Pseudomonas aeruginosa bacteraemia. Is pancreatobiliary disease a risk factor?

OBJECTIVE

To review changes in the epidemiology, course, and outcome of bacteraemia caused by Pseudomonas aeruginosa.

DESIGN AND SETTING

A retrospective, descriptive study of consecutive cases of P. aeruginosa bacteraemia occurring at a university teaching hospital.

PATIENTS AND METHODS

Between January 1980 and December 1989, 164 patients were admitted to Westmead Hospital with P. aeruginosa bacteraemia. Patients in whom there was no clinical evidence of sepsis were excluded from analysis leaving a cohort of 152 patients. Hospital records were reviewed and details of demography, clinical features, therapy, and outcome were recorded.

RESULTS

One hundred and fifty-five episodes of P. aeruginosa bacteraemia were recorded at an average rate of 0.39 per 1000 admissions per year. The respiratory and pancreatobiliary tracts were the most common sources of the bacteraemia. Pancreatobiliary disease, independent of an underlying malignancy or immunosuppression, emerged as a previously undescribed risk factor for pseudomonal bacteraemia (incidence of 3.0 episodes per 1000 hospital admissions for patients with this disease). The crude mortality rate was 52%; 35% was attributable to pseudomonal bacteraemia. Factors identified as being independently associated with an increased mortality included hypotension, age of 60 years or older, and the presence of an underlying malignancy. Combination therapy with an antipseudomonal penicillin and an aminoglycoside confers a significant survival advantage independent of underlying neutropenia.

CONCLUSIONS

Bacteraemia caused by P. aeruginosa remains an important cause of morbidity and mortality. Pancreatobiliary disease represents a new risk factor for P. aeruginosa bacteraemia, independent of an underlying malignancy or immunosuppression. It may be prudent to consider P. aeruginosa as a cause of sepsis in these circumstances, especially if there has been instrumentation of the biliary tree. Hypotension, age of 60 years or older, and the presence of an underlying malignancy were independently associated with significantly increased mortality. Appropriate antibiotic therapy consisting of an antipseudomonal beta-lactam in addition to an aminoglycoside resulted in a significant decrease in mortality compared with the use of an aminoglycoside alone, not only in the study population as a whole, but also in patients without neutropenia.