Higher Groin C Avidum Colonization in Obese Patients After Hip Arthroplasty

Colonization of Cutibacterium avidum in the groin after implantation of hip arthroplasties may be associated with obesity, according to findings from a study recently published in Clinical Infectious Diseases. 

Anaerobes such as C avidum are commonly isolated bacteria with preferential colonization of sweat glands in moist areas, like the groin. Recently, C avidum has been increasingly isolated from hip periprosthetic joint infections after implantation of hip arthroplasties with an anterior surgical approach.

The anterior surgical approach is in close approximation to the groin and represents a recent change from a lateral transgluteal approach.  

Therefore, this prospective study evaluated whether skin colonization with C avidum differs between the anterior and the lateral thigh as areas of surgical incision fields. Additionally, the study explored whether obese patients were at risk for colonization of C avidum in the skin folds of the groin, facilitating bacterial entry into the nearby incisions. 

From February to June 2017 at the Department of Orthopedics of the University Hospital Balgrist, skin scrapings from the groin and the anterior and lateral thigh in 65 patients undergoing primary hip arthroplasty were analyzed. Swabs were plated and anaerobically cultured for Cutibacterium spp. for at least 7 days. To explore associations between the colonization rate at different sites and body mass index (BMI), univariate logistic regression analysis was used. The median age for patients was 65 years, the median BMI was 26.2 kg/m², and 52.3% were female. 

Results showed hip colonization with Cutibacterium spp. in 67.7% of patients; of these patients, 50% were colonized with C acnes only, 34.1% were colonized with C avidum only, and 15.9% were colonized with both. Of the 21 patients (32.3%) with C avidum (15 monocolonized, 6 co-colonized with Propionibacterium acnes), colonization was found to be mainly at the groin (n=16, 24.6%), which was significantly higher than at the anterior (n=5; 7.7%; P=.009) and lateral thigh (n=6, 9.2%; P=.019). There was no significant difference in the incidence of C avidum colonization compared to C acnes or C granulosum between different sites. This suggests the need for further studies to evaluate current skin disinfection protocols to analyze adjustment for reducing colonization rates of C avidum. 

Patients colonized with C avidum did not differ in sex or age when compared to noncolonized patients. However, BMI was significantly higher in patients colonized with C avidum compared with noncolonized patients (30.1 kg/m² vs 25.6 kg/m²; P= .019). Furthermore, increased BMI was associated with colonization at the groin (odds ratio per unit BMI increase: 1.15; P= .014). No associations with sex, age, BMI, or localization were found with C acnes and C granulosum. 

Overall, the study authors conclude that “C. avidum colonization at the groin in obese patients may be a potential risk factor for contamination of the surgical field by using the anterior surgical approach in hip arthroplasty.” 

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Reference

Boni L, Kuster SP, Bartik B, Zbinden R, Zingg PO, Achermann Y. Cutibacterium avidum colonization in the groin is associated with obesity: a potential risk factor for hip periprosthetic joint infection (PJI) [published online May 9, 2018]. Clin Infect Dis. doi: 10.1093/cid/ciy379 

This article originally appeared on Infectious Disease Advisor