Olof Ringertz

The origin of Staphylococcus saprophyticus from cattle and pigs.

Staphylococcus saprophyticus is a common cause of urinary tract infections. We have earlier shown that the bacterium is a contaminant of food of animal origin. In order to trace the natural reservoir of the bacterium, samples were taken from farming environment and from slaughtered carcasses. S. saprophyticus was found in 7.1% of rectal swabs from cattle carcasses and in 7.3% of rectal swabs from slaughtered pigs. The seasonal variation of these isolates paralleled the seasonality of urinary tract infections due to the same bacterium. S. saprophyticus was also isolated in 1.1% of rectal swabs from living cows, in 1.6% from pasture grass and from 12.4% of various indoor fodder. The fodder presented a seasonal distribution with a peak incidence of S. saprophyticus some months earlier than in rectal swabs. The bacterium was especially frequent in samples of fodder taken from the managers. S. saprophyticus is most likely a bacterium with a zoonotic origin.

Corynebacterium Group JK in a Hematological Ward: Infections, Colonization and Environmental Contamination

Because 2 patients with acute leukemia expired in septicemia with multiresistant Corynebacterium group JK (JK) the occurrence and significance of these bacteria in a hematological ward was analysed. During the following year JK was isolated in 6 other patients with acute leukemia, in 5 as a colonizing agent and in 1 as cause of an anorectal abscess. The environmental investigation with cultures from all patients, personnel and rooms in the ward disclosed heavy contamination with JK in 2 isolation rooms housing JK-colonized patients. Contamination with JK in other rooms was very sparse and there were no JK-positive cultures from personnel or other patients in the ward. Repeated environmental cultures taken after the JK-colonized patients left the isolation rooms showed sparse contamination with JK. Thus, JK strains can survive in the environment for a long time.

Detection of Chlamydia trachomatis in urine from men with urethritis.

The performance of a commercial EIA (Chlamydiazyme) for detection ofChlamydia trachomatis in urine specimens was compared with that of culture of urethral samples from men with urethritis. The incidence of chlamydial infection on the basis of culture results was 34 % (56/167). The sensitivity, specificity, positive and negative predictive values for the EIA were 55 % (31/56), 98 % (109/111), 94 % (31/33) and 81 % (109/134), respectively, compared with culture. Although this EIA has a high specificity, the low sensitivity makes it valueless as a clinical tool for demonstrating chlamydial antigen in urine from men with urethritis.

Plasmid-identified staphylococcus saprophyticus isolated from the rectum of patients with urinary tract infections

Among 15 strains of Staphylococcus saprophyticus of various origin, 13 presented different plasmid patterns, making plasmid identification a useful epidemiological marker. In a consecutive study of 14 young female patients with urinary tract infection caused by S. saprophyticus, 6 patients were simultaneously positive for the same bacterium in the stools. Three paired samples contained the identical plasmid-identified clone of S. saprophyticus indicating that the rectum may be a reservoir of this urinary pathogen.

Evaluation of a commercial enzyme immunoassay versus culture for the detection ofChlamydia trachomatis

A commercial EIA (Chlamydiazyme) for detection ofChlamydia trachomatis was evaluated in comparison to culture using genital specimens from 472 men and 279 women. The sensitivity of the EIA compared with culture was 66.0% in men and 71.4% in women, while the specificity was 99.7% and 95.9% respectively. The EIA failed more often to detect chlamydial antigen when the number of inclusion bodies found in the corresponding cultures was ⩽ 100/well. A direct test (MicroTrak) was performed on the EIA samples which showed discordant results compared to corresponding cultures. One of 17 EIA positive samples, and 12 of 36 EIA negative samples were positive in the direct test (p<0.05). A cut-off absorbance value of 0.1 is recommended by the manufacturer in the EIA. However, 84.2% of the EIA negative samples in the negative absorbance interval 0.05–0.099 corresponded with a positive culture. In view of variations in the sensitivity of the culture technique between laboratories and the low sensitivity of the EIA found in this study, it is recommended that each laboratory using the EIA compare it to culture. It is also recommended that an equivocal zone around the cut-off value be used in the EIA, the zone to be established by each laboratory using the test.

Levels of erythromycin in tear fluid and serum in infants with conjunctivitis

38 newborns with purulent conjunctivitis were treated with oral erythromycin ethylsuccinate 25 mg/kg every 12 h for 14 days. 3-4 days after initiation of therapy, erythromycin levels in serum and tear fluid were measured 1 and 12 h after the administration of erythromycin. The level of erythromycin in tear fluid was significantly higher than that in serum 1 and 12 h after administration of the antibiotic. On both occasions the concentrations of erythromycin in tear fluid and in serum exceeded the minimum inhibitory concentration (MIC) in vitro for Chlamydia trachomatis.