Resistencia a fármacos antituberculosos en Cuba, 2015-2017 / Resistance to tuberculosis drugs in Cuba, 2015-2017

Introducción: La tuberculosis persiste como un importante problema de salud mundial. En el 2016 se estimaron 600 000 casos de resistente a rifampicina, y entre estos 490 000 casos multidrogorresistentes. Objetivo: Describir el comportamiento de la resistencia de los aislados de M. tuberculosis de pacientes con tuberculosis pulmonar notificados en Cuba entre los años 2015-2017. Métodos: Se determinó la susceptibilidad a isoniacida y rifampicina mediante el método de la nitratasa. A los aislados resistentes a rifampicina/multidrogorresistentes se les determinó mediante el método proporcional la susceptibilidad a ofloxacina, kanamicina, amikacina y capreomicina. Resultados: El 93,2 por ciento de los aislados fueron sensibles a isoniacida y rifampicina. En 39 se identificó resistencia a isoniacida y 23 fueron resistente a rifampicina. Se identificaron 10 multidrogorresistentes. No se detectó resistencia a fármacos de segunda línea. Conclusiones: Los resultados alertan sobre la necesidad de investigar las causas que han conllevado al incremento de la tuberculosis resistente en Cuba(AU)

Introduction: Tuberculosis continues to be an important health problem worldwide. In the year 2016, as many as 600 000 cases of rifampicin resistance were estimated, among which 490 000 were multi-drug resistant. Objective: Describe the behavior of resistance to M. tuberculosis isolates in patients with pulmonary tuberculosis reported in Cuba in the period 2015-2017. Methods: Susceptibility to isoniazid and rifampicin was determined by the nitratase method. Susceptibility of rifampicin resistant / multi-drug resistant isolates to ofloxacin, kanamycin, amikacin and capreomycin was determined by the proportional method. Results: Of the isolates analyzed, 93.2 percent were sensitive to isoniazid and rifampicin. Isoniazid resistance was identified in 39 and 23 were rifampicin resistant. Ten multi-drug resistant isolates were identified. Resistance to second line drugs was not detected. Conclusions: Results warn about the need to study the factors leading to the increase in resistant tuberculosis in Cuba(AU)

Patrones de resistencia a los antimicrobianos en serovares de Salmonella enterica en Perú, 2012-2015 / Patterns of resistance to antimicrobials in serovars of Salmonella enterica in Peru, 2012-2015

Resumen Introducción: La salmonelosis es una zoonosis universal, causante de frecuentes brotes de enfermedades transmitidas por alimentos; Salmonella enterica es la especie con la mayor prevalencia, describiéndose un aumento progresivo de su resistencia a antimicrobianos. Objetivo: Determinar la frecuencia de serotipos y los patrones de resistencia antimicrobiana en aislados de S. enterica remitidos al Instituto Nacional de Salud, Lima, Perú. Materiales y Métodos: Se realizó un estudio descriptivo, transversal. Se incluyeron en el estudio todas las cepas remitidas como parte de la vigilancia nacional basada en laboratorio entre los años 2012 y 2015. Las cepas fueron confirmadas mediante pruebas convencionales y serotipificadas por el esquema de Kauffmann-White; la susceptibilidad antimicrobiana y la confirmación del fenotipo BLEE se realizó según el método de Kirby-Bauer y método de Jarlier. Resultados: Un total de 540 cepas de S. enterica fueron incluidos en el estudio, de las que 96% (520/540) correspondió a cepas de origen humano y 4% (20/540) de origen no humano (aves, alimentos y ambiental). En muestras humanas, el serovar más frecuente fue S. Infantis (57%), seguido de S. Enteritidis (27%) y S. Typhimurium (6%). Se encontró una alta resistencia a nitrofurantoína (74%), ácido nalidíxico (64%), ciprofloxacina (63%), tetraciclina (63%), ampicilina (56%), cotrimoxazol (56%), cefotaxima (53%) y cloranfenicol (50%). En muestras no humanas, el serotipo más frecuente fue S. Infantis (45%), seguido de S. Typhimurium (40%) y S. Enteritidis (10%). encontrándose una alta resistencia a ciprofloxacina (45%), cotrimoxazol (40%), y tetraciclina (40%). El 65% del total de las cepas presentó resistencia a más de dos antimicrobianos, 43,3% fueron productoras de BLEE y 99% de éstas presentaron resistencia a entre seis y ocho antimicrobianos. Conclusiones: Se encontró una alta frecuencia de Salmonella Infantis productoras de BLEE, con multi-resistencia a los antimicrobianos en los aislados de muestras humanas y no humanas recibidas en el Instituto Nacional de Salud.

Abstract Background: Salmonellosis is a universal zoonosis, causing frequent outbreaks of foodborne illness; Salmonella enterica is the species with the highest prevalence, a progressive increase in its resistance to antimicrobials is described. Aim: To determine the frequency of serovars and antimicrobial resistance patterns in S. enterica isolates submitted to the National Institute of Health, Lima, Peru. Methods: This is a cross-sectional study. All strains referred as part of national laboratory-based surveillance between 2012 and 2015 were included in the study. Strains were confirmed by conventional tests and serotyped by the Kauffmann-White scheme; antimicrobial susceptibility and confirmation of the BLEE phenotype was performed according to the method of Kirby-Bauer and Jarlier's method. Results: A total of 540 strains of S. enterica were included in the study, where 96% (520/540) corresponded to human strains and 4% (20/540) to non-human strains (birds, food and environmental). In human samples, the most frequent serovar was S. Infantis (57%), followed by S. Enteritidis (27%) and S. Typhimurium (6%). High resistance to nitrofurantoin (74%), nalidixic acid (64%), ciprofloxacin (63%), tetracycline (63%), ampicillin (56%), sulfamethoxazole-trimethoprim (56%), cefotaxime (53%) and chloramphenicol (50%) was detected. In non-human samples, the most frequent serotype was S. Infantis (45%), followed by S. Typhimurium (40%) and S. Enteritidis (10%); a high resistance to nalidixic acid (55%), ciprofloxacin (45%), sulfamethoxazole-trimethoprim (40%), nitrofurantoin (40%), tetracycline (40%) was found. 65% of all strains had resistance to more than two antibiotics, 43,3% were ESBL producers and 99% of these had resistance between six and eight antibiotics. Conclusions: We found a high frequency of S. Infantis producing ESBL with multi-resistance to the antimicrobials in human and nonhuman samples received by the National Institute of Health.

Evaluation of in vitro activity of ceftolozane-tazobactam against recent clinical bacterial isolates from Brazil - the EM200 study

ABSTRACT Background: The emergence of antibiotic resistance is increasing and there are few effective antibiotics to treat infections caused by resistant and multidrug resistant bacterial pathogens. This study aimed to evaluate the in vitro activity of ceftolozane-tazobactam against clinical bacterial isolates from Brazil. Methods: A total of 673 Gram-negative bacterial isolates including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and other Enterobacterales collected from 2016 to 2017 were tested, most of them isolated from patients in intensive care units. Minimum inhibitory concentrations (MIC50/90) were determined by broth microdilution for amikacin, aztreonam, cefepime, cefotaxime, cefoxitin, ceftolozane-tazobactam, ceftazidime, ceftriaxone, ciprofloxacin, colistin, ertapenem, imipenem, levofloxacin, meropenem, and piperacillin-tazobactam using dried panels. Antimicrobial susceptibility results were interpreted according to Clinical and Laboratory Standards Institute criteria. Results: Susceptibility rates to ceftolozane-tazobactam ranged from 40.4% to 94.9%. P. aeruginosa susceptibility rate to ceftolozane-tazobactam was 84.9% (MIC50/90, 1/16 µg/mL) and 99.2% to colistin. For E. coli, ceftolozane-tazobactam inhibited 94.9% (MIC50/90, 0.25/1 µg/mL) of the microorganisms. The susceptibility rate of K. pneumoniae to ceftolozane-tazobactam was 40.4% (MIC50/90, 16/>32 µg/mL). Other Enterobacterales have shown susceptibility rates of 81.1% (MIC50/90, 0.5/16 µg/mL) to ceftolozane-tazobactam, 93.9% to meropenem, 90.9% to amikacin (90.9%), and 88.6% to ertapenem. In non-carbapenemase producing isolates, AmpC mutations were found three isolates. Conclusions: Ceftolozane-tazobactam has shown relevant activity against a large variety of the analyzed microorganisms collected from multiple centers in Brazil, showing promising results even in multidrug resistant strains.

Genomic analysis of Latin American-Mediterranean family of Mycobacterium tuberculosis clinical strains from Kazakhstan

The human-adapted strains of the Mycobacterium tuberculosis complex (MTBC) comprise seven phylogenetic lineages originally associated with their geographical distribution. Here, we report the genomes of three drug-resistant clinical isolates of the Latin American-Mediterranean (LAM) family collected in Kazakhstan. We utilised whole-genome sequencing to study the distribution and drug resistance of these isolates. Phylogenetic analysis grouped the genomes described in this study with the sequences from Russia, Uzbekistan, and Kazakhstan belonging to the LAM family. One isolate has acquired extensive drug resistance to seven antituberculosis drugs. Our results suggest at least two multi-drug resistant (MDR)/extensively drug-resistant (XDR)-associated genotypes of the LAM family circulate in Kazakhstan.

Evaluation of drug susceptibility profile of Mycobacterium tuberculosis Lineage 1 from Brazil based on whole genome sequencing and phenotypic methods

BACKGROUND The evaluation of procedures for drug susceptibility prediction of Mycobacterium tuberculosis based on genomic data against the conventional reference method test based on culture is realistic considering the scenario of growing number of tools proposals based on whole-genome sequences (WGS). OBJECTIVES This study aimed to evaluate drug susceptibility testing (DST) outcome based on WGS tools and the phenotypic methods performed on isolates of M. tuberculosis Lineage 1 from the state of Pará, Brazil, generally associated with low levels of drug resistance. METHODOLOGY Culture based DST was performed using the Proportion Method in Löwenstein-Jensen medium on 71 isolates that had been submitted to WGS. We analysed the seven main genome sequence-based tools for resistance and lineage prediction applied to M. tuberculosis and for comparison evaluation we have used the Kappa concordance test. FINDINGS When comparing the WGS-based tools against the DST, we observed the highest level of agreement using TB-profiler. Among the tools, TB-profiler, KvarQ and Mykrobe were those which identified the largest number of TB-MDR cases. Comparing the four most sensitive tools regarding resistance prediction, agreement was observed for 43 genomes. MAIN CONCLUSIONS Drug resistance profiling using next-generation sequencing offers rapid assessment of resistance-associated mutations, therefore facilitating rapid access to effective treatment.

Evaluación de la sensibilidad de cepas de Pseudomonas aeruginosa multi-resistentes frente a ceftolozano/tazobactam / Evaluation of susceptibility of multidrug-resistant Pseudomonas aeruginosa strains against ceftolozane/tazobactam

Resumen Introducción: Pseudomonas aeruginosa es un patógeno oportunista asociado a alta morbi-mortalidad. Para cepas multi-resistentes (MDR), ceftolozano/tazobactam (CTZ) se ha autorizado por la Agencia Europea del Medicamento (EMA) para infecciones del tracto urinario complicadas, pielonefritis aguda e infecciones intra-abdominales complicadas. Objetivo: Determinar la sensibilidad a CTZ de P. aeruginosa MDR en muestras clínicas aisladas en el Hospital Universitario Puerto Real. Material y Métodos: Se estudió la sensibilidad según criterios EUCAST a CTZ de cepas de P. aeruginosa MDR, entre enero de 2015 y agosto de 2017. Los criterios de multi-resistencia fueron definidos por el Centers for Disease Control and Prevention. La sensibilidad antimicrobiana se obtuvo mediante sistema MicroScan® (Beckman Coulter). La sensibilidad a CTZ se determinó mediante tiras de gradiente (Liofilchem®, Werfen). Resultados: De 1253 cepas, 7% fueron MDR. Se estudió la sensibilidad de 78 cepas de P. aeruginosa MDR, de las cuales cinco (6,4%) resultaron resistentes a CTZ según criterios EUCAST. Conclusiones: En nuestro medio la resistencia in vitro a CTZ en cepas de P. aeruginosa MDR es aproximadamente 6%; CTZ es una opción de tratamiento de infecciones por cepas de P. aeruginosa MDR cuando no exista otra alternativa y se haya comprobado su sensibilidad in vitro.

Background: Pseudomonas aeruginosa is an opportunistic pathogen associated with high morbidity and mortality. For multidrug-resistant strains (MDR), ceftolozane/tazobactam (CTZ) has been authorized by the European Medicines Agency (EMA) for complicated urinary tract infections, acute pyelonephritis, and complicated intraabdominal infections. Aim: To determine the susceptibility to CTZ of P. aeruginosa MDR in isolated clinical samples at the University Hospital Puerto Real. Methods: The susceptibility according to the EUCAST to CTZ criteria of strains of P. aeruginosa MDR, between January 2015 and August 2017 has been studied. The multiresistance criteria were those defined by the Centers for Disease Control and Prevention. The antibiotic susceptibility was obtained by automated MicroScan® system (Beckman Coulter). Susceptibility to CTZ was determined using gradient strips (Liofilchem®, Werfen). Results: Of 1253 strains isolated, 7% presented MDR. We studied the susceptibility of a total of 78 strains of MDR P. aeruginosa, of which 5 (6.4%) were resistant to CTZ according to the EUCAST criteria. Conclusions: In our environment, the in vitro resistance to CTZ in MDR P. aeruginosa strains is approximately 6%. CTZ is an option for the treatment of infections by MDR P. aeruginosa when there is no other alternative and its in-vitro susceptibility has been proven.

Staphylococcus aureus in tonsils of patients with recurrent tonsillitis: prevalence, susceptibility profile, and genotypic characterization

ABSTRACT Introduction: Bacterial tonsillitis is an upper respiratory tract infection that occurs primarily in children and adolescents. Staphylococcus aureus is one of the most frequent pathogens in the etiology of tonsillitis and its relevance is due to its antimicrobial resistance and persistence in the internal tissues of the tonsils. Tonsillectomy is indicated in cases of recurrent tonsillitis after several failures of antibiotic therapy. Material and methods: In this study we evaluated 123 surgically removed tonsils from patients who had history of recurrent tonsillitis. The tonsils were submitted to microbiological analysis for detection of S. aureus. The isolates were identified by PCR for femA gene. Antimicrobial susceptibility of the isolates was determined by disk diffusion tests. All isolates were submitted to PCR to detect mecA and Panton-Valentine leucocidin (PVL) genes. The genetic similarity among all isolates was determined by pulsed field gel electrophoresis. Results: Sixty-one S. aureus isolates were obtained from 50 patients (40.7%) with mean age of 11.7 years. The isolates showed high level resistance to penicillin (83.6%), 9.8% had inducible MLSb phenotype, and 18.0% were considered multidrug resistant (MDR). mecA gene was detected in two isolates and the gene coding for PVL was identified in one isolate. The genetic similarity analysis showed high diversity among the isolates. More than one genetically different isolate was identified from the same patient, and identical isolates were obtained from different patients. Conclusions: MDR isolates colonizing tonsils even without infection, demonstrate persistence of the bacterium and possibility of antimicrobial resistance dissemination and recurrence of infection. A specific clone in patients colonized by S. aureus was not demonstrated.

Temporal evolution of antimicrobial resistance among Neisseria gonorrhoeae clinical isolates in the most populated South American Metropolitan Region

A total of 124 Neisseria gonorrhoeae isolates recovered during a 12-year period (2003-2015) from outpatients assisted at Centro de Referência e Treinamento DST/AIDS-CRT of São Paulo city, Brazil, were analysed. The following resistance rates were observed: penicillin-59.6%, ciprofloxacin-15.3%, and azithromycin-6.7%. Although reduced susceptibility to these drugs was observed since 2003, no ceftriaxone-resistant isolates were detected. Ciprofloxacin- and azithromycin non-susceptible isolates were grouped in 11 clusters. Mutations were detected in GyrA and ParC of isolates 124 and 260, and a C2611T substitution on 23S rRNA alleles was also observed in isolate 260. Both isolates belonged to ST1901/ST6210 (MSLT/NG-MAST schemes).

Bacteriemia por Pseudomonas aeruginosa (PAE) en niños / Pseudomonas aeruginosa-associated bacteremia en children

Introducción. La bacteriemia por Pseudomonas aeruginosa (PAE) en niños es infrecuente. Objetivo.Describir las características epidemiológicas, clínicas, microbiológicas y evolutivas en niños con bacteriemia por PAE. Métodos. Estudio de cohorte retrospectivo. Resultados. Se incluyeron 100 pacientes (p). La mediana de edad fue de 27 meses (RIC 6-88).Tenían enfermedad de base: 93 p (93%) y 36 de ellos estaban neutropénicos. Ochenta y cinco p (85%) habían recibido antibióticos en el último mes, 60 (60%) tuvieron procedimientos invasivos previos y 81 (81%) tuvieron internaciones previas. Ingresaron con shock séptico 42 p (42%), 56 p (56%) fueron admitidos en unidad de cuidados intensivos (UCI) y 49 (49%) requirieron ventilación mecánica (VM). La bacteriemia fue primaria en 17 p (17%); asociada a catéter en 15 p (15%) y secundaria en 68 p (68%). El foco más frecuente fue mucocutáneo, 21 p, seguido por el pulmonar, 20 p. El tratamiento empírico fue adecuado en 84 p (84%). La resistencia a uno o más grupos de antibióticos se dio en el 38% de los casos, 11% fueron multirresistentes y 15% fueron resistentes sólo a carbapenemes. Fallecieron 31 p (31%). Pseudomonas aeruginosa resistente a carbapenemes en forma exclusiva o combinada con otros antibióticos se relacionó en esta serie a exposición previa a antibióticos, (p≤0,03), tratamiento empírico inicial inadecuado (p≤0,006) y mayor mortalidad (p≤0,01), prolongación de la internación y del tiempo de tratamiento (p≤0,001)

Introduction. Pseudomonas aeruginosa (PAE) associated bacteremia is uncommon in children. Objective. To describe the epidemiological, clinical, and microbiological features and outcome in children with PAE-associated bacteremia. Methods. A retrospective cohort study. Results. 100 patients (p) were included. Median age was 27 months (IQR 6-88). Overall 93 p (93%) had an underlying disease, 36 of whom had neutropenia. Eighty-five p (85%) had received antibiotics over the previous month, 60 (60%) had undergone previous invasive procedures, and 81 (81%) had been previously admitted. Forty-two p (42%) were admitted because of septic shock, 56 p (56%) were admitted to the intensive care unit (ICU), and 49 (49%) required mechanical ventilation (MV). Seventeen p (17%) had primary bacteremia, 15 p (15%) had catheter-related bacteremia, and 68 p (68%) had secondary bacteremia. The most common focus was mucocutaneous (21 p), followed by pulmonary (20 p). Emperical treatment was adequate in 84 p (84%). Resistance to one or more groups of antibiotics was observed in 38% of the cases; 11% were multiresistant and 15% were only resistant to carbapenems. Thirty-one p (31%) died. In our series, Pseudomonas aeruginosa resistant to carbapenems only or combined with other antibiotics was associated with previous exposition to antibiotics (p≤0.03), inadequate initial emperical treatment (p≤0.006), and higher mortality (p≤0.01), and longer hospital stay and treatment duration (p≤0.001)

Incidencia de bacterias multi-resistentes en unidades de cuidados intensivos de hospitales chilenos / Incidence of multi-resistant bacteria in Intensive Care Units of Chilean hospitals

Resumen Introducción: La vigilancia de incidencia de bacterias multi-resistentes es un indicador que permite estimar mejor la magnitud de la resistencia bacteriana en los servicios hospitalarios. Objetivo: Evaluar la incidencia de bacterias multi-resistentes relevantes en unidades de cuidados intensivos del país y establecer las diferencias entre población adulta y pediátrica. Metodología: Se solicitó a los hospitales participantes información del número de aislados de siete bacterias multi-resistentes epidemiológicamente relevantes de unidades de cuidados intensivos (UCI) de adulto y pediátrico entre enero de 2014 y octubre de 2015, y el número de días-cama ocupados en dichas unidades en el mismo período. Con estos datos se calculó incidencia por 1.000 pacientes-día para cada unidad. Resultados: Se recibió información de 20 UCI adultos y 9 UCI pediátricas. En UCI adultos las bacterias de mayor incidencia fueron K. pneumoniae productora de BLEE [4,72 × 1.000 días cama (1,21-13,89)] y S. aureus resistente a oxacilina [3,85 (0,71-12,66)]. En pediatría la incidencia fue menor, destacando K. pneumoniae productora de BLEE [2,71 (0-7,11)] y P. aeruginosa resistente a carbapenémicos [1,61 (0,31-9,25)]. Conclusión: Se observan importantes diferencias entre los distintos hospitales en la incidencia de las bacterias estudiadas. La incidencia de bacterias multi-resistentes en UCI de adultos es significativamente mayor que en UCI pediátrica para la mayoría de las bacterias estudiadas.

Introduction: Incidence of multi-resistant bacteria is an indicator that permits better estimation of the magnitude of bacterial resistance in hospitals. Aim: To evaluate the incidence of relevant multi-drug resistant bacteria in intensive care units (ICUs) of Chile. Methods: Participating hospitals submitted information about the number of isolates from infected or colonized patients with 7 epidemiologically relevant multi-resistant bacteria in adult and pediatric ICUs between January 1, 2014 and October 31, 2015 and the number of bed days occupied in these units in the same period was requested. With these data incidence was calculated per 1,000 patient days for each unit. Results: Information from 20 adults and 9 pediatric ICUs was reviewed. In adult ICUs the bacteria with the highest incidence were K. pneumoniae ESBL [4.72 × 1,000 patient day (1.21-13.89)] and oxacillin -resistant S. aureus [3.85 (0.71-12.66)]. In the pediatric units the incidence was lower, highlighting K. pneumoniae ESBL [2.71 (0-7.11)] and carbapenem -resistant P. aeruginosa [1.61 (0.31-9.25)]. Conclusion: Important differences between hospitals in the incidence of these bacteria were observed. Incidence of multi-resistant bacteria in adult ICU was significantly higher than in pediatric ICU for most of the studied bacterias.

Detection of multidrug-resistant Pseudomonas aeruginosa harboring bla GES-1 and bla GES-11 in Recife, Brazil

Abstract INTRODUCTION: Pseudomonas aeruginosa, an important pathogen globally, presents several resistance mechanisms. This study aimed to investigate the presence of bla GES in clinical isolates of Pseudomonas aeruginosa obtained from various clinical specimens from patients admitted to three different hospitals in Recife, Brazil. The Guiana extended spectrum beta-lactamase (GES) enzymes are responsible for conferring broad spectrum resistance to beta-lactam drugs, including the carbapenems. METHODS: A total of 100 carbapenem-resistant P. aeruginosa isolates underwent polymerase chain reaction (PCR) testing to identify bla GES, bla KPC, bla SPM-1, bla IMP, and bla VIM. Additionally, PCR products positive for bla GES were sequenced. The clonal profiles of these same isolates were then determined by means of enterobacterial repetitive intergenic consensus (ERIC)-PCR analysis. RESULTS: PCR analysis revealed that four isolates harbored bla GES; DNA sequencing showed that two harbored bla GES-1 and two bla GES-11. Beta-lactamase genes bla SPM-1, bla IMP, bla VIM, and bla KPC were investigated; none of these genes was detected. Automated susceptibility testing methods (Vitek®2, bioMérieux) showed that the bla GES-1-positive isolates were only susceptible to polymyxin B. The patterns obtained with ERIC-PCR methods showed clonal relationship between the two isolates that harbored bla GES-11, whereas different clonal profiles were found in the isolates harboring bla GES-1. CONCLUSIONS: We detected the presence of bacterial isolates positive for two different variants of the enzyme GES in three different hospitals from Recife, Brazil. These enzymes have a great capacity for dissemination among Gram-negative bacteria and confer broad-spectrum resistance to beta-lactam antibiotics and to the carbapenems.

Detection of tuberculosis drug resistance: a comparison by Mycobacterium tuberculosis MLPA assay versus Genotype®MTBDRplus

BACKGROUND To cope with the emergence of multidrug-resistant tuberculosis (MDR-TB), new molecular methods that can routinely be used to screen for a wide range of drug resistance related genetic markers in the Mycobacterium tuberculosis genome are urgently needed. OBJECTIVE To evaluate the performance of multiplex ligaton-dependent probe amplification (MLPA) against Genotype® MTBDRplus to detect resistance to isoniazid (INHr) and rifampicin (RIFr). METHOD 96 culture isolates characterised for identification, drug susceptibility testing (DST) and sequencing of rpoB, katG, and inhA genes were evaluated by the MLPA and Genotype®MTBDRplus assays. RESULTS With sequencing as a reference standard, sensitivity (SE) to detect INHr was 92.8% and 85.7%, and specificity (SP) was 100% and 97.5%, for MLPA and Genotype®MTBDRplus, respectively. In relation to RIFr, SE was 87.5% and 100%, and SP was 100% and 98.8%, respectively. Kappa value was identical between Genotype®MTBDRplus and MLPA compared with the standard DST and sequencing for detection of INHr [0.83 (0.75-0.91)] and RIFr [0.93 (0.88-0.98)]. CONCLUSION Compared to Genotype®MTBDRplus, MLPA showed similar sensitivity to detect INH and RIF resistance. The results obtained by the MLPA and Genotype®MTBDRplus assays indicate that both molecular tests can be used for the rapid detection of drug-resistant TB with high accuracy. MLPA has the added value of providing information on the circulating M. tuberculosis lineages.

Actividad de cobre sobre cocáceas grampositivas multi-resistentes a los antibióticos aisladas en hospitales chilenos / Copper activity against multiresistant Gram-positive cocci isolated in Chilean hospitals

Background: Nosocomial infections caused by multiresistant Gram-positive cocci are a serious problem for public health systems worldwide. The use of copper surfaces in hospital environments has proven to be an effective alternative for the control of various microorganisms, including multiresistant nosocomial pathogens. Aim: To determine the association between antibiotic multiresistance and higher levels of copper tolerance in Gram-positive cocci isolated from Chilean hospitals, which might confer a selective advantage in environments with copper. Methods: The ionic copper tolerance levels were evaluated using the Mueller Hinton agar dilution method, in S. aureus and Enterococcus spp. strains with different levels of susceptibility to clinically relevant antibiotics. Results: A statistically significant association between higher levels of tolerance to copper ion and multi-resistance to antibiotics in Enterococcus spp. was observed.

Introducción: Las infecciones nosocomiales, producidas por bacterias cocáceas grampositivas multi-resistentes constituyen un serio problema para los sistemas de salud pública mundial. El uso de superficies de cobre en ambientes hospitalarios ha demostrado ser una alternativa efectiva para el control de diversos microorganismos, incluyendo patógenos nosocomiales multi-resistentes. Objetivo: Determinar la asociación entre la multi-resis-tencia a antimicrobianos y mayores niveles de tolerancia a cobre en bacterias cocáceas grampositivas aisladas de hospitales chilenos, que podrían conferir una ventaja selectiva en ambientes cobrizados. Material y Métodos: Se evaluó los niveles de tolerancia a cobre iónico en grupos de cepas de Staphylococcus aureus y Enterococcus spp. con distintos grados de susceptibilidad a antimicrobianos de relevancia clínica, mediante el método de dilución en agar Mueller Hinton. Resultados: Se observó una asociación estadísticamente significativa entre mayores niveles de tolerancia a cobre iónico y la multi-resistencia a antimicrobianos en Enterococcus spp.

A randomized clinical trial on the effectiveness of a symbiotic product to decolonize patients harboring multidrug-resistant Gram-negative bacilli

Abstract INTRODUCTION: We aimed to evaluate the effectiveness of a symbiotic product to decolonize the intestinal tract of patients harboring multidrug-resistant (MDR) Gram-negative bacilli and to prevent nosocomial infections. METHODS: This was a randomized, double blind, placebo-controlled clinical trial, conducted in a tertiary-care university hospital. All adult hospitalized patients with a positive clinical culture and a positive rectal swab for any MDR Gram-negative bacilli were potentially eligible. Exclusion criteria were pregnancy, immunosuppression, and bowel obstruction/perforation. The intervention consisted of administering a symbiotic product (Lactobacillus bulgaricus, Lactobacillus rhamnosus, and fructo-oligosaccharides) twice a day for seven days via the oral/enteral route. RESULTS: Between August 1, 2012 and December 22, 2013, 116 of 275 eligible patients were allocated to treatment (n=57) and placebo (n=59). Overall, 101 patients received at least four doses of the study products and were included in the modified intention-to-treat analysis. The primary study outcome, a negative rectal swab for MDR Gram-negative bacilli after treatment, was identified in 16.7% (8/48) and 20.7% (11/53) of patients in the experimental and placebo group, respectively (p=0.60). The secondary outcome, the combined incidence of nosocomial respiratory and urinary tract infections, was 37.5% (18/48) in the experimental group versus 22.6% (12/53) in the control group (adjusted odds ratio: 1.95, 95% confidence interval: 0.69-5.50, p=0.21). Length of stay after the beginning of the intervention, incidence of adverse events, and in-hospital mortality rates were similar in both study groups. CONCLUSIONS: Under the present study conditions, symbiotic administration was not effective for decolonizing hospitalized patients harboring MDR Gram-negative bacilli.

Evaluation of crystal violet decolorization assay for minimal inhibitory concentration detection of primary antituberculosis drugs against Mycobacterium tuberculosis isolates

In this study we evaluated the crystal violet decolorization assay (CVDA) for detection of minimum inhibitory concentration (MIC) of antituberculosis drugs. 53 isolates were tested in this study and 13 of them were multidrug resistant (MDR) isolates. The antibiotics concentrations were 2-0.06 mg/L for isoniazid (INH) and rifampicin (RIF) and were 16-0.25 mg/L for streptomycin (STM) and ethambutol (EMB). Crystal violet (CV-25 mg/L) was added into the microwells on the seventh day of incubation and incubation was continued until decolorization. Decolorization of CV was the predictor of bacterial growth. Overall agreements for four drugs were detected as 98.1%, and the average time was detected as 9.5 ± 0.89 day after inoculation. One isolate for INH and two isolates for STM were determined resistant in the reference method, but susceptible by the CVDA. One isolate was susceptible to EMB by the reference method, but resistant by the CVDA. All results were concordant for RIF. This study shows that CVDA is a rapid, reliable and suitable for determination of MIC values of Mycobacterium tuberculosis. And it can be used easily especially in countries with limited-sources.

Phenotypic and molecular characterization of resistance to macrolides, lincosamides and type B streptogramin of clinical isolates of Staphylococcus spp. of a university hospital in Recife, Pernambuco, Brazil

Abstract Introduction There is a mechanism of macrolide resistance in Staphylococcus spp. which also affects the lincosamides and type B streptogramins characterizing the so-called MLSB resistance, whose expression can be constitutive (cMLSB) or inducible (iMLSB) and is encoded mainly by ermA and ermC genes. The cMLSB resistance is easily detected by susceptibility testing used in the laboratory routine, but iMLSB resistance is not. Therapy with clindamycin in cases of infection with isolated iMLSB resistance may fail. Objective To characterize the phenotypic (occurrence of cMLSB and iMLSB phenotypes) and molecular (occurrence of ermA and ermC genes) profiles of MLSB resistance of clinical isolates of susceptible and methicillin-resistant Staphylococcus aureus and CNS (coagulase-negative Staphylococcus) from patients of a university hospital, in Pernambuco. Methods The antimicrobial susceptibility of 103 isolates was determined by the disk diffusion technique in Mueller–Hinton agar followed by oxacillin screening. The iMLSB phenotype was detected by D test. Isolates with cMLSB and iMLSB phenotypes were subjected to polymerase chain reaction (PCR) for the detection of ermA and ermC genes. Results The cMLSB and iMLSB phenotypes were respectively identified in 39 (37.9%) and five (4.9%) isolates. The iMLSB phenotype was found only in four (10.8%) methicillin-susceptible S. aureus and one (4.5%) methicillin-resistant S. aureus. In the 44 isolates subjected to PCR, four (9.1%) only ermA gene was detected, a lower frequency when compared to only ermC 17 (38.6%) gene and to one (2.3%) isolate presenting both genes. Conclusion In the Staphylococcus spp. analyzed, the ermC gene was found more often than the ermA, although the iMLSB phenotype had been less frequent than the cMLSB. It was important to perform the D test for its detection to guide therapeutic approaches.

Effects of the encapsulation of usnic acid into liposomes and interactions with antituberculous agents against multidrug-resistant tuberculosis clinical isolates

Mycobacterium tuberculosis (Mtb) has acquired resistance and consequently the antibiotic therapeutic options available against this microorganism are limited. In this scenario, the use of usnic acid (UA), a natural compound, encapsulated into liposomes is proposed as a new approach in multidrug-resistant tuberculosis (MDR-TB) therapy. Thus the aim of this study was to evaluate the effect of the encapsulation of UA into liposomes, as well as its combination with antituberculous agents such as rifampicin (RIF) and isoniazid (INH) against MDR-TB clinical isolates. The in vitro antimycobacterial activity of UA-loaded liposomes (UA-Lipo) against MDR-TB was assessed by the microdilution method. The in vitro interaction of UA with antituberculous agents was carried out using checkerboard method. Minimal inhibitory concentration values were 31.25 and 0.98 µg/mL for UA and UA-Lipo, respectively. The results exhibited a synergistic interaction between RIF and UA [fractional inhibitory concentration index (FICI) = 0.31] or UA-Lipo (FICI = 0.28). Regarding INH, the combination of UA or UA-Lipo revealed no marked effect (FICI = 1.30-2.50). The UA-Lipo may be used as a dosage form to improve the antimycobacterial activity of RIF, a first-line drug for the treatment of infections caused by Mtb.

In Vitro Interactions of Antibiotic Combinations of Colistin, Tigecycline, and Doripenem Against Extensively Drug-Resistant and Multidrug-Resistant Acinetobacter baumannii

BACKGROUND: Acinetobacter baumannii infections are difficult to treat owing to the emergence of various antibiotic resistant isolates. Because treatment options are limited for multidrug-resistant (MDR) A. baumannii infection, the discovery of new therapies, including combination therapy, is required. We evaluated the synergistic activity of colistin, doripenem, and tigecycline combinations against extensively drug-resistant (XDR) A. baumannii and MDR A. baumannii. METHODS: Time-kill assays were performed for 41 XDR and 28 MDR clinical isolates of A. baumannii by using colistin, doripenem, and tigecycline combinations. Concentrations representative of clinically achievable levels (colistin 2 microg/mL, doripenem 8 microg/mL) and achievable tissue levels (tigecycline 2 microg/mL) for each antibiotic were used in this study. RESULTS: The colistin-doripenem combination displayed the highest rate of synergy (53.6%) and bactericidal activity (75.4%) in 69 clinical isolates of A. baumannii. Among them, thedoripenem-tigecycline combination showed the lowest rate of synergy (14.5%) and bacteri-cidal activity (24.6%). The doripenem-tigecycline combination showed a higher antagonistic interaction (5.8%) compared with the colistin-tigecycline (1.4%) combination. No antagonism was observed for the colistin-doripenem combination. CONCLUSIONS: The colistin-doripenem combination is supported in vitro by the high rate of synergy and bactericidal activity and lack of antagonistic reaction in XDR and MDR A. baumannii. It seems to be necessary to perform synergy tests to determine the appropri-ate combination therapy considering the antagonistic reaction found in several isolates against the doripenem-tigecycline and colistin-tigecycline combinations. These findings should be further examined in clinical studies.

In Vitro Synergistic Effects of Antimicrobial Combinations on Extensively Drug-Resistant Pseudomonas aeruginosa and Acinetobacter baumannii Isolates

BACKGROUND: Extensively drug-resistant (XDR) Pseudomonas aeruginosa and Acinetobacter baumannii are a threat to hospitalized patients. We evaluated the effects of antimicrobial combinations on XDR P. aeruginosa and A. baumannii isolates. METHODS: P. aeruginosa and A. baumannii isolates, which were resistant to all antibiotics except colistin (CL), were collected from eight hospitals in Korea. Genes encoding metallo-beta-lactamases (MBLs) and OXA carbapenemases were detected by PCR in eight P. aeruginosa and 30 A. baumannii isolates. In vitro synergy of antimicrobial combinations was tested by using the checkerboard method. RESULTS: Minimum inhibitory concentrations of beta-lactams, aminoglycosides, and fluoroquinolones were very high, while that of CL was low for majority of XDR P. aeruginosa and A. baumannii isolates. Antimicrobial combinations including Imipenem (IPM)-CL, ceftazidime (CAZ)-CL, and rifampin (RIF)-CL exerted only additive/indifferent effects on majority of XDR P. aeruginosa isolates. Proportions of XDR A. baumannii isolates that showed synergistic and additive/indifferent inhibition after treatment with antimicrobial combinations used are as follows: IPM-ampicillin-sulbactam (AMS), 17% and 80% isolates, respectively; IPM-rifampin (RIF), 13% and 81% isolates, respectively; IPM-CL, 13% and 87% isolates, respectively; and RIF-COL, 20% and 73% isolates, respectively. Significant proportion (19%) of XDR P. aeruginosa isolates produced MBLs, and majority (82%) of A. baumannii isolates produced either MBLs or OXA-23. CONCLUSIONS: Our results suggest that combinations of IPM-AMS, IPM-RIF, IPM-CL, and RIF-CL are more useful than individual drugs for treating 13-20% of XDR A. baumannii infections.

Draft genome sequence of Inquilinus limosus strain MP06, a multidrug-resistant clinical isolate

The bacterium, Inquilinus limosus, with its remarkable antimicrobial multiresistant profile, has increasingly been isolated in cystic fibrosis patients. We report draft genome sequence of a strain MP06, which is of considerable interest in elucidating the associated mechanisms of antibiotic resistance in this bacterium and for an insight about its persistence in airways of these patients.