Limulus amoebocyte lysate assay in the diagnosis of peritonitis in patients receiving continuous ambulatory peritoneal dialysis.

AIMS: To evaluate the Limulus amoebocyte lysate (LAL) assay for differentiating Gram positive from Gram negative peritonitis in patients receiving continuous ambulatory peritoneal dialysis (CAPD). METHODS: One hundred and six patients with suspected peritonitis were studied. LAL assay was performed by adding 0.1 ml of CAPD fluid to 0.1 ml of LAL reagent and incubating in a heating block for 60 minutes at 37 degrees C. The sensitivity of the reaction was determined by: (i) diluting endotoxin in distilled water and used (filter sterilised) peritoneal dialysis fluid; and (ii) diluting a broth culture of E coli used in peritoneal dialysis fluid. A positive LAL assay was defined as the constant stability of the clot through an inversion of 180 degrees. RESULTS: Compared with bacterial culture, the LAL assay had a sensitivity of 65% and a specificity of 98%. The sensitivity of microscopy compared with culture of Gram negative organisms was 76%; overall sensitivity of microscopy in comparison was 80%. CONCLUSIONS: The Gram stain was more sensitive than has previously been reported; the LAL assay was specific but insensitive for the diagnosis of CAPD peritonitis. There was a correlation between reduced leucocyte count and culture; this was reduced in cases from which Gram negative organisms had been isolated. It is recommended that laboratories evaluate their Gram stain procedure to improve its sensitivity because the LAL assay is not a satisfactory substitute.

Potentiation of murine cytomegalovirus pneumonitis by antibiotics in clinical use.

Nineteen antibiotics were screened for their effects on the proliferation of murine spleen cells in vitro. Ketoconazole suppressed lymphoproliferation at clinically-attainable concentrations, whilst tetracycline, cephalothin, rifampicin and ciprofloxacin were also inhibitory at relatively low concentrations. These antibiotics were selected for further study. High concentrations of cephalothin inhibited macrophage uptake of colloidal gold, while spleen cells from mice treated with ketoconazole responded poorly to mitogenic stimulation in vitro. Humoral responses to ovalbumin, polyvinylpyrrolidone and murine cytomegalovirus (MCMV) were not suppressed by oral administration of ketoconazole, tetracycline, cephalothin, rifampicin or ciprofloxacin to mice. However, MCMV-infected mice receiving these antibiotics had increased virus loads and a greater persistence of virus and interstitial pneumonitis in their lungs. This was observed with clinically-attainable serum concentrations of cephalothin, tetracycline and ciprofloxacin. The findings warrant further investigation as the antibiotics are used to control secondary infections in immunosuppressed patients, many of whom experience cytomegalovirus disease.

Mycobacterium terrae tenosynovitis.

Atypical mycobacteria causing extra-pulmonary disease in man are well documented. These infections are manifested by the presence of ulcers, abscesses and lymphadenitis. Mycobacterium marinum is particularly noted for infections involving the synovium, tendon sheaths, bursae and bone. Of lesser note is Mycobacterium terrae (radish bacillus), a nonchromogen also associated with tenosynovitis. We are not aware of any previous report of the association of M. terrae with synovitis in Australia. This case report describes a culture-proven case of tenosynovitis caused by M. terrae.

Vertebral osteomyelitis due to Staphylococcus warneri.

We report a case of vertebral osteomyelitis in a diabetic woman. This appears to be the first report of such an infection with the coagulase negative staphylococcus, S warneri.

Chronic osteomyelitis due to Clostridium difficile.

Osteomyelitis caused by anaerobic bacteria is rarely reported, and a case of chronic osteomyelitis of the femur may be the first in which Clostridium difficile was the causative agent. The organism was isolated over several months and, although initially sensitive to penicillin, it developed resistance during this time. The organism's repeated isolation may have been due to the presence of resistant spores. Although the patient had no gastrointestinal symptoms the source of the organism was probably the patient's own gastrointestinal tract. Infection from the environment cannot, however, be excluded. Treatment was finally successful with metronidazole.

Serodiagnosis of human strongyloidiasis by an enzyme-linked immunosorbent assay.

The sensitivity specificity of an enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of strongyloidiasis has been investigated. 45 men with long-standing strongyloidiasis were compared with the same number of age- and sex-matched control subjects. The ELISA detected antibody in 84% of patients with parasitologically proven strongyloidiasis. When the technique was compared with an indirect immunofluorescent assay (IFA), a high correlation coefficient was obtained. Specificity was demonstrated by observing a marked fall in optical density of pooled positive serum after prior incubation with Strongyloides ratti soluble antigen but not after incubation with antigens derived from Ascaris suum or Dirofilaria immitis. The test is simple and offers a useful method for the diagnosis of strongyloidiasis. In these patients it was more reliable than a single parasitological examination of faeces or duodenal contents.

Systemic vibriosis due to non-cholera vibrio.

A case of extraintestinal vibriosis with septicaemia due to a non-cholera vibrio, from which the patient had recovered, is presented. Diagnostically useful clinical and laboratory data are described together with an outline of the combined medical and surgical treatment regimen which is employed. The association with excessive alcohol consumption and liver diseases is noted.