Rhodococcus equi Sepsis in a Renal Transplant Recipient: A Case Study

Pleural empyema with endobronchial mass due to Rhodococcus equi infection after renal transplantation: A case report and review of literature

BACKGROUND

Kidney transplantation is the best option for patients with end-stage renal disease. However, the need for lifelong immunosuppression results in renal transplant recipients being susceptible to various infections. Rhodococcus equi (R. equi) is a rare opportunistic pathogen in humans, and there are limited reports of infection with R. equi in post-renal transplant recipients and no uniform standard of treatment. This article reports on the diagnosis and treatment of a renal transplant recipient infected with R. equi 21 mo postoperatively and summarizes the characteristics of infection with R. equi after renal transplantation, along with a detailed review of the literature.

CASE SUMMARY

Here, we present the case of a 25-year-old man who was infected with R. equi 21 mo after renal transplantation. Although the clinical features at the time of presentation were not specific, chest computed tomography (CT) showed a large volume of pus in the right thoracic cavity and right middle lung atelectasis, and fiberoptic bronchoscopy showed an endobronchial mass in the right middle and lower lobe orifices. Bacterial culture and metagenomic next-generation sequencing sequencing of the pus were suggestive of R. equi infection. The immunosuppressive drugs were immediately suspended and intravenous vancomycin and azithromycin were administered, along with adequate drainage of the abscess. The endobronchial mass was then resected. After the patient's clinical symptoms and chest CT presentation resolved, he was switched to intravenous ciprofloxacin and azithromycin, followed by oral ciprofloxacin and azithromycin. The patient was re-hospitalized 2 wk after discharge for recurrence of R. equi infection. He recovered after another round of adequate abscess drainage and intravenous ciprofloxacin and azithromycin.

CONCLUSION

Infection with R. equi in renal transplant recipients is rare and complex, and the clinical presentation lacks specificity. Elaborate antibiotic therapy is required, and adequate abscess drainage and surgical excision are necessary. Given the recurrent nature of R. equi, patients need to be followed-up closely.

Rhodococcus equi bacteremia with necrotizing pneumonia and brain abscess in a newly diagnosed HIV patient in Saudi Arabia: A case report and review of literature

Rhodococcus equi is a Gram-positive coccobacillus that falls within the category of aerobic actinomycetes. The Rhodococcus genus belongs to the nocardioform bacteria group. This microorganism has been found in various settings, including natural environments, animals, and particularly in individuals with compromised immune systems, such as those living with HIV. Notably, there is an increasing number of reports concerning R. equi infections in transplant recipients and even individuals with a normally functioning immune system. Traditionally, R. equi has been primarily associated with pulmonary infections, but there is a growing body of evidence documenting its involvement in extrapulmonary infections. In this report, we present a case involving a newly diagnosed HIV patient who experienced R. equi -induced necrotizing pneumonia, bacteremia, and a brain abscess in newly diagnosed HIV patient. It is important to note that a direct Gram stain may potentially lead to misclassification of such microorganisms as contaminants. Microbiologists should therefore prioritize the careful examination of colony morphology, biochemical reactions, and consider the limitations of automated machine databases. Furthermore, they should correlate their identification findings with clinical data to ensure optimal patient care and management, especially in the context of an immunocompromised state.

Antimicrobial resistance spectrum conferred by pRErm46 of emerging macrolide (multidrug)-resistant Rhodococcus equi

Clonal multidrug resistance recently emerged in Rhodococcus equi, complicating the therapeutic management of this difficult-to-treat animal and human pathogenic actinomycete. The currently spreading multidrug-resistant (MDR) "2287" clone arose in equine farms upon acquisition, and co-selection by mass macrolide-rifampin therapy, of the pRErm46 plasmid carrying the erm(46) macrolides-lincosamides-streptogramins resistance determinant, and an rpoB^S531F mutation. Here, we screened a collection of susceptible and macrolide-rifampin-resistant R. equi from equine clinical cases using a panel of 15 antimicrobials against rapidly growing mycobacteria (RGM), nocardiae and other aerobic actinomycetes (NAA). R. equi -including MDR isolates- was generally susceptible to linezolid, minocycline, tigecycline, amikacin and tobramycin according to Staphylococcus aureus interpretive criteria, plus imipenem, cefoxitin and ceftriaxone based on Clinical & Laboratory Standards Institute (CLSI) guidelines for RGM/NAA. Ciprofloxacin and moxifloxacin were in the borderline category according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. Molecular analyses linked pRErm46 to significantly increased MICs for trimethoprim-sulfamethoxazole and doxycycline in addition to clarithromycin within the RGM/NAA panel, and to streptomycin, spectinomycin and tetracycline resistance. pRErm46 variants with spontaneous deletions in the class 1 integron (C1I) region, observed in ≈30% of erm(46)-positive isolates, indicated that the newly identified resistances were attributable to C1I's sulfonamide (sul1) and aminoglycoside (aaA9) resistance cassettes and adjacent tetRA(33) determinant. Most MDR isolates carried the rpoB^S531F mutation of the 2287 clone, while different rpoB mutations (S531L, S531Y) detected in two cases suggest the emergence of novel MDR R. equi strains.

Metagenomic Next-Generation Sequencing in Diagnosis of a Case of Pneumocystis jirovecii Pneumonia in a Kidney Transplant Recipient and Literature Review

Background

Despite the increasing incidences of Pneumocystis jirovecii pneumonia (PCP) in renal transplant recipients, diagnosis of PCP remains challenging due to its nonspecific clinical presentation and the inadequate performance of conventional diagnostic methods. There is a need for novel diagnostic methods.

Case Presentation

A 27-year-old woman developed acute pneumonia 4 months after renal transplantation. Blood tests revealed a low CD4 count, a normal 1,3-beta-D-glucan level and other changes typical of inflammatory responses. Chest imaging showed bilateral diffuse infiltrates. Microscopic examination of stained sputum and bronchoalveolar lavage fluid (BALF) smear specimens did not find Pneumocystis organisms. There was also no evidence for other pathogens known to cause pneumonia in various antibody and culture tests. Direct metagenomic next-generation sequencing (mNGS) analysis of a BALF specimen identified a large number of P. jirovecii reads, allowing to confirm the diagnosis of PCP. Following treatment with trimethoprim-sulfamethoxazole for two weeks, the patient was cured and discharged.

Conclusion

This case report supports the value of mNGS in diagnosing PCP, highlights the inadequate sensitivity of conventional diagnostic methods for PCP, and calls for the need to add PCP prophylaxis to the current Diagnosis and Treatment Guideline of Invasive Fungal Infections in Solid Organ Transplant Recipients in China.