Etiology and Incidence of positive Microbiological tests in the Department of Pneumology

Abstract

The support of microbiological diagnosis for the management of the lower respiratory tract infections is of great utility. It is known, however, that for a correct therapeutic approach is essential to obtain clinical data and images diagnostic. Sometimes, in fact, to important clinical symptoms can coincide with microbiological results little worth, or the isolation from a sputum of certain bacteria, can be an expression of colonization or trivial contamination.The objective of this work was to evaluate the frequency of bacterial species responsible for respiratory tract infections, through direct (culture) and indirect (serology) methods. Between October 2007 - October 2008, 192 sputum cultures were examined, from the Department of Pneumology and out-patients.The isolation of bacterial strains was performed by seeding samples on the following media (Dasit): Columbia blood Agar (A.) CNA, mannitol salt A., Wurtz lactose A., Sabouraud A., enriched chocolate A. + bacitracin. For serological tests, immunoassays in microplates (Vircell) were used. The data show that of 192 samples deriving from Department of Pneumology, 41 (22%) were positive, while among the out-patient samples, the percentage of positive cultures was 41% (20 positives on the total of 49 samples).The bacteria more frequently isolated in the department of Pneumology, was Pseudomonas aeruginosa (n.8) while in out-patients was Escherichia coli (n.8). Serological tests resulted positive for anti-Mycoplasma pneumoniae antibodies in 3 cases, and for anti-Chlamydia pneumoniae in one case, compared to 53 negative samples. The findings that over 75% of cultures have demonstrated negative results, is suggestive of an origin non-bacterial infections of the lower respiratory tract.Among the bacterial isolates are predominant “opportunistic bacteria” (46%) presumably responsible of nosocomial infections, while in the out-patients are Enterobacteriaceae the prevalent microrganisms isolated.

Keywords

• respiratory tract infections, sputum cultures, Pseudomonas aeruginosa, Escherichia Coli