Patterns of antibiotic-resistant Streptococcus pneumoniae in children in a day-care setting.

BACKGROUND: Streptococcus pneumoniae is one of the primary causes of illness and death among young children, and evidence suggests that the prevalence of antibiotic-resistant S pneumoniae is increasing. The purpose of this study was to investigate the prevalence of antibiotic-resistant S pneumoniae in a sample of children in day-care facilities in a region that includes both rural and urban communities. METHODS: Nasopharyngeal cultures were obtained from 104 children in eight day-care centers located in rural and urban central Kentucky in April and May, 1997. Thirty-five of the children produced isolates positive for S pneumoniae. Each isolate was tested for susceptibility to penicillin, trimethoprim-sulfamethoxazole, erythromycin, tetracycline, vancomycin, and cefotaxime. RESULTS: Of the children with S pneumoniae isolates, 54% had isolates that were resistant to penicillin and 40% that were resistant to trimethoprim-sulfamethoxazole. Twenty-one (60%) of the isolates had resistance to at least one of the six tested antimicrobials, with 15 (43%) having resistance to more than one of the antimicrobials. The mean age of children with isolates resistant to penicillin was significantly less (2.7 + 1.6) than those with penicillin-susceptible isolates (3.7 + 1.1, P = .02). There was no relation between resistance and rural or urban day-care location. CONCLUSIONS: A substantial proportion of S pneumoniae isolates in young children are resistant to antibiotics. Limiting the effect of S pneumoniae drug resistance may require a reexamination of outpatient treatment strategies for childhood respiratory tract infections.

Levofloxacin selects fluoroquinolone-resistant methicillin-resistant Staphylococcus aureus less frequently than ciprofloxacin.

Seventeen methicillin-resistant Staphylococcus aureus (MRSA) with unique genotypes were examined to determine if resistance occurs more frequently with ciprofloxacin or levofloxacin. The mean single-step resistance rate to 4 x MIC of ciprofloxacin was 1.05 x 10(-5) (range <4.82 x 10[-11] to 5.06 x 10[-5]), and that to levofloxacin was 4.03 x 10(-6) (range <3.57 x 10[-13] to 4.10 x 10[-5]) (P < 0.05). When serially passaged, the mean MICs of ciprofloxacin and levofloxacin increased 3.0 +/- 1.5-fold and 1.8 +/- 1.4-fold, respectively (P < 0.05). Only four strains became resistant to levofloxacin, but eight became resistant to ciprofloxacin (P < 0.05). Ciprofloxacin selects resistant MRSA more frequently than levofloxacin.

Ceramide modulates nicotinic receptor-dependent Ca(2+) signaling in rat chromaffin cells.

Ceramide, which is an integral component of the sphingomyelin signaling pathway, can attenuate voltage-gated Ca(2+) channel (VGCC) activity in a number of cell types. The aim of the present study was to determine whether ceramide can also modulate VGCC activity, and as a consequence nicotinic receptor-dependent Ca(2+) signaling and catecholamine secretion, in rat adrenal chromaffin cells. Short-term C(6)-ceramide (CER) treatment dose-dependently inhibited nicotine (NIC)-induced peak intracellular Ca(2+) transients. Sphingomyelinase elicited similar responses, whereas the inactive ceramide analog C(2)-dihydroceramide had no effect on NIC-induced Ca(2+) transients. CER suppressed KCl- and NIC-induced Ca(2+) transients to a similar extent, suggesting that the voltage-gated Ca(2+) channel was a primary site of inhibition. In direct support of this concept, whole-cell patch-clamp analysis demonstrated that CER and sphingomyelinase significantly reduced peak Ca(2+) currents. Pretreatment with staurosporine significantly attenuated CER-dependent inhibition of both NIC-induced Ca(2+) transients and peak Ca(2+) current, suggesting that the effects of CER are mediated at least in part by protein kinase C. Consistent with suppressed Ca(2+) signaling, CER also significantly inhibited NIC-induced catecholamine secretion measured at the single-cell level by carbon fiber amperometry. This effect of CER was also significantly attenuated by pretreatment with staurosporine These data demonstrate that the sphingomyelin signaling pathway can modulate nicotinic receptor-dependent Ca(2+) signaling and catecholamine secretion in rat chromaffin cells.

Molecular epidemiology of multiply antibiotic-resistant Shigella flexneri in Fortaleza, Brazil.

In northeastern Brazil, strains of Shigella flexneri resistant to multiple antibiotics are often found in patients in both urban areas and community hospitals. This study used pulsed-field gel electrophoresis (PFGE) and plasmid analysis to further analyze the molecular epidemiology of Shigella flexneri strains isolated from hospitals and an urban community in Fortaleza, Brazil. Twenty-six strains of S. flexneri from three distinct areas in the city of Fortaleza, Brazil, were examined: 14 strains from people with diarrhea who lived in an urban community of 2,000 persons, 5 strains from patients in the university hospital, and 7 strains from children in a pediatric hospital. PFGE identified six unique groups of S. flexneri circulating among patients during the 45-month study. Seven strains were further studied for antibiotic resistance plasmid profiles. Three unique antibiotic resistance plasmid profiles were found. Strains collected from the hospitalized patients demonstrated the variety of PFGE and antibiotic resistance patterns in the area. Strains collected from the patients living in the urban community setting demonstrated the persistence of certain PFGE patterns as well as the acquisition of multiple antibiotic resistance plasmids. Effective interventional strategies for such geographic locations as Fortaleza, Brazil, will be more complex than those for single-strain outbreak situations.