The effects of low-frequency ultrasound on Staphylococcus epidermidis.

Low frequency ultrasound (LFUS) significantly enhances skin permeability to a variety of drugs; however, its bacterial effects have not been well studied. Staphylococcus epidermidis organisms were grown and standardized to 10(5) cfu/ml 24 h prior to investigation and suspended in normal saline. LFUS was applied with two probes immersed in the bacterial suspensions over a range of suspension volumes, intensities, and exposure times. The suspension temperature was measured, and a sample was removed, streaked onto blood agar plates, and incubated at 37 degrees C for 24 h. Quantitative bacterial counts were then obtained. LFUS resulted in significant reductions in bacterial counts that correlated with fluid temperature. Probe size and ultrasound intensity appeared to affect bacterial counts, but were also correlated with temperature. Bacterial growth was minimal with temperatures exceeding 45 degrees C. While LFUS can reduce bacterial counts, these conditions have the potential to cause burns in humans.

Exosporial membrane plasticity of Clostridium sporogenes and Clostridium difficile.

This investigation examines the morphological alterations of the exosporial membranes of Clostridium sporogenes ATCC 3584 and Clostridium difficile ATCC 43594 and 9689 endospores in relation to their possible function during germination in the attachment/colonization process of these pathogenic bacteria. There is no reported function for the exosporial membrane, nor exosporial appendages, of clostridial endospores. Advances in high resolution, scanning electron microscopy (SEM) permit the examination of these delicate, morphological projections on intact spores in the process of attachment. The morphological plasticity of the exosporial membrane projections during activation and germination was examined to determine whether the appearance of these exosporial projections coincided with attachment of the spores to the nutritive substrate, and whether this attachment could be altered by physical agitation, cation competition with Ba2+, chelation with EDTA, or treatment with colchicine. Following incubation, activated spores could not be removed from the agar surface by agitation in water (pH 7.2 or 9.1), nor by agitation in buffer or colchicine, indicating that some form of adherence or attachment to the agar had taken place. When agitated in the presence of Ba2+ or EDTA in phosphate buffered saline or EDTA in water, all activated spores detached from the agar and exhibited decreased exosporial projections and minimal, if any, attachment structures to the agar surface. Activated clostridial spores were found to attach to agar by delicate extensions of the exosporium that could be disrupted by EDTA or Ba2+ exposure, but were unchanged when shaken in buffer or water.

Rhodamine-auramine O versus Kinyoun-carbolfuchsin acid-fast stains for detection of Cryptosporidium oocysts.

The rhodamine-auramine O stain was compared with the Kinyoun carbolfuchsin acid-fast stain for detection of Cryptosporidium oocysts in samples from patients infected with the human immunodeficiency virus (HIV). A total of 283 fecal specimens from HIV-infected patients were examined for the presence of Cryptosporidium oocysts. Duplicate smears of the fecal concentrates, prepared by the formalin ethyl acetate procedure, were stained by the Kinyoun carbolfuchsin and fluorescent rhodamine-auramine O acid-fast methods. The Kinyoun stain detected 13 positive specimens, while the rhodamine-auramine O stain detected 14 positive specimens. The average time required to survey a stained smear was 2.5 minutes with the fluorescent method, compared with 6.0 minutes with the Kinyoun technique. The rhodamine-auramine O stain is a dependable and efficient method of examining fecal smears for the presence of Cryptosporidium oocysts in a high-risk population.

Biological calcium absorption edge imaging using monochromatic synchrotron radiation.

Soft X-ray contact absorption edge images of unfixed, unstained biological specimens were made using monochromatic synchrotron radiation. X-ray contact replicas of unfixed, hydrated biological specimens at the nitrogen absorption edge and above and below the CaLIII absorption edge were compared to comparative conventional morphological and elemental high-resolution imaging methods (scanning and transmission electron microscopy, TEM-histochemistry and TEM-X-ray microanalysis). Soft X-ray absorption edge images made above the calcium absorption edge clearly revealed morphological detail and identified regions ladened with calcium as verified by TEM histochemistry of identical spores. Similarly, nitrogen absorption edge images identified residual nitrogenous material in the spore resuspension medium, and non-viable spores with nitrogen loss due to protoplast disaggregation.

Autologous fibrin gel: bactericidal properties in contaminated hepatic injury.

Fibrin glue is an effective hemostatic agent in a variety of clinical situations; its utility is limited by potential transmission of viral infection. We studied the bactericidal properties of fibrin gel (FG) in a murine contaminated hepatic injury model and in vitro by agar plate culture method. Intra-abdominal abscess formation and adhesion rate were assessed following controlled liver injury in association with abdominal contamination with 10(7) Bacteroides fragilis and hepatorrhaphy (H, n = 15) or FG (n = 12). Animals treated by hepatorrhaphy had a significantly greater intra-abdominal abscess rate (15/15 vs. 4/12, p less than 0.05) and adhesion rate (14/15 vs. 6/12, p less than 0.05) than animals treated with FG. Fibrin gel is bactericidal to Bacteroides fragilis, Enterobacter faecium, Escherichia coli, and Staphylococcus aureus but has no effect against Klebsiella pneumoniae or Pseudomonas aeruginosa; the plasma component appears active. Fibrin gel demonstrates significant improvement in adhesion formation and intra-abdominal abscess rate when compared with suture hepatorrhaphy. Fibrin gel appears protective in contaminated hepatic injury.

Absorption edge imaging of bacterial endospores with synchrotron radiation.

This article describes a new method of viewing biological specimens by taking advantage of the absorptive characteristics of monochromatic X-rays above and below the absorption edge of a specific element. Bacterial endospores were imaged before and after treatment with an experimental vanadium-containing sporocide using monochromatic synchrotron radiation at the nitrogen absorption edge, and above and below the vanadium LIII absorption edge. This morphological study demonstrates a rapid, easy-to-use method of soft X-ray absorption edge imaging that can be used by the biologist to obtain morphological and elemental information that is not readily accessible using conventional microscopic and analytic techniques.

Hansenula anomala: a new fungal pathogen. Two case reports and a review of the literature.

Fungal infections are characteristic of severely immunocompromised patients. Noncandidal yeasts represent a growing proportion of such infections. Risk factors for developing fungal infections include the use and abuse of central venous catheters. Two patients with gynecologic malignant neoplasms became fungemic with Hansenula anomala, a yeast of the Ascomycetes class, after insertion of central venous catheters. Frequent catheter manipulation and prolonged use favored the development of fungemia in both patients. A review of the literature revealed 19 additional cases over the course of four decades, all in hosts with underlying diseases. Thirteen of these cases have been described in the last 18 months, suggesting either increased recognition or increased frequency of infection with this organism. All tested isolates have been susceptible to amphotericin B. Patients have generally responded to catheter withdrawal and amphotericin B administration. Hansenula anomala is an opportunistic pathogen, whose clinical behavior resembles that of Candida species.

Graft infection and bacteremia with Listeria monocytogenes in a patient receiving hemodialysis.

Patients receiving hemodialysis are particularly susceptible to infection. We report a case of Listeria monocytogenes bacteremia and graft infection developing in a patient receiving hemodialysis. Vancomycin hydrochloride therapy was initiated in anticipation of a staphylococcal infection, and continued as the patient's clinical course improved. Ultimately the arteriovenous graft required excision. Identification of the organism and drug susceptibilities are described. To our knowledge, this is the first case report of both an L monocytogenes arteriovenous graft infection and the use of vancomycin in the treatment of this infection.