Antimicrobial susceptibility of streptococcal strains of mitis group isolated from respiratory tract infections in paediatric patients

Abstract number: R2180

Objective: The mitis group belongs to the oral streptococci, which are commensal bacteria, but sometimes can be involved in the aetiology of serious infections. The aim of the present study was to investigate the antimicrobial susceptibility of 39 mitis group streptococcal strains belonging to: Streptococcus oralis, S. mitis and S. sanguinis species (the last one being included by R. R. Facklam in the sanguinis group), which were isolated from different respiratory tract infections (pneumonia, sepsis of pulmonary origin, peritonsillar abscess, rhinosinusitis, otitis media etc.) in paediatric patients from three hospitals in Bucharest, in 2009.

Methods: The susceptibility of the isolates was tested against: penicillin G (PG), ampicillin (AM), cefotaxime (CT), erythromycin (EM), clindamycin (CM), tetracycline (TC), levofloxacin (LE), linezolid (LZ) and vancomycin (VA), using the Etest (AB Biodisk, Sweden).

Results: The ranges of the minimum inhibitory concentrations were: 0.047–32 mg/l for PG, 0.032–32 mg/l for AM, 0.032–24 mg/l for CT, 0.016–256 mg/l for EM, 0.016–64 mg/l for CM, 0.25–48 mg/l for TC, 0.19–1 mg/l for LE, 0.064–0.75 mg/l for LZ and 0.5–1 mg/l for VA. About half of the isolates were resistant to the three b-lactam antibiotics. Only a quarter of the strains were susceptible to EM, while more than 90% and about 60% were sensitive to CM and TC, respectively. Resistance to: PG, AM, CT, EM and TC was found among the strains belonging to the three species, while all S. mitis isolates were susceptible to CM.

Conclusion: Since there is a great concern regarding the increased number of oral streptococci resistant to b-lactam antibiotics or multidrug-resistant, it is necessary to test the sensitivity of the isolates of clinical importance, especially to the commonly used antibiotics. LE, LZ and VA were the only antimicrobial agents fully active against the mitis group isolates investigated in the present work, which was a study supported by the project ID_2652 no. 1136/12.01.2009 from the Exploratory Research Projects of the National University Research Council and the Executive Agency for Higher Education and Research Funding from Romania.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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