A Chinese patient with peritoneal dialysis-related peritonitis caused by Gordonia terrae: a case report

A 52-year-old man was diagnosed with uraemia at a local hospital in February 2013. He was treated using haemodialysis while in the hospital and with peritoneal dialysis after discharge. His serum creatinine concentration was 1000 μmol/L, showing two reduced renal volume. The patient was also diagnosed with chronic obstructive pulmonary disease, grade 3 hypertension (high-risk), and cardiac insufficiency. Starting in June 2015, the patient reported experiencing epigastric pain during the peritoneal dialysis, which was exacerbated during inspiration, relieved during dialysis fluid removal, and absent during non-dialysis periods. The dialysis fluids were smooth and accompanied by floccule.

On November 17, 2015, the patient experienced bloody ascites, swelling of both lower limbs, and asthma after playing sports and was admitted to our hospital. A physical examination revealed a body temperature of 38.0 °C, a respiratory rate of 22 breaths/min, a pulse of 110 beats/min, and blood pressure of 130/63 mmHg. The patient showed clear consciousness, but he exhibited facial signs of chronic anaemia, distension of the jugular vein, barrel chest, mild swelling of both lower limbs, wheezing in both lungs, an expanded heart boundary on two sides, abdominal wall tension, positive pressure at the navel, and no rebound tenderness. Laboratory testing revealed a white blood cell count of 3.4 × 10⁹/L, a procalcitonin level of 2.69 ng/mL, a B-type natriuretic peptide level of 460 pg/mL, a prothrombin time of 14.5 s, and a D-dimer level of 2,127 ng/mL. Routine testing of the peritoneal fluid revealed a slightly muddy appearance with a specific gravity of 1.018, weak positive results in the Rivalta test, a white blood cell count of 510 × 10⁶/L (mononuclear cells: 40%, multinuclear cells: 60%), a red blood cell count of 2,980 × 10⁶/L, and positive results for coagulability.

The patient’s peritoneal fluid was submitted for culturing, and the patient received initial treatment using intravenous cefazolin, which was changed to intraperitoneal ceftazidime and vancomycin on November 19. On November 23, the patient’s body temperature was 36.5 °C. He reported that his chest congestion and stomach ache were relieved, and the dialysis fluid appeared smooth and clear. The patient and his relatives insisted that he be discharged, despite our informing them that the culture results were incomplete, the infection might not be controlled, and the patient might experience recurrence of the peritonitis and septicopyaemia. Unfortunately, a telephone follow-up with the patient’s relatives revealed that he had not received continued treatment after his discharge and had died in February 2016. The cause of death was multiorgan failure.

On November 19, 2015, the patient’s peritoneal fluid was aseptically collected into aerobic blood culture bottles (BD, USA) and sent to a clinical laboratory, where it was cultured using the Bactec^TM 9120 blood culture system (BD, USA). After culturing for 51.76 h, a positive result was observed, and the culture fluid was directly smeared to identify gram-positive bacilli. The fluid was also transferred to blood agar (Zhengzhou Autobio) and chocolate agar plates (Tianjin Jinzhang), which were incubated at 35 °C with 5% CO₂. There were no visible colonies after 24 h of culturing, although both plates exhibited small light-brown colonies after 48 h of culturing. The colonies were positive in the catalase test. After 72 h on the chocolate agar plate and 6 days on the blood agar plate, the colonies were dry, cracked, elevated, and light brown in colour (Figs. 1 and 2). Figures 3 and 4 show that the colonies were confirmed to be gram-positive bacilli with positive, weak acid-fast staining. Additional testing using the MicrolexLT/SH mass spectrometer (Bruker) identified the strain as G. rubropertincta with a score of 1.702. However, a 16S rRNA sequence analysis was also performed at the Shanghai Sangon Company, using the following primers: 27 F (5′-GAGTTTGATCCTGGCTCAG-3′) and 1492R (5′-AAGGAGGTGATCCAGCCGCA-3′) [1]. After Blast alignment, we observed that the bacteria were 99% similar to the sequence of G. terrae EY-T12 (GenBank: KR476419.1). The phylogenetic tree of the 20160601 isolate is shown in Fig. 5.

An antimicrobial susceptibility testing was performed using the E-test (Zhengzhou Autobio), in which in the McFarland and M-H plates (Tianjin Jinzhang) are adjusted to 0.5 and incubated at 35 °C with 5% CO₂ for 48 h. The results from the patient described in this report and from those in previous studies are summarized in Table 2. The strains in the previous studies were also tested using the E-test after 48 h of incubation. The isolate from the present report was resistant to ceftazidime and susceptible to penicillin, ampicillin, amikacin, erythromycin, ceftriaxone, imipenem, gentamicin, and vancomycin.