Neutropenic enterocolitis due to Clostridium septicum infection.

Three cases of neutropenic enterocolitis are described. This unusual condition occurs almost exclusively in neutropenic patients and has a fulminating course which is almost invariably fatal without surgical intervention. The lesion is centered on the caecum and hitherto its pathogenesis has been unclear, partly because most studies have been performed on material obtained at necropsy. In these three patients, all of whom were treated surgically, Clostridium septicum was identified by specific immunofluorescence in the bowel wall of the resected specimens. Two patients also had C septicum septicaemia. Various forms of mucosal damage can be identified which predispose towards invasion of the bowel wall by this organism. These cases provide further confirmation of a primary role for C septicum in the pathogenesis of neutropenic enterocolitis.

Clostridium difficile in haematological malignancy.

Twenty patients with haematological malignancies who developed Clostridium difficile bowel infection or colonisation are described. All isolates of C difficile were toxigenic in vitro and faecal cytotoxin (toxin B) was detected in 20/26 episodes. Ten of 20 episodes with detectable faecal cytotoxin were associated with typical antibiotic associated diarrhoea. In the other 10 episodes (nine patients), there was a severe unusual illness which was associated with detection of C difficile. The unusual features of the illness were pronounced jaundice (total bilirubin greater than or equal to 44 mumol/l), abdominal pain and distension, and initial constipation followed either by diarrhoea or by large bowel stasis. Four of these patients died within seven days. Bacteraemia was often a presenting feature in neutropenic patients subsequently shown to have C difficile. This was not the case in non-neutropenic patients. Bacteraemia was commonly polymicrobial and in two cases C difficile was isolated from blood culture. The clinical implications of recognition of this atypical C difficile associated syndrome are discussed.

Development of an internal quality assessment scheme in a clinical bacteriology laboratory.

AIM: To develop an internal quality assessment (IQA) scheme in a clinical bacteriology laboratory. METHODS: Over 24 months, 1230 diagnostic specimens, representing 0.42% of laboratory workload, were anonymised and resubmitted for analysis. Six hundred and twenty one (48.7%) of these gave positive culture results; 44 fecal and upper respiratory specimens were "spiked" (artificially inoculated) to increase the proportion of positive samples. RESULTS: Discrepancies between IQA and clinical sample results occurred in 188 cases (14.8%): 76.6% of these were in culture results, 13.3% in microscopy performance, and 10.1% in clerical recording. The culture discrepancy rate for each positive sample was lowest for wound (17.5%) and urine (18.1%) specimens, and highest for faeces (34.9%) and upper respiratory (37.7%) samples. Discrepancies in several areas responded to staff training and improvement in technical methods. CONCLUSIONS: An IQA programme of this type assesses the reproducibility of tests within a diagnostic laboratory when analysing common specimen types and organisms. It permits blind assessment of many areas of diagnostic work that are not readily amenable to other quality assurance methods, and it raises the awareness of all staff to the importance of quality in every aspect of specimen and data processing.

Pyocin-sensitivity testing as a method of typing Pseudomonas aeruginosa: use of "phage-free" preparations of pyocin.

A method for pyocin-sensitivity typing by means of "phage-free" preparations of pyocin is described. The method was tested on 227 isolates of P. aeruginosa, collected from 34 different foci of infection in hospitals in the British Isles and the results were compared with those for combined serological and phage typing of all strains and pyocin production of 105 of the isolates. It is concluded that pyocin-sensitivity typing is a simple and reliable method giving a high degree of discrimination, comparable to that of combined serological and phage typing, and it is suitable for use in routine hospital laboratories.

Evidence that hospital hygiene is important in the control of methicillin-resistant Staphylococcus aureus.

Observational and microbiological data were collected from the patients and environment of a male general surgical ward over a period of 27 months from January 1998. Isolates of methicillin-resistant Staphylococcus aureus (MRSA) from patients and environment were typed by antibiogram, bacteriophage and pulsed field gel electrophoresis of chromosomal DNA. In September 1999, an intervention was put in place which included increasing the domestic cleaning time by 57 hours per week, with emphasis on removal of dust by vacuum cleaning, and allocation of responsibility for the routine cleaning of shared medical equipment. From January 1998 to September 1999, despite standard infection control measures (emphasis on hand hygiene, isolation of affected patients and staggered closure and cleaning of ward bays), 69 patients acquired a strain of E-MRSA16. This strain was also widespread in the ward environment. Typing confirmed that isolates from patients and environment were indistinguishable from one another and that the outbreak was due to a single strain. This strain was responsible for postoperative infection in approximately one third of the patients who acquired it. In the six months following the intervention, only three patients were colonized with the outbreak MRSA and monthly surveys failed to detect this strain in the environment. Thorough and continuous attention to ward hygiene and removal of dust was needed, to terminate a prolonged outbreak of MRSA infection on a general surgical ward, in addition to standard infection control measures. Control of hospital-acquired infection with MRSA requires a combination of measures, none of which are completely effective in isolation.

Spontaneous pseudomembranous colitis not associated with Clostridium difficile.

This paper describes two patients who developed macroscopically and microscopically typical pseudomembranous colitis without prior exposure to antimicrobial agents and without detectable Clostridium difficile or its toxin in the faeces.

Community-acquired Legionnaires' disease following minimal exposure to a contaminated source.

A case of community-acquired Legionnaires' disease (LD) is described. The source of infection was traced to a push-on tap at the end of a long spur from the hot circulation system in a large old residential building which had been unoccupied for several weeks. Legionella pneumophila serogroup 1 subgroup Pontiac was isolated from the patient's sputum and from the contaminated water supply. Isolates were shown to be indistinguishable from one another when subtyped by pulsed field gel electrophoresis of chromosomal DNA.

Intraventricular vancomycin for treatment of shunt-associated ventriculitis.

Twenty episodes of shunt-associated ventriculitis caused by staphylococci or streptococci were treated with intraventricular vancomycin together with removal of the shunt and insertion of an external drain. Systemic antibiotics given concurrently included intravenous vancomycin or flucloxacillin. All the patients responded to therapy although five had re-infections and one had a relapse. Four patients were treated solely with intrathecal vancomycin. We now use intraventricular vancomycin alone for 'blind' treatment of uncomplicated shunt-associated infections when Gram-positive cocci are seen in the ventricular CSF.

Variation in the infectivity of Listeria monocytogenes isolates following intragastric inoculation of mice.

The infectivities of 66 Listeria monocytogenes isolates were assessed by intragastric inoculation of mice. Eight were poorly infective. Serovars 4b and 1/2 were more infective than serovars 3 and 4nonb. A noninfective isolate was cleared more rapidly from the cecum than were infective isolates, suggesting that survival in the gut may relate to infectivity.

Nitrofurantoin resistance in isolates of Salmonella enteritidis phage type 4 from poultry and humans.

All 38 isolates of Salmonella enteritidis phage type (PT) 4 from chickens and 86 of 89 isolates from human patients were resistant to nitrofurantoin. Resistance to other agents was rare. Thirteen of 16 isolates of S. enteritidis other than PT4 were nitrofurantoin-resistant, and resistance to other agents was slightly more common than with isolates of PT4. Only one third of 83 isolates of other salmonella serotypes were nitrofurantoin-resistant, but resistance to other agents was more common and some isolates were multiply resistant. There was generally cross-resistance between nitrofurantoin and furazolidone although there were discrepancies with isolates that had MICs close to the breakpoint. It may be that use of nitrofurans in the poultry industry has selected for colonization and infection with S. enteritidis PT4. This could explain the prevalence of the organism in poultry and in human enteric infection in the United Kingdom.

Clostridium tertium septicemia in patients with neutropenia.

Eighteen adult patients with hematologic malignancy developed bacteremia due to Clostridium tertium while neutropenic. Fifteen had accompanying abdominal pain, colonic bleeding, or diarrhea, and three had perianal cellulitis. Fourteen recovered with antibiotic therapy alone; no patient was treated by surgery. C. tertium is an unusual Clostridium because it is resistant to many beta-lactam antibiotics and to metronidazole but is susceptible to vancomycin, trimethoprim-sulfamethoxazole, and ciprofloxacin. It is possible that use of third-generation cephalosporins (cefotaxime, ceftizoxime, ceftazidime) for treating febrile episodes in the absence of any selective intestinal decontamination with trimethoprim-sulfamethoxazole or ciprofloxacin may have resulted in selection for C. tertium in our patients.

Comparison of the infectivity of isolates of Listeria monocytogenes following intragastric and intravenous inoculation in mice.

The infectivity of 19 haemolytic isolates of Listeria monocytogenes from different sources (clinical and environmental) and representative isolates from Listeria ivanovii and Listeria innocua was compared following intragastric (i.g.) and intravenous (i.v.) inoculation in immunocompetent male BALB/c mice. There was marked variation in the infectivity of the different isolates by either route but when isolates were ranked in descending order by spleen count, following i.g. administration, the strains fell into four groups. Infectivity of some isolates also differed when i.v. inoculation was compared with i.g. administration, so that assessment of virulence by spleen counts only following i.v. inoculation might fail to detect isolates of poor infectivity by the i.g. route. These results suggest that intragastric inoculation of normal immunocompetent mice is a useful model for detecting strains of L. monocytogenes that are poorly invasive via the gut even though they are relatively virulent by intravenous inoculation.

Mechanism of nitrofuran resistance in Salmonella enteritidis phage type 4 and interpretation of nitrofuran susceptibility tests.

The mechanism of nitrofuran resistance in Salmonella enteritidis phage type 4 was studied. Nitrofuran reductase activity was inversely related to the furazolidone MIC for the organism. Strains with low-level nitrofuran resistance, typically found in almost all isolates of S. enteritidis PT4, had intermediate nitrofuran reductase activity. Disc diffusion tests with furazolidone, 15 or 50 micrograms discs, and nitrofurantoin, 50 or 300 micrograms discs, failed to distinguish reliably between susceptible populations and those with low-level resistance. In order to detect low-level resistance to nitrofurans a dilution method should be used with a furazolidone breakpoint of 1 mg/l or a nitrofurantoin breakpoint of 16 mg/l.

Salmonella enteritidis phage type 4 infection of broiler chickens: a hazard to public health.

The pericardial fluids and contents of caeca and spleens from 81 broiler chickens that had been condemmed at processing factories because of macroscopic pericarditis were examined for Salmonella species. 47 (58%) of these chickens yielded S enteritidis phage type (PT) 4. Viable counts of the organism in fluids from 6 of the most severely affected hearts ranged from 10(4) to 10(7) colony-forming units/ml. S enteridis PT4 was also isolated from 8 of 20 fresh chilled chickens on retail sale. No other serotype of Salmonella or phage type of S enteritidis was cultured either from the chickens with pericarditis or from the fresh chilled chicken.

Experimental induction of rheumatoid factor and joint lesions in rabbits after intravenous injections of killed bacteria.

Rabbits receiving repeated intravenous injections of killed bacteria (Escherichia coli or Bacillus subtilis) developed IgM rheumatoid factor which reacted with autologous heat-aggregated IgG. In addition, 5/7 'Old English' and 7/8 'Sandy Lop' rabbits receiving killed E. coli developed rheumatoid-like synovial lesions. 'Old English' rabbits developed lesions of a more severe nature. Three of eight 'Sandy Lop' rabbits injected with killed B. subtilis had high levels of rheumatoid factor but only mild joint lesions.

An outbreak of Vero cytotoxin producing Escherichia coli O157 infection associated with takeaway sandwiches.

An outbreak of food poisoning due to Escherichia coli O157 phage type 2 Vero cytotoxin 2 affected 26 people in southern counties of England in May and June 1995. The organism was isolated from faecal specimens from 23 patients, 16 of whom lived in Dorset and seven in Hampshire. Isolates were indistinguishable by phage typing, Vero cytotoxin gene typing, restriction fragment length polymorphism, and pulsed field gel electrophoresis. Three associated cases, linked epidemiologically to the outbreak, were confirmed serologically by detection of antibodies to E. coli O157 lipopolysaccharide. Twenty-two of the 26 patients were adults: four were admitted to hospital with haemorrhagic colitis. Four cases were children: two were admitted to hospital with haemolytic uraemic syndrome (HUS). There were no deaths. Although E. coli O157 was not isolated from any food samples, illness was associated with having eaten cold meats in sandwiches bought from two sandwich producers, in Weymouth and in Portsmouth. Both shops were supplied by the same wholesaler, who kept no records and obtained cooked meats from several sources in packs that did not carry adequate identification marks. It was, therefore, impossible to trace back to the original producer or to investigate further to determine the origin of contamination with E. coli O157. To protect the public health it is essential that all wholesale packs of ready-to-eat food carry date codes and the producer's identification mark. Detailed record keeping should be part of hazard analysis critical control point (HACCP) systems and should be maintained throughout the chain of distribution from the producer to retail outlets.