Search

Skirrow's medium is effective for isolating Campylobacters from human faeces but is less suitable for animal and environmental specimens owing to the presence of contaminating species. After determining the sensitivity of 104 strains of Campylobacters to several antimicrobial agents, used singly and in various combinations, a selective medium incorporating polymixin, rifampicin, trimethoprim and actidione, was developed. The medium, called Preston medium, was shown to be more selective than Skirrow's medium and suitable for any kind of specimen.

A survey was carried out to determine values for the prevalence and intensity of infection of intestinal helminths in children living in Cocle Province, Republic of Panama. The data set consisted of the results of microscopic examinations (modified Kato Katz technique) of stool samples collected in November 1987 from 661 children attending primary schools in 4 communities in the province. The overall prevalences of Ascaris lumbricoides, hookworm and Trichuris trichiura infections were found to be 18.2, 12.0 and 27.5% respectively. There were significant differences between the infection prevalence values for children attending the different schools, but not with respect to age or sex. Positive associations were detected between particular pairs of infections and these were most evident when Trichuris trichiura was involved. The data revealed evidence of a positive association between siblings at one school only for each helminth infection. There was extreme variation in the values for intensity of infection (20-126180 epg for A. lumbricoides). Highly significant, and unexplained, differences were observed in the intensity of A. lumbricoides infection by primary school; this finding did not apply to hookworm or T. trichiura. The analysis also revealed that children heavily infected with A. lumbricoides were also likely to be heavily infected with T. trichiura. Comparisons with the results of surveys carried out in Cocle Province in 1926 and 1974 indicate that these infections are declining in this region of Panama.

The utility of a rapid antigen test for diagnosing cases of persistent giardiasis, as defined by detection of cysts by conventional microscopy following standard formalin–ether concentration or the positive rapid antigen test, was investigated following a large, waterborne outbreak of giardiasis. The sensitivity and specificity of the rapid test as compared with microscopy were 60.7% and 96.7%, respectively, in this patient group. The low sensitivity contrasts with previous reports, and may be partly explained by low cyst numbers.

SUMMARYThe activity of the gluconeogenic enzyme, alanine-amino-transferase (ALT), in a preparation from the liver of rats was studied by means of anin vitroassay throughout the course of a primary infection ofNippostrongylus brasiliensis, established by a subcutaneous injection of approximately 4000 3rd-stage larvae. The activity was measured on days 1–14 p.i. in both uninfected and infected rats and a marked pattern in the enzyme's activity was observed. In infected rats, the activity increased from 1·46±0·19 U/g liver on day 1 p.i. to a peak on day 4 p.i. of 10·75±1·62 U/g liver, then decreased to a trough of 0·44±0·18 U/g liver on day 10 p.i. before returning to original levels by day 14 p.i., by which time the infection had been largely eliminated. In uninfected rats the activity of the liver enzyme remained constant throughout this period with a value of 2·54±0·12 U/g liver. The activity of the enzymein vitrowas found to be related to the size of the inoculum on days 4 and 10 p.i. It was proposed that these observations could be due to either (1) a direct effect of the parasite, or (2) a consequence of the host immune response to the infection. In order to investigate the second proposition more fully, liver ALT activity was investigated byin vitroassay on selected days p.i. in rats experiencing a secondaryN. brasiliensisinfection. In these rats the liver ALT activity was observed to reach a peak on day 2 p.i., with an activity of 3·87 ± 0-28 U/g liver, and a trough on day 4 p.i. with an activity of 0·11 ±0·03 U/g liver, returning to similar levels to those measured in uninfected rats by day 7 p.i. When serum prepared from rats having secondaryN. brasiliensisinfections collected on day 4 p.i. was added to the assay, a reduction in the activity of liver ALT activity from both the infected and uninfected rats was measured byin vitroassay. The results are discussed in relation to protein metabolism and gluconeogenesis in rats infected withN. brasiliensis, and also in relation to the host’s immune response to the parasitic infection.