S. epidermidis obtained from infected implants forms thicker biofilms than that of healthy volunteers. Hydrogen peroxide, at a concentration of 3% and 5%, and alcohols rapidly eradicate S. epidermidis biofilms, whereas povidone-iodine is less effective.

To investigate the presence of diarrheagenic Escherichia coli in Lambaréné , Gabon, 150 children with diarrhea were screened for enteroaggregative E. coli (EAEC), enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enterohemorrhagic E. coli (EHEC), and enteroinvasive E. coli (EIEC) using polymerase chain reaction and an HEp-2 cell culture techniques. Isolates of EAEC were detected in 57 children, two thirds of them between six months and two years of age, and isolates of ETEC were detected in seven patients. Isolates of EPEC, EHEC, and EIEC were not present in this population. Among the EAEC, the pCVD432 plasmid, a heat stable (ST)−like (ST-like) enterotoxin (EAST), and a plasmid-encoded heat-labile toxin (PET) were detected in 19, 34, and 42 cases, respectively. Detection of pCVD432, EAST, and PET were significantly associated with EAEC identified by the HEp-2 cell assay. Although detected only in 16 patients, the presence of the fimbriae AAF I (aagA) and AAF II (aafA) were more likely to occur in EAEC than in non-EAEC (odds ratio [OR] ‫ס‬ 4.1, 95% confidence interval [CI] ‫ס‬ 0.5−38.6, and OR ‫ס‬ 2.3, 95% CI ‫ס‬ 1.0−5.3, respectively). The EAEC isolates exhibited decreased susceptibility for ampicillin, tetracycline, and trimethoprim.

Implant-related infections are serious complications of trauma and orthopedic surgery and are most difficult to treat. The bacterial biofilms of 34 clinical Staphylococcus sp. isolates (Staphylococcus aureus, n ‫؍‬ 14; coagulase-negative staphylococci, n ‫؍‬ 19) were incubated with daptomycin (DAP; 5, 25, or 100 mg/liter), vancomycin (VAN; 5, 25, or 100 mg/liter), tigecycline (TGC; 1, 5, or 25 mg/liter), fosfomycin (FOM; 100, 250, or 1,000 mg/liter), and cefamandole (FAM; 50, 100, or 500 mg/liter) for 24 h at three different ambient temperatures: 35°C, 40°C, and 45°C. To quantify the reduction of the biomass, the optical density ratio (ODr) of stained biofilms and the number of growing bacteria were determined. Increasing the temperature to 45°C or to 40°C during incubation with FAM, FOM, TGC, VAN, or DAP led to a significant but differential reduction of the thickness of the staphylococcal biofilms compared to that at 35°C (P < 0.05). Growth reduction was enhanced for DAP at 100 mg/liter at 35°C, 40°C, and 45°C (log count reductions, 4, 3.6, and 3.3, respectively; P < 0.05). A growth reduction by 2 log counts was detected for FAM at a concentration of 500 mg/liter at 40°C and 45°C (P ‫؍‬ 0.01). FOM at 1,000 mg/liter reduced the bacterial growth by 1.2 log counts (not significant). The antibacterial activity of antimicrobial agents is significantly but differentially enhanced by increasing the ambient temperature and using high concentrations. Adjuvant hyperthermia may be of value in the treatment of biofilm-associated implant-related infections.

VGS isolated from patients with endocarditis and patients with sepsis and neutropenia form biofilms. Biofilms persist even when exposed to antibiotics at concentrations up to 128 x MIC. Nevertheless, teicoplanin and moxifloxacin reduced the density of the biofilms at concentrations >/=16 x MIC. Thus, testing the effects of antibiotics on biofilms may supply useful information in addition to standard in vitro testing, particularly in diseases where biofilm formation is involved in the pathogenesis.

Background Endocarditis, and prosthetic valve endocarditis in particular, is a serious disease with high morbidity and mortality. We investigate the effects of tigecycline, linezolid and vancomycin on biofilms of viridans group streptococci (VGS) isolated from patients with definite native or prosthetic valve endocarditis. Methods and Results Ten of 20 VGS blood stream isolates from patients with endocarditis formed biofilms in the microtiter plate biofilm model. The minimal inhibitory concentrations (MIC) for tigecycline, linezolid and vancomycin were determined using the microdilution broth method. Biofilms were grown for 24 hours and were incubated with tigecycline, linezolid and vancomycin at increasing concentrations from 1-128x MIC of the isolate being tested. Biofilm thickness was quantified by measuring the optical density (OD) after dyeing it with crystal violet. The incubation of the biofilms with tigecycline, linezolid or vancomycin resulted in a significant reduction of OD compared to the control biofilm without antibiotic (p<0.05). The optical density ratio (Odr) decreased significantly at 2x MIC for tigecycline, and at 8x MIC for linezolid and vancomycin (p<0.05). Although biofilms persisted even at the highest antibiotic concentrations of 128x MIC, bacterial growth was eradicated starting at concentrations of 16x MIC for vancomycin and of 32x MIC for linezolid, but not for tigecycline, up to a concentration of 128x MIC. Conclusions In the present study on viridans streptococci isolated from patients with endocarditis, tigecycline and linezolid reduced the density of the biofilms as effectively as vancomycin. However, linezolid and vancomycin were bactericidal at higher concentrations. Linezolid and vancomycin at very high doses may be useful in the treatment of biofilm-associated diseases caused by VGS infections.