Susceptibilidad de enterobacterias a piperacilina/tazobactam en un hospital pediátrico de Chile / Enterobacteriaceae susceptibility to piperacillin/tazobactam in a Chilean pediatric hospital

Resumen Introducción: Las enterobacterias son bacilos gram-negativos responsables de infecciones graves en el ser humano. Se reporta una susceptibilidad en Klebsiella pneumoniae de 79,4% a piperacilina/tazobactam (PIP/TAZO) en hospitales pediátricos de Chile, pero según nuestro conocimiento, no existen datos publicados a la fecha respecto a la susceptibilidad de otras enterobacterias a PIP/TAZO en la población pediátrica chilena. Objetivo: Determinar la susceptibilidad in vitro a PIP/TAZO en cepas obtenidas de infecciones por Enterobacteriaceae en un hospital pediátrico de Chile. Material y Método: Estudio descriptivo y prospectivo de cepas de Enterobacteriaceae en Hospital de Niños Roberto del Río (HRRIO) entre 1 de enero de 2013 y el 27 de agosto de 2014. Se definió la susceptibilidad a PIP/TAZO por método de gradiente (E-test®) según puntos de corte CLSI 2014. Resultados: Se incluyeron 163 casos. El promedio de edad fue de 4 años 15 días. 70,6% de sexo femenino. El 79,7% de las cepas fueron aisladas en urocultivos. La susceptibilidad de Enterobacteriaceae a PIP/TAZO fue 95,1% (n = 155). La susceptibilidad intermedia fue 1,8% (n = 3). Discusión: Los aislados estudiados presentan alta susceptibilidad a PIP/TAZO. Este hallazgo puede explicarse por la baja circulación de microrganismos productores de BLEE y el limitado uso de PIP/TAZO en esta población pediátrica.

Introduction: Enterobacteriaceae are a group of gram-negative rods that can cause serious infections in humans. A susceptibility in Klebsiella pneumoniae of 79.4% to piperacillin/tazobactam (PIP/TAZO) is reported in pediatric hospitals in Chile. There is no published data published to date regarding PIP/TAZO susceptibility to other Enterobacteriaceae species in this population. Aim: To measure the in vitro PIP/TAZO susceptibility in Enterobacteriaceae isolates from patients in a pediatric hospital in Chile. Methods: Descriptive and prospective study of Enterobacteriaceae positive cultures from patients assisting to the "Hospital de niños Roberto del Río" (HRRIO) between January 2013 and August 2014. PIP/TAZO susceptibility was established by gradient diffusion method (E-test®) according to the 2014 CLSI standards. Results: 163 cases were included. The average age was 4 years and 15 days. 70.6% were female. 79.7% of samples were urine cultures. PIP/TAZO susceptibility in Enterobacteriaceae was 95.1% (n = 155). The intermediate susceptibility was 1.8% (n = 3). Discussion: The isolates studied present high susceptibility to PIP/TAZO. This finding could be explained by the fact that this population has not been exposed to this antimicrobial therapy and also the low rates for ESBL in pediatric infections.

Ceftolozane-tazobactam activity against drug-resistant Enterobacteriaceae and Pseudomonas aeruginosa causing healthcare-associated infections in Latin America: report from an antimicrobial surveillance program (2013-2015)

ABSTRACT This study evaluated the in vitro activity of ceftolozane-tazobactam and comparator agents tested against Latin American isolates of Enterobacteriaceae and Pseudomonas aeruginosa from patients with health care-associated infections. Ceftolozane-tazobactam is an antipseudomonal cephalosporin combined with a well-established β-lactamase inhibitor.A total of 2415 Gram-negative organisms (537 P. aeruginosa and 1878 Enterobacteriaceae) were consecutively collected in 12 medical centers located in four Latin American countries. The organisms were tested for susceptibility by broth microdilution methods as described by the CLSI M07-A10 document and the results interpreted according to EUCAST and CLSI breakpoint criteria. Results: Ceftolozane-tazobactam (MIC50/90, 0.25/32 µg/mL; 84.2% susceptible) and meropenem (MIC50/90, ≤0.06/0.12 µg/mL; 92.6% susceptible) were the most active compounds tested against Enterobacteriaceae. Among the Enterobacteriaceae isolates tested, 6.6% were carbapenem-resistant Enterobacteriaceae and 26.4% exhibited an extended-spectrum β-lactamase non-carbapenem-resistant phenotype. Whereas ceftolozane-tazobactam showed good activity against extended-spectrum beta-lactamase, non-carbapenem-resistant phenotype strains of Enterobacteriaceae (MIC50/90, 0.5/>32 µg/mL), it lacked useful activity against strains with a (MIC50/90, >32/>32 µg/mL; 1.6% S) carbapenem-resistant phenotype. Ceftolozane-tazobactam was the most potent (MIC50//90, 0.5/16 µg/mL) β-lactam agent tested against P. aeruginosa isolates, inhibiting 86.8% at an MIC of ≤4 µg/mL. P. aeruginosa exhibited high rates of resistance to cefepime (16.0%), ceftazidime (23.6%), meropenem (28.3%), and piperacillin-tazobactam (16.4%). Conclusions: Ceftolozane-tazobactam was the most active β-lactam agent tested against P. aeruginosa and demonstrated higher in vitro activity than available cephalosporins and piperacillin-tazobactam when tested against Enterobacteriaceae.

Pharmacodynamic profiling of commonly prescribed antimicrobial drugs against Escherichia coli isolates from urinary tract

Since antimicrobial resistance among uropathogens against current first line agents has affected the management of severe urinary tract infection, we determined the likelihood that antibiotic regimens achieve bactericidal pharmacodynamic exposures using Monte Carlo simulation for five antimicrobials (ciprofloxacin, ceftriaxone, piperacillin/tazobactam, ertapenem, and meropenem) commonly prescribed as initial empirical treatment of inpatients with severe community acquired urinary tract infections. Minimum inhibitory concentration determination by Etest was performed for 205 Brazilian community urinary tract infection Escherichia coli strains from 2008 to 2012 and 74 E. coli bloodstream strains recovered from a surveillance study. Pharmacodynamic exposure was modeled via a 5000 subject Monte Carlo simulation. All isolates were susceptible to ertapenem and meropenem. Piperacillin/tazobactam, ceftriaxone and ciprofloxacin showed 100%, 97.5% and 83.3% susceptibility among outpatient isolates and 98.6%, 75.7% and 64.3% among inpatient isolates, respectively. Against outpatient isolates, all drugs except ciprofloxacin (82.7% in aggressive and 77.6% in conservative scenarios) achieved high cumulative fraction of response: car-bapenems and piperacillin/tazobactam cumulative fraction of responses were close to 100%, and ceftriaxone cumulative fraction of response was 97.5%. Similar results were observed against inpatients isolates for carbapenems (100%) and piperacillin/tazobactam (98.4%), whereas ceftriaxone achieved only 76.9% bactericidal cumulative fraction of response and ciprofloxacin 61.9% (aggressive scenario) and 56.7% (conservative scenario) respectively. Based on this model, standard doses of beta-lactams were predicted to deliver sufficient pharmacodynamic exposure for outpatients. However, ceftriaxone should be avoided for inpatients and ciprofloxacin empirical prescription should be avoided in both inpatients and outpatients with complicated urinary tract infection.

Comparison of in vitro activities of ceftazidime, piperacillin-tazobactam, and cefoperazone-sulbactam, and the implication on empirical therapy in patients with cancer.

Background: Infection is a common cause of morbidity and mortality in cancer patients. In most of these cases empirical treatment is provided because the focus of infection is not identified. Empiric antibiotics provided to these patients are based on isolates, sensitivity, and on guidelines. Here we have compared three antibiotics recommended as empirical treatment by the Infectious Disease Society of America (IDSA). Aims: To compare the three antibiotic sensitivities for gram negative isolates at our institute. Objective: To choose the optimal antibiotic as the empirical treatment for cancer patients developing infections. Materials and Methods: We collected the data on isolates and antibiotic sensitivity patterns of isolates for ceftazidime, piperacillin + tazobactum, and cefoperazone from the medical oncology department. We subsequently compared the sensitivity of these three antibiotics. Statistical Methods: The isolates were mapped using the WHONET 5.4 software. The analysis was conducted using SPSS 15.0 for Windows. McNemar Chi-square test was used to compare the sensitivity percentages between any two antibiotics. The agreement between the antibiotic and the gold standard was calculated using the Kappa statistic. Two tailed p values were reported. Results: The results showed that there was a difference among sensitivities for these antibiotics. It appears that the sensitivity of ceftazidime was inferior to the two other antibiotics. Also cefoperazone has better sensitivity as compared to piperacillin + tazobactum. Conclusion: In spite of these three antibiotics being recommended by IDSA our data suggest that it should not be followed blindly and local sensitivity data is important for formulating institutional guidelines for using antibiotics.

Control of multi-resistant bacteria and ventilator-associated pneumonia: is it possible with changes in antibiotics?

Potent antimicrobial agents have been developed as a response to the development of antibiotic-resistant bacteria, which especially affect patients with prolonged hospitalization in Intensive Care Units (ICU) and who had been previously treated with antimicrobials, especially third-generation cephalosporins.This study was to determine how changes in the empirical treatment of infections in ICU patients affect the incidence of Gram-negative bacteria species and their susceptibility to antimicrobials, and examine the impact of these changes on nosocomial infections. A prospective interventional study was performed in a university hospital during two periods: 1) First period (September 1999 to February 2000); and 2) Second period (August 2000 to December 2000); empirical treatment was changed from ceftriaxone and/or ceftazidime in the first period to piperacillin/tazobactam in the second. ICU epidemiological and infection control rates, as well as bacterial isolates from upper airways were analyzed. Ceftazidime consumption dropped from 34.83 to 0.85 DDD/1000 patients per day (p=0.004). Piperacillin/tazobactam was originally not available; its consumption reached 157.07 DDD/1000 patients per day in the second period (p=0.0002). Eighty-seven patients and 66 patients were evaluated for upper airway colonization in the first and second periods, respectively. There was a significant decrease in the incidence of K. pneumoniae (p=0.004) and P. mirabilis (p=0.036), restoration of K. pneumoniae susceptibility to cephalosporins (p<0.0001) and reduction of ventilator-associated pneumonia rates (p<0.0001). However, there was an increase in P. aeruginosa incidence (p=0.005) and increases in ceftazidime (p=0.003) and meropenem (p<0.0001) susceptibilities. Changing antimicrobial selective pressure on multi-resistant Gram-negative bacteria helps control ventilator-associated pneumonia and decreases antimicrobial resistance.

Unique metabolic properties of Mycobacterium leprae.

My first contact with Dr. Dharmendra was through correspondence. While working for Ph.D., I wrote to him that a section in his book "Notes on Leprosy" was ambiguous. Instead of ignoring the letter, he replied, agreeing to clarify it in the revised edition. I went to work at Carville at the invitation of Dr. Kirchheimer, who had seen my Ph.D. thesis. Dr. Dharmendra visited Carville to receive the Damien-Dutton award and stayed there for a few days. Carville is an isolated place with no public transportation. I used to take him for afternoon drives to the countryside around Carville. He published some of our papers in Leprosy in India and later in Indian Journal of Leprosy. He was very prompt in acknowledging receipt of manuscripts and suggesting any changes to be made. He also reprinted in the Journal several of our papers published elsewhere, and also a lecture I gave at a meeting of the Japanese Leprosy Association. During one of my visits to India, Dr. M. C. Vaidya had arranged a talk by me at the All India Institute of Medical Sciences, New Delhi. At the invitation of Dr. Dharmendra, I visited him in his home. We used to exchange new year cards and letters. He wrote to me about his eye infection and consequent loss of sight in one eye. He asked me to write an editorial for an issue of Indian Journal of Leprosy (January 1989). The last time I met him was during the International Leprosy Congress held in New Delhi.

Inibidores das beta-lactamases e seu uso clínico / Beta-lactamase inhibitors and its clinical use

Os autores fazem uma revisäo bibliográfica sobre as drogas inibidoras das beta-lactamases e abordam sua farmacologia e seu uso clínico atual, baseando-se na combinaçäo dos antimicrobianos e no próprio inibidor da beta-lacatamse. Há muito tempo é conhecido o fato de que germes gram positivos e germes gran negativos säo capazes de produzir enzimas de composiçäo química complexa denominadas beta-lactamases, as quais têm a propriedade de atuar sobre o anel beta-lactamases, beta-lactâmico (componente da estrutura química de alguns antimicrobianos) inativando-o e fazendo com que tais germes se tornem resistentes a estes antimicrobianos (3). Investigaçöes clínicas recentes levaram a descoberta de certas moléculas que podem se ligar de forma irreversível as beta-lactamases e inativá-las, impedindo assim a destruiçäo dos antimicrobianos beta-lactâmicos (3), fazendo com que drogas antigas como ampicilina, amoxacilina e ticarcilina passem a atuar, quando associadas a estas novas substâncias, sobre germes produtores de beta-lactamases, propiciando ao paciente ao mesmo tempo o acesso a uma terapia de custo menor e de menor toxicidade intrínseca. Os agentes inibidores das beta-lactamases têm propriedades, consideravelmente diferentes daquelas das penicilinas e cefalosporinas, assim como säo estruturalmente diferentes destas, tendo baixa atividade intrínseca sobre micoorganismos (4) quando isolados mas que acreditamos de grande valor terapêutico no futuro. Atualmente säo conhecidos dois agentes inibidores das beta-lactamases: o ácido clavulcânico e o sulbactam, os quais passaremos a abordar (5)