November 30, 2015
1 min read

Majority of cellulitis cases originate from beta-hemolytic streptococci

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Most cases of cellulitis appear to be caused by beta-hemolytic streptococci, particularly Group A, Group C and Group G streptococci, according to recent findings.

“Knowledge of the predominance of [beta-hemolytic streptococci (BHS)] in most subgroups of cellulitis constitutes an important basis for empiric therapy,” the researchers wrote. “The importance of bacteria other than group A streptococci (GAS) in different clinical presentations of cellulitis is unclear, commonly leading to treatment with broad-spectrum antibiotics. Frequent use of broad-spectrum coverage even for mild cases as well as low frequency of de-escalation underscores the need for more precise knowledge of the etiology of cellulitis in different subgroups.” 

In the prospective study, researchers evaluated 203 adults who presented with suspected skin or soft tissue infections at Haukeland University Hospital, Norway, between September 2010 and August 2014. They collected and cultured blood samples and cutaneous swabs from wounds, abrasions, skin lesions and sterile cutaneous biopsied or surgical subcutaneous tissue samples.

BHS was the most prevalent etiology among all clinical subgroups, according to researchers. Seventy-two percent of cases had confirmed BHS, and 13% of cases had probable BHS.

“By combining serology, culture and response to penicillin treatment, our results suggest that more than 80% of the cases were of streptococcal origin, including the majority of patients without typical signs of streptococcal erysipelas, and those with purulence and comorbidities such as diabetes mellitus,” the researchers wrote.

Among BHS cases, Group C streptococci (GCS) and Group G streptococci (GGS) were more prevalent than GAS (36 vs. 22 cases) and were not confined to elderly patients or those with comorbidities as prior studies have shown. GCS/GGS infections were usually associated with the lower part of the body and GAS infections with the upper part of the body, possibly due to variations in the spread or pathogenicity in carriage sites such as the anus, toe webs and throat.

In addition, Staphylococcus aureus was isolated as a single pathogen in 24 patients, 14 of which (64%) had confirmed BHS etiology.

“This study confirms GAS and GCS/GGS as the primary causes of cellulitis,” the researchers concluded. “This includes not only erysipelas, but also deeper cellulitis, overlapping conditions and cases with S. aureus cultured from cutaneous swabs.” – by Jen Byrne

Disclosure: The researchers report no relevant disclosures.