Microbiology and Antibiotic Treatment among Injection Drug Users and Non-Injection Drug Users Hospitalized with Acute Bacterial Skin and Skin Structure Infection
Methods: This was a secondary analysis of two published cohorts of patients hospitalized for cellulitis or cutaneous abscess. Injection drug use was defined as documentation of last use within 6 months prior to hospitalization. Microbiology and antibiotic utilization were compared among patients with and without injection drug use. Antibiotics with broad anaerobic activity were defined as β-lactamase inhibitor combinations, clindamycin, carbapenems, and metronidazole.
Results: Of 770 patients hospitalized for ABSSSI, 126 (16%) were injection drug users. Compared with non-injection drug users, injection drug users were more likely to have an abscess as the presenting infection (83% vs 34% of cases, p<.001). Injection drug users were also younger (median age 43 vs. 51 years, p<.001) and more likely to have upper extremity involvement (18% vs 9%, p = .005), multiple sites of infection (10% vs 5%, p = .02), HIV infection (10% vs 2%, p<.001), and a prior skin infection (31% vs 22%, p = .03). In cases where a microorganism was cultured, streptococcal species (50% vs 27%, p<.001) and anaerobes (29% vs 8%, p<.001) were more common among injection drug users, while Staphylococcus aureuswas less common (52% vs 67%, p = .02). These findings were similar when limiting the analysis to cases involving an abscess. Injection drug users were treated with antibiotics with broad anaerobic activity more frequently than non-injection drug users (69% vs 60%, p = .048), particularly with β-lactamase inhibitor combinations (52% vs 41%, p = .02).
Conclusion: Compared with non-injection drug users, ABSSSI in injection drug users are more likely to involve streptococcal species and anaerobes and less likely to involve S. aureus. Injection drug users are more likely to be treated with β-lactamase inhibitor combinations; however, whether such broad-spectrum therapy is necessary should be further evaluated.
S. J. Moore, None
B. Mccollister, None
C. Saveli, None
S. Pawlowski, None
D. Perlman, None
W. Burman, None