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Biomedical subjects

I Rutherford

Publications and source records attributed to I Rutherford.

At least 19 recordsLinked to original sources
PubMed1999

Artificial ventilation in the prone position.

Turning a ventilated patient into the prone position can greatly enhance arterial blood oxygenation independent of ventilator parameters. This article explores the physiology relating to pulmonary ventilation, highlighting an overall improvement in ventilation/perfusion matching as a result of the prone position. A series of small studies seems to suggest that prone positioning can have a dramatic effect on life-threatening hypoxia, including adult respiratory distress syndrome (ARDS) but as yet there have been no large, randomised, multi-centre trials to put beyond doubt the benefits of prone ventilation. Turning the patient prone precipitates many issues in caring for him/her in this position. Many are practical problems and the article goes on to explore a variety of these, including turning and positioning the patient, emergencies and access and the psychological effects of being in the prone position. It is important that nurses understand the physiological basis for any actions, including turning the patient prone, but it is also important that nurses doctors and other professionals appreciate the practical difficulties that this form of management can produce. All team members must work together to ensure a safe, cohesive approach to turning and caring for the ventilated patient in the prone position.

Adult↗
PubMed1996

Sternotomy infection with Mycoplasma hominis: a cause of "culture negative" wound infection.

Wound infections with Mycoplasma species are unusual; diagnosis may be delayed because of the growth characteristics of this organism. We report Mycoplasma hominis infection of sternotomy wounds in two patients. The first presented with fever and drainage from the incision 1 week after coronary artery bypass grafting. The other patient presented with drainage from the incision three weeks after double-lung transplantation. In both cases, initial cultures were negative, but the typical colonial morphology of M. hominis was subsequently detected. Successful treatment consisted of debridement and long courses of antibiotic therapy; omental flap grafting was eventually required for the second patient. Other published cases were reviewed and compared with the newly reported cases.

Aged↗
PubMed1993

Comparison of vidas Clostridium difficile toxin-A assay and premier C. difficile toxin-A assay to cytotoxin-B tissue culture assay for the detection of toxins of C. difficile.

Damage to the intestinal mucosa by Clostridium difficile (CD) is toxin mediated. Two enzyme immunoassays (EIAs) for toxin-A detection, the automated Vitek immunodiagnostic assay system CDA (Vidas CDA), and the Premier toxin A (Premier) were tested for their ability to detect toxin A in 301 stool samples and compared with an in-house tissue culture assay for toxin B (TCA). Of these 301 samples, 49 were TCA positive and 252 were TCA negative. Agreement between Vidas CDA and TCA on the initial run was 85% (255 of 301) and increased to 94% (278 of 296) when discordant samples were retested from available frozen specimens. Corresponding levels of agreement for Premier were 91% (272 of 301) and 98% (284 of 288), respectively. If tissue culture positivity at any titer was used as the sole criterion for positivity of the specimen, agreement with positive TCA before and after repeat testing was 57% (26 of 49) and 74% (34 of 46) for Vidas CDA and 65% (32 of 49) and 95% (36 of 38) for Premier. Agreement with negative TCA titers was good: 90% for Vidas CDA and 95% for Premier, and 98% for Vidas CDA and 99% for Premier after repeat testing. Predictive values positive and negative after repeat testing were, respectively, 88% and 96% for Vidas CDA, and 95% and 99% for Premier. Results for the automated and manual EIA methods for detection of C. difficile toxin A were obtained in 2.5 h as compared with 36-48 h for tissue culture.

Bacterial Proteins↗
PubMed1993

Aberrant Histoplasma capsulatum. Confirmation of identity by a chemiluminescence-labeled DNA probe.

A cottony, light tan, filamentous fungus with pear-shaped microconidia and lacking tuberculated macroconidia was isolated from a bronchial lavage specimen. Subculture on several media at 37 degrees C failed to convert the fungus to a yeast form after several weeks; attempts at in vivo conversion in mice were also unsuccessful. Sera obtained several months apart showed M bands with Histoplasma capsulatum (HC) antigen by immunodiffusion and an increase in complement fixation titers with mycelial and yeast phase antigens of HC. Parallel identity was obtained on two occasions with exoantigen culture confirmation reagents for HC from Immuno-Mycologics as well as one of identity with Nolan reagents. Extracts from four Chrysosporium spp. strains had no identity reactions with HC with either kit. The fungus was identified as HC by the Accuprobe Histoplasma chemiluminescence-labeled DNA probe directed at ribosomal RNA, whereas all four Chrysosporium spp. isolates tested negative. DNA probes are a fast and accurate method to confirm the identity of aberrant fungal isolates.

Aged↗
PubMed1991

Comparison of the Vitek Immunodiagnostic Assay System with an indirect immunoassay (Toxostat Test Kit) for detection of immunoglobulin G antibodies to Toxoplasma gondii in clinical specimens.

The value and convenience of testing for specific anti-Toxoplasma gondii antibodies have led to the development of various antibody detection methods, such as the enzyme immunoassay. Two enzyme immunoassays, the Vitek Immuno-Diagnostic Assay System (VIDAS; Vitek Systems, Hazelwood, Mo.) and the Toxostat Test Kit (TST; Whittaker Bioproducts, Walkersville, Md.), were compared for their ability to detect T. gondii immunoglobulin G antibodies in fresh human sera. Specimens were tested according to the instructions of each manufacturer. Of 304 serum specimens tested, the results for 282 (93%) agreed in both assays (77 were positive and 205 were negative). The results for the remaining 22 (7%) specimens were discrepant; 20 of the 22 specimens tested low positive or equivocal by Toxostat and negative by VIDAS. Upon retesting, 8 of these 22 specimens were in concordance, increasing the level of agreement to 95.3%. Intra-assay reproducibility was tested with four to nine replicates of each of seven samples (four positive, one negative, and two equivocal) by both tests and six replicates of one standard by VIDAS. Coefficients of variation (CVs) for VIDAS were 6, 8, 10, 15, 18, 19, and 23% for the samples and 14% for the standard. For Toxostat the CVs were 2, 8, 10, 10, 13, and 16%. In general, CVs for VIDAS were slightly larger than the CVs for Toxostat. Day-to-day variability over 3 days was tested by VIDAS for only six samples (three positive, two negative, and one equivocal) and four standards; CVs ranged from 2 to 15% for the samples and from 6 to 13% for the standards. In conclusions, VIDAS is a rapid, convenient, non-labor-intensive, and easily performed test for the detection of immunoglobulin G antibodies to T. gondii in serum specimens.

Animals↗
PubMed1991

Corneal microsporidiosis in a patient with AIDS.

Microsporidia are obligate intracellular protozoan parasites that are becoming increasingly recognized as opportunistic pathogens in patients with AIDS. They have been associated with enteritis, hepatitis, and peritonitis and recently keratoconjunctivitis. Gram stain demonstrates the presence of these organisms on light microscopic sections. The specific diagnostic features that distinguish microsporidia from other small nonspore-forming organisms are best demonstrated by electron microscopy, which is also used to characterize the members of Microsporea. In this study, salient histopathologic features of microsporidia in corneal epithelium obtained from an HIV-seropositive individual who developed AIDS are illustrated and discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Rapid identification of Staphylococcus epidermidis.

A panel of Minitek sugar disks, consisting of trehalose, mannitol, xylose, and sucrose, was evaluated for its ability to identify blood culture isolates of Staphylococcus epidermidis (SE). Using a heavy suspension of organism in Mueller-Hinton broth, 50 microL was pipetted onto each disk in wells of a flat-bottomed microtiter tray. The tray was covered, incubated in a moist chamber in non-CO2 at 35 degrees C, and examined after 5 and 24 hours. A color change of yellow or orange was positive; no color change (red) was negative. Expected reactions for SE were as follows: negative trehalose, mannitol, and xylose; positive, sucrose. On evaluation of 227 coagulase-negative staphylococci (CNS) at 5 and 24 hours, the panel had a sensitivity of 94 and 96%, specificity of 92 and 89%, predictive value of positive tests of 97 and 96%, and predictive value of negative tests of 84 and 87%. This panel offered an inexpensive and convenient method for differentiating SE from the other CNS in five hours.

Alkaline Phosphatase↗
PubMed1986

Susceptibility of Acanthamoeba to cryotherapeutic method.

Acanthamoeba keratitis is becoming an increasingly well-known clinical entity. The Acanthamoeba species in their encysted state are resistant to antimicrobial agents, resulting in corneal infections that are refractory to medical therapy. Corneal cryotherapy has been used to treat Acanthamoeba keratitis with varying and equivocal success. We subjected trophozoites and cysts of two species of Acanthamoeba recovered from corneal infections to trials of in vitro freeze-thaw-refreeze cryotherapeutic methods. The trophozoites of both species were killed in all trials. However, the cysts of both species survived all trials. Cryotherapy may not be an effective means to eliminate Acanthamoeba cysts from the cornea.

Amebiasis↗
PubMed1986

Detection of methicillin-resistant Staphylococcus epidermidis.

To determine whether methods suggested for detecting methicillin-resistant Staphylococcus aureus apply equally to methicillin-resistant Staphylococcus epidermidis, 135 S. epidermidis isolates were tested by the Vitek AMS gram-positive susceptibility card (Vitek Systems, Inc., Hazelwood, Mo.) and by modifications of agar screen, disk diffusion, and microdilution methods. Modifications included 24- versus 48-h incubation, unsupplemented versus 2% NaCl-supplemented broth, and standard versus direct inoculum. At 24 h, the highest number of resistant strains, 59, was detected by oxacillin (1 microgram) disk diffusion. At 48 h, three additional strains were judged resistant. With one exception, results for oxacillin disk diffusion and agar screen were equivalent at 24 and 48 h. Vitek detected 50 resistant strains. Significantly fewer resistant strains were detected at 24 h by methicillin disk diffusion (5 micrograms) and methicillin microdilution with 2% NaCl. For oxacillin microdilution, neither 2% NaCl supplementation nor the method of inoculum preparation significantly affected the results. Oxacillin microdilution with cation- rather than non-cation-supplemented broth detected significantly fewer (n = 33) resistant strains at 24 h; 51 were resistant at 48 h. To detect methicillin-resistant S. epidermidis, a direct inoculum with either 24-h oxacillin disk diffusion and reincubation of intermediate strains for an additional 24 h or 24-h oxacillin agar screen and reincubation of strains with no growth for a total of 48 h is recommended.

Humans↗
PubMed1986

Susceptibility of Acanthamoeba to soft contact lens disinfection systems.

Members of the genus Acanthamoeba are increasingly recognized as agents of indolent, chronic, infectious keratitis. Recently, Acanthamoeba corneal infection has been reported in some persons who wear soft contact lenses. In this study, three "heat" and three "cold" soft contact lens disinfection systems were tested according to the manufacturers' instructions against Acanthamoeba castellanii and Acanthamoeba polyphaga in separate trials, and with appropriate controls. Suspensions of Acanthamoeba cysts or trophozoites of each species were tested individually. Each of the three heat disinfection units killed all acanthamoebae in one cycle in all trials. A chlorhexidine 0.005%/thimerosal 0.001% solution killed A. castellanii trophozoites and cysts, but those of A. polyphaga survived. Trophozoites and cysts of both species survived an alkyl triethanol ammonium chloride 0.013%/thimerosal 0.002% solution and a hydrogen peroxide 3% preparation. Heat disinfection overall appears to be more effective in killing Acanthamoeba trophozoites and cysts as compared to cold disinfection methods.

Amoeba↗
PubMed1981

Effect of concentration and time upon inactivation of tobramycin, gentamicin, netilmicin and amikacin by azlocillin, carbenicillin, mecillinam, mezlocillin and piperacillin.

Carbenicillin and ticarcillin have been shown to inactivate aminoglycoside antibiotics. This study evaluated the effect of time upon in vitro interaction between mixtures of four aminoglycoside antibiotics at two concentrations with azlocillin, mecillinam, mezlocillin, piperacillin and carbenicillin at three concentrations. By linear regression analysis, the inactivation of each aminoglycoside antibiotic was shown to be directly proportional to the concentration of the semisynthetic penicillin. Aminoglycoside inactivation was greater after 72 hr of incubation with the penicillins than after 24 hr of incubation. Inactivation by each semisynthetic penicillin was greater for tobramycin and gentamicin than for netilmicin and amikacin, especially at higher concentrations of the penicillins. At concentrations of 500 microgram/ml, significantly less inactivation of amikacin occurred when compared to netilmicin. There was little difference in inactivation of a specific aminoglycoside by any of the semisynthetic penicillin antibiotics. No significant change in aminoglycoside activity occurred when the aminoglycosides were stored with the semisynthetic penicillin derivatives at -70 degrees C for 30 days. Conclusions from this study are: 1) serum specimens containing aminoglycoside-penicillin combinations should be tested immediately or frozen before antibiotic assay and 2) aminoglycoside inactivation by the newer semisynthetic penicillins may be important in patients with renal failure who are receiving these antimicrobial agents.

Amdinocillin↗
PubMed1981

Clinical features of Strongyloides stercoralis infection in an endemic area of the United States.

Infection with Strongyloides stercoralis, the most common intestinal parasite at our hospital, was encountered in 56 patients over a 3-yr period. The majority of the patients were male adults over 50 years old who had a chronic debilitating associated illness; about half the patients were immunocompromised. Strongyloidiasis was usually a chronic relapsing illness of mild to moderate severity characterized by gastrointestinal complaints (diarrhea, pain, tenderness, nausea, vomiting) and peripheral eosinophilia. Hypoalbuminemia also occurred. Stool examination for larvae was an effective method of diagnosing the parasite, and treatment with thiabendazole was usually successful. The frequent occurrence of S. stercoralis in geriatric patients with other medical problems and the delays in making the diagnosis suggest that the clinical spectrum of strongyloidiasis is greater than generally appreciated by the medical profession. Increased awareness of S. stercoralis is important to prevent the hyperinfection syndrome, which was estimated to occur in 1.5-2.5% of our patients.

Adolescent↗
PubMed1978

Empyema with Trichomonas species.

A 35-year-old alcoholic male patient developed an empyema secondary to presumed aspiration pneumonia. Trichomonads were demonstrated on wet mounts and Wright-Giemsa-stained, air-dried smears of pleural fluid. Treatment with metronidazole, other antimicrobial drugs, and drainage was successful in curing the empyema.

Adult↗
PubMed1977

Comparative study of three methods of identification of Enterobacteriaceae.

Three separate hospital clinical microbiology laboratories using three different identification systems participated in the identification of Enterobactericeae from a central pool of 'unknown" clinical isolates. With conventional tubed media, API-20E (Anlytab Products Inc.) and R/B tube (Corning Diagnostics) systems, there was a 91.1% agreement in the species designation. No significant differences at the 95% confidence level were found among the systems. Evaluation of individual tests within the systems used revealed lysine decarboxylase of the conventional and citrate of the API-20E system to be significantly different from the same test within the other two systems. The lysine decarboxylase of the conventional system had species relatedness, whereas the differences in citrate of the API-20E system were not related to a particular species. These individual test variations did not affect final organism identification. Reproducibility, evaluated as the system's ability to designate the same identification on two separate occasions, was 92 to 94% for each system. Exact duplication of selected sets of reactions was 60% for conventional, 45% for API-20E, and 61% for R/B. The variations in sets of reactions differed with the system and with the organism involved. The findings suggest equivalency among the three systems in ability to identify common clinical isolates of Enterobacteriaceae and point out the limited usefulness of these systems for biochemical biotyping.

Bacteriological Techniques↗