Acid-fast bacteria as causative agents of skin and soft tissue infections: case presentations and literature review

ABSTRACT Acid-fast bacteria can be implicated in skin and soft tissue infections. Diagnostic identification can be challenging or not feasible by routine laboratory techniques, especially if there is no access to the Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) technology. Here, we present two cases of skin and soft tissue infections caused by two different acid-fast bacteria, Nocardia brasiliensis and Mycobacterium marinum. They both grew on Löwenstein-Jensen medium, Sabouraud agar medium and blood agar medium. Both bacteria appeared acid-fast by Ziehl-Neelsen stain and Gram-positive by Gram stain. The identification was performed by MALDI-TOF MS and gene analysis. N. brasiliensis and nontuberculous mycobacterium M. marinum represent rare pathogens that cause severe skin and soft tissue infections. Failure to identify the causative agent and subsequent inappropriate or inadequate treatment may lead to severe complications or even disseminated disease, especially in immunocompromised individuals.

Increased incidence of candidemia in critically ill patients during the Coronavirus Disease 2019 (COVID-19) pandemic

Abstract Background Patients with severe Coronavirus Disease 2019 (COVID-19) are treated with corticosteroids. Aim We aimed to evaluate the role of corticosteroid treatment in candidemia development during the COVID-19 pandemic. Methods This retrospective study was conducted in a Greek ICU, from 2010 to August 2021, encompassing a pre-pandemic and a pandemic period (pandemic period: April 2020 to August 2021). All adult patients with candidemia were included. Results During the study period, 3,572 patients were admitted to the ICU, 339 patients during the pandemic period, of whom 196 were SARS-CoV-2-positive. In total, 281 candidemia episodes were observed in 239 patients, 114 in the pandemic period. The majority of candidemias in both periods were catheter-related (161; 50.4%). The incidence of candidemia in the pre-pandemic period was 5.2 episodes per 100 admissions, while in the pandemic period was 33.6 (p < 0.001). In the pandemic period, the incidence among COVID-19 patients was 38.8 episodes per 100 admissions, while in patients without COVID-19 incidence was 26.6 (p= 0.019). Corticosteroid administration in both periods was not associated with increased candidemia incidence. Conclusions A significant increase of candidemia incidence was observed during the pandemic period in patients with and without COVID-19. This increase cannot be solely attributed to immunosuppression (corticosteroids, tocilizumab) of severe COVID-19 patients, but also to increased workload of medical and nursing staff.

Combination of commercially available molecular assays and culture based methods in diagnosis of tuberculosis and drug resistant tuberculosis

ABSTRACT Early diagnosis of tuberculosis is of major clinical importance. Among 4733 clinical specimens collected from 3363 patients and subjected to Ziehl-Neelsen microscopy, 4109 were inoculated onto Löwenstein-Jensen slants and 3139 in Bactec/9000MB. Polymerase Chain Reaction (PCR) was performed in 3139 specimens, whereas, a genotypic assay was directly applied in 93 Mycobacterium tuberculosis complex PCR-positive for isoniazid and rifampicin resistance detection specimens (GenoType MTBDRplus). Recovered M. tuberculosis isolates (64) as well as, 21 more sent from Regional Hospitals were tested for antimycobacterial resistance with a phenotypic (manual MGIT-SIRE) and a genotypic assay (GenoType MTBDRplus). PCR in the clinical specimens showed excellent specificity (97.4%) and accuracy (96.8%), good sensitivity (70.4%), but low positive predictive value (40.3%). MGIT-SIRE performed to M. tuberculosis did not confer a reliable result in 16 isolates. Of the remaining 69 isolates, 15 were resistant to streptomycin, seven to isoniazid, seven to ethambutol and five to rifampicin. GenoType MTBDRplus correctly detected isoniazid (seven) and rifampicin-resistant M. tuberculosis strains (five), showing an excellent performance overall (100%). Susceptibility results by the molecular assay applied directly to clinical specimens were identical to those obtained from recovered isolates of the corresponding patients. Combining molecular and conventional methods greatly contribute to early diagnosis and accurate susceptibility testing of tuberculosis.