A detailed bacteriologic study was done on 161 patients operated for appendicitis. Aerobic and anaerobic cultures were taken from the blood, the appendicular lumen, mucosa, serosa, fossa, and from the wound after closure of the peritoneum. There is no correlation between the degree of appendicitis and the incidence of positive blood culture. The infection spread through the appendicular wall as the disease progressed. Aerobic infection was common in early appendicitis but a mixed aerobic and anaerobic infection was predominant in late cases. Late appendicitis, a positive wound culture at the end of the operation, the duration of symptoms of over 36 hours before operation and the age of the patient over 50 years were all associated with an increased incidence of septic complication. From the antibiotic sensitivity on the bacteria isolated, the most effective agent against anaerobes was metronidazole. Effective agents against the aerobes were aminoglycosides and cephalosporins. The best single agent against both anaerobes and aerobes was moxalactum.

The accuracy of differential quantitative blood culture in the diagnosis of central venous catheter sepsis was evaluated in 24 parenterally-fed patients in whom catheter sepsis was suspected. The pour-plate quantitative culture technique was performed immediately before removal of the catheter on blood drawn through the central venous catheter and a peripheral vein. If bacterial colonies in the catheter blood specimen were sevenfold more frequent than identical bacterial colonies in the peripheral blood specimen, the test was considered positive and indicative of catheter sepsis. Catheter-tip culture identified 9 of the 24 patients as positive for catheter sepsis. A positive differential quantitative blood culture result was found for seven of the nine infected catheters. Sensitivity of this test was 77.8%, specificity was 100%, and overall accuracy was 91.7%. It is concluded that differential quantitative blood culture is a reliable method for the exclusion of catheter sepsis.

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The safety and efficacy of a single daily dose of netilmicin plus metronidazole after appendicectomy for gangrenous and perforated appendicitis was compared with the traditional thrice daily dosage. Twenty patients were enrolled in each group. The antibiotics were given intramuscularly for seven days after operation. Eradication of infection was observed in all patients and the postoperative wound sepsis was the same for each group. A significantly higher peak serum netilmicin level was achieved in the group receiving a single daily dose but nephrotoxicity was not observed. We concluded that the single daily dose of netilmicin was well tolerated and was as efficacious in this small series as the thrice daily regimen. The single-dose regimen has the advantage of simplicity and potentially increased bactericidal activity.

In a study of three socio-economic groups in Hong Kong, the high income group had a high faecal concentration of bile acids, especially the dihydroxy bile acids, compared to the low income group. The faecal bile acids were also more highly degraded. The faecal flora contained more bacteroides and fewer eubacteria. Very few of the clostridia able to dehydrogenate the steroid nucleus were isolated. An epidemiological study based on street blocks indicated that the high income group also have a higher incidence of cancer of the large bowel and of the breast. The results are discussed in terms of theories on the aetiology of large bowel cancer.

PLATES IV AND VD URING an investigation of Cryptococcus neoformans isolated from clinical specimens, we observed that growth of the fungus was considerably reduced in the vicinity of colonies of Pseudomonas aeruginosa. This phenomenon was first noted by Fisher (1954), who found that the inhibitory effect was exhibited only by living cultures of certain strains of P. aeruginosa. His efforts to isolate the inhibitor were unsuccessful and no further report on this phenomenon has since appeared. We report here a study of factors affecting the production of inhibitor by P. aeruginosa and an initial attempt to isolate and characterise the substances involved. MATERIALS AND METHODSStrains tested. Of 44 strains of P. aeruginosa tested for their inhibitory activity on C. neoformans, 11 (nos. 8, 10, 17, 26, 39, 52, l0/55, 8/39, 283, 577 and 584) were obtained from Dr M. T. Parker, Colindale, England; 13 (Gillies and Govan's type strains 1, 2, 3, 4, 5, 6, 7, 8 and A, By C, D, E) were obtained from the Public Health Laboratory, Edmonton, Canada; and 20 were freshly isolated from clinical specimens of wound and burn infections in Hong Kong. Fourteen strains of C. neoformans were tested for their sensitivity to the inhibitory effect of P. aeruginosa. These included 13 strains isolated from the cerebrospinal fluid of cryptococcal meningitis cases in Hong Kong and one strain, no. 1499.22, obtained from Dr Margarita Silva, Columbia University, NY, USA.The media used for this study were: Sabouraud Dextrose Agar (Oxoid), Tryptone Soya Agar (TSA, Oxoid), Diagnostic Sensitivity Test Agar (DST, Oxoid), and King's media A (without CuC12) and B. The latter two media were prepared according to the published formulae (King, Ward and Raney, 1954). Glucose was added to TSA, DST and the two King's media to final concentrations of 0.2, 0.5, 1.0, 2-0 and 3.0% to study its effect on the production of inhibitors.Methods for testing the inhibitory action of P. aeruginosa on the growth of C. neoformans. In preliminary studies, two methods were used to demonstrate the inhibitory effect. (1) By means of the technique described by Fisher (1954)' plates of TSA medium were initially lawned with C. neoformans, and after drying were inoculated centrally with P. aeruginosa (lower row, fig. 1). Small zones of inhibition were obtained. (2) With a method based on that described by Gillies and Govan (1966), P. aeruginosa from a 24-h broth culture was inoculated centrally in a circle of 1-cm diameter on TSA plates and incubated for 2 days. Growth was then removed, the residual cells were killed with chloroform vapour, and the surface of the plate was lawned with C. neoforrnans (top row, fig. 1). Zones of inhibition were larger, and it was apparent that inhibition did not depend on the presence of living P. aeruginosa.Media.

Indirect immunofluorescent and agglutination assay were used to study the anti-Candida albicans reactivities in the serum of 13 normal subjects and 14 patients infected with C. albicans. A significant increase in anti-C. albicans seroreactivity was observed during infection with this organism but the increase in the anti-germ tube immunofluorescence titre was the more marked. It is evident that the anti-germ tube immunofluorescence assay is more discriminatory for C. albicans infection than the conventional agglutination assay.

SUMMARYMost babies are colonized by the predominant strains of Escherichia coli present in their own mother's faecal flora. Those babies who did not acquire their maternal faecal flora acquired strains of E. coli belonging to a small number of the possible serotypes. Moreover, the same serotypes were found in several babies and other mothers, suggesting spread within the ward. These few strains included some of the 0 groups which had previously commonly been found as urinary pathogens. These strains may have increased potentialities for colonization of human bowel. Antigenic and biochemical variation was observed among the strains.