Mycobacterium mucogenicum from the Hickman line of an immunocompromised patient.

Gram stain of a positive blood culture is the clinician's first indication of a possible causative infective organism and a guide to suitable antimicrobial therapy prior to cultural and phenotypic identification with susceptibility test results. Occasionally interpretation of a Gram stain can be difficult; if there is a low bacterial load, no organisms may be seen. Such a case is reported, where a positive blood culture taken from the Hickman line of an immunocompromised patient flagged as positive at 5 days' incubation, but no organisms were seen on Gram film. On subculture, a slow growing Gram-positive bacillus was isolated which was initially misidentified and reported as a "diphtheroid" species. The actual identity of this organism and further isolates was later elucidated as Mycobacterium mucogenicum, a rapidly growing non-tuberculous mycobacterium.

Hospital-acquired listeriosis.

We report four cases of listeriosis that occurred over a two-month period in north east England. Due to the apparent nosocomial acquisition of infection and the clustering of cases in time and place, extended epidemiological investigation was performed and the outbreak was traced to a caterer who was providing sandwiches for hospital shops. We discuss the difficulties in preventing food-borne listeriosis in the hospital setting.

Cross infection on a combined paediatric plastic surgery and burns unit: a clinical and microbiological audit.

To try and determine any presence of cross-infection between patients, prospective screening of 226 consecutive admissions on our burns unit was performed by taking nose, throat and wound swabs. Infected wounds were also swabbed and a correlation was sought between the organisms cultured on screening swabs and those responsible for infection. We did not find any evidence of cross- infection occurring between the burns patients and the other categories of patients on the ward. Screening swabs were useful in detecting carriers, who were found to be more of a risk to themselves than to other patients on the unit.

Non-tuberculous mycobacterial infection in children with cancer.

Reported here is the clinical presentation and management of patients with rapidly growing non-tuberculous mycobacterial infection diagnosed in a paediatric oncology unit. A retrospective analysis that correlated patient isolates with the children's cancer registry revealed two cases of non-tuberculous mycobacterial infection; both had been observed within the last 6 years and were due to Mycobacterium chelonae. The first case was line-associated and the second was a disseminated infection. In both cases the patients were lymphopenic and had had indwelling vascular catheters. Neither patient was neutropenic. The literature on mycobacterial infection in children with cancer is also reviewed.

Investigation of gaseous ozone for MRSA decontamination of hospital side-rooms.

A domestic, gaseous ozone generator was investigated for use in the decontamination of hospital side-rooms that have housed patients colonized with methicillin-resistant Staphylococcus aureus (MRSA). Three models of bacterial contamination were used. These were exposed to ozone generation in a standard hospital side-room for 4 and 7 h. A methicillin-sensitive and a methicillin-resistant strain of S. aureus were compared. Ozone concentrations of 0.14 ppm were reached, levels which are sufficient to cause mild pulmonary toxicity. Bacterial counts were reduced in the vicinity of the gas generator in most instances, but the effect elsewhere in the room was, at best, limited. MRSA appeared more resistant to the effects of ozone than methicillin-sensitive S. aureus. We conclude that the device tested would be inadequate for the decontamination of such hospital side-rooms.

The fate of glucose in strains S288C and S173-6B of the yeast Saccharomyces cerevisiae.

Intracellular metabolic flux has been investigated in two strains of Saccharomyces cerevisiae grown into stationary phase under both glucose-repressed and glucose-derepressed conditions. By employing a variety of simple methodologies (manometry, enzymatic analysis and colorimetric analysis) we have been able to identify and quantitate carbon flow from glucose without the need for isotopically labelled substrate. We can account for 88-98% (depending on strain and growth conditions) of the carbon products of glucose metabolism under both glycolytic and oxidative conditions as ethanol (27-40%), carbon dioxide (15-26%), acetate (2-3%), glycerol (5-11%), glycogen (5-13%) and trehalose (9-39%).

Ecthyma gangrenosum occurring at sites of iatrogenic trauma in pediatric oncology patients.

We report two cases of ecthyma gangrenosum which occurred at sites of iatrogenic trauma. The first case developed due to metastatic seeding with Pseudomonas aeruginosa during an episode of septicaemia and the second case occurred as a primary skin lesion. Both required prolonged courses of antibiotics and one patient died. The different pathogenic mechanisms and outcomes associated with this condition are discussed.

Effectors of metabolic depression in an estivating pulmonate snail (Helix aspersa): whole animal and in vitro tissue studies.

We have examined metabolic depression in the land snail (Helix aspersa) during estivation, and have developed a tissue model of metabolic depression using an in vitro mantle preparation. The metabolic rate of H. aspersa is depressed by 84% in vivo within 4 weeks of onset of estivation, and this metabolic depression is accompanied by a decrease in haemolymph PO2 and pH, and an increase in haemolymph PCO2. The in vitro mantle preparation has a stable O2 consumption and energy charge, and an energy charge similar to that of mantle in vivo. The in vitro mantle is an O2-conforming tissue, with VO2 varying curvilinearly with PO2. Consequently, we have developed a mathematical method of calculating tissue VO2 at any PO2. These calculations show that under appropriate incubation conditions of pH and PO2, the mantle from estivating animals shows a stable in vitro metabolic depression of 48% compared to mantle from control snails. The extrinsic effects of PO2 and pH account for 70% of the total in vitro metabolic depression of mantle tissue; intrinsic effectors contribute a further 30%.

Non-enteritic aeromonas infections in hospitalized patients.

Aeromonas species were isolated from specimens other than faeces from 59 hospital inpatients over a 15 year period. Of the isolates, 79.7% were regarded as clinically significant, with skin and soft tissues and blood cultures as the commonest sites of infection. Of the isolates, 52.5% were hospital-acquired, and 55.9% of patients had serious underlying disease. Community-acquired infections in previously healthy individuals accounted for only 13.6% of isolates. However unlike many other opportunistic infections, aeromonas infection was not closely associated with prior antibiotic therapy, nor was there a significant increase in the frequency of infection over the study period.

Cutaneous Mycobacterium kansasii infection: case report and review.

A case of cutaneous Mycobacterium kansasii infection is reported, and 28 similar cases are reviewed. Cutaneous infection may resemble sporotrichosis and is often associated with systemic illness, immunosuppression, skin pathology, or contact with contaminated water. Immunosuppressed patients with M. kansasii infection may present with atypical clinical features (such as cellulitis and seroma) and atypical histology (absence of granulomas), which may delay diagnosis and effective treatment. The incidence of disseminated M. kansasii infection, which has a worse prognosis, is higher among immunosuppressed patients. When M. kansasii infection is confined to the skin, the disease is usually indolent. Chemotherapy with a variety of agents, including traditional antituberculous agents as well as erythromycin, minocycline, and doxycycline, has been successful, although in vitro resistance to isoniazid and p-aminosalicylic acid is common. Reducing the dose of corticosteroids may be a beneficial adjunct to therapy for M. kansasii infection.

A multicentre study of the in-vitro activity of cefotaxime, cefuroxime, ceftazidime, ofloxacin and ciprofloxacin against blood and urinary pathogens.

The in-vitro susceptibilities of aerobic bacteria isolated from 1804 blood and 4529 urine specimens collected at nine hospitals in the UK were examined. An agar dilution method was used to determine the MICs of each isolate to three cephalosporins, cefotaxime, cefuroxime and ceftazidime, and to two fluoroquinolones, ofloxacin and ciprofloxacin. Sensitivities were then calculated using British Society for Antimicrobial Chemotherapy recommended breakpoints. Of the cephalosporins tested cefotaxime was the most active against the Enterobacteriaceae. All the systemic staphylococcus isolates collected were sensitive to both cefotaxime and cefuroxime. As expected, ceftazidime was the only cephalosporin active against the Pseudomonas isolates. Both quinolones were highly active against the Enterobacteriaceae and Pseudomonas spp. They also demonstrated good Gram-positive activity, particularly against Staphylococcus aureus and Enterococcus spp.

A method for the determination of the cellular phosphorylation potential and glycolytic intermediates in yeast.

A method is described for rapidly quenching metabolism in yeast and extracting metabolites for analysis. The saponin digitonin is used to permeabilize the yeast cell membrane, in conjunction with perchloric acid (PCA) to quench metabolism and extract metabolites. Using this digitonin-PCA quench and extraction procedure, we have determined ATP concentrations in Saccharomyces cerevisiae in the range 2.89-3.39 mM, [ATP]/[ADP] ratios of 4.5-6.6, and phosphorylation potentials of 48.7-49.9 kJ.mol-1. A direct comparison with the currently accepted freeze/grind PCA/thaw procedure for extraction of yeast cell metabolites shows that essentially the same values are obtained by both techniques. The digitonin-PCA quench extraction method, used in conjunction with automated enzymatic analyses of metabolites, allows rapid extraction and analysis of large numbers of samples and metabolites and hence permits detailed investigations of intermediary metabolism in yeast.