Biomedical subjects

K C Carroll

Publications and source records attributed to K C Carroll.

At least 19 recordsLinked to original sources

PubMed2005

Comparison of an automated repetitive sequence-based PCR microbial typing system to pulsed-field gel electrophoresis for analysis of outbreaks of methicillin-resistant Staphylococcus aureus.

Rapid and sensitive methods for accurate strain delineation are essential for monitoring and preventing transmission of methicillin-resistant Staphylococcus aureus (MRSA). Pulsed-field gel electrophoresis (PFGE) has been the standard technique for strain typing most bacterial species including MRSA. The goal of this study was to compare the performance of the DiversiLab microbial typing system (Bacterial BarCodes, Inc., Houston, TX) (rep-PCR) to that of PFGE for typing MRSA isolates from five well-defined outbreaks. The DiversiLab rep-PCR assay is a rapid, semiautomated method based on PCR amplification of specific regions between noncoding repetitive sequences in the bacterial genome. rep-PCR was performed according to the manufacturer's recommendations, and the results were analyzed and dendrograms were generated using the DiversiLab analysis software (version 2.1.66 a). PFGE was performed and interpreted according to published procedures. rep-PCR results using similarity indices (SI) of 80%, 85%, and 90% were compared to PFGE analysis. In addition, intra- and interrun reproducibility was determined for rep-PCR. Overall, correct assignment to outbreak versus nonoutbreak clusters occurred for 91 of 109 isolates (85% agreement) when using a SI of 85%. For each specific outbreak, concordance between rep-PCR and PFGE ranged from 73% to 100%. There were 18 discrepant results (17%). Fourteen isolates were unique by PFGE, but they were placed in clusters by rep-PCR; the other 4 were placed in clusters different from those assigned by PFGE. Intra- and interrun reproducibility was excellent. Times to results were 12 to 24 h for rep-PCR compared to 2 to 4 days for PFGE. Rapid, standardized results and excellent reproducibility make rep-PCR a valuable tool for use in MRSA investigations. However, since rep-PCR was less discriminatory than PFGE, we recommend that it be used to screen isolates, followed by testing isolates which share the same rep-PCR pattern with a more sensitive method, such as PFGE or multilocus sequence typing.

Anti-Bacterial Agents↗

PubMed2004

Staphylococcus aureus with reduced susceptibility to vancomycin.

Infections with Staphylococcus aureus with reduced susceptibility to vancomycin continue to be reported, including 2 cases caused by S. aureus isolates with full resistance to vancomycin. This review first outlines the definitions of vancomycin-intermediate S. aureus (VISA) and vancomycin-resistant S. aureus (VRSA) and risk factors for infection. Next, we describe the mechanisms of resistance and methods of laboratory detection of the organisms. Finally, we address infection control and management issues associated with isolation of VISA and VRSA.

Animals↗

PubMed2003

Comparison of a commercial reversed passive latex agglutination assay to an enzyme immunoassay for the detection of Shiga toxin-producing Escherichia coli.

A multicenter study was performed to compare the performance of a prototypic reversed passive latex agglutination assay (VTEC Screen "Seiken"; Denka-Seiken, Japan) with the Premier EHEC Enzyme Immunoassay (Meridian Diagnostics, USA) for the detection of Shiga toxin in 554 diarrheal stool samples. Standard culture on sorbitol MacConkey agar and the use of latex agglutination reagents were included to identify the Escherichia coli O157, O26 and O111 serotypes. There was 99% agreement between the VTEC screen and enzyme immunoassay (kappa=0.823). Seventeen samples were positive for toxin by one or both assays. One toxin-positive sample using the enzyme immunoassay and four positive samples using the VTEC Screen could not be confirmed. Serotypes identified included: O157:H7 (n=8), O26 (n=2), O111 (n=1) and O45:H2 (n=1). The VTEC screen is easy to perform and comparable to the Meridian EHEC test for detection of Shiga toxin in clinical samples.

Escherichia coli↗

PubMed2002

Identification of Mycobacterium spp. by using a commercial 16S ribosomal DNA sequencing kit and additional sequencing libraries.

Current methods for identification of Mycobacterium spp. rely upon time-consuming phenotypic tests, mycolic acid analysis, and narrow-spectrum nucleic acid probes. Newer approaches include PCR and sequencing technologies. We evaluated the MicroSeq 500 16S ribosomal DNA (rDNA) bacterial sequencing kit (Applied Biosystems, Foster City, Calif.) for its ability to identify Mycobacterium isolates. The kit is based on PCR and sequencing of the first 500 bp of the bacterial rRNA gene. One hundred nineteen mycobacterial isolates (94 clinical isolates and 25 reference strains) were identified using traditional phenotypic methods and the MicroSeq system in conjunction with separate databases. The sequencing system gave 87% (104 of 119) concordant results when compared with traditional phenotypic methods. An independent laboratory using a separate database analyzed the sequences of the 15 discordant samples and confirmed the results. The use of 16S rDNA sequencing technology for identification of Mycobacterium spp. provides more rapid and more accurate characterization than do phenotypic methods. The MicroSeq 500 system simplifies the sequencing process but, in its present form, requires use of additional databases such as the Ribosomal Differentiation of Medical Microorganisms (RIDOM) to precisely identify subtypes of type strains and species not currently in the MicroSeq library.

DNA, Bacterial↗

PubMed2001

Comparison of three transport systems (Starplex StarSwab II, the new Copan Vi-Pak Amies Agar Gel collection and transport swabs, and BBL Port-A-Cul) for maintenance of anaerobic and fastidious aerobic organisms.

Of utmost importance in evaluations of clinical samples for infectious agents is proper specimen transport to the clinical laboratory. In the present study we compared three transport systems (the new Starplex StarSwab II, the new Copan Vi-Pak Amies Agar Gel collection and transport swabs, and the BBL Port-A-Cul) for survival of anaerobic and fastidious aerobic bacteria. The new Copan Vi-Pak system has been modified by nitrogen gas flushing to keep an ideal low E(h) condition and to prevent oxidation of the transport medium. The Copan Vi-Pak system outperformed the other two swabs evaluated by maintaining the viabilities of both anaerobic and fastidious aerobic bacteria for 24 h for the majority of the organisms evaluated. This time period should be sufficient for transport of specimens to the clinical microbiology laboratory without compromising organism recovery.

Bacteria, Aerobic↗

PubMed2001

Evaluation of the Prodesse Hexaplex multiplex PCR assay for direct detection of seven respiratory viruses in clinical specimens.

We evaluated the Hexaplex assay (Prodesse, Waukesha, WI) for the detection of 7 respiratory viruses (influenza A and B, parainfluenza 1-3, and respiratory syncytial virus [RSV] A and B). The Hexaplex assay was performed on 300 respiratory samples during the 1999-2000 respiratory virus season. Results of this assay were compared with shell vial cell culture and/or direct fluorescent antibody stain. The overall sensitivity and specificity of the assay were 96.6% and 94.1%, respectively. The respective sensitivity and specificity of the Hexaplex assay for detection of specific virus groups were as follows: influenza A, 98.6% and 97.8%; influenza B, 100% and 100%; and for parainfluenza viruses (1-3), 100% and 99.1%. The assay did not perform as well with patients infected with RSV: sensitivity and specificity were 91.0% and 98.6%, respectively. There are 2 major drawbacks to this assay: it is technically demanding (3-4 hours hands-on time), and it is expensive ($80-$90 direct cost). Nevertheless, because of the excellent sensitivity and specificity, the Hexaplex assay may be valuable in the diagnosis of respiratory viral infections in immunocompromised patients.

Animals↗

PubMed2000

Comparison of the TOX A/B test to a cell culture cytotoxicity assay for the detection of Clostridium difficile in stools.

The TOX A/B Test (Techlab, Blacksburg, VA, USA) was compared to cell culture cytotoxicity assay on 1109 consecutive diarrheal stool samples collected from patients with the presumptive diagnosis of Clostridium difficile disease. The TOX A/B Test is an enzyme immunoassay in a microtiter format that detects both toxins A and B. The procedure used for this study takes approximately 1.5 h to perform. Cell culture cytotoxicity was performed by using a fibroblast cell line in a microtiter format read at 4 h, 24 h, and 48 h. One hundred ninety-four of the 1109 samples were positive by the "gold standard" cytotoxicity assay, whereas 189 were positive by EIA. There was a 98.5% agreement between the two assays. When compared to the cytotoxicity assay, the EIA had an initial sensitivity of 94.3% and a specificity of 99.3%. However, after resolution of six discrepants using another ELISA for toxin A detection the sensitivity, specificity, positive and negative predictive values for the TOX A/B test are as follows: 94.5%; 100%; 100%; 98.8%. The corresponding values for the cytotoxicity assay are: 97%; 100%; 100%; and 99.3%. This test seems to have excellent sensitivity and specificity as compared to an in-house cell culture cytotoxicity assay. It is sensitive enough to use as a stand-alone test for the detection of C. difficile toxin in laboratories that do not have cell culture cytotoxicity testing capability.

Cell Culture Techniques↗

PubMed2000

Evaluation of the roche AMPLICOR enterovirus PCR assay in the diagnosis of enteroviral central nervous system infections.

BACKGROUND: Enteroviruses cause a substantial number of cases of aseptic meningitis annually in the USA. While culture has been useful in the detection of patients with viral meningitis it is time-consuming and lacks sensitivity. Detection of viral nucleic acid in patient specimens has been demonstrated to improve enteroviral detection. OBJECTIVES: A research use only commercial amplification assay, the Roche AMPLICOR EV test, was compared to culture for the diagnosis of enteroviral meningoencephalitis. STUDY DESIGN: Four-hundred and sixty-five consecutive CSF samples sent prospectively for suspicion of enteroviral infection were evaluated by PCR and shell-vial culture. Clinical information and CSF analysis were used to resolve PCR positive, culture negative samples. Sensitivity and specificity were calculated using resolved data. RESULTS: There were 138 samples which met the definition of a true positive. Of these culture detected 77 (sensitivity 55.8%) and PCR detected 136 (sensitivity 98.6%). PCR missed two culture positive samples. Upon repeat testing, these CSF samples were found to contain inhibitors. CONCLUSIONS: The Roche AMPLICOR EV-PCR test was statistically more sensitive than culture (P<0.001) in the detection of enteroviruses in CSF in patients suspected of having enteroviral meningitis. This assay also has the advantage of a rapid turnaround time of 5-6 h compared to 3-5 days for culture.

Adolescent↗

PubMed2000

Laboratory diagnosis of atypical pneumonia.

"Atypical pneumonia" is a term loosely applied to lower respiratory tract infections that are not characterized by signs and symptoms of lobar consolidation. This description can apply to disease caused by a variety of bacterial, viral and even protozoan organisms. In reality, differentiation as to etiology of pneumonia cannot be distinguished on the basis of clinical presentation. This review will discuss the epidemiology, clinical manifestations, and laboratory diagnosis of Mycoplasma pneumoniae, Chlamydia sp., Legionella sp., Bordetella pertussis, and Coxiella bumetii, the most common agents associated with atypical pneumonia. Unfortunately, because many of these pathogens are intracellular, culture systems are either not available or the techniques employed are costly, time-consuming or unsafe. Until molecular techniques are standardized and widely available, diagnosis will depend upon serologic confirmation. Given the relative importance of these organisms as causes of community acquired pneumonia, current practice guidelines recommend empiric therapy with a macrolide in patients well enough to be treated as an outpatient. However, diagnostic tests should be performed in any patient requiring hospitalization.

Bordetella Infections↗

PubMed2000

Comparison of sorbitol MacConkey agar and a two-step method which utilizes enzyme-linked immunosorbent assay toxin testing and a chromogenic agar to detect and isolate enterohemorrhagic Escherichia coli.

Enterohemorrhagic Escherichia coli (EHEC) and specifically serotype O157:H7 are a significant cause of hemorrhagic gastrointestinal disease and the hemolytic uremic syndrome. Methods currently used in clinical microbiology labs, such as sorbitol-MacConkey (SMAC) agar, reliably detect only O157:H7. We have evaluated a two-step method that has the potential to identify and isolate all EHEC serotypes, including serotype O157:H7. This method utilizes a chromogenic selective-differential medium for the isolation of E. coli together with an enzyme-linked immunosorbent assay (ELISA) that detects the Shiga-like toxins Stx1 and Stx2. Both are commercially available and usable in a wide range of clinical microbiology laboratories. Compared to a Vero cell cytotoxic assay, SMAC had sensitivities of 23.5% for the identification of all EHEC serotypes and of 50.0% for the identification of O157:H7 alone. The two-step method had sensitivities of 76.5 and 100%, respectively. The ELISA alone had a sensitivity of 82.4% in the detection of Stx1 and Stx2. The specificity was 100% in all cases. Overall, 14 EHEC isolates were obtained: 8 (58%) O157:H7, 2 (14%) O26, 2 (14%) O111:NM, 1 (7%) O103:H2, and 1 (7%) O121:H19. All but one were isolated during the months of May to September. The two-step method was found to be considerably more expensive than SMAC for both positive and negative samples.

Agar↗

PubMed2000

Detection of Legionella species in respiratory specimens using PCR with sequencing confirmation.

Legionella spp. are a common cause of community-acquired respiratory tract infections and an occasional cause of nosocomial pneumonia. A PCR method for the detection of legionellae in respiratory samples was evaluated and was compared to culture. The procedure can be performed in 6 to 8 h with a commercially available DNA extraction kit (Qiagen, Valencia, Calif.) and by PCR with gel detection. PCR is performed with primers previously determined to amplify a 386-bp product within the 16S rRNA gene of Legionella pneumophila. We can specifically detect the clinically significant Legionella species including L. pneumophila, L. micdadei, L. longbeachae, L. bozemanii, L. feeleii, and L. dumoffii. The assay detects 10 fg (approximately two organisms) of legionella DNA in each PCR. Of 212 clinical specimens examined by culture, 100% of the culture-positive samples (31 of 31) were positive by this assay. By gel detection of amplification products, 12 of 181 culture-negative samples were positive for Legionella species by PCR, resulting in 93% specificity. Four of the 12 samples with discrepant results (culture negative, PCR positive) were confirmed to be positive for Legionella species by sequencing of the amplicons. The legionella-specific PCR assay that is described demonstrates high sensitivity and high specificity for routine detection of legionellae in respiratory samples.

Base Sequence↗

PubMed2000

Rapid detection of Campylobacter jejuni in stool specimens by an enzyme immunoassay and surveillance for Campylobacter upsaliensis in the greater Salt Lake City area.

The Alexon-Trend, Inc. (Ramsey, Minn.), ProSpecT Campylobacter microplate assay was compared with culture on a Campy-CVA plate (Remel, Lenexa, Kans.) and blood-free campylobacter agar with cefoperazone (20 microg/ml), amphotericin B (10 microg/ml), and teicoplanin (4 microg/ml) (CAT medium; Oxoid Limited, Hampshire, England) with 631 patient stool samples. The CAT medium was used to isolate Campylobacter upsaliensis. The enzyme immunoassay (EIA) had a sensitivity and a specificity of 89 and 99%, respectively, and the positive and negative predictive values were 80 and 99%, respectively. Even though we extensively looked for C. upsaliensis in stool samples from patients from the greater Salt Lake City area, we did not isolate this species during the study period. The overall excellent specificity of the EIA allows rapid detection and treatment of positive patients; however, a negative result should be confirmed by culture when clinical suspicion is high.

Campylobacter↗

PubMed1999

Isolation of a new subspecies, Bartonella vinsonii subsp. arupensis, from a cattle rancher: identity with isolates found in conjunction with Borrelia burgdorferi and Babesia microti among naturally infected mice.

Bacteremia with fever due to a novel subspecies of Bartonella vinsonii was found in a cattle rancher. The subspecies shared major characteristics of the genus Bartonella in terms of most biochemical features and cellular fatty acid profile, but it was distinguishable from other subspecies of B. vinsonii by good growth on heart infusion agar supplemented with X factor and by its pattern of enzymatic hydrolysis of peptide substrates. DNA relatedness studies verified that the isolate belonged to the genus Bartonella and that it was genotypically related to B. vinsonii. The highest level of relatedness was observed with recently characterized strains from naturally infected mice that were coinfected with Borrelia burgdorferi and Babesia microti. We propose the name Bartonella vinsonii subsp. arupensis subsp. nov. as the new subspecies to accommodate these human and murine isolates.

Animals↗

PubMed1999

A polymerase chain reaction-based epidemiologic investigation of the incidence of nonpolio enteroviral infections in febrile and afebrile infants 90 days and younger.

OBJECTIVE: Enteroviruses are important pathogens in infants, but their true contribution to febrile illness in infants </=90 days old is unknown. The purpose of this study was to use the polymerase chain reaction (PCR) for diagnosis of enteroviral (EV) infection in febrile and afebrile infants </=90 days of age to improve the understanding of the epidemiology of EV infection in this population. METHODS: Patients included all unimmunized, febrile infants </=90 days of age admitted to Primary Children's Medical Center (Salt Lake City, UT) for sepsis evaluation from December 1996 to December 1997. Blood, urine, cerebrospinal fluid, and throat swabs were tested for enteroviruses using a PCR assay (Roche Molecular Systems, Branchburg, NJ). Alternate PCR assays separated polio and nonpolio enteroviruses. Results of bacterial cultures, outcome, and hospital charges were obtained. Blood from afebrile, control infants </=90 days old was tested for enteroviruses. RESULTS: A total of 345 febrile infants were enrolled; 89 (25.8%) were positive for enterovirus. The incidence of EV infection ranged from 3.2% in January to 50% in August and October. Five EV-positive, febrile infants (5.6%) had concomitant urinary tract infections, and 1 (1. 1%) had concomitant bacteremia. Infants with confirmed EV infection were significantly less likely to have bacterial infection than those who were EV-negative. All infants infected with an enterovirus recovered. Average length of stay was 3 days, average charges were nearly $4500. Eighty-six afebrile, control infants were enrolled; 6 (6.9%) were positive for enterovirus; 3 had received oral polio vaccine. CONCLUSIONS: Nonpolio EV infections commonly cause fever in infants </=90 days of age. Rates of EV positivity are low in afebrile, unimmunized infants. The use of PCR to identify febrile infants with nonpolio EV infections may decrease length of hospital stay, unnecessary antibiotic administration, and charges.

Bacterial Infections↗

PubMed1999

Pain assessment and management in critically ill postoperative and trauma patients: a multisite study.

BACKGROUND: Pain in critically ill patients is undertreated. OBJECTIVES: To examine patients' perceptions of pain and acute pain management practices in a large metropolitan area to provide direction for improvements in pain relief. METHODS: In a descriptive, correlational study, data were collected from 213 patients in 13 hospitals. Interviews with patients, chart reviews, and interviews with nurse leaders were used to examine institutional and individual approaches to pain management. RESULTS: Twenty-eight percent of patients did not recall an explanation of a pain management plan, and 64% were often in moderate to severe pain while in the intensive care unit. High pain intensity correlated with wait for an analgesic (P < .001), expectations of less pain (P < .001), and longer stay in the intensive care unit (P < .001). Low satisfaction correlated with expectations of less pain (P < .001), often being in moderate to severe pain (P < .001), and long wait for an analgesic (P < .001). In the first 24 hours postoperatively, only 54% of patients had a numerical pain rating documented; 91% had a pain description. The amount of opioid given on postoperative day 1 was influenced by pain intensity (P < .001), the patient's age (P = .03), type of surgery (P = .002), and route of analgesic (P < .001). Only 33% of patients had nonpharmacological pain interventions documented. CONCLUSIONS: Despite moderate to severe pain, patients are generally satisfied with their pain relief. Measuring patients' satisfaction alone is not a reliable outcome for determining the effectiveness of pain management. Realistic expectations of patients about their pain may enhance coping, increase satisfaction, and decrease pain intensity after surgery.

Aged↗

PubMed1998

Comparison of various in vitro susceptibility methods for testing Stenotrophomonas maltophilia.

A total of 57 clinical isolates were screened by disk diffusion for a related pharmacodynamic study. Testing was performed using National Committee for Clinical Laboratory Standards guidelines, except that results were interpreted at 16 to 18 h and 48 h. Of the 57 isolates, 19 were randomly chosen for additional comparative susceptibility testing of five methods (disk diffusion, Etest, Alamar colorimetric broth microdilution, Vitek, and MicroScan) and an in-house broth microdilution method. The two diffusion methods (disk and Etest) had the closest correlation. The commercial broth microdilution methods and the in-house microdilution method generated inconsistent results for all agents except trimethoprim-sulfamethoxazole. Vitek compared poorly with both diffusion and microbroth dilution methods. The most significant discrepancies were evident with all methods when the incubation period was extended to 48 h. When results were interpreted at 48 h, the incidence of resistance for all bactericidal agents was approximately double the resistance observed at 16 to 18 h. The bacteriostatic agents, trimethoprim-sulfamethoxazole and doxycycline, demonstrated the greatest in vitro activity and were least influenced by extended incubation with diffusion methods. Because correlative in vivo and in vitro studies have not revealed an effective therapeutic regimen for serious S. maltophilia infections, susceptibility results with all testing methods should be interpreted with caution when choosing therapy for patients with life-threatening infections. Susceptibility testing for this heterogeneous group remains controversial and routine testing, with the possible exception of doxycycline (or minocycline) and trimethoprim-sulfamethoxazole, should be avoided. Our data support that if testing is done with bactericidal agents, consideration should be given to interpretation after 48-h incubation.

Anti-Bacterial Agents↗

PubMed1998

Role of the microbiology laboratory in the diagnosis of lower respiratory tract infections.

The appropriate use of the clinical microbiology laboratory for diagnosing lower respiratory tract infections is controversial. As in clinical care, it is crucial to categorize the presenting illness properly as acute bronchitis, an acute exacerbation of chronic bronchitis, community-acquired pneumonia, or nosocomial pneumonia if diagnostic efforts to establish a microbial etiology are to be productive for the individual patient and affordable to society. The greatest potential benefit of microbiological investigations lies in the etiologic diagnosis of pneumonia. For community-acquired pneumonia, evaluation of a gram-stained smear of sputum in terms of both quality and microorganisms present can help guide initial therapy as well as aid interpretation of subsequent culture results. As discussed in this review, the role of the clinical microbiology laboratory in the etiologic diagnosis of nosocomial and complicated pneumonias is more extensive and, in addition to evaluation of respiratory secretions, may include cultures of blood, pleural fluid, and specimens obtained by bronchoscopy. However, a prerequisite for the use of all currently available tests is their deployment for patients with clinical and radiographic evidence of pneumonia.

Acute Disease↗

PubMed1998

Enhancement of the AMPLICOR enterovirus PCR test with a coprecipitant.

The incorporation of a commercially available coprecipitant into the AMPLICOR enterovirus PCR test specimen preparation enhanced the sensitivity and reproducibility of this assay. Fifty-five previously tested archived cerebrospinal fluids (CSF) specimens were tested in a blind study in duplicate with and without Pellet Paint coprecipitant (Novagen, Inc., Madison, Wis.). Of these specimens, 26 had previously been determined to be positive and 29 had previously been determined to be negative. All previously positive CSF specimens were positive when Pellet Paint was used and only 18 were positive without Pellet Paint. No previously negative specimens were positive on repeat testing with or without Pellet Paint. The background signal was not affected by the addition of Pellet Paint. These data support the utility of a coprecipitant in minimizing false-negative results.

Cerebrospinal Fluid↗