Background
This is a summary of a public health alert (local copy) alert in response to two cases of Clostridium novyi infection in injecting drug users since June 2008, in Kent and Essex, with one case a fatality. Thus follows a previous similar cluster in Ireland and the UK.
Local signs
Local inflammation at a subcutaneous/intramuscular injection site. Variable features including: oedema (often extensive), myositis, erythema, cellulitis, bruised appearance, abscess-like (with little/no pus), blackened/blistered centre, necrosis, necrotising fasciitis. Usually painful
- characteristically not associated with high fever
- difficult to distinguish from other types of soft tissue inflammation
- ask about injecting practices and substances co-injected with heroin
- examine all injection sites for signs of local inflammation
Systemic signs
- Several days after local lesion
- dramatic deterioration
- Circulatory collapse ±ARDS ±DIC
- WCC >30,000 cells/mm3
- Often mentally alert until late stage
- look for unusual local lesions in collapsed drug users
Management
- Prompt treatment crucial
- Consider early surgical treatment (exploration, drainage, debridement)
- Antimicrobials according to local protocol and other clinical indications but including agents active against clostridia
- Severe cases should be admitted for consideration of surgical treatment, IV antibiotics (one/combination of penicillin, metronidazole, clindamycin (not alone)), microbiological investigation and close observation in a high dependency unit
- Cases treated as outpatients should also be considered for surgical intervention, have microbiological sampling and receive antibiotics active against anaerobes when given orally (amoxycillin, co-amoxiclav, metronidazole, and clindamycin (not alone)). Any inflammation at an injection site should be examined daily until it has subsided
Labs
Specimen Collection Protocol For Clinicians For Microbiological Investigation of Severe Systemic Sepsis related to Soft Tissue Inflammation Amongst Injection Drug Users.
Microbiological investigation
Please collect the following specimens for culture in order of priority and transport to your local laboratory as quickly as possible. Please notify the hospital microbiologist that you have a suspect case.
- biopsy tissues from local inflammatory lesions
- pus/swab of local lesion(s)
- blood cultures - at least 2 sets
- Any other relevant samples
The following is a guide for clinicians when taking specimens from potential case-patients. In addition to examination in your own laboratory, it is possible that these specimens may be sent to various specialist laboratories for further microbiological and toxicological analysis.
If possible specimens should be collected and transported to a clinical microbiology laboratory as rapidly as possible for testing, and storage. As there is evidence that anaerobic organisms are possibly involved in the aetiology of these cases, speed and maximum efforts to maintain anaerobic conditions in transport of specimens are important. Optimal recovery of fastidious anaerobes is best achieved if samples are processed as soon as possible e.g. within one hour of collection and if exposure to oxygen is kept to a minimum. The experiences of the microbiology investigation team involved in the C. novyi outbreak was published by Brazier et al (2002)1. This report contains advice on optimal isolation and identification of clostridia from IDU’s. It may be appropriate to arrange for urgent transportation of the specimen(s) to the microbiology laboratory and immediate processing, if a delay is otherwise anticipated.
Please collect the following specimens in order of priority together with any other specimen as clinically indicated. (Please note that though tissue biopsy samples are the most useful, blood cultures and pus/swabs should be collected as soon as possible after admission)
Biopsy tissues collected aseptically from local inflammatory lesion, necrosis or abscess, if surgical debridement is performed:
- several samples if possible, quantity is important;
- tissue placed in sterile containers for direct culture (aerobic and anaerobic) and freezing; and
- formalin-fixed (10% buffered formalin) or paraffin embedded for histology
Pus or swab of local lesion:
- pus, as large a volume as feasible, placed in sterile containers for microscopy;
- aerobic and anaerobic culture; and
- if no pus available, swab of lesion put immediately into transport media for aerobic and anaerobic culture
Blood cultures:
- ideally at least 2 sets of blood cultures, with at least 1 set prior to antibiotic administration
Serum:
- for local investigations and retention (for possible further testing as appropriate); but NOTEIF the clinical picture is suggestive of wound botulism a serum sample should be forwarded as soon as possible to the HPA, Food Safety Microbiology Laboratory ( tel: 0044()20 82004400) for the appropriate toxin assay to be performed
Other Body fluids:
- if other, normally sterile, fluid specimens are taken as part of the clinical work-up, please ask laboratory to retain the samples rather than discarding after standard testing
Please see general approach to severe sepsis and goal directed therapy on severe sepsis page