Editorial: Microbial Biofilms in Chronic and Recurrent Infections

Biofilm plays a significant role in the pathogenesis of most chronic infections in humans, either tissue-specific or involving medical implants (Lebeaux et al., 2014). Biofilm-associated infections exhibit high resistance to host defenses, often contributing to an excessive or inappropriate inflammatory response leading to further tissue damage and spreading of the infection (Jensen et al., 2010). On the other hand, biofilms are highly tolerant to antimicrobial therapy (Römling and Balsalobre, 2012; Di Domenico et al., 2019). Biofilms can tolerate up to 100–1,000 times higher minimal inhibitory concentration (MIC) than the same bacterial cells in planktonic growth (Macià et al., 2014). Unfortunately, the effective antibiotic MIC in vivo for biofilm eradication may be impossible to reach due to the drugs’ toxicity and side effects, including limitations imposed by renal and/or hepatic functions (Ciofu et al., 2015). However, in vitro experiments showed that an aggressive antibiotic treatment can effectively eradicate biofilm during the initial stage of colonization (Lebeaux et al., 2014; Ciofu et al., 2015). Despite their importance, the early recognition of biofilm-associated infections still represents an unmet need in clinical microbiology. Therefore, the development of novel diagnostic and therapeutic strategies is urgently needed to manage biofilm-associated infections effectively

Identification of metabolic biomarkers to follow wound evolution

International audienc

Virulence et effets des antibiotiques chez les staphylocoques à coagulase négatives responsables de bacteriémies liées au cathéter

International audienc

P090 Molecular epidemiology of methicillin-resistant Staphylococcus aureus in cystic fibrosis: eleven years in the life of a French cystic fibrosis centre

International audienc

Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE): a promising tool to diagnose bacterial infections in diabetic foot ulcers.

International audienceThe diagnosis of diabetic foot infections is difficult due to limitations of conventional culture-based techniques. The objective of this study was to evaluate the contribution of denaturing gradient gel electrophoresis (DGGE) in the microbiological diagnosis of diabetic foot ulcers in comparison to conventional techniques, and also to evaluate the need to perform a biopsy sample for this diagnosis. Twenty diabetic patients (types 1 and 2) with foot ulcers (grades 1-4) were included. After debridement of their wounds, samples were taken in duplicate by surface swabbing and deep-tissue biopsy. The samples were analyzed by conventional culture and by a new molecular biology tool, DGGE technology. Polymerase chain reaction (PCR)-DGGE led to the identification of more bacteria than did conventional cultures (mean: 2.35 vs 0.80, respectively). In 11 cases, the technology detected pathogenic species not isolated by classical cultures. PCR-DGGE also identified significantly more pathogenic species at deep levels compared with species detected at superficial levels (87% vs 58%, respectively; P = 0.03). In 9/20 cases, pathogenic bacteria were detected only in deep samples, revealing the need to perform tissue biopsy sampling. DGGE, achievable in 48h, could be a useful technique for the bacteriological diagnosis of diabetic foot infections. It may help to identify pathogenic bacteria in deeply infected ulcers, thereby contributing to a more appropriate use of antibiotics

Genotyping and antifungal susceptibility testing of Cryptococcus neoformans isolates from Cameroonian HIV-positive adult patients

Cryptococcus neoformans is the most common cause of meningitis amongst adult Africans with HIV/AIDS. The widespread use of fluconazole may lead to the emergence of isolates with reduced susceptibility. We studied C.neoformans isolates from HIV-infected patients with cryptococcal meningitis. Genotyping and antifungal testing were performed to assess the genetic diversity, occurrence of mixed infections and in vitro activity of antifungal agents. Isolates were recovered from cerebrospinal fluid prior to systemic antifungal treatment. Six isolates were studied for each sample (a total of 114 isolates from 19 patients). Serotyping was performed via LAC 1 and CAP 64 gene amplification and genotyping was performed using phage M13 core, (GACA)(4) and (GTG)(5) primers and restriction polymorphism analysis of the URA5 gene. Susceptibilities for amphotericin B, flucytosine, fluconazole, voriconazole and posaconazole were tested by the Sensititre YeastOne (R) method. All strains were identified as C.neoformans var. grubii serotype A. We identified nine major genotypes. Up to two genotypes were identified in the same sample. None of the isolates were resistant to the studied drugs. However, 13 of 114 strains exhibited a reduced susceptibility to fluconazole and 13 of 114 strains exhibited a reduced susceptibility to flucytosine. No correlation was found between the genotype and susceptibility. This study confirms the prevalence of C.neoformans serotype A in Cameroon. Two genotypes may be responsible for a single episode of cryptococcosis. The possibility of mixed infection and diminished susceptibility to fluconazole or flucytosine must be considered for the management of cryptococcosis

Existence of a Colonizing Staphylococcus aureus Strain Isolated in Diabetic Foot Ulcers

Staphylococcus aureus is an opportunistic bacterium capable of causing a wide range of severe diseases when it gains access to underlying tissues. Paradoxically, S. aureus is a common inhabitant of the skin microflora and colonizes the nares and other human mucosa. The purpose of this study was to determine the genetic basis for the differences in the pathogenic versus colonizing potential of S. aureus isolated from diabetic foot ulcers (DFUs). By performing optical map comparisons of a collection of S. aureus strains isolated from DFUs, we brought to light a prophage present in noninfecting bacteria. The phage, namely ROSA-like, was localized in a hotspot region ΦNM2 near the locus isd, the iron surface determinant system. The integrated phage significantly reduces the virulence of the strain and increases the biofilm formation. DFUs seem to be a specific niche of this colonizing strain. The ROSA-like phage represents the first description of a mobile element present mainly in S. aureus isolated from DFUs, which modulates the relationship of the bacteria with its human host. This phage appears to attenuate bacterial virulence and promote colonization