Streptococcus pneumoniae: sensibilidade a penicilina e moxifloxacina

Abstract

Objective: To determine the minimum inhibitory concentrations (MICs) of parenteral penicillin and moxifloxacin against Streptococcus pneumoniae strains isolated at a hospital center. Methods: In-vitro, prospective study involving 100 S. pneumoniae isolates collected from patients who had been treated, between October of 2008 and July of 2010, at the Hospital das Clínicas complex of the University of São Paulo School of Medicine, located in the city of São Paulo, Brazil. The isolates were obtained from respiratory tract cultures or blood samples unrelated to meningeal infections, and they were tested for penicillin and moxifloxacin susceptibility by E-test. The MIC category interpretations were based on updated standards. Results: All isolates were fully susceptible to parenteral penicillin (MIC ≤ 2 µg/mL), and, consequently, they were also susceptible to amoxicillin, ampicillin, third/fourth generation cephalosporins, and ertapenem. Of the S. pneumoniae strains, 99% were also susceptible to moxifloxacin, and only one strain showed an MIC = 1.5 µg/mL (intermediate). Conclusions: Our results showed high susceptibility rates to parenteral penicillin and moxifloxacin among S. pneumoniae isolates unrelated to meningitis, which differs from international reports. Reports on penicillin resistance should be based on updated breakpoints for non-meningitis isolates in order to guide the selection of an antimicrobial therapy and to improve the prediction of the clinical outcomes. Os isolados foram obtidos de culturas do trato respiratório e de amostras de sangue não relacionadas a infecções meníngeas e foram testados quanto à suscetibilidade a penicilina e moxifloxacina por E-test. As interpretações categóricas de CIM foram baseadas em padrões atualizados. Resultados: Todos os isolados foram suscetíveis a penicilina parenteral (CIM ≤ 2 µg/mL) e, consequentemente, eram também suscetíveis a amoxicilina, ampicilina, cefalosporinas de terceira e quarta geração e ertapenem. Quanto à moxifloxacina, 99% das cepas de S. pneumoniae também foram suscetíveis, e somente uma teve CIM = 1,5 µg/mL (intermediário). Conclusões: Nossos resultados mostraram altas taxas de sensibilidade a penicilina parenteral e moxifloxacin nos isolados de S. pneumoniae não relacionados a meningite, o que difere de relatos internacionais. Relatos sobre resistência a penicilina devem ser baseados em pontos de corte atualizados para isolados não relacionados a meningite a fim de guiar a escolha terapêutica antimicrobiana e melhorar a predição dos desfechos clínicos. MethodsThis was as an in-vitro, prospective study involving 100 S. pneumoniae isolates collected from patients (one sample per patient) who had been treated, between October of 2008 and July of 2010, at one of the ten hospitals that compose the Hospital das Clínicas complex of the University of São Paulo School of Medicine, located in the city of São Paulo, Brazil. The isolates were obtained from respiratory tract cultures or blood samples that were unrelated to meningeal infections (i.e.,...

Serotypes and Genotypes of Invasive Streptococcus pneumoniae Before and After PCV10 Implementation in Southern Brazil

“…The prevalence of penicillin resistance seems to be variable, with reported rates as low as 0% [53] , [54] , [55] and as high as 27.9% [25] , [54] in Brazil. It is important to point out that previously published rates used the 2008 CLSI breakpoints to determine β-lactams susceptibility, and in this study, penicillin MICs ≥4 µg/mL were not observed.…”

Surgical Wound Infection by Streptococcus pneumoniae After a Cat-Scratch Disease

“…3 This communication then describes what appears as a previously unreported picture of pneumococcal pathology, and is the first to include pneumococci within the spectrum of wound infecting pathogens. 4…”

“…S pneumoniae resistance to antibiotics has spread all over the world. 1,4 Penicillin-resistant strains structurally modify PBPs (penicillin-binding proteins). 4 Macrolide-resistant isolates express an ermB - or mefA -related 23S methylase (conferring resistance to 14-, 15-, and 16-membered-ring macrolides, lincosamides, and streptogramin B [MLS B phenotype]) or efflux pumps (extruding 14- and 15-membered-ring macrolides only).…”

“…1,4 Penicillin-resistant strains structurally modify PBPs (penicillin-binding proteins). 4 Macrolide-resistant isolates express an ermB - or mefA -related 23S methylase (conferring resistance to 14-, 15-, and 16-membered-ring macrolides, lincosamides, and streptogramin B [MLS B phenotype]) or efflux pumps (extruding 14- and 15-membered-ring macrolides only). 1 Fluoroquinolone resistance instead is due to mutations in the QRDRs (quinolone resistance determining regions) of parC and gyrA genes, encoding the A and B subunits of DNA gyrase and topoisomerase IV.…”

“…1 Fluoroquinolone resistance instead is due to mutations in the QRDRs (quinolone resistance determining regions) of parC and gyrA genes, encoding the A and B subunits of DNA gyrase and topoisomerase IV. 4 Moxifloxacin has however a greater activity against pneumococci (among fluoroquinolones) as it shows a higher affinity for DNA gyrase than do older compounds of the group; also, it is bulkier and less hydrophilic and exhibits a decreased affinity for the efflux mechanism. 4…”