Israel Medical Association Journal

Background: Recent data regarding polymicrobial bacteremia (PMB) are lacking.

Objectives: To characterize risk factors as well as clinical, microbiological, and prognostic patterns of patients with PMB in a modern hospital setting.

Methods: A single center retrospective study including all patients diagnosed with PMB during 2013 was conducted. PMB was defined as two or more organisms cultured from the blood of the same patient within 72 hours. Patients with monomicrobial infections served as controls.

Results: There were 135 episodes (2% of all bacteremia episodes) of true PMB among 123 patients during the study period. Recent invasive procedures (odds ratio [OR] 3.59, 95% confidence interval [95%CI] 1.41–9.12, P = 0.006) and foreign bodies (OR 1.88, 95%CI 1.06–3.33, P = 0.04) were risk factors for PMB when compared with 79 patients with monomicrobial bacteremia. Central-line-associated infections were the most common infection source among patients with PMB (n=34, 28%). Enterobacteriaceae were the most commonly implicated pathogen (n=95, 77%). Non-fermenting Gram-negative bacilli were significantly more common than previously reported (n=55, 45%). Although crude 30-day mortality was higher (48% vs. 33%) in PMB patients, adjusted mortality was comparable in the two groups.

Conclusions: PMB rate in our cohort was considerably lower than in previous reports. Central-line-associated infections were more common than classic PMB sources. Mortality remained high. Strategies for early identification and better care for these patients should be pursued.

The pulmonary microbiology is a dominant element in cystic fibrosis and the main cause of death. Contemporary consensus accords an exclusive role in this to a single microorganism, Pseudomonas aeruginosa. The evidence convincingly shows that the microbiology consists of a multiplicity of species living in perpetual interaction and in a variety of forms – planktonic, sessile, anaerobic – and in organized communities as microcosms, biofilms and ecosystem. This compound microbiology, the essence of the pulmonary disease, is of necessity exposed to constant influence both from without (the air) and within (via the blood), leading to a perpetual state of flux with consequent impact on the clinical course. It is perhaps significant that to date, most or all microbiologic studies were probably conducted, classically, with inert instruments (glass? plastic?), whereas in real life the CF[1] microbiology lives in “test-tubes” of live mucosa with which it maintains a permanent “cross-talk.” The difference to microbial life between these two media may well be very important. It therefore justifies study and may be far-reaching in its effect. There is persuasive argument to strive for a novel holistic view of the totality of the complex microbiology of CF, and to initiate fresh concepts, strategies and methods.