[Colistin resistance in carbapenem-resistant Klebsiella pneumoniae isolates from a pediatric hospital from Corrientes, Argentina]. / Resistencia a colistina en aislados de Klebsiella pneumoniae resistente a carbapenémicos en un hospital pediátrico de Corrientes.

BACKGROUND: There is an increase of carbapenem-resistant Klebsiella pneumoniae (CRKP) infections in the pediatric population and epidemiological data are limited. AIM: To calculate the frequency of CRKP in pediatric patients, to determine the in vitro activity of colistin and to detect the presence of mcr-1 gene in said isolates. METHODS: 220 isolates of K. pneumoniae were studied in a pediatric hospital between January 2018 and December 2019. Antimicrobial susceptibility was determined by microdilution in broth according to guidelines of CLSI and EUCAST. The genes blaKPC, blaNDM, blaIMP, blaVIM, blaOXA-48 and mcr-1 were detected by polymerase chain reaction (PCR). RESULTS: 9.5% (n: 21) of the isolates were characterized as CRKP, where was observed a resistance to colistin of 47.6% (10/21) with values of MIC50 of 2 µg/mL and MIC90 of ≥ 4 µg/mL. In 100% of CRKP strains the blaKPC gene was detected and the mcr-1 gene was not found. The resistance profile to other antimicrobials was as follow: gentamicin 100% (n: 21), trimethoprim/sulfamethoxazole 100% (n: 21), ciprofloxacin 100% (n: 21), amikacin 19% (n: 4). All of the isolates were sensitive to ceftazidime/avibactam and tigecycline. CONCLUSION: This study demonstrates a significant value of resistance to colistin in pediatric patients compared to other last line antimicrobial such as ceftazidime/avibactam and tigecycline.

Resistencia a colistina en aislados de Klebsiella pneumoniae resistente a carbapenémicos en un hospital pediátrico de Corrientes / Colistin resistance in carbapenem-resistant Klebsiella pneumoniae isolates from a pediatric hospital from Corrientes, Argentina

INTRODUCCIÓN: Existe un incremento de las infecciones por Klebsiella pneumoniae resistente a carbapenémicos (KPRC) en la población pediátrica y los datos epidemiológicos son limitados. OBJETIVOS: Conocer la frecuencia de KPRC en pacientes pediátricos, determinar la actividad in vitro de colistina y detectar el gen mcr-1 en dichos aislados. MATERIALES Y MÉTODOS: Se estudiaron 220 aislados de K. pneumoniae en un hospital pediátrico durante los años 2018 y 2019. La susceptibilidad antimicrobiana se determinó por microdilución en caldo según CLSI y EUCAST. Los genes blaKPC, blaNDM, blaIMP, blaVIM, blaOXA-48 y mcr-1 se analizaron mediante reacción de polimerasa en cadena (RPC). RESULTADOS: El 9,5% (n: 21) de los aislados fueron caracterizados como KPRC, donde se observó una resistencia a colistina de 47,6% (10/21) con valores de CIM50 de 2 μg/mL y CIM90 de > 4 μg/mL. En todos los aislados de KPRC se caracterizó el gen blaKPC y no se detectó el gen mcr-1. El perfil de resistencia observado en otros antimicrobianos fue el siguiente: gentamicina 100% (n: 21), ciprofloxacina 100% (n: 21), cotrimoxazol 100% (n: 21) y amikacina 19% (n: 4). Se observó 100% de sensibilidad a tigeciclina y ceftazidima/avibactam. CONCLUSIÓN: Este estudio demuestra un valor significativo de la resistencia a colistina en comparación a ceftazidima/avibactam y tigeciclina.

BACKGROUND: There is an increase of carbapenem-resistant Klebsiella pneumoniae (CRKP) infections in the pediatric population and epidemiological data are limited. Aim: To calculate the frequency of CRKP in pediatric patients, to determine the in vitro activity of colistin and to detect the presence of mcr-1 gene in said isolates. METHODS: 220 isolates of K. pneumoniae were studied in a pediatric hospital between January 2018 and December 2019. Antimicrobial susceptibility was determined by microdilution in broth according to guidelines of CLSI and EUCAST. The genes blaKPC, blaNDM, blaIMP, blaVIM, blaOXA-48 and mcr-1 were detected by polymerase chain reaction (PCR). RESULTS: 9.5% (n: 21) of the isolates were characterized as CRKP, where was observed a resistance to colistin of 47.6% (10/21) with values of MIC50 of 2 μg/mL and MIC90 of ≥ 4 μg/mL. In 100% of CRKP strains the blaKPC gene was detected and the mcr-1 gene was not found. The resistance profile to other antimicrobials was as follow: gentamicin 100% (n: 21), trimethoprim/sulfamethoxazole 100% (n: 21), ciprofloxacin 100% (n: 21), amikacin 19% (n: 4). All of the isolates were sensitive to ceftazidime/avibactam and tigecycline. CONCLUSION: This study demonstrates a significant value of resistance to colistin in pediatric patients compared to other last line antimicrobial such as ceftazidime/avibactam and tigecycline.

Prevalence of plasmid-mediated quinolone resistance determinants among oxyiminocephalosporin-resistant Enterobacteriaceae in Argentina.

High quinolone resistance rates were observed among oxyiminocephalosporin-resistant enterobacteria. In the present study, we searched for the prevalence of plasmid-mediated quinolone resistance (PMQR) genes within the 55 oxyiminocephalosporin-resistant enterobacteria collected in a previous survey. The main PMQR determinants were aac(6')-Ib-cr and qnrB, which had prevalence rates of 42.4% and 33.3%, respectively. The aac(6')-Ib-cr gene was more frequently found in CTX-M-15-producing isolates, while qnrB was homogeneously distributed among all CTX-M producers.

Comparación de tres métodos microbiológicos para la detección de betalactamasas de espectro extendido en enterobacterias aisladas en Santa Fe (Argentina) / Comparison of three microbiological methods for detection of expanded-spectrum betalactamases in Enterobacteriaceae isolated in Santa Fe (Argentina)

Introducción. Las betalactamasas de espectro extendido (BLEE) son la principal causa de resistencia a las oxiiminocefalosporinas y monobactamas en enterobacterias. La mayoría de las BLEE derivan de TEM o SHV, sin embargo se ha incrementado la incidencia de otras familias como CTX-M, OXA y PER. En Argentina, CTX-M-2 es la BLEE más frecuente en enterobacterias. Esta situación particular, diferente a la del hemisferio norte, ha motivado el estudio de nuevas estrategias diagnósticas que permitan detectar la mayor parte de las BLEE de nuestra región. Métodos. La detección microbiológica de las BLEE se realizó comparando los métodos de sinergia de doble disco, discos de cefotaxima y ceftazidima con y sin el agregado de ácido clavulánico (National Committee for Clinical Laboratory Standards, NCCLS) y discos de cefotaxima y ceftazidima en placas de agar Müeller-Hinton suplementado con clavulanato de litio (MH-cla). Las betalactamasas fueron caracterizadas mediante isoelectroenfoque, perfil de hidrólisis y amplificación por reacción en cadena de la polimerasa. Resultados. Sobre 575 enterobacterias, el 14% fueron resistentes a oxiiminocefalosporinas. En 31 aislados resistentes se detectaron dos tipos diferentes de BLEE: grupo CTX-M-2 (28) y PER-2 (3). El método de sinergia presentó menor sensibilidad en la detección de BLEE que los otros dos métodos. Con ellos se detectó la presencia de BLEE en todos los aislados empleando discos de cefotaxima, sin embargo no ocurrió lo mismo al emplear discos de ceftazidima. Conclusión. El método microbiológico que emplea MH-cla con disco de cefotaxima tuvo una sensibilidad y especificidad equivalentes a la técnica de confirmación propuesta por el NCCLS para la detección de las BLEE empleando el mismo antibiótico (AU)

Introduction. Expanded-spectrum betalactamases (ESBLs) are the main source of resistance to oxyimino cephalosporins and monobactams in Enterobacteriaceae. Most of them derive from TEM or SHV, however the incidence of other families like CTX-M, OXA and PER has increased. In Argentina, the most frequent ESBL in Enterobacteriaceae is CTX-M-2. This specific circumstance, which differs from the situation in the Northern Hemisphere, motivated us to study new diagnostic strategies for the detection of ESBLs in our region. Method. Microbiological ESBL detection was performed by double-disk synergy tests, cefotaxime and ceftazidime disks with and without clavulanic acid (NCCLS), and cefotaxime and ceftazidime disks in Müeller­Hinton agar supplemented with lithium clavulanate (MH-cla). Betalactamases were characterized by isoelectric focusing, hydrolysis profile and PCR amplification. Results. Among 575 clinical isolates of Enterobacteriaceae, 14% were oxyimino cephalosporin-resistant. Two different ESBLs were detected in 31 resistant strains: CTX-M-2 (28) and PER-2 groups (3). The double-disk synergy test was the least sensitive method for ESBL detection. ESBLs were detected by the other two methods in all isolates with the use of cefotaxime disks, but not with ceftazidime disks. Conclusion. The microbiological method employing MH-cla with cefotaxime disks had a sensitivity and specificity comparable to the referral test using the same antibiotic proposed by the NCCLS for the detection of ESBLs (AU)