RELATION BETWEEN BETA-LACTAMASE-PRODUCING BACTERIA AND PATIENT CHARACTERISTICS IN CHROMIC OBSTRUCTIVE PULMONARY-DISEASE (COPD)

Background - In addition to bronchodilator and anti-inflammatory thera py, exacerbations in patients with chronic obstructive pulmonary disea se (COPD) are often treated with antibiotics. Haemophilus influenzae a nd Moraxella (Branhamella) catarrhalis, two important respiratory path ogens, may produce beta-lactamase which makes them resistant to ampici llin. Surveillance studies conducted in various countries have shown a n increasing incidence of these beta-lactamase producing bacteria. Alt hough this may simply be a consequence of the increasing use of antibi otics, it is possible that other factors are important. A study was un dertaken to investigate whether clinical factors are related to the pr esence of beta-lactamase forming bacteria in the sputum of patients wi th COPD. Methods - One hundred patients with COPD aged over 40 years w ere sequentially selected from an outpatient clinic on the basis of sp utum culture results. Fifty had beta-lactamase positive (beta L +) and 50 had beta-lactamase negative (beta L +) bacteria in their sputum. P atients were included only if sputum culture results yielded one patho gen. The files of these patients were investigated for possible causat ive factors present during the two preceding years. Results - Both gro ups were almost identical in terms of lung function, maintenance medic ation, and smoking history. The total number of antibiotic courses in the beta L + group was higher, as were individual courses of cephalosp orins, tetracyclines, and macrolides. The number of patients admitted to hospital was higher in the beta L + group, but admissions were of e qual duration in both groups. Patients admitted to hospital had poorer lung function. Risk factors for beta-lactamase producing bacteria wer e identified by logistic regression analysis which revealed an odds ra tio for one course of antibiotics of 1.15 (95% CI 1.04 to 1.28). Concl usions - An increased number of antibiotic courses is related to a hig her incidence of beta-lactamase producing bacteria and more patients h ad hospital admissions in the beta L + group. beta-lactamase stable an tibiotics were used more frequently in the beta L + group, probably be cause prescribing was adapted to the presence of beta-lactamase produc ing bacteria. No other differences were found between the beta L + and beta L - groups.