Biomedical subjects

J H Carr

Publications and source records attributed to J H Carr.

12 recordsLinked to original sources

PubMed1996

Comparison of chemical dehydration and critical point drying for the stabilization and visualization of aging biofilm present on interior surfaces of PVC distribution pipe.

In this study, fixation of attached glycocalyx on the interior surfaces of polyvinyl chloride distribution pipe remnants was compared with and without ruthenium red/osmium tetroxide and, in the final preparatory phase, with chemical dehydration and critical point drying. SEM examination of interior surface of the polyvinyl chloride pipe showed varying concentrations of adherent bacteria, depending on the preparatory technique used. It was concluded that using a combination of ruthenium red/osmium tetroxide and critical point drying is the optimum method for visually demonstrating aging biofilm on the interior surface of contaminated polyvinyl chloride pipe.

Bacterial Adhesion↗

PubMed1993

The colonization of solid PVC surfaces and the acquisition of resistance to germicides by water micro-organisms.

Six common water bacteria were examined for their ability to colonize polyvinyl chloride (PVC) surfaces, survive various germicidal treatment, and re-establish themselves in sterile distilled water (SDW). For each test, two 30.4 cm PVC pipes attached to a 90 degrees PVC elbow were filled with 600 ml of distilled water inoculated with either Pseudomonas aeruginosa, Ps. cepacia, Ps. mesophilica, Acinetobacter anitratus, Mycobacterium chelonae or M. chelonae var. abscessus. After 8 weeks contaminated water was removed and the pipes were exposed to 600 ml of 1:213 iodophor disinfectant (ID), 1:128 phenolic detergent (P), 1:256 quaternary ammonium compound (QA), stock iodophor antiseptic (IA), 2% formaldehyde (F), 10-15 ppm free chlorine (C), 2% glutaraldehyde (G) and 70% ethanol (E). These germicides were periodically sampled, neutralized and examined for surviving organisms. After exposure for 7 d the germicides were removed and each pipe was refilled with SDW. This was assayed at 7 d intervals to determine microbial re-establishment. Samples were removed during microbial conditioning and examined by scanning electron microscopy (SEM). Pseudomonads were isolated directly from ID, QA, C, P and F, and mycobacteria from QA, IA, ID, P, G, C and F. Pseudomonas aeruginosa and Ps. cepacia survived in PVC pipes after 7 d of exposure to P, ID and C; Ps. mesophilica, after C and ID; and both mycobacteria, after C. SEM examination of PVC remnants revealed bacterial attachment and formation of extracellular material with embedded cells. These studies show that common water bacteria can attach and colonize the interior surface of PVC pipes and develop significant resistance to the action of certain germicides.(ABSTRACT TRUNCATED AT 250 WORDS)

Acinetobacter↗

PubMed1992

Characterization of a novel Rochalimaea species, R. henselae sp. nov., isolated from blood of a febrile, human immunodeficiency virus-positive patient.

Isolation of a Rochalimaea-like organism from a febrile patient infected with human immunodeficiency virus was confirmed. Analysis of 16S rRNA gene sequences, together with polymerase chain reaction and restriction endonuclease length polymorphism analysis of a portion of the citrate synthase gene, demonstrated that the agent is closely related to members of the genus Rochalimaea and that the isolate is genotypically identical to the presumptive etiologic agent of bacillary angiomatosis. However, the same genotypic analyses readily differentiated the new isolate from isolates of other recognized Rochalimaea species as well as other genera of bacteria previously suggested as putative etiologic agents of bacillary angiomatosis and related syndromes. We propose that the novel species be referred to as Rochalimaea henselae sp. now.

Adult↗

PubMed1991

Investigations of intrinsic Pseudomonas cepacia contamination in commercially manufactured povidone-iodine.

OBJECTIVE: Laboratory investigations were initiated with a povidone-iodine antiseptic solution that was intrinsically contaminated with Pseudomonas cepacia. These investigations were helpful in understanding the microbicidal and chemical properties of iodophor solutions and the mechanism by which P cepacia can survive in iodine-containing antiseptics. DESIGN: Included in these studies were: prolonged survival of P cepacia; available and free iodine determinations; microbial challenge studies; and scanning electron microscopic examination of contaminated antiseptic. RESULTS: P cepacia survived in this iodophor antiseptic up to 68 weeks from the date of manufacture. A uniform concentration of 1% available iodine was found in all lots of povidone-iodine tested as specified on the product label, but free iodine (I2) values varied greatly. Low free iodine levels of 0.23 to 0.46 ppm were associated with the contaminated lot of povidone-iodine. Solutions of povidone-iodine with varying levels of free iodine were rapidly microbicidal when challenged with cells of P cepacia derived from culture broth and washed or adapted to growth in water. P cepacia cells taken directly from contaminated povidone-iodine survived for significantly longer periods of time. Large numbers of P cepacia were found embedded in extracellular material and among strands of glycocalyx between cells as shown by scanning electron microscopy. CONCLUSIONS: The physical thickness of cellular and extracellular material that forms on surfaces could protect embedded organisms from the microbicidal action of disinfectants and antiseptics and subsequently allow for extended microbial survival times. Manufacturers should be aware that distribution piping surfaces colonized with bacteria may be a source of product contamination and resistant organisms.

Colony Count, Microbial↗

PubMed1990

Influence of the 60-megadalton plasmid on adherence of Escherichia coli O157:H7 and genetic derivatives.

The adherence of enterohemorrhagic Escherichia coli serotype O157:H7 and various genetic derivatives to Henle 407 intestinal and HEp-2 epithelial cell lines was examined by light and electron microscopy. The parent outbreak strain, 7785, harbors a 60-megadalton serotype-specific plasmid designated pO157 and adhered to both cell lines, as determined by light microscopy. A plasmidless derivative, 2-45, showed reduced adherence to both cell lines. After being labeled with Tn801, pO157 was transformed into E. coli C600, E. coli HB101, and E. coli GH42, and back into 2-45. Both E. coli C600 and HB101 transformants adhered weakly; full adherence was restored to the 2-45(pO157::Tn801) transformant. Transmission electron microscopy (EM) demonstrated the intimate attachment of HB101(pO157::Tn801) to Henle 407 cells which formed cuplike structures and areas of possible actin polymerization adjacent to adhering bacterial cells; scanning EM further extended these observations. EM studies of E. coli O157:H7 strains were hampered by extensive intestinal cell damage, presumably due to the action of Shiga-like toxins. EM also demonstrated that 7785 and its plasmidless derivative 2-45 were piliated and that no pili were apparent on HB101(pO157::Tn801) or GH42//(pO157::Tn801). The plasmid pO157 appears to modify the eucaryotic cell adherence of E. coli O157:H7 and to confer that adherence on E. coli HB101 through surface structures other than pili. These findings, when compared with other published reports, also suggest similarities between enterohemorrhagic and enteropathogenic E. coli adherence properties.

Bacterial Adhesion↗

PubMed1987

Acanthamoeba keratitis in soft contact lens wearers. A case-control study.

Acanthamoeba keratitis is a rare, serious protozoal infection of the cornea associated with wearing contact lenses. To identify risk factors in soft contact lens wearers, we interviewed 27 patients with Acanthamoeba keratitis and 81 uninfected matched controls to compare contact lens care practices, brands of contact lenses and associated solutions, and behavioral activities. Patients were significantly more likely than controls to use homemade saline instead of commercially prepared saline (21/27 [78%] vs 14/81 [17%]; odds ratio [OR], infinity), and wear their lenses while swimming (17/27 [63%] vs 24/81 [30%]; OR, 6.2). Contact lens disinfection schedules could be determined for 25 of the patients and all of the controls. Patients were significantly more likely than controls to disinfect their lenses less frequently than recommended by lens manufacturers (18/25 [72%] vs 26/81 [32%]; OR, 5.8). Microbiologic assay of contact lens solutions from controls showed frequent contamination with high levels of bacteria. Acanthamoeba species were isolated from homemade saline solutions from two controls. These findings emphasize adherence to recommended methods of soft contact lens care, especially when using nonsterile lens care solutions.

Amebiasis↗

PubMed1985

Investigation of a new motor assessment scale for stroke patients.

The purpose of this paper is to present and describe a motor assessment scale (MAS) for stroke patients and to report on the investigation of two aspects of its reliability. The MAS is a brief and easily administered assessment of eight areas of motor function and one item related to muscle tone. Each item is scored on a scale from 0 to 6. To check interrater reliability, we videotaped five stroke patients while they were being assessed with the MAS. These scores were used as the criterion ratings. Twenty raters then assessed these patients, and their results were correlated with the criterion ratings. We determined test-retest reliability by assessing on two occasions, separated by a four-week interval, 14 stroke patients whose recovery was considered to be stable and by correlating these scores. The MAS was found to be highly reliable with an average interrater correlation of .95 and an average test-retest correlation of .98.

Adult↗

PubMed1981