Aim: This report presents phenotypic and genetic data on the prevalence and characteristics of extended-spectrum β-lactamases (ESBLs) and representative carbapenemases-producing Gram-negative species in Mexico. Material and methods: A total of 52 centers participated, 43 hospital-based laboratories and 9 external laboratories. The distribution of antimicrobial resistance data for Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae complex, Acinetobacter baumannii complex, and Pseudomonas aeruginosa in selected clinical specimens from January 1 to March 31, 2020 was analyzed using the WHONET 5.6 platform. The following clinical isolates recovered from selected specimens were included: carbapenem-resistant Enterobacteriaceae, ESBL or carbapenem-resistant E. coli, and K. pneumoniae, carbapenem-resistant A. baumannii complex, and P. aeruginosa. Strains were genotyped to detect ESBL and/or carbapenemase-encoding genes. Results: Among blood isolates, A. baumannii complex showed more than 68% resistance for all antibiotics tested, and among Enterobacteria, E. cloacae complex showed higher resistance to carbapenems. A. baumannii complex showed a higher resistance pattern for respiratory specimens, with only amikacin having a resistance lower than 70%. Among K. pneumoniae isolates, bla_TEM, bla_SHV, and bla_CTX were detected in 68.79%, 72.3%, and 91.9% of isolates, respectively. Among E. coli isolates, bla_TEM, bla_SHV, and bla_CTX were detected in 20.8%, 4.53%, and 85.7% isolates, respectively. For both species, the most frequent genotype was bla_CTX-M-15. Among Enterobacteriaceae, the most frequently detected carbapenemase-encoding gene was bla_NDM-1 (81.5%), followed by bla_OXA-232 (14.8%) and bla_oxa-181(7.4%), in A. baumannii was bla_OXA-24 (76%) and in P. aeruginosa, was bla_IMP (25.3%), followed by bla_GES and bla_VIM (13.1% each). Conclusion: Our study reports that NDM-1 is the most frequent carbapenemase-encoding gene in Mexico in Enterobacteriaceae with the circulation of the oxacillinase genes 181 and 232. KPC, in contrast to other countries in Latin America and the USA, is a rare occurrence. Additionally, a high circulation of ESBL bla_CTX-M-15 exists in both E. coli and K. pneumoniae.

Background: Infections caused by Stenotrophomonas maltophilia and related species are increasing worldwide. Unfortunately, treatment options are limited, whereas the antimicrobial resistance is increasing. Methods: We included clinical isolates identified as S. maltophilia by VITEK 2 Compact. Ceftazidime/avibactam, meropenem/vaborbactam, imipenem/relebactam, cefiderocol, quinolones, and tetracycline family members were evaluated by broth microdilution method and compared with first-line treatment drugs. Minimum inhibitory concentrations (MICs) were reported for all antibiotics. We sequenced the Whole Genome of cefiderocol resistant strains (CRSs) and annotated their genes associated with cefiderocol resistance (GACR). Presumptive phylogenetic identification employing the 16S marker was performed. Results: One hundred and one clinical strains were evaluated, sulfamethoxazole and trimethoprim, levofloxacin and minocycline showed susceptibilities of 99.01%, 95.04% and 100% respectively. Ceftazidime was the antibiotic with the highest percentage of resistance in all samples (77.22%). Five strains were resistant to cefiderocol exhibiting MIC values ≥ 2 μg/mL (4.95%). The β-lactamase inhibitors meropenem/vaborbactam and imipenem/relebactam, failed to inhibit S. maltophilia, preserving both MIC₅₀ and MIC₉₀ ≥64 μg/mL. Ceftazidime/avibactam restored the activity of ceftazidime decreasing the MIC range. Tigecycline had the lowest MIC range, MIC₅₀ and MIC_90. Phylogeny based on 16S rRNA allowed to identify to cefiderocol resistant strains as putative species clustered into Stenotrophomonas maltophilia complex (Smc). In these strains, we detected GARCs such as Mutiple Drug Resistance (MDR) efflux pumps, L1-type β-lactamases, iron transporters and type-1 fimbriae. Conclusion: Antimicrobial resistance to first-line treatment is low. The in vitro activity of new β-lactamase inhibitors against S. maltophilia is poor, but avibactam may be a potential option. Cefiderocol could be considered as a potential new option for multidrug resistant infections. Tetracyclines had the best in vitro activity of all antibiotics evaluated.

The identification of carbapenemase-producing Enterobacterales and Pseudomonas aeruginosa is important for treating and controlling hospital infections. The recommended methods for their identification require a long waiting time, technical training, and expertise. Lateral flow immunoassays such as NG-Test CARBA 5^® overcome these needs. We analyzed 84 clinical isolates of carbapenem-resistant Enterobacterales and P. aeruginosa from four different hospitals in a two-year period. Antimicrobial resistance patterns were confirmed with the broth dilution method. Evaluation of KPC, VIM, NDM, IMP, and OXA-48-like enzymes was performed and compared to NG-Test CARBA 5 and phenotypic assays. Enterobacterales represented 69% of isolates and P. aeruginosa represented 31%. Carbapenemase-producing strains were 51 (88%) of Enterobacterales and 23 (88.4%) of P. aeruginosa; 20 (34%) and 23 (88%) were Class B ß-lactamases, respectively. The NG-Test CARBA 5^® assay for Enterobacterales showed high sensitivity (98%), specificity (100%), and PPV (100%); however, it did not for P. aeruginosa. The Kappa concordance coefficient was 0.92 for Enterobacterales and 0.52 for P. aeruginosa. NG-Test CARBA 5^® is a fast and easy-to-use assay. In Enterobacterales, we found excellent agreement in our comparison with molecular tests. Despite the low agreement in P. aeruginosa, we suggest that this test could be used as a complementary tool.

Background: Trueperella bernardiae is a Gram‐positive rod that has been described as an opportunistic pathogen in immunocompromised patients. In a significant number of documented cases, infections with Trueperella bernardiae have been associated with polymicrobial infections, which highlight the fact that important bacteria–bacteria relations might be involved in the natural course of these infections, especially in patients with chronic disease courses and a history of multiple antibiotic treatments. Case Presentation: We present a case of a 24‐year‐old woman with a 3‐year history of a chronic pressure ulcer on the right foot associated with varus and cavus deformity. As per relevant medical history, she was positive for multiple wound healing sessions with wound debridement and a large number of antibiotic treatments with minimal improvement. Microbiological cultures were taken from the wound, and a soft tissue infection diagnosis was initially made. Empirical treatment was initiated with levofloxacin. At 48 h, cultures were positive for Providencia stuartii, Pseudomonas aeruginosa, Proteus penneri, Streptococcus agalactiae , and Trueperella bernardiae , and the susceptibility test was performed. Three weeks later, the symptoms progressed to purulent exudate of the wound and foul‐smelling with the positive probe‐to‐bone test. Diagnosis was changed to polymicrobial osteomyelitis, and antibiotic therapy with ciprofloxacin and trimethoprim‐sulfamethoxazole was prescribed for a 4‐week course of treatment, achieving the complete remission of symptoms. Conclusions: Trueperella bernardiae represents an emerging bacterium that can be isolated in various clinical presentations. On osteoarticular infections, the presence of comorbidities, mobility limitations, and a history of multiple antibiotic treatments may be determinant. Their isolation as part of polymicrobial infections highlights relevant interspecies interactions. Research is still lacking in determining standardized methodologies for susceptibility testing and specific clinical breakpoints to guide clinical decisions.

The genus Carnobacterium belongs to lactic acid bacteria, this group are composed by 12 species. These microorganisms are associated with mucosal surface, present in food-related habitats including plant, wine, milk, and meat environments. In humans, evidence of Carnobacterium spp., about the disease spectrum remains unknown. Current work is about a 25-year-old male, was admitted to the emergency room for transmetacarpal traumatic amputation of his left hand caused by a meat grinder. In deep soft tissue samples obtained from surgery, Carnobacterium divergens was isolated. He was treated with piperacillin-tazobactam and was switched to amoxicillin-clavulanate for five more days with clinical success. Written informed consent was obtained from the participating patient for publication of this case report and any accompanying images. Therefore, the pathogenic role of Carnobacterium spp., remains unknown and classically is not considered pathogenic to humans. However, in previous cases where was associated with infection, the described outcomes were good. The misidentification showed that conventional identification methods are not accurate.