Colonization of human wounds by Escherichia vulneris and Escherichia hermannii.

In this report we present clinical descriptions of 12 Hawaiian patients from whom Escherichia vulneris or E. hermannii strains were isolated. All but two patients had soft-tissue infections with multiple bacteria, particularly Staphylococcus aureus. The other two had purulent conjunctivitis associated with S. aureus and infected malignant peritonitis with multiple organisms, respectively. In none of the cases were the Escherichia spp. found in abundant quantities or considered pathogenic. In preliminary animal pathogenicity studies, 12 strains each of E. vulneris and E. hermannii failed to cause serious symptoms in 4-week-old mice when 10(7) cells were injected intraperitoneally. When 10(6) cells were used, none of these bacterial strains injected into mouse soft tissue was capable of producing persistent wound infections. Susceptibility studies of 40 strains of these bacteria to 20 different antimicrobial agents showed that they were susceptible to third-generation cephalosporins as well as to most other cephalosporins, aminoglycosides, trimethoprim, and sulfamethoxazole-trimethoprim; these strains were only marginally susceptible or resistant to penicillin, tetracycline, chloramphenicol, and nitrofurantoin.

Aeromonas hydrophila and Plesiomonas shigelloides as causes of intestinal infections.

Infections due to Aeromonas hydrophila and Plesiomonas shigelloides in immuno-compromised hosts have been well documented, but the role of these organisms in causing gastrointestinal disease in healthy persons is controversial. Despite difficulties in characterizing the exotoxins produced by Aeromonas species, there is accumulating evidence that these bacteria are capable of causing usually mild, self-limited diarrheal disease in previously healthy adults. Some pediatric patients may have protracted dysenteric symptoms. P. shigelloides, an organism closely related to Aeromonas species, may also cause diarrhea in the healthy host, but no exotoxins have yet been identified by the assays used to identify other bacterial enterotoxins. Replacement of fluid and electrolytes is the basis of treatment, and antimicrobial agents should be reserved for patients with chronic or serious illness, or for those at particular risk of serious illness (hepatobiliary disease, septicemia, neoplasms).

Polymicrobial bacteremia caused by Ewingella americana (family Enterobacteriaceae) and an unusual Pseudomonas species.

Ewingella americana and a Pseudomonas species were isolated from three sets of blood cultures from a 41-year-old patient after coronary bypass surgery. This is the first well-described case of bacteremia due to E. americana. Based on data from 31 strains, a detailed description of E. americana is given.

Hospital outbreaks caused by Pseudomonas aeruginosa: importance of serogroup O11.

Suspected outbreaks caused by pseudomonas aeruginosa in 19 hospitals and two motels were studied. On the basis of epidemiological analysis, serological typing, and antibiotic resistance patterns, 17 were classified as single-strain outbreaks. Six were classified as common-source outbreaks: of these, three were caused by contaminated urological instruments or solutions, two involved bathing in contaminated whirlpools, and one was caused by contaminated lens prostheses implanted during eye surgery. The ability of P. aeruginosa to survive or grow in wet environments was important in each of these six outbreaks. Eight outbreaks were classified as cross-infection. Two involved the urinary tract and were caused by antibiotic-resistant strains. Six involved the respiratory tract, but only one was caused by an antibiotic-resistant strain. In 2 of the 17 single-strain outbreaks, the exact mode of transmission could not be determined. One was an outbreak of pseudobacteremia in which patient blood cultures were contaminated with a single strain, presumably during collection of specimens or culture processing, P. aeruginosa serogroup O11 caused 9 of 17 (53%) single-strain outbreaks, a surprising finding since this serogroup represents only about 8% of endemic hospital isolates of this species. Serotyping was very useful in epidemiological analysis, but antibiotic susceptibility patterns were less useful.

Epidemiology of Pseudomonas aeruginosa in a general hospital: a four-year study.

A retrospective study was done to determine the epidemiology of infection and/or colonization due to Pseudomonas aeruginosa in a Brazilian general hospital. In 1966, 1968, and 1969, there were only two instances where probable cross-contamination was shown; the remaining isolates were unrelated. In late 1971 the hospital experienced a marked increase in P. aeruginosa isolation. Contaminated dextrose solutions used in the infant feeding were the apparent cause of the problem which occurred in the premature and special care nurseries. A contaminated oxygen humidifying bottle was the source of a different outbreak in surgery. There was also evidence in four instances that cross-infection and/or contamination had occurred. Pyocin and serological typing revealed that many strains were involved and led to a clear understanding of the complex epidemiological relationships among all the strains.

Aldohexuronic acid catabolism by a soil Aeromonas.

Bacteria which utilize mannuronic acid as an energy source were isolated from nature. One of the organisms, identified as a member of the genus Aeromonas, used glucuronate, galacturonate, and mannuronate as the sole source of carbon and energy. Glucuronate- and galacturonate-grown resting cells oxidized both glucuronate and galacturonate rapidly, but mannuronate slowly. Mannuronate-grown cells oxidized all three rapidly, with the rate of mannuronate utilization somewhat lower. Cell-free extracts from glucuronate-, galacturonate-, and mannuronate-grown Aeromonas C11-2B contained glucuronate and galacturonate isomerases, fructuronate, tagaturonate, and mannuronate reductases, and mannonate and altronate dehydratases, with the exception of glucuronate-grown cells which lacked altronate dehydratase. Thus, the pathway for glucuronate and galacturonate catabolism for Aeromonas was identical to Escherichia coli. Glucuronate and galacturonate were isomerized to d-fructuronate and d-tagaturonate which were then reduced by reduced nicotinamide adenine dinucleotide to d-mannonate and d-altronate, respectively. The hexonic acids were dehydrated to 2-keto-3-deoxy gluconate which was phosphorylated by adenosine triphosphate to 2-keto-3-deoxy-6-phospho gluconate. The latter was then cleaved to pyruvate and glyceraldehyde-3-phosphate. Mannuronate was reduced directly to d-mannonate by a reduced nicotinamide adenine dinucleotide phosphate-linked oxidoreductase. d-Mannonate was then further broken down as in the glucuronate pathway. The mannuronate reducing enzyme, for which the name d-mannonate:nicotinamide adenine dinucleotide (phosphate) oxidoreductase (d-mannuronate-forming) was proposed, was shown to be distinct from altronate and mannoate oxidoreductases. This is the first report of a bacterial oxidoreductase which reduces an aldohexuronic acid to a hexonic acid. The enzyme should prove to be a useful analytical tool for determining mannuronate in the presence of other uronic acids.