Biofilm is a major virulence determinant in bacterial colonization of chronic skin ulcers independently from the multidrug resistant phenotype

Bacterial biofilm is a major factor in delayed wound healing and high levels of biofilm production have been repeatedly described in multidrug resistant organisms (MDROs). Nevertheless, a quantitative correlation between biofilm production and the profile of antimicrobial drug resistance in delayed wound healing remains to be determined. Microbial identification, antibiotic susceptibility and biofilm production were assessed in 135 clinical isolates from 87 patients. Gram-negative bacteria were the most represented microorganisms (60.8%) with MDROs accounting for 31.8% of the total isolates. Assessment of biofilm production revealed that 80% of the strains were able to form biofilm. A comparable level of biofilm production was found with both MDRO and not-MDRO with no significant differences between groups. All the methicillin-resistant Staphylococcus aureus (MRSA) and 80% of Pseudomonas aeruginosa MDR strains were found as moderate/high biofilm producers. Conversely, less than 17% of Klebsiella pneumoniae extended-spectrum beta-lactamase (ESBL), Escherichia coli-ESBL and Acinetobacter baumannii were moderate/high biofilm producers. Notably, those strains classified as non-biofilm producers, were always associated with biofilm producer bacteria in polymicrobial colonization. This study shows that biofilm producers were present in all chronic skin ulcers, suggesting that biofilm represents a key virulence determinant in promoting bacterial persistence and chronicity of ulcerative lesions independently from the MDRO phenotype

Case report of disseminated nocardiosis during immunosppressive treatment

Infection caused by Nocardia spp. Is unusual and presents with a variety of clinical manifestations in both immunocompromised patients and in immunocompetent hosts.The diagnosis of Nocardia is often difficult, and further hampered by the absence of specific clinical symptoms.A man, 63 years old, caring for about a month from multiple erosions of the oral cavity and Inca intergluteale associated with blisters and erosions scattered in the face, scalp and trunk.The routine laboratory tests, including serological testing for HIV and the determination of circulating CD4 lymphocytes, were negative.The chest X-ray was also negative. Due to the diagnostic suspicion of Pemphigus vulgaris (PV), therapy with methylprednisolone and azathioprine was initiated. After 15 days the patient’s condition worsened and it became necessary hospitalization in intensive care. A CT scan found: pleural empyema, abscess, and paravertebral muscle abscess. The cultural examination of pleural fluid and synovial fluid gave positive results for Nocardia asteroides. On this basis, sulphamethoxazole was administered in association with trimethoprim for 2 months, with a complete remission of the symptoms.At a median follow up of 2 years the patient’s general condition was excellent, without residual signs of infection.The cultured samples from pleural and synovial fluids gave a clear positivity after 5 days of incubation at 37 ° C on blood agar and chocolate agar plates; the colonies showed chalky and thin filaments, slide as branched Gram-positives and appeared partially acid-alcohol resistant by modified Kinyoun staining (1% H2SO4). The presumptive identification of Nocardia spp. was additionally confirmed by biochemical tests for the identification of species with the following results: catalase test positive, oxidase test negative, aesculin hydrolysis, reduction of nitrite to nitrate and urease test positive. Given the low incidence of Nocardia spp. infection, and the non-typical clinical manifestations, microbiological diagnosis of this infection is critical for the selection of an appropriate antibiotic therapy that should be prolonged for several months

Case report of disseminated nocardiosis during immunosppressive treatment

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