Septic pulmonary emboli caused by Tsukamurella inchonensis: A case report

Tsukamurella Bacteremia in a Surgical Patient: Case Report and Review of the Literature

Background: Tsukamurella species were first isolated in 1941. Since then, 48 cases of Tsukamurella bacteremia have been reported, a majority of which were immunosuppressed patients with central venous catheters.A case is described and previous cases of Tsukamurella bacteremia are reviewed. Patients and Methods: A 70-year-old total parenteral nutrition (TPN)-dependent female with recurrent enterocutaneous fistula (ECF), developed leukocytosis one week after a challenging ECF takedown. After starting broad-spectrum antibiotic agents, undergoing percutaneous drainage of intra-abdominal abscess, and subsequent repositioning of the drain, her leukocytosis resolved. Blood and peripherally inserted central catheter (PICC) cultures grew Tsukamurella spp. The patient was discharged to home with 14 days of daily 2 g ceftriaxone, with resolution of bacteremia. Conclusions: Tsukamurella spp. are a rare opportunistic pathogen predominantly affecting immunocompromised patients, with central venous catheters present in most cases. However, there have been few reported cases in immunocompetent individuals with predisposing conditions such as end-stage renal disease and uncontrolled diabetes mellitus.

Systematic investigation of the emerging pathogen of Tsukamurella species in a Chinese tertiary teaching hospital

Tsukamurella species have been clinically regarded as rare but emerging opportunistic pathogens causing various infections in humans. Tsukamurella pneumonia has often been misdiagnosed as pulmonary tuberculosis due to its clinical presentation resembling tuberculosis-like syndromes. Tsukamurella species have also been confused in the laboratory with other phylogenetic bacteria, such as Gordonia. This study aimed to investigate the clinical, microbiological, and molecular characteristics; species distribution; and antimicrobial susceptibility of Tsukamurella species. Immunodeficiency and chronic pulmonary disease appeared to be risk factors for Tsukamurella pneumonia, and the presence of bronchiectasis and pulmonary nodules on imaging was highly correlated with this infection. The study confirmed that groEL (heat shock protein 60) and secA (the secretion ATPase) genes are reliable for identifying Tsukamurella species. Additionally, the ssrA (stable small RNA) gene showed promise as a tool for discriminating between different Tsukamurella species with the shortest sequence length. In terms of antimicrobial susceptibility, quinolones, trimethoprim/sulfamethoxazole, amikacin, minocycline, linezolid, and tigecycline demonstrated potent in vitro activity against Tsukamurella isolates in our study. The study also proposed a resistance mechanism involving a substitution (S91R) within the quinolone-resistance-determining region of the gyrA gene, which confers resistance to levofloxacin and ciprofloxacin. Furthermore, we found that disk diffusion testing is not suitable for testing the susceptibilities of Tsukamurella isolates to ciprofloxacin, imipenem, and minocycline. In conclusion, our systematic investigation may contribute to a better understanding of this rare pathogen. Tsukamurella species are rare but emerging human pathogens that share remarkable similarities with other mycolic acid-containing genera of the order Actinomycetales, especially Mycobacterium tuberculosis. Consequently, misdiagnosis and therapeutic failures can occur in clinical settings. Despite the significance of accurate identification, antimicrobial susceptibility, and understanding the resistance mechanism of this important genus, our knowledge in these areas remains fragmentary and incomplete. In this study, we aimed to address these gaps by investigating promising identification methods, the antimicrobial susceptibility patterns, and a novel quinolone resistance mechanism in Tsukamurella species, utilizing a collection of clinical isolates. The findings of our study will contribute to improve diagnosis and successful management of infections caused by Tsukamurella species, as well as establishing well-defined performance and interpretive criteria for antimicrobial susceptibility testing.

A Pediatric Case of Septic Pulmonary Embolism Caused by Tsukamurella paurometabola

We herein report a three-year-old boy with septic pulmonary embolism caused by Tsukamurella paurometabola bacteremia during chemotherapy for rhabdomyosarcoma. During the interval of chemotherapy, the patient was temporarily discharged with a peripherally inserted central venous catheter but was re-admitted to the hospital with a fever on the same day. A blood culture taken at the time of re-admission showed T. paurometabola. The patient had a persistent fever, and computed tomography performed on the ninth day showed septic pulmonary embolism. We stress the importance of being aware of the possibility of septic pulmonary embolism in patients with Tsukamurella bacteremia.

Bacterial Peritonitis Caused by Tsukamurella inchonensis in a Patient Undergoing Continuous Ambulatory Peritoneal Dialysis

Background

Tsukamurella is an environmental saprophyte that potentially causes various infections in humans. It has been reported to cause rare opportunistic infections in immunocompromised patients or patients with indwelling foreign bodies.

Case Presentation

We report a case of continuous ambulatory peritoneal dialysis (CAPD)-related peritonitis caused by Tsukamurella inchonensis (T. inchonensis). The patient was admitted to our hospital while demonstrating a cloudy peritoneal dialysate. Peritoneal fluid sample culturing yielded yellow-greyish, dry and membrane-like colonies. Gram staining showed straight, gram-positive rods. The organism was identified to be Tsukamurella species by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). It was then characterized to be homologous to T. inchonensis in the GenBank database by 16S Ribosomal RNA Sequencing. The strain was susceptible to quinolones, carbapenems and linezolid, but intermediately resistant to vancomycin in drug susceptibility testing. Eventually, the peritonitis was controlled with meropenem and the patient discharged from the hospital.

Conclusion

Here, we describe the first case of CAPD-related peritonitis caused by T. inchonensis in China. Importantly, T. inchonensis show resistance to cephalosporins and heterogeneous resistance to vancomycin, guideline-based empiric therapy occasionally fails. Further analyses of similar cases are required to understand the characteristics and formulate appropriate therapy regimen for T. inchonensis infections.

Catheter-related bloodstream infection caused by Tsukamurella ocularis: A case report

Tsukamurella spp. causes mainly bacteremia and central venous catheter-related bloodstream infections. To the best of our knowledge, there is no documented evidence that Tsukamurella ocularis causes catheter-related bloodstream infections like other species of Tsukamurella. We present a novel case of T. ocularis bacteremia in a 69-year-old woman with malignant cancer, wherein the patient was successfully treated with a peripherally inserted central venous catheter. We administered combination antimicrobial therapy to the patient, which was terminated only after confirming the absence of infection. We identified T. ocularis by sequencing three housekeeping genes that could not be identified using conventional mass spectrometry and 16S rRNA gene analysis.