Introduction: Carbapenem-resistant Pseudomonas aeruginosa (CRPA) has been isolated with increasing frequency in Brazilian hospitals. Since June 2003, its detection in a teaching hospital in the city of Florianópolis, Brazil, has increased. This study aimed to investigate the minimal inhibitory concentration (MIC), presence of Metallo-β-lactamase (MβL) and a possible clonal relationship among the isolates. Methods: The study included 29 CRPA and seven isolates with reduced susceptibility. The MIC was determined by agar-dilution. Detection of MβL was performed by Double Disk Sinergism (DDS) and Combined Disk (CD). The MβL gene was verified by PCR and nucleotide sequence analysis. Epidemiological typing was performed by pulsed-field gel electrophoresis. Results: Among the 29 carbapenem-resistant isolates, polymyxin B presented 100% susceptibility and piperacillin/tazobactam 96.7%. Seventeen (62%) strains were verified as clonal (A clone) and among these, six isolates indicated phenotypically positive tests for MβL and harbored the bla SPM-1 gene. The first CRPA isolates were unrelated to clone A, harbored bla IMP-16 and were phenotypically positive only by CD. Conclusions: The spread of a high-level of resistance clone suggests cross transmission as an important dissemination mechanism and has contributed to the increased rate of resistance to carbapenems. This study emphasizes the need for continuous surveillance and improved strategies for infection control in this institution.

This study aimed to assess the ultrapure cannabidiol (CBD) antibacterial activity and to investigate the antibacterial activity of the combination CBD + polymyxin B (PB) against Gram-negative (GN) bacteria, including PB-resistant Gram-negative bacilli (GNB). We used the standard broth microdilution method, checkerboard assay, and time-kill assay. CBD exhibited antibacterial activity against Gram-positive bacteria, lipooligosaccharide (LOS)-expressing GN diplococcus (GND) (Neisseria gonorrhoeae, Neisseria meningitidis, Moraxella catarrhalis), and Mycobacterium tuberculosis, but not against GNB. For most of the GNB studied, our results showed that low concentrations of PB (≤ 2 µg/mL) allow CBD (≤ 4 µg/mL) to exert antibacterial activity against GNB (e.g., Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii), including PB-resistant GNB. CBD + PB also showed additive and/or synergistic effect against LOS-expressing GND. Time-kill assays results showed that the combination CBD + PB leads to a greater reduction in the number of colony forming units per milliliter compared to CBD and PB alone, at the same concentration used in combination, and the combination CBD + PB was synergistic for all four PB-resistant K. pneumoniae isolates evaluated. Our results show that CBD has translational potential and should be further explored as a repurposed antibacterial agent in clinical trials. The antibacterial efficacy of the combination CBD + PB against multidrug-resistant and extensively drug-resistant GNB, especially PB-resistant K. pneumoniae, is particularly promising.

There is an increasing number of reports worldwide about multidrug resistance (MDR) with potential of ExPEC in commensal E. coli. The present study evaluated the potential ExPEC in selected 44 MDR E.coli isolates, collected from livestock. ExPEC isolates were characterized by analysis of five main groups of virulence genes (papA and/or papC, sfa and/or foc, afa and/or dra, kpsMT II and iutA). We also determined the increased virulence potential analyzing other 29 virulence genes, the epidemiology of these isolates. Additionally, fifteen ExPEC isolates were selected to evaluate the adhesion and invasion capacity in vitro using Caco-2 cells. Based on the analysis of the five main virulence genes, 72.7% (32/44) strains were classified as ExPEC. The presence of each gene was iutA 88.6%, KpsMT II 70.4%, papC 25%, sfa/focDE 4.5%; afa/draBC genes were not found. All E. coli isolates were classified into: phylogenetic groups A (34%), B1 (10%), B2 (20%), and D (36%). MLST revealed 7 different STs among isolates, including a new ST identified (ST5687). The in vitro assay in Caco-2 cells showed that all isolates were capable to adhere or invade the epithelial cells, although this occurred at variable levels. The ExPEC isolate LO122 reached similar levels of invasion to the positive control strain Salmonella Typhimurium LT2. These results showed that the apparently commensal microbiota of poultry harbors MDR ExPEC isolates with high adhesion and invasion potential.

RESUMO: A tipagem molecular do genoma bacteriano, na maioria das vezes, envolve a análise de fragmentos de restrição do DNA cromossômico. Desde que a ribotipagem foi descrita, em 1986, tem sido amplamente utilizada para analisar relações taxonômicas e/ou epidemiológicas entre os diferentes grupos de organismos. A ribotipagem usa o padrão de restrição do opéron de RNA ribossômico (rrn) como ferramenta epidemiológica e tem fornecido ótimos resultados para a detecção de polimorfismo do comprimento dos fragmentos de restrição (RFLPs). O número de opérons rrn da bactéria está diretamente relacionado ao potencial discriminatório da técnica, fornecendo um maior ou menor número de bandas. UNITERMOS: Epidemiologia Molecular. Técnicas para Tipagem de Bactérias. Infecções Bacterianas.

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High frequency transfer and elimination of drug resistance may indicate an extrachromosomal inheritance of genetic determinants. This study shows the cure and transfer of a small plasmid and tetracycline resistance in Staphylococcus aureus 1030 (55)Tet R strains. Several methods are available for plasmid elimination. We used ethidium bromide, an agent that binds to DNA, and thus inhibits DNA polymerase. This caused a high frequency of loss of the small plasmid and resistance to tetracycline. Transfer of tetracycline resistance was done in a mixed culture at a frequency of 10-6 • This type of study is very important to physicians and epidemiology investigators and provides better knowledge on antibiotic-resistance mechanisms that may occur in vivo in a hospital environment.

Objective and design Our research aimed to investigate the role of CD14 in pulmonary infection by Achromobacter xylosoxidans in an experimental murine model. Methods C57Bl/6 or CD14-deficient mice were infected intratracheally with non-lethal inoculum of A. xylosoxidans . At times 1, 3 and 7 days after infection, lungs, bronchoalveolar lavage and blood were collected. CD14 gene expression was determined by RT-PCR. The bacterial load in the lungs was assessed by counting colony forming units (CFU). Cytokines, chemokines, lipocalin-2 and sCD14 were quantified by the ELISA method. Inflammatory infiltrate was observed on histological sections stained with HE, and leukocyte subtypes were assessed by flow cytometry. In another set of experiments, C57Bl/6 or CD14-deficient mice were inoculated with lethal inoculum and the survival rate determined. Results CD14-deficient mice are protected from A. xylosoxidans -induced death, which is unrelated to bacterial load. The lungs of CD14-deficient mice presented a smaller area of tissue damage, less neutrophil and macrophage infiltration, less pulmonary edema, and a lower concentration of IL-6, TNF-α, CXCL1, CCL2 and CCL3 when compared with lungs of C57Bl/6 mice. We also observed that A. xylosoxidans infection increases the number of leukocytes expressing mCD14 and the levels of sCD14 in BALF and serum of C57Bl/6-infected mice. Conclusions In summary, our data show that in A. xylosoxidans infection, the activation of CD14 induces intense pulmonary inflammatory response resulting in mice death. Supplementary Information The online version contains supplementary material available at 10.1007/s00011-022-01641-8.

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