Rhodococcus equi venous catheter infection: a case report and review of the literature

A Rare Presentation of Rhodococcus Equi Bacteremia as a Result of Right Upper Arm Cellulitis: A Case Report and Literature Review

Rhodococcus equi is an emerging opportunistic pathogen in immunocompromised patients. Owing to its resemblance to Mycobacterium, Nocardia, and Corynebacterium, R. equi is frequently misdiagnosed as a contaminant, which can result in treatment delays. A 65-year-old man with a history of end-stage renal disease (ESRD) presented to the emergency room with pain and increased swelling in his right upper extremity. Shortly after he arrived in the emergency room, his condition deteriorated. Intravenous vancomycin was administered after collecting blood cultures. The blood cultures grew Rhodococcus equi, and oral azithromycin and oral rifampin were added for a 14-day course of treatment. The patient recovered without any further complications and was subsequently discharged home.  R. equi is a partially acid-fast actinomycete that spreads through contact with grazing animals and contaminated soil. R. equi invades macrophages to survive and causes infection within a host. In this particular case, the patient worked on a farm taking care of goats. He was exposed to the bacteria after falling and sustaining multiple lacerations to the right arm. This case is unique due to the development of bacteremia with R. equi, an uncommon cause of bacteremia that led to cardiopulmonary arrest. The treatment with oral azithromycin combined with oral rifampin and intravenous vancomycin was effective for the complete resolution of the infection.

Bloodstream infection by Rhodococcus corynebacterioides in a pediatric patient diagnosed with high-risk retinoblastoma

Rhodococcus is a pathogen that is known to cause infections in animals and humans, mainly in cases of immunocompromised patients. A case of a pediatric cancer patient suffering from a bloodstream infection caused by Rhodococcus corynebacterioides was described in this work. Gram positive rods were isolated from blood cultures. The target bacterium was identified using a combination of biochemical tests, the MALDI-TOF mass spectrometry technique, and the analysis of the 16S rRNA sequence. Moreover, an antimicrobial susceptibility test was performed using the E-test. The isolated bacterium was identified as R. corynebacterioides. The 3-year-old patient was successfully treated with vancomycin and meropenem. This is the first published report of R. corynebacterioides in a pediatric patient diagnosed with retinoblastoma that developed a bloodstream infection. R. corynebacterioides should be considered among the opportunistic infectious agents affecting pediatric cancer patients.

Acquisition and Development of the Extremely Preterm Infant Microbiota Across Multiple Anatomical Sites

OBJECTIVES

Microbial communities influencing health and disease are being increasingly studied in preterm neonates. There exists little data, however, detailing longitudinal microbial acquisition, especially in the most extremely preterm (<26 weeks' gestation). This study aims to characterize the development of the microbiota in this previously under-represented cohort.

METHODS

Seven extremely preterm infant-mother dyads (mean gestation 23.6 weeks) were recruited from a single neonatal intensive care unit. Oral and endotracheal secretions, stool, and breast milk (n = 157 total), were collected over the first 60 days of life. Targeted 16S rRNA gene sequencing identified bacterial communities present.

RESULTS

Microbiota of all body sites were most similar immediately following birth and diverged longitudinally. Throughout the sampling period Escherichia, Enterococcus, Staphylococcus, and an Enterobacteriaceae were dominant and well dispersed across all sites. Temporal divergence of the stool from other microbiota was driven by decreasing diversity and significantly greater proportional abundance of Bifidobacteriaceae compared to other sites.

CONCLUSIONS

Four taxa dominated all anatomical sampling sites. Rare taxa promoted dissimilarity. Cross-seeding between upstream communities and the stool was demonstrated, possibly relating to buccal colostrum/breast milk exposure and indwelling tubes. Given the importance of dysbiosis in health and disease of extremely preterm infants, better understanding of microbial acquisition within this context may be of clinical benefit.

Acquisition and Development of the Extremely Preterm Infant Microbiota Across Multiple Anatomical Sites

OBJECTIVES

Microbial communities influencing health and disease are being increasingly studied in preterm neonates. There exists little data, however, detailing longitudinal microbial acquisition, especially in the most extremely preterm (<26 weeks' gestation). This study aims to characterize the development of the microbiota in this previously under-represented cohort.

METHODS

Seven extremely preterm infant-mother dyads (mean gestation 23.6 weeks) were recruited from a single neonatal intensive care unit. Oral and endotracheal secretions, stool, and breast milk (n = 157 total), were collected over the first 60 days of life. Targeted 16S rRNA gene sequencing identified bacterial communities present.

RESULTS

Microbiota of all body sites were most similar immediately following birth and diverged longitudinally. Throughout the sampling period Escherichia, Enterococcus, Staphylococcus, and an Enterobacteriaceae were dominant and well dispersed across all sites. Temporal divergence of the stool from other microbiota was driven by decreasing diversity and significantly greater proportional abundance of Bifidobacteriaceae compared to other sites.

CONCLUSIONS

Four taxa dominated all anatomical sampling sites. Rare taxa promoted dissimilarity. Cross-seeding between upstream communities and the stool was demonstrated, possibly relating to buccal colostrum/breast milk exposure and indwelling tubes. Given the importance of dysbiosis in health and disease of extremely preterm infants, better understanding of microbial acquisition within this context may be of clinical benefit.

Aerobic Actinomycetes of Clinical Significance

The group of Gram-positive bacillary organisms broadly known as "aerobic actinomycetes" consists of heterogeneous and taxonomically divergent genera. They are found in a wide variety of natural and man-made environments but are rarely considered a part of the normal human flora, with infections normally originating from exogenous sources. An extensive number of genera have been described, but only a minority of these has been associated with human or veterinary health. The association with human disease is usually of an opportunistic nature, either through accidental means of inoculation or through involvement with immunocompromising conditions in the host. They cause a wide spectrum of diseases in humans, which may differ greatly between the genera and even between species, but which also may have a great amount of overlap. The occurrence of such infections is probably greater than appreciated, since many may go unrecognized. Etiologic prevalence of specific genera and species varies geographically within the United States and worldwide. Traditional phenotypic identification methods for separation of the many genera and species of aerobic actinomycetes have found great difficulties. Recent use of chemotaxonomic analyses and emerging technologies such as molecular analysis of nucleic acids, and more recently proteomics for identification to the genus/species level, has provided a far more robust technique to understand the organisms' relatedness, distribution, epidemiology, and pathogenicity in humans.

Rhodococcus equi granulomatous mastitis in an immunocompetent patient

A 37-year-old immunocompetent woman was evaluated for progressive swelling of her left breast. Magnetic resonance imaging (MRI) showed multiple hypo-intense solid lesions and could not exclude breast cancer. Tissue biopsy was suggestive of granulomatous mastitis without any evidence of malignancy. Culture of the specimen in brain heart infusion broth grew Rhodococcus equi. The patient responded well to combination therapy with ciprofloxacin and azithromycin, and the lesions regressed in follow-up MRI. To the best of our knowledge, this is the first report of R. equi granulomatous mastitis. Accurate identification of this rare pathogen is necessary to provide appropriate treatment in granulomatous mastitis.

Rhodococcus bacteremia in cancer patients is mostly catheter related and associated with biofilm formation

Rhodococcus is an emerging cause of opportunistic infection in immunocompromised patients, most commonly causing cavitary pneumonia. It has rarely been reported as a cause of isolated bacteremia. However, the relationship between bacteremia and central venous catheter is unknown. Between 2002 and 2010, the characteristics and outcomes of seventeen cancer patients with Rhodococcus bacteremia and indwelling central venous catheters were evaluated. Rhodococcus bacteremias were for the most part (94%) central line-associated bloodstream infection (CLABSI). Most of the bacteremia isolates were Rhodococcus equi (82%). Rhodococcus isolates formed heavy microbial biofilm on the surface of polyurethane catheters, which was reduced completely or partially by antimicrobial lock solution. All CLABSI patients had successful response to catheter removal and antimicrobial therapy. Rhodococcus species should be added to the list of biofilm forming organisms in immunocompromised hosts and most of the Rhodococcus bacteremias in cancer patients are central line associated.