To the Editors: Serratia is a Gram-negative, rod-shaped, usually motile, facultative anaerobic, nonspore-forming pathogen belonging to the Yersiniaceae family of the Enterobacterales.1 It is frequently seen in the pediatric age group as nosocomial outbreaks in intensive care units; it can present as late-onset sepsis, pneumonia, meningitis, conjunctivitis, and urinary tract infection.2–4 Serratia arthritis, however, is rarely seen in all age groups.5 A case of Serratia arthritis detected after atypical trauma in a completely healthy young adult is presented. A 16-year-old male sheep farmer, 4 days before presentation, injected 150 sheep with the same syringe and then stabbed his left knee with the syringe. Forty-eight hours after the trauma, he presented to the district state hospital with swelling in his left knee. Due to the absence of an orthopedic specialist at the hospital, he was admitted to the pediatric ward without examination and started on systemic ceftriaxone treatment. At the 48th hour of treatment, fever and hypotension were added to the swelling in the left knee, and the patient was referred to us and admitted to the pediatric infectious diseases ward. On examination, he had a fever (39.2°C), blood pressure 86/55 mm Hg, cardiac pulse: 120/min, and there was an increase in diameter, erythema, and fluctuation in the left knee. Blood tests revealed a white blood cell count of 11,950/µL (85.6% neutrophils), a C-reactive protein (CRP) value of 254 mg/dL, and an erythrocyte sedimentation rate of 42 mm/hour. A superficial ultrasound was performed on the patient’s left knee. A mildly dense fluid collection up to 2.5 cm deep was observed in the suprapatellar bursa and joint space of the left knee. Contrast-enhanced magnetic resonance imaging of the left knee showed moderately increased fluid levels in the suprapatellar bursa and joint space, reported as diffuse contrast enhancement in the synovium (Fig. 1). The patient was consulted with orthopedics. Intra-articular aspiration was performed; the white blood cell count in the joint fluid was 47,510/µL (85.6% neutrophils). Serratia marcescens was detected in the polymerase chain reaction panel of the joint fluid. There was no growth in the joint fluid and blood cultures. The patient was consulted with orthopedics three times for intra-articular lavage and drainage, but intra-articular lavage was not performed. Piperacillin-tazobactam therapy was initiated. The fever subsided after 48 hours of treatment. During the second week of treatment, the patient had elevated acute phase reactants and minimal intra-articular fluid on ultrasound scans. Total treatment continued systemically for 21 days. At the end of treatment, no effusion was detected on ultrasound of the left knee, and the patient was discharged without sequelae.FIGURE 1.: Moderately increased fluid values in the suprapatellar bursa and joint space, with diffuse contrast retention in the synovium.Serratia species, especially Serratia marcescens, are important human pathogens. Although growth is observed in culture methods, 16S rRNA gene sequencing can enable better identification of Serratia species.6 As we were the second center the patient visited, and due to prior systemic antibiotic use, no growth was detected in the aspirate culture; however, the causative agent was identified using a polymerase chain reaction panel. In cases of Serratia arthritis reported in the 1970s, systemic lupus erythematosus and heroin use were indicated as risk factors.7–9 In our case, septic arthritis developed after trauma caused by an animal stabbing itself in the knee with a vaccination needle. Treatment for Serratia arthritis is recommended to be intra-articular arthroscopic lavage or open surgery and antibiotic therapy.9–12 Antibiotic selection should be based on culture and antibiogram.5 Due to the chromosomal AmpC β-lactamase carried by Serratia spp., the use of piperacillin-tazobactam or carbapenem is recommended for treatment.13 Empirical treatment with piperacillin-tazobactam via long infusion was initiated in our patient. Although the culture was negative, treatment with the current agent was continued due to the good clinical response. The patient was discharged without sequelae after a total of 3 weeks of systemic treatment.
Asuman Akar (Thu,) studied this question.