THE BACTERIOLOGY OF OBSTRUCTIVE PNEUMONITIS - A PROSPECTIVE-STUDY USING ULTRASOUND-GUIDED TRANSTHORACIC NEEDLE ASPIRATION

Obstructive pneumonitis, the opacity that develops distal to an obstru cting endobronchial lesion or external compression, is actually a comb ination of atelectasis, bronchiectasis with mucus plugging, and true p arenchymal inflammation. In the majority of cases, it is usually not p ossible to determine whether infection is present or not from the radi ographic findings alone. The aim of this study was to evaluate the bac teriology of obstructive pneumonitis and the influence of this result on the treatment of patients. From March 1992 to February 1993, 26 con secutive patients (20 men and six women) with obstructive pneumonitis were investigated. The obstructive pneumonitis had been caused by mali gnant tumors in 24 and benign lesions in two. Chest ultrasound (US) an d US-guided percutaneous transthoracic aspirations were undergone to o btain specimens for microbiologic examination. Microorganisms were iso lated from seven of nine febrile patients and two of 17 nonfebrile pat ients. A total of 16 bacterial strains are detected in obstructive pne umonitis (Pseudomonas aeruginosa, Klebsiella pneumoniae, viridant stre ptococci, Bacteroides fragilis, two Peptostreptococcus species, Mycoba cterium tuberculosis, Pseudomonas maltophilia, Streptococcus sanguis, Staphylococcus aureus, Bacteroides thetaiotamomicrons, Bacteroides int ermedius, Bacteroides species, Veillonella species, aerobic gram-posit ive bacilli, and Escherichia coli). In five cases the isolates were mo nobacteriae, and in the remaining four cases, cultures yielded more th an one bacteria. The results of aspirate cultures led to changes in th e initial antibiotic trial in seven of nine patients, and fever subsid ed thereafter. Pneumothorax occurred in one case as the sole complicat ion. The pathogen causing obstructive pneumonitis is very heterogeneou s, and polymicrobial infection is common. Chest US and US-guided percu taneous transthoracic aspiration is helpful in identifying potential p athogens and selecting effective therapy for patients with obstructive pneumonitis.