Methicillin susceptibility testing of staphylococci by Etest and comparison with agar dilution and mecA detection.

The susceptibility to methicillin of 44 Staphylococcus aureus and 120 coagulase-negative staphylococci (CNS) was determined by Etest, agar dilution and presence of the mecA gene. There was agreement between the results of all methods when testing S. aureus. However, discrepancies occurred with CNS when cultural methods were compared with presence of the mecA gene. mecA-positive isolates tested as resistant more often with agar dilution on Columbia agar plus 5% NaCl than by Etest.

Considerations in predicting mental health care use: implications for managed care plans.

Managed care plans and other health care providers face a difficult task in predicting outpatient mental health services use. Existing research offers some guidance, but our knowledge of which factors influence use is confounded by methodological problems and sampling constraints. Consequently, available findings are insufficient for developing accurate predictions, which managed care plans need in order to formulate fiscally responsible service delivery contracts. This article reviews the primary data sources and research on ambulatory mental health services. On the basis of this review, the probability and intensity of outpatient visits are estimated. The primary predictors of use are also examined because they may help managed care plans forecast use by a given population or group of enrollees. Gender, age, race, education, health status, and insurance coverage are several variables surfacing as statistically significant predictors of use. The implications for planning capitated mental health services are discussed.

Effects of culture media on detection of methicillin resistance in Staphylococcus aureus and coagulase negative staphylococci by disc diffusion methods.

AIMS: To test 10 culture media for their ability to detect resistance and sensitivity of staphylococci to methicillin by disc diffusion. METHODS: Fifty strains of Staphylococcus aureus and 135 strains of coagulase negative staphylococci were tested using Columbia, Diagnostic Sensitivity Test, Mueller Hinton, Sensitest and Iso-sensitest agars with and without 5% added sodium chloride. Cultures were examined after 18 and 40 hours of incubation. The diameter of the zone and its characteristics were recorded and these media were assessed for their ability to produce clear, readable zones of inhibition. Changes in the variables which determined resistance were investigated. Results were analysed allowing a zone diameter reduction of 8 mm and 10 mm compared with the control in addition to the standard 6 mm. RESULTS: Columbia agar with added sodium chloride supported the growth of all strains, detected the highest number of resistant strains, and was the easiest to read. Resistance was detected after 18 hours in most resistant strains, but some required 40 hours of incubation. There was poor agreement, however, on this medium (63-94%) between disc diffusion and the reference MIC method for sensitive strains. Allowing a greater reduction in zone size resulted in more agreement with sensitive strains but with consequently lowered detection of resistant strains. The other media showed some growth failures and more zones that were difficult to read. More resistance was detected when incubation was prolonged to 40 hours but this was consistently less than on Columbia agar with added salt. CONCLUSIONS: None of the media detected all of the resistant strains. Columbia agar with added salt was the most satisfactory medium in this respect, but it misidentified up to 37% of the sensitive strains as resistant. Methicillin susceptibility testing by disc diffusion testing is unreliable.

Actinomyces odontolyticus isolated from the female genital tract.

Actinomyces odontolyticus was isolated from genital tract specimens from 4.8% of 561 women fitted with intrauterine contraceptive devices and from 4% of 101 women with pelvic inflammatory disease and 1.8% of 525 women without pelvic inflammatory disease who were not known to be intrauterine contraceptive device wearers. The strains were isolated by prolonged anaerobic incubation of blood agar, with or without added 5% metronidazole or 1% neomycin. A odontolyticus has not been previously reported in cervico-vaginal specimens, and possible reasons for this are discussed.

Diagnosis of anaerobic infection by gas chromatographic estimation of volatile fatty acids.

Nine hundred and eighty-one fluid specimens were analysed by culture and by gas chromatography. The presence of obligate anaerobes was best predicted if one or more of the volatile acids isobutyric, butyric, isovaleric, valeric, isocaproic or caproic acid were detected in the specimen. Propionic acid was not a good indicator of the presence of obligate anaerobes. The agreement between gas chromatography and culture for obligate anaerobes in the main study (841 specimens, 232 culture positive) was: co-positivity 82%; co-negativity 92%. Falsely negative specimens contained anaerobes which had probably not produced sufficient of their characteristic volatile fatty acids to be detected. When it was the sole infecting anaerobe, Bacteroides fragilis seemed especially likely to be missed by gas chromatography. Forty-five of the 51 falsely positive specimens probably represented failure to culture anaerobes rather than spurious volatile fatty acid detection.