and molecular characterizations were performed. Most (40 of 43, or 93%) of the isolates were found to be resistant to tetracycline. Pulsed-field gel electrophoresis (PFGE) patterns of chromosomal DNAs revealed that all the 43 isolates were closely related and that 38 of the 43 isolates were representatives of a “Colombian clone” of S. pneumoniaeisolates which were recovered throughout the 3-year surveillance period from patients in 13 hospitals located in five Colombian cities. Isolates belonging to this Colombian clone were resistant to chloramphenicol and tetracycline, hybridized with thecatand tetMDNA probes in the same 340-kbSmaI fragment, and had identical PFGE patterns after bothSmaI and ApaI digestions.