Secondary metabolite from Pseudomonas aeruginosa LV strain exhibits antibacterial activity against Staphylococcus aureus: Metabólito secundário de Pseudomonas aeruginosa cepa LV exibe atividade antibacteriana em Staphylococcus aureus

This study aimed to evaluate the antibacterial activity of the dichloromethane/ethyl acetate fraction (named F4a), obtained from the culture of Pseudomonas aeruginosa LV strain in presence of copper chloride, against planktonic and sessile cells of Staphylococcus aureus, including those presenting multidrug resistance. First, the minimal inhibitory concentrations (MIC) of F4a for twenty-six clinical isolates were determined and the values ranged from 1.56 to 6.25 µg/mL. Minimal bactericidal concentration (MBC) of 3.13 µg/mL was detected in 84.6% of the isolates. The time-kill curve analysis revealed a significant decreased in colony-forming unit counts after 4 h of treatment with the MIC/MBC of F4a. Moreover, the MIC/MBC of the fluopsin C, a copper-containing compound present in F4a, were 1.56/3.13 µg/mL, indicating that this compound seems to be one of the active components related to the antibacterial activity against S. aureus. Images of transmission electron microscopy showed significant ultrastructural alterations in planktonic cells treated with the MIC/MBC of F4a. A significant reduction in the metabolic activity of established biofilms of all S. aureus isolates was observed after treatment with F4a. No hemolytic activity to human erythrocytes was detected for F4a, and the cytotoxic concentration to LLC-MK2 cells was 3.44 µg/mL. In conclusion, F4a exhibited a bactericidal activity against planktonic cells and inhibited the metabolic activity of biofilms of S. aureus. F4a can be promising for the development of new strategies for the treatment of infections caused by S. aureus

A fatal bacteremia caused by hypermucousviscous KPC-2 producing extensively drug-resistant K64-ST11 Klebsiella pneumoniae in Brazil

We report a fatal bacteremia caused by Klebsiella pneumoniae in a 60–70-year-old patient from Brazil. The genomic analysis of three isolates (from blood culture, nasal and anal swabs) showed that the bacteremia was caused by a KPC-2 producing extensively drug-resistant K64-ST11 hypermucousviscous K. pneumoniae (hmKP) harboring several virulence and antimicrobial resistance genes. Although the isolates did not present virulence markers associated with hypervirulent K. pneumoniae (hvKP), they showed invasion and toxicity to epithelial Hep-2 cells; resistance to cell microbicidal mechanisms; and blood and human serum survival, evidencing their pathogenic potential. This study highlights the risk of infection caused by hmKp strains not characterized as hvKP as well as the clinical implications and difficulty of treatment, especially in elderly or immunocompromised patients

A Fatal Bacteremia Caused by Hypermucousviscous KPC-2 Producing Extensively Drug-Resistant K64-ST11 Klebsiella pneumoniae in Brazil

We report a fatal bacteremia caused by Klebsiella pneumoniae in a 60–70-year-old patient from Brazil. The genomic analysis of three isolates (from blood culture, nasal and anal swabs) showed that the bacteremia was caused by a KPC-2 producing extensively drug-resistant K64-ST11 hypermucousviscous K. pneumoniae (hmKP) harboring several virulence and antimicrobial resistance genes. Although the isolates did not present virulence markers associated with hypervirulent K. pneumoniae (hvKP), they showed invasion and toxicity to epithelial Hep-2 cells; resistance to cell microbicidal mechanisms; and blood and human serum survival, evidencing their pathogenic potential. This study highlights the risk of infection caused by hmKp strains not characterized as hvKP as well as the clinical implications and difficulty of treatment, especially in elderly or immunocompromised patients

PROTOCOLO DE ISOLAMENTO DE BACTERIÓFAGOS PARA PSEUDOMONAS AERUGINOSA A PARTIR DE AMOSTRAS DE SECREÇÃO TRAQUEAL

Introdução: As infecções relacionadas à assistência à saúde (IRAS) constituem uma preocupação crescente que exige atenção dos profissionais da saúde, especialmente quando se trata de microrganismos resistentes a múltiplos antimicrobianos (MDR). Pseudomonas aeruginosa, um bacilo Gram-negativo não fermentador, é frequentemente associado a IRAS de alta morbimortalidade e apresenta comumente um perfil MDR. Nesse contexto, a fagoterapia tem emergido como uma alternativa promissora ao uso de antimicrobianos, consistindo no uso de bacteriófagos altamente específicos para o combate às infecções bacterianas. Objetivos: Estabelecer um protocolo de isolamento de bacteriófago de P. aeruginosa isolada de amostra de secreção traqueal. Metodologia: Foram utilizadas amostras de secreção traqueal provenientes do Laboratório de Análises Clínicas da Universidade do Oeste Paulista (UNOESTE), destinadas ao descarte. As amostras clínicas foram diluídas em tampão específico e submetidas à centrifugação. O sobrenadante resultante foi reservado e tratado com clorofórmio para reduzir a presença de células bacterianas, obtendo-se assim um lisado bacteriano que foi mantido a 7°C em geladeira. Os isolados bacterianos, previamente identificados como P. aeruginosa, foram utilizados para cultura do lisado, em meio Luria-Bertani para realização de streak e spot testes. Os plaques formados foram imersos em tampão e armazenados em geladeira para análises moleculares posteriores. Resultados: foi isolado um bacteriófago específico para P. aeruginosa a partir de um total de 10 isolados clínicos testados durante a fase inicial do estudo. Além disso, construiu-se um banco de lisados e isolados a partir de 147 amostras clínicas para análise futura. Conclusão: Esses achados preliminares indicam que a metodologia empregada neste estudo possui um promissor potencial para o isolamento de bacteriófagos específicos para P. aeruginosa. A busca por terapias alternativas ao uso de antimicrobianos é de suma importância para o controle adequado das IRAS e das infecções comunitárias causadas por microrganismos de difícil tratamento. Os resultados obtidos contribuem significativamente para o avanço do conhecimento científico nessa área e podem ter implicações relevantes no desenvolvimento de novas estratégias terapêuticas para o controle das infecções relacionadas à assistência à saúde

Nasal Carriage by Staphylococcus aureus among Healthcare Workers and Students Attending a University Hospital in Southern Brazil: Prevalence, Phenotypic, and Molecular Characteristics

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

Development of a Melting-Curve-Based Multiplex Real-Time PCR Assay for the Simultaneous Detection of Viruses Causing Respiratory Infection

The prompt and accurate identification of the etiological agents of viral respiratory infections is a critical measure in mitigating outbreaks. In this study, we developed and clinically evaluated a novel melting-curve-based multiplex real-time PCR (M-m-qPCR) assay targeting the RNA-dependent RNA polymerase (RdRp) and nucleocapsid phosphoprotein N of SARS-CoV-2, the Matrix protein 2 of the Influenza A virus, the RdRp domain of the L protein from the Human Respiratory Syncytial Virus, and the polyprotein from Rhinovirus B genes. The analytical performance of the M-m-qPCR underwent assessment using in silico analysis and a panel of reference and clinical strains, encompassing viral, bacterial, and fungal pathogens, exhibiting 100% specificity. Moreover, the assay showed a detection limit of 10 copies per reaction for all targeted pathogens using the positive controls. To validate its applicability, the assay was further tested in simulated nasal fluid spiked with the viruses mentioned above, followed by validation on nasopharyngeal swabs collected from 811 individuals. Among them, 13.4% (109/811) tested positive for SARS-CoV-2, and 1.1% (9/811) tested positive for Influenza A. Notably, these results showed 100% concordance with those obtained using a commercial kit. Therefore, the M-m-qPCR exhibits great potential for the routine screening of these respiratory viral pathogens

TCEs 2014 (B)

Termos de Compromisso de Estágio (TCE) e Programa de Atividades de Estágio (PAE) obrigatóris de 30 alunos do Curso de Física (2014)Termos de Compromisso de Estágio (TCE) e Programa de Atividades de Estágio (PAE) obrigatóris de 30 alunos do Curso de Física (2014)Não se aplica

TCEs 2014 (A)

Termos de Compromisso de Estágio (TCE) e Programa de Atividades de Estágio (PAE) obrigatóris de 30 alunos do Curso de Física (2014)Termos de Compromisso de Estágio (TCE) e Programa de Atividades de Estágio (PAE) obrigatórios de 30 alunos do Curso de Física (2014)Não se aplica