A national study of more than 24,000 adults hospitalized after firearm injuries has found that approximately 5 percent developed a bacterial infection, with most cases identified during the initial hospital stay rather than after discharge. The analysis, conducted by researchers at the University of Maryland School of Medicine (UMSOM), offers one of the largest examinations to date of infection patterns among firearm-injury patients in the United States. The findings were published August 3 in JAMA Network Open as a research letter.
Firearm injuries are widely recognized for causing substantial trauma to organs, blood vessels, bones, and soft tissue, but the infectious complications that follow these wounds have received comparatively little large-scale study. To investigate the issue, researchers analyzed administrative and clinical data from 24,024 adults treated at 323 hospitals between January 2019 and May 2021. The dataset allowed the team to examine infections diagnosed during hospitalization and during a 90-day period after discharge.
Overall, 1,236 patients developed a documented bacterial infection, representing about 5 percent of the study population. The timing of these infections was a central finding. Most occurred during the initial hospitalization, while only 1.3 percent of patients experienced an infection during the 90-day follow-up period after leaving the hospital. This pattern suggests that the greatest infectious risk is concentrated in the acute phase of treatment, when patients are undergoing emergency procedures, intensive monitoring, and repeated interventions.
The risk was not distributed evenly among patients. Individuals who underwent operations involving the head, neck, spine, liver, or lower abdomen were more likely to develop bacterial infections than those who did not require these procedures. Surgical treatment in these areas can involve complex anatomy, extensive tissue disruption, contamination of normally sterile body compartments, and prolonged exposure to hospital-based procedures. Injuries affecting the gastrointestinal tract or other organs may also release bacteria into surrounding tissues, creating conditions that can lead to abscesses, bloodstream infections, or infections at surgical sites.
The researchers identified Escherichia coli, Staphylococcus aureus, and enterococci among the most frequently recorded organisms. These bacteria are associated with different biological sources and clinical syndromes. E. coli commonly inhabits the intestinal tract and can cause infection when penetrating injuries disrupt the bowel or abdominal cavity. S. aureus, which can colonize the skin and nasal passages, is a frequent cause of wound and postoperative infections. Enterococci are also normal intestinal organisms but can become opportunistic pathogens in patients who have undergone major surgery or prolonged hospitalization.
The study also examined antibiotic exposure and found that patients who did not develop infections generally received relatively little antibiotic treatment. The finding is consistent with current efforts to avoid unnecessary preventive antibiotics in firearm-related injuries when there is no clear evidence of bacterial contamination or established infection. Antibiotics can reduce the risk of infection in selected circumstances, but indiscriminate use may promote antimicrobial resistance, disrupt the normal microbiome, and expose patients to adverse effects such as allergic reactions or Clostridioides difficile infection.
“Firearm injury is a recognized risk for bacterial infection, but no large studies have described how often they occur and which patients are most at risk,” said Jonathan D. Baghdadi, MD, PhD, senior author and an associate professor of epidemiology and public health at UMSOM. He and his colleagues developed an approach for identifying bacterial infections in observational and administrative datasets, where diagnostic information may be recorded through billing codes, laboratory data, procedures, and clinical documentation rather than through a single standardized test.
Although infection was associated with serious complications of recovery, the researchers did not find that bacterial infection was independently linked to a higher risk of death among patients who survived at least one night in the hospital. Mortality, however, represents only one measure of outcome. Infections can extend hospitalization, require additional surgery, delay wound healing, increase healthcare costs, and contribute to chronic pain, reduced mobility, and long-term disability. These effects may be particularly consequential for patients with injuries to the spine, head, or neck.
The authors emphasized that the study has important limitations. Administrative hospital records may contain incomplete clinical details, and some infections diagnosed outside participating hospitals may not have been captured during follow-up. The data also cannot establish that firearm injury characteristics or surgical procedures directly caused infection, because the analysis was observational and may have been influenced by differences in injury severity, treatment, and patient health. Even so, the size and geographic breadth of the dataset provide a broad view of bacterial complications after firearm injury and identify patients who may benefit from especially close surveillance.
Melike Harfouche, MD, MPH, an associate professor of surgery at UMSOM and a surgeon at the University of Maryland Medical Center, said the elevated risk among patients undergoing head, neck, and spine procedures underscores the importance of monitoring this vulnerable population for both early and delayed infections. The researchers hope their findings will support more precise clinical decision-making and provide a framework for future studies examining specific organisms, surgical procedures, antibiotic strategies, and long-term recovery after firearm injury.
Subject of Research: People
Article Title: Bacterial Infections in US Adults with Firearm Injuries
News Publication Date: 3 August 2026
Web References: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2852395 ; https://doi.org/10.1001/jamanetworkopen.2026.27109
References: JAMA Network Open, DOI: 10.1001/jamanetworkopen.2026.27109
Keywords: Gun violence; Microbial infections; Public health
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