Detection of Plasmid-Mediated Resistance against Colistin in Multi-Drug-Resistant Gram-Negative Bacilli Isolated from a Tertiary Hospital.

The aim of this study was to determine the prevalence of plasmid-mediated colistin resistance mcr-1 to mcr-5 genes among colistin and multi-drug-resistant Gram-negative bacilli strains isolated from patients in a tertiary hospital in Toluca, Mexico. The presence of mcr genes among the 241 strains collected was assessed by PCR. In the case of mcr-carrying E. coli, further PCR tests were performed to determine the presence of blaCTX-M and whether the strains belonged to the O25b-ST131 clone. Conjugation experiments were also carried out to assess the horizontal transmission of colistin resistance. A total of twelve strains (5.0%), of which four were E. coli; four were P. aeruginosa; three were K. pneumoniae, and one E. cloacae, were found to be resistant to colistin. Of these strains, two E. coli isolates were found to carry mcr-1, and Southern blot hybridization demonstrated its presence on an approximately 60 kb plasmid. Both mcr-1-carrying E. coli strains were found to co-express blaCTX-M, belong to the O25b-ST131 clone, and horizontally transmit their colistin resistance. The results of this study confirm the presence of plasmid-mediated colistin resistance in hospitalized patients in Mexico and demonstrated that the multi-drug-resistant O25b-ST131 E. coli clone can acquire mcr genes and transmit such resistance traits to other bacteria.

Active Surveillance of Antimicrobial Resistance and Carbapenemase-Encoding Genes According to Sites of Care and Age Groups in Mexico: Results from the INVIFAR Network.

We analyzed the antimicrobial resistance (AMR) data of 6519 clinical isolates of Escherichia coli (n = 3985), Klebsiella pneumoniae (n = 775), Acinetobacter baumannii (n = 163), Pseudomonas aeruginosa (n = 781), Enterococcus faecium (n = 124), and Staphylococcus aureus (n = 691) from 43 centers in Mexico. AMR assays were performed using commercial microdilution systems (37/43) and the disk diffusion susceptibility method (6/43). The presence of carbapenemase-encoding genes was assessed using PCR. Data from centers regarding site of care, patient age, and clinical specimen were collected. According to the site of care, the highest AMR was observed in E. coli, K. pneumoniae, and P. aeruginosa isolates from ICU patients. In contrast, in A. baumannii, higher AMR was observed in isolates from hospitalized non-ICU patients. According to age group, the highest AMR was observed in the ≥60 years age group for E. coli, E. faecium, and S. aureus, and in the 19-59 years age group for A. baumannii and P. aeruginosa. According to clinical specimen type, a higher AMR was observed in E. coli, K. pneumoniae, and P. aeruginosa isolates from blood specimens. The most frequently detected carbapenemase-encoding gene in E. coli was blaNDM (84%).

Emergence of Fosfomycin Resistance by Plasmid-Mediated fos Genes in Uropathogenic ESBL-Producing E. coli Isolates in Mexico.

Fosfomycin is currently a viable option against urinary tract infections, particularly against extended-spectrum ß-lactamases (ESBL)-producing E. coli, due to its unique mechanism of action and its low resistance among bacteria. The objective of this study was to investigate two of the three most common mechanisms of resistance against this antibiotic among 350 ESBL-producing E. coli strains isolated from the urine of Mexican patients. The prevalence of fosfomycin resistance in our study was 10.9% (38/350). Of all resistant isolates analyzed, 23 (60.5%) were identified as fos-producing organisms, with 14 strains carrying fosA3 and 9, fosA1. Additionally, 11 (28.9%) fosfomycin-resistant isolates presented resistance due to impaired antibiotic transport and 8 (21.0%) both mechanisms. No resistance mechanism investigated in the study was found on 12 strains. All 38 confirmed ESBL-producing isolates carried a blaCTX-M subtype, 36 (94.5%) belonged to the O25b-ST131 clone, and all of them were able to transfer the fosfomycin resistance trait to recipient strains horizontally. This is the first study in Mexico demonstrating a plasmid-mediated fosfomycin resistance mechanism among clinical E. coli strains. Since our results suggest a strong association among fos and blaCTX-M genes and ST131 clones in uropathogenic E. coli, plasmid-mediated fosfomycin resistance should be closely monitored.

Increment Antimicrobial Resistance During the COVID-19 Pandemic: Results from the Invifar Network.

Aim: This study aims to assess the changes in antimicrobial resistance among some critical and high-priority microorganisms collected previously and during the coronavirus disease 2019 (COVID-19) pandemic in Mexico. Methods: We collected antimicrobial susceptibility data for critical and high-priority microorganisms from blood, urine, respiratory samples, and from all specimens, in which the pathogen may be considered a causative agent. Data were stratified and compared for two periods: 2019 versus 2020 and second semester 2019 (prepandemic) versus the second semester 2020 (pandemic). Results: In the analysis of second semester 2019 versus the second semester 2020, in blood samples, increased resistance to oxacillin (15.2% vs. 36.9%), erythromycin (25.7% vs. 42.8%), and clindamycin (24.8% vs. 43.3%) (p ≤ 0.01) was detected for Staphylococcus aureus, to imipenem (13% vs. 23.4%) and meropenem (11.2% vs. 21.4) (p ≤ 0.01), for Klebsiella pneumoniae. In all specimens, increased ampicillin and tetracycline resistance was detected for Enterococcus faecium (p ≤ 0.01). In cefepime, meropenem, levofloxacin, and gentamicin (p ≤ 0.01), resistance was detected for Escherichia coli; and in piperacillin-tazobactam, cefepime, imipenem, meropenem, ciprofloxacin, levofloxacin, and gentamicin (p ≤ 0.01), resistance was detected for Pseudomonas aeruginosa. Conclusion: Antimicrobial resistance increased in Mexico during the COVID-19 pandemic. The increase in oxacillin resistance for S. aureus and carbapenem resistance for K. pneumoniae recovered from blood specimens deserves special attention. In addition, an increase in erythromycin resistance in S. aureus was detected, which may be associated with high azithromycin use. In general, for Acinetobacter baumannii and P. aeruginosa, increasing resistance rates were detected.

Drug resistance phenotypes and genotypes in Mexico in representative gram-negative species: Results from the infivar network.

AIM: This report presents phenotypic and genetic data on the prevalence and characteristics of extended-spectrum ß-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, blaTEM, blaSHV, and blaCTX were detected in 68.79%, 72.3%, and 91.9% of isolates, respectively. Among E. coli isolates, blaTEM, blaSHV, and blaCTX were detected in 20.8%, 4.53%, and 85.7% isolates, respectively. For both species, the most frequent genotype was blaCTX-M-15. Among Enterobacteriaceae, the most frequently detected carbapenemase-encoding gene was blaNDM-1 (81.5%), followed by blaOXA-232 (14.8%) and blaoxa-181(7.4%), in A. baumannii was blaOXA-24 (76%) and in P. aeruginosa, was blaIMP (25.3%), followed by blaGES and blaVIM (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 blaCTX-M-15 exists in both E. coli and K. pneumoniae.

The estimation of uncertainty of measurement of glycated hemoglobin as an analytical performance specification and in the interpretation of its results.

BACKGROUND: Glycated hemoglobin (HbA1c) plays a key role in monitoring the glycemic state of an individual. Uncertainty of measurement (U) indicates the magnitude of the doubt about a measurement result. To properly classify an individual as under either good or poor glycemic control, it has been suggested that U of an HbA1c result should not exceed ±0.5%. METHODS: The statistical method used to calculate uncertainty of measurement was the "top down" approach suggested by EURACHEM/CITAC. This approach allows the inclusion of imprecision, bias, uncertainty of bias and uncertainty of the calibration of the HbA1c method. The value of bias was obtained using data generated from the external quality assessment of the Randox International Quality Assessment Scheme and that of the Unity data management software system. Imprecision was calculated after the daily analysis of two levels of control sera. RESULTS: Calculation of uncertainty of measurement of HbA1c was a straightforward procedure used to calculate U. Due to the different bias results obtained using two different external quality programs, the results of U were significantly different (±0.19% vs ±â€¯0.43%) from each other; however, in both cases, the U results were below the maximal suggested uncertainty of ±0.5%. CONCLUSIONS: The calculation of U of HbA1c by the EURACHEM/CITAC method is a practical approach that can be used as an additional analytical goal in the measurement of HbA1c. In addition, this information can aid clinicians to determine the level of confidence that can be placed in the test results.

[Molecular characterization and antimicrobial susceptibility pattern of extended-spectrum ß-lactamase-producing Escherichia coli as cause of community acquired urinary tract infection]. / Caracterización molecular y patrón de susceptibilidad antimicrobiana de Escherichia coli productora de ß-lactamasas de espectro extendido en infección del tracto urinario adquirida en la comunidad.

Background Community acquired urinary tract infections (CaUTI) caused by strains of extended-spectrum ß-lactamases (ESBL) - producing Escherichia coli, mainly by strains carrying the blaCTX-M-15 gene, is a growing phenomenon worldwide. Aim To determine the antibiotic susceptibility pattern of ESBL-producing E. coli as cause of CaUTI and to identify their molecular pattern. Methods A descriptive study was performed in the city of Oaxaca, Mexico, from where 288 strains of CaUTI-producing strains of E. coli in adults with possible UTI were isolated. The CLSI criteria was followed to determine the antimicrobial susceptibility patterns, and their molecular characterization was performed by using PCR. Results 31.3% of E. coli strains isolated in our population were ESBL producers, which presented higher levels of antibiotic resistance than those of non-producers of these enzymes. 95.6% of the studied strains were carriers of the blaCTX-M gene. Conclusions One-third of the Ca-UTI caused by E. coli in our population are caused by ESBL-producing strains, which present high levels of resistance to the antibiotics widely used in our community. This situation considerably decreases the number of antibiotics available for an empiric treatment against these infections.

Caracterización molecular y patrón de susceptibilidad antimicrobiana de Escherichia coli productora de β -lactamasas de espectro extendido en infección del tracto urinario adquirida en la comunidad / Molecular characterization and antimicrobial susceptibility pattern of extended-spectrum β -lactamase-producing Escherichia coli as cause of community acquired urinary tract infection

Resumen Introducción Las infecciones del tracto urinario adquiridas en la comunidad (ITUac) causadas por cepas de Escherichia coli productoras de β-lactamasas de espectro extendido (BLEE), principalmente por cepas que contienen el gen blaCTX-M-15, es un fenómeno creciente a nivel mundial. Objetivo Determinar el patrón de susceptibilidad a antimicrobianos de cepas de E. coli productoras de BLEE causantes de ITUac y conocer su patrón molecular. Materiales y Métodos Se realizó un estudio descriptivo en Oaxaca, México, donde se incluyeron 288 cepas de E. coli aisladas de pacientes adultos con posible ITUac. Para obtener los patrones de susceptibilidad antimicrobiana se siguieron los criterios del CLSI y para obtener el análisis molecular se utilizó la técnica de RPC. Resultados Del total de cepas de E. coli aisladas, 31,3% fueron productoras de BLEE, presentando una menor susceptibilidad a antimicrobianos que las cepas no productoras de estas enzimas. El 95,6% de las cepas BLEE estudiadas fueron portadoras del gen blaCTX-M. Conclusiones Un tercio de las ITUac causadas por E. coli en nuestra población fueron causadas por cepas BLEE, mostrando un alto nivel de resistencia a los antimicrobianos comúnmente utilizados en su tratamiento y disminuyendo las opciones terapéuticas para tratamientos empíricos en esta población.

Background Community acquired urinary tract infections (CaUTI) caused by strains of extended-spectrum β-lactamases (ESBL) - producing Escherichia coli, mainly by strains carrying the blaCTX-M-15 gene, is a growing phenomenon worldwide. Aim To determine the antibiotic susceptibility pattern of ESBL-producing E. coli as cause of CaUTI and to identify their molecular pattern. Methods A descriptive study was performed in the city of Oaxaca, Mexico, from where 288 strains of CaUTI-producing strains of E. coli in adults with possible UTI were isolated. The CLSI criteria was followed to determine the antimicrobial susceptibility patterns, and their molecular characterization was performed by using PCR. Results 31.3% of E. coli strains isolated in our population were ESBL producers, which presented higher levels of antibiotic resistance than those of non-producers of these enzymes. 95.6% of the studied strains were carriers of the blaCTX-M gene. Conclusions One-third of the Ca-UTI caused by E. coli in our population are caused by ESBL-producing strains, which present high levels of resistance to the antibiotics widely used in our community. This situation considerably decreases the number of antibiotics available for an empiric treatment against these infections.

Aplicación de metas analíticas y modelo Seis Sigma en la evaluación del control de calidad de Química Clínica / Application of clinical goals and the Six Sigma model in the evaluation of quality control in Clinical Chemistry

Introducción. Con el objetivo de asegurar la confiabilidad de sus resultados, los laboratorios de análisis clínicos deben implementar un programa de control de calidad interno suficientemente bueno para alcanzar metas analíticas con los mayores estándares posibles. Materiales y métodos. Se realizó un estudio retrospectivo, descriptivo y longitudinal. Para este estudio se emplearon los resultados del control de calidad interno del área de Química Clínica de un laboratorio mexicano obtenidos en el periodo comprendido entre julio y diciembre del 2016. Resultados. Para el 100% de los analitos en estudio se alcanzaron las metas de error total máximo permitido establecidas por el Clinical Laboratory Improvement Amendments. En cuanto a las metas basadas en variabilidad biológica, se demostró el alcance de metas deseables u óptimas en 89% de los analitos estudiados, obteniéndose resultados inferiores en aquellos analitos con bajo índice de variabilidad biológica. Finalmente, en cuanto a los resultados de la sigmametría, los resultados son muy variados dependiendo de las metas analíticas utilizadas, obteniéndose los valores sigma más bajos en cuanto menor es la variabilidad biológica del analito estudiado. Conclusiones. Sobre la base de nuestros resultados podemos indicar que un modelo de control de calidad adecuado en Química Clínica pudiera incluir inicialmente el establecimiento de metas analíticas utilizando el modelo de CLIA para aquellos analitos con baja variabilidad biológica y el modelo de variabilidad biológica en metas deseables para el resto de los analitos. Con los instrumentos utilizados en este estudio, es factible alcanzar dichas metas (AU)

Introduction. With the aim of providing clinically relevant results, the clinical laboratory must implement a sufficiently good internal quality control system in order to achieve analytical goals with the highest possible standards. Materials and methods. A retrospective, descriptive, and longitudinal study was performed in order to study the internal quality control results of the Clinical Chemistry area of a Mexican laboratory obtained during the period from July to December 2016. Results. The Clinical Laboratory Improvement Amendments (CLIA) goals of maximum total allowable error were achieved in 100% of the analytes studied. In the case of biological variation goals, desirable or optimal goals were achieved for in 89% of the analytes studied, with inferior results being obtained in these analytes with a low biological variability index. Finally, as regards the results of sigma values, our results varied considerably depending on the analytical specifications used, achieving the lowest values in those analytes with the lowest biological variability index. Conclusions. Based on our results we can suggest that an adequate quality control model in Clinical Chemistry could initially include the establishment of analytical specifications based on CLIA for those analytes with low biological variation, and the desirable goals of biological variation for the rest of the analytes. Both goals can be achieved by the instruments used in this study (AU)