Abstract
RATIONALE: Comamonas kerstersii mainly causes intra-abdominal infections with favorable outcomes due to high antibiotic susceptibility. We report the first case of pneumonia caused by C Kerstersii, which promoted patient death, and a second urinary tract infection by C Kerstersii with extensive drug resistance. PATIENT CONCERNS: A 46-year-old male (Case 1) with craniocerebral injury underwent emergency decompressive craniectomy, but his condition deteriorated further and presented with discontinuous fever, small moist rales on both lungs, and respiratory failure. Retrospective average nucleotide identity (ANI) analysis of the genomic sequence of the sputum isolate identified it as C Kerstersii 12322-1, antimicrobial susceptibility testing (AST) revealed that it was sensitive to 18 of 21 tested antibiotics.An 82-year-old male (Case 2) with hypertrophic prostate experienced gradual obstruction during urination, and a urine test revealed WBC ++. Retrospective ANI analysis of the urine isolate identified it as C Kerstersii 121606, which was resistant to 18 of 21 tested antibiotics. DIAGNOSES: Case 1 was diagnosed empirically as pneumonia caused by C Kerstersii strain 12322-1 secondary to craniocerebral injury and confirmed by retrospective ANI analysis; case 2 was diagnosed empirically as urinary infection secondary to prostate hyperplasia caused by C Kerstersii strain 121606 confirmed by the retrospective ANI analysis. INTERVENTIONS: Case 1 was administered cefoxitin, cefodizime, imipenem-cilastatin sodium, and underwent comprehensive salvage management. Case 2 was administered doxycycline alone. OUTCOMES: Case 1 died partially because of untimely identification of the responsible bacteria-12322-1. Case 2 was cured even 121606 exhibited an extensive drug resistance feature. LESSONS: Except for intra-abdominal infections with good prognosis, we verified that C Kerstersii could also cause extra-abdominal infections, such as the first pneumonia case and urinary infection. It could promote patient death; actual infections were underestimated due to identification difficulties, posing a health threat due to the presence of extensive drug resistance.