New susceptibility breakpoints in antimicrobial resistance rates of invasive pneumococcal strains

Abstract

Objective: To evaluate the impact of new penicillin susceptibility breakpoints on resistance rates of pneumococcal strains collected from children with pneumonia.Methods: Pneumococcal strains collected from patients admitted with pneumonia were isolated at the clinical analysis lab of Hospital de Clínicas de Uberlândia, Uberlândia, Brazil, and sent to Instituto Adolfo Lutz, São Paulo, Brazil, for further identification, serotyping and determination of antimicrobial susceptibility.Results: From April 1999 to December 2008, 330 strains of pneumococcus were sent to Instituto Adolfo Lutz; of these, 195 (59%) were collected from patients with pneumonia. One hundred strains collected from patients ≤ 12 years old were analyzed. The patients' age ranged from 1 to 12.6 years old (with mean age of 2.4 and median of 1.7 years). Forty-seven patients were male. The strains were isolated from blood (42%) and pleural fluid (58%). There were 35 oxacillin-resistant strains: according to the criteria defined by the Clinical and Laboratory Standards Institute (CLSI) in 2007 [minimum inhibitory concentration (MIC) ≤ 0.06 µg/mL for susceptibility (S), 0.12 to 1 µg/mL for intermediate resistance (IR), and ≥ 2 µg/mL for full resistance (FR)], 22 strains had IR and 11 strains had FR. According to the current breakpoints defined by the CLSI in 2008 (≤ 2 µg/mL for S, 4 µg/mL for IR and ≥ 8 µg/mL for FR), only one strain had IR to penicillin. There was resistance to co-trimoxazole (80%), tetracycline (21%), erythromycin (13%), clindamycin (13%), and ceftriaxone (one strain simultaneously resistant to penicillin). Conclusions:When the new breakpoints for in vitro susceptibility were applied, penicillin resistance rates dropped 97%, from 33 to 1%. ≤ 0,06 µg/mL para sensibilidade (S), 0,12 a 1 µg/mL para resistência intermediária (RI) e ≥ 2 µg/mL para resistência plena (RP)], 22 cepas apresentaram RI e 11, RP para penicilina. De acordo com os critérios atuais do CLSI de 2008 (≤ 2 µg/mL para S, 4 µg/mL para RI e ≥ 8 µg/mL para RP) apenas uma cepa confirmou RI à penicilina. Detectouse resistência a cotrimoxazol (80%), tetraciclina (21%), eritromicina (13%), clindamicina (13%) e ceftriaxona (uma cepa, simultaneamente resistente a penicilina). J Pediatr (Rio J) Conclusões:Com a aplicação dos novos pontos de corte para sensibilidade in vitro, as taxas de resistência a penicilina caíram 97%, de 33 para 1%. J Pediatr (Rio J)

Fatores associados às complicações em crianças pré-escolares com pneumonia adquirida na comunidade

“…However, there is a concern about the incorrect indication of penicillins in viral processes; this is a commonplace practice in emergency rooms and can lead to increased bacterial resistance to the antibiotics that are widely used in pediatric patients. (30) In summary, the present study showed that the development of complications in children with CAP is directly associated with biological variables such as patient history, previous use the hypothesis that the study population had good nutritional status and easy access to health care, including clinical follow-up and nutritional guidance in the first year of life.…”

Outcome of children hospitalized with community-acquired pneumonia treated with aqueous penicillin G

“…As the CARIBE Study concluded that there is no association between penicillin G therapeutic failure and pneumococcal minimal inhibitory concentration up to 4 µg/mL,22 pediatricians are probably confident about the success of penicillin G. By studying the pharmacokinetics of 200,000 IU/kg/day of penicillin G in children with CAP, serum penicillin G concentrations were >4 µg/mL for >40% of the interdose interval,23 which predicts therapeutic success in treating pulmonary infections caused by pneumococcal strains with minimal inhibitory concentration up to 4 µg/mL 24. In Brazil, up to the present, the highest minimal inhibitory concentration described for pneumococcal strains is 4 µg/mL, which is rare 25. …”

Análise das cepas de Streptococcus pneumoniae causadores de pneumonia invasiva: sorotipos e sensibilidade aos antimicrobianos

“…Penicillin resistance rates in 100 S. pneumoniae strains isolated from children aged 12 or younger with a diagnosis of pneumonia declined from 33 to 1% upon adoption of new CLSI breakpoints. 21 This wealth of data shows that penicillin antibiotics are still an excellent therapeutic option for treatment of pneumococcal pneumonia.…”