A polymerase chain reaction (PCR) for the specific detection of Helicobacter pylori was developed with a single primer pair derived from the nucleotide sequence of the urease A gene of H. pylori. We achieved specific amplification of a 411-bp DNA fragment in H. pylori. After 35 cycles of amplification, the product could be detected by agarose gel electrophoresis and contained conserved single HinfI and AluI restriction sites. This fragment was amplified in all 50 strains of H. pylori tested, but it was not detected in other bacterial species, showing the PCR assay to be 100% specific. PCR DNA amplification was able to detect as few as 10 H. pylori cells. PCR detected H. pylori in 15 of 23 clinical human gastric biopsy samples, whereas culturing and microscopy detected H. pylori in only 7 of the samples found to be positive by PCR. Additional primer pairs based on the urease genes enabled the detection of H. pylori in paraffin-embedded human gastric biopsy samples. The detection of H. pylori by PCR will enable both retrospective and prospective analyses of clinical samples, elucidating the role of this organism in gastroduodenal disease.

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Summary.The clinical importance of the gram-positive anaerobic cocci (GPAC) isolated in 1987 at St Bartholomew's Hospital, London, is assessed. Of about 800 anaerobic isolates, 209 (27 YO) were GPAC, of which 67 (32%) were from abscesses and 22 (11 YO) were in pure growth. Four species comprised 77% of the 168 isolates available for study: Peptostreptococcus magnus (55 isolates, 33 YO), P. micros (23, 14 YO), P. asaccharolyticus (24, 14 Yo) and P. anaerobius (27, 16 YO). Different species were associated with different sites, from P. magnus (usually skin-associated sites ; normally cultured with aerobes, infrequently with other anaerobes), P. asaccharolyticus (distributed widely) and P. anaerobius (usually genitourinary and gastrointestinal; always below the diaphragm) to P. micros (always deep sites with other anaerobes). P. magnus was isolated from 15 abscesses and was obtained in pure culture from 11 specimens, six of them abscesses developing from infected sebaceous cysts. P. micros was usually isolated from soft tissue abscesses, never from the skin, and with a characteristic mixed flora consisting of " Streptococcus milleri" and anaerobic gram-negative rods. P. heliotrinreducens was a rare isolate from similar specimens. P. asaccharolyticus was cultured from a wide variety of sites, typically mixed with both aerobes and anaerobes, and frequently from abscesses. Most isolates of P. anaerobius came from gastrointestinal or female genitourinary specimens, never from above the diaphragm and rarely from the skin; cultures were usually heavily mixed. Isolates of P. vaginalis and the " bGAL" group made up 11 YO of strains and were usually cultured from superficial sites, P. vaginalis often from post-operative wound infections with Staphylococcus aureus. There were only two isolates of P. hydrogenalis, three of P. tetradius and none of P. barnesae, P. prevotii, P. lacrimalis, P. lactolyticus, P. productus or Peptococcus niger. GPAC are a heterogeneous group associated with a wide variety of infections, particularly abscesses, and are frequently isolated in pure culture. They deserve further study.

A polymerase chain reaction for the specific detection of Helicobacter pylori was developed using a primer pair derived from the nucleotide sequence of the urease A gene of H pylori. Specific amplification of a 411 base pair DNA fragment from all strains of H pylori tested was achieved. Ten organisms were detected using the PCR and the technique permitted direct detection of H pylori in clinical biopsy samples. PCR will be useful for both prospective and retrospective investigation of the aetiology and epidemiology of H pylori associated disease.

A tetracycline resistance (Tc') determinant from Closfridium &Bile strain 630 was cloned into the Escherichia coli plasmid vector pUC13. The resulting plasmid pPPM20, containing an insert of 3.4 kbp, was mapped and a 1.1 kbp SucI-Hind111 fragment wholly within the Tcr gene was identified. Dot-blot hybridization studies with the 1.1 kbp fragment showed that the Tcr gene belonged to hybridization class M. Tcr could be transferred between C. &mile strains and to Bacillus subtilis at a frequency of lo-' per donor cell. The element could be returned from B. subtilis to C. &@cik at a frequency of per donor cell. This is the first demonstration of C. &Wile acting as a recipient in intergeneric crosses. DNA from C. dzBcile transconjugants digested with EcoRV always has two hybridizing fragments of 9.5 and 11.0 kbp when probed with pPPM20. DNA from B. subtiZis transconjugants digested with EcoRV produced one hybridizing band of variable size when probed with pPPM20. The behaviour of the element was reminiscent of the conjugative transposons. Therefore we compared the element to the conjugative transpomn Tn916. The Him11 restriction maps of the two elements Mered and no hybridization was detected to oligonucleotides directed to the ends of Tn916. However, the elements do have some sequence homology, detected by hybridization analysis.

Candidal antigens were isolated by affinity chromnatography from the sera of patients with disseminated Candida albicans infections. The immunodominant 47-kilodalton (kDa) antigen appeared to be a heat-stable breakdown product of several larger heat-labile compQnents (84 to 92, 74 to 79, and 66 to 72 kDa). It was undetectable in normal sera and sera from four patients with systemic C. parapsilosis, C. tropicalis, and C. krusei Infections. Serum samples from 92 patients with proven systemic C. albicans infections were examined by the immunoblot technique. Seventy-four patients h4d detectable antibody, and 92% of these produced antibody to the 47-kDa antigen. All survivors had major serological responses to this antigen, whereas patients who died had no, minor, or fading responses. Fifty-five of the patients were neutropenic following cytotoxic chemotherapy for malignancies, usually lymphoproliferative disorders (hematological patients). The remainder were surgical or medical patients (nonhematological). Hematological patients differed from nonhematological patients in the range of antigens that were commonly recognized by their immune systems, although antibodies to the 47-and 60-kDa antigens were frequently present in both groups. They also differed in that they produced mainly an immunoglobulin M (IgM) response, failing to seroconvent to IgG. This did not reduce survival rates, which were similar in both groups. It may be responsible, however, for the lower antigen titers that were observed in hematological patients when measured by reverse passive latex agglutination.