No abstract

We studied the spectrum of clinical disease in 99 patients with nosocomial Pseudomonas maltophilia isolates at the University of Virginia Hospital from 1981 through 1984. The annual rate of isolation increased from 7.1 to 14.1 per 10,000 patient discharges. A crude mortality rate of 43% was docuniented in all patients from whom the organism was cultured, and the data include 12 patients with nosocomial bacteremia (four deaths). Risk factors associated with death for patients having a P. maltophilia isolate included the following: requirement for care in any intensive care unit during hospitalization (P = 0.0001), patient age over 40 years (P = 0.002), and a pulmonary source for the P. maltophilia isolate (P = 0.003). All P. maltophilia isolates were susceptible to trimethoprim-sulfamethoxazole, 60% of the isolates were resistant to all aminoglycosides (amikacin, tobramycin, and gentamicin), and more than 75% of the isolates were resistant to all I-lactam antibiotics. The antibiotic susceptibility pattern allows for a niche exploitable in the hospital microbial environment by an organism with a marked associated mortality.

Over a 7-year period (1978-1984) the authors studied the rates of nosocomial bloodstream infections in acute-care hospitals participating in a statewide surveillance network in Virginia. A total of 4,617 hospital-acquired bloodstream infections were documented among 1,807,989 patients at risk for an overall rate of 25.5 cases per 10,000 patient admissions/discharges (annual range = 22.1 to 30.7). Compliance of reporting for Virginia hospitals averaged 58% (1 to 5 monthly reports in a study year), and 39% (greater than or equal to 6 monthly reports annually). Significant changes in bloodstream infection rates (cases per 10,000 patient admissions/discharges) due to specific pathogens included the following: coagulase-negative staphylococci increased from a rate of 1.3 to 4.5 (P = .0003), and those due to all gram-positive cocci increased from a rate of 7.5 to 11.4 (P = .03). Candida species increased from a rate of 0.1 to 1.5 (P = .005). The data show a continuing rise of nosocomial Candida BSI and clearly document the re-emergence of gram-positive cocci as major nosocomial bloodstream pathogens.

Various sources of Pseudomonas paucimobilis bacterial infections have been documented. We report the third human case of bloodstream infection due to P. paucimobilis and review the literature in English regarding community-acquired and nosocomial infection due to this bacterium. Biochemical and genetic characteristics supporting the pathogenic potential of P. paucimobilis are presented, and the antibiotic susceptibility profile of the organism is summarized. Pseudomonas paucimobilis, formerly categorized as CDC group IIk, biotype 1, was accorded taxonomic status in 1977 (10). It is a gram-negative, aerobic, motile bacterium with a polar flagellum. The appellation paucimobilis derived from the observation that few cells are actively motile in broth culture, thereby making bacterial motility a difficult characteristic to demonstrate. It can be misidentified as a Flavobacterium species because of its production of a yellow pigment that has been biochemically characterized as a carotenoid (12). P. paucimobilis demonstrates a diverse nutritional substrate spectrum (6) and grows at 37°C, but not at 5 or 42°C, with optimal growth occurring at 30°C (16). Recent reports document the heterogeneity of fatty acid composition (4) and DNA homology (15) between P. paucimobilis and the bacteria constituting group Ilk, biotype 2 (Flavobacterium species). Such findings underscore the limited taxonomic proximity of these organisms. The dissimilarity between P. paucimobilis and other pseudomonads was highlighted by Smalley and Ourth (22), who used crude