Comparison of Two Culture Methods for Detection of Tobramycin-Resistant Gram-Negative Organisms in the Sputum of Patients with Cystic Fibrosis
AUTOR(ES)
Van Dalfsen, Jill M.
FONTE
American Society for Microbiology
RESUMO
A culture method utilizing quantitative plating on antibiotic-containing media has been proposed as a technique for the detection of tobramycin-resistant organisms that is more sensitive than standard methods. Typical sputum culture methods quantitate the relative amounts of each distinct morphotype, followed by antibiotic susceptibility testing of a single colony of each morphotype. Sputum specimens from 240 cystic fibrosis patients were homogenized, serially diluted, and processed in parallel by the standard method (MacConkey agar and OF basal medium with agar, polymyxin, bacitracin, and lactose) and by plating on antibiotic-containing media (MacConkey agar with tobramycin added at 25 μg/ml [MAC-25] and 100 μg/ml [MAC-100]). MICs of tobramycin were determined for all Pseudomonas aeruginosa isolates by broth microdilution. Growth of P. aeruginosa on MAC-25 was considered to be equivalent to a tobramycin MIC of ≥16 μg/ml, and growth on MAC-100 was considered to be equivalent to a tobramycin MIC of ≥128 μg/ml. Analysis of method-specific detection rates showed that tobramycin-containing medium was more sensitive than the standard method for the detection of tobramycin-resistant P. aeruginosa, Stenotrophomonas maltophilia, and Achromobacter xylosoxidans but was less sensitive for the detection of Burkholderia cepacia than the standard method. When MICs for P. aeruginosa that grew on tobramycin-containing medium were tested by broth microdilution, the MICs for 28 of 121 strains (23%) growing on MAC-25 and 22 of 56 strains (39%) growing on MAC-100 were MICs <16 and <128 μg/ml, respectively. Addition of a tobramycin-containing MacConkey plate to the routine media for sputum culture may provide additional, clinically relevant microbiologic data.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=120123Documentos Relacionados
- Defective cellular immunity to gram-negative bacteria in cystic fibrosis patients.
- Home-use nebulizers: a potential primary source of Burkholderia cepacia and other colistin-resistant, gram-negative bacteria in patients with cystic fibrosis.
- Concordance of endotoxemia with gram-negative bacteremia in patients with gram-negative sepsis: a meta-analysis.
- Comparison of Culture and PCR for Detection of Burkholderia cepacia in Sputum Samples of Patients with Cystic Fibrosis
- Activity of Azlocillin and Mezlocillin Against Gram-Negative Organisms: Comparison with Other Penicillins