Guidance for the decontamination of intracavity medical devices: the report of a working group of the Healthcare Infection Society

BACKGROUND

Intracavity medical devices (ICMDs) are used in a wide variety of healthcare settings. The approach to their decontamination and the resources available also differ widely. Their potential for infection transmission is considerable.

AIM

To produce a comprehensive risk assessment-based approach to the decontamination of ICMDs, accompanied by an adaptable audit tool.

KEY RECOMMENDATIONS

Infection control measures to limit the spread of Clostridium difficile

Clostridium difficile-associated diarrhoea (CDAD) presents mainly as a nosocomial infection, usually after antimicrobial therapy. Many outbreaks have been attributed to C. difficile, some due to a new hyper-virulent strain that may cause more severe disease and a worse patient outcome. As a result of CDAD, large numbers of C. difficile spores may be excreted by affected patients. Spores then survive for months in the environment; they cannot be destroyed by standard alcohol-based hand disinfection, and persist despite usual environmental cleaning agents. All these factors increase the risk of C. difficile transmission. Once CDAD is diagnosed in a patient, immediate implementation of appropriate infection control measures is mandatory in order to prevent further spread within the hospital. The quality and quantity of antibiotic prescribing should be reviewed to minimise the selective pressure for CDAD. This article provides a review of the literature that can be used for evidence-based guidelines to limit the spread of C. difficile. These include early diagnosis of CDAD, surveillance of CDAD cases, education of staff, appropriate use of isolation precautions, hand hygiene, protective clothing, environmental cleaning and cleaning of medical equipment, good antibiotic stewardship, and specific measures during outbreaks. Existing local protocols and practices for the control of C. difficile should be carefully reviewed and modified if necessary.

Fungal septicaemia in patients with cystic fibrosis associated with totally implantable venous access device system

Fungal septicaemia is a serious and potentially fatal condition. We report 4 cases in patients with Cystic Fibrosis (CF) associated with totally implantable venous access device system (TIVADS).

Pulmonary Mycobacterium kansasii infection: comparison of radiological appearances with pulmonary tuberculosis

BACKGROUND

A study was undertaken to determine if there are differences in the radiological appearances at presentation between pulmonary infections caused by Mycobacterium kansasii and Mycobacterium tuberculosis. Correct recognition of the organism has important implications with regard to initial therapy and contact tracing.

METHODS

The initial chest radiographs of 28 patients with pulmonary M kansasii infection were compared with those of 56 age, sex, and race matched patients with M tuberculosis infection. All patients in both groups were culture positive and none was known to be HIV positive. The radiographs were analysed independently by two radiologists who were unaware of the causative organism.

RESULTS

Radiographic abnormalities in patients with M kansasii infection were more frequently unilateral and right side predominant, while those with tuberculosis more frequently involved a lower lobe. Air space shadowing involving more than one bronchopulmonary segment and pleural effusions were seen less frequently in M kansasii infection (four of 28 (14%) versus 30 of 56 (54%) and none of 28 versus 15 of 56 (27%)). Cavitation (21 of 28 (75%) versus 34 of 56 (61%) was seen to a similar extent in patients with M kansasii infection and in those with tuberculosis. Cavities tended to be smaller in patients with M kansasii infection (p < 0.01).

CONCLUSIONS

Differences are seen in the radiographic appearances of pulmonary infection caused by M kansasii and M tuberculosis. These differences are not sufficient to allow a positive diagnosis on the basis of radiographic findings alone, but the presence of a pleural effusion or lower lobe involvement makes M kansasii infection very unlikely.

Pulmonary Mycobacterium kansasii infection: comparison of the clinical features, treatment and outcome with pulmonary tuberculosis

BACKGROUND

In the United Kingdom Mycobacterium kansasii is the most common pulmonary non-tuberculous mycobacteria to cause disease in the non-HIV positive population.

METHODS

The clinical features, treatment, and outcome of 47 patients (13 women) of mean (SD) age 58 (17) years with culture positive pulmonary M kansasii infection were compared with those of 87 patients (23 women) of mean (SD) age 57 (16) years with culture positive pulmonary M tuberculosis infection by review of their clinical and laboratory records. Each patient with M kansasii infection was matched for age, sex, race and, where possible, year of diagnosis with two patients with M tuberculosis infection.

RESULTS

All those with M kansasii infection were of white race. Haemoptysis was more common in patients infected with M kansasii but they were less likely to present as a result of an incidental chest radiograph or symptoms other than those due to mycobacterial infection. Patients with M kansasii were also less likely to have a history of diabetes, but the frequency of previous chest disease and tuberculosis was similar. An alcohol intake of > 14 units/week was less frequent in those with M kansasii, but there were no significant differences in drug history, past and present smoking habit, occupational exposures, social class, or marital status. Patients with M kansasii received a longer total course of antimycobacterial therapy and, in particular, extended treatment with ethambutol and rifampicin was given. There was no significant difference in outcome between pulmonary M kansasii or M tuberculosis infection.

CONCLUSIONS

There are group differences between the clinical features of the two infections but, with the possible exception of diabetes and alcohol intake, these features are unlikely to be diagnostically helpful. Treatment of M kansasii infection with ethambutol, isoniazid, and rifampicin in these patients was as effective as standard regimens given to patients infected with M tuberculosis.

A new method for active surveillance of adverse events from diphtheria/tetanus/pertussis and measles/mumps/rubella vaccines

We describe a new method for active post-marketing surveillance of vaccine safety based on patient records. We studied the association between diphtheria/tetanus/pertussis (DTP) vaccination and febrile convulsion, and between measles/mumps/rubella (MMR) vaccination and febrile convulsion and idiopathic thrombocytopenic purpura (ITP) in five district health authorities in England by linking vaccination records with computerised hospital admission records. We found an increased relative incidence for convulsions 0-3 days after DTP vaccination. The effect was limited to the third dose of vaccine for which the attributable risk (all ages) was 1 in 12,500 doses. Completion of vaccination by 4 months instead of 10 months after the change in the UK to an accelerated immunisation schedule may have resulted in a 4-fold decrease in febrile convulsions attributable to DTP vaccine. 67% of admissions for a convulsion 6-11 days after MMR vaccination were attributable to the measles component of the vaccine (risk 1 in 3000 doses). An excess of admissions for a convulsion 15-35 days after MMR vaccination was found only for vaccines containing the Urabe mumps strain (1 in 2600 Urabe doses). There was a causal association between MMR vaccination and ITP resulting in admission 15-35 days subsequently; there was no evidence of a mumps strain-specific effect. The estimated absolute risk of 1 in 24,000 doses was 5 times that calculated from cases passively reported by clinicians. This finding emphasises the need for active surveillance of adverse events. The record linkage method that we used is an effective way to identify vaccine-attributable adverse events.

Pulmonary infections caused by Mycobacterium malmoense and Mycobacterium tuberculosis: comparison of radiographic features

OBJECTIVE

The purpose of this study was to compare the radiographic features seen at presentation of pulmonary infections caused by Mycobacterium malmoense and Mycobacterium tuberculosis. The correct differential diagnosis has important therapeutic implications.

MATERIALS AND METHODS

The initial radiographs of 16 patients who had proved pulmonary M. malmoense infection were compared with those of 32 age-, sex-, and race-matched patients who had M. tuberculosis infection. The radiographs were analyzed by two radiologists who had no knowledge of the infecting organism. For statistical comparisons, chi 2 and Fisher's exact tests were used.

RESULTS

Radiographic findings seen more often in patients who had M. malmoense infection than in those who had tuberculosis were as follows: cavities larger than 6 cm in diameter were found in six (37%) of 16 vs two (6%) of 32 (p < .01); air-fluid levels within cavities were seen in four (25%) of 16 vs one (3%) of 32 (p < .05); loss of lung volume was observed in 12 (75%) of 16 vs 11 (34%) of 32 (p < .01); and coexistent pneumoconiosis was present in four (25%) of 16 vs none of 32 (p < .01). Air-space shadowing involving more than one bronchopulmonary segment was less common in the M. malmoense group, seen in three (19%) of 16 patients, than in the M. tuberculosis group, seen in 16 (50%) of 32 patients (p < .05).

CONCLUSION

The radiographic appearances of pulmonary infection caused by M. malmoense differ from those of pulmonary tuberculosis. These differences do not appear to be sufficient to allow a specific diagnosis on the basis of radiographic findings alone.

A rare complication of dental treatment: Streptococcus oralis meningitis

A case of Streptococcus oralis meningitis is reported. This followed extraction of a normal tooth during routine orthodontic treatment. No focus of infection could be demonstrated, either local to or distant from the extraction site. Full recovery followed hospital admission and intravenous benzyl penicillin.

Risk of aseptic meningitis after measles, mumps, and rubella vaccine in UK children

Cases of aseptic meningitis associated with measles/mumps/rubella vaccine were sought in thirteen UK health districts following a reported cluster in Nottingham which suggested a risk of 1 in 4000 doses, substantially higher than previous estimates based on cases reported by paediatricians (4 per million). Cases were ascertained by obtaining vaccination records of children with aseptic meningitis diagnosed from cerebrospinal fluid samples submitted to Public Health Laboratories or discharged from hospital with a diagnosis of viral meningitis. Both methods identified vaccination 15-35 days before onset as a significant risk factor and therefore indicative of a causal association. With both, half the aseptic meningitis cases identified in children aged 12-24 months were vaccine-associated with onset 15-35 days after vaccine. The study confirmed that the true risk was substantially higher than suggested by case reports from paediatricians, probably about 1 in 11,000 doses. However, the possibility that the aseptic meningitis induced by vaccination was largely asymptomatic and a chance laboratory finding in children investigated for other clinical conditions, particularly febrile convulsions, could not be excluded. Comparison of national reports of virus-positive mumps meningitis cases before and after the introduction of this vaccine indicated that the risk from wild mumps was about 4-fold higher than from vaccine. Altogether, 28 vaccine-associated cases were identified, all in recipients of vaccines containing the Urabe mumps strain. The absence of cases in recipients of vaccine containing the Jeryl Lynn strain, despite its 14% market share, suggested a higher risk from Urabe vaccine. A prospective adverse event surveillance system using the study methods is currently being established to assess the risk, if any, from the Jeryl Lynn strain which is now the only mumps vaccine used in the UK.

Retrospective review of culture-positive mycobacterial lymphadenitis cases in children in Nottingham, 1979-1990

Laboratory records were reviewed retrospectively for culture-positive cases of mycobacterial lymphadenitis in children less than 15 years old. There were six cases of Mycobacterium tuberculosis infection, and 15 cases of infection with other mycobacteria. There were no clinical features to distinguish tuberculous from non-tuberculous cases. All cases managed by chest physicians were initially treated as tuberculosis, whereas paediatric specialists were likely to use initial management appropriate to the infecting organism. Methods of improving the initial management of non-tuberculous infections are discussed.

Prospective study of aetiology and outcome of adult lower-respiratory-tract infections in the community

Community-acquired adult lower-respiratory-tract infections (LRTI) are generally thought to be caused by atypical and viral infections. We have studied 480 adults presenting to a single general practice with community-acquired LRTI between November, 1990, and December, 1991. The overall incidence was 44 cases per 1000 population per year; the incidence was 2-4 times higher in people aged 60 and over than in those aged less than 50. 206 patients were studied in detail; among this group 91 (44%) had 113 pathogens identified. There were 92 bacteria (Streptococcus pneumoniae in 62 and Haemophilus influenzae in 16), 19 viruses (influenza virus in 12), and only 2 atypical pathogens (Mycoplasma pneumoniae and Coxiella burnetii). Pneumococcal infection was common in people who were 60 or older, those who had underlying chronic disease, or people with both features. There was moderate morbidity in terms of time in bed, time to return to normal activities, and days off work. 25% of patients returned for a second consultation with the general practitioner, in most because of unsatisfactory clinical progress. Community-acquired LRTI are very common, and the range of causative pathogens is similar to that for community-acquired pneumonia. Existing management strategies seem inadequate.

Outbreak of Legionnaires' disease at University Hospital, Nottingham. Epidemiology, microbiology and control

Twelve patients in a large teaching hospital contracted Legionnaires' disease over a period of 11 months. The source was a domestic hot water system in one of the hospital blocks, which was run at a temperature of 43 degrees C. Five different subtypes of Legionella pneumophila serogroup 1 have been isolated from water in different parts of the hospital, over a period of time. Only one subtype, Benidorm RFLP 14, was implicated in disease. Circumstantial evidence suggested that the outbreak may have been due to recent colonization of the hot water system with a virulent strain of Legionella pneumophila. The outbreak was controlled by raising the hot water temperature to 60 degrees C, but careful surveillance uncovered two further cases in the following 30 months. Persistent low numbers of Legionella pneumophila were isolated from the domestic hot water of wards where Legionnaires' disease had been contracted, until an electrolytic unit was installed releasing silver and copper ions into this supply.

Mycobacterial cervical lymphadenitis in children: can histological assessment help differentiate infections caused by non-tuberculous mycobacteria from Mycobacterium tuberculosis?

Most mycobacterial lymphadenitis in children in developed countries is caused by non-tuberculous (the so-called 'atypical') mycobacteria. In view of the widely different treatment regimes and the requirement for contact tracing in Mycobacterium tuberculosis infections but not in non-tuberculous mycobacterial infections, it is very important to attempt to define histologically which is the aetiological agent. We have reviewed the histological appearances of mycobacterial cervical lymphadenitis in children and have found that, if any one of several 'atypical' features were seen, the appearances were much more likely to be due to a non-tuberculous mycobacterium. These features include ill-defined (non-palisading) granulomas, irregular or serpiginous granulomas, a predominantly non-specific granulomatous response, predominantly sarcoid-like granulomas or lack of significant caseation. In addition, the non-tuberculous mycobacterial infections showed a different distribution of neutrophil polymorphs, which tended to be seen in the centre of areas of necrosis rather than in Mycobacterium tuberculosis infections where a polymorph infiltrate, if present, was more diffusely scattered. Although no one definitive feature is diagnostic of non-tuberculous mycobacterial infection, some features are helpful in differentiating the two groups of organisms histologically.