Bacterial resistance is a growing challenge in the Amazon, driven by environmental and social factors and inappropriate antimicrobial use. Between 2022 and 2023, 61.9% of Klebsiella pneumoniae strains isolated in public hospitals in Manaus were multidrug-resistant and 23.8% extensively resistant, including clones from group CG258. In this context, the study investigated the influence of Amazonian seasonality on the occurrence, distribution, and resistance of these microorganisms in public healthcare units in the city of Manaus. Retrospective cohort study based on blood cultures processed between August 2024 and April 2025 by public hospitals in Amazonas. Data extracted from the BitLab platform refer to adult and pediatric patients. Microbiological profiles, resistance markers, and seasonal variations were analyzed. Analysis of the microbiological profile revealed predominance of Gram-positive microorganisms in both age groups. A total of 1,144 positive blood cultures with a resistance profile were evaluated. The most prevalent microorganism was Staphylococcus epidermidis, with 74 isolates in adults and 219 in children. Other relevant Gram-positives included S. haemolyticus (45 adults; 59 children), S. aureus (48 adults; 50 children), and S. hominis (24 adults; 36 children). Among Gram-negatives, Klebsiella pneumoniae (72 adults; 96 children), Acinetobacter baumannii (37 adults), and Burkholderia cepacia (41 children) stood out, all with high expression of markers such as ESBL, BLACT, mecA, and carbapenemases. In addition, it was observed that during rainy months, the increase in hospitalizations due to arboviruses, respiratory infections, and leptospirosis coincided with greater occurrence of opportunistic microorganisms and fungi, partly due to humidity, flooding, and indiscriminate antimicrobial use. During the dry season, a more restricted microbiological pattern was noted, linked to consolidated healthcare-associated infections. The findings confirm the impact of seasonality on bacterial resistance in Manaus. The predominance of microorganisms such as S. epidermidis highlights the importance of pre-analytical care. This is the first study to address this epidemiological profile of microbiological resistance in the city, evidencing weaknesses in sample collection and the need for team qualification and control strategies.
Tezza et al. (Sun,) studied this question.