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Dysbiosis plays an important role in the development of bacterial infections in the gastric mucosa, particularly Helicobacter pylori. The international guidelines for the treatment of H. pylori infections suggest standard triple therapy (STT). Nevertheless, because of the increasing resistance rates to clarithromycin, metronidazole has been widely considered in several countries. Unfortunately, the non-justified administration of antibiotics induces dysbiosis in the target organ. We characterized the gastric microbiota of patients diagnosed with follicular gastropathy and pangastropathy attributed to H. pylori infection, before and after the administration of STT with metronidazole. Dominant relative abundances of Cutibacterium were observed in pre-treatment patients, whereas H. pylori was observed at Cutibacterium acnes and H. pylori with gastric infectious diseases was also evaluated using quantitative real-time polymerase chain reaction. The dominance of C. acnes over H. pylori was observed in gastritis, gastropathies, and non-significant histological alterations. None of the microorganisms were detected in the intestinal metaplasia. Post-treatment alterations revealed an increase in the relative abundances of Staphylococcus, Pseudomonas, and Klebsiella. Non-H. pylori gastrointestinal bacteria can be associated with the initiation and development of gastric diseases, such as pathobiont C. acnes.

The poor prognosis of infections associated with multidrug-resistant Pseudomonas aeruginosa can be attributed to several conditions of the patient and virulence factors of the pathogen, such as the type III secretion system (T3SS), which presents the ability to inject four effectors into the host cell: ExoS, ExoT, ExoU and ExoY. The aim of this study was to analyze the distribution of exo genes through multiplex polymerase chain reaction in P. aeruginosa strains isolated from patients at a third-level pediatric hospital and their relationships with clinical variables, e.g., the origin of the sample, susceptibility profile and outcome, through a multinomial logistic regression model. A total of 336 bacterial strains were obtained from cystic fibrosis (CF; n = 55) and bloodstream infection (BSI; n = 281) samples, and eleven presence (+)/absence (−) exo virulotype patterns were identified. The virulotype V3 (exoU−/exoS+/exoT+/exoY+) was observed in 64.28%, followed by V1 (exoU+/exoS−/exoT+/exoY+) with 11.60%. Additionally, V2 (exoU+/exoS−/exoT+/exoY−) was present in 11.60%, and V7 (exoU−/exoS+/exoT+/exoY−) was present in 4.17%. The remaining virulotypes (8.33%) identified were clustered in the other virulotype (OV) group (V4, V5, V6, V8, V9, V10 and V11). The clinical records of 100 patients and their outcomes were reviewed. Fifteen patients died (CF = 4; BSI = 11). V2 and V1 were the virulotypes most related to pandrug resistance (PDR), whereas the V1 relative risk of death was determined to be almost four-fold greater than that of V3, followed by V2 and OV. In summary, the virulotypes V1, V2 and CF are related to death. This study highlights the association of T3SS virulotypes with the susceptibility profile, clinical origin and their potential for predicting a poor prognosis.

Atypical bacterial pathogens present the ability to induce pulmonary damage. At present, there are no available phenotypic diagnosis tests that achieve up to 100% reliability. Therefore, clinicians must utilise molecular techniques for the detection and identification of these pathogens. The main objective of this research was to evaluate the prevalence of atypical bacteria in paediatric patients from different age groups. A total of 609 clinical samples were collected from paediatric patients who presented with an adverse respiratory condition during the period from March 2021 to February 2024. DNA was extracted from the samples, and end-point PCR was performed to detect atypical bacteria. Statistical analyses were performed to evaluate the bacterial prevalence and assess clinical data from newborns and mothers that could be related to RDS. A total of 139 patients exhibited at least one atypical organism (22.82%). Ureaplasma parvum was more prevalent in neonates, while M. pneumoniae and C. pneumoniae were more prevalent in older infants. Atypical bacteria can be present in all seasons of the year, but their prevalence increases during hot weather. Mixed infections due to atypical bacteria may occur. The risk factors related to the development of RDS are prematurity, low weight, and orotracheal intubation.