Browsing by Author "Wozniak, Aniela"
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- ItemAnálisis de los fenotipos y genotipos de resistencia a eritromicina y clindamicina en cepas de Streptococcus pyogenes aisladas en Chile en un período de 10 años(2011) Rodríguez, Carlos; Rojas, Pablo; Wozniak, Aniela; Kalergis, Alexis M.; Cerón, Inés; Riedel, Ingrid; Román, Juan C.; Villarroel, Luis A.; Berríos, Ximena; Bavestrello, Luis; García, PatriciaBackground: Macrolide and lincosamide resistance in Streptococcus pyogenes is due to the acquisition of mef, ermB and ermA genes, which confer different resistance phenotypes, namely M, MLSBconstitutive and MLSBinducible respectively. The last report of resistance in Chile was done in the period 1990-1998, in which resistance to macrolides was 5.4%, with M phenotype as the predominant one. Aim: To characterize the evolution of erythromycin and clindamycin resistance and their associated genes in S. pyogenes strains isolated from patients with invasive and noninvasive infections in the period 1996 to 2005. Material and Methods: Resistance to erythromycin and clindamycin was determined in 1,282 clinical isolates using the disk diffusion test. Resistant isolates were analyzed by polymerase chain reaction (PCR) for the presence of the above mentioned resistance genes. Results: Global resistance to erythromycin and clindamycin was 3.5 and 0.7% respectively. Eighty percent of the resistant strains possessed the M. phenotype. Conclusions: Resistance levels of S. pyogenes have decreased in Chile in the last years. Most resistant strains have M phenotype in contrast to many countries in which the MLSB constitutive phenotype is the predominant one.
- ItemCatheter-associated bloodstream infection caused by Leifsonia aquatica in a haemodialysis patient: a case report(SOC GENERAL MICROBIOLOGY, 2012) Porte, Lorena; Soto, Andres; Andrighetti, Daniela; Dabanch, Jeannette; Braun, Stephanie; Saldivia, Alejandra; Carlos Flores, Juan; Wozniak, Aniela; Garcia, Patricia; Weitzel, ThomasLeifsonia aquatica is an aquatic coryneform rod that is capable of forming biofilms in environmental water sources. It has rarely been associated with human infections and its pathogenicity and clinical significance are uncertain. We describe a case of catheter-related bloodstream infection in a haemodialysis patient. The isolate grew on conventional media as a yellow-pigmented colony, but identification required molecular methods. Although the strain displayed reduced sensitivity to vancomycin, the clinical outcome was favourable after catheter removal and intravenous treatment with this antibiotic. Our report gives further evidence of the capability of this aquatic bacterium to cause human infection.
- ItemDoes a clinical prediction rule anticipate the diagnosis for streptococcal pharyngitis in children aged 2 to 15?(SOC CHILENA INFECTOLOGIA, 2018) Katzulovic, Lorena; Garcia, Patricia; Wozniak, Aniela; Villarroel, Luis; Hirsch, Tamara; Concha, Ida; Catalan, Silvia; Cifuentes, LorenaBackground: The etiology of a streptococcal pharyngitis must be documented by laboratory techniques to avoid unnecessary antimicrobial treatment, but this strategy increases cost for the patient. Available scores applied in children or adults are imperfect. Aim: To develop a clinical prediction rule to aid the diagnostic process of streptococcal pharyngitis (SP) in children in a low-resource setting. Methods: Three hundred and eighteen patients aged 2 to 15 years who were evaluated for suspected SP at the Pediatric Emergency Department and the Pediatric Ambulatory Unit of Red Salud UC-Christus entered the study. A throat culture and a rapid antigen detection test for Streptococcus pyogenes were obtained from each patient. Data were analyzed for possible clinical predictors of SP with univariate and multiple regression analyses. Results: Seventy-three cases of SP were diagnosed (23.9%). In the univariate analysis, fever was inversely associated with SP (p = 0.002). Odynophagia, palatal petechiae, and season of the year (autumn and winter) were positively associated with SP (p = 0.007, p < 0.001 and p = 0.03 respectively). In multiple regression analysis the models did not have sufficient power to predict streptococcal etiology. Conclusion: Clinical predictors, even those systematically included in clinical prediction rules, did not show sufficient predictive power to safely include or exclude SP in this setting, and thus, it is necessary to improve access to confirmatory tests.
- ItemEfficient Lung Recruitment of Respiratory Syncytial Virus-Specific Th1 Cells Induced by Recombinant Bacillus Calmette-Guerin Promotes Virus Clearance and Protects from Infection(AMER ASSOC IMMUNOLOGISTS, 2010) Cautivo, Kelly M.; Bueno, Susan M.; Cortes, Claudia M.; Wozniak, Aniela; Riedel, Claudia A.; Kalergis, Alexis M.Infection by the respiratory syncytial virus (RSV) can cause extensive inflammation and lung damage in susceptible hosts due to a Th2-biased immune response. Such a deleterious inflammatory response can be enhanced by immunization with formalin- or UV-inactivated RSV, as well as with vaccinia virus expressing the RSV-G protein. Recently, we have shown that vaccination with rBCG-expressing RSV Ags can prevent the disease in the mouse. To further understand the immunological mechanisms responsible for protection against RSV, we have characterized the T cell populations contributing to virus clearance in mice immunized with this BCG-based vaccine. We found that both CD4(+) and CD8(+) T cells were recruited significantly earlier to the lungs of infected mice that were previously vaccinated. Furthermore, we observed that simultaneous adoptive transfer of CD8(+) and CD4(+) RSV-specific T cells from vaccinated mice was required to confer protection against virus infection in naive recipients. In addition, CD4(+) T cells induced by vaccination released IFN-gamma after RSV challenge, indicating that protection is mediated by a Th1 immune response. These data suggest that vaccination with rBCG-expressing RSV Ags can induce a specific effector/memory Th1 immune response consisting on CD4(+) and CD8(+) T cells, both necessary for a fully protective response against RSV. These results support the notion that an effective induction of Th1 T cell immunity against RSV during childhood could counteract the unbalanced Th2-like immune response triggered by the natural RSV infection. The Journal of Immunology, 2010, 185: 7633-7645.
- ItemPorin alterations present in non-carbapenemase-producing Enterobacteriaceae with high and intermediate levels of carbapenem resistance in Chile(SOC GENERAL MICROBIOLOGY, 2012) Wozniak, Aniela; Villagra, Nicolas A.; Undabarrena, Agustina; Gallardo, Natalia; Keller, Nicole; Moraga, Marcela; Roman, Juan C.; Mora, Guido C.; Garcia, PatriciaThe main goal of this work was to identify the mechanisms responsible for carbapenem resistance in 61 Chilean clinical isolates of Enterobacteriaceae (Enterobacter spp., Serratia marcescens, Morganella morganii, Escherichia coli and Klebsiella pneumoniae) with reduced susceptibility to at least one carbapenem (ertapenem, imipenem or meropenem). All of the isolates were analysed for the presence of carbapenemases, extended spectrum beta-lactamases (ESBLs), AmpC enzymes and outer-membrane proteins. None of the isolates exhibited carbapenemase activity nor did they have any of the carbapenemase genes that were screened for. Most of the 61 strains produced at least one ESBL and/or one AmpC enzyme and either lost their porins or had altered porins according to sequence analysis. The distribution of ESBLs and AmpC enzymes was different among the species studied. Resistance in K. pneumoniae and E. coli isolates was associated with ESBLs; in M. morganii isolates, resistance was attributed to overexpression of an AmpC enzyme; and in Enterobacter spp. isolates, resistance was associated with both types of enzymes. In K. pneumoniae isolates, porin integrity was more a determinant of carbapenem resistance than the presence of ESBLs, whereas in isolates of Enterobacter spp., M. morganii and S. marcescens, the presence of an overexpressed AmpC enzyme was associated with higher imipenem and meropenem MIC values. Therefore, carbapenem resistance in Chilean isolates is not due to true carbapenemases but rather to a combination of porin loss/alteration and beta-lactamase activity. The fact that carbapenemases were not detected in this study is unique, given that many countries in the region have already reported the presence of these enzymes.
- ItemPresence of Bordetella holmesii in an outbreak of pertussis in Chile(SOC CHILENA INFECTOLOGIA, 2013) Miranda, Carolina; Wozniak, Aniela; Castillo, Claudia; Geoffroy, Enrique; Zumaran, Cecilia; Porte, Lorena; Roman, Juan C.; Potin, Marcela; Garcia, PatriciaThe incidence of whooping cough in Chile ranges from 4.1 and 7.5 per hundred thousand inhabitants. B. pertussis detection is performed by Real Time PCR (Q-PCR) directed to the insertion sequence IS481. However, this sequence is also found in the genome of B. bronchiseptica and B. holmesii. The latter is also a respiratory pathogen whose clinical features are similar to B. pertussis. However, it is important to differentiate between these species because in immunosuppressed patients B. holmesii is more likely to cause bacteremia and is less susceptible to erythromycin. The goal of this work is to measure prospectively and retrospectively the presence of B. holmesii in samples reported positive for B. pertussis in the period 2010-2011. During this period, 1994 nasopharyngeal specimens entered the laboratory for Bordetella sp. PCR, of which 224 were positive. The analysis by Q-PCR directed to the recA gene of B. holmesii of all 224 positive samples determined a prevalence of B. holmesii of 0.6% (12/1994). Because of its more aggressive behavior in immunosupressed patients and its different resistance pattern, routine screening of B. pertussis and B. holmesii is currently performed for all samples in which Bordetella sp PCR is initially detected.
- ItemTest evaluation and strategy proposal to detect and to characterize carbapenemase-producing gram negative bacilli(SOC CHILENA INFECTOLOGIA, 2017) Munoz, Constanza; Zumaran, Cecilia; Gonzalez, Tamara; Wozniak, Aniela; Castillo, Claudia; Garcia, PatriciaIntroduction: The detection of carbapenemase-producing gram negative bacilli is complicated, because there are available multiple options of test. The confirmation of the enzyme by molecular characterization is not available in all laboratories in our country. Objective: To propose a fast, efficient and simple strategy to detect and confirm CPB. Materials and Methods: 39 CPB isolates and 8 non-producing were used to evaluate the phenotypic test Carba NP, CarbAcineto NP and Blue-Carba, validating the test Xpert (R) Carba-R, to be used directly with bacterial colonies with conventional PCR. Results: The sensitivity of Carba NP, CarbAcineto NP and Blue-Carba was 79,5; 87,2 y 84,6%, respectively; and specificity was 79.5; 87.2 and 84.6%, respectively. The limit of detection of Xpert (R) Carba-R was different for each carbapenemasa: 40.8 ufc/reaction to KPC and NDM and 30.6 ufc/reaction to VIM. Discussion: On isolates with decreased susceptibility to carbapenems we propose to use as screening the test CarbAcineto NP, follow by Xpert (R) Carba-R to characterize the carbapenemase and adopt specific infection control measures.