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 polymerase chain reaction, and antibiotic susceptibility testing was performed by disk diffusion and trimethoprim-sulfamethoxazole minimum inhibitory concentration (E-test) if resistance was suspected. Patient characteristics, treatments, 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 the 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 = .03), and at 6-month follow-up, 14 of them were cured, 3 had relapsed, 4 were dead, and 9 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 1 or 2 antibiotics among linezolid, amikacin, or imipenem.

Acute Pericarditis: Aetiologic Diagnosis and Practical Aspect of the Management.

Pericarditis is an uncommon pathology that represents 0.1% of patients hospitalized for chest pain with a wide etiological spectrum and whose cause is uncommonly highlighted. In order to determine the incidence of specific acute microbiological or autoimmune pericarditis and identify subsets of patients with a higher incidence of specific etiologies; and analyze the conformity of the management of acute pericarditis according to the recommendations, a retrospective inclusion of all patients admitted to our hospital from January 2010 to December 2018 with the diagnosis of acute pericarditis was conducted. Data concerning clinical, paraclinical and treatment items were collected. Ninety-nine patients were included. Specific etiologic exams were completely conducted in 63.6% of the patients. There was no link between the decision to conduct etiology exams and the age, gender, a history of acute pericarditis or relapse. There was a trend between an elevated CRP and the realization of the kit. There was a statistically significant link between the achievement of etiologic exams and the presence of severity criteria or the presence of a pericardial effusion. An etiology was found in 52.4%, more frequently microbiological (viral and Mycoplasma pneumoniae). Approximately 85.9% of all patients were hospitalized. Treatment was in accordance with the recommendations in 76.8%. Despite the percentage of microbiological etiologies found, it does not impact the therapeutic strategy. The criteria for hospitalization must be better suited since half of those hospitalized after the european society of cardiology (ESC) 2015 recommendations had no need to be. However, monitoring after discharge is not clearly defined by learned societies.

Chitosan Films for Microfluidic Studies of Single Bacteria and Perspectives for Antibiotic Susceptibility Testing.

Single-cell microfluidics is a powerful method to study bacteria and determine their susceptibility to antibiotic treatment. Glass treatment by adhesive molecules is a potential solution to immobilize bacterial cells and perform microscopy, but traditional cationic polymers such as polylysine deeply affect bacterial physiology. In this work, we chemically characterized a class of chitosan polymers for their biocompatibility when adsorbed to glass. Chitosan chains of known length and composition allowed growth of Escherichia coli cells without any deleterious effects on cell physiology. Combined with a machine learning approach, this method could measure the antibiotic susceptibility of a diversity of clinical strains in less than 1 h and with higher accuracy than current methods. Finally, chitosan polymers also supported growth of Klebsiella pneumoniae, another bacterial pathogen of clinical significance.IMPORTANCE Current microfluidic techniques are powerful to study bacteria and determine their response to antibiotic treatment, but they are currently limited by their complex manipulation. Chitosan films are fully biocompatible and could thus be a viable replacement for existing commercial devices that currently use polylysine. Thus, the low cost of chitosan slides and their simple implementation make them highly versatile for research as well as clinical use.

Mycobacterium iranicum bacteremia and hemophagocytic lymphohistiocytosis: a case report.

BACKGROUND: Mycobacterium iranicum has recently been recognised as an opportunistic human pathogen. Although infectious conditions represent frequent triggers for hemophagocytic lymphohistiocytosis, non-tuberculous mycobacterial infections are rarely associated with this entity. To this date, M. iranicum infection has never been reported in France, has never been associated with hemophagocytic lymphohistiocytosis and has never been found to be multi-resistant on standardized antimicrobial susceptibility testing. CASE PRESENTATION: We report a case of a French Caucasian man with secondary hemophagocytic lymphohistiocytosis in the context of M. iranicum bacteraemia and Hodgkin's disease. We review available data concerning M. iranicum antimycobacterial susceptibility testing and treatment outcomes. We also review the association between hemophagocytic lymphohistiocytosis and non-tuberculous mycobacterial infections. CONCLUSION: Interpretation of M. iranicum positive cultures remains a clinical challenge and non-tuberculous mycobacterial infections need to be considered in secondary hemophagocytic lymphohistiocytosis differential diagnosis.