Discover the three studies we selected in April’s Microbiology Time.

• The first study we selected explored the potential of using tongue swabbing as a substitute for sputum in tuberculosis (TB) testing. Previous research indicated that the Cepheid Xpert Ultra platform performs well compared to reference standards on buffer-preserved sputum samples. Here, the researchers assessed the same platform on 245 self-collected and dry-stored tongue swabs and compared the results with the Molbio Truenat MTB Ultima (MTB Ultima) assay. Xpert Ultra showed 75.5% sensitivity and 100% specificity compared to sputum testing, while MTB Ultima demonstrated 71.6% sensitivity and 96.9% specificity, improving to 79.1% sensitivity after re-testing frozen samples initially yielding false-negative or invalid results. These findings highlight the feasibility of using tongue swabs as easy-to-collect samples for TB testing.
• For the second study, we move to Indonesia, where Dr. Wulandri and colleagues investigated the pathogens causing acute diarrhea in children, comparing HIV-infected and non-HIV-infected cases at an Indonesian tertiary hospital. Conducted from March 2019 to April 2020, the cross-sectional study utilized multiplex RT-PCR, showing that almost 60% of the samples were positive, with more positive results in HIV-infected children than in non-HIV-infected children (70% vs. 54.7%). Overall, 72 enteropathogens were detected, with non-HIV cases primarily showing bacterial infections with enteroaggregative Escherichia coli as predominant, followed by viral infections. In contrast, HIV-infected children exhibited a mix of viruses, bacteria, and parasites with Cryptosporidium spp. solely detected in this group. Notably, non-HIV children predominantly presented with invasive bacterial pathogens, while HIV-infected children showed more viral and parasitic infections, often attributed to opportunistic pathogens.
• The last study investigated the relationship between gut microbiome composition and clinical outcomes in COVID-19 patients. Stool samples and patient records were collected from 24 hospitalized individuals with confirmed SARS-CoV-2 infection. Fungal and bacterial gut microbiome was characterized by amplicon sequencing on the Illumina MiSeq. The results revealed that female COVID-19 patients had lower gut bacterial microbiota richness compared to males, possibly influenced by differences in hospital admission timing. Both sexes exhibited associations with opportunistic bacterial pathogens like Enterococcus and Streptococcus. The Candida genus dominated the gut mycobiota of COVID-19 patients, with adults showing higher fungal diversity than the elderly. Notably, Saccharomycetales unassigned fungal genera correlated with bacterial short-chain fatty acid producers and negatively with proinflammatory bacteria like Bilophila. Patients harboring this fungal taxon were not admitted to high-intensity units. The study underscores the association between COVID-19 and opportunistic bacterial pathogens, highlights Candida dominance in the gut, and suggests a potential protective role for specific fungal taxa, warranting further investigation into their role in gastrointestinal health and disease outcomes.

Read the full studies: