A crude extract of Escherichia coli 013:K92:H4 inhibited 97% of positive indirect immunofluorescence titers against a variety of gram-negative bacterial antigens while lowering Legionella pneumophila titers in only 6% of sera from patients with suspected legionellosis. Legionella-specific titers were the result of immunoglobulins G, M, and A, singly or in combination.

Sera from six outbreaks of legionellosis and four outbreaks of pneumonia of other etiologies were tested with the indirect immunofluorescence assay (IFA) as currently performed. The current IFA is at least as sensitive as the original test in detecting cases of Legionnaires disease (78 to 91%). By using Center for Disease Control criteria for a positive (fourfold increase in titer during convalescence to-128) or presumptive (single titer-256) serological test, the specificity exceeded 99%. No cross-reactions against Legionella pneumophila antigens were observed among sera from epidemic cases of Q fever, tularemia, and psittacosis; the only positive L. pneumophila IFA titer among the epidemic Mycoplasma pneumonia sera was reduced to a negative titer with an immunosorbent extracted from Escherichia coli strain 013:K92:H4. The slight increase in specificity (to 100%), however, was offset by a slight decrease in sensitivity. The sensitivity of the IFA was maximal when a conjugate that detected immunoglobulin G, M, and A was used. IFA titers were not significantly altered by replacing the monovalent serogroup 1 antigen with a polyvalent antigen (serogroups 1 through 4) nor by the presence of rheumatoid factor or heat-labile serum factors.

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The hyaluronate lyase (hyaluronidase) gene from Propionibacterium acnes was cloned and sequenced. The gene was isolated on an EcoRI-generated 3-kb piece of DNA. Expression was less in Escherichia coli than in P. acnes; in E. coli, active enzyme was only cell associated and not secreted. The gene is 2256-pb long and codes for a protein of 82 kDa. Amino terminal sequencing of the protein of the partially purified gene indicated the presence of a 32-amino-acid leader sequence. The leader sequence showed a membrane-spanning domain and all of the features usually associated with the leader for a secreted protein. The amino acid sequence is predicted to share homology with the hyaluronidase enzymes from Streptococcus pneumoniae, Streptococcus agalactiae, and Staphylococcus aureus. A potential hyaluronate-binding domain was identified and antibody against this domain was inhibitory to the enzyme.

We obtained a catalase-deficient (Kat-) strain of Neisseria gonorrhoeae isolated from a patient who had been unsuccessfully treated with penicillin. Quantitative enzyme assays and electrophoresis of cell extracts on native polyacrylamide gels subsequently stained for catalase and peroxidase activities failed to detect both enzymes.The strain exhibited no growth anomalies or unusual requirements when grown under ordinary laboratory conditions. However, the Katstrain proved extremely sensitive to exogenous hydrogen peroxide, and analysis of the bacterial DNA after such exposure showed extensive single-strand breakage in both chromosomal and plansmid DNAs. Partial characterization of the gonococcal catalase from a Kat+ laboratory strain revealed that the enzyme had the physical and chemical properties of both catalase and peroxidase.