Ciprofloxacin susceptibility reduction of salmonella strains isolated from outbreaks

The antimicrobial susceptibility of 212 Salmonella strains isolated from patients and foods was evaluated and 45 percent were found to be resistant to nalidixic acid. Nalidixic acid resistant strains showed a higher minimal inhibitory concentration for ciprofloxacin than sensitive strains. During the study an increase of strains with reduced susceptibility to ciprofloxacin was also observed.

Alta prevalência de crianças portadoras de Streptococcus pneumoniae resistentes à penicilina em creches públicas / High prevalence of children colonized with penicillin-resistant Streptococcus pneumoniae in public day-care centers

OBJETIVOS: Investigar a prevalência de Streptococcus pneumoniae (pneumococos) na nasofaringe de crianças sadias atendidas em creches municipais da cidade de Umuarama (PR). Avaliar a susceptibilidade aos antimicrobianos dos pneumococos isolados. MÉTODOS: Secreção da nasofaringe de 212 crianças foi coletada no período de abril a outubro de 2008. Após semeadura dos espécimes em ágar sangue e incubação a 37 °C por 24-48 horas, as colônias suspeitas de pertencerem a S. pneumoniae foram identificadas pela α-hemólise, sensibilidade à optoquina e bile solubilidade. A susceptibilidade à penicilina foi investigada pelos testes de disco-difusão e de diluição. A susceptibilidade aos demais antimicrobianos indicados no tratamento das infecções pneumocócicas foi realizada por disco-difusão RESULTADOS: A prevalência de pneumococos na nasofaringe foi de 43,4 por cento (92/212), sendo maior em crianças com idade entre 2 e 5 anos (p = 0,0005). Não houve diferença significativa entre os sexos. Resistência intermediária e resistência plena à penicilina foram encontradas respectivamente em 34,8 (32/92) e 22,8 por cento (21/92) dos isolados. Sessenta e sete amostras (72,8 por cento) foram resistentes ao sulfametoxazol-trimetoprim, oito (8,7 por cento) à eritromicina e seis (6,5 por cento) à tetraciclina. Uma amostra apresentou resistência à clindamicina (1,1 por cento), e outra ao cloranfenicol (1,1 por cento). Todas as amostras foram sensíveis a levofloxacina, ofloxacina, rifampicina, telitromicina, linezolide e vancomicina. Nove amostras foram consideradas multirresistentes, por apresentarem resistência a três ou mais classes de antimicrobianos. CONCLUSÕES: O presente estudo registrou uma alta prevalência de crianças portadoras sadias de amostras de S. pneumoniae resistentes à penicilina que podem constituir importantes reservatórios desse patógeno na comunidade.

OBJECTIVES: To investigate the prevalence of Streptococcus pneumoniae (pneumococci) in the nasopharynx of healthy children enrolled in public day-care centers of the municipality of Umuarama, state of Paraná, Brazil. The susceptibility of the pneumococcal strains to antimicrobial agents was also studied. METHODS: Nasopharyngeal specimens from 212 children were collected from April to October 2008. After the specimens were seeded in blood agar and incubated at 37 °C for 24-48 hours, the colonies suspected of belonging to S. pneumoniae were identified using α-hemolysis, optochin sensitivity, and bile solubility test. Penicillin susceptibility was investigated using the disk diffusion and dilution tests. Susceptibility to the other antimicrobial agents indicated for the treatment of pneumococcal infections was investigated using the disk diffusion test. RESULTS: The prevalence of nasopharyngeal pneumococci was 43.4 percent (92/212), with higher rates in children between 2 and 5 years old (p = 0.0005). There was no significant difference between sexes. Intermediate and full resistance to penicillin were found in 34.8 (32/92) and 22.8 percent (21/92) isolates, respectively. Sixty-seven strains (72.8 percent) were resistant to sulfamethoxazole-trimethoprim, eight (8.7 percent) were resistant to erythromycin, and six (6.5 percent) to tetracycline. One strain was resistant to clindamycin (1.1 percent) and another was resistant to chloramphenicol (1.1 percent). All strains were sensitive to levofloxacin, ofloxacin, rifampicin, telithromycin, linezolid, and vancomycin. Nine strains were considered multiresistant because they were resistant to three or more classes of antimicrobial agents. CONCLUSIONS: The present study detected a high prevalence of healthy children colonized with penicillin-resistant S. pneumoniae strains who may be important reservoirs of this pathogen in the community.

Quinolone-resistant Escherichia coli

Quinolones (nalidixic acid - NAL, norfloxacin - NOR, ciprofloxacin - CIP and gatifloxacin - GAT) were tested against Escherichia coli isolated from urine (385 patient samples) by disk diffusion (DD) and agar dilution (AD) methods. Fifty-three samples (13.8 percent) were classified as resistant to at least one of the quinolones tested. CIP and NOR susceptibilities were the same (91.4 percent) and they were similar to GAT (92.7 percent). Susceptibility to NAL, detected by the disk diffusion method, was used to predict susceptibility to NOR, CIP and GAT by the agar dilution method. The sensitivity and specificity of NAL were 100 percent and 95 percent, respectively. Twelve samples were analyzed for mutations in the quinolone resistance-determining region (QRDR) of the gyrA and parC genes. Sequencing of these genes failed to find any mutations in the quinolone-sensitive isolates. However, three mutations were observed in the isolates resistant to all the quinolones tested - two in gyrA and one in parC. A single mutation in gyrA was found in the strains that were resistant to nalidixic acid but fluoroquinolone-sensitive. These findings support the suggestion that NAL could be used as a marker for susceptibility to fluoroquinolones in routine microbiology laboratories. The overall resistance rate to quinolones in the present study was 13.8 percent, which is higher than that observed in other studies carried out in developed countries. Our findings serve as a warning that resistance to this group of antimicrobial agents is increasing.