Prevalência e fatores de risco para carreamento nasal e orofaríngeo de Staphylococcus aureus em diabéticos insulino-dependentes no município de Botucatu, SP.
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Data
2019-02-28
Autores
Teixeira, Nathalia Bibiana
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Universidade Estadual Paulista (Unesp)
Resumo
Infecções causadas por Staphylococcus aureus representam um dos principais problemas de saúde pública, com elevadas taxas de morbidade e mortalidade principalmente entre indivíduos com deficiência de sistema imunológico como os diabéticos, em especial aqueles que fazem uso diário de insulina. Além da alta patogenicidade e facilidade de aquisição de resistência aos antimicrobianos, o patógeno tem grande habilidade de colonizar indivíduos de forma assintomática, favorecendo sua disseminação e tornando esses indivíduos fonte de risco para infecções. O estudo teve como objetivo analisar a prevalência e fatores de risco para o carreamento nasal e orofaríngeo, bem como caracterizar o perfil de resistência, virulência e tipagem molecular de S. aureus sensível à meticilina (MSSA) e S. aureus resistente à meticilina (MRSA) isolados de indivíduos diabéticos insulino-dependentes do município de Botucatu, SP. S. aureus foram obtidos da nasofaringe e orofaringe de 312 indivíduos diabéticos insulino-dependentes da comunidade e analisados quanto à presença do gene mecA, genes das enterotoxinas (sea, seb, e sec-1), esfoliatinas A e B (eta e etb), toxina 1 da síndrome do choque tóxico (tst), leucocidina Panton–Valentine (pvl), hemolisinas alfa (hla) e delta (hld) e biofilme (operon icaADBC) através da técnica da reação em cadeia da polimerase (PCR) e a tipagem do SCCmec através de PCRmultiplex. O perfil de sensibilidade à oxacilina, cefoxitina, linezolida, quinupristina/dalfopristina e sulfametoxazol/trimetoprim foi realizada pelo método do disco-difusão e a concentração inibitória mínima (CIM) de vancomicina foi determinada pelo método do E-test. A tipagem molecular dos isolados foi identificado através da técnica de PFGE (Pulsed Field Gel Electrophoresis) e pela técnica de MLST (Multilocus Sequence Typing). Para análise dos fatores de risco foi aplicado um questionário contendo dados demográficos e clínicos que posteriormente foram analisados por modelo de regressão logística para determinar fatores de risco associados ao carreamento de S. aureuse MRSA. A prevalência de colonização global de S. aureus e MRSA foi de 30,4% e 4,8%, respectivamente. Dos 112 isolados de S. aureus, 15 tinham o gene mecA, sendo que 10 carreavam o SCCmec do tipo IV, três carreavam o SCCmec do tipo I e dois isolados carreavam o SCCmec do tipo II. Dos 15 isolados resistentes (MRSA), sete apresentaram sensibilidade à oxacilina e quatro apresentaram sensibilidade à cefoxitina pelo método de disco-difusão. Nenhum dos isolados de S. aureus apresentou resistência à linezolida, quinupristina/dalfopristina e vancomicina, enquanto que um isolado de MSSA, apresentou resistência à sulfametoxazol/trimetoprim. A análise dos fatores de risco para carreamento de S. aureus revelou associação negativa com idade e doença pulmonar, enquanto que úlcera de membros inferiores foi fator de risco. Para carreamento de MRSA apenas o sexo masculino foi associado significativamente como fator de risco na análise multivariada. Quanto à análise do perfil de virulência notou-se alto potencial patogênico tanto de isolados de MSSA quanto de MRSA, com maior prevalência de genes relacionados à produção de biofilme (genes icaA e icaD), enterotoxina A (gene sea) e as hemolisinas alfa (gene hla) e delta (gene hld). Não foram encontrados isolados carreando os genes da esfoliatina B e pvl. A tipagem molecular demonstrou a formação de clusters entre isolados MRSA de pacientes diferentes com presença de ST5 e ST8. Entre os MRSA e MSSA foram identificados isolados carreando o ST398, sugerindo disseminação dessa linhagem entre a população do estudo. Nossos achados reforçam a importância de estudos epidemiológicos de colonização, principalmente em populações de risco aumentado para infecções, como é o caso dos diabéticos, uma vez que além da alta prevalência de MRSA, notou-se também isolados sensíveis virulentos colonizando a mucosa nasal e garganta desses indivíduos, fato que pode contribuir para transmissão, aumento do risco de infecções graves e dificuldade no tratamento.
Infections caused by Staphylococcus aureus is a major public health problem and infections with this microorganism are associated with high morbidity and mortality rates, especially among individuals with immune deficiency disorders such as diabetes and particularly those who take insulin daily. In addition to its high pathogenicity and ability to acquire antimicrobial resistance, asymptomatic infection with this pathogen is common, favoring its dissemination and rendering these individuals a source of infection. The objective of this study was to analyze the prevalence and risk factors for nasal and oropharyngeal carriage, as well as to characterize the resistance profile, virulence, clonal profile and sequence type of methicillin-susceptible (MSSA) and methicillin-resistant S. aureus (MRSA) isolated from insulin-dependent diabetic individuals in the city of Botucatu, SP, Brazil. Staphylococcus aureus was collected from the nasopharynx and oropharynx of 312 community insulin-dependent diabetic individuals. The isolates were analyzed for the presence of the mecA, enterotoxin (sea, seb and sec-1), exfoliatin A and B (eta and etb), toxic shock syndrome toxin 1 (tst), Panton-Valentine leukocidin (pvl), alpha and delta hemolysin (hla and hld), and biofilm (icaADBC operon) genes by the polymerase chain reaction (PCR). SCCmec typing was performed by multiplex PCR. The susceptibility profile against oxacillin, cefoxitin, linezolid, quinupristin/dalfopristin and sulfamethoxazole/trimethoprim was evaluated by the disc diffusion method, and the minimum inhibitory concentration (MIC) for vancomycin was determined by the E-test.The clonal profile of the isolates was characterized by pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) was used to obtain the sequence types of the isolates.The risk factors associated with S. aureus and MRSA carriage were determined by applying a questionnaire containing demographic and clinical data and subsequent logistic regression analysis.The overall prevalence of colonization with S. aureus and MRSA were 31.45% and 4.81%, respectively. Fifteen of the 112 S. aureus isolates carried the mecA gene; SCCmectype IV was identified in 10 isolates, SCCmec type I in three, and SCCmec type II in two. Among the 15 resistant isolates (MRSA), seven were susceptible to oxacillin and four to cefoxitin by the disc diffusion method. None of the S. aureus isolates was resistant to linezolid, quinupristin/dalfopristin or vancomycin, whereas one MSSA isolate was resistant to sulfamethoxazole/trimethoprim. The analysis of risk factors revealed a negative association with age and lung disease, while leg ulcers were a risk factor for S. aureus. For MRSA, only male gender was significantly associated as a risk factor in multivariate analysis. Evaluation of the virulence profile showed a high pathogenic potential of both MSSA and MRSA isolates, with a higher prevalence of biofilm production (icaA and icaD), enterotoxin A (sea), and alpha and delta hemolysin (hla and hld) genes. None of the isolates carried the exfoliatin B or pvl gene. Clonal profile analysis demonstrated the formation of clusters among MRSA isolates from different patients, with the identification of ST5 and ST8. Isolates carrying ST398 were identified among MSSA and MRSA, suggesting dissemination of this lineage in the population studied. Our findings reinforce the importance of epidemiological studies of S. aureus colonization, especially in populations at high risk of infections such as diabetics. In addition to the high prevalence of MRSA, virulent susceptible isolates were found colonizing the nasal mucosa and throat of these individuals, a fact that may contribute to transmission, increase the risk of severe infections, and compromise treatment.
Infections caused by Staphylococcus aureus is a major public health problem and infections with this microorganism are associated with high morbidity and mortality rates, especially among individuals with immune deficiency disorders such as diabetes and particularly those who take insulin daily. In addition to its high pathogenicity and ability to acquire antimicrobial resistance, asymptomatic infection with this pathogen is common, favoring its dissemination and rendering these individuals a source of infection. The objective of this study was to analyze the prevalence and risk factors for nasal and oropharyngeal carriage, as well as to characterize the resistance profile, virulence, clonal profile and sequence type of methicillin-susceptible (MSSA) and methicillin-resistant S. aureus (MRSA) isolated from insulin-dependent diabetic individuals in the city of Botucatu, SP, Brazil. Staphylococcus aureus was collected from the nasopharynx and oropharynx of 312 community insulin-dependent diabetic individuals. The isolates were analyzed for the presence of the mecA, enterotoxin (sea, seb and sec-1), exfoliatin A and B (eta and etb), toxic shock syndrome toxin 1 (tst), Panton-Valentine leukocidin (pvl), alpha and delta hemolysin (hla and hld), and biofilm (icaADBC operon) genes by the polymerase chain reaction (PCR). SCCmec typing was performed by multiplex PCR. The susceptibility profile against oxacillin, cefoxitin, linezolid, quinupristin/dalfopristin and sulfamethoxazole/trimethoprim was evaluated by the disc diffusion method, and the minimum inhibitory concentration (MIC) for vancomycin was determined by the E-test.The clonal profile of the isolates was characterized by pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) was used to obtain the sequence types of the isolates.The risk factors associated with S. aureus and MRSA carriage were determined by applying a questionnaire containing demographic and clinical data and subsequent logistic regression analysis.The overall prevalence of colonization with S. aureus and MRSA were 31.45% and 4.81%, respectively. Fifteen of the 112 S. aureus isolates carried the mecA gene; SCCmectype IV was identified in 10 isolates, SCCmec type I in three, and SCCmec type II in two. Among the 15 resistant isolates (MRSA), seven were susceptible to oxacillin and four to cefoxitin by the disc diffusion method. None of the S. aureus isolates was resistant to linezolid, quinupristin/dalfopristin or vancomycin, whereas one MSSA isolate was resistant to sulfamethoxazole/trimethoprim. The analysis of risk factors revealed a negative association with age and lung disease, while leg ulcers were a risk factor for S. aureus. For MRSA, only male gender was significantly associated as a risk factor in multivariate analysis. Evaluation of the virulence profile showed a high pathogenic potential of both MSSA and MRSA isolates, with a higher prevalence of biofilm production (icaA and icaD), enterotoxin A (sea), and alpha and delta hemolysin (hla and hld) genes. None of the isolates carried the exfoliatin B or pvl gene. Clonal profile analysis demonstrated the formation of clusters among MRSA isolates from different patients, with the identification of ST5 and ST8. Isolates carrying ST398 were identified among MSSA and MRSA, suggesting dissemination of this lineage in the population studied. Our findings reinforce the importance of epidemiological studies of S. aureus colonization, especially in populations at high risk of infections such as diabetics. In addition to the high prevalence of MRSA, virulent susceptible isolates were found colonizing the nasal mucosa and throat of these individuals, a fact that may contribute to transmission, increase the risk of severe infections, and compromise treatment.
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Palavras-chave
Staphylococcus aureus, resistência, Virulência, Diabetes mellitus, Perfil clonal, PFGE, MLST, resistance, virulence, clonal profile