Comparison of MRSASelect Agar, CHROMagar Methicillin-Resistant Staphylococcus aureus (MRSA) Medium, and Xpert MRSA PCR for detection of MRSA in Nares: diagnostic accuracy for surveillance samples with various bacterial densities.

Rapid laboratory methods provide optimal support for active surveillance efforts to screen for methicillin-resistant Staphylococcus aureus (MRSA). Most laboratories struggle to determine the optimal use of resources, considering options to balance cost, speed, and diagnostic accuracy. To assess the performance of common methods, the first comparison of MRSASelect agar (MS) and CHROMagar MRSA (CA), with and without broth enrichment followed by a 24-h subculture to MS, was performed. Results were compared to those of the Xpert MRSA assay. For direct culture methods, the agreement between MS and CA was 98.8%. At 18 h, direct MS identified 93% of all positive samples from direct culture and 84% of those identified by the Xpert MRSA. For Trypticase soy broth-enriched MS culture, incubated overnight and then subcultured for an additional 24 h, the agreement with Xpert MRSA was 96%. The agreement between direct MS and Xpert MRSA was 100% when semiquantitative culture revealed a bacterial density of 2+ or greater; however, discrepancies between culture and Xpert MRSA arose for MRSA bacterial densities of 1+ or less, indicating low density as a common cause of false-negative culture results. Since 1+ or less was established as the most common MRSA carrier state, broth enrichment or PCR may be critical for the identification of all MRSA carriers who may be reservoirs for transmission. In this active-surveillance convenience sample, the use of broth enrichment followed by subculture to MS offered a low-cost but sensitive method for MRSA screening, with performance similar to that of Xpert MRSA PCR.

Solitary blood cultures: a College of American Pathologists Q-probes study of 132,778 blood culture sets in 333 small hospitals.

OBJECTIVE: To determine the frequency with which solitary blood culture samples were submitted to laboratories serving small hospitals and to ascertain whether certain hospital practices relating to the performance of blood cultures were associated with lower solitary blood culture rates (SBCRs). DESIGN: Participants in the College of American Pathologists Q-Probes laboratory quality improvement program collected data prospectively on the numbers of solitary blood culture sets from adult patients submitted to their laboratories and answered questions about their institutions' practice characteristics relating to the collection of blood culture specimens. SETTING AND PARTICIPANTS: Three hundred thirty-three public and private institutions with a median occupied bed size of 57. Participants were located in the United States (n = 329), Canada (n = 3), and Australia (n = 1). MAIN OUTCOME MEASURE: The solitary blood culture rate was defined as the number of instances in which only 1 blood culture venipuncture was performed on an individual patient during a 24-hour period divided by the total number of blood culture venipunctures that were performed during the study period. RESULTS: Participants submitted data on 132 778 adult patient blood culture sets. The SBCRs were 3.4% or less in the top-performing 10% of participating institutions (90th percentile and above), 12.7% in the midrange of participating institutions (50th percentile), and 42.5% or more in the bottom-performing 10% of participating institutions (10th percentile and below). In half the participating institutions, the SBCRs for inpatients were 8.3% or less and for outpatients, 22% or less. Solitary blood culture rates were lower for institutions in which phlebotomists rather than nonphlebotomists routinely collected blood culture specimens, in which internal policies required drawing at least 2 blood culture sets, in which hospital personnel contacted clinicians when their laboratories received requests for solitary blood culture sets, and in which quality control programs monitored SBCRs routinely. CONCLUSIONS: Hospitals can achieve SBCRs under 5%. Those hospitals with particularly high SBCRs may lower their rates by altering certain institutional practices.

Blood culture contamination: a College of American Pathologists Q-Probes study involving 640 institutions and 497134 specimens from adult patients.

OBJECTIVE: To examine clinical and laboratory practices associated with contamination of blood culture specimens from adults. DESIGN AND SETTING: A College of American Pathologists Q-Probes quality improvement study involving prospective evaluation of adult blood culture contamination rates in 640 institutions. MAIN OUTCOME MEASURE: Proportion of contaminated blood cultures. RESULTS: A total of 497134 blood cultures were studied. The median adult inpatient blood culture contamination rate was 2.5% (central 80th percentile=0.9%-5.4%) by laboratory assessment. There was no significant difference in contamination rates between inpatient and outpatient cultures (P=.273). The median contamination rate by clinical assessment (2.1%) was significantly lower (P=.005), primarily because of a lower proportion of cultures with coagulase-negative Staphylococcus that were interpreted as contaminants when only one of multiple specimens was positive. Specimen collection variables associated with significantly lower contamination rates included use of a dedicated phlebotomy service (P=.039), use of tincture of iodine for skin disinfection (P=.036), and application of an antiseptic to the top of the collection device before inoculation (P=.018). Teaching institutions and high numbers of occupied beds were demographic factors associated with higher contamination rates for inpatients but not for outpatients. Culture parameters associated with higher contamination rates included microbial growth from a single specimen, isolation of certain microbial species (eg, coagulase-negative Staphylococcus), and longer time to detect growth in culture. Contamination rates were not significantly affected by the type of blood culture method used, specimen volume, or use of a double-needle collection procedure. CONCLUSIONS: There is wide variation in blood culture contamination rates among institutions. Three specimen collection factors and three culture variables were identified as having a significant effect on blood culture contamination.

Telemicrobiology: feasibility study.

BACKGROUND: Rural hospitals generally lack staffing with infectious disease specialists or pathologists. Without on-site pathologists, the range of microbiology services offered by clinical laboratories may be limited as well. OBJECTIVE: To study the feasibility of using static-image telepathology to evaluate Gram stains of microbiologic preparations. MATERIALS AND METHODS: In this retrospective feasibility study, three pathologists evaluated Gram stains of slides from 50 cases by two viewing modalities: static-image telepathology and conventional light microscopy. Digital video images of slides were captured at two magnifications (using 40x and 100x objective lenses) at 1024 x 768 x 24-bit color and transmitted over standard telephone lines at 14,400 kbps. Pathology reports and culture results served as "truth diagnoses." Categories of interpretations were correct, minor discrepancy, or major discrepancy with regard to the implications for patient care. RESULTS: The diagnostic accuracy of video image readings and conventional light microscopy readings were nearly identical, with no statistically significant differences in the performances of specialty and nonspecialty pathologists (P > 0.05). The mean accuracies of readings of the video images and light microscopy images were 95.3% and 95.4%, respectively. Taking into account the time required by a referring pathologist to capture video digital images, telemicrobiology was somewhat less efficient than conventional light microscopy. CONCLUSIONS: Pathologists can accurately evaluate digital video images of preselected fields on Gram-stained slides. In clinical practice, however, a limiting factor may be the availability of local personnel qualified to select the microscopic fields for evaluation by telepathologists. The adequacy of the video images suggests that telepathology may also be used for remote supervision of quality assurance programs in microbiology laboratories, as well as for remote proficiency training of laboratory personnel.

Laboratory practices for reporting bacterial susceptibility tests that affect antibiotic therapy.

OBJECTIVE: To evaluate a laboratory-based process for integrating antimicrobial susceptibility, pharmacy, and clinical data with rapid physician notification to improve the care and outcome of patients with bacterial infections. DESIGN: Randomized case control study comparing standard microbiology reporting method with a targeted notification procedure. RESULTS: Of 254 cases studied, a discordance between antimicrobial susceptibility test results and antibiotic therapy was detected in 140 (55%) patients and confirmed after clinical review in 49 (19%). Appropriate changes in antibiotic therapy were made significantly sooner and in a significantly higher proportion of cases with targeted notification than with standard reporting procedures. CONCLUSIONS: Utilization of antimicrobial susceptibility results is improved by integrating clinical and therapeutic information to identify cases that require physician notification, as measured by the timeliness and appropriateness of antibiotic treatment.

Blood culture quality improvement: a College of American Pathologists Q-Probes study involving 909 institutions and 289 572 blood culture sets.

OBJECTIVE: To evaluate solitary blood culture (SBC) collections as a preanalytic quality indicator of blood culture practice. DESIGN AND SETTING: Two College of American Pathologists Q-Probes laboratory quality improvement studies involving prospective evaluation of the proportion of and reasons for SBC collections in 909 institutions. OUTCOME: Reduction in the proportion of SBCs. RESULTS: Of 289572 blood culture sets studied, the median proportion of SBCs per institution was 10.1% and 12.1% among adult inpatients, 25.4% and 33.3% among adult outpatients, and 89.0% and 100% among pediatric/infant patients in the first and second (follow-up) studies, respectively. The two most common reasons for not performing a second culture in adults were (1) test not indicated and (2) physician believed one was sufficient. When compared with inpatient cultures, a significantly higher proportion of outpatient SBCs were classified as not indicated (P < .0001). Among 198 institutions participating in both studies, a significant decline in SBC rates was observed in the subgroup (n = 50) that continued to monitor SBCs (P = .004). CONCLUSIONS: Interinstitutional evaluation of solitary blood cultures provides a benchmark for quality assessment and an opportunity for performance improvement in blood culture specimen collections.

Duplicate laboratory orders: a College of American Pathologists Q-Probes study of thyrotropin requests in 502 institutions.

OBJECTIVE: To examine the frequency and cause of duplicate thyrotropin (TSH) testing. METHODS: Five hundred two institutions, ranging in size from fewer than 100 to more than 600 beds, examined consecutively processed TSH assays to identify duplicate orders. Duplicates were defined as two or more TSH tests performed within 7 days. All together, participants submitted data on 221,476 TSH orders. RESULTS: The median institution reported that 1.5% of TSH tests duplicated a TSH order that had been received from the same patient within the previous 7 days. Ten percent of institutions reported that 4.5% or more of their TSH tests were duplicates. Institutions with higher duplicate rates tended to be larger (ie, they had a greater number of occupied beds) and to have duplicate tests that were more likely to be ordered by a physician other than the one who ordered the initial test. Participants reported that for 19% of duplicate orders, physicians were unaware that the first test had been ordered. Physicians also indicated that duplicate assays were ordered to see if a previous result had changed (15%) or to check on the accuracy of a previous result (13%). Participants reported that 11% of duplicate TSH assays that their laboratory performed had apparently never been ordered. CONCLUSIONS: A large number of institutions are performing duplicate TSH tests that, in most cases, appear to be medically unnecessary. Institutions aiming to reduce the frequency of duplicate testing should consider policies that decrease the opportunity for different physicians to order tests on a single patient and should increase the accuracy with which physician orders are transmitted to the laboratory.

Indications and immediate patient outcomes of pathology intraoperative consultations. College of American Pathologists/Centers for Disease Control and Prevention Outcomes Working Group Study.

OBJECTIVE: To evaluate the reasons (indications) for and immediate intraoperative surgical results (outcomes) associated with pathology intraoperative consultation. DESIGN: In 1992 and 1993, surgeons collaborated with pathologists in 472 voluntarily participating institutions from the United States (462), Canada (7), Australia (2), and New Zealand (1) in a study jointly sponsored by the College of American Pathologists and the Centers for Disease Control and Prevention. Pathologists selected 20 consecutive intraoperative consultations and assembled a cover letter, a checklist questionnaire, and a copy of the corresponding surgical pathology report, all of which were sent to the surgeon(s) for retrospective evaluation. PARTICIPANTS: The study was distributed to participants in the College of American Pathologists voluntary Q-Probes quality improvement and Surgical Pathology Performance Improvement programs and to Canadian and Australian hospitals with more than 200 beds. RESULTS: Evaluation of 9164 cases established the five most common indications for intraoperative consultation: (1) establish or confirm diagnosis to determine type or extent of operation (51%), (2) confirm adequacy of margins (16%), (3) confirm nature of tissue to direct sampling for immediate culture or other laboratory study (10%), (4) expedite obtaining diagnosis to inform family or patient (8%), and (5) confirm sufficient tissue submitted to secure diagnosis in permanent section (8%). The information provided by the intraoperative consultation resulted in changed surgical procedures that were either modified, terminated, or newly initiated in 47%, 30%, 6%, 9%, and 28% of cases, corresponding respectively to each of the above five common indications. Rarely cited reasons for intraoperative consultation were to expedite obtaining diagnosis for surgeon's knowledge (3%), to facilitate patient management, other professional communication or discharge planning prior to permanent section availability (3%), academic protocol (< 1%), and consultation not needed or no reason for request (< 1%). CONCLUSIONS: This multi-institutional, interdisciplinary database confirms that pathology intraoperative consultations, regardless of the initial indications, influence immediate patient care decisions, resulting in changed surgical procedures in an average of 39% of all operative cases.

Transfusion medicine monitoring practices. A study of the College of American Pathologists/Centers for Disease Control and Prevention Outcomes Working Group.

OBJECTIVE: To survey transfusion medicine practices in 1990, to determine the distribution of defects in the transfusion process, to examine the relationship between defects and complications, and to recommend improvements in the transfusion process. DESIGN: A mail survey that divided the transfusion process into 24 risk-prone steps and gathered defect rates on each step, along with incidence data for eight known complications of transfusions and other demographic information. SETTINGS: Hospitals, independent laboratories, and blood centers that provide transfusion medicine services. OTHER PARTICIPANTS: Respondents were 1365 participants in the College of American Pathologists 1991 Blood Bank Quality Assurance Survey. RESULTS: While processing 6.2 million units of blood and blood products, respondents reported detecting over 88,000 defects: 41% in the preanalytic phase of testing, 55% in the postanalytic phase, and only 4% in the analytic phase, the phase to which most monitoring efforts were devoted. A median of eight steps were actively monitored by survey participants overall, whereas 96 facilities sought defects in all 24 steps. CONCLUSIONS: Analysis of the data showed several monitoring steps provide similar information. Although monitoring of the transfusion process could not be linked with prevention of the complications studied, active surveillance does focus attention on defect-prone steps and allows testing of strategies to improve the transfusion process. We describe how defect detection systems may be improved.

Strategies for quality management in clinical microbiology.

Quality assessment and performance improvement are important management functions that add value to information and services produced by the clinical microbiology laboratory. Analytical quality control procedures are well standardized, and in many cases regulated. Whereas preanalytical and postanalytical factors have considerable impact on quality, performance assessment and improvement in this area have received less consideration. This article describes an approach to quality management of the total testing process in clinical microbiology, including interdisciplinary participation, specimen quality, test use, result use, turnaround time, information quality, user perceptions, and benchmarking.

Phlebotomists' safety practices. A College of American Pathologists Q-Probes study of 683 institutions.

We report on phlebotomists' safety practices in 683 institutions participating in the College of American Pathologists Q-Probes program. Participants inspected 38,357 phlebotomy tourniquets and 31,952 blood collection tube holders in use and found 2098 tourniquets and 2966 holders visibly contaminated with blood. In 67.8% of the institutions, at least one tourniquet or collection tube holder was contaminated. Needlestick injuries reported by phlebotomists during 1990 through 1992 were analyzed from approximately 11 million inpatient venipuncture procedures. These injuries ranged between 9.2 and 9.8 needlesticks per 100,000 venipunctures per year. Over 99% of the participants had a policy preventing recapping of needles, 45% discarded tourniquets when contaminated with blood, and 3.3% routinely assigned tourniquets to specific patients. Between 1990 and 1992, increasing frequencies of phlebotomists using gloves, replacing gloves between each inpatient phlebotomy, and handwashing after degloving were found. We cite the lack of compliance of handwashing between glove changes as suggesting need for regulatory rereview.

Inpatient phlebotomy practices. A College of American Pathologists Q-Probes quality improvement study of 2,351,643 phlebotomy requests.

We report outcomes of requests for inpatient phlebotomy procedures from 683 institutions participating in the College of American Pathologists Q-Probes programs. Of the 2,351,643 phlebotomy requests analyzed, 93.2% of venipunctures were successful, 1.6% were unsuccessful, 0.4% were partially successful, and 4.9% were not attempted by the assigned phlebotomist. Administrative inefficiencies prevented the assigned phlebotomist from attempting these venipunctures of which the most frequent reasons were patient unavailability (1.4%), patient transferred or discharged (0.9%), followed by the specimen already collected by someone else (0.7%). These results suggest that performance improvement of phlebotomy services, in general, would achieve the greatest gains by focusing attention to specific processes associated with administrative inefficiencies identified, rather than phlebotomists' technical skills.

Nosocomial infections. A college of American pathologists Q-probes study in 512 North American institutions.

We report nosocomial infection surveillance methods and hospital infection rates in 512 institutions obtained from a Q-Probes study of the College of American Pathologists, Northfield, Ill. The results showed that nosocomial infection surveillance procedures were well standardized. Use of microbiology reports was the most common case-finding method (97.3%), followed by review of the patient's medical record (86.1%). The median number of full-time equivalents per 100 occupied beds utilized for infection control services was 0.64, and these full-time equivalents spent 40% of their time on surveillance activities. A computer was used in 81% of institutions to assist in conducting surveillance, although this usage was not associated with decreased surveillance time or personnel required. This study provided data on total and site-specific infection rates for a wide range of small to large hospitals. When stratified into subgroups (based on teaching status and hospital size), infections rates in this study were comparable with those of the National Nosocomial Infection Surveillance program, and showed a trend of increasing rates of nosocomial bloodstream and surgical wound infections.

Significance of isolated hepatitis B core antibody in blood donors.

BACKGROUND: About 25% of blood donors who test positive for antibody to hepatitis B core antigen (anti-HBc) have no other positive hepatitis B serologic results. Because of the potential importance and diagnostic uncertainty of this test result, we studied its significance by assessing the serologic response to hepatitis B vaccine in donors with an isolated anti-HBc pattern. METHODS: Specimens from 300 blood donors that were positive for anti-HBc by enzyme immunoassay were tested for anti-HBc by radioimmunoassay and for antibody to hepatitis B surface antigen (anti-HBs). A subgroup of 37 were further studied after administration of hepatitis B vaccine and compared with 34 similarly vaccinated age- and sex-matched seronegative controls. Measurements of anti-HBs were made at vaccination and 1, 2, 4, 8, 25, and 30 weeks after initial vaccination. RESULTS: Among 300 donors who tested positive for anti-HBc by enzyme immunoassay, the radioimmunoassay for anti-HBc was negative in 76 (25.3%) and the test for anti-HBs was negative in 104 (34.7%). Significant differences were observed for radioimmunoassay anti-HBc and anti-HBs titers, alanine aminotransferase, and male-female ratios between four distinct serogroups (A through D) defined by the combination (positive/negative) of radioimmunoassay anti-HBc and anti-HBs results. No significant differences between the study and control groups were observed in the magnitude of anti-HBs responses at any of the six postvaccine testing periods. CONCLUSIONS: Isolated anti-HBc in US blood donors is usually a false-positive result, regardless of the titer.

Comparative evaluation of serum CA 195 and carcinoembryonic antigen in metastatic carcinoma.

BACKGROUND: Carcinoembryonic antigen (CEA) is a well-described human tumor-associated antigen most useful clinically in colon cancer. However, the clinical usefulness of CEA is limited by the marker's overall poor specificity and low sensitivity in patients with minimal disease. CA 195 is a recently discovered human tumor-associated glycoprotein that can be measured in serum using an immunoradiometric assay. CA 195 is expressed on the membrane of human colon cancer cells and shares an epitope with the Lewis A blood group antigens. The authors initiated a study to compare the clinical utility of serum CA 195 with CEA in patients with advanced cancer. A control population was studied to assess the effects of age, gender, alcohol, and tobacco on the measured levels of serum CA 195. METHODS: Using a solid-phase two-site immunoradiometric assay, serum CA 195 and CEA levels were measured in 71 control subjects and 167 patients with a prior diagnosis of cancer. The tumor histologic types included breast cancer, 49 patients; colon cancer, 38; prostate cancer, 24; lung cancer, 22; gastrointestinal noncolon cancer, 7; and miscellaneous, 27. Among patients with a history of cancer, 124 (74%) had active metastatic disease, and 43 (26%) were without evidence of active disease. The control population was composed of subjects without a history of malignancy. Clinical data collected from them included age, gender, smoking history, and alcohol consumption. RESULTS: In this laboratory, the normal ranges established for CA 195 and CEA in the control group were: 0.0-8.3 U/ml and 0.2-4.2 ng/ml, respectively. In the control subjects, the serum CA 195 level, unlike that of CEA, was not affected by age, gender, alcohol consumption, or tobacco use. In the study population, CA 195 had either equivalent or inferior specificity and sensitivity to CEA in all tumor types. A determination of the additive specificity and sensitivity of CA 195 and CEA did not significantly improve its clinical utility compared with CEA alone. However, CA 195 was significantly elevated in three patients with a prior history of colon cancer thought to be without evidence of active disease. Because all three of these patients had a relapse within the next 1-15 months, CA 195 might identify early relapses of colon cancer in some patients. CONCLUSIONS: Based on these results, it was concluded that CA 195 is not superior to CEA as an indicator of disease activity in advanced colon cancer or other solid tumors. However, studies utilizing CA 195 in the detection of early relapses of colon cancer may be warranted. A review of the English literature revealed that CA 195 might be a useful marker in pancreatic cancer.

The effect of skin disinfection materials on reducing blood culture contamination.

Contaminated blood cultures may cause results to be misinterpreted, create unnecessary work for the laboratory, and increase costs. Disinfection of the venipuncture site is considered to be necessary for preventing contamination, although there is little information about the effectiveness of using different disinfection materials. The use of 70% isopropyl pads and povidone iodine saturated swabs (conventional method) was compared with the use of a 70% isopropyl/10% acetone scrub and povidone iodine dispenser (PREP method) for skin disinfection. Blood culture "kits" were prepared--bags containing collection tubes, instructions, and either conventional or PREP materials and were distributed randomly. The contents were concealed by a cover to prevent the user from selecting a specific type of decontamination kit. The kits were identified in the laboratory by color-coded labels on the collection tubes. Among 1,546 specimens evaluated, the contamination rate observed with conventional disinfection was significantly higher (4.6%; N = 763) than with PREP materials (2.2%; N = 783, P = 0.011) and was equivalent to the preceding 6-month contamination rate (4.7%). The lower contamination rate may be associated with greater effectiveness of a scrub or isopropyl/acetone solution, or both. Decontamination materials may have a significant impact on reducing blood culture contaminants from skin flora.

A nationwide quality assurance program can describe standards for the practice of pathology and laboratory medicine.

An important component of quality assessment is the analysis of peer group comparisons, although little data are available for evaluation. We developed and tested six interinstitutional quality indicators related to Pathology and Laboratory Medicine among 36 institutions. Results showed that the mean frequency of intraoperative frozen section consultations (6.0%), sensitivity of fine needle aspiration cytology diagnosis (87%), nosocomial infections (5.0%) and average cross-match to transfusion ratio (2.1%) was comparable with previous studies, but the range of values was large. The median stat laboratory turnaround time of approximately 1 hr for CSF cell count, glucose, protein and gram smear was considerably longer than expected from previous investigations, and was longer for larger institutions. Analysis of serious laboratory reporting errors showed the lowest number detected by individuals working in transfusion medicine, and highest numbers among hematology workers. We conclude that interinstitutional comparison of data from quality assurance programs can be used to describe performance standards related to the quality and effectiveness of care.

Solitary blood cultures as a quality assurance indicator.

For patients with suspected bacteremia, at least two separate blood cultures are recommended to achieve maximum sensitivity and to properly interpret results. Since a single blood collection may signify an improper procedure with serious consequences if the diagnosis of blood stream infection is missed, we investigated this problem with studies at three teaching hospitals (A, B, and C) and by a survey of 38 other hospitals. The incidence of solitary blood cultures ranged from 1 to 99% (median 26%) at the surveyed institutions. Among the cases investigated at hospitals B and C, between 10 and 30% of solitary blood cultures were not clinically indicated, while most of the others were caused by the physician not knowing that one culture was insufficient or by failure to complete the diagnostic plan. Focused concurrent intervention at hospital B was associated with reductions in solitary blood cultures from 40.0 to 24.6% (p = 0.045) and a decline in those not indicated from 38.1 to 12.5% (p = 0.192). Global educational efforts at hospital A were associated with a decrease in solitary blood culture rates from 52 to 37% (p = 0.016). These results show that blood culture practice varies widely among institutions in spite of consensus recommendations for proper specimen collections. We estimate that, nationwide, up to 18,000 etiologic diagnoses of bacteremia are missed annually because of this problem. Monitoring institutional solitary blood cultures is recommended as a test utilization indicator and as the basis for improving blood culture practice.