Due to their mass production and intense consumption in human medicine, veterinary, and aquaculture, antibiotics have been widely detected in different ecosystems, leading to a growing worldwide concern. These and their byproducts are being continuously discarded in natural ecosystems via excretion of human and animal urine and feces, also domestic and hospital effluents. Residues of these drugs can persist in natural environments through bioaccumulation due to their difficult biodegradation. Also, they have a gradual deposition in sediments, aquatic surfaces, and groundwater. Studies have shown the presence of these drugs in aquatic environments, which can trigger severe changes in the composition and structure of the bacterial community, such as the ability to develop and propagate genes resistant to these pollutants. In this context, this review aims to address the effects of the antibiotics on microorganisms present in impacted aquatic environments.

Staphylococcus aureus is a frequent cause of infections worldwide. Methicillin-resistant S. aureus (MRSA) is one of the main causes of Gram-positive infections, and methicillin-susceptible strains (MSSA) primarily colonize and infect community hosts. Multiple virulence factors are involved, with toxins playing a significant role in several diseases. In this study, we assess the prevalence of toxin genes in 89 S. aureus clinical isolates (31 MRSA and 58 MSSA). We evaluated the discriminatory power of the association of internal transcribed spacer-PCR (ITS-PCR) and 3’- end coa gene ( coa-PCR) when compared with other more commonly used and costly techniques. The isolates showed a high level of genetic diversity, and toxins were found in all the isolates. While most toxin classes displayed no statistically significant correlations and were equally distributed in isolates regardless of their resistance status, classic enterotoxins ( sea-see) showed a positive correlation with MSSA isolates. The combination of coa-PCR with ITS-PCR showed a discriminatory index of 0.84, discriminating 22 genotypes that agree with previously determined data by PFGE and MLST. This association between the two PCR-based methods suggests that they can be useful for an initial molecular epidemiological investigation of S. aureus in hospitals, providing significant information while requiring fewer resources.

Artisanal coalho cheese is a dairy derivative traditionally produced in the Northeast region of Brazil, often using raw milk, which helps preserve its microbiota, especially lactic acid bacteria (LAB). This study aimed to isolate and identify LAB present in artisanal coalho cheeses produced in the Agreste region of Pernambuco, Brazil, and to evaluate the phenotypic and genotypic profiles of antibiotic resistance of these microorganisms. Samples of artisanal coalho cheese were collected from eight cities in the Agreste region. LAB strains were isolated and subjected to Gram staining and catalase assays. Isolates were genotypically identified using the 16 S rRNA gene sequencing technique. Out of 111 LAB isolates, 32 were selected for antibiotic susceptibility studies using 12 different antimicrobials. In addition, seven antimicrobial resistance genes were investigated. The isolates were identified as belonging to the genera Enterococcus , Lactococcus , Streptococcus , Lacticaseibacillus and Lactiplantibacillus . The highest resistance rates were observed for cefoxitin (75.0%) and gentamicin (71.87%). Some strains, such as QCPE34, QCPE48, QCPE63, QCPE112, QCPE123, and QCPE143 were resistant to only one antibiotic, while strain QCPE40 was resistant to eight antibiotics. Overall, high levels of antibiotic resistance were observed, with 68.75% of strains classified as multidrug-resistant (MDR). Tetracycline and/or erythromycin resistance genes were detected in 16 of the 32 strains tested. This raises an alert regarding food safety for consumers, representing a potential risk to the environment and public health.

Abarema cochliacarpos popularly known as "Barbatimão" is a tree with medicinal properties, easily found in the Atlantic Forest and the Brazilian Cerrado, being little studied by scientists. This study aimed to evaluate the antimicrobial activity of 4 fractions (ethanol, hexane, ethyl acetate and methanol/water) of A. cochliacarpos against three mixed bacterial cultures of the oral cavity, and their cytotoxicity on human red blood cells. A narrative review was carried out using A. cochliacarpos and Barbatimão as descriptors to identify the main compounds with biological activities in the plant. Through a narrative review, it was seen that this species has saponin alkaloids, terpenes, flavonoids, steroids and tannins being responsible for the biological activities. Antimicrobial activity was determined by measuring the halo of inhibition of microbial growth, using ethanolic fraction at concentrations of 100, 50, and 25 mg/ml, and other fractions at concentrations of 25 and 10 mg/ml. The ethanol extract showed the best performance with halos of 10.60 mm at its lowest concentration, while ethyl acetate showed the worst performance, not forming halos in the 3 concentrations tested. The minimum inhibitory concentration (MIC) was 22 mg/ml, this concentration was able to inhibit microbial growth in all samples against the 3 inoculums. In this study, Barbatimão extracts did not present toxicity in hemolytic activity. In view of this research, it was possible to observe that Barbatimão showed antimicrobial activity and no toxicity, arousing the interest of new in vivo studies.

Staphylococcus aureus is a major pathogen among bacterial infections, also having the ability to produce biofilm, thus becoming tolerant and resistant to antibiotics and immune responses. Essential oil extracted from plants has shown broad-spectrum antibacterial and antibiofilm activities against bacteria. In this study it was evaluated whether rosemary, clove and cinnamon essential oil exert antibacterial and antibiofilm activities against S. aureus in vitro. The essential oils were purchased and their chemical composition was identified by gas chromatography and mass spectrometry (GC-MS). Antibiofilm and antibacterial effects were assessed by the 96-well microtiter plate adhesion assay. The highest antimicrobial and antibiofilm activity were observed with 3% and 6% cinnamon essential oil while the essential oil of clove and rosemary did not show satisfactory results. These results support new antimicrobial therapies against S. aureus infections and biofilm formation, using cinnamon essential oil, thus contributing to both human and veterinary medicines.

Ectotherm vulnerability to climate warming is often assessed using upper thermal limits (CTmax values), yet the latter’s underlying physiological mechanisms remain poorly understood. Heat shock proteins (HSPs), particularly Hsp70, are frequently assumed to play a central role in thermal tolerance because they protect cellular proteins against heat-induced damage. However, little direct evidence supports a temporal association between Hsp70 expression and CTmax values within species. We explored seasonal and diel differences in relative Hsp70 expression and CTmax values in a natural population of the thermophilic ant Dorymyrmex thoracicus. We also tested whether relative Hsp70 expression was positively related to CTmax values. Workers were sampled during contrasting seasons (summer vs. winter) and at contrasting times of day (midday vs. evening). Soil temperatures were significantly higher in the summer and at midday. Relative Hsp70 expression differed significantly between seasons and was approximately 2.3 times higher in the summer than the winter. In contrast, CTmax values displayed the opposite pattern: they were higher in the winter than the summer. Furthermore, colonies with higher relative Hsp70 expression had lower CTmax values, which challenges the commonly held idea that greater Hsp70 expression reflects enhanced heat tolerance. Instead, higher levels of Hsp70 expression may indicate that an organism is experiencing increased physiological stress under warmer conditions, and CTmax values may be shaped by other mechanisms, such as hydration status and acclimation history. More broadly, our study highlights the need to distinguish between biomarkers of cellular stress and the physiological processes that ultimately determine heat tolerance.