Biofilm Formation on Breast Implant Surfaces by Major Gram-Positive Bacterial Pathogens.

BACKGROUND: Bacterial biofilm on surfaces of mammary implants is a predisposing factor for several outcomes. Because Gram-positive bacteria are potential agents of biomaterial-associated infections (BAIs), their abilities to form biofilm on breast implants should be elucidated. OBJECTIVES: The aim of this study was to evaluate biofilm formation on different mammary prosthesis surfaces by major Gram-positive bacterial pathogens involved in BAIs. METHODS: We initially evaluated biofilm formation on polystyrene plates with and without fibrinogen or collagen for 1 reference strain and 1 clinical isolate of Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes. We also tested the ability of clinical isolates to form biofilm on 4 different implant surfaces: polyurethane foam and smooth, microtextured, and standard textured silicone. Biofilm structure and cell viability were observed by scanning electron microscopy and confocal laser scanning microscopy. RESULTS: All strains showed strong biofilm formation on polystyrene. After fibrinogen or collagen treatment, biofilm formation varied. With fibrinogen, reference strains of S. aureus and S. pyogenes increased biofilm formation (P < 0.05). Reference strains of all species and the clinical isolate of S. pyogenes increased biofilm formation after collagen treatment (P < 0.05). In general, S. aureus showed higher capacity to produce biofilm. Scanning electron microscopy showed that biofilm attached to all surfaces tested, with the presence of extracellular polymeric substances and voids. Viable cells were more frequent for E. faecalis and S. pyogenes. CONCLUSIONS: All species produced biofilm on all prosthesis surfaces and under different conditions. Micrographies indicated thicker bacterial biofilm formation on microtextured and/or standard textured silicone by all species, except E. faecalis.

Corynebacterium ulcerans isolated from an asymptomatic dog kept in an animal shelter in the metropolitan area of Rio de Janeiro, Brazil.

Corynebacterium ulcerans was isolated from nares of one asymptomatic dog kept in an animal shelter in the metropolitan area of Rio de Janeiro, Brazil. The RNA polymerase beta subunit-encoding gene was sequenced to confirm the species identity. C. ulcerans strains producing phospholipase D, but not diphtheria toxin, are able to cause severe disease in humans, such as pneumonia and granulomatous nodules in pulmonary tissues. The infection rate varies really widely by region, probably because of the variations in the reported infection rates. Dogs with unapparent C. ulcerans infections may be considered as potentially capable of infecting other animals and humans, including pet owners. Medical and veterinary staff should be aware that asymptomatic animals can carry C. ulcerans and cooperate in eliminating infections and monitoring animals also in the developing countries.

Corynebacterium diphtheriae as an emerging pathogen in nephrostomy catheter-related infection: evaluation of traits associated with bacterial virulence.

Corynebacterium diphtheriae still represents a global medical challenge, particularly due to the significant number of individuals susceptible to diphtheria and the emergence of non-toxigenic strains as the causative agents of invasive infections. In this study, we characterized the clinical and microbiological features of what we believe to be the first case of C. diphtheriae infection of a percutaneous nephrostomy catheter insertion site in an elderly patient with a fatal bladder cancer. Moreover, we demonstrated the potential role of adherence, biofilm formation and fibrin deposition traits in C. diphtheriae from the catheter-related infection. Non-toxigenic C. diphtheriae isolated from the purulent discharge (named strain BR-CAT5003748) was identified by the API Coryne system (code 1 010 324) and a multiplex PCR for detection of dtxR and tox genes. Strain BR-CAT5003748 showed resistance to oxacillin, ceftazidime and ciprofloxacin. In experiments performed in vitro, the catheter isolate was classified as moderately hydrophobic and as moderately adherent to polystyrene surfaces. Glass provided a more effective surface for biofilm formation than polystyrene. Micro-organisms adhered to (>1.5 x 10(6) c.f.u.) and multiplied on surfaces of polyurethane catheters. Microcolony formation (a hallmark of biofilm formation) and amorphous accretions were observed by scanning electron microscopy on both external and luminal catheter surfaces. Micro-organisms yielded simultaneous expression of localized adherence-like and aggregative-like (LAL/AAL) adherence patterns to HEp-2 cells. Interestingly, the coagulase tube test resulted in the formation of a thin layer of fibrin embedded in rabbit plasma by the non-toxigenic BR-CAT5003748 strain. In conclusion, C. diphtheriae should be recognized as a potential cause of catheter-related infections in at-risk populations such as elderly and cancer patients. LAL/AAL strains may be associated with virulence traits that enable C. diphtheriae to effectively produce biofilms on catheter surfaces. Biofilm formation and fibrin deposition could have contributed to the persistence of C. diphtheriae at the infected insertion site and the obstruction of the nephrostomy catheter.

Aspectos fenotípicos e do potencial patogênico de amostra de Corynebacterium diphtheriae isolada de processo de osteomielite em paciente com neoplasia / Phenotypic aspects and pathogenic potential of Corynebacterium diphtheriae strains isolated from cancer patient with osteomyelitis

Além da difteria permanecer endêmica em diversos países, os clínicos e microbiologistas também devem permanecer atentos ao fato de amostras atoxinogênicas de Corynebacterium diphtheriae causarem infecções invasivas, inclusive em pacientesimunocomprometidos e/ou hospitalizados. Um grupo de microrganismos, incluindo C. diphtheriae, tem sido relacionado com quadros de osteomielite. Em casos de câncer, pode ser favorecido o aparecimento de quadros de osteomielite em decorrência de contaminação por via hematogênica, foco infeccioso ou lesão contígua ao osso. Entretanto, ainda são poucas as investigações relativas ao potencial patogênico de cepas atoxinogênicas de C. diphtheriae. No presente estudo, foi descrito o primeiro caso de isolamento de C.diphtheriae subsp. mitis atoxinogênico e do biotipo não fermentador de sacarose (BR5015) de osteomielite em paciente com câncer.O microrganismo foi capaz de expressar os seguintes fatores de virulência: expressão de perfil de aderência misto dos tipos agregativo e difuso (AA-AD) e elevada (11,13%) capacidade de sobrevivência intracitoplasmática em células epiteliais humanas (HEp-2) além da produção de porfirina e de enzimas catalase, nitrato redutase e DNAse. C. diphtheriae atoxinogênico não deve serconsiderado como mero contaminante, uma vez que pode estar direta ou indiretamente relacionado com o estabelecimento e/ou manutenção de processos infecciosos de origens diversas, incluindo osteomielite.

As well diphtheria remaining endemic in several countries, clinicians and microbiologists must also remain alert to the fact that nontoxigenic samples of Corynebacterium diphtheriae are capable of causing invasive infections, especially in hospitalized and/or immunocompromised patients. Patients with cancer are more susceptible to the appearance of cases of osteomyelitisobtained by hematogenic contamination, an infectious focus or by lesions adjacent to bone. Many microorganisms may be related to cases of osteomyelitis, including C. diphtheriae. However, there are still only a low number of investigations into the pathogenic potential of nontoxigenic strains of C. diphtheriae. The present study is the first documented case of isolation of a nontoxigenic C.diphtheriae subsp. mitis of the non sucrose-fermenting biotype (BR5015 strain) from osteomyelitis in the frontal bone of a patient with adenoid cystic carcinoma. The virulence factors tests were as follows: expression of a mixed adherence patterns of aggregativediffuse(AA-DA) types; high (11.13%) ability to survive within HEp-2 cells; DNase, catalase, nitrate-reductase activities. Therefore, nontoxigenic C. diphtheriae should not be merely regarded as a contaminant, since it can be directly or indirectly related to the establishment and/or maintenance of infectious processes, including osteomyelitis.