Eighty-four clinical isolates of the family

Nasopharyngeal carriage of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis in 226 children in different settings (in a crèche [day care center], in an orphanage, and at home) during two seasons (winter and spring) was studied. The rates of carriage of S. pneumoniae and H. influenzae were markedly higher in the crèche and in the orphanage than in the home setting (e.g., 56.5, 63.3, and 25.9%, respectively, for S. pneumoniae in winter). Approximately 80% of the S. pneumoniae isolates identified in the crèche and in the orphanage belonged to the serotypes represented in the seven-valent pneumococcal vaccine, and 4.4% of the children were colonized by H. influenzae type b. Almost all H. influenzae isolates were fully susceptible to the antimicrobial agents tested, and only five (3.6%) produced ␤-lactamase; in contrast, 100% of the M. catarrhalis isolates were ␤-lactamase positive. Among S. pneumoniae isolates, 36.2% were nonsusceptible to penicillin (PNSP) and 11.8% were fully resistant to penicillin (PRP). All PNSP isolates were obtained from children at the crèche and at the orphanage but not among children brought up at home, and all PRP isolates showed a multiresistant phenotype. Colonization by PRP isolates correlated well with prior treatment with ␤-lactams. For the majority of children colonized at both sampling times, strain replacement of S. pneumoniae and H. influenzae was observed; long-term colonization by a single strain was rare.The nasopharynx of children is colonized by a broad variety of microorganisms, including such potential pathogens as Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Well-known risk factors that promote bacterial carriage include overcrowding, e.g., due to attending day care centers (DCCs) (crèches) or residing in orphanages; frequent viral infections; and an excessive use of antibiotics (12). DCCs and orphanages have also been identified as places that promote the clonal spread of multiresistant strains; thus, healthy children represent an important reservoir of bacterial strains, in particular, S. pneumoniae, that are resistant to many antimicrobial agents. These strains are subsequently disseminated in the community by other contacts of colonized children, e.g., their siblings and parents. It is possible to limit the spread of H. influenzae type b and some serotypes of S. pneumoniae by vaccination, but studies of the impact of immunization on colonization have yielded discrepant results (5,11,14,22).Colonization of mucosal surfaces in the human respiratory tract represents a dynamic process in which bacteria are acquired, eliminated, and reacquired many times in a lifetime. Extensive and often excessive use of antibiotics can promote the replacement of strains susceptible to antimicrobial agents by resistant ones (12, 28). Moreover, the human nasopharynx is also often viewed as a place where frequent genetic exchange takes place due to such processes as transformation with foreign DNA, bacterial intra-and interspecies c...

A Klebsiella pneumoniae epidemic strain that coproduced carbapenemase KPC-2 (K. pneumoniae carbapenemase 2) and 16S rRNA methylase ArmA has emerged in Poland. Four nonduplicate isolates from patients in a hospital in Warsaw, Poland, were found to carry the bla KPC-2 and armA genes on ca. 50-kb and 90-kb plasmids, respectively. Tn4401 with a 100-bp deletion in the variable region was detected in all the isolates. XbaI pulsed-field gel electrophoresis (PFGE) revealed 93.2% similarity of the isolates. All the isolates were resistant to carbapenems and 4,6-disubstituted 2-deoxystreptamines.

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