Following the Nipah virus (NV) outbreak in March 1999 in Singapore, a serological survey was undertaken to screen individuals potentially exposed to NV. Blood samples were tested for NV IgM, IgG and neutralizing antibodies. Twenty-two (1.5%) of 1469 people tested had antibodies suggesting NV infection. Although 12 of the 22 infected people (54.6%) were symptomatic, the remaining 10 (45.4%) were clinically well and had no past history of compatible pulmonary or neurological disease. Clinical and serological findings suggested three people had been infected with NV before the outbreak was recognized. All those who were infected were male abattoir workers. None of the people who had contact with horses, and no healthcare workers exposed to infected patients and their specimens had detectable antibodies. This study provides evidence that NV causes asymptomatic infection. All of the antibody positive individuals had direct contact with pigs and there was no evidence of human to human transmission.

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SUMMARY In a study of 13 local and four reference strains of Haemophilus ducreyi all grew well on a selective medium consisting of Bacto proteose No 3 agar (Difco), soluble starch, IsoVitalex, human blood, and vancomycin. All the strains reduced nitrate, were alkaline-phosphatasepositive, and (with one exception) used glucose, fructose, and mannose. P-lactamase was produced by 12 local strains. Erythromycin was the most effective antibiotic tested, followed by streptomycin, co-trimoxazole, and spectinomycin.

The 2.6-megadalton (MDa) cryptic plasmid and the 4.4-MDa beta-lactamase plasmid of Neisseria gonorrhoeae were radiolabeled with [32P] nucleotides and used as probes for direct detection of gonococci and beta-lactamase plasmids in urethral exudates from men with urethritis. The sensitivity and specificity of the DNA probes were compared with culture isolation of N. gonorrhoeae and biochemical tests of gonococcal isolates for beta-lactamase production. Of 216 urethral specimens, 180 were positive for N. gonorrhoeae by DNA probe and culture, 27 were negative by both tests, and 9 gave discordant results. Compared with culture and with the chromogenic cephalosporin assay, the sensitivity and the specificity of the DNA probe was 99% and 93% and that of the beta-lactamase probe assay was 91% and 96%, respectively. Electrophoresis of plasmids isolated from 90 gonococcal cultures showed that all contained the 2.6-MDa plasmid, 29 possessed a 3.2-MDa plasmid, 18 a 4.4-MDa beta-lactamase plasmid, and 11 had a 24.5-MDa conjugal plasmid. We conclude that the sensitivity of our DNA probes was comparable to that of culture for diagnosis of gonorrhea and to conventional tests for detection of beta-lactamase.

SummaryOne hundred and seventy-eight samples from 168 individuals were tested for Mycobacterium tuberculosis complex (Mtc) using Amplicor PCR, IS6110-PCR (in-house), acid fast (AF)-staining and culture. Thirty-one samples were positive by culture, but 37 samples were later resolved to be truly positive for Mtc. Of these, Amplicor detected 32 (86.5%), IS6110-PCR detected 31 (83.6%), and AF-staining 21 (56.8%). None of the 141 Mtc-negative samples was positive by these tests, thus giving 100% specificity. Although the IS6110-PCR was more sensitive than Amplicor in detecting spiked Mtc DNA, it was not more sensitive than the latter in detecting Mtc in clinical samples. Reasons likely to account for the PCR false negativity were (i) sample inoculum size, (ii) nonuniform samples due to clumping effect of Mtc and (iii) the absence of target gene sequences for IS6110-PCR. Culture negativity, on the other hand, was likely to be associated with nonviable Mtc. Amplicor PCR is promising for direct detection of Mtc. The IS6110-PCR, however, may not be as suitable because of possible existence of IS6110-deleted Mtc strain in Singapore.