p-mTOR, p-ERK and PTEN Expression in Tumor Biopsies and Organoids as Predictive Biomarkers for Patients with HPV Negative Head and Neck Cancer.

BACKGROUND: Survival rates of head and neck squamous cell carcinoma (HNSCC) have only marginally improved in the last decades. Hence there is a need for predictive biomarkers for long-time survival that can help to guide treatment decisions and might lead to the development of new therapies. The phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR signaling pathway is the most frequently altered pathway in HNSCC, genes are often mutated, amplificated and overexpressed causing aberrant signaling affecting cell growth and differentiation. Numerous genetic alterations of upstream and downstream factors have currently been clarified. However, their predictive value has yet to be established. Therefore we assess the predictive value of p-mTOR, p-ERK and PTEN expression. METHODS: Tissue microarrays (TMA's) of HPV-negative patients with oropharyngeal (n = 48), hypopharyngeal (n = 16) or laryngeal (n = 13) SCC, treated with primary chemoradiation (cisplatin/carboplatin/cetuximab and radiotherapy), were histologically stained for p-mTOR, PTEN and p-ERK. Expression was correlated to overall survival (OS), disease free survival (DFS) and locoregional control (LRC). Also p-mTOR was histologically stained in a separate cohort of HNSCC organoids (n = 8) and correlated to mTOR-inhibitor everolimus response. RESULTS: High p-mTOR expression correlated significantly with worse OS in multivariate analysis in the whole patient cohort [Hazar Ratio (HR) 1.06, 95%CI 1.01-1.11, p = 0.03] and in the cisplatin/carboplatin group with both worse OS (HR 1.09, 95%CI 1.02-1.16, p = 0.02) and DFS (HR 1.06, 95%CI 1.00-1.12, p = 0,04). p-ERK expression correlated significantly with DFS in univariate analysis in the whole patient cohort (HR 1.03, 95%CI 1.00-1.05, p = 0.04) and cisplatin/carboplatin group (HR 1.03, 95%CI 1.00-1.07, p = 0.04). PTEN-expression did not correlate with OS/DFS/LRC. Better organoid response to everolimus correlated significantly to higher p-mTOR expression (Rs = - 0.731, p = 0.04). CONCLUSIONS: High p-mTOR expression predicts and high p-ERK expression tends to predict worse treatment outcome in HPV negative HNSCC patients treated with chemoradiation, providing additional evidence that these markers are candidate prognostic biomarkers for survival in this patient population. Also this study shows that the use of HNSCC organoids for biomarker research has potential. The role of PTEN expression as prognostic biomarker remains unclear, as consistent evidence on its prognostic and predictive value is lacking.

Efficacy and toxicity of vemurafenib and cobimetinib in relation to plasma concentrations, after administration via feeding tube in patients with BRAF-mutated thyroid cancer: a case series and review of literature.

INTRODUCTION: The combination of vemurafenib, a proto-oncogene B-Raf inhibitor (BRAFi) and cobimetinib, an inhibitor of mitogen-activated protein kinase kinase (MEKi) has shown to improve survival in patients with BRAF V600-mutated melanoma. BRAF mutations are also frequently detected driver mutations in other tumor types, including thyroid carcinoma. Since thyroid carcinoma is not a labeled indication for BRAF/MEKi, a cohort for patients with BRAF V600-mutated thyroid carcinoma was opened within the Drug Rediscovery Protocol (DRUP), a national ongoing pan-cancer multi-drug trial, in which patients receive off-label treatment with approved drugs based on their molecular tumor profile. RESULTS: Here, we present two patients with BRAF-mutated thyroid carcinoma, who were successfully treated with vemurafenib/cobimetinib administered via a feeding tube. Plasma concentrations of vemurafenib and cobimetinib were determined. A partial response was observed in both patients, but they experienced significant toxicity. CONCLUSION: Our cases show that vemurafenib/cobimetinib treatment is effective in BRAF V600-mutated thyroid carcinoma, also when administered via a feeding tube. Although serious side effects occurred in both patients, we hypothesize that this was not attributable to the administration route. Therefore, administration of vemurafenib/cobimetinib by feeding tube is feasible and effective. TRIAL REGISTRATION: Clinical trial identification: NCT02925234.

Validation of skeletal muscle mass assessment at the level of the third cervical vertebra in patients with head and neck cancer.

BACKGROUND: Low skeletal muscle mass (SMM) is associated with adverse outcomes. SMM is often assessed at the third lumbar vertebra (L3) on abdominal imaging. Abdominal imaging is not routinely performed in patients with head and neck cancer (HNC). We aim to validate SMM measurement at the level of the third cervical vertebra (C3) on head and neck imaging. MATERIAL AND METHODS: Patients with pre-treatment whole-body computed tomography (CT) between 2010 and 2018 were included. Cross-sectional muscle area (CSMA) was manually delineated at the level of C3 and L3. Correlation coefficients and intraclass correlation coefficients (ICCs) were calculated. Cohen's kappa was used to assess the reliability of identifying a patient with low SMM. RESULTS: Two hundred patients were included. Correlation between CSMA at the level of C3 and L3 was good (r = 0.75, p < 0.01). Using a multivariate formula to estimate CSMA at L3, including gender, age, and weight, correlation improved (r = 0.82, p < 0.01). The agreement between estimated and actual CSMA at L3 was good (ICC 0.78, p < 0.01). There was moderate agreement in the identification of patients with low SMM based on the estimated lumbar skeletal muscle mass index (LSMI) and actual LSMI (Cohen's κ: 0.57, 95%CI 0.45-0.69). CONCLUSIONS: CSMA at C3 correlates well with CSMA at L3. There is moderate agreement in the identification of patients with low SMM based on the estimated lumbar SMI (based on measurement at C3) and actual LSMI.

Predictive Value of EGFR-PI3K-AKT-mTOR-Pathway Inhibitor Biomarkers for Head and Neck Squamous Cell Carcinoma: A Systematic Review.

BACKGROUND: Understanding molecular pathogenesis of head and neck squamous cell carcinomas (HNSCC) has considerably improved in the last decades. As a result, novel therapeutic strategies have evolved, amongst which are epidermal growth factor receptor (EGFR)-targeted therapies. With the exception of cetuximab, targeted therapies for HNSCC have not yet been introduced into clinical practice. One important aspect of new treatment regimes in clinical practice is presence of robust biomarkers predictive for therapy response. METHODS: We performed a systematic search in PubMed, Embase and the Cochrane library. Articles were included if they investigated a biomarker for targeted therapy in the EGFR-PI3K-AKT-mTOR-pathway. RESULTS: Of 83 included articles, 52 were preclinical and 33 were clinical studies (two studies contained both a preclinical and a clinical part). We classified EGFR pathway inhibitor types and investigated the type of biomarker (biomarker on epigenetic, DNA, mRNA or protein level). CONCLUSION: Several EGFR-PI3K-AKT-mTOR-pathway inhibitor biomarkers have been researched for HNSCC but few of the investigated biomarkers have been adequately confirmed in clinical trials. A more systematic approach is needed to discover proper biomarkers as stratifying patients is essential to prevent unnecessary costs and side effects.

The predictive and prognostic value of low skeletal muscle mass for dose-limiting toxicity and survival in head and neck cancer patients receiving concomitant cetuximab and radiotherapy.

PURPOSE: This study aims to investigate the predictive value of low skeletal muscle mass (SMM) for cetuximab dose-limiting toxicity (DLT) and its prognostic value in head and neck squamous cell carcinoma (HNSCC) patients treated with concomitant cetuximab and radiotherapy. METHODS: Patients diagnosed with HNSCC and treated with primary or adjuvant concomitant cetuximab and radiotherapy were included. Clinical and demographic variables were retrospectively retrieved and SMM was measured at the level of the third cervical vertebra using pre-treatment diagnostic computed tomography or magnetic resonance imaging. An optimal cut-off value for low SMM was determined based on the lowest log-likelihood associated with cetuximab DLT. A multivariate linear regression model was used to determine predictive factors for cetuximab DLT. The prognostic value of low SMM for disease-free and overall survival was analyzed using Kaplan-Meier curves. RESULTS: The optimal cut-off value for low SMM as a predictor of cetuximab DLT was an LSMI ≤ 45.2 cm2/m2. Of the 91 included patients, 74.7% had low SMM and 30.8% experienced cetuximab DLT. At multivariate analysis, low SMM had no predictive value for DLT (OR 0.83; 95% CI 0.27-2.56; p = 0.74). The Kaplan-Meier curve demonstrated that patients with low SMM had significantly lower overall survival (Log Rank χ2 = 5.87; p = 0.02). CONCLUSION: Low SMM is highly prevalent in HNSCC patients treated with concomitant cetuximab and radiotherapy. Low SMM has no predictive value for cetuximab DLT in HNSCC patients. Low SMM is probably not a prognostic factor for overall survival in highly selected HNSCC patients treated with concomitant cetuximab and radiotherapy and unfit for platin-based chemotherapy.

The Drug Rediscovery protocol facilitates the expanded use of existing anticancer drugs.

The large-scale genetic profiling of tumours can identify potentially actionable molecular variants for which approved anticancer drugs are available1-3. However, when patients with such variants are treated with drugs outside of their approved label, successes and failures of targeted therapy are not systematically collected or shared. We therefore initiated the Drug Rediscovery protocol, an adaptive, precision-oncology trial that aims to identify signals of activity in cohorts of patients, with defined tumour types and molecular variants, who are being treated with anticancer drugs outside of their approved label. To be eligible for the trial, patients have to have exhausted or declined standard therapies, and have malignancies with potentially actionable variants for which no approved anticancer drugs are available. Here we show an overall rate of clinical benefit-defined as complete or partial response, or as stable disease beyond 16 weeks-of 34% in 215 treated patients, comprising 136 patients who received targeted therapies and 79 patients who received immunotherapy. The overall median duration of clinical benefit was 9 months (95% confidence interval of 8-11 months), including 26 patients who were experiencing ongoing clinical benefit at data cut-off. The potential of the Drug Rediscovery protocol is illustrated by the identification of a successful cohort of patients with microsatellite instable tumours who received nivolumab (clinical benefit rate of 63%), and a cohort of patients with colorectal cancer with relatively low mutational load who experienced only limited clinical benefit from immunotherapy. The Drug Rediscovery protocol facilitates the defined use of approved drugs beyond their labels in rare subgroups of cancer, identifies early signals of activity in these subgroups, accelerates the clinical translation of new insights into the use of anticancer drugs outside of their approved label, and creates a publicly available repository of knowledge for future decision-making.

Phase I and pharmacological study of pazopanib in combination with oral topotecan in patients with advanced solid tumours.

BACKGROUND: This phase I study evaluated the safety, tolerability, maximum tolerated dose (MTD) and pharmacokinetics of two dosing schedules of oral topotecan in combination with pazopanib in patients with advanced solid tumours. METHODS: Stage I of this study was to determine whether there was an impact of pazopanib on topotecan exposure. In stage II, the MTD and safety profile of oral topotecan given weekly on days 1, 8 and 15 in a 28-day cycle; or daily-times-five on days 1-5 in a 21-day cycle, both in combination with daily pazopanib, were explored. RESULTS: In total, 67 patients were enroled. Pazopanib co-administration caused a substantial increase in exposure to total topotecan (1.7-fold) compared with topotecan alone, which is considered clinically relevant. Topotecan had no effect on pazopanib concentrations. Safety findings were consistent with the known profile of both agents. There were three drug-related deaths, liver failure, tumour haemorrhage and myelosuppression. Two patients experienced dose-limiting toxicities (DLTs; hand-foot syndrome, myelosuppression and diarrhoea) on the weekly topotecan schedule and four patients experienced DLTs (myelosuppression) on the daily-times-five topotecan schedule. When combined with pazopanib, 800 mg daily, the recommended doses for oral topotecan are: 8 mg weekly and 2.5 mg daily-times-five. Seven of eight patients with partial response had platinum-resistant ovarian cancer. In addition, 54% of patients had stable disease with 22% stable for 6 months. CONCLUSIONS: Total topotecan exposure is 1.7-fold higher when co-administered with pazopanib. Both schedules of administration were tolerated and would permit further evaluation, especially the weekly schedule.

Eribulin mesylate pharmacokinetics in patients with solid tumors receiving repeated oral ketoconazole.

Purpose To study the influence of repeated oral administration of ketoconazole, a potent CYP3A4 inhibitor, on the plasma pharmacokinetics of eribulin mesylate administered by single-dose intravenous infusion. Eribulin mesylate is a non-taxane microtubule dynamics inhibitor that is currently under development in phase I-III trials for the treatment of solid tumors. Experimental design A randomized, open-label, two treatments, two sequences, crossover phase I study was performed in patients with advanced solid tumors. Treatments were given on day 1 and day 15 and consisted of 1.4 mg/m(2) eribulin mesylate alone or 0.7 mg/m(2) eribulin mesylate plus 200 mg ketoconazole on the day of eribulin mesylate administration and the following day. Pharmacokinetic sampling for determination of eribulin plasma concentration was performed up to 144 h following administration of eribulin mesylate. Also safety and anti-tumor activity were determined. Results Pharmacokinetic sampling and analysis was completed in ten patients. Statistical analysis of dose-normalized log-transformed AUC0-∞ and Cmax indicated that single-dose exposure of eribulin was not statistically different when co-administered with ketoconazole (ratio of geometric least square means: 0.95 (90%CI: 0.80-1.12) and 0.97 (90%CI: 0.83-1.12), respectively) in patients with solid tumors. Ketoconazole had no effect on eribulin clearance and elimination half-life. The most frequently reported treatment related adverse events were fatigue and nausea, each reported in 8/12 patients. Seven patients (58.3 %) achieved stable disease as best overall response. Conclusions The results indicate that eribulin mesylate can be safely co-administered with ketoconazole. Drug-drug interactions are not expected with other CYP3A4 inhibitors.

Pharmacokinetics of eribulin mesylate in patients with solid tumors and hepatic impairment.

PURPOSE: The aim of this study was to determine the plasma pharmacokinetics of eribulin mesylate in patients with solid tumors with mild and moderate hepatic impairment. PATIENTS AND METHODS: A phase I, pharmacokinetic study was performed in patients with advanced solid tumors and normal hepatic function or Child-Pugh A (mild) or Child-Pugh B (moderate) hepatic impairment. Treatments were given on day 1 and 8 of a 21-day cycle and consisted of 1.4, 1.1 and 0.7 mg/m(2) eribulin mesylate, for normal hepatic function, Child-Pugh A and B hepatic impairment, respectively. Also safety and anti-tumor activity were determined. RESULTS: Hepatic impairment increased exposure to eribulin. In patients with Child-Pugh A (N = 7) and Child-Pugh B (N = 5), mean dose-normalized AUC(0-∞) was 1.75-fold (90 % confidence intervals (CI): 1.16-2.65) and 2.48-fold (90 % CI: 1.57-3.92) increased, respectively, compared with patients who have normal function (N = 6). The most frequently reported treatment-related events were alopecia (12/18) and fatigue (7/18) and these were observed across all groups. Nine patients (50 %) had stable disease as best response. CONCLUSIONS: A reduced dose of 1.1 and 0.7 mg/m(2) of eribulin mesylate is recommended for patients with Child-Pugh A or B hepatic impairment, respectively.

Circulating tumor cell detection in advanced non-small cell lung cancer patients by multi-marker QPCR analysis.

BACKGROUND: The aim of this study was to explore circulating tumor cell (CTC) detection in advanced non-small cell lung cancer (NSCLC). CTCs may not only serve as a prognostic marker in selected tumor types, but may also be useful as pharmacodynamic marker in drug development. METHODS: Fourty-six advanced NSCLC patients and fourty-six healthy controls were included in the study and 8.0 ml of peripheral blood was obtained from each of the participants. Immunomagnetic bead enrichment for cells expressing epithelial cell adhesion molecule (EpCAM) was performed, followed by multi-marker quantitative real-time PCR of a panel of marker genes: cytokeratin 7 (CK7), cytokeratin 19 (CK19), human epithelial glycoprotein (EGP) and fibronectin 1 (FN1). Using quadratic discriminant analysis (QDA), expression values were combined into a single score, which indicated CTC-positivity or -negativity. Test characteristics were assessed using receiver operating characteristic (ROC) curve analysis. RESULTS: ROC curve analysis showed capability of discrimination between advanced NSCLC patients and healthy controls (area=0.712; 95% CI 0.606-0.819; P<0.001). A cut-off minimizing overall misclassification for QDA-positivity reached a sensitivity of 46% (95% CI 31-61) and a specificity of 93% (95% CI 82-99). CONCLUSIONS: In this exploratory study, an assay was developed for discriminating CTCs in peripheral blood samples of advanced NSCLC patients from healthy controls. The assay demonstrated an acceptable sensitivity in combination with good specificity. Further validation studies should take place in NSCLC patients and a matched control group.

A multimarker QPCR-based platform for the detection of circulating tumour cells in patients with early-stage breast cancer.

BACKGROUND: The detection of circulating tumour cells (CTCs) has been linked with poor prognosis in advanced breast cancer. Relatively few studies have been undertaken to study the clinical relevance of CTCs in early-stage breast cancer. METHODS: In a prospective study, we evaluated CTCs in the peripheral blood of 82 early-stage breast cancer patients. Control groups consisted of 16 advanced breast cancer patients and 45 healthy volunteers. The CTC detection was performed using ErbB2/EpCAM immunomagnetic tumour cell enrichment followed by multimarker quantitative PCR (QPCR). The CTC status and common clinicopathological factors were correlated to relapse-free, breast cancer-related and overall survival. RESULTS: Circulating tumour cells were detected in 16 of 82 (20%) patients with early-stage breast cancer and in 13 out of 16 (81%) with advanced breast cancer. The specificity was 100%. The median follow-up time was 51 months (range: 17-60). The CTC positivity in early-stage breast cancer patients resulted in significantly poorer relapse-free survival (log rank test: P=0.003) and was an independent predictor of relapse-free survival (multivariate hazard ratio=5.13, P=0.006, 95% CI: 1.62-16.31). CONCLUSION: The detection of CTCs in peripheral blood of early-stage breast cancer patients provided prognostic information for relapse-free survival.

Cloacal Lactobacillus isolates from broilers show high prevalence of resistance towards macrolide and lincosamide antibiotics.

Eighty-seven Lactobacillus strains isolated from cloacal swabs of broiler chickens derived from 20 different farms in Belgium were identified to species level and tested for susceptibility to macrolide and lincosamide antibiotics. Five different Lactobacillus species were identified as being predominantly present in the cloacae of broilers: Lactobacillus crispatus, Lactobacillus salivarius subsp. salivarius, Lactobacillus amylovorus, Lactobacillus gallinarum and Lactobacillu sreuteri. Acquired resistance prevalence to macrolides and lincosamides was very high in the investigated lactobacilli: 89% of the strains were resistant to either or both lincosamide and macrolide class antibiotics. The vast majority of these resistant strains (96%) displayed constitutive resistance. More than one-half of the macrolide and/or lincosamide resistant strains carried an erm(B), erm(C), mef(A), lnu(A) gene or a combination of these genes.

Cloacal Lactobacillus isolates from broilers often display resistance toward tetracycline antibiotics.

Lactobacillus crispatus, L. reuteri, L. amylovorus, L. gallinarum, and L. salivarius subsp. salivarius strains isolated from cloacal swabs of broiler chickens derived from 20 different farms in Belgium were tested for susceptibility to tetracycline and minocycline. Acquired resistance percentages to these antibiotics were extremely high for L. crispatus, L. reuteri, L. gallinarum, and L. salivarius subsp. salivarius (75%-100%). L. amylovorus on the contrary, displayed lower resistance percentages (25%) toward minocycline and tetracycline. In several strains, resistance against the tetracycline antibiotics was associated with the presence of the resistance genes tet(K), tet(L), tet(M), tet(W), and tet(Z). To our knowledge, this is the first report of tet(Z) in lactobacilli and tet(K), tet(L), and tet(W) in lactobacilli identified to species level. Our findings strengthen the evidence of intestinal Lactobacillus species acting as a pool of antimicrobial resistance genes urging the need for prudent use of tetracycline antibiotics in poultry production.

Comparison and transferability of the erm (B) genes between human and farm animal streptococci.

To obtain better insights into the possible exchange of resistance genes between human and animal streptococci, the sequences of the erm (B) genes of streptococcal isolates from humans, pigs, pork carcasses, chickens, and calves were compared. Identical erm (B) gene sequences were present in strains from humans, pigs, pork carcasses, and calves. During in vitro mating experiments, the erm (B) gene was exchanged between porcine Streptococcus suis and human S. pneumoniae, S. pyogenes, and S. oralis strains. The presence of different tetracycline resistance genes and the int Tn 1545 gene was determined in animal streptococci carrying the erm (B) gene. Although tet(M) and int Tn 1545 genes were detected in 24% of the porcine and pork carcass streptococcal strains, the tet(O) gene was the predominant tetracycline resistance gene in these strains (81%). The latter gene was co-transferred with the erm (B) gene from porcine S. suis strains to human streptococci in the mating experiments. These results show that, identical erm (B) gene sequences were present in animal and human streptococci and that transfer of the erm (B) gene from porcine S. suis to human streptococci and vice versa is possible, but probably occurs at a low frequency.

Identification of enterococcal, streptococcal and Weissella species in the faecal flora of individually owned dogs.

AIMS: To improve the limited information on the composition of the faecal Gram-positive coccal flora of healthy dogs by the use of a molecular identification method. METHODS AND RESULTS: Faecal swabs were collected for the selective isolation of Gram-positive coccal strains. Colonies with enterococcal- and streptococcal-like morphology were identified by tRNA intergenic length polymorphism analysis (tDNA-PCR). Fourteen known species belonging to three genera (Enterococcus, Streptococcus and Weissella) and one alleged new enterococcal species were found. CONCLUSIONS: The faecal flora of dogs comprises an unusually broad diversity of culturable Gram-positive coccal species with Enterococcus faecalis being most frequently present followed by not less than six other species of about equal importance. SIGNIFICANCE AND IMPACT OF THE STUDY: Many human- and animal-associated enterococci and streptococci are also present in dog faeces together with the largely uncharacterized Weissella cibaria and a group of strains resembling Enterococcus dispar, but representing a distinct and hitherto unknown species. Phenotypic characteristics of the latter two species were determined and the test results were compared with the species descriptions of W. cibaria and E. dispar respectively.

Effect of avilamycin fed to chickens on E. faecium counts and on the selection of avilamycin-resistant E. faecium populations.

This study was conducted to investigate the effect of avilamycin used as a growth promoter on the number of E. faecium and on avilamycin-resistant E. faecium in the intestines of broilers over time. Avilamycin was added at 13.6 ppm to the feed of chickens during 28 days or during a typical growth period of 42 days; a nonmedicated group was included. Three hundred twenty-four Ross broiler chickens were equally distributed over the different groups in a treatment trial and kept in three isolation rooms. In each room, two replicates of the three experimental groups were kept in separate pens. At various time points, samples from different intestinal compartments or the feces were serially diluted and plated on avilamycin-supplemented and on unsupplemented Slanetz and Bartley (SL) media, and E. faecium counts were recorded. Only in the feces and only on the last sampling day was a significant decrease noted in the E. faecium counts in chickens treated with avilamycin for 42 days. Intermediate resistant (MIC 4-8 microg/ml) and resistant strains (MIC>or=16 microg/ml) were isolated from all groups, and there was a rise in prevalence over time. Pulsed-field gel electrophoresis profiles of these strains indicated clonal spread from one pen to another within the same room. The ratio between the counts of E. faecium isolated on antibiotic-supplemented to unsupplemented plates was significantly higher at the end of the trial in the feces samples from the group fed avilamycin for 42 days compared to the other groups, indicating a selective effect of avilamycin.

Enterococcus saccharominimus sp. nov., from dairy products.

Four isolates, which were obtained from Belgian, Moroccan and Romanian dairy products, constituted a homogeneous but unidentified taxon after screening with whole-cell protein fingerprinting. Complete 16S rRNA gene sequence analysis classified representative strains in the genus Enterococcus. Highest sequence similarities of 98.6 and 98.0 % were obtained with the species Enterococcus sulfureus and Enterococcus saccharolyticus, respectively. Growth characteristics, biochemical features, tRNA intergenic length polymorphism analysis, DNA-DNA hybridization and DNA G+C contents of selected strains demonstrated that they represent a single, novel Enterococcus species. It differs phenotypically from other enterococci in characteristics commonly considered as typical of this genus: no growth in 6.5 % NaCl or 0.4 % sodium azide, and no acid production from a wide range of carbohydrates. The name Enterococcus saccharominimus sp. nov. is proposed for this novel species; the type strain (LMG 21727(T)=CCM 7220(T)) was isolated from contaminated pasteurized cow's milk.

In vitro growth inhibition of major mastitis pathogens by Staphylococcus chromogenes originating from teat apices of dairy heifers.

Earlier field observations suggest that teat apex colonization by Staphylococcus chromogenes pre-partum in dairy heifers protects udder quarters against elevated somatic cell counts early post-partum. To explain these findings, the in vitro inhibitory capability of S. chromogenes from teat apices of heifers towards some major mastitis pathogens was tested using a modified cross-streaking method. Two out of 10 S. chromogenes isolates, both originating from two different teats from the same heifer, consistently inhibited growth of all Staphylococcus aureus, Streptococcus dysgalactiae, and Streptococcus uberis strains, but none of the Escherichia coli strains. The present study, therefore, supports the protective effect of teat apex colonization by S. chromogenes by in vitro production of inhibitory substances.

Antibiotic resistance among fecal indicator bacteria from healthy individually owned and kennel dogs.

Escherichia coli and Enterococcus faecalis strains isolated from anal swabs of clinically healthy dogs were examined for the presence of acquired antimicrobial resistance. The strains originated from dogs of 92 different owners and from eight breeding kennels. The purpose of the present study was to evaluate the resistance situation in the intestinal flora of the dog to assess the possible role of the dog flora as a reservoir of antimicrobial resistance. Multiple resistance was rarely found in E. coli strains collected from individually owned dogs, in contrast with strains from kennel dogs. Resistance to ampicillin, trimethoprim, and sulfamethoxazole was significantly less prevalent in E. coli from privately owned dogs than in strains from kennel dogs. Resistance rates against tetracycline and macrolides were unexpectedly high in E. faecalis strains. Two and three E. faecalis strains from individually owned dogs and kennel dogs, respectively, were resistant to gentamicin, an antibiotic often used for treating enterococcal infections in humans. This study demonstrates that resistance percentages may fluctuate with the choice of dog population. The observed antimicrobial resistance percentages indicate that the flora of healthy dogs may act as a reservoir of resistance genes.

Streptococcus minor sp. nov., from faecal samples and tonsils of domestic animals.

Nine isolates, which were obtained from tonsils, anal swabs and faeces of dogs and from tonsils of a cat and a calf, constituted a homogeneous but unidentified taxon after screening with tRNA intergenic length polymorphism analysis and whole-cell protein fingerprinting. 16S rDNA sequence analysis classified representative strains in the genus Streptococcus. Highest sequence similarity (95.9 %) was obtained with Streptococcus ovis. Growth characteristics, biochemical features, DNA-DNA hybridization and DNA G+C contents of selected strains demonstrated that they represent a single, novel streptococcal species. The name Streptococcus minor sp. nov. is proposed for the novel species; the type strain (ON59(T)=LMG 21734(T)=CCUG 47487(T)) was isolated from a dog tonsil.