Development and validation of a new quantitative reverse transcription PCR assay for the diagnosis of human sporotrichosis

Sporotrichosis is an emergent public health problem. The mycological diagnosis of this infection is based on culture, which is fastidious and may represent a biohazard for technicians. Although not widely implemented in routine diagnosis, molecular methodologies are fast, have good accuracy, and can be easily standardized, aiding in the early diagnosis of neglected mycoses. This study aimed at implementing a new pan-Sporothrix quantitative reverse transcription PCR (RT-qPCR) assay, and then validating it on clinical samples from confirmed human sporotrichosis cases. Sixty-eight human samples with culture-confirmed diagnostic of sporotrichosis were collected from 64 patients followed at a Brazilian reference center for endemic mycoses. These samples were submitted to whole nucleic acids extraction, followed by a RT-qPCR protocol. The limit of detection was 244 fg, the efficiency was 2.0 (100%), and the assay could amplify the genetic material of the three major clinically relevant species of the genus Sporothrix. Among the 68 samples analyzed, 62 were positive in RT-qPCR, showing an overall sensitivity of 91.18%, which variated according to the type of biological sample: 96.72% in skin samples (n = 61), 100% in respiratory (n = 3), whereas all cerebrospinal fluid specimens (n = 4) were negative. The specificity was 100% when tested in 25 samples from patients with other mycoses and tuberculosis. In addition, DNA from 93 fungal species did not yield positive results, confirming the high specificity of this test. Our RT-qPCR presented high sensitivity and specificity, representing an excellent tool for a fast and reliable diagnosis of human sporotrichosis.

Risk factors for the environmental spread of different multidrug-resistant organisms: a prospective cohort study

BACKGROUND

Substantial scientific evidence shows that contamination of environmental surfaces in hospitals plays an important role in the transmission of multidrug-resistant organisms (MDROs). To date, studies have failed to identify the risk factors associated with environmental contamination.

AIM

To evaluate, compare, and identify factors associated with environmental contamination around carriers of different MDROs.

METHODS

This was a prospective cohort study from May 2018 to February 2020. A total of 125 patients were included, having been admitted to Avicenne Hospital and Hotel Dieu de France de Beyrouth Hospital who were faecal carriers of MDROs (extended-spectrum β-lactamase-producing Enterobacterales (ESBL-PE), carbapenemase-producing Enterobacterales (CPE), vancomycin-resistant enterococci (VRE)). For each patient, quantification of MDRO in stool was undertaken, plus a qualitative evaluation of the presence of MDRO in six different environmental sites; and clinical data were collected.

FINDINGS

MDROs comprised ESBL-PE (34%), CPE (45%), and VRE (21%). The most frequent MDRO species was Escherichia coli. Contamination of at least one environmental site was observed for 22 (18%) patients. Only carriage of VanA was associated with a significantly higher risk of dissemination. Having a urinary catheter, carriage of OXA48 and E. coli were protective factors against environmental contamination. There were no significant differences in environmental contamination between E. coli and other Enterobacterales or between ESBL-PE and CPE.

CONCLUSIONS

Hospital environmental contamination rates are substantially higher for patients with VRE, compared to the low environment dissemination rates around ESBL-PE and CPE. Further studies on a larger scale are needed to confirm the validity of our findings.