Molecular analysis, biofilm formation, and susceptibility of methicillin-resistant staphylococcus aureus strains causing community- and health care-associated infections in central venous catheters

Abstract INTRODUCTION: The behavior of methicillin-resistant Staphylococcus aureus (MRSA) isolated from central venous catheter-related infection was evaluated to determine its biofilm potential, antimicrobial resistance, and adhesion genes. METHODS: A total of 1,156 central venous catheters (CVC) were evaluated to screen for pathogens. Antimicrobial sensitivity, biofilm formation potential, and molecular analysis of MRSA were examined following standard guidelines. RESULTS: Of the 1,156 samples, 882 (76%) were colonized by bacteria or candida. Among the infected patients, 69% were male and 36% were female with median age of 32 years. Staphylococcus aureus infected 39% (344/882) of CVCs in patients. Of the 59% (208/344) of patients with MRSA, 57% had community acquired MRSA and 43% had hospital acquired MRSA. Linezolid and vancomycin killed 100% of MRSA; resistance levels to fusidic acid, doxycycline, clindamycin, azithromycin, amikacin, trimethoprim-sulfamethoxazole, gentamycin, tobramycin, and ofloxacin were 21%, 42%, 66%, 68%, 72%, 85%, 95%, 97%, and 98% respectively. Strong biofilm was produced by 23% of samples, moderate by 27%, and weak by 50% of MRSA. The presence of adhesion genes, sdrC and sdrD (90%), eno (87%), fnbA (80%), clfA and sdrE (67%), fnbB, sdrD (61%), and cna (51%), in most MRSA samples suggested that the adhesion genes are associated with biofilm synthesis. CONCLUSIONS: The superbug MRSA is a major cause of CVC-related infection. Antibiotic resistance to major classes of antibiotics and biofilm formation potential enhanced superbug MRSA virulence, leading to complicated infection. MRSA causes infection in hospitals, communities, and livestock.

Probable fungemia por Rhodotorula mucilaginosa asociada a catéter venoso central en un paciente pediátrico: presentación de un caso / Probable fungemia by rhodotorula mucilaginosa associated to a central venous catheter in a pediatric pacient: a case report

Las levaduras del género Rhodotorula son patógenos oportunistas emergentes, especialmente en pacientes inmunocomprometidos. Se presenta el caso de un niño de 9 años con sarcoma de Ewing en tratamiento con quimioterapia que cursó con una probable fungemia por Rhodotorula mucilaginosa. Se identificaron varios factores de riesgo tales como la presencia de un catéter venoso central (CVC) y una neoplasia maligna sólida. El diagnóstico se realizó a través de un hemocultivo de una rama del CVC. Nuestra cepa fue identificada como R. Mucilaginosa por morfofisiología y pruebas bioquimicas. El éxito terapeutico se basó en el retiro del CVC y en el tratamiento con anfotericina B desoxicolato como primera alternativa.

Yeasts from Rhodotorula genus are opportunistic pathogen that emerge especially in immunocompromised patients. We report a case of a 9-years-old boy, he developed an Ewing’s sarcoma that was treated with chemotherapy an underwent with problable fungemia by Rhodotorula mucilaginosa. Several risk factors were identified such as presence of a central venous catheter (CVC) and a solid malignant neoplasm. The diagnosis was made by blood culture of a branch of the CVC. Our isolated was identified as R. mucilaginosa by morphofisiology and biochemical test. The therapy did success based on withdrawal of CVC and treatment with amphotericin B deoxycholate as the first alternative.

Lack of effect of cell-wall targeted antibacterials on biofilm formation and antifungal susceptibility of Candida species

The use of central venous catheters (CVC) and broad-spectrum antibacterials are among the main risk factors for the development of candidemia in patients admitted to intensive care units (ICU). It is known that some antibacterials increase the resistance of these yeasts to azole antifungals. Thus, the aim of this research was to determine whether yeast present in CVC colonizations previously exposed to cell-wall targeted antibacterials benefit from a reduction in susceptibility to fluconazole and voriconazole, facilitating their ability to form biofilms. Candida albicans, C. tropicalis, C. glabrata, C. parapsilosis and C. guilhermondii were seeded into antibacterial (cefepime, meropenem, vancomycin, and piperacillin-tazobactam) gradient plates produced in Mueller-Hinton Agar. The susceptibility to fluconazole and voriconazole and the biofilm formation of the yeasts were tested before and after exposure to the antibacterials. None of the antibacterials exerted a significant effect on the in vitro susceptibility of the yeasts to the antifungal agents or on their ability to form biofilms. These results suggest that increased candidemia in ICU patients is not attributable to possible alterations in the yeasts, but is more likely caused by a weakening of the patient's general condition after long exposure to infection.

O uso de cateter venoso central (CVC) e antibióticos de amplo espectro estão entre os principais fatores de risco para o desenvolvimento da candidemia em pacientes internados em unidades de terapia intensiva (UTI). É conhecido que alguns antibióticos aumentam a resistência das leveduras aos antifúngicos azólicos. Assim, o objetivo deste estudo foi avaliar se leveduras presentes em colonização de CVC expostas a antibióticos que atuam em parede celular se beneficiam de uma redução na suscetibilidade ao fluconazol e voriconazol e se obtêm maior capacidade de formar biofilme. Candida albicans, C. tropicalis, C. glabrata,C. parapsilosis e C. guilhermondii foram semeadas em placas de Mueller-Hinton Agar, com gradientes de antibióticos (cefepima, meropenem, vancomicina e piperacilina-tazobactam). A suscetibilidade e a formação de biofilme das leveduras foram testadas antes e após a exposição aos antibióticos. Nenhum dos antibióticos provocou alterações detectáveis in vitro sobre a suscetibilidade das leveduras aos antifúngicos ou à capacidade de formar biofilme. Estes resultados sugerem que o aumento da candidemia na UTI não seria atribuído a possíveis alterações provocadas nas leveduras e sim pelo enfraquecimento da condição geral do paciente após longa exposição à infecção.