ABSTRACT
The increase in methicillin-resistant Staphylococcus aureus (MRSA) infections has limited the use of efective available antibiotics. Clindamycin, an alternative against MRSA, might have inducible resistance that is not detected by common antibiograms. The disk diffusion method (D-test) detects the inducible resistance. Objetive: To establish the frecuency of inducible resistance in MRSA from blood and secretion samples obtained from hospitalyzed patients. Methods: Prospective and descriptive research, including MRSA positive blood and secretion samples from patients of Hospital Luis Calvo Mackenna, between July 2005-July 2006. A D-test was performed to the samples. Results: 220 MRSA samples were obtained and D-test was performed on 155 of them. 80 percent of the samples carne from tracheobronquial secretion and 90 percent> had used antibiotics. From all analyzed MRSA isolates, 32 (20.6 percento) were Clindamycin susceptible and 14 (43.8 percent) had Clindamycin inducible resistance (D-test+). Conclusions: A high percentage of MRSA Clindamycin resistant was found. From MRSA Clindamycin susceptible, 43.8 percent> had Clindamycin inducible resistance (D test+). D-test was implemented in the Microbiology Laboratory at Hospital Luis Calvo Mackenna, allowing the identification of MRSA isolates suceptible to Clindamicyn treatment.
El aumento de infecciones por Staphylococcus aureus meticilino resistente (SAMR) ha disminuido las alternativas de antimicrobianos efectivos. Clindamicina, una alternativa contra SAMR, puede presentar resistencia inducible no detectable con antibiogramas habituales. El test de difusión en disco (D test) detecta esta resistencia inducible. Objetivo: Determinar la frecuencia de resistencia inducible a clindamicina en muestras de sangre y/o secreciones positivas para SAMR de pacientes del hospital. Materiales y Métodos: Estudio prospectivo descriptivo, incluyó muestras de sangre y secreciones positivas para SAMR de pacientes del Hospital Luis Calvo Mackenna, recolectadas entre Julio 2005 y Julio 2006. A cada muestra se le realizó el D-test estandarizado según pautas CLSI. Resultados: Se recolectaron 220 cepas de SAMR, se realizó D test a 155. El 80 por ciento de las muestras era secreción tráqueo-bronquial. El 90 por ciento tenía antecedente de uso de antimicrobianos. Del total de cepas estudiadas, 32 (20,6 por ciento) resultó sensible a clindamicina y 14 (43,8 por ciento) presentaron resistencia inducible a clindamicina (D-test +). Discusión: Se encontró alto porcentaje de SAMR resistentes a clindamicina en nuestro medio hospitalario. Aquellos SAMR informados como sensibles a clindamicina, 43,8 por ciento presenta resistencia inducible a clindamicina (D-Test +). Se implemento en el Laboratorio de Microbiología la técnica de D test, permitiendo identificar cepas de SAMR susceptibles de tratar con clindamicina.
Subject(s)
Humans , Male , Infant , Child, Preschool , Child , Anti-Bacterial Agents/pharmacology , Clindamycin/pharmacology , Staphylococcal Infections/microbiology , Staphylococcus aureus , Drug Resistance, Bacterial , Microbial Sensitivity Tests , Prospective Studies , Staphylococcus aureus/isolation & purificationABSTRACT
Background: Shigella spp is a frequent cause of diarrhea in children. Antimicrobials decrease the duration of diarrhea and pathogen excretion. However, the increasing resistance limits their therapeutic value. Aim: To study Shigella serotype distribution in the Metropolitan Region in Chile, and its relationship with severity of disease, antimicrobial resistance pattern and clonality. Material and methods: During summer 2004-2005, stool samples from children with diarrhea were collected in Cary Blair transpon medium and cultured. Shigella isolates were serotyped using monoclonal and polyclonal commercial antibodies. In vitro activity of ampicillin, amoxicillin/clavulanic acid, chloramphenicol, cotrimoxazol, nalidixic acid, ciprofloxacin, ceftriaxone and azythromycin was determined by minimal inhibitory concentration (MIC). Clonality was studied by pulsed-field gel electrophoresis (PFGE) using Xbal as restriction enzyme. Results: One hundred thirty nine Shigella strains were isolated (77 S sonnei and 62 S flexneri). S sonnei and S flexneri 2a serotypes were responsible for 95 percent of episodes. Children aged 2-4 years, showed a greater incidence of Shigella infections and 77 percent of episodes were treated on an ambulatory basis. High resistance levels were observed for ampicillin, cotrimoxazole, amoxicillin-clavulanic acid and chloramphenicol (67 percent, 60 percent, 56 percent and 45 percent, respectively). We found 11 resistance patterns and 61,2 percent of strains were multiresistant. There were multiple clones without a strict relationship with resistance patterns. Conclusions: Shigella infections in Metropolitan Region in Chile are associated to a restricted number of serotypes, representing a clonal expansion associated to different antimicrobial resistant patterns.
Subject(s)
Child , Child, Preschool , Humans , Infant , Infant, Newborn , Anti-Bacterial Agents/pharmacology , Diarrhea/microbiology , Dysentery, Bacillary/microbiology , Shigella , Acute Disease , Chile/epidemiology , Diarrhea/diagnosis , Diarrhea/epidemiology , Drug Resistance, Multiple, Bacterial/genetics , Dysentery, Bacillary/diagnosis , Dysentery, Bacillary/epidemiology , Feces/microbiology , Microbial Sensitivity Tests , Seasons , Serotyping , Severity of Illness Index , Shigella/drug effects , Shigella/genetics , Urban PopulationABSTRACT
Background: Foodborne diseases are becoming an important cause of morbidity in Chile. In the Metropolitan Region of Chile, the Environmental Health Service started a surveillance program for foodborne diseases in 1994. In 2000, this program was complemented with an etiologic study of individuals involved in outbreaks. Aim: To report the incidence of foodborne outbreaks in the Metropolitan Region of Chile and its causative agents. Results: One hundred ninety outbreaks of foodborne diseases were reported in 1999 and 260 in 2000. The Southern Metropolitan health service had the higher incidence rates (7.5 in 1999 and 8.2 in 2000). The mean attack rates were 25 percent in both periods, affecting 1248 individuals in 1999 and 1774 in 2000. In 18 percent of outbreaks, a pathogen was identified; the most frequent agents were Salmonella Spp, Staphylococcus aureus and Shigella. In 15 percent of subjects, the cause was histamine or chemical agents. In the rest of the cases, the cause was not identified. The foods with higher risk of causing foodborne diseases were hot prepared dishes, home made goat cheese and meats. Conclusions: The incidence rates of foodborne disease in Metropolitan Area of Chile are high and maybe underestimate, only in a low rate of outbreaks was possible to have samples for etiologic studies. For a better understanding of this problem, timely notification of foodborne diseases must be encouraged and educational campaigns about the proper manipulation of food items must be implemented