The effect of the efflux pump inhibitor Carbonyl Cyanide m-Chlorophenylhydrazone (CCCP) on the susceptibility to imipenem and cefepime in clinical strains of Acinetobacter baumannii.

INTRODUCTION: In the last years the rapid expansion of multidrug-resistant A. baumannii strains have become a major health problem. Efflux pumps are a group of transport proteins that contribute to the development of antibiotic resistance. The aim of this study was to evaluate the effect of the efflux pump inhibitor carbonyl cyanide 3-chlorophenylhydrazone (CCCP) on the antimicrobial action of imipenem and cefepime on clinical strains of A. baumannii. MATERIALS AND METHODS: A total of 49 non-duplicate clinical samples were collected during January through December of 2018 from patients hospitalized in the Hospital Regional Docente de Cajamarca. Of the 49 samples obtained, the confirmatory identification of A. baumannii was performed on 47 samples by molecular methods. The amplification of the blaOXA-51-like gene was carried out by polymerase chain reaction (PCR). The determination of the minimum inhibitory concentration (MIC) was calculated using the microdilution method in culture broth. The susceptibility to both antibiotics (cefepime and imipenem) was evaluated in the presence and absence of the inhibitor carbonyl cyanide 3-chlorophenylhydrazone (CCCP). RESULTS: A total of 47 strains of A. baumannii were isolated: 97.87% (46/47) were resistant to Imipenem, 2.13% (1/47) of them were classified as intermediate and none of these strains were susceptible. On the other hand, 51.06% (24/47) of isolates were resistant to cefepime; 19.15% (9/47) intermediate and 29.79% (14/47) susceptible. We considered a significant difference in antibiotic susceptibility if the MIC changed at least 4 dilutions, after the addition of the inhibitor. In the case of CCCP in addition to imipenem, 2.1% (1/47) had a significant change of 4 or more reductions in MIC, 59.6% (28/47) achieved a change equal or less than 3 dilutions and 17.0% (8/47) did not have any change. In the case of CCCP with cefepime the percentage of strains with the significant change of MIC was 8.5% (4/47). On the other hand, 53.2% (24/47) presented a reduction equal or less than 3 dilutions and 12.8% (6/47) did not show changes. CONCLUSION: In conclusion, our results demonstrate that the use of CCCP may improve the antibiotic effect of imipenem and cefepime on clinical strains of A. baumannii. The relevance of this study is that it provides evidence that this efflux pump inhibitor may be an alternative treatment against multidrug-resistant A. baumannii.

Susceptibilidad a betalactámicos y resistencia por betalactamasas de espectro extendido (BLEE) enEnterobacteriaceae aisladas de reservorios ambientales de un hospital general en Cajamarca, Perú / Beta-lactam susceptibility and resistance by extended spectrum beta-lactamases (ESBL) in Enterobacteriaceae environmental isolations at a general hospital in Cajamarca, Peru

Objetivos: Identificar enterobacterias en reservorios intrahospitalarios, evaluar su sensibilidad a betalactámicos y determinar su capacidad de producir betalactamasas de espectro extendido (BLEE), en el Hospital Regional de Cajamarca. Material y métodos: Se obtuvieron muestras mediante hisopado de grifos, lavatorios, mesas, camas y tablillas de historia clínica en las áreas de cirugía y pediatría; se recuperaron, aislaron e identificaron 45 cultivos de importancia clínica: 14 Enterobacter cloacae, 11 Escherichia coli, 5 Citrobacter freundii, 4 Klebsiella pneumoniae y 11 de otros géneros. Se determinó la sensibilidad antimicrobiana a los antibióticos betalactámicos: ampicilina, cefalotina, cefoxitina, ceftazidima, cefotaxima, ceftriaxona, amoxicilina-clavulanato, aztreonam e imipenem. Teniendo en cuenta los diámetros críticos de tamizaje, se realizó el test confirmatorio para BLEE. Para el análisis estadístico se utilizó el programa estadístico SPSS v15. Resultados: De los 45 cultivos aislados 34 fueron resistentes a ampicilina, 34 a cefalotina, 14 a cefoxitina, 12 a cefotaxima, 11 a ceftriaxona, 5 a ceftazidima, 19 a amoxicilina-clavulanato y 15 a aztreonam. Doce cultivos presentaron resistencia por BLEE a cefalosporinas de tercera generación y/o monobactámicos, cuatro E. coli y cuatro E. cloacae fueron los más relevantes. Todos fueron sensibles a imipenem. Conclusiones: Dada la capacidad de algunos de estos cultivos de producir BLEE existe el riesgo de brotes intrahospitalarios que pueden complicarse cuando son originados por microorganismos multirresistentes. La producción de BLEE como mecanismo de resistencia en los cultivos hallados debe ser motivo de preocupación por las implicancias que tiene.

Objectives: To identify enterobacteria cultures in nosocomial reservoirs, assess their sensitivity to beta-lactams and their ability to produce extended-spectrum beta-lactamases (ESBLs) at the Hospital Regional de Cajamarca. Material and methods: Samples were collected by cotton swab in faucets, sinks, tables, beds and patientsÆ medical charts in the areas of surgery and pediatrics, 45 cultures clinically important were recovered, isolated and identified: 14 Enterobacter cloacae, 11 Escherichia coli, 5 Citrobacter freundii, 4 Klebsiella pneumoniae and 11 the other genres. An antimicrobial susceptibility test was performed for beta-lactamic antibiotics: ampicillin, cephalothin, cefoxitin, ceftazidime, cefotaxime, ceftriaxone, amoxicillin-clavulanate, aztreonam and imipenem. Given the critical diameters of screening, the confirmatory test for ESBL was performed. For statistical analysis, were used SPSS v15. Results: Of the 45 cultures isolate, 34 were resistant to ampicillin, 34 to cephalothin, 14 to cefoxitin, 12 to cefotaxime, 11 to ceftriaxone, 5 to ceftazidime, 19 to amoxicillin-clavulanate and 15 to aztreonam. Twelve cultures were resistant to third-generation cephalosporins and monobactams for ESBLs, four E. coli and four E. cloacae were the most relevant. All were sensitive to imipenem. Conclusions: Given the ability of some of these cultures to produce ESBL, there is a risk of nosocomial outbreaks that can be complicated when are caused by multiresistant organisms. ESBL production as a resistance mechanism in cultures found cause concern.

Frecuencia de aislamientos ambientales de Staphylococcus aureus y su actividadbeta-lactamasa en un hospital de Cajamarca, Perú / Frequency of Staphylococcus aureus environmental isolations and beta-lactamase activity at a hospital of Cajamarca, Perú

Objetivo. Determinar la frecuencia de aislamientos de Staphylococcus aureus y su capacidad para producir beta-lactamasas clásicas, en reservorios ambientales de las salas de operaciones del Servicio de Cirugía y de las salas de partos del Servicio de Obstetricia del Hospital Regional de Cajamarca, Perú. Metodología. Las muestras analizadas para el presente estudio fueron obtenidas mediante hisopados de las superficies del mobiliario y de otros objetos inanimados que se encontraban en las salas. Para el aislamiento e identificación se empleó agar selectivo manitol salado, coloración Gram y las pruebas de catalasa y coagulasa. Para la determinación de beta-lactamasas clásicas, se empleó el método yodométrico. Resultados. De 64 muestras, se obtuvieron 17 aislamientos identificados como S. aureus, de los cuales, 3 fueron productores de betalactamasas clásicas y fueron hallados en reservorios tipo camillas y mesas. Conclusiones. La investigación demuestra una moderada frecuencia de S. aureus con capacidad de producir beta-lactamasa y, por lo tanto, potencialmente multirresistente, en reservorios ambientales hospitalarios.

Objetive: To determine the frequency of Staphylococcus aureus isolates, and its capacity to produce classic beta-lactamases, in environmental fomites in operations rooms and delivery rooms at the Hospital Regional de Cajamarca, Perú. Methods: Analyzed samples for the present study were obtained by cottons swabs from furniture surfaces and other inanimate objects that were in the rooms. Mannitol salt agar, Gram coloration, catalase and coagulase tests were used for starin isolation and identification. The iodometric method was used for the determination of classic beta-lactamases. Results: Out of 64 samples, 17 isolates were obtained and identified as S. aureus, 3 of which were producing classic beta-lactamases and were found in fomites from stretchers and tables. Conclusions: This study showed a moderate frequency of S. aureus with capacity to produce beta-lactamases, potentially multiresistant, in environmental fomites at the hospital.

Pseudomonas aeruginosa productora de betalactamasa clásica y de espectro extendido en reservorios de un servicio de Neonatología / Pseudomonas aeruginosa PRODUCING classic and extended spectrum beta-lactamases in neonatology reservoirs

Para determinar la frecuencia de Pseudomonas aeruginosa productoras de betalactamasa clásica (BLC) y de espectro extendido (BLEE) en reservorios del servicio de neonatología del Hospital Regional de Cajamarca, entre noviembre del 2005 y febrero del 2006, se obtuvieron muestras mediante hisopados a partir de lavatorios, grifería, incubadoras, cunas, etc. que se encontraban en el servicio. Se empleó el medio agar cetrimide, coloración Gram y las pruebas de oxidasa y del citrato para el aislamiento e identificación de P.aeruginosa. Se utilizaron los métodos yodométrico para la determinación de BLC y de sinergia con doble disco para detectar BLEE. De 97 muestras se obtuvieron 20 aislamientos de P. aeruginosa (21 por ciento); de éstos 45 por ciento (9/20) fueron productoras de BLC, halladas en reservorios de uso común como lavatorios y grifos, sólo el 10 por ciento (2/20) fueron productoras de BLEE. Existe el riesgo de infecciones por P. aeruginosa productoras de BLC y BLEE en el servicio de neonatología evaluado.

To determine frequency of Pseudomonas aeruginosa producing classic and extended spectrum beta-lactamases in neonatology service reservoirs at Regional Hospital of Cajamarca, between november 2005 and february 2006, samples were obtained using cotton buds from sinks, water taps, incubators, cradles, etc. that were in the service. Cetrimide agar, Gram coloration, oxidase and citrate tests were used for isolation and identification of P. aeruginosa. Yodometric method was used for determination of classic beta-lactamases and synergy with double disk to detect extended spectrum beta-lactamases. From 97 samples 20 P. aeruginosa isolations were obtained (21 per cent); of these 45 per cent (9/20) were producing of classic beta-lactamases, that were found in reservoirs of common use as sinks and water taps, only 10 per cent (2/20) were producers of extended spectrum beta-lactamases. In valued neonatology service there is risk of infections for P. aeruginosa producing classic and extended spectrum beta-lactamases.