Microbiology and Predictors of Gram-Negative Infections in Persons Who Inject Drugs with Injection-Related Infections Requiring Hospitalization

Document Type

Conference Proceeding

Publication Date

11-27-2023

Publication Title

Open Forum Infect Dis

Keywords

adult, adverse device effect, aged, antimicrobial stewardship, bacteremia, bacterial arthritis, bacterial growth, bacterial infection, chi square distribution, cohort analysis, conference abstract, controlled study, drug therapy, drug use, endocarditis, epidural abscess, female, Gram negative infection, Gram positive bacterium, hospitalization, human, infection, infective endocarditis, injection drug user, intravenous drug administration, lower limb, major clinical study, male, medical record review, methicillin resistant Staphylococcus aureus, methicillin susceptible Staphylococcus aureus, nonhuman, osteomyelitis, overtreatment, retrospective study, risk factor, soft tissue infection

Abstract

Background. Intravenous drug use predisposes users to life-threatening bacterial infections primarily caused by gram-positive organisms. Studies have seen an uptrend in gram-negative injection-related infections in persons who inject drugs (PWID). Therefore, this study aimed to assess the microbiology of injection-related infections in PWID and evaluate risk factors that may predispose these patients to infections caused by gram-negative organisms. Methods. This retrospective chart review of adult PWID hospitalized with an injection-related infection (skin & soft tissue infection, bacteremia, septic arthritis, endocarditis, epidural abscess, and osteomyelitis) included patients aged >18 years with bacterial growth on specimens collected within 72 hours of admission from September 1, 2021, to March 31, 2022. Data analysis utilized descriptive statistics, chi-square tests, and Mann-Whitney U tests where appropriate. Results. A total of 259 patients were included in the study. 243 (93.8%) patients grew gram-positive organisms, while only 16 (6.2%) grew gram-negative organisms. The majority of patients were male (60%), the median age was 38 (IQR [33-44]), and 10% had a prior infection with MRSA. The distribution of injection-related infections included SSTIs (79.9%), bacteremia (34.7%), septic arthritis (12%), infective endocarditis (10.4%), osteomyelitis (8.5%), and epidural abscess (3.5%). The most commonly observed organisms were MRSA (36%), S. pyogenes (43%), and MSSA (9%). The gram-negative organisms isolated are shown in Figure 1. Approximately 84% of patients received overtreatment with an anti-pseudomonal agent; however, only 2% required its use. SSTIs with lower extremity involvement were found to be associated with gram-negative infections within this cohort, as shown in Table 1. Conclusion. In this study, despite less than 10% of patients growing gramnegative organisms on culture, approximately 80% received gram-negative treatment. Knowledge of the microbiology of infections in PWID can aid prescribers in optimizing empiric therapy for injection-related infections and preserving the core principles of antimicrobial stewardship.

Volume

10

Issue

Suppl 2

First Page

S962

Last Page

S963

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