An analysis of blood culture isolates from 7 South African teaching hospital centres

The data on blood culture isolates for 1983 and January - July 1984 reported by the Antibiotic Study Group of South Africa have been analysed to determine national and regional prevalences of different micro-organisms and resistance to certain antibiotics. Although there are significant differences in isolation frequencies between the various centres, overall the five most frequent isolates are Staphylococcus aureus (1983 - 15%; 1984 - 14%), Escherichia coli (13%), Klebsiella spp. (11%; 10%), Streptococcus pneumoniae (9%), and Salmonella typhi (7%; 13%). Staph. aureus ranks first in most centres for 1983 but is displaced in some in 1984 by enteric Gram-negative bacilli. In Durban S. typhi is the most common isolate for the entire period. Methicillin resistance among Staph. aureus is common (approximately 30% overall), especially in the Transvaal. Gentamicin resistance among certain Gram-negative bacilli is a problem in many centres and is especially disturbing in the case of Klebsiella spp., of which over 30% of total isolates are resistant. Ampicillin resistance for Haemophilus influenzae varies from nil to over 30% in different centres, and penicillin-resistant pneumococci are still encountered (nil to over 10%).

Antibody response to somatic antigen of Salmonella typhi in areas endemic and non-endemic for typhoid fever

In sera obtained between the 6th and the 30th day from 16 Austrian and 26 Hong Kong patients with culturally verified typhoid fever, agglutinating antibodies (microagglutination test) at significant titers were detected in 93% of the Austrian (median titer: 640) but in only 50% of the Hong Kong patients (median titer: 240). Similar results (93% and 54% positive sera respectively) were obtained for specific IgM as assessed by the enzyme-linked immunosorbent assay (ELISA) using lipopolysaccharide of S. typhi as antigen (median relative titer: 0.32 and 0.21 respectively). In contrast, specific IgG at significant concentrations were found in only 69% of the Austrian (median relative titer: 0.16) but 88% of the Hong Kong sera (median relative titer: 0.71). The (IgM-detecting) microagglutination test may be sufficiently diagnostic for typhoid fever in nonendemic areas such as Austria. In endemic regions like Hong Kong, however, tests indicative for early specific IgG are indispensable for serological diagnosis of the disease. The ELISA proved useful and is an example for such tests.

Hygienic hand disinfection

The purpose of hygienic hand disinfection is to render hands safe after contact with pathogens. Comparing effects of disinfection procedures on infection ratios is too difficult for routine purposes but the degerming efficacy may be determined in laboratory tests with volunteers. In the Vienna test model the efficacy of a specific procedure being tested is compared to that of a standard disinfection (rubbing into hands 3 ml of isopropanol 60% v/v, 30 seconds, twice) tested in parallel with the same volunteers. This ensures standardization, thus comparability of results between laboratories, and provides the investigator with a yardstick for efficacy. The model includes artificial contamination, assessment of the release of test bacteria (E. Coli ATCC 11229) before and after disinfection by the finger tip method, and addition of neutralizers to sampling fluids. Alcohols in appropriate concentrations are highly effective (log reductions: greater than 4.0) whereas procedures employing disinfectant detergents act like soap (log reductions: less than or equal to 3.2) and may cause dissemination of pathogens.