Antimicrobial susceptibility profile of clinically relevant Bacteroides, Phocaeicola, Parabacteroides and Prevotella species, isolated by eight laboratories in the Netherlands

OBJECTIVES

Recently, reports on antimicrobial-resistant Bacteroides and Prevotella isolates have increased in the Netherlands. This urged the need for a surveillance study on the antimicrobial susceptibility profile of Bacteroides, Phocaeicola, Parabacteroides and Prevotella isolates consecutively isolated from human clinical specimens at eight different Dutch laboratories.

METHODS

Each laboratory collected 20-25 Bacteroides (including Phocaeicola and Parabacteroides) and 10-15 Prevotella isolates for 3 months. At the national reference laboratory, the MICs of amoxicillin, amoxicillin/clavulanic acid, piperacillin/tazobactam, meropenem, imipenem, metronidazole, clindamycin, tetracycline and moxifloxacin were determined using agar dilution. Isolates with a high MIC of metronidazole or a carbapenem, or harbouring cfiA, were subjected to WGS.

RESULTS

Bacteroides thetaiotaomicron/faecis isolates had the highest MIC90 values, whereas Bacteroides fragilis had the lowest MIC90 values for amoxicillin/clavulanic acid, piperacillin/tazobactam, meropenem, imipenem and moxifloxacin. The antimicrobial profiles of the different Prevotella species were similar, except for amoxicillin, for which the MIC50 ranged from 0.125 to 16 mg/L for Prevotella bivia and Prevotella buccae, respectively. Three isolates with high metronidazole MICs were sequenced, of which one Bacteroides thetaiotaomicron isolate harboured a plasmid-located nimE gene and a Prevotella melaninogenica isolate harboured a nimA gene chromosomally.Five Bacteroides isolates harboured a cfiA gene and three had an IS element upstream, resulting in high MICs of carbapenems. The other two isolates harboured no IS element upstream of the cfiA gene and had low MICs of carbapenems.

CONCLUSIONS

Variations in resistance between species were observed. To combat emerging resistance in anaerobes, monitoring resistance and conducting surveillance are essential.

[A renewed focus on extra-oral manifestations of oral infections]

Dental focal infections are extraoral manifestations caused by oral pathogens. Pathological oral conditions, such as periapical inflammation and periodontitis, can cause bacteremia. Dissemination of oral pathogens to nonoral sites can subsequently cause infections in extraoral tissues and organs. Cardiovascular infections and brain abscesses are the most common of these. The course of such infections can be lethal. In order to improve patient care, a closer collaboration between dental and medical caregivers is necessary.

Chromosome instability predicts the progression of premalignant oral lesions

OBJECTIVES

One of the main problems in reducing the incidence of oral squamous cell carcinoma (OSCC) is the inability to appropriately deal with leukoplakia. Accurately identifying lesions which will progress to malignancy is currently not possible. The present study aims to establish the value of chromosome instability (CI) detection by DNA image cytometry and FISH analysis for prognosis and monitoring of oral leukoplakia.

MATERIALS AND METHODS

For this purpose, we included from our archives 102 oral leukoplakia cases, which had been diagnosed between 1991 and 2008. Patient follow-up data were collected and the histopathological diagnosis was revised. CI assessment was carried out on paraffin-embedded tissue sections using both DNA image cytometry (ICM) and dual target FISH for chromosomes 1 and 7.

RESULTS

16 of 102 Patients developed carcinoma in situ or OSCC. Both detection methods were found to yield prognostic information independent of the histopathological diagnosis. CI was a strong individual marker of progression, with hazard ratios (HRs) of 7.2 and 6.8 for ICM and FISH respectively. Moreover, this approach seems suitable for monitoring lesions over time (especially ICM). Combining histopathology and CI enables subdivision of patients into three risk groups, with different probabilities of malignant progression.

CONCLUSION

CI detection seems a reliable method for risk assessment of oral premalignancies and its application may contribute to a better risk-counselling and appropriate treatment regimen or watchfull-waiting approach of patients.

No high-risk HPV detected in SCC of the oral tongue in the absolute absence of tobacco and alcohol--a case study of seven patients

INTRODUCTION

In recent years, there has been an increase in the number of patients with squamous cell carcinoma (SCC) of the mobile tongue in the absence of tobacco and alcohol. The literature suggests that human papilloma virus (HPV) may be involved in the development of SCC of the head and neck, especially in non-smoking and non-drinking patients. In the oral cavity, however, the presence of the HPV genome has been reported with various percentages. This may be due to misclassification of the oropharyngeal tongue as oral cavity subsite and the use of various detection methods.

MATERIALS AND METHODS

Therefore, we evaluated the role of HPV in seven consecutive non-smoking and non-drinking patients (2003-2006) with a SCC located at the oral, mobile tongue using in situ hybridization and SPF(10)Line Blot 25 polymerase chain reaction assays.

RESULTS

No HPV was detected in these specimens. To further determine whether a relationship exists between HPV and SCC in the absence of tobacco and alcohol, subsequent studies at specific locations are necessary.