Search

The occurrence of multidrug-resistant Serratia marcescens strains represents a serious public health threat. The purpose here is to report three cases of carbapenem-resistant S. marcescens infections with unfavorable clinical outcomes and provide a molecular description of the antibiotic resistance determinants at a genomic level. We performed bacterial identification by VITEK 2 and MALDI-TOF. The minimal inhibitory concentrations of antimicrobials were determined according to the Clinical and Laboratory Standards Institute guidelines, except for tigecycline, for which they were determined using Etest strips. Preliminary screening for the presence of carbapenemases was performed by ertapenem hydrolysis using MALDI-TOF MS. Whole-genome sequencing was provided to identify genes responsible for virulence and antimicrobial resistance. Here we report three challenging cases of S. marcescens that were resistant to the most commonly used antibiotics. Otherwise, we performed a genome description, which includes several genes involved in the resistance and virulence. These cases illustrate serious infection due to multidrug-resistant organisms and the complexity of treatment. Our results highlight the need to evaluate isolates regularly during long-term hospital stay to achieve optimal quality of clinical care and thus improve patient outcomes., (© 2021. Sociedade Brasileira de Microbiologia.)

Campylobacter jejuni is the most common bacterial cause of foodborne diarrheal disease worldwide and is among the antimicrobial resistant "priority pathogens" that pose greatest threat to public health. The genomes of two C. jejuni isolated from poultry meat sold on the retail market in Southern Brazil phenotypically characterized as multidrug-resistant (CJ100) and susceptible (CJ104) were sequenced and analyzed by bioinformatic tools. The isolates CJ100 and CJ104 showed distinct multilocus sequence types (MLST). Comparative genomic analysis revealed a large number of single nucleotide polymorphisms, rearrangements, and inversions in both genomes, in addition to virulence factors, genomic islands, prophage sequences, and insertion sequences. A circular 103-kilobase megaplasmid carrying virulence factors was identified in the genome of CJ100, in addition to resistance mechanisms to aminoglycosides, beta-lactams, macrolides, quinolones, and tetracyclines. The molecular characterization of distinct phenotypes of foodborne C. jejuni and the discovery of a novel virulence megaplasmid provide useful data for pan-genome and large-scale studies to monitor the virulent C. jejuni in poultry meat is warranted.