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Biomedical subjects

P R Sisson

Publications and source records attributed to P R Sisson.

At least 55 records · Page 3Linked to original sources

Five days versus one day of penicillin as prophylaxis in elective neurosurgical operations.

Of 423 patients undergoing elective cranial and spinal operations, infections due to Staphylococcus aureus occurred in 3 of 217 (1.4%) receiving penicillin for 1 day, in none of 206 receiving penicillin for 5 days. There was no significant difference in rates of infection between the two groups receiving penicillin. It is concluded that penicillin for 1 day is as effective as penicillin for 5 days, in the prevention of wound infections due to S. aureus.

Adult↗

Bacteriology of chronic otitis media with effusion.

Samples of middle ear effusions from 102 children with serous and mucoid otitis media were cultured for mycoplasmas and bacteria. No sample yielded mycoplasmas but bacteria were cultured from 48 (47 per cent). Organisms commonly regarded as pathogens were present in 25 samples (Haemophilus influenzae 17, Streptococcus pneumoniae four, other streptococci four). The only sample from which anaerobic bacteria were isolated was from a patient with cholesteatoma.

Bacteria↗

Twelve-hourly dosage schedule for oral and intravenous metronidazole.

Paired samples of blood were examined from 48 patients undergoing major surgery who were receiving metronidazole at a 12-hourly dosage interval, as part of a regimen for prophylaxis or therapy. Twenty-five patients were given 400 mg metronidazole orally twice a day and 23 received 500 mg metronidazole iv twice daily. Assay of the samples demonstrated trough serum concentrations of metronidazole of 3-11 mg/l (mean 5.5 mg/l) and 2-15 mg/l (mean 6.7 mg/l) with the oral and intravenous routes, respectively. The corresponding peak serum concentrations were 10-26 mg/l (mean 17.4 mg/l) and 13-28 mg/l (mean 23.6 mg/l). The trough concentrations are well in excess of the MICs for the majority of obligate anaerobes and thus the 12-hourly regimen achieves and maintains therapeutic serum concentrations of metronidazole.

Administration, Oral↗

Simple peroperative antimicrobial chemoprophylaxis in elective neurosurgical operations.

From August 1981 to February 1982 postoperative infections due to different strains of penicillin-resistant Staphylococcus aureus occurred in 20 of 467 patients (4.3%) undergoing elective cranial and spinal operations. These infections were not attributable to defects in procedures or the theatre environment, therefore chemoprophylaxis was instituted. In the following 8 months, when patients were given penicillin G and sulphadiazine for 5 days commencing immediately postoperatively, S. aureus infections occurred in five of 579 patients (0.9%). In a subsequent randomized uncontrolled study, infections occurred in six of 265 patients receiving penicillin (2.3%), three of 270 receiving penicillin and sulphadiazine (1.1%) and one of 45 receiving erythromycin (2.2%) immediately postoperatively for 5 days. In a further study in which 587 patients received penicillin for 5 days commencing immediately preoperatively, infections due to S. aureus occurred in six (1.1%). Infections due to gram-negative organisms were seen in five (0.4%) of 1167 patients in the two uncontrolled studies.

Drug Therapy, Combination↗

Carbon dioxide laser irradiation of bacterial targets in vitro.

Agar targets seeded with Escherichia coli and Staphylococcus aureus in roll tubes simulating the vaginal vault were irradiated with a CO2 laser at various power densities and durations. Viable bacteria were detected in the plume emissions in all instances. Staphylococcus aureus was found to be more resistant to the thermal effects of lasing than E. coli. This suggests that CO2 irradiation of cervical lesions could disseminate viable particles which may be a hazard for patients and operators.

Air Microbiology↗

Wise Anaerobic Work Station: an evaluation.

The Wise Anaerobic Work Station permitted the growth of type cultures of a range of fastidious obligate anaerobes. In the isolation of anaerobic bacteria from clinical specimens the performance equalled that of a standard anaerobic jar incubated for 48 hours, and gave results superior to those obtained when incubation of jar cultures was interrupted at 24 hours. The Wise Anaerobic Work Station was easy to use and provided comfortable working conditions; running largely on industrial nitrogen, it was more economic than anaerobic cabinets or jars using conventional gas mixtures.

Bacteria, Anaerobic↗

Pathogenic synergism.

Microbial synergy is well recognized but its role in the pathogenesis of human infections is poorly understood and probably underestimated. Recent experiments with animal models and in vitro studies should facilitate a more objective and critical assessment of the contribution to various infections by microorganisms, individually and collectively.

Actinomycosis↗

Characteristics of motile curved rods in vaginal secretions.

Motile curved rods seen in vaginal secretions have been isolated on Columbia agar supplemented with 5% human blood and vitamin K. Growth occurred anaerobically and in 5% oxygen but not in more aerobic conditions. There were two distinct groups of these organisms, distinguishable by morphology, biochemical activity and susceptibility to metronidazole. All isolates were sensitive to a wide range of antimicrobial agents, with the exception of nalidixic acid and polymyxin, but one group was resistant to metronidazole. There was little difference between the results of tests of susceptibility to aminoglycosides or to metronidazole performed in anaerobic and microaerophilic conditions. Motile curved rods were isolated from 18 of 80 patients with a clinical diagnosis of non-specific vaginitis, but from only two of 39 without the disease.

Anti-Bacterial Agents↗

Phagocytosis and killing of bacteria in aerobic and anaerobic conditions.

Phagocytosis and intracellular killing of several facultative anaerobes were observed in aerobic and anaerobic conditions. The presence of anaerobes affected these processes. Bacteroides asaccharolyticus and B. fragilis were killed by phagocytes only at bacterial concentrations less than 1 x 10(7) cfu/ml; at higher concentrations of the anaerobes, killing of B. fragilis and concomitant facultative anaerobes was inhibited. This effect appeared to be due to an interaction, in appropriate reducing conditions, between anaerobe and serum, which allowed engulfment of organisms by phagocytes but markedly impaired intracellular killing.

Aerobiosis↗