Primary retroperitoneal abscesses due to Rhodococcus equi in a patient with severe nephrotic syndrome: successful antibiotic treatment with linezolid and tigecycline

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.

Rhodococcus hoagii bloodstream infection in an allogeneic hematopoietic stem cell transplantation patient: Case report and review of literature

We report a case of bloodstream infection caused by R. hoagii in a woman with acute myeloid leukemia, 37-years-old, who received an allogeneic hematopoietic stem cell transplant. She developed cutaneous and gastrointestinal tract graft versus host disease, respectively on day 29 and day 69. On day 157 she developed to acute severe respiratory failure. Rhodococcus sp was identified by MALDI-TOF and 16S rRNA sequencing from blood culture as Rhodococcus hoagii. The patient was a nurse that lived in urban areas, and stated no recent trips to countryside areas neither contacted with animals. Despite of the treatment with antibiotics with action against R. hoagii such as linezolid and meropenem the patient evolved to multiorgan dysfunction and death. Our case-report emphasizes the importance of early diagnosis and the use of 16S rRNA sequencing to confirmed the identification of species of Rhodococcus infection.

Rare and persistent Rhodococcus equi infection in a diffuse large B cell lymphoma patient: case report and review of the literature

Rhodococcus equi (R. equi) is an uncommon gram positive organism. It is a rare but recognized pathogen in humans and has emerged as an important cause of morbidity and mortality among immunocompromised patients. Generally, R. equi infection needs combined treatment with effective antibiotics, and often requires the immune adjuvant therapy. Here we reported a 49-year-old man presented dyspnea with fever, skin ulcer for 5 months, and the final diagnosis was diffuse large B cell lymphoma with R. equi septicemia and pneumonia, the treatment was failure, the blood culture was always positive during the course of disease, though he was given combined treatment with effective antibiotics, perhaps the immune reconstitution or immune supportive treatment was more important.

Tigecycline : a critical safety review

INTRODUCTION

The emergence of multidrug-resistant (MDR) infections has been extensively observed worldwide and has become a priority issue over past decade. Tigecycline , a broad spectrum antibiotic covering against many MDR organisms, has been widely used. However, recent meta-analysis studies have raised a concern for its efficacy and safety. Reviewing tigecycline safety data would enhance the appropriate use of this medication.

AREAS COVERED

This article reviews the safety profile of tigecycline, including its side effects and drug interactions.

EXPERT OPINION

The increased mortality associated with tigecycline is not yet well understood. Based on current evidence, alternative options must be prioritized over tigecycline if available. When tigecycline use is warranted, vigilant observation to identify any breakthrough infections and careful monitoring of progression of the original infection are highly recommended. Considering a second agent (either for synergism or enhancing coverage) may be required.

Antibiotic failure in a renal transplant patient with Rhodococcus equi infection: an indication for surgical lobectomy

Rhodococcus equi is an animal pathogen that causes infrequent but challenging infections in immunocompromised individuals, few of which have been described in solid organ transplant recipients. Common clinical presentations include indolent cough, fever, and dyspnea, with necrotizing pneumonia and cavitation. We report a case of a dense right upper lung pneumonia with resultant R. equi bacteremia in a renal transplant recipient. Our patient initially responded to antibiotic treatment with resolution of bacteremia and clinical recovery, followed by interval progression in her right upper lobe consolidation on follow-up computed tomography scans. She underwent lobectomy for definitive therapy with resolution of symptoms. Lobectomy can be utilized in isolated infection after antibiotic failure with excellent clinical outcomes.

Disseminated Rhodococcus equi infection in HIV infection despite highly active antiretroviral therapy

BACKGROUND

Rhodococcus equi (R.equi) is an acid fast, GRAM + coccobacillus, which is widespread in the soil and causes pulmonary and extrapulmonary infections in immunocompromised people. In the context of HIV infection, R.equi infection (rhodococcosis) is regarded as an opportunistic disease, and its outcome is influenced by highly active antiretroviral therapy (HAART).

CASE PRESENTATION

We report two cases of HIV-related rhodococcosis that disseminated despite suppressive HAART and anti-rhodococcal treatment; in both cases there was no immunological recovery, with CD4+ cells count below 200/μL. In the first case, pulmonary rhodococcosis presented 6 months after initiation of HAART, and was followed by an extracerebral intracranial and a cerebral rhodococcal abscess 1 and 8 months, respectively, after onset of pulmonary infection. The second case was characterized by a protracted course with spread of infection to various organs, including subcutaneous tissue, skin, colon and other intra-abdominal tissues, and central nervous system; the spread started 4 years after clinical resolution of a first pulmonary manifestation and progressed over a period of 2 years.

CONCLUSIONS

Our report highlights the importance of an effective immune recovery, despite fully suppressive HAART, along with anti-rhodococcal therapy, in order to clear rhodococcal infection.