In vitro antimicrobials activity against endemic Acinetobacter baumannii multiresistant clones

BACKGROUND: Multidrug-resistant strains of Acinetobacter baumannii have been reported increasingly around the world. The administration of an association of antibiotics has been proposed to create an active combination and to prevent the emergence of resistance. METHODOLOGY: The activity of colistin, rifampicin, gentamicin, imipenem and their associations was evaluated by means of killing curves in fourteen isolates belonging to three endemic PFGE types, in a university hospital of Buenos Aires city. The 14 isolates were selected on the basis of different mechanisms responsible for resistance to carbapenems and different susceptibility to colistin. RESULTS: The mechanism responsible for the resistance to imipenem was the production of OXA-23 and OXA-58 carbapenemases. Heteroresistance to colistin was observed in six isolates. The associations colistin-rifampicin and colistin-imipenem were synergistic in heteroresistant isolates and prevented the development of colistin-resistant mutants. The association imipenem-gentamicin was bactericidal in gentamicin susceptible isolates, whereas the association imipenem-rifampicin was always indifferent. CONCLUSION: The antimicrobial activity and the presence of synergy are related to the antimicrobials' susceptibilities irrespective of the PFGE type or the OXA-carbapenemase produced.Fil: Rodríguez, Carlos Hernán. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Bioquímica Clínica; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: De Ambrosio, Alejandra. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Bajuk, Milena. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Spinozzi, Mariela. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Nastro, Marcela. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Bioquímica Clínica; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Bombicino, Karina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Bioquímica Clínica; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Radice, Marcela Alejandra. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gutkind, Gabriel Osvaldo. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vay, Carlos. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Bioquímica Clínica; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Famiglietti, Ángela. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Bioquímica Clínica; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; Argentin

Identification and antibiotic susceptibility of viridans group streptococci isolates recovered from patients hospitalized at a teaching hospital in Buenos Aires City

Members of the viridans group streptococci (VGS) are the cause of local and invasive infections. Due to the severity of these infections and taking into account that reports regarding epidemiological aspects are scarce, the aims of this work were the identification and the study of the antibiotic susceptibility profiles of the isolates recovered from patients that were hospitalized in order to find out about the resistance level and the epidemiology of infections in which VGS are involved. A hundred and thirty two isolates identified as VGS were isolated at Hospital de Clínicas «José de San Martín» during the period 2011-2015. The identification was performed by biochemical test and mass spectrometry by Matrix Assisted Laser Desorption Ionization -Time of Flight Mass Spectrometry. Streptococcus anginosus group was prevalent (42%) followed by Streptococcus mitis group (33%). In the latter, isolates of Streptococcus pneumoniae were excluded. All the VGS isolates were susceptible to ertapenem, meropenem, linezolid and vancomycin; 25.8% were resistant (I+R) to penicillin, being prevalent in the S. mitis group. Regarding ceftriaxone and cefepime 96.9% of the isolates were susceptible. Only two isolates were resistant to levofloxacin, 27.2% to tetracycline and it was not found high level resistance to gentamycin (MIC range 0.5-32 μg/ml). Resistance to erythromycin was 17.4% with no significant difference between M and MLS phenotypes. The most active antibiotics were in addition to ceftriaxone and cefepime, vancomycin, ertapenem, meropenem and linezolid. These results highlight the importance of the continuous surveillance of the infections caused by VGS in order to predict a correct antibiotic therapy.Fil: Heine, Adriana C.. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: García, Susana. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Barberis, Claudia. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Vay, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Mollerach, Marta Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología; ArgentinaFil: Bonofiglio, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología; ArgentinaFil: Famiglietti, Ángela. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; Argentin

Neisseria meningitidis isolated from patients in men who have sex with men

En los períodos 2000-2004 y 2014-2015 se investigó la presencia de Neisseria meningitidis en 1.143 y 544 hombres que tienen sexo con hombres respectivamente, atendidos en el marco de un programa de enfermedades de transmisión sexual. Se determinó la prevalencia de este agente, su distribución en serogrupos y su sensibilidad a los antimicrobianos. Se obtuvieron hisopados faríngeos, rectales y uretrales, que se sembraron en medio selectivo Thayer Martin modificado. La identificación se realizó mediante pruebas bioquímicas convencionales y por espectrometría de masas (MALDI-TOF). En el segundo período estudiado, sobre 85 aislamientos procedentes de faringes se investigaron los serogrupos B, C, W e Y mediante PCR. Se determinó la CIM de penicilina, ceftriaxona, rifampicina, azitromicina y ciprofloxacina en 66 aislamientos obtenidos en el primer período y en 102 logrados en el segundo. La prevalencia de N. meningitidis fue del 17,8% en el primer período y del 28,1% en el segundo; este microrganismo se aisló más frecuentemente de fauces. Los serogrupos hallados fueron B (31,5%), Y (7,6%) y W (3,3%), con un 9,8% de aislamientos no capsulados; los restantes corresponderían a otros serogrupos. El 34,8% y el 63,7% de los aislados estudiados correspondientes al primer y segundo período, respectivamente, tuvieron sensibilidad intermedia a la penicilina, y un 11,8% de los evaluados en el segundo período fueron resistentes a dicho antibiótico. Todos los aislados estudiados fueron sensibles a ceftriaxona y a ciprofloxacina (excepto 3, con CIM entre 0,25 y 0,5g/ml), el 3% fueron resistentes a rifampicina y el 2% fueron no sensibles a azitromicina.La portación de N. meningitidis en hombres que tienen sexo con hombres fue elevada y hubo un alto porcentaje de cepas no sensibles a penicilina. El serogrupo B fue prevalente.During the periods 2000-2004 and 2014-2015, Neisseria meningitidis was investigated in men who have sex with men, 1143 and 544 respectively, who consulted in the sexually-transmitted disease program. Prevalence, serogroup distribution and susceptibility to antibiotics were determined. Pharyngeal, rectal and urethral swabs were cultivated on selective Thayer-Martin modified medium. The identification was performed by biochemical tests and mass spectrometry by MALDI-TOF. Serogroups B, C, W and Y were investigated by PCR in 85 isolates recovered from the pharynx belonging to the second period. MICs of penicillin, ceftriaxone, rifampicin, azithromycin and ciprofloxacin were determined for 66 and 102 isolates from periods 1 and 2 respectively, according to CLSI. The prevalence of N. meningitidis was 17.8% and 28.1%, in periods 1 and 2 respectively; the isolates were mainly recovered from the pharynx. The distribution of serogroups was B 31.5%; Y 7.6%; W 3.3% and 9.8% non-capsulated and the rest would belong to other serogroups. Isolates classified as intermediate to penicillin were 34.8% and 63.7% (first and second periods, respectively); moreover, 11.8% of the isolates from the second period were resistant. All isolates were susceptible to ceftriaxone, to ciprofloxacin (except 3 isolates with MIC values between 0.25 and 0.5g/ml), 3% were resistant to rifampicin and 2% were not susceptible to azithromicin. The prevalence of N. meningitidis carriage in men who have sex with men was high with a high rate of penicillin non-susceptible isolates. B was the prevalent serogroup.Fil: García, Susana Diana. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Sorhuet Pereira, Cecilia. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Perazzi, Beatriz Elizabeth. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Losada, Mirta Olga. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Cabellos Astorga, Gabriela. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Casco, Ricardo H.. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Vay, Carlos Alberto. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Mollerach, Marta Eugenia. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Famiglietti, Ángela M.R.. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; Argentin

Epidemiología molecular de aislamientos de Acinetobacter Baumannii en la ciudad de Guayaquil

Objetivo: describir brote causado por acinetobacter baumannii recuperado en dos centros asistenciales de la ciudad de Guayaquil, mediante técnicas de epidemiología molecular. Materiales y métodos: treinta y tres aislamientos de A. baumannii fueron recuperados de dos centros médicos de la ciudad de Guayaquil, Ecuador, entre noviembre de 2012 y octubre de 2013. Los aislamientos fueron identificados mediante MALDI-TOF y por la presencia de blaOXA-51. El análisis epidemiológico se realizó mediante PCR. Resultados: 33 aislamientos fueron sensibles solo a colistina. En 29 se detectó OXA-24/40. La secuenciación del ADN identificó a blaOXA-24/40 como blaOXA-72. Todos presentaron el mismo patrón de PCR. Conclusión: se presenta el primer brote de blaOXA-72 en aislados de A. baumannii en América del sur. Este es el primer estudio llevado a cabo en la República de Ecuador

Patógenos emergentes con alto impacto social : Programa 175

Fil: Famiglietti, Ángela. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaEn esta emisión, contamos con la participación de Ángela Famiglietti, Prof. Titular de la Cátedra de Microbiología Clínica (FFyB) y Jefa del Dpto. de Bioquímica Clínica y del Laboratorio de Bacteriología (Hospital de Clínicas - UBA), para reflexionar sobre los patógenos emergentes con alto impacto en la salud humana

Comparative Genomics Identifies Novel Genetic Changes Associated with Oxacillin, Vancomycin and Daptomycin Susceptibility in ST100 Methicillin-Resistant <i>Staphylococcus aureus</i>

Infections due to vancomycin-intermediate S. aureus (VISA) and heterogeneous VISA (hVISA) represent a serious concern due to their association with vancomycin treatment failure. However, the underlying molecular mechanism responsible for the hVISA/VISA phenotype is complex and not yet fully understood. We have previously characterized two ST100-MRSA-hVISA clinical isolates recovered before and after 40 days of vancomycin treatment (D1 and D2, respectively) and two in vitro VISA derivatives (D23C9 and D2P11), selected independently from D2 in the presence of vancomycin. This follow-up study was aimed at further characterizing these isogenic strains and obtaining their whole genome sequences to unravel changes associated with antibiotic resistance. It is interesting to note that none of these isogenic strains carry SNPs in the regulatory operons vraUTSR, walKR and/or graXRS. Nonetheless, genetic changes including SNPs, INDELs and IS256 genomic insertions/rearrangements were found both in in vivo and in vitro vancomycin-selected strains. Some were found in the downstream target genes of the aforementioned regulatory operons, which are involved in cell wall and phosphate metabolism, staphylococcal growth and biofilm formation. Some of the genetic changes reported herein have not been previously associated with vancomycin, daptomycin and/or oxacillin resistance in S. aureus

ß-lactamases produced by amoxicillin-clavulanate-resistant enterobacteria isolated in Buenos Aires, Argentina: A new blaTEMgene

Resistance to ß-lactam/ß-lactamase inhibitors in enterobacteria is a growing problem that has not been intensively studied in Argentina. In the present work, 54/843 enterobacteria collected in a teaching hospital of Buenos Aires city were ampicillin-sulbactam-resistant isolates remaining susceptible to second-and third-generation cephalosporins. The enzymatic mechanisms present in the isolates, which were also amoxicillin-clavulanic acid (AMC)-resistant (18/54) were herein analyzed. Sequencing revealed two different variants of blaTEM-1, being blaTEM-1b the most frequently detected allelle (10 Escherichia coli, 3 Klebsiella pneumoniae, 2 Proteus mirabilis and 1 Raoultella terrigena) followed by blaTEM-1a(1 K. pneumoniae). Amoxicillin-clavulanate resistance seems to be mainly associated with TEM-1 overproduction (mostly in E. coli) or co-expressed with OXA-2-like and/or SHV ß-lactamases (K. pneumoniae and P. mirabilis). A new blaTEMvariant (TEM-163) was described in an E. coli strain having an AMC MIC value of 16/8 µg/ml. TEM-163 contains Arg275Gln and His289Leu amino acid substitutions. On the basis of the high specific activity and low IC50 for clavulanic acid observed, the resistance pattern seems to be due to overproduction of the new variant of broad spectrumß-lactamase rather than to an inhibitor-resistant TEM (IRT)-like behavior