Septic arthritis is classified among the acute emergencies of joint diseases. Gram-positive cocci are responsible in 75-80% of the cases, while Gramnegative bacilli may be the etiological agents in case of compromised immunity, intravenous drug abuse, advanced age, or iatrogenic infections. Cases of posttraumatic septic arthritis due to Gram-negative bacilli in immunocompetent patients are reported in the literature. In this paper we present a severe septic arthritis due to Serratia marcescens in a 43-year-old man with multiple trauma, right patellar and femoral condyle fracture after a traffic accident, three days after an irrigation and debridement procedure was performed. The surgical procedure had to be repeated four times while he was receiving medical treatment. A literature search in PubMed using the keywords "Serratia marcescens and septic arthritis" on October 10 th 2017, we found 37 articles, of which 18 were case reports or case series. Of those 18 articles, seven cases were hospital-acquired, five were in intravenous drug users, two were trauma related, one was concomitant with rheumatoid arthritis, one was in a neonate, one was due to intra-articular injection, and one article described an epidemic due to usage of contaminated benzalkonium chloride solution as an antiseptic. We also found a case by searching Turkish Medline reported in a ten-week-old baby with Escobar syndrome. In our case, although hospital-acquired infection cannot be ruled out, we believe that this was a community-acquired infection due to contamination of the open dirty wound, as the irrigation procedure was done in sterile operating room conditions and no other such case has ever been identified. As prompt diagnosis and treatment is critical in prognosis of septic arthritis, we emphasize the possible role of Gram-negative bacilli in posttraumatic cases. Keywords: Septic arthritis, Serratia marcescens, posttraumatic, generic antibiotics, ertapenem Septik artrit, eklemle ilgili acil hastalıklar arasında sınıflandırılır. Erken tanı ve tedavi prognoz açısından oldukça önem taşır. Tüm olgularda en sık görülen etkenler %75-80 oranında Gram-olumlu koklardır. Ancak immün yetmezlik, damar içi ilaç alışkanlığı, ileri yaşlar veya iyatrojenik olgularda Gram-olumsuz basiller de etken olabilirler. Literatürde immünkompetan hastalarda da travma sonrası gelişen Gram-olumsuz basillere bağlı artritler bildirilmektedir. Bu yazıda trafik kazası sonucu multitravma, sağ patella ve sağ femoral kondil kırığı ile başvuran 43 yaşındaki erkek olguda debridman ve yıkama işlemi sonrasında üçüncü gün gelişen, Serratia marcescens'e bağlı şiddetli septik artrit olgusu sunulmuştur. Antibiyoterapi alırken cerrahi yıkama işleminin biri açık artrotomi olmak üzere dört kez tekrarlanması gerekmiştir. PubMed'de 10 Ekim 2017'de anahtar kelime olarak "Serratia marcescens ve septic arthritis" kullanılarak yapılan taramada 37 adet makale bulunmuş ve olgu bildiren 18 makale incelenmiştir. Makalelerin yedisi hastane kaynaklı, beşi damar içi ilaç alışkanlığı, ikisi travmay...