Comprehensive study reveals phenotypic heterogeneity in Klebsiella pneumoniae species complex isolates.

Here, we conducted a comprehensive analysis of 356 Klebsiella pneumoniae species complex (KpSC) isolates that were classified as classical (cl), presumptive hypervirulent (p-hv) and hypermucoviscous-like (hmv-like). Overall, K. pneumoniae (82.3%), K. variicola (2.5%) and K. quasipneumoniae (2.5%) were identified. These isolates comprised 321 cl-KpSC, 7 p-hv-KpSC and 18 hmv-like-KpSC. A large proportion of cl-KpSC isolates were extended-spectrum-ß-lactamases (ESBLs)-producers (64.4%) and 3.4% of isolates were colistin-resistant carrying carbapenemase and ESBL genes. All p-hv-KpSC showed an antibiotic susceptible phenotype and hmv-like isolates were found to be ESBL-producers (8/18). Assays for capsule production and capsule-dependent virulence phenotypes and whole-genome sequencing (WGS) were performed in a subset of isolates. Capsule amount differed in all p-hv strains and hmv-like produced higher capsule amounts than cl strains; these variations had important implications in phagocytosis and virulence. Murine sepsis model showed that most cl strains were nonlethal and the hmv-like caused 100% mortality with 3 × 108 CFUs. Unexpectedly, 3/7 (42.9%) of p-hv strains required 108 CFUs to cause 100% mortality (atypical hypervirulent), and 4/7 (57.1%) strains were considered truly hypervirulent (hv). Genomic analyses confirmed the diverse population, including isolates belonging to hv clonal groups (CG) CG23, CG86, CG380 and CG25 (this corresponded to the ST3999 a novel hv clone) and MDR clones such as CG258 and CG147 (ST392) among others. We noted that the hmv-like and hv-ST3999 isolates showed a close phylogenetic relationship with cl-MDR K. pneumoniae. The information collected here is important to understand the evolution of clinically important phenotypes such as hypervirulent and ESBL-producing-hypermucoviscous-like amongst the KpSC in Mexican healthcare settings. Likewise, this study shows that mgrB inactivation is the main mechanism of colistin resistance in K. pneumoniae isolates from Mexico.

The Evolution of Antimicrobial Resistance in Mexico During the Last Decade: Results from the INVIFAR Group.

Background: Surveillance of antimicrobial resistance (AMR) requires an international approach with national and local strategies. Our aim was to summarize a retrospective 10-year report of antibiotic resistance of gram-positive and gram-negative bacteria in Mexico. Methods: A total of 46 centers from 22 states of Mexico participated. Databases of AMR from January 2009 to December 2018 were included for most species. The 10-year period was divided into five 2-year periods. Results: For Staphylococcus aureus, a decrease in resistance in all specimens was observed for erythromycin and oxacillin (p < 0.0001 for each). For Enterobacter spp., resistance to meropenem increased for urine specimens (p = 0.0042). For Klebsiella spp., increased drug resistance in specimens collected from blood was observed for trimethoprim/sulfamethoxazole, gentamicin, tobramycin (p < 0.0001 for each), meropenem (p = 0.0014), and aztreonam (p = 0.0030). For Acinetobacter baumannii complex, high drug resistance was detected for almost all antibiotics, including carbapenems, except for tobramycin, which showed decreased resistance for urine, respiratory, and blood isolates (p < 0.0001 for each), and for amikacin, which showed a decrease in resistance in urine specimens (p = 0.0002). An increase in resistance to cefepime was found for urine, respiratory, and blood specimens (p < 0.0001 for each). For Pseudomonas aeruginosa, aztreonam resistance increased for isolates recovered from blood (p = 0.0001). Conclusion: This laboratory-based surveillance of antibiotic resistance shows that resistance is increasing for some antibiotics in different bacterial species in Mexico and highlights the need for continuous monitoring of antibiotic resistance.

A snapshot of antimicrobial resistance in Mexico. Results from 47 centers from 20 states during a six-month period.

AIM: We aimed to assess the resistance rates of antimicrobial-resistant, in bacterial pathogens of epidemiological importance in 47 Mexican centers. MATERIAL AND METHODS: In this retrospective study, we included a stratified sample of 47 centers, covering 20 Mexican states. Selected isolates considered as potential causatives of disease collected over a 6-month period were included. Laboratories employed their usual methods to perform microbiological studies. The results were deposited into a database and analyzed with the WHONET 5.6 software. RESULTS: In this 6-month study, a total of 22,943 strains were included. Regarding Gram-negatives, carbapenem resistance was detected in ≤ 3% in Escherichia coli, 12.5% in Klebsiella sp. and Enterobacter sp., and up to 40% in Pseudomonas aeruginosa; in the latter, the resistance rate for piperacillin-tazobactam (TZP) was as high as 19.1%. In Acinetobacter sp., resistance rates for cefepime, ciprofloxacin, meropenem, and TZP were higher than 50%. Regarding Gram-positives, methicillin resistance in Staphylococcus aureus (MRSA) was as high as 21.4%, and vancomycin (VAN) resistance reached up to 21% in Enterococcus faecium. Acinetobacter sp. presented the highest multidrug resistance (53%) followed by Klebsiella sp. (22.6%) and E. coli (19.4%). CONCLUSION: The multidrug resistance of Acinetobacter sp., Klebsiella sp. and E. coli and the carbapenem resistance in specific groups of enterobacteria deserve special attention in Mexico. Vancomycin-resistant enterococci (VRE) and MRSA are common in our hospitals. Our results present valuable information for the implementation of measures to control drug resistance.

[Nitazoxanide vs albendazole against intestinal parasites in a single dose and for three days]. / Evaluación de la nitazoxanida en dosis única y por tres días en parasitosis intestinal.

OBJECTIVE: To assess the effectiveness of the usual dose of nitazoxanide administered for three days and as a single dose for massive eradication of intestinal parasites in the pediatric population, compared with single-dose albendazole. MATERIAL AND METHODS: A randomized clinical trial was conducted in three rural communities in central Mexico City between 2001 and 2003 to assess three possible therapy regimes in a study population of 786 children 5 to 11 years of age, 92 of whom had a positive parasitology test result (15.1%). Group 1 included 27 patients treated with 400 mg given as a single dose of albendazole; group 2 included 34 patients whose therapy consisted of a 15 mg/kg/day dose for three consecutive days; patients in group 3 (n=31) were administered a single 1.2 g dose of nitazoxanide. Differences in proportions were assessed using Fisher's exact test. RESULTS: No statistically significant differences were found in the effectiveness of the three treatment regimes: 80.5% with albendazole, compared with the two nitazoxanide alternatives (67.6% and 71%, respectively.A higher prevalence of side effects was observed with nitazoxanide in the three-day regimen (26.5%) and as a single dose (32.2%), compared with a single dose of albendazole (7.4%). CONCLUSIONS: According to the evidence on effectiveness and side effects, the use of nitazoxanide is not justified as a massive prophylactic medication for intestinal parasitosis control alternative in endemic areas. In countries with a high prevalence of intestinal parasitosis primary prevention measures should be the most important strategy, together with public sanitation, drinking water and sewage system availability, water chlorination, and appropriate animal fecal waste disposal, as well as health education.

Evaluación de la nitazoxanida en dosis única y por tres días en parasitosis intestinal / Nitazoxanide vs albendazole against intestinal parasites in a single dose and for three days

OBJETIVO: Evaluar la utilidad de nitazoxanida en dosis habitual con esquema de tres días y en dosis única, para la erradicación masiva de parásitos intestinales en la población pediátrica, comparando su efecto con el del albendazol en dosis única. MATERIAL Y MÉTODOS: Se realizó un ensayo clínico aleatorizado, en tres comunidades rurales de la región central de México, durante el periodo 2001-2003, para incluir tres posibles alternativas de tratamiento en 786 sujetos de entre 5 y 11 años de edad, de los cuales 92 tuvieron un examen parasitológico positivo (15.1 por ciento). El grupo 1 incluyó 27 pacientes que recibieron 400 mg de albendazol en dosis única; el grupo 2 incluyó 34 pacientes a quienes se administró nitazoxanida en dosis de 15 mg/kg/día durante tres días consecutivos; y el grupo 3 incluyó 31 pacientes que recibieron 1.2 g de nitazoxanida en dosis única. Se evaluó diferencia de proporciones mediante prueba exacta de Fisher. RESULTADOS: No existieron diferencias estadísticamente significativas en la efectividad de los tres esquemas de tratamiento: (80.5 por ciento) con albendazol, comparado con las dos alternativas adicionales de nitazoxanida (67.6 por ciento y 71 por ciento, respectivamente). Se observó una mayor prevalencia de efectos secundarios con nitazoxanida por kg /día (26.5 por ciento) y en dosis única (32.2 por ciento), en comparación con la dosis única de albendazol (7.4 por ciento). CONCLUSIONES: Las evidencias en cuanto a la efectividad y elevada prevalencia de efectos secundarios de la nitazoxanida no justifican aún su utilización como quimiopreventivo masivo para el control de parasitosis intestinal en áreas endémicas. En países con elevada prevalencia de parasitosis intestinal las medidas de prevención primaria que continúan vigentes, y que deben priorizarse, están relacionadas con sanidad pública, introducción de agua potable y drenaje, cloración de agua y manejo adecuado de excretas de animales domésticos, así como educación para la salud.

Hemoglobin measured by Hemocue and a reference method in venous and capillary blood: a validation study.

OBJECTIVE: To assess the comparability of hemoglobin concentration (Hb) in venous and capillary blood measured by Hemocue and an automated spectrophotometer (Celldyn) and to document the influence of type of blood (capillary or venous) and analysis method on anemia prevalence estimates. MATERIAL AND METHODS: Between February and May 2000, capillary and venous samples were collected from 72 adults and children at Hospital del Niño Morelense (Morelos State Children's Hospital) in Cuernavaca, Morelos, Mexico, and assessed for Hb using the Hemocue and Celldyn methods. Estimated Hb levels were compared using the concordance correlation coefficient and Student's t test for paired data. The sensitivity and specificity for anemia diagnosis were estimated and compared between type of blood and method of assessment. RESULTS: Capillary blood had higher Hb (+0.5 g/dl) than venous blood in adults and children, as did samples assessed by Celldyn compared to Hemocue (+0.3 g/dl). Specificity to detect anemia was adequate (> 0.90) but sensitivity was low for capillary blood assessed by Hemocue (< 0.80). CONCLUSIONS: The difference in Hb between venous and capillary blood is likely related to biological variability. Hemoglobin concentration in capillary blood assessed by Hemocue provides an adequate estimation of population anemia prevalence but may result in excess false negative diagnoses among individuals. The results of this study stress the importance of sample collection technique, particularly for children. Method of analysis and sampling site need to be taken into consideration in field studies. The English version of this paper is available too at: http://www.insp.mx/salud/index.html.

Hemoglobin measured by Hemocue and a reference method in venous and capillary blood: a validation study

Objective. To assess the comparability of hemoglobin concentration (Hb) in venous and capillary blood measured by Hemocue and an automated spectrophotometer (Celldyn) and to document the influence of type of blood (capillary or venous) and analysis method on anemia prevalence estimates. Material and Methods. Between February and May 2000, capillary and venous samples were collected from 72 adults and children at Hospital del Niño Morelense (Morelos State Children's Hospital) in Cuernavaca, Morelos, Mexico, and assessed for Hb using the Hemocue and Celldyn methods. Estimated Hb levels were compared using the concordance correlation coefficient and Student's t test for paired data. The sensitivity and specificity for anemia diagnosis were estimated and compared between type of blood and method of assessment. Results. Capillary blood had higher Hb (+0.5g/dl) than venous blood in adults and children, as did samples assessed by Celldyn compared to Hemocue (+0.3g/dl). Specificity to detect anemia was adequate (>0.90) but sensitivity was low for capillary blood assessed by Hemocue (<0.80). Conclusions. The difference in Hb between venous and capillary blood is likely related to biological variability. Hemoglobin concentration in capillary blood assessed by Hemocue provides an adequate estimation of population anemia prevalence but may result in excess false negative diagnoses among individuals. The results of this study stress the importance of sample collection technique, particularly for children. Method of analysis and sampling site need to be taken into consideration in field studies.

Objetivo. Evaluar la comparabilidad de la concentración de hemoglobina (Hb) en sangre venosa y capilar medida por Hemocue y por espectrofotómetro automatizado (Celldyn), así como documentar la influencia del tipo de sangre (capilar o venosa) y del método de análisis sobre la prevalencia de anemia. Material y métodos. De febrero a mayo de 2000, se recolectaron muestras de sangre capilar y venosa en 72 adultos y niños en el Hospital del Niño Morelense, Cuernavaca, Morelos, México. Se determinaron los niveles de Hb con los métodos Hemocue y Celldyn. Las cifras de Hb estimadas se compararon con el coeficiente de concordancia y la prueba pareada de t de Student. También se comparó la sensibilidad y especificidad para el diagnóstico de anemia, utilizando sangre de los dos tipos y métodos de análisis. Resultados. La Hb fue mayor en sangre capilar comparada con sangre venosa (+0.5g/dl) en adultos y niños, y en las determinaciones por Celldyn comparadas con las de Hemocue (+0.3 g/dl). La especificidad para el diagnóstico de anemia fue adecuada (>0.90), mientras que la sensibilidad fue baja para las muestras capilares medidas por Hemocue (<0.80). Conclusiones. Es probable que la diferencia en la Hb entre sangre venosa y capilar refleje variabilidad biológica. La Hb en sangre capilar medida por Hemocue provee una estimación adecuada de la prevalencia de anemia en poblaciones, pero podría resultar en un exceso de diagnósticos falsos negativos. Los resultados de este estudio ponen énfasis en la importancia de la técnica de recolección de la muestra, particularmente en niños. Los métodos de análisis y tipos de muestra de sangre deben ser tomados en cuenta en estudios de campo.