Microbiology of the infected recurrent sacrococcygeal pilonidal sinus.

The aim of the present retrospective single centre study was to define the changes in the microbiological flora of the recurring sacrococcygeal pilonidal sinus (PS). Microbiological findings of swab samples of abscess-forming PS from 2000 to 2010 were evaluated. Within this time span, 73 swab samples were taken from primary sacrococcygeal pilonidal sinus (pPS) and 23 swab samples of patients with recurring sacrococcygeal pilonidal sinus (rPS). Our results show a statistically significant shift of the bacterial flora towards the gram-positive range (P = 0·029) and a shift with tendency towards the aerobic range (P = 0·090). Pathogens of pPS are not always solely anaerobic or gram-negative, and those of rPS not always aerobic or gram-positive. Therefore, antibiosis preceding microbiological examination should cover both the aerobic and anaerobic bacteria as well as the gram-positive and the gram-negative spectrum.