ABSTRACT
Multidrug resistance of Gram-negative bacilli is a major problem globally. However, little is known about the combined probability of resistance to various antibiotics. In this study, minimum inhibitory concentrations of widely used antibiotics were determined using clinical isolates of Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii, randomly chosen from strain collections created during 1999-2009 in tertiary medical institutions in Seoul, South Korea. To analyze combined efficacy of antibiotics against a subgroup of isolates, conditional probabilities were determined based on arbitrary, non-independent patterns of antimicrobial susceptibility and resistance. Multidrug resistance, defined as resistance to three or more classes of antibiotics, was observed in the following order: A. baumannii (96%), P. aeruginosa (65%), E. coli (52%), and K. pneumoniae (7%). A. baumannii strains resistant to gentamicin were found to be resistant to a number of antibiotics, except for colistin and polymyxin B. Resistance to gentamicin following exposure to this antibiotic was highly likely to lead to multidrug resistance in all four microbes. This study shows a causal relationship between gentamicin resistance and the prevalence of multidrug resistance in clinical isolates of Gramnegative bacilli in South Korea during 1999-2009 and suggests the importance of prudent use of gentamicin in hospitals.
Subject(s)
Acinetobacter baumannii/drug effects , Drug Resistance, Multiple, Bacterial , Escherichia coli/drug effects , Klebsiella pneumoniae/drug effects , Pseudomonas aeruginosa/drug effects , Acinetobacter baumannii/isolation & purification , Anti-Bacterial Agents/pharmacology , Escherichia coli/isolation & purification , Gentamicins/pharmacology , Humans , Klebsiella pneumoniae/isolation & purification , Models, Statistical , Pseudomonas aeruginosa/isolation & purification , Seoul , Tertiary Care CentersABSTRACT
Nosocomial bacteremia is a major cause of hospital infection, associated with high rate of morbidity and mortality, prolonged hospital stay and higher costs. However, few prospective studies analyse the prognostic factors associated with mortality of gramnegative rods bloodstream infections in hospital wards outside of intensive care units. A prospective/descriptive study was conducted from March to December 2006. All patients with nosocomial-acquired bloodstream infection due to gramnegative rods were included. Epidemiology and clinical features were analysed as potential prognostic factors for mortality. During the study period, 84 cases were detected, being A. baumannii, Burkholderia sp and E. coli the most frequent isolates, with a mortality of 48 percent>. Bacteremia derived from a high-mortality associated septic focus (RR 4.9, IC95 percent> 1.3 - 18.8) and admissionto intensive care unit (RR 4.78, IC95 percent> 1.7- 13.1) were independent variables associated with mortality. Inappropriate empirical antibiotic treatment was not associated with greater risk of mortality. Nosocomial gramnegative bloodstream infections in our series were mainly due to non-fermentative bacilli and were associated with high mortality rates when their origin was a high risk septic focus or the patient was admitted to intensive care unit.
La bacteriemia nosocomial es una causa importante de infección intrahospitalaria, asociada a alta morbi-mortalidad, pero pocos estudios examinan en forma prospectiva las bacteriemias por bacilos grammne-gativos (BGN) más allá de las áreas de cuidados intensivos. Se realizó un estudio descriptivo, prospectivo desde marzo a diciembre del 2006, reclutando todos los pacientes con bacteriemia por BGN de origen intra-hospitalario. Se analiza la epidemiología y características clínicas como potenciales factores pronósticos de mortalidad. En el período de estudio se detectaron 84 casos (los más frecuentes A. baumannii, Burkholderia sp. y E. coli), con una mortalidad de 48 por ciento. La bacteriemia derivada de un foco infecciosos asociada a alta mortalidad (RR 4.9, IC95 por ciento 1,3-18,8) y la internación en UCI (RR 4,78, IC95 por ciento 1,7-13,1) fueron variables independientes predictoras de mortalidad. El tratamiento antimicrobiano empírico inadecuado no se asoció a mayor mortalidad. La bacteriemia nosocomial por BGN en nuestra serie se debió principalmente a bacilos no fermentadores y ésta se asoció con alta mortalidad cuando el origen fue un foco de alto riesgo o el paciente se encontraba internado en la UCI.
