Characterizing viral subtypes to assess patterns of HIV transmission.

We characterized HIV-1 subtypes among 204 persons newly diagnosed with HIV in Ontario from 2003 to 2005 using samples from the Canadian HIV Strain and Drug Resistance Surveillance Program. We examined HIV-1 subtype by demographic characteristics and exposure category, and determined independent predictors of infection with a non-B HIV subtype using multivariate logistic regression. The distribution of HIV subtypes was: B 77.0%, C 10.3%, AG 4.9%, A 2.5%, AE 2.5% and others 3.0%. Overall, 23.0% were non-B, greater in women than in men (62.8% versus 12.4%, P < 0.0001) and persons under 35 years (31.1% versus 18.5% in those ≥35, P = 0.04). Non-B subtype was predominant (78.9%) among persons from HIV-endemic regions and considerable (28.6%) among other persons infected heterosexually. In multivariate modelling adjusted for gender, non-B subtype was significantly associated with birth in an HIV-endemic region (adjusted odds ratio [aOR] 59.2, P < 0.0001) and heterosexual exposure (aOR 6.3, P = 0.02). Additionally, compared with men who had sex with men, non-B subtype was greater among heterosexual women (aOR 17.8, P < 0.001) and women who injected drugs (injection drug use, aOR 13.4, P = 0.01). We found a non-negligible proportion of non-B subtypes among women infected heterosexually not from HIV-endemic countries, providing interesting insights into HIV transmission patterns.

Identification of performance problems in a commercial human immunodeficiency virus type 1 enzyme immunoassay by multiuser external quality control monitoring and real-time data analysis.

In June 2005, a pilot program was implemented in Canadian laboratories to monitor the performance of the Abbott human immunodeficiency virus types 1 and 2 (HIV-1/2) gO enzyme immunoassay (EIA). Two different external quality control (QC) reagents and a "real-time" software analysis program were evaluated. In November 2005, higher-than-expected calibrator rate values in these kits were first reported at the Ontario Ministry of Health (Etobicoke), followed by the Alberta Provincial Public Health Laboratory (Edmonton and Calgary) and others. These aberrations were easily and readily tracked in "real time" using the external QC reagents and the software program. These high calibrator values were confirmed in Delkenheim, Germany, by Abbott, and a manufacturing change was initiated beginning with lot 38299LU00, which was distributed to laboratories in Canada in April 2006. However, widespread reports of calibrator failure by laboratories outside Canada were made in March 2006. In April 2006, Abbott Diagnostics initiated a level III investigation to identify the root cause, which was prolonged storage, under uncontrolled storage conditions, of the raw material used in the manufacture of the matrix cells. To the best of our knowledge, this is the first example of a program in Canada for serological testing that combines a common external QC reagent and a "real-time" software program to allow laboratories to monitor kit performance. In this case, external QC monitoring helped identify and confirm performance problems in the Abbott HIV-1/2 gO EIA kit, further highlighting the benefit of implementing such a program in a national or multilaboratory setting for laboratories performing diagnostic and clinical monitoring testing.

Susceptibility of anaerobic bacteria to nine antimicrobial agents and demonstration of decreased susceptibility of Clostridium perfringens to penicillin.

The activity of moxalactam, cefoxitin, cephalothin, cefamandole, chloramphenicol, clindamycin, metronidazole, and ticarcillin was determined against 344 isolates of anaerobic bacteria. The activity of penicillin G was determined as well for 234 isolates not of the Bacteroides fragilis group. Moxalactam was more active than cephalothin and cefamandole and slightly less active than cefoxitin. Metronidazole was the most active antimicrobial agent against the B. fragilis group, whereas chloramphenicol was most active overall. Clostridium species were the most resistant group of organisms tested. Relatively high concentrations of penicillin were required to inhibit the C. perfringens strains: 80% at 0.5 U/ml and 100% at 16 U/ml. Our study demonstrates the need for periodic anaerobe susceptibility testing in order to better guide empiric antibiotic therapy.

Aerobic and anaerobic urethral flora of healthy females in various physiological age groups and of females with urinary tract infections.

We characterized the aerobic and anaerobic urethral flora of healthy females in three physiological age groups (premenarcheal, reproductive, and postmenopausal) and of females with urinary tract infections. The mean number of species per sample was 6.5, 7.7, and 10.3 for each of the physiological age groups, respectively, and 6.5 for the urinary tract infection group. Marked quantitative changes were seen with age and disease. Aerobes accounted for 65.6 and 73.8% of the flora of the premenarcheal and reproductive age groups, respectively, whereas anaerobes were dominant in the postmenopausal age group, accounting for 65.5% of the flora. Aerobic gram-negative rods were not isolated from any of the premenarcheal or reproductive-age subjects. Of the 10 postmenopausal subjects, 5 carried aerobic gram-negative rods, but these organisms accounted for only 1% of the flora. In contrast, they constituted 95% of the urethral flora of the urinary tract infection group. Bacteroides melaninogeneicus was commonly isolated and was the dominant isolate in the postmenopausal age group. Bacteroides fragilis was recovered from 7 of the 10 postmenopausal subjects, but these organisms constituted only 3% of the total flora. The factors responsible for the changes in urethral flora with age remain to be determined.

Bacteriocin typing of Clostridium perfringens in human feces.

Three hundred and ninety-nine isolates of Clostridium perfringens from enriched stool specimens of 51 individuals (about eight colonies per person) were typed by bacteriocins. Forty-nine percent of these persons carried more than one bacteriocin type in their stool, and some had three or four different stains as determined by bacteriocin typing. Weekly stool specimens obtained from seven positive volunteers over a period of 5 weeks were screened for C. perfringens, and several colonies from each person were typed. This survey demonstrated that the number of types fluctuated with time, several types could be carried simultaneously, and the isolation of the organism was variable. Nine new bacteriocin types of C. perfringens were isolated in this study.