Anti-fungal efficacy of combination of amphotericin B with colistin and gentamicin in McCarey-Kaufman corneal preservation medium

Purpose: To curtail the potential of donor corneal tissue disseminating fungi to the recipient抯 eye, we evaluated the addition of amphotericin B to McCarey?Kaufman (M?K)梒orneal storage medium supplemented with colistin. Methods: Amphotericin B was examined for its ability to inhibit the growth of Candida albicans and Aspergillus flavus using a microbroth dilution test and checkerboard assay in combination with only gentamicin and a combination of colistin, gentamicin, and amphotericin B. The safety on epithelium and endothelium was evaluated by 3?(4,5?dimethylthiazol?2?yl)?2, 5?diphenyltetrazolium bromide (MTT) assay. Results: The minimal inhibitory concentration of gentamicin was found to be >256 ?g/ml against both C. albicans and A. flavus, whereas that of amphotericin B was found to be in a range of 0.25�5 and 1�?g/ml for C. albicans and A. flavus, respectively. According to the checkerboard assay, 80% (4/5) of C. albicans isolates and 100% (5/5) of A. flavus isolates responded synergistically to the combination of amphotericin B and gentamicin, but only 20% (1/5) of C. albicans isolates showed an additive effect. None of the tested isolates displayed antagonism. The combined effect of the three drugs also did not display any antagonistic effect. Additionally, the MTT assay reveals no toxic effect of the antimicrobials used on corneal epithelial and endothelial cells. Conclusion: In vitro experiments demonstrate that amphotericin B is not toxic to either epithelium or endothelium and is a promising additive to the M?K medium supplemented with colistin.

Use of topical colistin in bacterial keratitis caused by extensively drug-resistant Pseudomonas Aeruginosa: a case report / Uso de colistina tópica em ceratite bacteriana causada por Pseudomonas Aeruginosa extensivamente resistente a medicamentos: relato de caso

ABSTRACT Bacterial keratitis caused by multidrug-resistant strains of Pseudomonas aeruginosa is a therapeutic challenge due to a limited number of active antimicrobials and rapid progression to corneal necrosis and perforation. To report the use of topical colistin and surgical tarsorrhaphy in a case of keratitis caused by extensively drug-resistant Pseudomonas aeruginosa in a patient with severe coronavirus disease-2019 (COVID-19) pneumonia. A 56-year-old male was admitted to the intensive care unit with clinical symptoms of severe COVID-19 pneumonia. During his stay in the unit, he developed rapidly progressive keratitis with Pseudomonas aeruginosa resistant to all drugs except for colistin on culture. Due to incomplete lid closure, a temporary tarsorrhaphy was performed, and a regimen of descending-dose topical colistin was initiated. After five weeks, keratitis resolved completely. Extensively drug-resistant Pseudomonas aeruginosa is an unusual cause of bacterial keratitis. We describe the safe and effective use of topical colistin in a case with severe corneal involvement.

RESUMO A ceratite bacteriana causada por cepas multirresistentes de Pseudomonas aeruginosa é um desafio terapêutico, devido à disponibilidade limitada de antimicrobianos e à rápida progressão para necrose e perfuração da córnea. O objetivo deste artigo é relatar o uso de colistina tópica e tarsorrafia cirúrgica em um caso de ceratite por Pseudomonas aeruginosa amplamente resistente a medicamentos em um paciente com pneumonia grave por COVID19. Um homem de 56 anos foi internado em uma unidade de terapia intensiva com sintomas clínicos de pneumonia grave por COVID19. Durante sua permanência na unidade de terapia intensiva, o paciente desenvolveu uma ceratite rapidamente progressiva, cuja cultura foi positiva para Pseudomonas aeruginosa resistente a todos os antimicrobianos, exceto colistina. Devido ao fechamento incompleto da pálpebra, foi realizada uma tarsorrafia temporária e foi instituído um esquema de colistina tópica em doses decrescentes. Após cinco semanas, a resolução completa da ceratite foi alcançada. Pseudomonas aeruginosa amplamente resistente a medicamentos é uma causa incomum de ceratite bacteriana. Este relato descreve o uso seguro e eficaz da colistina tópica em um caso com comprometimento corneano grave.

Caracterización de la utilización de colistín en un hospital de alta complejidad

Resumen: El aumento de la resistencia y la escasez de nuevos antibacterianos ha requerido la reintroducción de antiguos antimicrobianos entre ellos colistín. Objetivo: Caracterizar la utilización de colistín durante el año 2017 en un hospital universitario, mediante la descripción de los pacientes, los tratamientos, la microbiología asociada y efectos adversos. Pacientes y Métodos: Trabajo observacional retrospectivo. Se revisaron los datos de todos los pacientes que recibieron colistín intravenoso (IV) por al menos 48 horas, durante el año 2017. Resultados: Se incluyeron 53 pacientes, equivalentes a 91 tratamientos. El foco respiratorio fue el principal (46,2%). El 68,1% de los tratamientos fue iniciado en la UCI. La mayoría de los pacientes tenía una hospitalización reciente (83,5%), y presentaban uso previo de antibacterianos (89%). Los dos patógenos mayoritariamente identificados fueron Pseudomonas aeruginosa y Klebsiella spp. El consumo promedio de colistín fue de 2,4 DDD/100 camas/día. El servicio que más consumió colistín fue la UCI, con 45,5 DDD/100 camas/día, usando generalmente la dosis de 3 MUI cada 8 horas IV y con una baja utilización de dosis de carga. Conclusión: Colistín corresponde a un antimicrobiano de uso restringido a infecciones sospechadas o confirmadas por agentes bacterianos multi resistentes. En esta serie, su uso inicial fue principalmente empírico, en pacientes con factores de riesgo para resistencia antibacteriana; se usó en forma asociada a otros antimicrobianos, siendo el foco principal el respiratorio.

Background: The increase in resistance and the shortage of new antibiotics has led to the reintroduction of old antimicrobials such as colistin. Aim: To evaluate the use of colistin during 2017 in a university hospital, through the characterization of patients and treatment, associated microbiology, response to treatment and adverse effects. Methods: Retrospective observational design. The data of all patients who received colistin for at least 48 hours during the year 2017 were reviewed. Results: 55 patients were included, equivalent to 144 treatments. The respiratory focus was the main one (57.9%). 64% of the treatments began in the ICU, while 7% in the ward. Most of the patients has a recent hospitalization (86.8%) and has previous use of antibiotics (90.4%). The two main pathogens identified were Pseudomonas aeruginosa and Klebsiella spp. In 87.1% of the cases with microbiological justifications for the use of colistin, a favorable response was obtained. The average consumption of colistin was 2.4 DDD/100 beds/day. The department that consumed the most colistin was the ICU, with 45,5 DDD/100 beds/day, generally using a dose of 3 MIU every 8 hours IV and with low use of loading doses. Conclusion: Colistin corresponds to an antibiotic whose use is restricted to infections suspected or confirmed by multi-resistant bacterial agents. Its initial use in this serie was mainly empirical, in patients with risk factors for antibiotics resistance, it was used in association with other antimicrobials, being the respiratory the main infectious focus.

Unveiling the genome of a high-risk pandrug-resistant Klebsiella pneumoniae emerging in the Brazilian Amazon Region, 2022

BACKGROUND Pandrug-resistant (PDR) Klebsiella pneumoniae has been reported sporadically in many countries and remains rare in Brazil. OBJECTIVES This study unravelled the genetic determinants involved with the PDR background of a clinical ST11 K. pneumoniae recovered in the Brazilian Amazon Region, where K. pneumoniae genomic and epidemiological information is scarce. METHODS Kp196 was submitted to the antimicrobial susceptibility test by the disk-diffusion method and minimum inhibitory concentration (MIC) determination. The whole genome sequencing was obtained and the sequence type was determined by core genome multilocus sequence typing (cgMLST). Its intrinsic and acquired resistome was assessed by Comprehensive Antibiotic Resistance Database (CARD) and comparison with wild-type genes. FINDINGS The analyses revealed that Kp196 belonged to the pandemic ST11 and presented the PDR phenotype. Its acquired resistome was composed of a huge set of clinically relevant resistance determinants, including bla CTX-M-15 and bla NDM-1, all found in the vicinity of mobile platforms. Considering its intrinsic resistome, the multidrug resistance, especially to colistin, tigecycline and fluoroquinolones, was multifactorial and attributed to modifications (indels, missense mutations, and gene disruption) in several housekeeping genes (arnT/phoQ/mgrB/ramR/acrB/gyrA/parC/ompK35-36-37). The Kp196 intrinsic resistome was also observed in a ST11 environmental strain, although harbouring distinct acquired resistomes. CONCLUSIONS An accumulation of different resistance mechanisms regarding the intrinsic resistome accounts for a more stable resistome, strongly contributing to the Kp196 PDR phenotype.

Colistin resistance in Escherichia coli and Klebsiella pneumoniae in humans and backyard animals in Ecuador / Resistencia a la colistina de las bacterias Escherichia coli y Klebsiella pneumoniae en humanos y animales de granja en Ecuador / Resistência à colistina em Escherichia coli e Klebsiella pneumoniae em humanos e animais de quintal no Equador

ABSTRACT Objective. Colistin is an antibiotic of last resort for treating serious Gram-negative bacterial infections. However, the misuse of colistin, especially as an animal growth promoter, has contributed to increasing antimicrobial resistance, mediated mainly through plasmid transfer of the mcr-1 gene. This study assessed the prevalence of phenotypic and molecular colistin resistance in Escherichia coli and Klebsiella pneumoniae in Ecuador in healthy humans and their chickens and pigs. Methods. Fecal samples were collected from humans and their chickens and pigs in two rural coastal and Amazon regions between April and August 2020. Gram-negative bacteria were isolated and identified using conventional techniques. Phenotypic resistance was determined using the broth microdilution technique, and the mcr-1 gene was detected using conventional polymerase chain reaction. Results. A total of 438 fecal samples were obtained from 137 humans, 147 pigs and 154 chickens. The prevalence of E. coli isolates was 86.3% (378/438) and K. pneumoniae, 37.4% (164/438). Overall, the mcr-1 gene was found in 90% (340/378) of E. coli isolates, with higher prevalences found in isolates from coastal regions (96.5%, 191/198), humans (95.6%, 111/116) and chickens (91.8%, 123/134); for K. pneumoniae, the gene was found in 19.5% (32/164) of isolates, with equal distribution between regions and hosts. Only four isolates, two E. coli and two K. pneumoniae, showed phenotypic resistance: mcr-1 was present in both E. coli strains but absent in the K. pneumoniae strains. Conclusions. Despite a low prevalence of phenotypic resistance to colistin, the high prevalence of the mcr-1 gene in E. coli is of concern. Ecuador's ban on using colistin in animal husbandry must be enforced, and continual monitoring of the situation should be implemented.

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RESUMO Objetivo. A colistina é um antibiótico de último recurso para o tratamento de infecções graves por bactérias Gram-negativas. Entretanto, o uso indevido da colistina, principalmente como promotor de crescimento animal, tem contribuído para o aumento da resistência a antimicrobianos, principalmente por transferência horizontal do gene mcr-1 mediada por plasmídeos. Este estudo avaliou a prevalência de resistência fenotípica e molecular à colistina em Escherichia coli e Klebsiella pneumoniae no Equador em humanos hígidos e em galinhas e porcos por eles criados. Métodos. Entre abril e agosto de 2020, foram coletadas amostras de fezes de habitantes de duas regiões litorâneas e amazônicas do Equador e de galinhas e porcos por eles criados. Bactérias Gram-negativas foram isoladas e identificadas por meio de técnicas convencionais. A resistência fenotípica foi determinada pela técnica de microdiluição em caldo, e o gene mcr-1 foi detectado por reação em cadeia da polimerase convencional. Resultados. Foram obtidas 438 amostras fecais de 137 humanos, 147 suínos e 154 galinhas. A prevalência de isolados de E. coli foi de 86,3% (378/438), e de K. pneumoniae, 37,4% (164/438). Em geral, o gene mcr-1 foi encontrado em 90% (340/378) dos isolados de E. coli, com maiores prevalências encontradas em isolados de regiões litorâneas (96,5%, 191/198), humanos (95,6%, 111/116) e galinhas (91,8%, 123/134); para K. pneumoniae, o gene foi encontrado em 19,5% (32/164) dos isolados, com igual distribuição entre regiões e hospedeiros. Somente quatro isolados, dois de E. coli e dois de K. pneumoniae, demonstraram resistência fenotípica: o gene mcr-1 estava presente em ambas as cepas de E. coli, mas ausente nas de K. pneumoniae. Conclusões. Apesar da baixa prevalência de resistência fenotípica à colistina, a alta prevalência do gene mcr-1 em E. coli é preocupante. É preciso fiscalizar a proibição ao uso agropecuário de colistina no Equador e implementar o monitoramento contínuo da situação.

Effect of continuous renal replacement therapy on plasma concentration, clinical efficacy and safety of colistin sulfate / 中华危重病急救医学

Objective:To investigate the effects of continuous renal replacement therapy (CRRT) on plasma concentration, clinical efficacy and safety of colistin sulfate.Methods:Clinical data of patients received with colistin sulfate were retrospectively analyzed from our group's previous clinical registration study, which was a prospective, multicenter observation study on the efficacy and pharmacokinetic characteristics of colistin sulfate in patients with severe infection in intensive care unit (ICU). According to whether patients received blood purification treatment, they were divided into CRRT group and non-CRRT group. Baseline data (gender, age, whether complicated with diabetes, chronic nervous system disease, etc), general data (infection of pathogens and sites, steady-state trough concentration, steady-state peak concentration, clinical efficacy, 28-day all-cause mortality, etc) and adverse event (renal injury, nervous system, skin pigmentation, etc) were collected from the two groups.Results:A total of 90 patients were enrolled, including 22 patients in the CRRT group and 68 patients in the non-CRRT group. ① There was no significant difference in gender, age, basic diseases, liver function, infection of pathogens and sites, colistin sulfate dose between the two groups. Compared with the non-CRRT group, the acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) and sequential organ failure assessment (SOFA) were higher in the CRRT group [APACHE Ⅱ: 21.77±8.26 vs. 18.01±6.34, P < 0.05; SOFA: 8.5 (7.8, 11.0) vs. 6.0 (4.0, 9.0), P < 0.01], serum creatinine level was higher [μmol/L: 162.0 (119.5, 210.5) vs. 72.0 (52.0, 117.0), P < 0.01]. ② Plasma concentration: there was no significant difference in steady-state trough concentration between CRRT group and non-CRRT group (mg/L: 0.58±0.30 vs. 0.64±0.25, P = 0.328), nor was there significant difference in steady-state peak concentration (mg/L: 1.02±0.37 vs. 1.18±0.45, P = 0.133). ③ Clinical efficacy: there was no significant difference in clinical response rate between CRRT group and non-CRRT group [68.2% (15/22) vs. 80.9% (55/68), P = 0.213]. ④ Safety: acute kidney injury occurred in 2 patients (2.9%) in the non-CRRT group. No obvious neurological symptoms and skin pigmentation were found in the two groups. Conclusions:CRRT had little effect on the elimination of colistin sulfate. Routine blood concentration monitoring (TDM) is warranted in patients received with CRRT.

Randomized Control Study of Nebulized Colistin as an Adjunctive Therapy in Ventilator?Associated Pneumonia in Pediatric Postoperative Cardiac Surgical Population

Background:Ventilator?associated pneumonia (VAP) with multidrug?resistant (MDR) gram negative organisms is a common problem in intensive care unit (ICU). Aerosolized antibiotics enhance the efficacy of systemic antibiotics when added as adjuvants. Aim: The primary objective of the study was to compare the clinical and bacteriological outcome of patients with VAP who were administered intravenous (IV) antibiotics alone with those patients who were treated with adjunctive nebulized colistin (NC) along with IV antibiotics. The secondary objective was to study the occurrence of any adverse events during colistin nebulization. Settings and Design: The study was a prospective, randomized, double?blinded controlled study conducted at a tertiary?care teaching institution. Materials and Methods: Ninety?eight children from surgical ICU aged less than 12 years who were diagnosed with VAP due to gram negative bacteria following cardiac surgery were chosen and divided randomly into two groups. The experimental group (NC group) was treated with systemic antibiotics along with NC, whereas the control group (NS group) was administered systemic antibiotics with nebulized normal saline (NS). Clinical and bacteriological outcomes were noted. Statistical analysis was done using SPSS Version 20.0 software. The patient characteristics were compared using independent Student’s t test and Chi?square test. Results: There was a statistically significant reduction in the duration of mechanical ventilation, postoperative ICU and hospital stay (P < 0.05) in the NC group compared with the NS group. Conclusion: Aerosolized colistin may be considered as an adjunct to systemic IV antibiotics in pediatric patients with VAP due to gram negative bacteria susceptible to colistin.

Mechanisms involved in resistance to carbapenems among Acinetobacter baumannii isolates recovered in Brazil: A systematic review and meta-analysis

SUMMARY Introduction: Infections caused by carbapenem-resistant Acinetobacter baumannii (CRAB) is a health problem due to the limited therapeutic options available. This study was carried out to evaluate the main mechanisms of resistance of carbapenems in CRAB in the last 10 years in Brazil and to describe the susceptibility profile to tigecycline and polymyxins in these isolates. Material and methods: A systematic review was carried out according to Prisma in PUBMED/MEDLINE, Scopus, SciELO, Biblioteca Virtual de Saúde (BVS) and Cochrane Library. Data regarding enzyme resistance to carbapenems were evaluated by meta-analysis according to the random effect. Results: 21 articles were selected according to inclusion and exclusion criteria that evaluated 1096 CRAB. Most of the studies were carried out in the southern (33.3 %) and southeast (23.8 %) regions of Brazil (33.3 %) and in 2016 and 2018. According to the meta-analyzes, OXA-type carbapenemase was the main mechanism involved in the low susceptibility to carbapenems in CRAB (98%; 95% CI: 0.91, 0.99; I2 = 95%), with bla OXA-23-like (91 %; 95 % CI: 0.76; 0.97; I2 = 97 %) or bla OXA-51-like / ISAba1 (84 %; 95 % CI: 0.15, 0.99; I2 = 98 %) genes, followed by metallo-ß-lactamases (MBL) (12 %, 95 % CI: 0.09, 0.15, I2 = 99 %) and Klebsiella pneumoniae carbapenemase (KPC) (6 %, 95 % CI: 0.04; 0.08; I2 = 87 %). Conclusion: The included studies showed that susceptibility to colistin (99 %) and tigecy-cline (93 %) remains high and was not affected by carbapenem resistance.

Introducción: Las infecciones por Acinetobacter baumannii resistente a carbapenémicos (CRAB) es un problema de salud debido a las limitadas opciones terapéuticas disponibles. Este estudio se realizó para evaluar los principales mecanismos de resistencia de los carbapenémicos en CRAB en los últimos 10 años en Brasil y describir el perfil de susceptibilidad a tigeciclina y polimixinas en estos aislados. Material y métodos: Se realizó una revisión sistemática de acuerdo con Prisma en PUBMED/MEDLINE, Scopus, SciELO, Biblioteca Virtual de Saúde (BVS) y Cochrane Library. Los datos referentes a resistencia enzimática a los carbapenémicos se evaluaron mediante metaanálisis según el efecto aleatorio. Resultados: Se seleccionaron 21 artículos según criterios de inclusión y exclusión que evaluaron 1.096 CRAB. La mayoría de los estudios se llevaron a cabo en las regiones sur (33,3%) y sureste (23,8 %) de Brasil (33,3 %) y en los años 2016 y 2018. Según los metaanálisis, la carbapenemasa tipo OXA fue el principal mecanismo implicado en la baja susceptibilidad a los carbapenémicos en CRAB (98 %; IC 95 %: 0,91; 0,99; I² = 95 %), con bla OXA-23-like (91 %; 95 % CI: 0,76; 0,97; I² = 97 %) o bla OXA-51-like / ISAba1 (84 %; 95 % CI: 0,15; 0,99 ; I² = 98 %) genes, seguida de metalo-ß-lactamasas (MBL ) (12 %; IC95 %: 0,09; 0,15; I² = 99 %) y Klebsiella pneumoniae carbapenemase (KPC) (6 %; IC95 %: 0,04; 0,08; I² = 87 %). Conclusión: Los estudios incluidos mostraron que la susceptibilidad a la colistina (99 %) y tigeciclina (93 %) sigue siendo alta y no se ve afectada por la resistencia a los carbapenémicos.

Introdução: As infecções causadas por Acinetobacter baumannii resistente aos carbapenémicos (CRAB) são um problema de saúde devido às limitadas opções terapêuticas disponíveis. Este estudo foi realizado para avaliar os principais mecanismos de resistência aos carbapenêmicos em CRAB nos últimos 10 anos no Brasil e descrever o perfil de susceptibilidade à tigeciclina e às polimixinas nesses isolados. Material e métodos: Foi conduzida uma revisão sistemática segundo o Prisma nas bases de dados PUBMED/MEDLINE, Scopus, SciELO, Biblioteca Virtual de Saúde (BVS) e Biblioteca Cochrane. Os dados relativos à resistência enzimática aos carbapenêmicos foram avaliados por meta-análises de acordo com o efeito aleatório. Resultados: Foram selecionados 21 artigos de acordo com os critérios de inclusão e exclusão que avaliaram 1.096 CRAB. A maioria dos estudos foi realizada nas regiões Sul (33,3 %) e Sudeste (23,8 %) do Brasil e nos anos de 2016 e 2018. De acordo com as metanálises, a carbapenemase do tipo OXA foi o principal mecanismo envolvido na baixa susceptibilidade aos carbapenêmicos em CRAB (98 %; 95% IC: 0.91, 0.99; I² = 95 %), com bla OXA-23-like (91 %; 95 %; IC: 0,76; 0,97; I² = 97 %) ou bla OXA -51-like / ISAba1 (84 %; 95 % IC: 0.15, 0.99; I² = 98 %) genes, seguidos por metalo-ß-lactamases (MBL) (12 %, 95 % IC: 0,09, 0,15, I² = 99 %) e Klebsiella pneumoniae carbapenemase (KPC) (6 %, IC 95 %: 0,04; 0,08; I² = 87 %). Conclusão: Os estudos incluídos mostraram que a susceptibilidade à colistina (99 %) e tigeciclina (93 %) permanece alta e não foi afetada pela resistência aos carbapenêmicos.

An experimental study to evaluate the effect of polymixin E (Colistin) alone or in combination with gentamicin in McCarey-Kaufman corneal preservation medium on various drug resistant bacterial and fungal isolates

Purpose: To assess the efficacy of the addition of polymyxin E (colistin) in the McCarey-Kaufman (MK) corneal storage solution against multi-drug resistant strains of Enterobacteriaceae, Staphylococcus aureus, and Candida spp. Methods: A standard micro broth dilution test and a checkerboard assay were performed for five multi-drug resistant (MDR) clinical strains of P. aeruginosa and five clinical strains of methicillin-resistant S. aureus (MRSA) and C. albicans against colistin and gentamicin alone and in combination. The minimum inhibitory concentration (MIC) and the fractional inhibitory concentration index (FICI) were calculated to assess the efficacy of each combination. Results: The MIC of colistin was in the range of 1–2 ?g/mL for P. aeruginosa, whereas it was 256–1024 ?g/mL against S. aureus. In comparison, the MIC of gentamicin was found to be 0.5–512 ?g/mL and 0.5–8 ?g/mL against P. aeruginosa and S. aureus, respectively. All five isolates of C. albicans did not exhibit any susceptibility to either colistin or gentamicin even at a concentration of ? 512 ?g/ mL each. The checkerboard assay was performed to evaluate the nature of the interaction of the combination of colistin and gentamicin. Based on the FICI, it was observed that the colistin and gentamicin combination has a maximum synergistic effect (FIC <0.5) in 80% (4/5) for S. aureus isolates, whereas the maximum additive effect (FIC >0.5–4) was 100% (5/5) for P. aeruginosa and the minimum additive effect was 20% (1/5) for S. aureus isolates. Antagonism (FIC ? 4) was not observed in any combination between the strains used in the study. Both colistin and gentamicin alone or in combination were, however, ineffective against Candida spp. Conclusion: The addition of colistin has an inhibitory effect on bacterial contamination that could be possibly caused by MDR strains and could potentially be considered as an additional additive in corneal storage media.

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.

An LC-MS/MS method for simultaneous analysis of the cystic fibrosis therapeutic drugs colistin,ivacaftor and ciprofloxacin / 药物分析学报

Inhaled antibiotics such as colistin and ciprofloxacin are increasingly used to treat bacterial lung in-fections in cystic fibrosis patients.In this study,we established and validated a new HPLC-MS/MS method that could simultaneously detect drug concentrations of ciprofloxacin,colistin and ivacaftor in rat plasma,human epithelial cell lysate,cell culture medium,and drug transport media.An aliquot of 200 μL drug-containing rat plasma or cell culture medium was treated with 600 μL of extraction solution(acetonitrile containing 0.1％ formic acid and 0.2％ trifluoroacetic acid (TFA)).The addition of 0.2％ TFA helped to break the drug-protein bonds.Moreover,the addition of 0.1％ formic acid to the transport medium and cell lysate samples could significantly improve the response and reproducibility.After vortexing and centrifuging,the sample components were analyzed by HPLC-MS/MS.The multiple re-action monitoring mode was used to detect the following transitions:585.5-101.1 (colistin A),578.5-101.1 (colistin B),393.2-337.2 (ivacaftor),332.2-314.2 (ciprofloxacin),602.3-101.1 (polymyxin 81 as internal standard (IS)) and 595.4-101.1 (polymyxin B2 as IS).The running time of a single sample was only 6 min,making this a time-efficient method.Linear correlations were found for colistin A at 0.029-5.82 μg/mL.colistin B at 0.016-3.14 μg/mL.ivacaftor at 0.05-10.0 μg/mL,and ciprofloxacin at 0.043-8.58 μg/mL.Accuracy,precision,and stability of the method were within the acceptable range.This method would be highly useful for research on cytotoxicity,animal pharmacokinetics,and in vitro drug delivery.

Frecuencia de resistencia a la colistina en Pseudomonas aeruginosa: primer reporte en el Perú

El objetivo del estudio fue determinar la frecuencia de resistencia a la colistina en Pseudomonas aeruginosa provenientes de tres establecimientos de salud de Lima, criopreservados en el banco de cepas del Laboratorio de Resistencia a Antimicrobianos e Inmunopatología de la Universidad Peruana Cayetano Heredia (UPCH). El método de elución de discos de colistina en caldo fue empleado para la identificación fenotípica de la resistencia a la colistina; la detección de la expresión del gen mcr-1 se realizó mediante el método fenotípico de difusión de discos combinados de colistina y ácido etilendiaminotetraacético (EDTA) y la reacción en cadena de la polimerasa (PCR) para la identificación molecular del gen. De los 97 aislados estudiados, 7 (7,2%) fueron resistentes a la colistina y ninguno fue portador del gen mcr-1. Este estudio constituye el primer reporte en el Perú de aislados clínicos de Pseudomonas aeruginosa resistentes a la colistina, lo que implica la necesidad de implementar metodologías apropiadas para la vigilancia epidemiológica de patógenos resistentes a la colistina.

This study aimed to determine the frequency of colistin resistance in Pseudomonas aeruginosa isolates obtained from three healthcare facilities in Lima and cryopreserved at the Laboratorio de Resistencia Antimicrobianos e Inmunopatología of the Universidad Peruana Cayetano Heredia (UPCH). The colistin broth disk elution method was used for the phenotypic identification of colistin resistance. We detected the expression of the mcr-1 gene by using the phenotypic diffusion method with combined colistin and ethylenediaminetetraacetic acid (EDTA) disks; and polymerase chain reaction (PCR) was used for molecular identification of the gene. Of the 97 isolates, 7 (7.2%) were resistant to colistin; however, none carried the mcr-1 gene. This is the first report from Peru on clinical isolates of colistin-resistant Pseudomonas aeruginosa, which suggests the need for implementation of appropriate methodologies for the epidemiological surveillance of colistin-resistant pathogens.

Colistina en el tratamiento de infecciones por pseudomonas aeruginosa y acinetobacter baumannii extensivamente resistentes (XDR) en un hospital de tercer nivel / Colistin-based treatment for extensively drug resistant (XDR) Pseudomonas aeruginosa and Acinetobacter baumannii infection at a third level hospital

Resumen Objetivo: Describir la respuesta clínica y mortalidad general de Colistina en infecciones por Pseudomonas XDR y Acinetobacter XDR en el Hospital Nacional Arzobispo Loayza in Lima, Peru. Métodos: Estudio observacional, descriptivo y retrospectivo. Se incluyeron los registros de pacientes > 18 años, desde junio del 2014 a junio del 2016, que tuvieron infección por Pseudomonas XDR o Acinetobacter XDR confirmada por cultivo, y que recibieron colistina. Se realizó análisis univariado de las características generales de los pacientes; un análisis bivariado con test de Chi2 , t-student o ANOVA según corresponda, y además se describió los factores asociados a mortalidad. Resultados. Se incluyeron 56 registros de pacientes, la mediana de la edad fue 46,5 [31,5 a 63,5]. El 48,2% tuvo un cultivo positivo para Pseudomonas XDR y el 51,8% para Acinetobacter XDR. La respuesta clínica favorable fue 85,7% a los 15 días y de 78,6% a los 30 días. La mortalidad intrahospitalaria a los 30 días fue 21,4%, la mortalidad en UCI fue de 30,8% y la nefrotoxicidad fue de 5,4%. Conclusiones. Colistina combinada con otro antimicrobiano tuvo una respuesta clínica favorable en infección por Pseudomonas XDR o Acinetobacter XDR.

Abstract Objective: To describe the clinical response and overall mortality of Colistin in infections by Pseudomonas XDR and Acinetobacter XDR at the Hospital Nacional Arzobispo Loayza in Lima, Peru. Methods: Observational, descriptive, retrospective study. Records of all patients > 18 years old, from June 2014 to June 2016, who had infection by Pseudomonas XDR or Acinetobacter XDR confirmed by culture, and who received colistin, were included. A univariate analysis of the general characteristics of the patients was performed; a bivariate analysis with a Chi2, t-student or ANOVA test as appropriate, and the factors associated with mortality were also determined. Results: 56 patient records were included; the median age was 46,5 [31,5 to 63,5]. The Culture was positive for Pseudomonas XDR in 48,2% and for Acinetobacter XDR in 51,8%. The favorable clinical response was 85,7% at 15 days and 78,6% at 30 days. In-hospital mortality at 30 days was 21,4%, ICU mortality was 30,8% and nephrotoxicity was 5,4%. Conclusions: Colistin combined with another antimicrobial had a favorable clinical response in infection with Pseudomonas XDR and Acinetobacter XDR.

Resistencia a la colistina en cepas de Klebsiella pneumoniae multidrogorresistente del período 2015-2018 en un instituto materno perinatal de Lima, Perú / Colistin resistance in multidrug-resistant Klebsiella pneumoniae strains at a perinatal maternal institute in Lima, Peru, 2015-2018

RESUMEN El objetivo del estudio fue evaluar los niveles y mecanismos de resistencia a la colistina y a los carbapenémicos en cepas de Klebsiella pneumoniae multidrogorresistente aisladas durante el periodo 2015-2018 en el Instituto Materno Perinatal de Lima. Se analizó la sensibilidad mediante difusión en disco y microdilución. La presencia de genes de resistencia a los carbapenémicos y a la colistina se determinó por reacción en cadena de la polimerasa (PCR, por sus siglas en inglés) y se la relacionó con la clonalidad. Se analizaron 36 cepas de K. pneumoniae, cinco (13,8%) fueron resistentes a la colistina, pertenecían a diferentes grupos clonales. Se encontraron dos cepas con carbapenemasas (bla KPC y bla NDM) y no se detectaron genes plasmídicos para la colistina. Los niveles de resistencia al resto de antimicrobianos testados fueron elevados, a excepción de amikacina (13,9%). Los resultados destacan la presencia de cepas resistentes a la colistina (33,3% en 2018), situación preocupante por ser esta parte de las últimas alternativas de tratamiento para las infecciones causadas por patógenos multirresistentes.

ABSTRACT The objective of this study was to evaluate the presence of colistin- and carbapenemic-resistant genes in multidrug-resistant Klebsiella pneumoniae strains isolated at the Instituto Materno Perinatal de Lima (2015-2018). Susceptibility levels were analyzed by disk diffusion and microdilution. The presence of colistin- and carbapenemic-resistant genes was determined by polymerase chain reaction (PCR) and was related to clonality. A total of 36 K. pneumoniae strains were analyzed, 5 (13.8%) were resistant to colistin and belonged to different clonal groups. Only 2 strains were found with carbapenemases (bla KPC and bla NDM), and no colistin plasmid genes were detected. High resistance levels to the other tested antimicrobials were observed, except for amikacin (13.9%). The results highlight the presence of colistin-resistant strains (33.3% in 2018), a worrying situation as they are part of the latest treatment alternatives for infections caused by multiresistant pathogens.

Enterobacterales productores de betalactamasas de espectro extendido portadores del gen mcr-1 en Lima, Perú / Extended-spectrum beta-lactamase-producing enterobacterales carrying the mcr-1 gene in Lima, Peru

RESUMEN Se analizó la presencia del gen mcr-1 en 165 enterobacterales productores de betalactamasas de espectro extendido (EP-BLEE) recuperados en 2017 de sangre (40), orina (57), secreciones respiratorias bajas (12) e hisopados rectales (56) de pacientes hospitalizados en el Instituto Nacional de Enfermedades Neoplásicas (Perú). La identificación y la susceptibilidad antimicrobiana se determinaron por el sistema automatizado Phoenix M50; la resistencia a colistina por Colistin Agar-Spot (CAS); la detección de mrc-1 por el método fenotípico de predifusión de colistina e inhibición con EDTA (CPD-E) y por reacción en cadena de la polimerasa (PCR, por sus siglas en inglés). De los 165 EP-BLEE 25 fueron positivos para mcr-1 por el método CPD-E y se confirmó por PCR. Por el método CAS, 20/165 fueron resistentes a colistina. Además, mostraron resistencia a las fluoroquinolonas y a la gentamicina, y permanecieron sensibles a la amikacina; dos aislamientos presentaron metalocarbapenemasas. La obtención de datos sobre la resistencia a antimicrobianos considerados de última línea (colistina) es crucial para establecer medidas para su control.

ABSTRACT We analyzed the presence of the mcr-1 gene in 165 extended-spectrum beta-lactamase-producing enterobacterales (ESBL-PE) obtained during 2017, from blood (40), urine (57), lower respiratory secretions (12) and rectal swabs (56) of patients hospitalized in the Instituto Nacional de Enfermedades Neoplásicas (Peru). Antimicrobial identification and susceptibility were determined by the Phoenix M50 automated system; colistin resistance by Colistin Agar-Spot (CAS); mrc-1 detection by colistin pre-diffusion and inhibition with EDTA test (CPD-E) and by polymerase chain reaction (PCR). We found that from the 165 ESBL-PE, 25 were positive for mcr-1 by the CPD-E method and confirmed by PCR. Colistin resistance was found in 20/165 by using the CAS method. Additionally, they showed resistance to fluoroquinolones and gentamicin, while remaining sensitive to amikacin; two isolates presented metallo-carbapenemases. Obtaining data on resistance to last-line antimicrobials (colistin) is crucial to establish measures for its control.

Evaluación de la susceptibilidad a colistín y meropenem en Klebsiella pneumoniae productoras de carbapenemasas - KPC

The increase in infections caused by Enterobacterales resistant to carbapenems and other antimicrobials has limited the therapeutic alternatives which have led to the recovery of the use of colistin in clinical practices. Since 2015, a mechanism that confers resistance to colistin through plasmids related to the mcr-1 gene (Mobile Colistin Resistance) was detected, increasing the importance of its susceptibility test in the laboratory. Colistin susceptibility was evaluated by the disk elution method in 24 strains of Carbapenemase-producing type KPC Klebsiella pneumoniae, resulting 4 strains (17 %) resistant to colistin and 20 strains (83 %) intermediate. Also, in these strains, sensitivity to meropenem was evaluated by the E-test® method, finding that 10 strains (41,6 %) were within the acceptable range for their combination with colistin, 5 strains (20, 8 %) were within the uncertain range and 9 strains (37,4 %) were not appropriate for combination with colistin. For the combination of colistin with meropenem to be considered as a therapeutic alternative the MIC of colistin must be ≤ 2 µg /mL with meropenem ≤8 µg /mL, while the MIC between 12-16 µg/mL of meropenem may or not may work; and with a MIC of 32 µg/mL meropenem, the combination is not effective.

The prevalence of colistin-resistant Gram-negative bacteria isolated from hospitalized patients with bacteremia

This study sought to investigate the prevalence of colistin-resistant Gram-negative bacteria (CoR-GNB) amongPseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae isolated frompatients with bacteremia and to identify other antimicrobials as a potential therapy for CoR-GNB infections. Weretrospectively reviewed the data of non-repeated clinical bacterial isolates from patients admitted to PhramongkutklaoHospital during May 2017–April 2018. We obtained the minimum inhibitory concentrations (MICs) of the studiedisolates and interpreted the MIC values followed by the Clinical and Laboratory Standards Institute (CLSI) criteria. Outof 623 bacterial isolates, the prevalence of E. coli was predominantly high (349), followed by K. pneumoniae (150),P. aeruginosa (64), and A. baumannii (60). The CoR-GNB rates among E. coli, K. pneumoniae, A. baumannii, andP. aeruginosa were 2.9%, 17.3%, 5.0%, and 1.6%, respectively. Seven out of 26 colistin-resistant K. pneumoniaeisolates and seven out of 10 colistin-resistant E. coli isolates were still susceptible to carbapenems (the MICs forimipenem and meropenem were ≤1 µg/ml). Tigecycline and aminoglycosides might be the best therapeutic choicesagainst CoR-GNB. In conclusion, our findings confirmed a CoR-GNB prevalence of approximately 1.6%–17.3%,depending on the bacterial species. Certain available antimicrobials remain effective against CoR-GNB.

Impact of antibiotic stewardship program on usage of higher range of antibiotics in patients of intensive care units in a tertiary care hospital, India

Background: The aim of the study was to monitor the changes in antimicrobial use after implementation of Antibiotic Stewardship Programmed (ASP) and pattern of use of antimicrobials in the respective ICU抯.Methods: The study was conducted in three ICU抯 Adult ICU(AICU), Paediatric ICU (PICU), Neonatal ICU (NICU) -Six bedded each) over a period of six months from September 2018 to February 2019 in a tertiary care hospital. Antibiotics monitored over total 155 patients and antibiotics selected for the study are ?-lactam inhibitors, Carbapenem derivatives and ColistinResults: Out of total 155 patients 51% were males and the definitive therapy (Implementation of antibiotics according to the antibiotic policy of the hospital) in the respective ICU抯 showed increase from 66.7% to 83.3% after implementation of ASP activity in that particular duration. Antibiotic consumption showed fluctuation in the whole duration of the study (p value <0.05).Conclusions: Analysis of the study shows a positive impact on implementation of ASP programme in intensive care units, brought an effective increase in appropriate use of antimicrobials.

Evaluación de la elución de sensidiscos para la determinación de susceptibilidad a colistín en bacilos gramnegativos multi-resistentes / Evaluation of sensi-disk elution for colistin susceptibility determination in multidrug resistant gramnegative bacilli

Resumen Utilizando cepas clínicas de bacilos gramnegativos multi-resistentes (MDR), comparamos las CIM obtenidas de la microdilución en caldo, el método de referencia y el método de elución de sensidiscos. Encontramos que, con la excepción de A. baumannii, los resultados fueron muy similares. El método de elución de sensidiscos podría ser una buena alternativa y confiable para la determinación de la resistencia a colistín.

Abstract Using clinical strains of multidrug resistant (MDR) Gram negative bacilli, we compared MICs obtained from both broth microdilution, the reference method, and sensi-disk elution method. We found that, with A. baumannii exception, results were very similar. Sensi-disk elution method could be a good and reliable alternative for colistin resistance determination.