Microbial biofilm correlates with an increased antibiotic tolerance and poor therapeutic outcome in infective endocarditis

Background

Infective endocarditis (IE) is associated with high rates of mortality. Prolonged treatments with high-dose intravenous antibiotics often fail to eradicate the infection, frequently leading to high-risk surgical intervention. By providing a mechanism of antibiotic tolerance, which escapes conventional antibiotic susceptibility profiling, microbial biofilm represents a key diagnostic and therapeutic challenge for clinicians. This study aims at assessing a rapid biofilm identification assay and a targeted antimicrobial susceptibility profile of biofilm-growing bacteria in patients with IE, which were unresponsive to antibiotic therapy.

Results

Staphylococcus aureus was the most common isolate (50%), followed by Enterococcus faecalis (25%) and Streptococcus gallolyticus (25%). All microbial isolates were found to be capable of producing large, structured biofilms in vitro. As expected, antibiotic treatment either administered on the basis of antibiogram or chosen empirically among those considered first-line antibiotics for IE, including ceftriaxone, daptomycin, tigecycline and vancomycin, was not effective at eradicating biofilm-growing bacteria. Conversely, antimicrobial susceptibility profile of biofilm-growing bacteria indicated that teicoplanin, oxacillin and fusidic acid were most effective against S. aureus biofilm, while ampicillin was the most active against S. gallolyticus and E. faecalis biofilm, respectively.

Conclusions

This study indicates that biofilm-producing bacteria, from surgically treated IE, display a high tolerance to antibiotics, which is undetected by conventional antibiograms. The rapid identification and antimicrobial tolerance profiling of biofilm-growing bacteria in IE can provide key information for both antimicrobial therapy and prevention strategies.

Oral cancer associated with chronic mechanical irritation of the oral mucosa

Background

Most of the studies dealing with Chronic Mechanical Irritation (CMI) and Oral Cancer (OC) only considered prosthetic and dental variables separately, and CMI functional factors are not registered. Thus, the aim of this study was to assess OC risk in individuals with dental, prosthetic and functional CMI. Also, we examined CMI presence in relation to tumor size.

Material and Methods

A case-control study was carried out from 2009 to 2013. Study group were squamous cell carcinoma cases; control group was patients seeking dental treatment in the same institution.

Results

153 patients were studied (Study group n=53, Control group n=100). CMI reproducibility displayed a correlation coefficient of 1 (p<0.0001). Bivariate analysis showed statistically significant associations for all variables (age, gender, tobacco and alcohol consumption and CMI). Multivariate analysis exhibited statistical significance for age, alcohol, and CMI, but not for gender or tobacco. Relationship of CMI with tumor size showed no statistically significant differences.

Conclusions

CMI could be regarded as a risk factor for oral cancer. In individuals with other OC risk factors, proper treatment of the mechanical injuring factors (dental, prosthetic and functional) could be an important measure to reduce the risk of oral cancer.

Key words:Oral cancer, risk factors, chronic mechanical irritation, tumor size, case-control study.

[Human papillomavirus detection in oral cancer lesions in the city of Córdoba]

Oral cancer is a process that involves different etiological factors and mechanisms in the light of current view of viral cocarcinogenesis. Evidence from histology and DNA hybridization studies suggests that HPV is engaged in oral carcinogenesis. The Pathology Laboratory of the Dentistry School, National University of Córdoba, admits approximately 20% of all patients with cancerous lesions in this city. In the January 1992-December 1997 lapse, we examined 1950 biopsies with oral lesions, 4.77% (93/1950) of which were malignant neoplasms, 79.57% (74/93) were oral carcinomas. Thirty-three oral carcinomas (44.6%; 33/74) were selected at random and included in this study, 33 cells smears of normal oral mucosa of controls individuals were included. They were analyzed by conventional light microscopy and an in situ hybridization technique for the detection of HPV. Data were analyzed with chi square test. The prevalence of HPV among the 33 cancer samples studied was 27.27%, 9/33 tested positive for HPV in low stringent conditions. Only one was positive in high stringent condition for HPV16, a verrugous carcinoma. No HPV-DNA was detected in cells smears of controls. Among the HPV positive, 3/9 (33.33%) were squamous carcinomas and 5/9 (55.56%) were verrugous carcinomas. Only one was a melanoma. Verrugous carcinoma was the carcinoma most associated with the HPV infection (x2 = 20.5; 95% level of confidence). This would indicate a major role of HPV in the pathogenesis of verrucous carcinomas. The viral prevalence found in cancerous lesions reinforces the concept of heterogenic natures of oral cancer. HPV is a circumstance that increase the probability of malignancy, and when reducing, diminish the frequency of cancer.