Background: The increase in antimicrobial resistance includes emerging mechanisms such as 16S ribosomal RNA methylases, which confer high-level resistance to aminoglycosides. In this regard, the most predominant genes observed worldwide are rmtB and armA, but their presence in Uruguay is unknown. Objectives: We describe the genomic characterization of isolates carrying rmtB and rmtC, together with bla_NDM-5 and bla_NDM-1, respectively, and rmtD in our country. Methology: Five isolates from patients admitted to three hospitals were studied. Identification and antibiotic susceptibility testing were performed using the Vitek2 System. Whole Genome Sequencing was conducted, and hybrid assembly was performed with Unicycler. In silico analysis using the Center for Genomic Epidemiology’s tools was undertaken to predict antibiotic resistance determinants, plasmid incompatibility groups, and sequence types. Results: We report three K. pneumoniae ST307 isolates with an IncR plasmid carrying bla_NDM-5/bla_CTX-M-15/bla_TEM-1B/rmtB/dfrA14/dfrA12/sul1/qacEΔ1/ermB/mphA, one K. pneumoniae ST258 harboring an IncC plasmid containing rmtC/bla_NDM-1/bla_CMY-6/aac(6′)-Ib/sul1, and one E. cloacae ST88 isolate with an IncFIB/II plasmid hosting rmtD, within a novel Tn21-like transposon named Tn7825, alongside bla_OXA-101/sul1/tet(G)/floR, and a new variant of bla_TEM assigned as bla_TEM-258. One of the strains, named UH_B2, also carried an IncM1 plasmid encoding qnrE1/bla_TEM-1/bla_CTX-M-8 associated with ISEcp1. Conclusions: This is the first description of plasmids harboring 16S rRNA methyltransferases in Uruguay. The association and dissemination of diverse antibiotic-resistant genes underpin the health threat they represent, highlighting the lack of available antibiotics effective against multidrug-resistant microorganisms.

Vancomycin is the cornerstone in treating methicillin-resistant Staphylococcus aureus (MRSA) infections. However, therapeutic failures can occur when MRSA strains with decreased susceptibility to glycopeptides (DSG) are involved. The aim of this study was to detect and characterize DSG in MRSA recovered from children with invasive diseases at a reference pediatric hospital between 2009 and 2019. Fifty-two MRSA strains were screened using agar plates with vancomycin 3 and 4 mg/L (BHI-3 and BHI-4); the VITEK2 system; and standard and macro E-tests. Suspicious hVISA were studied by population analysis profiling–area under the curve (PAP-AUC), and wall thickness was analyzed by transmission electron microscopy. Neither VRSA nor VISA were detected in this set. As only three strains met the hVISA criteria, the PAP-AUC study included 12 additional MRSA strains that grew one colony on BHI-4 plates or showed minimum inhibitory concentrations of vancomycin and/or teicoplanin ≥ 1.5 mg/L. One strain was confirmed as hVISA by PAP-AUC. The wall thickness was greater than the vancomycin-susceptible control strain; it belonged to ST30 and carried SCCmec IV. As expected, a low frequency of hVISA was found (1.9%). The only hVISA confirmed by PAP-AUC was not detected by the screening methods, highlighting the challenge that its detection represents for microbiology laboratories.

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Introducción: la osteomielitis maxilar crónica (OMC) en la adolescencia suele asociarse a complicaciones de una infección odontogénica. Su diagnóstico suele ser clínico, imagenológico y microbiológico, requiriendo un abordaje terapéutico individualizado. El objetivo de esta comunicación es describir el abordaje de un adolescente que presentó OMC secundaria a una celulitis de cara a punto de partida odontogénico.Caso clínico: 11 años, obeso, mala higiene bucal. Celulitis de cara de causa odontogénica cuatro meses atrás, tratamiento incompleto. Consulta por edema de hemicara derecha, calor, rubor y odontalgia de tres días de evolución. No fiebre. Se realiza drenaje de la pieza dental e indica antibioticoterapia. A las 48 horas, reconsulta por aumento del edema. Examen físico: buen aspecto general, tumoración en hemimandíbula derecha que se extiende a región suprahioidea, límites mal definidos, 6 x 4 cm, ovoidea, blanda, con área central fluctuante, halo eritematoso y edema peritumoral. Dolor a la palpación del reborde mandibular derecho. Cavidad oral: múltiples focos sépticos, a nivel del primer premolar derecho drenaje de pus espontáneo. Tratamiento: drenaje y extracción de pieza dentaria Nº 46; antibioticoterapia con clindamicina, gentamicina y cefuroxime. Cultivo del drenaje desarrolla Streptococcus constellatus spp constellatus. Se continúa con penicilina G por 10 días, y luego amoxicilina completando 21 días de tratamiento. Buena evolución.Discusión: la OMC suele ser una complicación de una infección odontogénica no tratada o abordada inadecuadamente, como ocurrió en este caso, identificándose a Streptococcus constellatus como agente causal. El tratamiento suele ser médico-quirúrgico guiado por un equipo interdisciplinario. Es importante promover la higiene bucal y mantener los controles odontológicos para prevenir esta patología.