Management of hospital outbreaks of gastro-enteritis due to small roundstructured viruses

Small round structured viruses (SRSVs, Norwalk-like viruses, NLVs) are the most common cause of outbreaks of gastro-enteritis in hospitals and also cause outbreaks in other settings such as schools, hotels, nursing homes and cruise ships. Hospital outbreaks often lead to ward closure and major disruption in hospital activity. Outbreaks usually affect both patients and staff, sometimes with attack rates in excess of 50%. For this reason, staff shortages can be severe, particularly if several wards are involved at the same time. SRSVs may be spread by several routes: faecal-oral; vomiting/aerosols; food and water. Viruses may be introduced into the ward environment by any of these routes and then propagated by person-to-person spread. In an outbreak setting, the diagnosis can usually be made rapidly and confidently on clinical and epidemiological grounds, particularly if vomiting is a prominent symptom. By the time an SRSV outbreak has been recognized at ward level, most susceptible individuals will have been exposed to the virus and infection control efforts must prioritize the prevention of spread of infection to other clinical areas bycontainment of infected/exposed individuals (especially the prevention of patient and staff movements to other areas), hand-hygiene and effective environmental decontamination. This report of the Public Health Laboratory Service Viral Gastro-enteritis Working Group reviews the epidemiology of outbreaks of infection due to SRSVs and makes recommendations for their management in the hospital setting. The basic principles which underpin these recommendations will also be applicable to the management of some community-based institutional outbreaks.

Impact of changes in antibiotic policy on Clostridium difficile-associated diarrhoea (CDAD) over a five-year period in a district general hospital

The impact of changes in antibiotic policy on Clostridium difficile-associated diarrhoea (CDAD), over a five-year period between 1995 and 2000, were studied in the Preston Acute Hospitals Trust. In 1996 the policy was changed in the Preston Acute Hospitals Trust from cefotaxime to ceftriaxone for initial treatment of severe sepsis or pneumonia in medical patients. Over the next nine months the average number of patients with C. difficile toxin-positive stools per quarter increased from 16 to 39. The predicted use of ceftriaxone exceeded by 65% an estimate based on prior use of cefotaxime. A policy of restricted duration of ceftriaxone was introduced, and although this reduced usage by over 50%, CDAD continued at an average of 9.2 cases per month, despite withdrawal of oral cephalosporins in December 1998. In August 1999 levofloxacin was substituted for ceftriaxone in the policy. The incidence of CDAD fell progressively to five cases per month by 2000. It would appear that a short (typically three dose) course of third-generation cephalosporin poses a similar risk for CDAD as a more prolonged course. The six-month delay in the decline of CDAD after virtual withdrawal of cephalosporins may reflect a slowly diminishing environmental reservoir.

Randomized prospective study comparing vancomycin with teicoplanin in the treatment of infections associated with Hickman catheters

In 72 episodes of suspected or proven Hickman-catheter-associated infection occurring in 59 patients with various hematological disorders, patients were assigned to treatment with either vancomycin or teicoplanin in a randomized nonblinded prospective study. Of 60 episodes evaluable for response, 28 were treated with vancomycin and 32 were treated with teicoplanin. Sixteen infective episodes were microbiologically documented in the vancomycin group, and twenty-one were microbiologically documented in the teicoplanin group. Microbiologically and clinically documented infections treated with vancomycin had an 80% response rate, compared with a 69% response rate for those treated with teicoplanin (P = 0.316). Adverse events occurred in nine (25%) of the episodes in the vancomycin group, compared with three (8%) in the teicoplanin group (P = 0.044). Teicoplanin may provide an effective alternative to vancomycin in the treatment of Hickman-catheter-associated infection in patients with hematological malignancies.

Streptococcal toxic shock-like syndrome: evidence of superantigen activity and its effects on T lymphocyte subsets in vivo

Toxic shock-like syndrome is a serious complication of invasive streptococcal disease. The syndrome is believed to be the consequence of exposure to exotoxins produced by the infecting organisms which behave as superantigens. We describe two patients who fulfilled clinical criteria for this syndrome, one of whom died. Streptococci isolated from both patients were found to produce a mitogen specific for the V beta 2+ T lymphocyte subset in vitro, which had the characteristics of a superantigen. The phenotype and function of lymphocytes collected from both patients during the acute phase of their illness demonstrated a marked reduction in circulating CD4+ ('helper') and CD45RA+ ('naive') T lymphocytes expressing the V beta 2 chain, and an increase of those expressing CD8, CD45RO and the V beta 2 chain. This effect resolved within 4 weeks in the patient who survived. Proliferation assays demonstrated no T cell anergy in either patient. Stimulation of lymphocytes by superantigen in these clinical situations does not appear to cause permanent deletion of T cell subsets, as has been observed in animal models.

Streptobacillus moniliformis isolated from blood in four cases of Haverhill fever

During February, 1983, an outbreak of an unusual febrile illness occurred in over 130 children attending a boarding school in Chelmsford, Essex. The clinical features included fever, an erythematous rash that was most prominent on the hands and feet, arthralgia, and the subsequent development of a sore throat. The nature and distribution of the rash varied considerably between patients and at different stages of illness. At first a viral aetiology was regarded as most likely. When Streptobacillus moniliformis was later isolated from the blood of 4 of the patients with moderately severe illnesses it became apparent that an outbreak of Haverhill fever had occurred at this school. The most probable source of the outbreak was raw milk, since all 4 patients had consumed raw milk at the school shortly before the onset of symptoms and there was no evidence of person-to-person spread of infection.

Blood pressure cuffs: friend or foe?

A study to assess the level of bacterial contamination of blood pressure cuffs in use on hospital wards was performed. Viable organisms were recovered from all the 24 cuffs sampled at a density of between 1000 and >25 000 colony-forming units/100 cm2. Potential pathogens were isolated from 14 cuffs (58%). Eleven cuffs grew a single pathogen and three cuffs grew a mixture, yielding a total of 18 isolates. Meticillin-susceptible Staphylococcus aureus was isolated from eight (33%) cuffs, meticillin-resistant S. aureus was isolated from two (8%) cuffs and Clostridium difficile was isolated from eight (33%) cuffs. This study serves as a reminder that hands are not the only fomite to go from patient to patient on hospital wards, and that measures should be taken to reduce the risks posed by blood pressure cuffs.

Spatio-temporal epidemiology of Campylobacter jejuni enteritis, in an area of Northwest England, 2000-2002

A total of 969 isolates of Campylobacter jejuni originating in the Preston, Lancashire postcode district over a 3-year period were characterized using multi-locus sequence typing. Recently developed statistical methods and a genetic model were used to investigate temporal, spatial, spatio-temporal and genetic variation in human C. jejuni infections. The analysis of the data showed statistically significant seasonal variation, spatial clustering, small-scale spatio-temporal clustering and spatio-temporal interaction in the overall pattern of incidence, and spatial segregation in cases classified according to their most likely species-of-origin.

Typing of Salmonella enterica serotype paratyphi C isolates from various countries by plasmid profiles and pulsed-field gel electrophoresis

Pulsed-field gel electrophoresis (PFGE) of 61 Salmonella enterica serotype Paratyphi C isolates from six countries gave five distinct clusters. Twenty-four isolates from five countries were susceptible to 10 antimicrobials tested and gave similar restriction endonuclease digest patterns of the 38-MDa plasmid. In contrast, plasmid and PFGE profiles of 37 multidrug-resistant isolates from Zaire were different from those from other countries.

A rationalised virological electron microscope specimen testing policy. PHLS North West Viral Gastroenteritis and Electron Microscopy Subcommittee

The aim of this project was to produce guidance for a rationalised virological electron microscopy specimen testing policy for PHLS North West, to facilitate centralisation of a groupwide diagnostic electron microscopy service on a single site. Careful specimen selection to limit numbers and the groupwide use of commercially available enzyme immunoassays has allowed PHLS North West to reduce the number of specimens prepared for electron microscopy. The rationalised virological electron microscopy specimen testing policy has enabled a diagnostic electron microscopy service to be provided from a single site with a manageable workload. Implementation of this specimen testing policy by PHLS North West has been successful and may be applicable to other laboratories (or groups of laboratories) to maximise the use of expensive electron microscopy facilities.

Specific detection of Campylobacter jejuni from faeces using single nucleotide polymorphisms

Specimens of human faeces were tested by a rapid strategy for detection of Campylobacter jejuni lineages by the presence of specific single nucleotide polymorphisms (SNPs) based on the C. jejuni multi locus sequence typing (MLST) scheme. This strategy was derived from analysis of the MLST databases to identify clonal complex specific SNPs followed by the design of real-time PCR assays to enable identification of six major C. jejuni clonal complexes associated with cases of human infection. The objective was to use the MLST SNP-based assays for the direct detection of C. jejuni by clonal complex from specimens of human faeces, and then confirm the accuracy of the clonal complex designation from the SNP-based assays by performing MLST on the cultured faecal material, this targeted at determining the validity of direct molecular specimen identification. Results showed it was possible to identify 38% of the isolates to one of the six major MLST clonal complexes using a rapid DNA extraction method directly from faeces in under 3 h. This method provides a novel strategy for the use of real-time PCR for detection and characterization beyond species level, supplying real-time epidemiological data, which is comparable with MLST results.

Severe sepsis following wound infection by an unusual organism--Clostridium novyi

We present a case of post-operative wound infection with Clostridium novyi in a non-intravenous drug user. Clinical features included progressive cellulitis despite being on antibiotics, accompanied by hypotension, marked leucocytosis and oedema but minimal fever. While established infection with this organism is associated with high mortality, our patient survived. The administration of clindamycin and intravenous immunoglobulin in addition to early surgical assessment and aggressive debridement of affected tissue may have contributed to this successful outcome. To our knowledge, this is the only reported post-operative wound infection due to this pathogen.

Comparative activity of glycopeptide antibiotics against coagulase-negative staphylococci embedded in fibrin clots

The susceptibilities of 16 strains of coagulase-negative staphylococci to vancomycin and teicoplanin were determined by three microdilution methods run in parallel; (i) a reference method in which the medium was Iso-Sensitest broth, (ii) a method in which the organisms were suspended in plasma and (iii) one in which the bacteria were incorporated into a fibrin clot. In comparison with the reference method there was a less than two-fold change in the geometric mean MICs of both antibiotics in plasma, while in clot the increase was 12-fold for vancomycin and 28-fold for teicoplanin. MBCs showed a similar trend although the increase was greater for teicoplanin. These results suggest that protein binding may have a much greater impact on antimicrobial activity when the mobility of the protein is reduced within a clot.

Role of glycopeptide antibiotics in the treatment of febrile neutropenic patients

The exact timing of the introduction of the glycopeptide antibiotics teicoplanin and vancomycin in the management of the febrile neutropenic patient continues to be controversial. However, there are certain firm criteria now emerging. Bacteraemia can be eradicated with a success rate approaching 100% in cases where the organism can be identified and shown to be sensitive. Approximately 65% of cases of soft-tissue infection, usually occurring with the use of a Hickman or equivalent indwelling catheter, are associated with the presence on culture of Gram-positive organisms of presumed skin origin. Such infection is an indication for the early use of antibiotics with proven activity against coagulase-negative staphylococci and diptheroids. Resolution of fever in up to 50% of cases may result from using 'planned progressive therapy': the introduction of specific Gram-positive cover in patients who have failed to respond at 48-72 h to regimens such as a ureidopenicillin or a third-generation cephalosporin with or without an aminoglycoside. This approach reduces the number of patients who go on to receive empirical amphotericin B intravenously for presumed fungal infection. Using teicoplanin or vancomycin as first-line agents in the empirical treatment of first fever in febrile neutropenic patients is perhaps more controversial. Recent developments which include using quinolone-based prophylaxis more widely and introducing cytokines to reduce the period of neutropenia may increase the likelihood that a neutropenic patient's febrile episode will be due to a Gram-positive organism. The dilemma of choosing broad-spectrum monotherapy or targeted combination therapy in the situation remains unresolved. Current studies, however, should help to clarify this situation. Finally, other current studies of teicoplanin and vancomycin as prophylactic agents administered either orally or systemically, may provide additional indications for their use in the neutropenic patient.

Large outbreak of infection with Escherichia coli O157 PT21/28 in Eccleston, Lancashire, due to cross contamination at a butcher's counter

An outbreak of infection with Escherichia coli O157 Phage Type 21/28 occurred between the 23rd November 2001 and the 7th December 2001 in Eccleston, Lancashire. There were 30 confirmed cases (23 with positive faecal isolates and seven serologically positive). Eccleston is a village of approximately 5,000 inhabitants with a single medical practice where many of the cases were patients. Initial investigations identified the suspected source as a butcher's counter, operated as a franchise, in a supermarket in Eccleston. The butcher closed voluntarily on the 24th November. The median age of cases was 60 with a mean of 56 and a range of 2-91 years. Of the 30 confirmed cases, 22 were admitted to hospital. Two patients developed serious complications but all 30 made a full recovery. Microbiological investigations confirmed the butcher's counter as the source of the outbreak. The epidemiological evidence implicated cooked meats and microbiological evidence confirmed that contamination had occurred between raw and cooked meats. The deficiencies in meat hygiene practice that were identified could have led to the cross contamination. This outbreak illustrates the risk associated with the handling of raw and cooked meats in the same shop. Complete physical separation of raw and cooked meat operations reduces the risk of such outbreaks.