Advances in colloidal manipulation and transport via hydrodynamic interactions.

In this review article, we highlight many recent advances in the field of micromanipulation of colloidal particles using hydrodynamic interactions (HIs), namely solvent mediated long-range interactions. At the micrsocale, the hydrodynamic laws are time reversible and the flow becomes laminar, features that allow precise manipulation and control of colloidal matter. We focus on different strategies where externally operated microstructures generate local flow fields that induce the advection and motion of the surrounding components. In addition, we review cases where the induced flow gives rise to hydrodynamic bound states that may synchronize during the process, a phenomenon essential in different systems such as those that exhibit self-assembly and swarming.

Steering trajectories in magnetically actuated colloidal propellers.

Microscale colloidal doublets composed of DNA-linked paramagnetic particles and floating close to a surface are able to propel in viscous fluids when subjected to external precessing magnetic fields. We show here that for certain values of the precession angle, the composite particles can be steered into tilted rather than linear trajectories characterized by a non-vanishing lateral velocity during motion. We extend the original model developed in Phys. Rev. Lett. 101, 218304 (2008) in order to explain this phenomenon, by including high-order corrections in the expansion of the director field and demonstrate the validity of this approach by comparing the analytical results with the experimental data.

The bacteriology of chronic rhinosinusitis: results using a novel culture device.

The bacteriology of chronic rhinosinusitis is an area of great interest among rhinologists. Numerous studies have reported culture results implicating a variety of aerobic and anaerobic organisms in the etiology of this disease process. Sampling is generally accomplished through the nasal cavity, creating the potential for contamination with resident nasal flora. In some reports, strict anaerobic techniques have not been used, possibly accounting for the failure to recover these fastidious organisms. In an attempt to clarify the microbiology of chronic rhinosinusitis, we used a novel culture and transport system in 50 patients undergoing endoscopic sinus surgery. The Accu-CulShure (MLA Systems, Pleasantville, NY, USA) is a self-contained polyethylene culture swab and transport device, capable of collecting a representative sample from the sinus without contamination, and preserving the quality of the material during transport. Our aerobic and anaerobic culture results, as well as pertinent patient data, are presented. The Accu-CulShure device may permit standardization of culture techniques for future studies, and allow for more accurate determination of the microbiology of chronic rhinosinusitis.

Human parvovirus B19 in bone marrows from adults with acquired immunodeficiency syndrome: a comparative study using in situ hybridization and immunohistochemistry.

Human parvovirus B19, which infects and lyses erythroid precursors, can cause severe anemia in patients with immunodeficiency. The incidence of parvovirus infection in adult acquired immunodeficiency syndrome (AIDS) patients is unknown. Eighty-one archival formalin-fixed, paraffin-embedded (FFPE) bone marrow biopsies from 73 AIDS adults were immunostained with monoclonal R92F6 against B19 VP1 and VP2 capsid proteins using streptavidin peroxidase and streptavidin alkaline phosphatase techniques. In addition, the same tissues were hybridized in situ with a digoxigenin-labeled parvovirus B19 DNA probe. Five FFPE bone marrows, from 3 HIV-negative patients with positive immunoglobulin M (IgM) serology for parvovirus B19, and 1 parvovirus B19-infected fetal liver were positive controls. By immunoperoxidase, all tissues were negative with R92F6 except the fetal liver, which exhibited strong positivity predominantly in viral inclusions. With immunoalkaline phosphatase, all positive controls were immunoreactive with R92F6; however, the AIDS marrows were negative. With in situ hybridization (ISH), all positive controls and 7 of 81 (8.6%) of AIDS marrows were positive for B19 parvovirus DNA. We conclude that ISH is more sensitive than R92F6 immunohistochemistry in parvovirus B19 detection. A small but significant number of bone marrows from AIDS adults shows evidence of human parvovirus B19 infection.

Comparison of efficacy and cost-effectiveness of BIOMIC VIDEO and Vitek antimicrobial susceptibility test systems for use in the clinical microbiology laboratory.

Antimicrobial susceptibility testing expense may be a significant portion of a clinical microbiology laboratory's budget. This study compares the BIOMIC VIDEO system (Giles Scientific, Inc., New York, N.Y.) with the Vitek system (bioMérieux Vitek, Inc., Hazelwood, Mo.), an established automated method of antimicrobial susceptibility testing with the ability to generate MIC data. The BIOMIC system is relatively inexpensive and automates the reading of the classical disk agar diffusion test to provide both qualitative (susceptibility interpretation) and quantitative (MIC) data. The overall MIC correlation between the two systems for the 2,913 drug-organism combinations tested was 92.6%. The overall agreement for susceptibility interpretation was 97.4%. The BIOMIC system offers a 57.4% savings per test over the Vitek system. The BIOMIC system utilizes an older technology which is more efficient and yet yields results comparable to those of established automated MIC methods. The savings achievable in laboratories and hospitals nationwide may contribute significantly to the containment of national health care expenditures.

Detection of Bartonella (Rochalimaea) henselae bacteremia using BacT/Alert blood culture system.

Bartonella henselae was isolated from the blood of five febrile immunosuppressed patients using BacT/Alert (Organon Teknika, Durham, NC) automated microbial detection system. An immunofluorescence assay (using 1:1000 dilutions) was used to confirm identification of fastidious, pleomorphic, non-Gram staining, argyrophilic bacilli displaying rachety motility that had been presumptively identified as Bartonella spp. The practicality of identification of Bartonella henselae using goat antisera for use in a routine clinical microbiology laboratory was demonstrated by this study.

Evaluation of new rapid commercial enzyme immunoassay for detection of Cryptosporidium oocysts in untreated stool specimens.

Sixty-six stool specimens were evaluated by the ProSpecTR Cryptosporidium rapid enzyme immunoassay (EIA) (Alexon, Sunnyvale, Calif.). Approximately 2 g of untreated stool suspended in buffer was filtered through membranes labelled with anti-Cryptosporidium-specific antigen antibody. Anti-Cryptosporidium-specific antigen antibody was labelled with biotin, horseradish peroxidase conjugated to streptavidin, and tetramethylbenzidine, and each labelled antibody was added in sequence to the membranes. Each membrane had a positive control and test area. EIA results were compared with those of the modified acid-fast procedure. Twenty-three specimens were positive by the initial acid-fast procedure and the EIA. Forty-two specimens were negative by the initial acid-fast test and the EIA. One specimen was negative by the initial acid-fast test and positive by the EIA (sensitivity, 100%; specificity, 98.5%). This technique is easy to use by comparison with the cumbersome, labor-intensive, and more subjective microscopic methods currently available, and its sensitivity equals that of current microscopic methods.

Propensity of tampons and barrier contraceptives to amplify Staphylococcus aureusToxic shock syndrome toxin-I.

OBJECTIVE: Although the incidence of reported cases of toxic shock syndrome (TSS) has declined in recent years, the disease continues to occur in menstruating women using the newer, less-absorbent tampons or barrier contraceptives. Extant tampons and other vaginal devices were tested for the ability to induce TSS toxin-1 (TSST-1) by a TSS strain of Staphylococcus aureus MN8, a known high-toxin producer. Tested for the first time were 20 varieties of tampons, including 2 all-cotton brands newly introduced in the United States, a polyurethane contraceptive sponge, a latex diaphragm, and a polymer menstrual collection cup. METHODS: All products were washed in sterile distilled water prior to use to reduce the effect of leachable chemicals. Duplicate experiments with unwashed products were also performed. Entire tampons and other test products were immersed in brain heart infusion broth plus yeast extract (BHIY) and inoculated with S. aureus MN8, a known TSST-1 producer. After incubation, the culture supernatants were assayed for TSST-1 by gel immunodiffusion. RESULTS: Except for all-cotton tampons, greater amounts of TSST-1 were detected in the supernatant fluid of washed tampons than detected in those which were not washed. While TSST-1 levels in unwashed non-cotton tampons ranged from 0.5 to 8 microg/ml, when these products were washed, TSST-1 levels increased to 2-32 microg/ml. In all-cotton tampons, whether washed or not, there was no detectable TSST-1. CONCLUSIONS: The propensity for all-cotton tampons not to amplify TSST-1 in vitro suggests they would lower the risk for tampon-associated TSS.

Clinical, histologic, microbiologic, and biochemical characterization of the causative agent of bacillary (epithelioid) angiomatosis: a rickettsial illness with features of bartonellosis.

It has been suggested that bacillary (epithelioid) angiomatosis (BEA) is a manifestation of cat scratch disease (CSD). Because of clinical similarity between this condition and the verruga peruana phase of bartonellosis, we sought to further characterize this disease as well as its causative agent and to compare it to bartonellosis. We isolated a small flagellated pleomorphic bacillus from skin lesions of two patients with BEA. Organisms were stained successfully with Warthin-Starry silver stains, but immunohistochemistry failed to demonstrate binding with a polyclonal antibody directed against the cat scratch bacillus. Whole cell fatty-acid gas chromatography performed on both BEA organisms and Bartonella bacilliformis demonstrated marked similarity between the two. Electron microscopy of BEA organisms in tissue and in suspension revealed features characteristic of a gram negative bacillus. Based on these findings, we propose that this unusual rickettsial infectious disease with vascular proliferation may represent an unusual variant of infection with a bartonella-like organism rather than a manifestation of cat scratch disease.

Staphylococcus aureus nasal carriage in patients with rhinosinusitis.

Toxic shock syndrome has been associated with rhinologic surgery and medical devices, and it has been linked to a circulating exotoxin of a toxogenic strain of Staphylococcus aureus. One hundred forty patients with rhinosinusitis were studied. Nasal cultures were obtained. The microbiological characteristics are described. The carrier rate for Staphylococcus aureus was 35%. Thirty percent of patients selected for surgery were Staphylococcus aureus carriers. Toxin-capable isolates were identified in 40% of those tested. Users of cocaine, topical decongestants, and steroid sprays had a statistically higher rate of Staphylococcus aureus carriage compared to nonusers. It is hoped that by identifying the population at risk and defining the factors associated with the development of toxic shock syndrome, a cogent policy of prevention can be established.

Bacillary epithelioid angiomatosis occurring in an immunocompetent individual.

Within the last several years, a newly characterized condition known as bacillary epithelioid angiomatosis (BEA) has been described in a number of patients with human immunodeficiency virus (HIV) infection. All cases heretofore described have been seen in patients with the HIV infection. We recently evaluated a 37-year-old healthy man who had a localized form of BEA confirmed by biopsy, special strains, electron microscopy, and culture. We conclude that BEA as previously defined may occur in healthy, non-HIV-infected individuals.

Group G streptococcal meningitis and sepsis in a patient with AIDS. A method to biotype group G streptococcus.

Lancefield group G streptococcus is now recognized as a pathogen and has been reported to cause severe infections, including meningitis. We describe the first case of meningitis caused by this organism in a patient with acquired immunodeficiency syndrome (AIDS) and the direct transmission of the pathogen to a technologist accidentally exposed to the cerebrospinal fluid. To prove the identity of the two strains, we have tested them employing the Vitek system. We have also tested 13 other strains of group G streptococci obtained from different sources. Our results yielded 14 different biotypes with the 15 strains tested. The only identical ones were the two suspect strains from the index case and the technologist. We conclude that the biotyping system employed in our study appears to be a useful epidemiological tool for marking group G streptococci.

Microsporidial keratoconjunctivitis in acquired immunodeficiency syndrome.

We describe three patients with acquired immunodeficiency syndrome who presented with a bilateral coarse superficial epithelial keratitis due to infection with the protozoal parasite Microspora, Encephalitozoon cuniculi. Despite the extent of the corneal surface disease, conjunctival inflammation was minimal. Visual acuity ranged from 20/20 to 20/200. In one patient, the keratitis was complicated by the development of a surface defect with secondary Pseudomonas species infection. All patients had a history of exposure to household pets. Standard cultures were negative. Diagnosis was established in two of the three cases based on characteristic appearance of the protozoan in conjunctival scrapings. Electron microscopy of a conjunctival biopsy specimen in one patient confirmed the species. No recognized effective treatment is available for this infection.

Ecology of toxic shock syndrome: amplification of toxic shock syndrome toxin 1 by materials of medical interest.

Historically, the literature suggests that staphylococcal exoproteins, including enterotoxins, are stimulated by various physicochemical ecologic factors, many of which have been shown to stimulate production of toxic shock syndrome toxin 1 (TSST-1). The propensity of different fibers and other substances to amplify TSST-1 production in toxic shock syndrome-associated strains of Staphylococcus aureus, as well as a comparative analysis of the underlying mechanisms of TSST-1 production, are reported. Two hundred twenty intravaginal devices or other products and materials and 60 experimental controls were examined for their propensity to induce TSST-1 production. Certain materials are superior to unaltered cotton in providing a more absorbent fiber--nutrients are efficiently drawn in, concentrating protein between fibers, and thereby creating an ideal physicochemical environment for the amplification of TSST-1 and other toxins. The greatest stimulation of TSST-1 was observed with (in decreasing order): polyester and carboxymethyl cellulose, polyacrylates, viscose rayon, gelatin foam, polyurethane, and cotton. No toxin was found with nasal tampons (polymer of polyvinyl acetal) or with vaginal cups (an elastomeric polymer). Results are discussed in terms of specific ecologic parameters from historical as well as recent perspectives.

Automated and rapid methods in clinical microbiology: past, present and future.

Instrument development in microbiology has focused on automating the traditional process of bacterial identification using growth-dependent technology. With the advent of genetic tools, advances in immunology, and engineering innovations microbiologists are moving away from the traditions of culture-dependent technology and are concentrating on the development of rapid, specific, nongrowth-dependent systems with a potential for automation.

Toxic shock syndrome in nasal surgery: a physiochemical and microbiologic evaluation of Merocel and NuGauze nasal packing.

A prospective comparison of the microbiologic safety of Merocel versus NuGauze nasal packing in 119 surgical patients is presented. Presurgical and postsurgical nasal cultures were obtained, analyzed, and compared. The importance of a preoperative nasal culture isolate of Toxic Shock Syndrome Toxin Number 1 (TSST-1) producing Staphylococcus aureus in predicting postoperative toxigenic S. aureus isolation and Toxic Shock Syndrome symptomatology is demonstrated. An in vitro comparison of the ability of NuGauze and Merocel to amplify TSST-1 production was performed.