Streptomyces thermovulgaris bacteremia in Crohn's disease patient

Identification of Streptomyces spp. in a clinical sample: always contamination? Results of a French Retrospective Study

Background

Streptomyces are environmental Gram-positive bacilli that can cause ubiquitous mycetoma and, more rarely, invasive infections. We describe the clinical relevance of Streptomyces spp. identified in human samples and characteristics of patients with invasive Streptomyces infections.

Methods

We conducted a retrospective (2006-2017) study of Streptomyces isolates identified in clinical samples in French microbiology laboratories. Streptomyces genus was confirmed by a specific 16S rRNA PCR and antibiotic susceptibility testing was performed by disk diffusion and trimethoprim-sulfamethoxazole MIC (E-test) if resistance was suspected. Patient characteristics, treatment and outcomes were collected. Invasive infection was defined as a positive culture from a sterile site with signs of infection but without cutaneous inoculation.

Results

Of 137 Streptomyces isolates, all were susceptible to amikacin (113/113) and linezolid (112/112) and 92.9% to imipenem (105/113). Using disk diffusion, 50.9% (57/112) of isolates were susceptible to trimethoprim-sulfamethoxazole but most of apparently-resistant isolates (25/36, 69.4%) tested by E-test were ultimately classified as susceptible. Clinical data were obtained for 63/137 (45.9%) isolates: 30 (47.6%) invasive infections, 8 (12.7%) primary cutaneous infections, 22 (34.9%) contaminations, 3 (4.7%) respiratory colonization. Patients with invasive infection were more frequently receiving corticosteroids than patients without invasive infection (11/30, 36.7% vs 2/25, 8.0%, P = 0.03) and at 6-months follow-up, 14 of them were cured, three had relapsed, four were dead and nine were lost to follow-up.

Conclusions

Half of the clinical samples that grew Streptomyces were from patients with invasive infection. In that case, antimicrobial therapy should include one or two antibiotics among linezolid, amikacin or imipenem.

Thermophilic and alkaliphilic Actinobacteria: biology and potential applications

Microbes belonging to the phylum Actinobacteria are prolific sources of antibiotics, clinically useful bioactive compounds and industrially important enzymes. The focus of the current review is on the diversity and potential applications of thermophilic and alkaliphilic actinobacteria, which are highly diverse in their taxonomy and morphology with a variety of adaptations for surviving and thriving in hostile environments. The specific metabolic pathways in these actinobacteria are activated for elaborating pharmaceutically, agriculturally, and biotechnologically relevant biomolecules/bioactive compounds, which find multifarious applications.

Leclercia adecarboxylata Bacteremia in a Patient with Ulcerative Colitis

Patients with inflammatory bowel disease (IBD) are a high risk population for bacteremia. Derangement in the mucosal architecture of the gastrointestinal (GI) tract and frequent endoscopic interventions in immunocompromised individuals are considered primary causes. Isolation of opportunistic microorganisms from the bloodstream of IBD patients has been increasingly reported in recent years. Leclercia adecarboxylata is a ubiquitous, aerobic, motile, gram-negative bacillus. The human GI tract is known to harbor this rarely pathogenic microorganism. There are only a few case reports of bacteremia with this microorganism; the majority are either polymicrobial or associated with immunocompromised patients. We describe a case of monomicrobial L. adecarboxylata bacteremia in a 43-year-old female who presented with bloody diarrhea. Colonoscopy revealed diffuse colonic mucosal inflammation with numerous ulcers, and histopathology revealed crypt abscesses. Following an episode of rectal bleeding, two sets of blood cultures grew L. adecarboxylata, which was treated with intravenous ceftriaxone. After a complicated hospital course, she was eventually diagnosed with ulcerative colitis and enteropathic arthritis, treated with intravenous methylprednisolone, mesalamine, and infliximab which resulted in resolution of her symptoms. In our previously immunocompetent patient, derangement of the gut mucosal barrier was the likely cause of bacteremia, yet performing endoscopic intervention may have contributed to bacterial translocation.

Central venous catheter-related Streptomyces septic thrombosis

Streptomyces species are part of the actinomycetes group. They have rarely been reported as a cause of invasive infection. We report a case of catheter-related Streptomyces bacteremia complicated by severe sepsis and septic thrombosis. We also present a brief review of the literature on Streptomyces bacteremia.