Eileen M. Burd

Human Papillomavirus and Cervical Cancer

SUMMARY Of the many types of human papillomavirus (HPV), more than 30 infect the genital tract. The association between certain oncogenic (high-risk) strains of HPV and cervical cancer is well established. Although HPV is essential to the transformation of cervical epithelial cells, it is not sufficient, and a variety of cofactors and molecular events influence whether cervical cancer will develop. Early detection and treatment of precancerous lesions can prevent progression to cervical cancer. Identification of precancerous lesions has been primarily by cytologic screening of cervical cells. Cellular abnormalities, however, may be missed or may not be sufficiently distinct, and a portion of patients with borderline or mildly dyskaryotic cytomorphology will have higher-grade disease identified by subsequent colposcopy and biopsy. Sensitive and specific molecular techniques that detect HPV DNA and distinguish high-risk HPV types from low-risk HPV types have been introduced as an adjunct to cytology. Earlier detection of high-risk HPV types may improve triage, treatment, and follow-up in infected patients. Currently, the clearest role for HPV DNA testing is to improve diagnostic accuracy and limit unnecessary colposcopy in patients with borderline or mildly abnormal cytologic test results.

Validation of Laboratory-Developed Molecular Assays for Infectious Diseases

SUMMARY Molecular technology has changed the way that clinical laboratories diagnose and manage many infectious diseases. Excellent sensitivity, specificity, and speed have made molecular assays an attractive alternative to culture or enzyme immunoassay methods. Many molecular assays are commercially available and FDA approved. Others, especially those that test for less common analytes, are often laboratory developed. Laboratories also often modify FDA-approved assays to include different extraction systems or additional specimen types. The Clinical Laboratory Improvement Amendments (CLIA) federal regulatory standards require clinical laboratories to establish and document their own performance specifications for laboratory-developed tests to ensure accurate and precise results prior to implementation of the test. The performance characteristics that must be established include accuracy, precision, reportable range, reference interval, analytical sensitivity, and analytical specificity. Clinical laboratories are challenged to understand the requirements and determine the types of experiments and analyses necessary to meet the requirements. A variety of protocols and guidelines are available in various texts and documents. Many of the guidelines are general and more appropriate for assays in chemistry sections of the laboratory but are applied in principle to molecular assays. This review presents information that laboratories may consider in their efforts to meet regulatory requirements.

The Effects of Magnesium, Calcium, EDTA, and pH on the In Vitro Adhesion of Staphylococcus epidermidis to Plastic

The effects of increasing concentrations of magnesium (Mg2+), calcium (Ca2+) or EDTA, and pH on the adhesion of five slime‐positive strains of Staphylococcus epidermidis (Se+) to plastic were examined using an in vitro microwell assay. The addition of Mg2+ (as either MgSO4 or MgCl2) to the bacterial suspension in concentrations as low as 16 μM significantly enhanced the adhesion of all test strains to plastic (P<0.001). Similarly, the addition of Ca2+ (as CaCl2) in concentrations exceeding 128 μM produced a significant increase in the adhesion of all test strains, but not to the extent observed with Mg2+. In contrast, the adhesion of all test strains to plastic was significantly reduced in the presence of EDTA at concentrations greater than 8 mM. However, EDTA in concentrations as low as 0.25 mM caused a significant decrease in the adhesion of two strains of Se+. The effect of pH was variable, but at a pH of 5.0 and 6.0, the adhesion of all test strains was significantly reduced compared to control values at a pH of 7.0. Two strains showed a significant increase in adhesion at a pH of 8.0. We also compared the effects of these variables on the adherence of a slime‐negative phase variant derived from a slime‐positive parent strain. With the exception of pH, the adhesion of both strains in response to increasing divalent cations or EDTA was similar. These data indicate that, in addition to hydrophobic interactions, ligand‐specific binding, and slime production, pH and divalent cations, especially Mg2+, are important determinants of the adhesion of S. epidermidis to plastic surfaces in vitro. This has possible implications in the pathogenesis of biomedical implant infections caused by these organisms.

Late Prosthetic Hip Joint Infection with Actinomyces israelii in an Intravenous Drug User: Case Report and Literature Review

ABSTRACT Late infections with Actinomyces israelii have been described for prosthetic hip joints but not in association with intravenous drug use. We present a case of a 43-year-old intravenous drug user who developed A. israelii infection in connection with a hip prosthesis 11 years after implantation, and we review four previously reported cases of Actinomyces prosthetic joint infections.

Pustular Dermatitis Caused by Dermatophilus congolensis

ABSTRACT We describe a case of pustular dermatitis in a 15-year-old girl who had just returned from horseback riding camp. Based on gram staining, colony characteristics, biochemical reactions, and whole-cell fatty acid analysis, the causative agent was identified as Dermatophilus congolensis. The literature contains few reports of human infection with this organism.

Human herpesvirus 6 (HHV-6)-associated dysfunction of blood monocytes

HHV-6 is a recently described member of the herpesvirus family. HHV-6-associated marrow failure and interstitial pneumonitis where macrophages are the primary infected cell type have been described in marrow transplant patients (Carrigan, 1991; Drobyski et al., 1993). In recent studies we have shown that exposure of normal human marrow to HHV-6GS (a type A strain) or several type B strains resulted in suppression of growth factor induced outgrowth of macrophages by > 90% (Burd and Carrigan, 1993). Additional experiments using HHV-6GS to characterize the effects of the virus on peripheral blood monocytes showed that the respiratory burst capacity of these cells as determined by luminol-enhanced chemiluminescence using phorbol myristate acetate as a trigger was decreased by 83% +/- 13% in a series of 5 experiments. The decreased respiratory burst was evident as early as 15 min after exposure to virus. Experiments in which cells were separated on a fluorescence activated cell sorter prior to respiratory burst assay showed that the response was mediated solely by peripheral blood monocytes. The respiratory burst response of virus-exposed cells to opsonized zymosan was not affected, indicating that the virus may selectively interfere with the protein kinase C pathway of cellular activation. Ultracentrifugation of stock material to remove infectious virus showed that the suppressive factor was associated with the supernatant fraction. These findings suggest that HHV-6 infection may be associated with a defect in one of the major monocyte activation pathways, and this could be of importance with respect to persistent infection by HHV-6 in immune compromised patients.

Effect of preoperative fusidic acid on the normal eyelid and conjunctival bacterial flora

A randomised trial comparing the topical application of 1% fusidic acid with 0.3% gentamicin solution in the reduction of the normal preoperative lid and conjunctival microbial flora was performed. Forty patients awaiting cataract surgery were randomly divided into two groups consisting of 20 patients each. The first group received a 1% microcrystalline suspension of fusidic acid, the second 0.3% gentamicin to the preoperative eye every two hours between 0600 and 2400 daily for 48 hours preoperatively. Cultures were obtained from both the lid margins and the conjunctival sac of both groups prior to antibiotic therapy and again in the operating theatre before surgery. Microbiological identification and colony counts were performed by standard laboratory methods. Staphylococcus epidermidis was the commonest micro-organism isolated. Statistical analysis revealed no significant differences in the ability of a 1% microcrystalline suspension of fusidic acid and 0.3% gentamicin in eliminating or reducing the normal preoperative conjunctival or lid flora.

Microbial Content of Kohl

ABSTRACT Three brands of commercially prepared kohl imported from India were tested and were found to vary widely in microbial content. Heavy contamination, primarily with Bacillus species, Gram-ne...

Effects of Human Intravenous Immune Globulin on Diarrhea Caused by Shiga-Like Toxin I and Shiga-Like Toxin II in Infant Rabbits

Shiga toxin and the related Shiga‐like toxins (SLT), produced by Escherichia coli, can cause hemorrhagic colitis and hemolytic uremic syndrome (HUS). Human intravenous immune globulin (HIVIg) blocks the cytotoxicity of some SLTs in vitro. To examine the ability of HIVIg to modify disease caused by Shiga‐like toxin I or Shiga‐like toxin II (SLT‐I or SLT‐II), we injected 3‐day‐old rabbits intraperitoneally with SLT‐containing cell‐free supernatants from Escherichia coli O157: H7. A subset of rabbits was treated with subcutaneous HIVIg. All rabbits given 104 CD50 of SLT‐1 developed severe diarrhea, and 5 died. When HIVIg 500 mg/kg was given in addition to SLT‐I, only 6 of 18 rabbits (33.3%) developed diarrhea (P < 0.0001), and 1 died. HIVIg 500 mg/kg or 1,000 mg/kg protected against diarrhea when given one hour prior to toxin. HIVIg 1,000 mg/kg was protective when administered one hour after toxin, but not at 6 or 24 hr. Seventeen of 18 rabbits given 106 CD50 of SLT‐II developed severe diarrhea, and 4 died. In contrast to SLT‐I‐associated disease, HIVIg had no effect on diarrhea in rabbits given SLT‐II. We conclude that HIVIg protects infant rabbits from diarrhea and death caused by by intrapertoneally administered SLT‐I, but does not affect the course of SLT‐II‐associated illness.

Corneal and intraocular penetration of topical and subconjunctival fusidic acid.

Corneal tissue absorption and intraocular penetration of fusidic acid were assessed in the rabbit after topical or subconjunctival application. Corneal tissue levels of fusidic acid one hour after the last topical application of the drug were well above the minimum inhibitory concentrations (MICs) for most Gram-positive and many Gram-negative organisms. Adequate levels were achieved in the aqueous at one hour following the last topical application, but no significant levels were detected in the vitreous. The corneal tissue and aqueous levels declined at 12 and 24 hours following the last drug application, however, corneal tissue levels at 24 hours were considered to be above the MICs for most Gram-positive organisms. A single subconjunctival injection of 100 mg of fusidic acid produced levels above the MICs of most organisms in the cornea, aqueous, and vitreous which persisted over 24 hours, but subconjunctival injection of fusidic acid at this concentration resulted in conjunctival necrosis and corneal decompensation. Fusidic acid penetrates well into avascular tissue and fully penetrates corneas with both intact and debrided epithelium, as evidenced by the intracameral drug levels. Good corneal penetration and absence of known topical toxicity make fusidic acid suitable for the treatment of microbial keratitis caused by susceptible organisms.