Objetivo: Describir y caracterizar la microbiología de las osteomielitis de pie diabético en pacientes hospitalizados en el Hospital San Juan de Dios en el año 2018. Métodos: Se consultó la base de datos local de pacientes de la Unidad de Pie Diabético para obtener los datos demográficos de los pacientes hospitalizados con diagnóstico de osteomielitis además del sistema de información de la división de Microbiología del Laboratorio Clínico con el fin de obtener los datos de especies bacterianas y sus perfiles de susceptibilidad a los antimicrobianos aisladas de las respectivas muestras de hueso. Con estos datos se construyó una base de datos para el proyecto y el análisis estadístico descriptivo se realizó en hojas de cálculo de Excel. Resultados: Enterococcus faecalis fue el agente más frecuentemente aislado (21%), seguido de Staphylococcus aureus (14%), de los cuales 70% presentó fenotipo de meticilino resistencia y Escherichia coli como tercer lugar (11%). Otros bacilos Gram negativos ocuparon un cuarto lugar, con Enterobacter cloacae (8%) y Klebsiella pneumoniae (8%) como las principales especies aisladas; cabe destacar que se evidenció la presencia de 24% de cepas portadoras de β-lactamasas de espectro extendido, con K. pneumoniae como la principal especie portadora de este fenotipo de resistencia. Conclusiones: Se reportó por primera vez a E. faecalis como la bacteria más aislada en OPD, lo cual permite concluir que la microbiología de estos cuadros en Costa Rica difiere a lo reportado en la literatura internacional y es necesario actualizar a la comunidad médica costarricense. Además, es importante destacar que a pesar de que el porcentaje obtenido de bacilos Gram negativos portadores de BLEE es inferior a lo reportado en la literatura, el 100% de las cepas de K. pneumoniae fueron portadoras de este fenotipo de resistencia, por lo tanto, es posible considerar a nivel local que el hallazgo preliminar de esta especie debería modificar el espectro terapéutico a utilizar en espera de reportes de PSA.

All carbapenem-resistant Gram-negative bacterial isolates obtained in the Costa Rican National Network of Bacteriology Laboratories are routinely referred to the National Reference Center for Bacteriology for national-laboratory for surveillance and characterization of their carbapenem-related-mechanism of resistance. As a result of this healthcare-associated infection surveillance, two bacterial isolates with unknown mechanisms for carbapenem resistance were investigated. The isolates were subjected to taxonomic identification, antimicrobial susceptibility testing, whole-genome characterization, using Illumina and Oxford Nanopore technologies, and bioinformatic analyses. The isolates were identified as Enterobacter roggenkampii and Enterobacter sichuanensis. While the isolates presented different antimicrobial resistance profiles, both were resistant to carbapenems, positive for the modified carbapenem inactivation method (mCIM), and showed inhibition of carbapenem resistance with boronic acid. The full characterization of the isolates' genomes, revealed the presence of the rare chromosomal blaIMI-4 gene inserted within 25-kb integrative mobile elements, closely related to EcloIMEX-2. The limited global distribution of the blaIMI-4 variant, along with its identification in two distinct bacterial species in Costa Rica within integrative mobile elements, underscores the critical need for regular antibiotic resistance surveillance using next-generation sequencing technologies. This study demonstrates that this practice allows timely detection of novel or rare mechanisms of antibiotic resistance.

Carbapenem resistance is considered one of the greatest current threats to public health, particularly in the management of infections in clinical settings. Carbapenem resistance in bacteria is mainly due to mechanisms such as the production of carbapenemases (such as the imipenemase IMP, or other enzymes like VIM, NDM, and KPC), that can be detected by several laboratory tests, including immunochromatography and automated real-time PCR (qPCR). Methods: As part of local studies to monitor carbapenem-resistant bacteria in Costa Rica, two cases were initially identified with inconsistent IMP detection results. A possible gene drop-out in the automated qPCR test was suggested based on the negative result, contrasting with the positive result by immunochromatography and whole-genome sequencing. We hypothesized that molecular testing could be optimized through the development of tailored assays to improve the detection of IMP genes. Thus, using IMP gene sequences from the local isolates and regional sequences in databases, primers were redesigned to extend the detection of IMP alleles of regional relevance. Results: The tailored qPCR was applied to a local collection of 119 carbapenem-resistant isolates. The genomes of all 14 positive cases were sequenced, verifying the results of the custom qPCR, despite the negative results of the automated testing. Conclusions: Guided by whole-genome sequencing, it was possible to extend the molecular detection of IMP alleles circulating in Latin America using a tailored qPCR to overcome IMP gene drop-out and false-negative results in an automated qPCR.

Background: Carbapenem-resistant Acinetobacter baumannii (CRAB) is a critical pathogen associated with severe hospital infections and high antimicrobial resistance. Despite the global significance of A. baumannii, there are limited data from Costa Rica regarding the resistance rate and genomic characteristics of CRAB. Methods: This study aimed to provide initial and exploratory epidemiological data on infections caused by A. baumannii and CRAB isolated in Costa Rica and to gain insights on the genome of selected strains, focusing on their resistance determinants and phylogenetic relationships. Results: Based on data from five main hospitals in Costa Rica, resistance rate to carbapenems was estimated at 9.8% to imipenem and 6.1% to meropenem. From 190 carbapenem-resistant clinical isolates available in a local collection, seven A. baumannii strains were identified, all showing resistance to carbapenems and carrying the bla_NDM-1 gene. Whole-genome sequencing of two strains yielded two distinct MLST profiles (Pasteur scheme: ST-150 for strain IPAT15 and ST-250 for IPAT72), as well as variations in the number and identity of plasmids, genomic islands, and other elements of the mobilome. Both isolates carried ten antimicrobial resistance genes, which are predicted to be harbored in plasmids for IPAT15, unlike the chromosomal determinants in IPAT72. A pangenome analysis of 878 genomes from a public database identified over 51,000 genes, with only 1338 (2.6%) forming the core genome. Phylogenetic analysis and assignation of international clones (ICs) showed predominance of IC2. Isolates from Costa Rica clustered near IC9 and shared some resistance determinants, but they were not directly assigned to an IC. Conclusions: Overall, this study provides exploratory insights regarding the occurrence of CRAB in Costa Rica using epidemiological and genomic data, with profiles that are comparable to other regions in Latin America and diverse genomic resistance determinants. While this study does not show the whole landscape of CRAB in Costa Rica, these data constitute an initial approach for improving clinical management and public health responses to CRAB infections, to ultimately improve outcomes for patients affected by this pathogen.

Resumen Las infecciones de pie diabético corresponden a una de las principales complicaciones infecciosas en pacientes con diabetes mellitus, debido a los diversos factores de riesgo a los que se enfrentan estas personas. Si bien el diagnóstico de la infección del pie diabético debe realizarse de forma multidisciplinaria, el diagnóstico microbiológico del agente etiológico de la infección a partir de una muestra clínica es vital, con el fin de iniciar una adecuada terapia antimicrobiana. Dentro de la microbiología de estas infecciones se encuentran diversos agentes bacterianos; las principales bacterias aisladas de cuadros agudos son Staphylococcus aureus y diversas especies del género Streptococcus sp. Sin embargo, en cuadros crónicos pueden presentarse infecciones polimicrobianas en donde se pueden aislar enterobacterias como Escherichia coli, especies de Proteus sp. y bacilos gramnegativos no fermentadores como Pseudomonas aeruginosa. En cuanto al tratamiento empírico de estos cuadros, debe ser dirigido tomando como base la microbiología local de cada centro, ya que de esta forma se optimiza la terapia antimicrobiana; además, cuando se cuente con el dato del antibiograma del aislamiento bacteriano obtenido, se debe realizar el escalamiento o descalamiento de la tera- pia, para disminuir la presión selectiva que conlleve la aparición de cepas multirresistentes a los antimicrobianos, particularmente en el caso de infecciones crónicas.