Infections in Injection Drug Users: The Significance of Oral Bacteria and a Comparison with Bacteria Originating from Skin and Environmental Sources

Abstract

Infections are common in IV drug users (IVDU). Heroin was by far the most common drug abused in our series of 80 patients. The spectrum of infections in our patients with ages ranging from 20-63, varied from mild skin infections to life threatening and fatal conditions such as septic shock, necrotizing fasciitis, spinal cord infarction and endocarditis with cerebral septic emboli. Our studies showed that bacterial infections in IV drug users originate from three different sources: 1. Skin (contaminated hands) 2. Oral microbiota 3. Environmental sources including water, soil and plants. The most common skin bacteria isolated were methicillin susceptible and methicillin resistant Staphylococcus aureus (MSSA and MRSA). In our study Streptococcus anginosus group was the most common oral bacteria in IVDU with Streptococcus intermedius predominating, followed by group A Streptococcus, Prevotella spp., Eikenella corrodens, Haemophilus parainfluenzae and group C Streptococcus. A variety of environmental bacteria were isolated, but the total number of patients in this group was smaller. Bacteria originating from water, soil or plants present were: Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Delftia acidovorans, Commamonas sp., Chryseobacterium spp., Klebsiella spp., Serratia marcesens, Burkholderia cepacia, Pseudomonas fluorescence and Acinetobacter. Twenty four out of 48 (50%) Staphylococcus aureusinfected patients were bacteremic, followed by 6/10 (60%) group A Streptococcus infected cases. Life threatening infections were more common with those infected with Staphylococcus aureus or Pseudomonas aeruginosa. Few had Candida sp., likely of oral origin. Hepatitis C was less common (2/37) 5.4% in the group with oral bacteria and more frequent in MSSA/MRSA patients (13/47) 27.7%. There was 1 coinfection with human immunodeficiency virus each in oral and skin bacteria associated groups. The bacteria isolated provided a clue to the source of infections and habits of the IV drug users.