Bacteriophages, viruses that only kill specific bacteria, are receiving substantial attention as nontraditional antibacterial agents that may help alleviate the growing antibiotic resistance problem in medicine. We describe the design and preclinical development of AB-SA01, a fixed-composition bacteriophage product intended to treat Staphylococcus aureus infections. AB-SA01 contains three naturally occurring, obligately lytic myoviruses related to Staphylococcus phage K. AB-SA01 component phages have been sequenced and contain no identifiable bacterial virulence or antibiotic resistance genes. In vitro, AB-SA01 killed 94.5% of 401 clinical Staphylococcus aureus isolates, including methicillin-resistant and vancomycin-intermediate ones for a total of 95% of the 205 known multidrug-resistant isolates. The spontaneous frequency of resistance to AB-SA01 was ≤3 × 10−9, and resistance emerging to one component phage could be complemented by the activity of another component phage. In both neutropenic and immunocompetent mouse models of acute pneumonia, AB-SA01 reduced lung S. aureus populations equivalently to vancomycin. Overall, the inherent characteristics of AB-SA01 component phages meet regulatory and generally accepted criteria for human use, and the preclinical data presented here have supported production under good manufacturing practices and phase 1 clinical studies with AB-SA01.

Improved methods are needed for field diagnosis of onchocerciasis, to support efforts aimed at elimination of the disease. A rapid-format card test was evaluated that detects IgG4 antibodies to recombinant Onchocerca volvulus antigen Ov16 with serum samples from patients with onchocerciasis and with various types of control serum samples. The sensitivity of the test with serum samples from 106 microfilariae-positive subjects was 90.6%. The test was equally sensitive with serum samples obtained from patients in Africa and Latin America. Specificity was excellent; positive tests were observed for 2 of 38 serum samples from patients with other filarial infections and for 1 of 23 serum samples from patients with nonfilarial helminth infections. The 3 "false-positive" serum samples were from West Africans who could have been coinfected with onchocerciasis. No positive tests were observed with nonendemic serum samples from normal adults, patients with autoimmune disorders, or patients with the hyper-IgE syndrome. This new test holds great promise as a simple tool for diagnosis of onchocerciasis.

Forty three koalas in a captive colony were investigated for the presence of Chlamydia psittaci infection and associated disease. Swabs were taken from conjunctivae and urogenital sites for cell culture isolation of C psittaci and for cytological examination (direct smears) for chlamydial inclusions and evidence of inflammation. On the basis of cell culture isolation, 28 samples from 25 koalas were positive for C psittaci (that is, infected). Three koalas were positive from both sites, 5 from conjunctivae alone and 17 from urogenital sites alone. Seven of the 8 koalas with positive conjunctival swabs had overt signs of conjunctivitis, but only 3 of the 20 koalas with positive urogenital swabs had overt signs of 'wet bottom' (continual urine soiling due to cystitis) or purulent discharge. However, 5 of the 20 with positive urogenital swabs had past episodes of 'wet bottom'. Moreover, examination of direct cytological smears showed evidence of inflammation (neutrophils) in 7 of 8 koalas with positive conjunctival swabs and 17 of 20 with positive urogenital swabs. Chlamydial inclusions were rarely identified with surety on direct cytological smears. In the 18 koalas without chlamydia, one had overt conjunctivitis while 2 had past episodes of conjunctivitis. The koala with conjunctivitis at the time of sampling had a prior history of 'wet bottom'. Examination of direct cytological smears revealed 2 of the chlamydial negative koalas had high numbers of neutrophils in urogenital smears. It was concluded that C psittaci infection may cause overt or sub-clinical disease, with the former developing when the koalas were stressed through management procedures or concomitant disease.

SUMMARY An immune dot blot test (IDBT) to detect the genus specific lipopolysaccharide chlamydial antigen is described, in which the antigen is trapped on nitrocellulose membrane and then detected with a monoclonal antibody labelled with`25iodine. A preliminary comparison of 270 specimens obtained from the endocervix or male urethra showed that the IDBT was more sensitive (sensitivity 90%) than a commercial amplified enzyme immunoassay named IDEIA (sensitivity 60%) for detecting specimens that yielded Chlamydia trachomatis on culture. Subsequent assessment of 950 urogenital tract specimens in the IDBT and by culture confirmed the sensitivity (92%) and specificity (95%) of the IDBT. At least one of 56 specimens obtained from the eye, however, gave a false positive result, which was probably due to staphylococcal protein A in the specimen. The IDBT provides the basis for a novel simple test for detecting the genus Chlamydia. We describe a simple alternative method for immunological detection of C trachomatis, in which the genus specific lipopolysaccharide antigen' is trapped on nitrocellulose membrane and then detected by autoradiography with a radiolabelled genus specific monoclonal antibody. This immune dot blot technique compared well with conventional culture in its sensitivity, and with a currently available commercial ELISA kit, which uses the same monoclonal antibody, in its convenience. As the lipopolysaccharide antigen is found in all members of the Chlamydia genus, this technique may also be useful for diagnosing human respiratory infections caused by recently described atypical Chlamydia psittaci organisms,6 as well as in veterinary medicine. Materials and methods CLINICAL MATERIALWe assessed specimens submitted to the North Manchester Regional Virus Laboratory (NMRVL) for routine diagnosis of C trachomatis infection. Most material consisted of endocervical swabs from women and urethral swabs from men who attended the genitourinary medicine (GUM) clinic at the Manchester Royal Infirmary.

The sensitivity and specificity of an immune dot blot test (IDBT), which relies on a '251-labeled genus-specific monoclonal antibody to detect the Chlamydia lipopolysaccharide (LPS) antigen, were improved by pretreatment of specimens with proteinase K. This enzyme destroys protein A and therefore eliminates false-positive reactions caused by the presence of Staphylococcus aureus. Proteinase K treatment also improved the ability of the assay to detect the Chlamydia LPS antigen. When the improved IDBT was compared with culture for detection of C. trachomatis in 1,394 urogenital specimens obtained from a genitourinary medicine clinic, the overall sensitivity was 96%, and LPS antigen was detected in 76 of 83 (92%) specimens that yielded less than 10 inclusions in culture. The specificity and positive and negative predictive values of the test were 97, 81.5, and 99%, respectively. Of 123 conjunctival swabs, 7 were positive by both tests and 4 swabs were positive only by IDBT. This improved IDBT provides a simple, reliable alternative to culture for the detection of C. trachomatis in urogenital and conjunctival specimens.