RESUMO
Staphylococcus aureus are extremely important microorganisms, either from an epidemiological point of view or as a pathogen, responsible for causing a series of infectious processes, whether simple, restricted to the skin, or invasive infections such as bacteremia. The emergence of Oxacillin Sensitive-Methicillin Resistant S.aureus (OS-MRSA) isolates has imposed difficulties in the treatment of patients with staphylococcal infection, as such isolates can be mistakenly classified as sensitive and lead to failure of the therapy used. Thus, the objective of this study is to evaluate the prevalence, and genotypic and phenotypic characteristics, of OS-MRSA isolates, from bloodstream infections, collected from patients admitted to a hospital in southern Brazil, as well as to evaluate the treatment used. For this, 801 unique isolates of S. aureus, collected from blood cultures, between January 2011 and December 2020 were evaluated. Of these, 96 isolates were classified as sensitive to oxacillin. The isolates were identified and had their sensitivity profile performed by manual and automated methods. The minimum inhibitory concentration for vancomycin, daptomycin, oxacillin, linezolid and teicoplanine was performed by e-test. The mecA, vanA genes, typing of the SCCmec elements, as well as the search for the icaA, tst-1 and pvl virulence genes were performed by PCR. Biofilm formation was performed using the crystal violet technique. The Sequence Type (ST), as well as the Clonal Complex (CC) of the isolates was evaluated by the RTq -PCR. The clinical characteristics of the patients were evaluated through an active search in medical records. After investigating the mecA gene, 27.1% (26/96) of the isolates were considered OS-MRSA, with SCCmec type I being the most prevalent, 46.1% (12/26). Among the evaluated isolates, 41% (9/22) were included in CC5 and ST9. As for virulence, all isolates were positive for the icaA gene and characterized as strong biofilm formers. The pvl gene was found in 92.3% (24/26) of the isolates and the toxic shock syndrome toxin was present in 61.5% of the isolates (16/26). All isolates were negative for the presence of the van A gene. As for the clinical outcome, 73% (19/26) of the patients were discharged from the hospital and 27% (7/26) died. It was possible to observe a high frequency of OS-MRSA isolates causing bloodstream infections. Furthermore, such isolates contain several virulence genes, which may contribute to a worse clinical outcome.
Assuntos
Antibacterianos , Bacteriemia , Proteínas de Bactérias , Genótipo , Staphylococcus aureus Resistente à Meticilina , Testes de Sensibilidade Microbiana , Oxacilina , Proteínas de Ligação às Penicilinas , Infecções Estafilocócicas , Centros de Atenção Terciária , Humanos , Oxacilina/farmacologia , Brasil , Antibacterianos/farmacologia , Infecções Estafilocócicas/microbiologia , Centros de Atenção Terciária/estatística & dados numéricos , Bacteriemia/microbiologia , Proteínas de Bactérias/genética , Proteínas de Ligação às Penicilinas/genética , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Staphylococcus aureus Resistente à Meticilina/classificação , FenótipoRESUMO
BACKGROUND: Staphylococcus aureus is a major cause of a wide diversity of infections in humans, and the expression of Panton-Valentine Leukocidin (PVL) has been associated with severe clinical syndromes. OBJECTIVES: The present study aimed to investigate the prevalence of PVL-encoding genes in S. aureus isolated from clinical samples of inpatients with invasive infections in a teaching hospital in Southern Brazil. Furthermore, phenotypic and genotypic characteristics of bacterial isolates were analyzed. METHODS: A total of 98 S. aureus isolates recovered from different body sites were characterized according to their antimicrobial susceptibility profile, methicillin-resistance and SCCmec typing, genetic relatedness and occurrence of virulence-encoding genes, such as icaA, lukS-PV/lukF-PV, and tst. RESULTS: Sixty-eight (69.4%) isolates were classified as methicillin-resistant, and among them, four (5.9%) did not harbor the mecA gene. The mecA-harboring methicillin-resistant S. aureus (MRSA) isolates were grouped into SCCmec types I (6.3%), II (64.1%), III (6.3%), IV (15.6%), V (4.7%), and VI (1.6%). One isolate (1.6%) was classified as non-typeable (NT). Seventy isolates (71.4%) were classified as multidrug-resistant. The overall prevalence of virulence-encoding genes was as follows: icaA, 99.0%; tst, 27.5%; and lukS-PV/lukF-PV, 50.0%. The presence of tst gene was significantly higher (p < 0.001) in methicillin-susceptible S. aureus (MSSA) compared to MRSA isolates. CONCLUSION: The present study reports a high prevalence of multidrug-resistant S. aureus harboring lukS-PV/lukF-PV and tst genes in invasive infections. The continuous monitoring of the antimicrobial susceptibility profile and virulence of S. aureus is an important measure for the control of infections caused by this bacterium.
Assuntos
Anti-Infecciosos , Staphylococcus aureus Resistente à Meticilina , Infecções Estafilocócicas , Humanos , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus , Prevalência , Meticilina , Brasil/epidemiologia , Pacientes Internados , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/microbiologia , Hospitais Universitários , Fatores de Virulência/genética , Antibacterianos/farmacologia , Testes de Sensibilidade MicrobianaRESUMO
BACKGROUND: Staphylococcus haemolyticus is one of the most frequently coagulasenegative staphylococci isolated from healthcare-associated infections, mainly those related to implanted medical devices. OBJECTIVES: This study aimed to determine the antimicrobial susceptibility profile and biofilm forming capacity of S. haemolyticus isolated from bloodstream infections. METHODS: A total of 40 S. haemolyticus isolates were characterized according to their genetic relatedness by repetitive element sequence based-PCR (REP-PCR), antimicrobial susceptibility profile, SCCmec typing, ability to form biofilm on abiotic surface and occurrence of putative genes related to biofilm formation. RESULTS: One S. haemolyticus was susceptible to all antimicrobials. The other isolates (n=39) were resistant to cefoxitin; and among them 34 (87.2%) harbored the mecA gene into the SCCmec type I (5.9%), type III (29.4%), type IV (5.9%) and type V (20.6%); and 38.2% isolates were designated as NT. Apart from cefoxitin, 94.9% of the isolates were resistant to at least four antimicrobial classes, and 32.5% displayed minimal inhibitory concentration (MIC) values higher than 4.0 µg/mL for vancomycin. All isolates formed biofilm on polystyrene surface and were classified as strong biofilm-producers, except for one isolate. All isolates were negative for icaA gene, and the prevalence of the other genes was as follows: atl, 100%; fbp, 92.5%; aap, 90.0%; and bap, 20.0%. CONCLUSION: This study reports a high prevalence of methicillin-resistant S. haemolyticus displaying decreased susceptibility to vancomycin with the ability to form strong biofilms on abiotic surface. The results support the importance of controlling the adequate use of antimicrobials for the treatment of staphylococcal infections.
Assuntos
Staphylococcus aureus Resistente à Meticilina , Infecções Estafilocócicas , Antibacterianos/farmacologia , Biofilmes , Humanos , Resistência a Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/genética , Testes de Sensibilidade Microbiana , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus haemolyticus/genética , Vancomicina/farmacologiaRESUMO
BACKGROUND: Staphylococcus aureus can asymptomatically colonize the human anterior nares and skin, and nasal colonization by this bacterium represents a potential risk for development of invasive infections. The aim of this study was to determine the prevalence of S. aureus nasal carriage among healthcare workers and students attending a university hospital and to characterize the isolates phenotypically and molecularly. METHODS: A cross-sectional study was performed with 324 volunteers. Cultures from nasal samples were obtained and S. aureus isolates were characterized according to their antimicrobial susceptibility profile and four virulence factors-encoding genes. MRSA isolates were characterized regarding their oxacillin/cefoxitin susceptibility, SCCmec, and REP-PCR types. Potential risks for S. aureus and MRSA carriage were analyzed. RESULTS: Of 324 nasal samples, 42.9% were identified as S. aureus, of which 28.8% were MRSA. S. aureus carriers were significantly higher in males and students (OR = 2.898, 95%CI 1.553-5.410); however, no variables were associated with MRSA carriage. All isolates were susceptible to vancomycin and the highest rate of resistance was observed for penicillin (90.6%). All isolates harbored the coa gene, and 97.8%, the icaA gene; 15.8% and 6.5% were positive for tst and lukS-PV/lukF-PV genes, respectively. Among MRSA isolates, 45% carried the mecA gene but were phenotypically susceptible to oxacillin/cefoxitin; two harbored the tst and none had lukS-PV/lukF-PV genes. All MRSAs were distributed into six SCCmec types and type I (62.5%) was the most frequent. REP-PCR typing identified four main clusters among MRSA isolates. CONCLUSION: High prevalence of healthcare workers and students were identified as nasal carriers of S. aureus exhibiting different antimicrobial resistance profiles, including mecA-positive oxacillin-susceptible S. aureus (OS-MRSA) and the presence of virulence-encoding genes. Both cohorts may represent potential sources for the emergence of a successful S. aureus strain highly adapted to the hospital environment.
RESUMO
mecA-positive oxacillin phenotypically susceptible Staphylococcus aureus (OS-MRSA) is increasingly reported worldwide. This bacterium poses a therapeutic threat, as it can be misidentified as an oxacillin-susceptible organism by phenotypic methods that are routinely used in the majority of clinical microbiology laboratories. Herein, we report the first case of fatal sepsis in a 43-year-old female patient caused by an OS-MRSA SCCmec type IVa/ST1/CC1 in a tertiary hospital in southern Brazil, which highlights the difficulties involved in diagnosing this bacterium. Blood cultures and phenotypic susceptibility tests on admission yielded a penicillin-resistant S. aureus. Although vancomycin therapy was initiated, this antibacterial was replaced by oxacillin, based on the susceptibility result. However, the clinical conditions of the patient deteriorated rapidly evolving to fatal septic shock. Clinical microbiology laboratories should consider the use of additional tests to accurately distinguish between various antimicrobial phenotypes of S. aureus.
Assuntos
Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Oxacilina/farmacologia , Sepse/microbiologia , Infecções Estafilocócicas/microbiologia , Adulto , Brasil , Evolução Fatal , Feminino , Humanos , Oxacilina/uso terapêutico , Sepse/diagnóstico , Sepse/tratamento farmacológico , Infecções Estafilocócicas/diagnóstico , Infecções Estafilocócicas/tratamento farmacológico , Centros de Atenção Terciária , Vancomicina/uso terapêuticoRESUMO
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of human infections worldwide, with major dominant lineage circulating in particular geographical regions. The Brazilian Epidemic Clone (BEC, SCCmec III, ST 239) has been predominant in most Brazilian hospitals. Here, we report the prevalence of MRSA SCCmec type II exhibiting different STs, most of them belonging to CC5 in a tertiary hospital in Southern Brazil.
Assuntos
Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Centros de Atenção Terciária , Antibacterianos/farmacologia , Toxinas Bacterianas , Brasil , DNA Bacteriano , Enterotoxinas , Humanos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Tipagem Molecular , Reação em Cadeia da Polimerase Multiplex , Superantígenos , Vancomicina/farmacologiaRESUMO
Justificativa e Objetivos: Infecções da corrente sanguínea por Staphylococcus aureus constituem uma das principais causas de morbidade e mortalidade em todo mundo. O tratamento de infecções por S. aureus é complexo, em parte, devido à elevada prevalência de resistência aos antimicrobianos. Compreender a epidemiologia e os padrões de resistência deste microrganismo é um ponto crítico para a prescrição empírica adequada de antimicrobianos. Assim, este estudo teve por objetivo avaliar a evolução de resistência antimicrobiana de S. aureus em um período de quinze anos. Métodos: Foram analisados os perfis de sensibilidade para os antimicrobianos ciprofloxacina (5µg); clindamicina (2µg); eritromicina (15µg); gentamicina (10µg); oxacilina (30µg); penicilina (10U); rifampicina (5µg); sulfametoxazol-trimetoprima (23.75/1.25µg) e tetraciclina (30µg) em 720 isolados de S. aureus provenientes de hemoculturas em um hospital terciário do sul do Brasil. Os valores de sensibilidade adotados foram aqueles contidos no CLSI, 2017. Os dados foram obtidos do Sistema de Informação AGTA Healthcare, módulo LABHOS®. Resultados: A frequência média de S. aureus resistente a meticilina foi de 43,74%. Com exceção de penicilina, ocorreu variação significativa da resistência para todos os antimicrobianos no período avaliado (ρ<0,001). Ciprofloxacina (51,14%), eritromicina (44,99%) e clindamicina (39,85%) apresentaram os maiores índices de resistência com tendência de aumento. Surpreendentemente, gentamicina (4%) e sulfametoxazol-trimetoprima (4%) apresentaram queda significativa nos percentuais de resistência. Para vancomicina, do ano 2010 a 2015, observou-se um aumento das concentrações inibitórias mínimas. Conclusão: Embora o índice de resistência tenha aumentado nos quinze anos para a maioria dos antimicrobianos, para sulfametoxazol-trimetoprima e gentamicina ocorreu redução significativa. Este estudo evidenciou, ainda, a emergência do fenótipo S. aureus com resistência intermediária a vancomicina.(AU)
Background and Objectives: Bloodstream infections caused by Staphylococcus aureus are a major cause of morbidity and mortality worldwide. Treatment of S. aureus infections is complex, in part, due to the high prevalence of antimicrobial resistance. Understanding the epidemiology and resistance patterns of this microorganism is a critical point for the proper empirical prescription of antimicrobials. Thus, this study aimed to evaluate the evolution of antimicrobial resistance of S. aureus in a period of fifteen years. Methods: Antimicrobial susceptibility profiles was determined for cefoxitin (30µg), penicillin (10 U), erythromycin (15 µg), clindamycin (2 µg), gentamycin (10 µg),ciprofloxacin (5 µg), sulfamethoxazole-trimethoprim (23.75/1.25 µg), rifampicin (5 µg), and tetracycline (30µg) in 720 S. aureus isolated from blood cultures in a tertiary hospital in southern Brazil were analyzed. Sensiblity values was determined according to Clinical Laboratory Standards Institute (CLSI, 2017).The data were obtained from the AGTA Healthcare Information System, LABHOS® module. Results: The mean frequency of methicillin-resistant S. aureus was 43.74%. Except for penicillin, there was a significant variation of resistance for all antimicrobials in the period evaluated (ρ<0.001). Ciprofloxacin (51.14%), erythromycin (44.99%) and clindamycin (39.85%) had the highest rates of resistance, with tendency to increase. Surprisingly, gentamicina (4%) and sulfamethoxazole-trimethoprim (4%) showed a significant percentage decrease in resistance. For vancomycin, from 2010 to 2015, it was observed an increase in minimum inhibitory concentrations. Conclusion: Although the resistance rate increased in the fifteen years for most antimicrobials, for sulfamethoxazole-trimethoprim and gentamicin a significant reduction occurred, indicating a possible clonal change. This study also evidenced the emergence of S. aureus with intermediate resistance to vancomycin phenotype.(AU)
Justificación y objetivos: Infecciones del flujo sanguíneo por Staphylococcus aureus constituyen una de las principales causas de morbilidad y mortalidad en todo el mundo. El tratamiento de las infecciones por S. aureus es complejo, en parte debido a la elevada prevalencia de resistencia a los antimicrobianos. Comprender la epidemiología y los patrones de resistencia de este microorganismo es un punto crítico para la prescripción empírica adecuada de antimicrobianos. Así, este estudio tuvo por objetivo evaluar la evolución de resistencia antimicrobiana de S. aureus en un período de quince años. Métodos: Se analizaron los perfiles de sensibilidad a los antimicrobianos ciprofloxacino (5µg); clindamicina (2µg); eritromicina (15 µg); gentamicina (10µg); oxacilina (30µg); penicilina (10U); rifampicina (5µg); sulfametoxazol-trimetoprima (23.75 / 1.25 µg) y tetraciclina (30µg) de 720 S. aureus aislados de hemocultivos de un hospital terciario del sur de Brasil. Los valores de sensibilidad adoptados fueron aquellos contenidos en el Clinical Laboratory Standards Institute (CLSI, 2017). Los datos fueron obtenidos del Sistema de Información AGTA Healthcare, módulo LABHOS®. Resultados: La frecuencia media de S. aureus resistente a meticilina fue de 43,74%. Con excepción de la penicilina, hubo variación significativa de la resistencia para todos los antimicrobianos en el período evaluado (ρ<0,001). Ciprofloxacino (51,14%), eritromicina (44,99%) y clindamicina (39,85%) presentaron los mayores índices de resistencia con tendencia de aumento. Sorprendentemente, gentamicina (4%) y sulfametoxazol-trimetoprim (4%) presentaron una caída significativa en los porcentajes de resistencia. Para vancomicina del año 2010 a 2015 se puede evidenciar un aumento de las concentraciones inhibitorias mínimas. Conclusiones: Aunque la resistencia a antimicrobianos aumentó en los quince años para la mayoría de los antimicrobianos, para sulfametoxazol-trimetoprim y gentamicina se produjo una reducción significativa, indicando un posible cambio clonal. Este estudio evidenció, además, la emergencia del fenotipo S. aureus con resistencia intermedia a vancomicina.(AU)