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Aeromonas trota is sensitive to most antibiotics and the sole species of this genus susceptible to ampicillin. This susceptibility profile could be related to its inability to acquire exogenous DNA. In this study, A. trota isolates were analyzed to establish their capacity to incorporate foreign DNA. Fourteen strains were identified as A. trota by multilocus phylogenetic analysis (MLPA). Minimal inhibitory concentrations of antibiotics (MIC) were assessed, confirming the susceptibility to most antibiotics tested. To explore their capacity to be transformed, A. trota strains were used as recipients in different horizontal transfer assays. Results showed that around fifty percent of A. trota strains were able to incorporate pBAMD1-2 and pBBR1MCS-3 plasmids after conjugal transfer. In all instances, conjugation frequencies were very low. Interestingly, several isoforms of plasmid pBBR1MCS-3 were observed in transconjugants. Strains could not receive pAr-32, a native plasmid from A. salmonicida. A. trota strains were unable to receive DNA by means of electroporation, natural transformation or vesiduction. These results confirm that A. trota species are extremely refractory to horizontal gene transfer, which could be associated to plasmid instability resulting from oligomerization or to the presence of defense systems against exogenous genetic material in their genomes. To explain the poor results of horizontal gene transfer (HGT), selected genomes were sequenced and analyzed, revealing the presence of defense systems, which could prevent the stable incorporation of exogenous DNA in A. trota.

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.

Tuberculosis continues to be a public health problem in the world, and drug resistance has been a major obstacle in its treatment. Quinoxaline 1,4-di-N-oxide has been proposed as a scaffold to design new drugs to combat this disease. To examine the efficacy of this compound, this study evaluates methyl, ethyl, isopropyl, and n-propyl esters of quinoxaline 1,4-di-N-oxide derivatives in vitro against Mycobacterium tuberculosis (pansusceptible and monoresistant strains). Additionally, the inhibitory effect of esters of quinoxaline 1,4-di-N-oxide on M. tuberculosis gyrase supercoiling was examined, and a stability analysis by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS) was also carried out. Results showed that eight compounds (T-007, T-018, T-011, T-069, T-070, T-072, T-085 and T-088) had an activity similar to that of the reference drug isoniazid (minimum inhibitory concentration (MIC) = 0.12 µg/mL) with an effect on nonreplicative cells and drug monoresistant strains. Structural activity relationship analysis showed that the steric effect of an ester group at 7-position is key to enhancing its biological effects. Additionally, T-069 showed a high stability after 24 h in human plasma at 37 °C.

Bacteriophage therapy is a promising strategy used to treat antimicrobial-resistant or persistent bacterial infections. More recently, the clinical utility of bacteriophages has been rediscovered due to the rise of multi-drug resistance and their potential use in clinical practice as an additional treatment option. In this study, local municipal wastewater facilities, hospital wastewater systems, and freshwater reservoirs were evaluated for the presence of lytic bacteriophages. These phages were isolated using conventional phage isolation techniques: water sample collection and processing, pre-enrichment with the host bacteria, the spot test, and the double-layer method. Plaques were selected according to their morphology and lytic activity on the target bacteria. Clinical isolates and reference strains belonging to the ESKAPE group were the targets during phage isolation. A total of 210 lytic plaque morphotypes with activity against ESKAPE strains were isolated from 22 water samples. Each isolate was qualitatively evaluated for its ability to inhibit the growth of its host strain. Thirty-one translucent plaques with apparent lytic activity were selected for purification. Of these, 87.1% were isolated from wastewater samples, and 12.9% were isolated from flowing freshwater. Specifically, the phages isolated from the freshwater samples targeted Staphylococcus aureus strains, and no phage from Enterococcus faecium strains was isolated. In conclusion, wastewater samples are a suitable source for the isolation of exogenous lytic phages; however, freshwater could be considered an alternative source for the isolation of lytic phages.