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Identificação e caracterização do perfil molecular de resistência de Mycoplasma genitalium aos macrólidos e às fluoroquinolonas numa população da área de Lisboa
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Mycoplasma genitalium é uma bactéria emergente e patogénica, causadora de infeções
sexualmente transmissíveis (IST), cada vez mais relevante na saúde humana. Pode causar
uretrite não gonocócica, cervicite, doença inflamatória pélvica, entre outras
complicações. O crescimento lento e fastidioso de M. genitalium requer um diagnóstico
laboratorial molecular, por testes de amplificação de ácidos nucleicos. Para além disso,
as limitadas opções terapêuticas eficazes e o aumento da emergência de estirpes
resistentes aos antimicrobianos disponíveis colocam este agente de IST na lista de
vigilância da ameaça de resistência antimicrobiana. Por isso, é importante conhecer o
perfil molecular de resistência aos antimicrobianos de M. genitalium, de modo a orientar
uma terapêutica adequada.
Nesta dissertação, efetuou-se a identificação de M. genitalium e caracterizou-se o seu
perfil molecular de resistência aos macrólidos e às fluoroquinolonas numa população da
área de Lisboa constituída por 501 indivíduos. Determinou-se, também, a taxa de
coinfeção com outros agentes de IST.
A identificação de M. genitalium a partir de 543 amostras biológicas efetuou-se por PCR
em tempo real, amplificando o gene da adesina MgPa específico de M. genitalium. O
estudo do perfil molecular de resistência aos antimicrobianos realizou-se por técnica de
PCR em tempo real que deteta a sequência wild-type (wt) do gene 23S rRNA, e por técnica
de PCR convencional seguida de sequenciação para pesquisa de mutações nos genes 23S
rRNA, gyrA e parC.
A taxa de infeção por M. genitalium foi 4,2% (21/501 indivíduos), semelhante entre
homens e mulheres, na população estudada. Observou-se uma taxa de coinfeção de 38%
(13/21 indivíduos), sendo Chlamydia trachomatis a mais frequente. Detetaram-se três
tipos de mutações no gene 23S rRNA associadas à resistência aos macrólidos (A2058G,
A2058T e A2059G), traduzindo-se numa taxa de mutação de 19%. A única mutação
(S83N) detetada no gene parC não apresenta significado clínico conhecido quanto à
contribuição para a resistência às fluoroquinolonas. Não foram detetadas mutações
relevantes no gene gyrA.
Como conclusão, apesar da taxa de infeção por M. genitalium ser baixa, verificou-se uma
taxa de mutações associadas à resistência aos macrólidos significativa na população
estudada. Os resultados obtidos neste estudo sugerem que a implementação de rastreio de
M. genitalium na população geral não deve ser recomendada, mas a pesquisa de mutações
associadas com a resistência aos macrólidos deverá ser realizada em todos os casos
positivos para este agente de IST. A pesquisa de mutações associadas com a resistência
às fluoroquinolonas poderá ser útil em casos de insucesso terapêutico com macrólidos.
A prevenção contra as IST, incluindo M. genitalium, é imprescindível de modo a reduzir
a sua transmissão, resistência antimicrobiana e impacto na saúde humana.
Mycoplasma genitalium is an emergent and pathogenic bacterium that causes sexually transmitted infections (STI), with increasingly relevance in human health. M. genitalium can cause non-gonococcal urethritis, cervicitis, pelvic inflammatory disease, among other complications. The slow and fastidious growth of M. genitalium requires molecular laboratory diagnosis by nucleic acid amplification tests. Furthermore, the limited effective therapeutic options and the increased emergence of resistant strains to the available antimicrobials places this STI agent on the watch list for the threat of antimicrobial resistance. Therefore, it is important to know the antimicrobial resistance molecular profile to guide an adequate therapy. In this dissertation, the identification of M. genitalium and the molecular characterization of the macrolide and fluoroquinolone resistance profile were performed in a population of the Lisbon area consisting of 501 individuals. The rate of coinfection with other agents of STI was also determined. The identification of M. genitalium from 543 biological samples was performed by a real time PCR technique, amplifying the M. genitalium specific MgPa adhesin gene. The study of the antimicrobial resistance molecular profile was carried out using a real-time PCR technique that detects the wild-type (wt) sequence of the 23S rRNA gene, and a conventional PCR technique followed by sequencing for mutation screening in the 23S rRNA, gyrA and parC genes. M. genitalium infection rate was 4.2% (21/501 individuals), similar in both men and women, in the studied population. There was a coinfection rate of 38% (13/21 individuals), the most frequent being Chlamydia trachomatis. Three types of mutations in the 23S rRNA gene associated with macrolide resistance were detected (A2058G, A2058T and A2059G), resulting in a mutation rate of 19%. The only mutation (S83N) detected in the parC gene has no known clinical significance in terms of contribution to fluoroquinolone resistance. No relevant mutations were detected in the gyrA gene. In conclusion, although the M. genitalium infection rate was low, there was a significant rate of mutations associated with macrolide resistance in the studied population. The results obtained in this study suggest that screening for M. genitalium in the general population should not be recommended, but the detection of mutations associated with macrolide resistance should be performed in all positive cases for this STI agent. Looking for mutations associated with fluoroquinolone resistance may be also useful in cases of therapy failure with macrolides. Prevention against STI, including M. genitalium, is imperative in order to reduce transmission, antimicrobial resistance and impact on human health.
Mycoplasma genitalium is an emergent and pathogenic bacterium that causes sexually transmitted infections (STI), with increasingly relevance in human health. M. genitalium can cause non-gonococcal urethritis, cervicitis, pelvic inflammatory disease, among other complications. The slow and fastidious growth of M. genitalium requires molecular laboratory diagnosis by nucleic acid amplification tests. Furthermore, the limited effective therapeutic options and the increased emergence of resistant strains to the available antimicrobials places this STI agent on the watch list for the threat of antimicrobial resistance. Therefore, it is important to know the antimicrobial resistance molecular profile to guide an adequate therapy. In this dissertation, the identification of M. genitalium and the molecular characterization of the macrolide and fluoroquinolone resistance profile were performed in a population of the Lisbon area consisting of 501 individuals. The rate of coinfection with other agents of STI was also determined. The identification of M. genitalium from 543 biological samples was performed by a real time PCR technique, amplifying the M. genitalium specific MgPa adhesin gene. The study of the antimicrobial resistance molecular profile was carried out using a real-time PCR technique that detects the wild-type (wt) sequence of the 23S rRNA gene, and a conventional PCR technique followed by sequencing for mutation screening in the 23S rRNA, gyrA and parC genes. M. genitalium infection rate was 4.2% (21/501 individuals), similar in both men and women, in the studied population. There was a coinfection rate of 38% (13/21 individuals), the most frequent being Chlamydia trachomatis. Three types of mutations in the 23S rRNA gene associated with macrolide resistance were detected (A2058G, A2058T and A2059G), resulting in a mutation rate of 19%. The only mutation (S83N) detected in the parC gene has no known clinical significance in terms of contribution to fluoroquinolone resistance. No relevant mutations were detected in the gyrA gene. In conclusion, although the M. genitalium infection rate was low, there was a significant rate of mutations associated with macrolide resistance in the studied population. The results obtained in this study suggest that screening for M. genitalium in the general population should not be recommended, but the detection of mutations associated with macrolide resistance should be performed in all positive cases for this STI agent. Looking for mutations associated with fluoroquinolone resistance may be also useful in cases of therapy failure with macrolides. Prevention against STI, including M. genitalium, is imperative in order to reduce transmission, antimicrobial resistance and impact on human health.
Descrição
Palavras-chave
Microbiologia médica Infeções sexualmente transmissíveis Mycoplasma genitalium Resistência aos antimicrobianos Testes de amplificação de ácidos nucleicos