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Biomedical subjects

M T Kelly

Publications and source records attributed to M T Kelly.

11 recordsLinked to original sources

Antimicrobial susceptibility testing of Mycobacterium fortuitum complex.

A total of 24 strains of the Mycobacterium fortuitum complex were tested for susceptibility to antimicrobial agents by the disk diffusion and agar dilution techniques. By comparing zones of inhibition obtained with the disk diffusion technique with results of minimal inhibitory concentration determinations, it was shown that disk diffusion results could predict in vitro susceptibility to selected antimicrobial agents. All of 17 strains of M. fortuitum were susceptible to </=1 mug of amikacin per ml. The corresponding average zone of inhibition around a 10-mug amikacin disk was 37 mm. Seven M. chelonei strains were more resistant to amikacin, with minimal inhibitory concentrations ranging from 1 to 32 mug/ml, and the corresponding average zone size was 21 mm. Susceptibility of both M. fortuitum and M. chelonei to tetracycline was variable and none of the M. chelonei strains was inhibited by polymyxin B, whereas M. fortuitum strains consistently had zones of inhibition around the polymyxin disk. It appears that identification to species of the M. fortuitum complex may be of importance with regard to antibiotic susceptibility. Separation of M. fortuitum and M. chelonei was readily accomplished in the present study by the nitrate reduction and 3-day arylsulfatase tests.

Aminoglycosides

Sputum screening by Nomarski interference contrast microscopy.

Gram-stained smears of specimens submitted for sputum cultures were compared with direct wet mounts examined by Nomarski interference contrast microscopy (NIM) for enumeration of squamous epithelial cells (EPC) and leukocytes (WBC). The results obtained by the two methods were comparable, but specimens were more rapidly screened and cell types were more readily differentiated by NIM. Specimens submitted for sputum culture over a 3-month period were examined for EPC and WBC by NIM. Twenty-two percent of the specimens had greater than 25 EPC/field or a predominance of EPC (class I), 30% had greater than 25 EPC and greater than 25 WBC/field (class II), and 48% had greater than 25 WBC/field or a predominance of WBC (class III). The clinical relevance of the culture results was determined by reviewing the records of patients whose specimens were included in the study. Class I specimens provided only 30% clinically relevant culture results. Specimens in class II provided useful culture results in 63% of the patients, and 96% of those in class III provided clinically relevant information. The results confirm the value of sputum screening and demonstrate that NIM provides a rapid, simple, and accurate method for sputum screening.

Diagnosis, Differential

The value of sonography in suspected ectopic pregnancy.

Of 356 women undergoing sonography to diagnose or rule out an ectopic gestation, data sufficient to assign a final diagnosis were available on 260 of them. Ectopic gestation was diagnosed in 25 cases in this group and intrauterine pregnancy in 99, while the remaining 136 patients were found not to be pregnant. During sonography, ectopic gestations were suspected or diagnosed in 27 instances: In 17 cases this was in agreement with the final diagnosis, but neither an intrauterine nor an extrauterine gestation existed in 10 cases, although neoplastic or inflammatory masses were present. Of the 25 patients with the final diagnosis "ectopic pregnancy," this was not detected with sonography in 8 instances. Intrauterine pregnancies were diagnosed by sonar in 94 of the 99 cases. Although reliable sonar identification of ectopic gestation is not always possible, sonography is helpful in diagnosing intrauterine pregnancy so that surgical intervention can be avoided.

Adolescent

Plasma-dependent chemotaxis of macrophages toward BCG cell walls and the mycobacterial glycolipid P3.

BCG cell walls, associated with oil droplets in the form of emulsions in saline, generate macrophage chemotactic activity from fresh guinea pig plasma. Serum and heat-inactivated plasma were inactive, suggesting involvement of complement or fibrinogen-derived chemotactic factors. Suspensions of cell walls and oil droplets each generated chemotactic activity from plasma, and the activity of the cell wall vaccine was due to the additive effects of these two components. A mycobacterial glycolipid (P3), which is a constituent of BCG cell walls, also had plasma-dependent chemotactic activity. The results suggest that macrophage chemotaxis may be an important part of the immunopotentiating activity of these mycobacterial products.

Animals

Immunotherapy with nonviable microbial components.

Structural components of microorganisms have been studied for immunopotentiating effect with the aid of transplantable (line 10) tumors in syngeneic guinea pigs. Microbial components were associated with oil droplets, suspended in Tween-saline, and injected intralesionally. BCG cell walls, given in this way, produced regression and cure of 50-60% of established tumors, as did viable BCG. Lipid extraction markedly reduced the tumor-regressing potency of cell walls, but P3, a trehalose mycolate present in the extract, restored full activity to the cell wall residue. P3 alone was nonsensitizing and had no antitumor activity, but it enhanced the latter property of various other microbial products. For example, the cure rates produced by cell walls of M. tuberculosis, M. bovis, M. phlei, or M. smegmatis were enhanced from 20-60% to as much as 90% by addition of P3. P3 also conferred antitumor activity on products from unrelated microbes, such as cell walls of E. coli, and in combination with endotoxins from rough Re mutant salmonellae, it produced cure rates of up to 93%. These results suggest that P3 is essential to the immunopotentiating activity of mycobacteria and that it may be broadly applicable in immunotherapy of cancer with microbial agents.

Animals