Early respiratory infection in patients admitted in ICU: microbiological profile and effectiveness of initial therapy

Background

First intention treatment for early acquired respiratory infections diagnosed in an ICU is usually made without micro–biological identification. Microbiological profile is important in supporting therapeutic options.

Objectives

Study of the microbiological profile and effectiveness of first intention antibiotic therapy in early respiratory infections.

Methods

Retrospective clinical study of 385 patients admitted to our ICU, from January to September 2000; selection of those with respiratory infection diagnosed in the first 72 hours of admission. Tracheobronchitis was defined by 'new' purulent bronchial secretions, with fever (> 38.5°C, axilar) and leucocytosis (> 10,000), and pneumonia by the three mentioned criteria plus 'new' pulmonary infiltrate. For these patients we reviewed the microbiologi–cal profile of specimens collected in the first 72 hours and the antimicrobial therapy.

Results

In 105 (27.3%) of the patients admitted it was diagnosed an early respiratory infection: 47 (44.8%) had pneumonia and 58 had (55.2%) traqueobronquitis. A total of 56 organisms were isolated, in 43 patients (41%). 98.2% of the isolations were obtained from tracheobronchial aspiration. Agents involved were: Haemophilus influenzae (39.3%), Staphylococcus aureus MS (23.2%), Streptoccus pneumoniae (19.6%), Klebsiella pneumoniae (1.8%), Moraxella catarrhalis (1.8%), E. coli (3.6%), Proteus mirabilis (1.8%), Enterobactereacea (1.8%), Pseudomonas aeruginosa (3.6%), Serratia marcenses (1.8%) and Staphylococcus aureus MR (1.8%). The patients in whom we isolate the Pseudomonas aeruginosa, Serratia marcenses and Staphylococcus aureus MR were already hospitalised and had comorbidities. First intention treatment was in the vast majority amoxicilin + clavulanate (72 patients — 68.6%). Initial therapy was changed according to antibiogram in 5 patients and in 18 patients (17.1%) it was necessary to change the therapy without microbiological guidance.

Conclusions

Early respiratory infection is a frequent diagnosis in our ICU (27.3%). The microbiological profile in our patients shows, in 93% of the cases, organisms usually acquired in the community. Amoxicilin and clavulanate as first intention therapy appeared to be a good option (it failed only in 7% of the patients in whom it was used), and according to our microbiological profile it seems to be a good choice.