Correlation between the in vivo and in vitro antimicrobial properties of commercially available mouthwash preparations.

The effectiveness of six commercially available mouthwashes against common buccal organisms was studied. The minimum inhibitory concentrations (MIC) for two of the studied mouthwashes (Corsodyl and Oraldene) against buccal organisms were determined in Todd Hewitt medium with or without 5% serum. The concentration of the active substance in these two mouthwashes was in excess of the corresponding MIC. When the medium was supplemented with serum, lower MIC values were observed. Kill-time determinations, used at half the concentration of the normal preparation, revealed a rapid lethal effect for all tested mouthwashes. The slowest lethal effect was observed with Fluocaril mouthwash. When mouthwashes were tested in volunteers, an immediate significant fall in salivary bacterial counts was produced by all except Fluocaril. With the latter mouthwash the decrease was significant 2-30 minutes after rinsing. The bacterial levels returned to pre-rinse levels after 30 minutes for Listerine, after 90 minutes for both Oraldene and Mint and after 180 minutes for Corsodyl, Fluocaril and Sansilla mouthwashes. The results indicate that there is a good correlation between in vivo efficacy and in vitro determination of all mouthwash preparations.     

Salivary acetaldehyde increase due to alcohol‐containing mouthwash use: A risk factor for oral cancer

Increasing evidence suggests that acetaldehyde, the first and genotoxic metabolite of ethanol, mediates the carcinogenicity of alcoholic beverages. Ethanol is also contained in a number of ready‐to‐use mouthwashes typically between 5 and 27% vol. An increased risk of oral cancer has been discussed for users of such mouthwashes; however, epidemiological evidence had remained inconclusive. This study is the first to investigate acetaldehyde levels in saliva after use of alcohol‐containing mouthwashes. Ready‐to‐use mouthwashes and mouthrinses (n = 13) were rinsed in the mouth by healthy, nonsmoking volunteers (n = 4) as intended by the manufacturers (20 ml for 30 sec). Saliva was collected at 0.5, 2, 5 and 10 min after mouthwash use and analyzed using headspace gas chromatography. The acetaldehyde content in the saliva was 41 ± 15 μM, range 9–85 μM (0.5 min), 52 ± 14 μM, range 11–105 μM (2 min), 32 ± 7 μM, range 9–67 μM (5 min) and 15 ± 7 μM, range 0–37 μM (10 min). The contents were significantly above endogenous levels and corresponding to concentrations normally found after alcoholic beverage consumption. A twice‐daily use of alcohol‐containing mouthwashes leads to a systemic acetaldehyde exposure of 0.26 μg/kg bodyweight/day on average, which corresponds to a lifetime cancer risk of 3E?6. The margin of exposure was calculated to be 217,604, which would be seen as a low public health concern. However, the local acetaldehyde contents in the saliva are reaching concentrations associated with DNA adduct formation and sister chromatid exchange in vitro, so that concerns for local carcinogenic effects in the oral cavity remain. © 2009 UICC     

In Vitro and In Vivo Antimicrobial Action of Fluphenazine

Abstract

The antipsychotic drug fluphenazine was obtained in a dry powder form and was screened with respect to 482 strains of bacteria, which included 170 Gram-positive and 326 Gram-negative strains. Nutrient agar plates containing increasing concentrations of fluphenazine (0-200 μg/ml) were used for the determination of the minimum inhibitory concentration (MIC) which was demonstrated by inoculating a loopful of an overnight peptone water culture of the organism on nutrient agar plates and determining the MIC against a control. Fluphenazine was detected to possess pronounced action against both Gram-positive and Gram-negative bacteria at 20-100 μg/ml. In the In Vivo studies it was seen that when fluphenazine was used at a concentration of 1.5 μg/g and 3 μg/g mouse body weight both the levels offered significant protection to Swiss strain of white mice when challenged with 50 minimum lethal dose (MLD) of a virulent strain of Salmonella typhimurium 74. The In Vivo data with fluphenazine were highly significant (p <0.001) according to the chi-square test.     

In Vitro Bacterial Adherence to Teicoplanin and Calcium Sulfate-Soaked Bone Cement

Abstract

The aim of this study was to assess In Vitro the improvement in release kinetics for teicoplanin and the inhibition of bacterial adhesion on calcium sulfate-soaked PMMA discs. Calcium sulfate has been used in vivo and shown to be biocompatible, and prevention of bacterial adhesion may be expected with calcium sulfatesoaked polymethylmethacrylate (PMMA). Discs were made by adding teicoplanin and calcium sulfate in powder form to PMMA powder.

The antibiotic concentration eluted from PMMA discs was assayed by agar diffusion assay. Nonadherent bacteria were removed by washing and adherent bacteria were detached by sonication. The suspension including nonadherent bacteria was seeded on sheep blood agar plate and incubated for 24 h at 37°C for the growth of microorganisms.

The teicoplanin released from discs containing calcium sulfate was higher than that released from discs which had not been soaked with calcium sulfate. The count of bacteria adhering to the calcium sulfate-soaked discs was lower than that from the discs without calcium sulfate.

In conclusion, the addition of calcium sulfate to teicoplanin-loaded PMMA bone cement may provide local antibiotic concentrations higher than MIC values due to increased antibiotic release. Furthermore, calcium sulfate was found to be effective in reducing bacterial adherence to treated discs.     

Daptomycin In Vitro Activity Tested Against Gram-Positive Strains Collected from European and Latin American Medical Centers in 2003

Abstract

Daptomycin, a cyclic lipopeptide, was susceptibility tested against clinical bacterial isolates consecutively collected in hospitals located in Europe (4,731 strains) and Latin America (1,007 strains) in 2003 as part of a continuing surveillance program. The bacterial isolates tested were Gram-positive pathogens that included staphylococci, streptococci and enterococci. The isolates were tested for susceptibility using broth microdilution methods (broth with 50 mg/L Ca⁺⁺ for testing daptomycin). All isolates, except two Enterococcus faecium strains from Europe, were inhibited at daptomycin MIC of ≤4 mg/L. In addition, 99.4 and 97.3% of isolates were inhibited at daptomycin MIC of ≤2 and ≤1 mg/L, respectively. Except for one Staphylococcus aureus and one viridans group streptococci from Europe and one coagulase-negative staphylococci from Latin America, all staphylococcal and streptococcal isolates were inhibited by 1 mg/L of daptomycin. Resistance to other compounds (vancomycin, oxacillin, and penicillin) did not influence daptomycin activity. The activity of daptomycin was very similar in both geographic regions evaluated and demonstrated the same MIC distribution as isolates evaluated in studies in the United States. The results of this study showed that daptomycin continues to be very active against clinical isolates of Gram-positive cocci isolated in Europe and Latin America.     

In Vivo Pharmacodynamic Evaluation of Clarithromycin in Comparison to Erythromycin

Abstract

The efficacy of various dosing regimens of clarithromycin and erythromycin against recently isolated Streptococcus pneumoniae strains was determined In Vivo using two animal infection models (mouse peritonitis and thigh infection). For the thigh infection model, mice received a total dose of 4 mg/Kg of either clarithromycin or erythromycin, as a single total dose or divided into 2, 4 or 8 doses/24h. After 24h of therapy S. pneumoniae organisms were killed at 2.06 to 4.03 log₁₀ CFU/thigh by clarithromycin and the one- or two-dose regimens were significantly more effective than the four- or eight-dose regimens. Organism killing following 24h of therapy with erythromycin ranged from 1.13 to 2.31 log₁₀ CFU/thigh, with the one- or two-dose regimens significantly less effective than the four- or eight-dose regimens. In the mouse survival study, the same dose of either clarithromycin or erythromycin was given as a single total dose or divided into two or four doses with dosing intervals of 4 and 2-times the t_1/2 respectively. The results obtained in this model show that there is a significant difference in survival when clarithromycin is administered less frequently (4% deaths for the one-dose regimen in comparison to 40% deaths with the four-dose regimen, P<0.01, Chisquare test). With erythromycin there was a trend for increased survival with the multiple-dose regimen, with significantly higher survival when concentrations exceeding the MIC were maintained for a longer time period. These results indicate that the time during which serum concentrations exceeding the MIC value of the pathogen is an important parameter for efficacy for erythromycin. On the contrary, results with both animal models demonstrate that bacterial killing and survival are significantly higher among clarithromycin-treated mice when the antibiotic is administered less frequently and the highest Cmax/MIC ratio is achieved.     

In vitro postantifungal effect,adhesion traits and haemolysin production of Candida dubliniensis isolates following exposure to 5‐fluorocytosine

The phenomenon of postantifungal effect (PAFE), which is the suppression of candidal growth following brief exposure to antifungal agents, is linked with candidal pathogenicity. Adhesion to buccal epithelial cells (BEC), germ tube (GT) formation and relative cell surface hydrophobicity (CSH) are all adhesion traits of candidal pathogenicity. Ability to produce haemolysin by Candida species is also a determinant of its pathogenicity. There is no information on either the PAFE or its impact on adhesion traits and haemolysin production of oral Candida dubliniensis isolates following exposure to 5‐fluorocytosine (5‐FC). Hence, the focus of this investigation was to research the in vitro PAFE, adhesion to BEC, GT formation, relative CSH and haemolysin production on 20 C. dubliniensis isolates following exposure to 5‐FC. Following obtaining the minimum inhibitory concentration (MIC) of 5‐FC, isolates of C. dubliniensis were exposed to sub‐lethal concentrations (×3 MIC) of 5‐FC for 1 h. After this brief exposure, the antimycotic was removed and PAFE, adhesion to BEC, GT formation, relative CSH and haemolysin production was determined by formerly described in vitro methods. MIC (μg/ml) of C. dubliniensis isolates to 5‐FC ranged from 0.002 to 0.125. The mean PAFE (hours) elicited by 5‐FC on C. dubliniensis isolates was approximately 1 h. Exposure to 5‐FC suppressed the ability of C. dubliniensis isolates to adhere BEC, GT formation, relative CSH and haemolysin activity by a mean percentage reduction in 50.98%, 29.51%, 36.79% and 12.75% (P < 0.001 for all) respectively. Therefore, brief exposure of C. dubliniensis isolates to 5‐FC appears to exert an antifungal effect by subduing its growth, adhesion traits as well as haemolysin production.     

In Vitro Activity of Lomefloxacin (SC-47111) Against Enterobacteriaceae,Enterococci and Staphylococci

Summary

The activity of lomefloxacin, a new difluorinated quinolone, was tested against 190 Enterobacteriaceae strains (belonging to 23 different species), 70 enterococci and 70 staphylococci. As regards Enterobacteriaceae, the activity of lomefloxacin was the same as that of norfloxacin in 9 out of the 23 species tested, and only slightly lower in further 8 species. Minimum inhibitory concentrations (MIC) values for 90% of strains were 0.5 μg/ml in 2 species, 0.25 μg/ml in 6, 0.125 μg/ml in 4, and lower than 0.125 μg/ml in 8. Slightly higher values were obtained for Serratia marcescens (2 μg/ml), whilst, as already reported for the other new quinolones, the susceptibility of the Providencia genus was very poor, with MIC values up to 128 μg/ml for the vast majority of strains. Lomefloxacin proved bactericidal at the MIC in all the Enterobacteriaceae strains tested but 20. In the latter strains, however, bactericidal activity could be appreciated at values slightly exceeding MIC. As regards enterococci, the MIC for 90% of strains was 32 μg/ml. Minimum bactericidal concentration (MBC) was the same as the MIC for 78% of the strains tested and was only twofold higher in all the others. The new drug was also active against staphylococci having an MIC50 and MIC₉₀ of 0.5 and 2 μg/ml, respectively. It was bactericidal at the MIC for 62% of the strains and at twofold the MIC for all the others.     

Determination of the Susceptibility In Vitro of 54 Isolates of Mycobacterium fortuitum against Three Fluoroquinolones Using Two Methods

Abstract

The In Vitro susceptibility to ofloxacin, norfloxacin and ciprofloxacin or 54 Mycobacterium fortuitum isolates originating from clinical samples (7) of patients attending the Hospital Universitario de Canarias and Hospital del Tórax, and from environmental (47) sources, were determined. For this, two methods were used: dilution in agar with Middlebrook 7H10 Agar as a base medium culture, and broth microdilution, with Mueller-Hinton Broth without supplement.

The different isolates under study revealed a uniform susceptibility by both methods against ciprofloxacin.

100% inhibition was obtained from a Minimum Inhibitory Concentration (MIC) of 0.25 μg/ml, and 2 μg/ml of ciprofloxacin, for broth microdilution and dilution in agar, respectively.

For ofloxacin and norfloxacin, all the isolates were inhibited at an MIC of 0.5 μ/ml, by the broth microdilution method, which contrasted sharply with an MIC of 32 μ/ml, in the case of dilution in agar.

In this study, we have observed the existence of differences in the In Vitro susceptibility of the isolates of M. fortuitum against the three fluoroquinolones assayed, mainly for ofloxacin and norfloxacin, by both methods. We, therefore, consider it necessary to establish a standardized, reproducible assay method, for the study of sensitivity to atypical mycobacteria.     

In Vitro Activity of Cefpirome (HR 810) against Enterococci and Staphylococci

Summary

The inhibitory activity of cefpirome (HR 810), a new cephalosporin derivative for parenteral use, was tested by agar dilution methods against Enterococcus faecatis (100 strains), Staphylococcus aureus (40 strains) and coagulase-negative staphylococcal species (60 strains) in comparison with other beta-lac ta m antibiotics.

For E. faecalls, the cefpirome minimum inhibitory concentration (MIC) range was 2-128 μg/ml, with an MIC,, of 8 μg/ml, and an MIC₉₀, of 64 μg/ml. The optimal bactericidal activity against strains with MICs of ≤ 8 μg/ml occurred at 2-4 times the MIC, and the reduction in the initial inoculum was 99.9-99.7% after 24 h incubation at these concentrations.

Mec gene-negative staphylococci (both S. aureus and coagulase- negative species) had cefpirome MICs of 0.25-2 μg/ml (MIC₅₀ 0.5 μg/ml, MIC₉₀ 1 μg/ml). Mec gene-positive strains had MICs of 0.5-128 μg/ml (MIC₅₀ 2 μg/ml, MIC₉₀ 32 μg/ml). Strains with borderline resistance to oxacillin which did not harbor the mec gene and which were susceptible to cefpirome maintained their susceptibility even when high-density inocula were used and after several passages in media containing the antibiotic.

These studies present some potential advantages of cefpirome over other cephalosporins in the inhibitory activity against Gram-positive cocci.     

Antiseptic effect of a novel alcohol-free mouthwash: a convenient prophylactic alternative for high-risk patients

We developed an efficacious and non-irritant mouthwash that is alcohol-free and that has a low concentration of chlorhexidine, in order to be used for preventing oral cavity infections in immunocompromised and cancer patients. The novel mouthwash solution was tested for its antimicrobial efficacy against both free floating (planktonic) and the biofilm forms of Candida albicans. The solution was also tested against Klebsiella pneumoniae, Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus (MRSA), using a modification of a previously published method. The activity of the novel mouthwash was also compared with that of three commercially available mouthwashes. The experimental mouthwash showed efficacy against C. albicans, both in free-floating form and in biofilm. With higher concentration of chlorhexidine, the solution was also efficacious in inhibiting the growth of K. pneumoniae, P. aeruginosa, and MRSA. The antiseptic activity of the alcohol-free mouthwash against other bacterial organisms and C. albicans was comparable to other commercially available alcohol-based mouthwash solutions. A novel alcohol-free mouthwash solution, that has low concentration of chlorhexidine, showed antiseptic effect against planktonic and biofilm forms of C. albicans and against K. pneumoniae, P. aeruginosa, and MRSA.     

In Vitro Activity of Cefdinir against Respiratory Pathogens Isolated in Sicily with Reference to Beta-Lactamase Production

Abstract

The In Vitro activity of cefdinir (CI-983, FK-482), an orally absorbed aminothiazolyl cephalosporin, was evaluated against all 287 strains of Haemophilus influenzae, Haemophilus parainfluenzae, Moraxella catarrhalis, Streptococcus pneumoniae and Streptococcus pyogenes in comparison with cefaclor, cefuroxime, amoxicillin, amoxicillin-clavulanic acid, erythromycin and cotrimoxazole.

The bactericidal activity of cefdinir, cotrimoxazole, amoxicillin-clavulanic acid and erythromycin was determined against H. influenzae, M. catarrhalis and S. pneumoniae. With the exception of one beta-lactamase negative ampicillin-resistant strain of H. influenzae (resistant to all antibiotics tested), no resistance to cefdinir was observed (MIC≤1 mg/l). Cefdinir was active against H. influenzae, H. parainfluenzae and M. catarrhalis regardless of whether or not they produced beta-lactamase. In general, the inhibitory concentrations of cefdinir against H. influenzae, H. parainfluenzae and M. catarrhalis were similar to those of amoxicillin/clavulanic acid, one or two dilutions lower than those of cefuroxime and four dilu tions lower than those of cefaclor and cotrimoxazole. Against S. pneumoniae and S. pyogenes cefdinir had the same activity as cefuroxime and amoxicillin but was more effective than the other antibiotics tested.

Kinetic studies showed that cefdinir was rapidly bactericidal at concentrations 2 and 4 times the minimum inhibitory concentration (MIC): a reduction of 99.9% in CFU values was generally observed after 6-8 h.     

Antimicrobial Action and Pharmacokinetics/Pharmacodynamics: The Use of AUIC to Improve Efficacy and Avoid Resistance

Abstract

In in-vitro and in animal models, antibiotics show good relationships between concentration and response, when response is quantified as the rate of bacterial eradication. The strength of these in-vitro relationships promises their utility for dosage regimen design and predictable cure of human infections. Resistance is also predictable from these parameters, fostering a rational means of using dosing adjustments to avoid or minimize the development of resistant organisms.

Newly developed computerized methods for the quantitation of susceptibility allow testing of integrated kinetic-susceptibility models in patients. Our attention has focused recently on fluoroquinolones, since they are relatively nontoxic and provide the necessary range of dosage needed to elucidate correlations between concentration and response in the Intensive Care Unit patient. Studies conducted in patients with nosocomial Gram-negative pneumonia reveal good correlations between bacterial eradication and integration of concentration with bacterial susceptibility. In patients, the best correlation parameters are time over MIC, and the ratio of 24-hour AUC to MIC (AUIC).

Patients with serious infections like nosocomial pneumonia require bactericidal antimicrobial activity. Studies in our laboratory demonstrate that the minimum effective antimicrobial action is an area under the inhibitory titer (AUIC) of 125, where AUIC is calculated as the 24-hour serum AUC divided by the MIC of the pathogen. This target AUIC may be achieved with either a single antibiotic or it can be the sum of AUIC values of two or more antibiotics. There is considerable variability in the actual AUIC value for patients when antibiotics are given in their usually recommended dosages. Examples of this variance will be provided using aminoglycosides, fluoroquinolones, beta-lactams, macrolides and vancomycin. The achievement of minimally effective antibiotic action, consisting of an AUIC of at least 125, is associated with bacterial eradication in about 7 days for beta-lactams and quinolones. When AUIC is increased to 250, the quinolone ciprofloxacin (which displays in vivo concentration dependent bacterial killing) can eliminate the bacterial pathogen in 1-2 days. Beta lactams, even when dosed to an AUIC of 250, often require longer treatment duration to eliminate the bacterial pathogen, because the in vivo bacterial killing rate is slower with beta-lactams than with the quinolones. This remains true even at AUIC values of 250 for both compounds, which is theoretically identical dosing.

Antibiotic activity indices allow clinicians to evaluate individualized patient regimens. Furthermore, antibiotic activity is a predictable clinical endpoint with predictable clinical outcome. This value is also highly predictive of the development of bacterial resistance. Antimicrobial regimens that do not achieve an AUIC of at least 125 cannot prevent the selective pressure that leads to overgrowth of resistant bacterial sub-populations. Indeed, there is considerable anxiety that conventional respiratory tract infection management strategies, which prescribe antibacterial dosages that may attain AUIC values below 125, are contributing to the pandemic rise in bacterial resistance levels.     

In vitro effects of sulbactam combinations with different antibiotic groups against clinical Acinetobacter baumannii isolates

Abstract

Treatment of multidrug resistant (MDR) Acinetobacter baumannii infections causes some problems as a result of possessing various antibacterial resistance mechanisms against available antibiotics. Combination of antibiotics, acting by different mechanisms, is used for the treatment of MDR bacterial infections. It is an important factor to determine synergy or antagonism between agents in the combination for the constitution of effective therapy. The study aimed to determine in vitro interactions interpreted according to calculated fractional inhibitory concentration (FIC) index between sulbactam and ceftazidime, ceftriaxone, cefepime, ciprofloxacin, gentamicin, meropenem, tigecycline, and colistin. Ten clinical isolates of A. baumannii were tested for determination of synergistic effects of sulbactam with different antimicrobial combinations. Minimal inhibitory concentration (MIC) values of both sulbactam and combined antibiotics decreased 2- to 128-fold. Synergy and partial synergy were determined in combination of sulbactam with ceftazidime and gentamicin (FIC index: ≤0·5 or >0·5 to <1) and MIC values of both ceftazidime and gentamicin for five isolates fell down below the susceptibility break point. Similarly, MIC value of ciprofloxacin for six ciprofloxacin resistant isolates was determined as below the susceptibility break point in combination. However, all isolates were susceptible to colistin and tigecycline, MIC values of both were decreased in combination with sulbactam. Although synergistic and partial synergistic effects were observed in the combination of sulbactam and ceftriaxone, all isolates remained resistant to ceftriaxone. The effect of cefepime–sulbactam combination was synergy in five, partial synergy in one and indifferent in four isolates. Meropenem and sulbactam showed a partial synergistic effect (FIC index: >0·5 to <1) in three, an additive effect (FIC index: 1) in one and an indifferent effect (FIC index: >1–2) in six isolates. Antagonism was not determined in any combination for clinical A. baumannii isolates in the study. In conclusion, sulbactam is a good candidate for combination treatment regimes for MDR A. baumannii infections.     

Evaluation of Ciprofloxacin’s Activity against Recent Clinical Isolates

Summary

The in vitro antibacterial activity of ciprofloxacin, a new quinoline carboxylic acid, was tested against 1671 recendy clinically isolated bacterial strains, by measuring the minimum inhibitory concentrations (MIC). Comparisons were made with other quinolones: nalidixic acid, norfloxacin, and other drugs: piperacillin, cefoxitin, cefotetan, ceftazidime, tobramycin, rifampin, tetracycline, chloramphenicol.

Ciprofloxacin was very active against the tested species and was the most active drug against all the bacterial strains, with a geometric mean, a MIC₅₀ and MIC₉₀ of 0.27, 0.12 and 2 μg/ml, respectively.     

Determination of the In Vitro Susceptibility of 220 Mycobacterium fortuitum Isolates to Ten Antimicrobial Agents

Abstract

The authors investigated the In Vitro susceptibility to antimicrobial agents of 220 Mycobacterium fortuitum isolates originating from clinical samples (14) of patients attending the Hospital Universitario de Canarias and Hospital del Tórax, and from environmental sources (206): 3 from sea water, 10 from the water supply and 193 from sewage. The Minimum Inhibitory Concentration (MIC) was calculated using the broth microdilution method with Mueller-Hinton Broth without supplement. Amikacin was the most efficacious antimicrobial agent against all the isolates of M. fortuitum with an MIC which was considerably lower than its critical concentration. The good results achieved with amikacin In Vitro are confirmed by those obtained in vivo, with patients infected with M. fortuitum. No significant difference was found in the efficacy of amikacin and ofloxacin against all the isolates assayed.     

The effectiveness of commonly used mouthwashes for the prevention of chemotherapy-induced oral mucositis: a systematic review

Daily chlorhexidine mouthwash is often recommended for preventing chemotherapy-induced oral mucositis. Povidone-iodine, NaCl 0.9%, water salt soda solution and chamomile mouthwash are also recommended. However, the effectiveness of these mouthwashes is unclear. Therefore, we performed a systematic review to assess the effectiveness of mouthwashes in preventing and ameliorating chemotherapy-induced oral mucositis. Based on study quality, three out of five randomized controlled trials were included in a meta-analysis. The results failed to detect any beneficial effects of chlorhexidine as compared with sterile water, or NaCl 0.9%. Patients complained about negative side-effects of chlorhexidine, including teeth discoloration and alteration of taste in two of the five studies on chlorhexidine. The severity of oral mucositis was shown to be reduced by 30% using a povidone-iodine mouthwash as compared with sterile water in a single randomized controlled trial. These results do not support the use of chlorhexidine mouthwash to prevent oral mucositis.     

Periodontal disease and mouthwash use are risk factors for head and neck squamous cell carcinoma

Purpose

The purpose of this study was to examine associations between oral hygiene, including history of periodontal disease and mouthwash use, and risk of head and neck squamous cell carcinoma (HNSCC).

Methods

We measured history of oral hygiene and dental care on 513 HNSCC cases and 567 controls from a population-based study of HNSCC. Logistic regression was used to estimate odds ratios (ORs) and 95 % confidence intervals (95 % CI).

Results

Periodontal disease was associated with a slightly elevated risk of HNSCC (OR = 1.09, 95 % CI: 1.02, 1.16). Using any type of mouthwash at least once per day was associated with increased risk compared to never using mouthwash (OR = 1.11, 95 % CI: 1.02, 1.20). HNSCC was associated with frequent use of non-alcoholic mouthwash compared to using any kind of mouthwash rarely or never (OR = 1.24, 95 % CI: 1.05, 1.47).

Conclusions

Our results support an association between periodontal disease and HNSCC. Our data suggest that mouthwash use is associated with HNSCC, but we noted no difference between the effects of alcohol-containing and non-alcoholic mouthwashes.     

Antimicrobial susceptibility and the in vitro postantibiotic effects of vancomycin and ciprofloxacin against Bacillus cereus isolates

Background: Vancomycin and ciprofloxacin were often used in the therapy of infections associated with Bacillus cereus.

Methods: Four B. cereus food and clinical isolates were chosen for determination of time–kill curves and postantibiotic effects (PAE) of ciprofloxacin and vancomycin.

Results: According to the minimum inhibition concentration (MIC), breakpoints defined by CLSI for Staphylococcus spp. were all four strains intermediate for vancomycin (MIC?=?4?μg/ml) and sensitive to ciprofloxacin (MIC?=?0.2?μg/ml) except the strain Bc63 resistant to the last antimicrobial (MIC?=?1.6?μg/ml). The lowest CFU values of tested strains were reached after 3–5?hours of exposure to 4?× MIC of vancomycin, and after 6–7?hours exposure to 10?× MIC of ciprofloxacin. The maximum reduction of the CFU in the presence of vancomycin and ciprofloxacin was about 2.46 log₁₀ and 2.48 log₁₀, respectively. The average duration of the PAE of vancomycin and ciprofloxacin was 0.94 and 1.60?hours, respectively. The statistically significant differences between PAEs induced with 3?× MIC, 4?× MIC and 8?× MIC of vancomycin were observed (P?Conclusions: The differences in PAE duration were strain and antimicrobial dependent.     

In vitro effect of subminimal inhibitory concentrations of antibiotics on the biofilm formation ability of Acinetobacter baumannii clinical isolates

The ability of A cinetobacter baumannii strains to form biofilm is one of the most important virulence factor which enables bacterial survival in a harsh environment and decreases antibiotic concentration as well. Subminimal inhibitory concentrations (subMICs) of antibiotics may change bacterial ultrastructure or have an influence on some different molecular mechanisms resulting in morphological or physiological changes in bacteria itself. The aim of this study was to determine effects of 1/2, 1/4, 1/8 and 1/16 minimal inhibitory concentrationsof imipenem, ampicillin-sulbactam, azithromycin, rifampicin and colistin on biofilm formation ability of 22 biofilm non-producing and 46 biofilm producing A. baumannii strains (30 weak producing strains and 16 moderate producing strains). Results of this study indicate that 1/2–1/16 MICs of imipenem, azithromycin, and rifampicin can reduce bacterial biofilm formation ability in moderate producing strains (p < 0.05), whereas 1/16 MIC of imipenem and 1/4–1/8 MICs of rifampicin reduce the biofilm formation in weak producing strains (p < 0.05). Statisticaly significant effect was detected among biofilm non-producing strains after their exposure to 1/16 MIC of azithromycin (p = 0.039). SubMICs of ampicillin-sulbactam and colistin did not have any significant effect on biofilm formation among tested A. baumannii strains.