Comparison of Mueller-Hinton Agar and Oxoid Sensitivity Test Medium in Antibiotic Susceptibility Testing of Escherichia coli

The in vitro activity of five antibiotics against 368 strains of Escherichia coli was determined by use of Mueller-Hinton agar and Oxoid sensitivity test medium. Minimal inhibiting concentrations were essentially identical with both media.     

Utility of an oral examination in a surgical clerkship.

To evaluate the utility of the oral examination in a surgical clerkship, we designed a prospective and randomized study to relate the subjective impressions of experienced examiners with an objective measure of cognitive knowledge. The examiners were asked to score the student's performance as honors, high satisfactory, satisfactory, or unsatisfactory, according to their subjective impression of the student's ability. Student performance was grouped according to oral examination performance. The cognitive performance in the honors group was significantly better than that of the other groups (Student's t-test, p = 0.05). There was a significant difference in cognitive performance for oral examination groups throughout the rotations (analysis of variance, p = 0.000; Kruskal Wallis, p = 0.05). The oral examination is useful to identify a high level of cognitive achievement but cannot discriminate between groups of median to low competence. It should be used for educational feedback, career counseling, residency recommendations, and professional development.     

Consistency of the tobacco withdrawal syndrome

The consistency of the tobacco withdrawal syndrome across repeated periods of abstinence was tested using a modified A-B-A-B design. The large majority of the signs and symptoms of tobacco withdrawal occurred during abstinence, returned to baseline, and then recurred during a second abstinence period. This finding suggests that the syndrome is reliable and can be studied with within-subject designs.     

Bactericidal Action of Bicarbonate Ion on Selected Periodontal Pathogenic Microorganisms

Organisms representative of soil, skin and fecal flora and of supragingival and subgingival flora were tested for inhibition of growth and killing by various salts (NaHCO₃, NaCl, MgSO₄). The antimicrobial activities of KHCO₃, NaF, sodium lauryl sulfate (SLS) and chloramine T were also compared with that of NaHCO₃, and the rate at which NaHCO₃ exerts its bactericidal effect was studied. Suspected periodontal pathogens were more susceptible to salts than were control non-oral bacteria. Supragingival plaque organisms showed intermediate susceptibility. Periodontal pathogens were more susceptible to NaHCO₃ than to NaCl; NaHCO₃ and KHCO₃ showed similar activity against all strains tested. Accordingly, the antibacterial activity of NaHCO₃ is not simply an osmotic effect and is due to the bicarbonate ion. NaF, SLS and chloramine T had greater antimicrobial activity than NaHCO₃. Supragingival bacteria required at least 6-hour exposure to 1.0 m NaHCO₃ to produce 99% lethality (decrease colony-forming units by 2 log₁₀), whereas selected periodontal pathogens were killed more rapidly (30–120 minutes). The higher the concentration of bicarbonate, the faster the lethality. Morphologic examination by transmission electron microscopy of organisms exposed to bactericidal salt concentrations revealed marked fibrillar condensations within the cytoplasm and shrinkage of the cytoplasm from the outer membrane. For NaHCO₃ to be clinically effective, a high concentration must be introduced into the periodontal pocket and maintained there long enough to kill periodontal pathogens. Furthermore, NaHCO₃ must be reapplied often enough to prevent recolonization by these pathogens. An advantage of NaHCO₃ over NaF, SLS and other antimicrobial agents is its safety, availability and low cost.     

Phenobarbital Adsorption from Simulated Intestinal Fluid,U.S.P., and Simulated Gastric Fluid,U.S.P., by Two Activated Charcoals

Adsorption of phenobarbital from simulated intestinal and gastric fluids by two activated charcoals was studied. Adsorption isotherm data were analyzed by the linearized Langmuir equation and by nonlinear least-squares regression employing both Langmuir and Freundlich models. These analyses indicated differences in the capacities of the two charcoals for phenobarbital which could not be completely explained by surface-area considerations.     

Multiple myeloma among Blacks and Whites in the United States: role of cigarettes and alcoholic beverages

In the United States, the incidence rates of multiple myeloma inBlacks are more than twice those in Whites, but the etiology of this canceris poorly understood. A population-based case-control interview study of 571subjects (365 White, 206 Black) with multiple myeloma and 2,122 controls(1,155 White, 967 Black) living in three areas of the United States (Georgia,Michigan, New Jersey) offered the opportunity to investigate the relationshipwith smoking and alcohol drinking and to evaluate whether these factors mightcontribute to the excess risk of multiple myeloma in Blacks. For Blacks andWhites of either gender, there were no significantly elevated risksassociated with ever use of cigarettes or alcoholic beverages and noconsistent patterns with either intensity or duration of use. These datasupport previous studies indicating that smoking and drinking are not relatedcausally to the risk of multiple myeloma, and thus cannot account for theracial disparity in incidence rates.