Assessing viral retention and elimination in rotary dental instruments

The authors of this article used a laboratory model of herpes simplex virus infection to assess the potential for contamination of dental handpieces by a human viral pathogen. They found that although all the handpieces in the study were fitted with anti-retraction valves, it was not until the units were flushed internally and disinfected externally that the pathogens were eliminated.

Rotary dental instruments and the potential risk of transmission of infection: herpes simplex virus

A laboratory model of herpes simplex virus infection was used to assess the potential contamination of dental handpieces. When contaminated instruments were treated with surface disinfection and internal chemical disinfection, viable virus was eliminated in all instruments.

Need for treatment of gonorrhea to be effective against Chlamydia trachomatis

Men and women with gonorrhea or contact to gonorrhea are frequently co-infected with Chlamydia trachomatis. To assess the importance of using treatment regimens active against both Neisseria gonorrhoeae and C trachomatis, tetracycline 500 mg orally four times daily for five days, with activity against both organisms, was compared with ceftriaxone, 250 mg once intramuscularly, with activity against only N gonorrhoeae. N gonorrhoeae microbiological failure occurred in six of 148 patients (4%) on tetracycline and zero of 85 on ceftriaxone. Microbiological failure for C trachomatis occurred in zero of 27 on tetracycline and 10 of 12 (83%) on ceftriaxone (P<0.001). In addition, 14 others on ceftriaxone had C trachomatis first isolated after treatment. When all types of microbiologialc and clinical failures are included, outcome was significantly better on tetracycline (P<0.001). Optimal treatment of patients with gonorrhea must include regimens with activity against both C trachomatis and N gonorrhoeae.

Enzyme-linked immunosorbent assay for the diagnosis of trichomoniasis in women

An enzyme-linked immunosorbent assay-(ELISA) using whole Trichomonas vaginalis as antigen was developed for measurement of serum antibody to T. vaginalis. Sera from six women who denied ever having had genital contact were used as the negative control. Of 38 women with proved T. vaginalis infection, 25 (66%) had elevated ELISA values. Values were usually very stable over weeks to months of follow-up. Among a matched comparison group of 38 women attending the same clinic who did not have T. vaginalis infection (as detected by wet mounts), an elevated value was present in only eight (21%) of 38 (P less than 0.001). Thus, in this group of women, the sensitivity was 66%, the specificity, 79%, the predictive value of a positive test, 76%, and the predictive value of a negative test, 70%. Our ELISA clearly demonstrates more reactivity in women with T. vaginalis. Its usefulness as a marker of current infection is probably limited, but it could be of considerable value for seroepidemiologic studies.

Cell culture compared with broth for detection of Trichomonas vaginalis

Trichomonas vaginalis can be grown in cell culture. We studied the growth kinetics of T. vaginalis in McCoy cell culture compared with that in a conventional broth medium (Diamond TYI-S-33 medium supplemented with 10% heat-inactivated bovine serum [TYI]). In the presence of McCoy cells and two parts cell culture medium to one part TYI, a peak concentration of 2 X 10(6) to 6 X 10(6) T. vaginalis per ml was consistently achieved with inocula as low as three T. vaginalis cells per ml. Without cells, this medium did not support growth of T. vaginalis. T. vaginalis in TYI in 1-ml vials with or without McCoy cells demonstrated poor growth. In tubes containing 10 ml of TYI, inocula grew to 2 X 10(6) to 6 X 10(6) T. vaginalis per ml, but at least 3 X 10(3) T. vaginalis per tube was required to initiate growth. Thus, in vitro, cell culture was more sensitive than TYI broth in detecting low numbers of T. vaginalis. In a subsequent clinical comparison of broth and cell culture for isolation of T. vaginalis from 188 vaginal specimens and 21 urethral specimens from men, the results were in agreement for 206 specimens (98.6%). There were no situations in which culture was negative and a saline preparation showed motile trichomonads. For women, using a positive culture as the indicator of true positivity, the sensitivity of detection of T. vaginalis was 83% with the Pappenheim stain and 77% with saline preparations. These studies show that cell culture can be used for isolation of T. vaginalis from clinical specimens; it gave results comparable to those of broth culture for the group of mainly symptomatic women. Further studies should be performed to determine its utility in clinical populations such as asymptomatic women and men with and without symptoms, in which T. vaginalis is more likely to be present in low numbers.

Failure of norfloxacin to eradicate Chlamydia trachomatis in nongonococcal urethritis

Norfloxacin has some activity in vitro against Chlamydia trachomatis and Ureaplasma urealyticum, although not at levels attainable in serum. In this study, norfloxacin was administered (400 mg orally twice daily for 10 days) to men with acute nongonococcal urethritis. Of 25 men from whom C. trachomatis was initially isolated, 21 had the organism reisolated at the first follow-up visit posttreatment, and there were minimal changes in the number of inclusion-forming units in culture. Ultimately, all but 1 of the 22 men from whom C. trachomatis was initially isolated and who were monitored became clinical failures within 42 +/- 7 days posttreatment. The clinical outcome was significantly better for men from whom U. urealyticum was initially isolated but from whom C. trachomatis was not isolated. Of 27 men, 17 became and stayed culture negative for U. urealyticum at follow-ups, and clinically, 15 no longer had nongonococcal urethritis. Of these 15, all 12 monitored until at least 42 +/- 7 days posttreatment remained improved. Of 26 men from whom neither C. trachomatis nor U. urealyticum was initially isolated, 18 improved and all 15 who were monitored until at least 42 +/- 7 days posttreatment remained improved. Thus, although norfloxacin attains high levels in urine and has good tissue penetration, it had essentially no activity against chlamydial urethritis in men. It had better, but incomplete, activity against U. urealyticum. For quinolones to show promise in vivo against C. trachomatis, either the MICs will need to be much lower or the levels attained in serum will have to be much higher.