Margaret S. Jackson

The ecology of Staphylococcus species in the oral cavity.

Whilst the diversity of organisms present in the oral cavity is well accepted, there remains considerable controversy as to whether Staphylococcus spp. play a role in the ecology of the normal oral flora. Surprisingly little detailed work has been performed on the quantitative and qualitative aspects of colonisation or infection either by coagulase-negative staphylococci (CNS) or S. aureus. The latter is especially interesting in the light of present difficulties in eradicating carriage of methicillin-resistant S. aureus (MRSA) from the oropharynx in affected individuals. This paper reviews the current knowledge of staphylococcal colonisation and infection of the oral cavity in health and disease. S. aureus has been isolated from a wide range of infective oral conditions, such as angular cheilitis and parotitis. More recently, a clinical condition classified as staphylococcal mucositis has emerged as a clinical problem in many debilitated elderly patients and those with oral Crohns disease. Higher carriage rates of both CNS or S. aureus, or both, in patients prone to joint infections raises the interesting possibility of the oral cavity serving as a potential source for bacteraemic spread to compromised joint spaces. In conclusion, there is a surprising paucity of knowledge regarding the role of oral staphylococci in both health and disease. Further work in this area may lead to benefits, such as improved decolonisation regimens for eradication of MRSA and acknowledgement of the mouth as a source of bacteraemic staphylococci.

Staphylococcus aureus in the oral cavity: a three-year retrospective analysis of clinical laboratory data

Objective A retrospective analysis of laboratory data to investigate the isolation of Staphylococcus aureus from the oral cavity and facial area in specimens submitted to a regional diagnostic oral microbiology laboratory.Methods A hand search of laboratory records for a three-year period (1998–2000) was performed for specimens submitted to the regional diagnostic oral microbiology laboratory based at Glasgow Dental Hospital and School. Data were collected from forms where S. aureus was isolated. These data included demographics, referral source, specimen type, methicillin susceptibility and clinical details.Results For the period 1998–2000, there were 5,005 specimens submitted to the laboratory. S. aureus was isolated from 1,017 specimens, of which 967 (95%) were sensitive to methicillin (MSSA) and 50 (5%) were resistant to methicillin (MRSA). The 1,017 specimens were provided from 615 patients. MRSA was isolated from 37 (6%) of patients. There was an increasing incidence of S. aureus with age, particularly in the >70 years age group. The most common specimen from which MSSA was isolated was an oral rinse (38%) whilst for MRSA isolates this was a tongue swab (28%). The clinical condition most commonly reported for MSSA isolates was angular cheilitis (22%). Erythema, swelling, pain or burning of the oral mucosa was the clinical condition most commonly reported for MRSA isolates (16%). Patients from whom the MSSA isolates were recovered were most commonly (55%) seen in the oral medicine clinic at the dental hospital, whilst patients with MRSA were more commonly seen in primary care settings such as nursing homes, hospices and general dental practice (51%).Conclusion In line with more recent surveys, this retrospective study suggests that S. aureus may be a more frequent isolate from the oral cavity than hitherto suspected. A small proportion of the S. aureus isolates were MRSA. There were insufficient data available to determine whether the S. aureus isolates were colonising or infecting the oral cavity. However, the role of S. aureus in several diseases of the oral mucosa merits further investigation.

High prevalence of non-albicans yeasts and detection of anti-fungal resistance in the oral flora of patients with advanced cancer

Oral fungal infections frequently develop in individuals with advanced cancer. This study examined the oral mycological flora of 207 patients receiving palliative care for advanced malignant disease. Demographic details and a clinical history were documented from each participant. A tongue swab was collected and cultured on CHROMAgar Candida® (CHROMAgar Paris, France). All yeasts were identified by germ tube test, API ID 32C profiles and, for Candida dubliniensis, by species-specific PCR. Susceptibility to fluconazole and itraconazole was determined by a broth microdilution assay according to the National Committee for Clinical Laboratory Standards (NCCLS). At time of sampling, 54 (26%) of the 207 subjects had clinical evidence of a fungal infection and yeasts were isolated from 139 (67%) individuals. In total, 194 yeasts were isolated, of which 95 (49%) were Candida albicans. There was a high prevalence of Candidia glabrata (47 isolates) of which 34 (72%) were resistant to both fluconazole and itraconazole. All nine isolates of C. dubliniensis recovered were susceptible to both azoles. No relationship was established between anti-fungal usage in the preceding three months and the presence of azole resistant yeasts. This study of patients with advanced cancer has demonstrated a high incidence of oral colonization with non-C. albicans yeasts, many of which had reduced susceptibility to fluconazole and itraconazole. The role of improved oral care regimes and novel anti-fungal drugs merits further attention, to reduce the occurrence of fungal infection in these patients.

Bordetella petrii Clinical Isolate

We describe the first clinical isolate of Bordetella petrii from a patient with mandibular osteomyelitis. The only previously documented isolation of B. petrii occurred after the initial culture of a single strain from an environmental source.

Antimicrobial susceptibility of viridans group streptococcal blood isolates to eight antimicrobial agents

A total of 155 viridans group streptococci blood culture isolates identified by the Rapid ID32 Strep system were tested for their minimum inhibitory concentrations (MICs) to penicillin, amoxicillin, ceftriaxone, erythromycin, clindamycin, rifampicin, vancomycin and teicoplanin using the E-test. The following species were identified: S. oralis (n=67), S. mitis (n=66), S. sanguis (n=7), S. salivarius (n=5), S. parasanguis (n=4), S. gordonii (n=3) and S. mutans (n=3). S. oralis and S. mitis demonstrated the highest levels of resistance to the agents tested. There were 27% of S. oralis isolates resistant to pencillin, 51% resistant to erythromycin and 6% resistant to clindamycin. For S. mitis 11% were resistant to penicillin, 40% resistant to erythromycin and 3% resistant to clindamycin. Penicillin resistant isolates (MIC≥2 mg/l) also demonstrated decreased susceptibility to other antimicrobial agents tested in this study. High level resistance (MIC≥2 mg/l) to ceftriaxone was found in 12 isolates. The isolates identified as ceftriaxone resistant comprised S. oralis (n=7), S. mitis (n=4) and S. parasanguis (n=1). This study has highlighted the difference in susceptibility between different species of viridans group streptococci. These findings are of concern in the light of spread of antibiotic resistance genes from S. oralis and S. mitis to the more invasive pneumococcus.

oral medicine: Barriers to the use of a diagnostic oral microbiology laboratory by general dental practitioners

Objective To identify barriers on the use of diagnostic microbiology facilities in general dental practice.Design A cross-sectional survey using a postal questionnaire.Setting Primary/secondary care interface between the diagnostic oral microbiology laboratory, University of Glasgow Dental Hospital and School, Glasgow and dental practitioners within the surrounding health boards, 1998.Subjects All GDPs (797) within Argyll and Clyde, Ayrshire and Arran, Lanarkshire and Greater Glasgow Health Boards.Main outcome measures The responses were expressed as both absolute and relative frequencies.Results Responses were received from 430 (55%). The most frequent reason for failure to use the service was lack of information, with more than half of the respondents claiming to be unaware of the facility. Lack of request forms and sampling equipment were also viewed as barriers to using the service.Conclusions The laboratory is failing to successfully communicate its role in addressing the growing burden of antibiotic resistance in the community and must be more proactive in encouraging appropriate use and increasing accessibility of the service to GDPs.