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Avaliação dos perfis de resistência a antibióticos em Escherichia coli provenientes de infeções urinárias adquiridas na comunidade
| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| DM_24906 | 2.48 MB | Adobe PDF |
Authors
Advisor(s)
Abstract(s)
As infeções do trato urinário (ITU) são das infeções mais frequentes na
comunidade, sendo E. coli o principal agente etiológico. O conhecimento da realidade
epidemiológica no que concerne aos padrões de suscetibilidade aos vários antibióticos
utilizados no tratamento de ITU é de extrema importância, permitindo assim a escolha
mais adequada em contexto de terapia empírica.
No tratamento da ITU são utilizados antibióticos de eliminação urinária,
nomeadamente -lactâmicos, quinolonas, sulfanamidas, fosfomicina e nitrofurantoína,
sendo os antibióticos do grupo dos -lactâmicos um dos mais utilizados no tratamento
de infeções causadas por Escherichia coli. No entanto, com o surgimento de bactérias
produtoras de -lactamases de espectro alargado (ESBLs), qAmpCs e/ou
carbapenemases a eficácia deste grupo de antimicrobianos tem vindo a diminuir. Os
genes codificantes destes mecanismos de resistência podem estar inseridos em
elementos móveis (plasmídeos) que podem incluir também genes de resistência a outros
grupos de antibióticos, limitando ainda mais as opções terapêuticas.
Com a realização do presente trabalho pretende-se avaliar os padrões de
suscetibilidade aos vários antibióticos utilizados no tratamento da ITU de 480 isolados
de E. coli provenientes de amostras de urina de pacientes que requisitaram exame
bacteriológico de urina em um laboratório da comunidade; investigar a ocorrência e a
diversidade de genes que codificam para ESBLs (blaESBL) ou qAmpC (blaqAmpC) nos
isolados identificados como presumíveis produtores de ESBLs e/ou qAmpC; assim
como avaliar a co-resistência a antibióticos não -lactâmicos nos isolados produtores de
ESBLs e/ou qAmpCs.
A identificação da espécie bacteriana e a avaliação da susceptibilidade aos vários
antibióticos foram realizadas utilizando o sistema automático VITEK®2 Systems. A
caracterização dos isolados identificados como presumíveis produtores de ESBLs
incluiu a realização do teste do duplo sinergismo e a identificação de genes blaESBL (blaTEM/blaSHV/blaCTX-M) por PCR e sequenciação. Nos isolados identificados como
possíveis produtores de qAmpC foi realizada a identificação de genes blaqAmpC por PCR
e sequenciação.
Nos 480 isolados de E. coli estudados, 94% foram provenientes de pacientes do
género feminino. A classe etária dos 61 aos 75 anos foi associada a uma maior
ocorrência de ITU em ambos os géneros. Na avaliação da susceptibilidade aos
diferentes antibióticos verificou-se uma elevada resistência à ampicilina (42,9%), ao
trimetropim-sulfametoxazol (23,1%) e a antibióticos do grupo das quinolonas,
destacando-se o ácido nalidixico (28,6%). As taxas de resistência à nitrofurantoína
(1,7%) ou à fosfomicina (2,1%) foram baixas, pelo que ambos constituiram ainda
alternativas eficazes no tratamento de ITU na comunidade. Nenhum isolado de E. coli
apresentou resistência aos carbapenemos.
A expressão de ESBLs foi observada em 3% (14/480) dos isolados de E. coli. Os
genes blaESBL foram identificados como blaCTX-M (blaCTX-M-14 e blaCTX-M-15) (n=12) ou
blaSHV (blaSHV-12) (n=2). Em 4 isolados de E. coli foi detetado um fenótipo compatível
com a produção de qAmpC, sendo que em todos foi identificado o gene blaCMY-2.
Verificou-se ainda a co-produção de ESBLs e qAmpC (blaSHV-12/blaCMY-2) (n=1). Em 12
dos isolados produtores de ESBLs e em 1 dos isolados produtores de qAmpC foram
observados fenótipos de multiresistência.
Este estudo demonstra que a disseminação na comunidade de E. coli resistentes
a múltiplos antibióticos é uma realidade preocupante, limitando as opções terapêuticas e
contribuindo para o insucesso do tratamento da ITU, sobretudo em contexto de terapia
empírica.
Urinary tract infections (UTI) are the most common infections in the community, with Escherichia coli constituting the most commonly identified ethiologic agent. Knowledge of the epidemiological reality regarding the susceptibility patterns to various antibiotics used in the treatment of UTI is extremely important, allowing the most appropriate antibiotic choice in the context of empiric therapy. For the treatment of UTI are frequently used antibiotics with a high rate of urinary elimination, including -lactams, quinolones, sulfanamides, fosfomycin and nitrofurantoin, the group of -lactams being one of the most widely used in infections caused by E. coli. However, the emergence of bacteria producing extended-spectrum - lactamases (ESBLs), qAmpCs and/or carbapenemases has been largely compromissing the effectiveness of this antimicrobial group. The genes encoding these resistance mechanisms may be inserted in mobile genetic elements (plasmids) that may also include resistance genes to other groups of antibiotics, further limiting the therapeutic options. In this study we aim to assess the susceptibility patterns to various antibiotics used in the treatment of UTI among 480 E. coli isolates recovered from urine samples of patients who ordered bacteriological examination of urine in a community laboratory; to investigate the occurrence and diversity of genes encoding ESBLs (blaESBL) and/or qAmpC (blaqAmpC) in. isolates identified as presumable ESBL and/or qAmpC producers; and also to evaluate theco-resistance to non--lactam antibiotics among ESBLs and/or qAmpC producers. Bacterial identification and susceptibility to various antibiotics were carried out using the automatic VITEK®2 Systems. Characterization of isolates identified as ESBLs producers included the of double synergism test (DDST) and the identification of blaESBL (blaTEM/blaSHV/blaCTX-M) genes by PCR and sequencing. In isolates identified as possible qAmpC producers, detection and identification blaqAmpC genes was performed by PCR and sequencing. Among the 480 E. coli isolates analysed in this study, 94% were from female patients. The age group from 61 to 75 years old presented higher incidence of UTI in both genders. Isolates were frequently resistant to ampicillin (42.9%), trimethoprimsulfamethoxazole (23.1%), and quinolones, mainly to nalidixic acid (28.6 %). Resistance rates to nitrofurantoin (1.7%) or fosfomycin (2.1%) were lower, and hence both still constitute effective alternatives in the treatment of UTI in the community. None E. coli isolate showed resistance to carbapenems. The ESBLs expression was observed in 3% (14/480) of the E. coli isolates. The blaESBL genes were identified as blaCTX-M (blaCTX-M-14 and blaCTX-M-15) (n=12) or blaSHV (blaSHV-12) (n=2). In four isolates, a phenotype compatible with production qAmpC was detected, and in all of them a blaCMY-2 gene was identified. The co-production of ESBLs and qAmpC (blaSHV-12/blaCMY-2) was also observed (n=1). A multidrug resistance phenotype was found in 1 qAmpC- and in 12 ESBL-producing isolates. This study shows that the spread in the community of E. coli resistant to multiple antibiotics constitutes a disturbing reality, limiting treatment options and contributing to failures in the treatment of UTI, especially in the context of empiric therapy.
Urinary tract infections (UTI) are the most common infections in the community, with Escherichia coli constituting the most commonly identified ethiologic agent. Knowledge of the epidemiological reality regarding the susceptibility patterns to various antibiotics used in the treatment of UTI is extremely important, allowing the most appropriate antibiotic choice in the context of empiric therapy. For the treatment of UTI are frequently used antibiotics with a high rate of urinary elimination, including -lactams, quinolones, sulfanamides, fosfomycin and nitrofurantoin, the group of -lactams being one of the most widely used in infections caused by E. coli. However, the emergence of bacteria producing extended-spectrum - lactamases (ESBLs), qAmpCs and/or carbapenemases has been largely compromissing the effectiveness of this antimicrobial group. The genes encoding these resistance mechanisms may be inserted in mobile genetic elements (plasmids) that may also include resistance genes to other groups of antibiotics, further limiting the therapeutic options. In this study we aim to assess the susceptibility patterns to various antibiotics used in the treatment of UTI among 480 E. coli isolates recovered from urine samples of patients who ordered bacteriological examination of urine in a community laboratory; to investigate the occurrence and diversity of genes encoding ESBLs (blaESBL) and/or qAmpC (blaqAmpC) in. isolates identified as presumable ESBL and/or qAmpC producers; and also to evaluate theco-resistance to non--lactam antibiotics among ESBLs and/or qAmpC producers. Bacterial identification and susceptibility to various antibiotics were carried out using the automatic VITEK®2 Systems. Characterization of isolates identified as ESBLs producers included the of double synergism test (DDST) and the identification of blaESBL (blaTEM/blaSHV/blaCTX-M) genes by PCR and sequencing. In isolates identified as possible qAmpC producers, detection and identification blaqAmpC genes was performed by PCR and sequencing. Among the 480 E. coli isolates analysed in this study, 94% were from female patients. The age group from 61 to 75 years old presented higher incidence of UTI in both genders. Isolates were frequently resistant to ampicillin (42.9%), trimethoprimsulfamethoxazole (23.1%), and quinolones, mainly to nalidixic acid (28.6 %). Resistance rates to nitrofurantoin (1.7%) or fosfomycin (2.1%) were lower, and hence both still constitute effective alternatives in the treatment of UTI in the community. None E. coli isolate showed resistance to carbapenems. The ESBLs expression was observed in 3% (14/480) of the E. coli isolates. The blaESBL genes were identified as blaCTX-M (blaCTX-M-14 and blaCTX-M-15) (n=12) or blaSHV (blaSHV-12) (n=2). In four isolates, a phenotype compatible with production qAmpC was detected, and in all of them a blaCMY-2 gene was identified. The co-production of ESBLs and qAmpC (blaSHV-12/blaCMY-2) was also observed (n=1). A multidrug resistance phenotype was found in 1 qAmpC- and in 12 ESBL-producing isolates. This study shows that the spread in the community of E. coli resistant to multiple antibiotics constitutes a disturbing reality, limiting treatment options and contributing to failures in the treatment of UTI, especially in the context of empiric therapy.