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An investigation into the microflora of heroin
J McLAUCHLIN, V Mithani, F J Bolton
1PHLS Food Safety Microbiology Laboratory, Central Public Health Laboratory and *Environmental Surveillance Unit, Communicable Disease Surveillance Centre, 61 Colindale Ave, London NW9 5HT, †Birkenhead & Wallasey Primary Care Trust, St Catherine's Hospital, Birkenhead, Merseyside CH42 0LP, ‡Communicable Disease Surveillance Centre (North West), Chester CH1 4EF, §South Sefton Primary Care Trust, Burlington House, Crosby Road North, Waterloo, Liverpool L22 0QB and ||Department of Public Health North West Region, Millennium Park, Birchwood, Warrington WA3 7QN.
Abstract:
In 2000, an unusual increase of morbidity and mortality among illegal injecting drug users in the UK and Ireland was reported and Clostridium novyi was identified as the likely source of the serious infection, although infections due to C. botulinum and Bacillus cereus were also reported. Because heroin was a possibile source of infection, this study investigated the microflora of heroin samples seized in England during 2000 and 2002. Two methods were developed for the examination of the microflora of heroin. The first consisted of suspension of the drug in maximum recovery diluent (MRD) which was inoculated directly into Clostridium Botulinum Isolation Cooked Meat Broth (CBI). The second method rendered the heroin soluble in citric acid, concentrated particulate material (and bacterial cells) by filtration and removed heroin residues by washing with citric acid and phosphate-buffered saline before placing the filter in CBI broth. Duplicate CBI broths from both methods were incubated without heating and after heating at 60 degrees C for 30 min. Subcultures were made after incubation for 7 and 14 days on to eight different solid media. The methods were evaluated with heroin samples spiked with either C. botulinum or C. novyi spore suspensions; recovery of 10 spores in the original sample was demonstrated. Fifty-eight heroin samples were tested by citric acid solubilisation and 34 by the MRD suspension technique. Fifteen different gram-positive species of four genera were recognised. No fungi were isolated. Aerobic endospore-forming bacteria (Bacillus spp. and Paenibacillus macerans) were the predominant microflora isolated and at least one species was isolated from each sample. B. cereus was the most common species and was isolated from 95% of all samples, with B. licheniformis isolated from 40%. Between one and five samples yielded cultures of B. coagulans, B. laterosporus, B. pumilus, B. subtilis and P. macerans. Staphylococcus spp. were isolated from 23 (40%) samples; S. warneri and S. epidermidis were the most common and were cultured from 13 (22%) and 6 (10%) samples respectively. One or two samples yielded cultures of S. aureus, S. capitis and S. haemolyticus. The remainder of the flora detected comprised two samples contaminated with C. perfringens and two samples with either C. sordellii or C. tertium. Multiple bacterial species were isolated from 43 (74%) samples, a single species from the remaining 15. In 13 samples B. cereus alone was isolated, in one B. subtilis alone and in one sample B. pumilus alone. C. botulinum and C. novyi were not isolated from any of the heroin samples. Recommendations for the optimal examination of the microflora of heroin are given.
Insights
Heroin samples from England contained various bacteria, primarily Bacillus cereus, but not the Clostridium species linked to user infections. This research highlights the diverse microbial contamination in illicit drug supplies.
Area of Science:
- Microbiology
- Public Health
- Forensic Science
Background:
- An increase in morbidity and mortality among injecting drug users in the UK and Ireland was linked to Clostridium novyi infections in 2000.
- Heroin was suspected as a potential source of these serious infections, prompting an investigation into its microbial content.
Purpose of the Study:
- To investigate the microflora present in heroin samples seized in England between 2000 and 2002.
- To develop and evaluate methods for detecting bacteria in heroin samples.
Main Methods:
- Two methods were developed: direct suspension in maximum recovery diluent (MRD) and citric acid solubilisation followed by filtration.
- Samples were incubated in Clostridium Botulinum Isolation Cooked Meat Broth (CBI) with and without heat treatment.
- Methods were validated using spiked heroin samples with known bacterial spores (C. botulinum, C. novyi).
Main Results:
- Aerobic endospore-forming bacteria, predominantly Bacillus species, were the most common contaminants, found in all samples.
- Bacillus cereus was isolated from 95% of samples, with Bacillus licheniformis found in 40%.
- Clostridium botulinum and Clostridium novyi were not detected in any of the analyzed heroin samples.
Conclusions:
- Heroin samples harbor a diverse range of bacteria, with Bacillus species being the predominant microflora.
- The study did not find evidence linking the investigated heroin samples to the Clostridium infections reported in drug users.
- Recommendations are provided for optimizing the examination of heroin microflora.