The impact of laboratory reporting practice on antibiotic utilisation

Microbiology reports are often misinterpreted by clinicians, which may lead to inappropriate antibiotic prescribing. Restricted release of susceptibilities combined with interpretative comments, can have a positive impact on the level of appropriate antibiotic use. Such a system requires two-way communication between the laboratory and the clinician and the laboratory's reporting practices should encourage such communication. The production and transmission of clinically relevant microbiology reports should be an integral part of infectious disease management programmes in hospitals.

On the need for massive additional shielding of a catheterization laboratory for the implementation of high dose rate 192Ir intravascular brachytherapy

PURPOSE

There is a widespread belief in the cardiology and radiation oncology community that high dose rate 192Ir intravascular brachytherapy cannot be implemented without massive additional shielding of the conventional catheterization labs. The purpose of this work is to show that this is a myth, which is not based on sound radiation protection principles.

METHODS

Exposure rates in air were calculated for a variety of point and line sources of 192Ir. Exposures per treatment at different distances from the source were calculated for a typical intravascular brachytherapy treatment of a 15-Gy dose at a radial distance of 2 mm from the source and for source lengths in the range of 0 to 10 cm. Additionally, exposure rates outside the catheterization lab were calculated for various lead shielding thicknesses typical of conventional X-ray facilities. These rates were used along with the NCRP recommendations on radiation facility design to assess shielding requirements.

RESULTS

For a treatment dose of 15 Gy at 2 mm, the occupational exposure per treatment at 2 m in air without any tissue attenuation or shielding was 7.8 mR for a lesion length of 3.0 cm. This exposure/treatment is independent of the dose rate or the activity of the source. However, it increases as lesion length is increased, increasing from 5.4 to 24.9 mR as lesion length increased from 2 to 10 cm. Exposures in unrestricted areas outside the catheterization lab using the NCRP shielding rationale can be kept below 2 mR per treatment and using appropriate workload, use, and occupancy factors below 2 mR per week.

CONCLUSIONS

The feasibility of implementing a high dose rate 192Ir intravascular brachytherapy program in a catheterization laboratory is totally independent of the dose rate or the activity of the source. If it is feasible to implement 192Ir brachytherapy in a conventional catheterization lab using low activity 192Ir seeds, then it is also feasible to do so with a high activity 192Ir afterloader.

Diagnostic errors in surgical pathology

This article discusses the concept of diagnostic error in surgical pathology and how surgical pathologists attempt to decrease diagnostic error. Emphasis is placed on currently used error reduction methods.

What does a clinician expect from a microbiologist? Towards an effective joint policy

What a clinician needs from a microbiologist and microbiological service depends on the specialty. To provide a diagnosis of infection, the service should organize and also follow-up the specimen transport, microbiological examination and antimicrobial susceptibility testing together with antigen detection and other modern test technology. A manual describing the local service and including guidelines should be placed in every department. At the same time a clinician should be familiar with clinical syndromes and causative micro-organisms, in order to be able to ask for the correct investigation. Only with continuous interchange of information by both parties is an effective joint policy possible in daily routine work.

A survey of factors affecting the recruitment and retention of Medical Laboratory Scientific Officers in Pathology

OBJECTIVE

To survey the perceptions and attitudes of Medical Laboratory Scientific Officer (MLSO) staff in Pathology to explain difficulties in recruitment and retention and inform attempts to solve the difficulties.

DESIGN

Questionnaire to a defined group of MLSOs.

SETTING

The Laboratory Medicine Directorate, Aberdeen Royal Infirmary.

SUBJECTS

MLSO1 and MLSO2 staff currently or recently working in Pathology (histopathology) in Aberdeen.

RESULTS

The survey return rate was 100%. Opportunities for career development in Pathology are poor, this being the worst feature of working in Pathology. Remuneration is poor and is a disincentive to remaining in the speciality. MLSOs feel undervalued in relation to other health care workers. Many have concerns about laboratory organisation, but find a sociable and supportive environment that provides job satisfaction. Staff seek work in other laboratories because of opportunities for promotion, learning new skills and increased pay, although pay in specialities other that Pathology is greater only because of shift working in these disciplines. There is a need to increase public awareness of MLSOs' central role in providing and maintaining excellence in Pathology services.

CONCLUSION

MLSO staff have concerns about their career structure and salary scales. The responsibility of MSLOs in Pathology for quality assurance and managing MLAs is not recognised. These factors form a disincentive to working in Pathology laboratories and threaten our ability to staff the service and to maintain the turnover and quality of Pathology services. These issues require to be addressed nationally and rapidly to prevent the continuing decline in MLSO numbers. Matters of local organisation might be addressed by trusts and departments, but recognition of the need to resource changes would require reflection in budgets.

Lessons learned in decommissioning medical facilities

In decommissioning medical research buildings at this institution, most areas surveyed were not contaminated above NRC 1993 release limits. Most contamination found was fixed. Wipe tests were inefficient at assessing removable contamination. An initial approach to surveying such a facility should begin with limited sampling emphasizing fixed contamination detection. Recent NRC guidance on decommissioning suggests that the requirements are becoming less stringent for medical facilities. This seems to support our limited decommissioning survey strategy for medical research buildings where radioisotopes have been used.

Observations on centrifugation: application to centrifuge development

This report outlines the background to the development of an automated, serial, discrete centrifuge, reporting on the criteria considered essential in such an instrument. We established the criteria by examining the detailed logistics of centrifuge operation in a hospital laboratory. The mean sample load per run, using six centrifuges, was 13.6 samples, and the user-selectable cycle time ranged from 00:01:10 to 00:12:33 (hours:minutes:seconds) with a fixed g value of 1050. During the laboratory working window, (0900-1700), only 50% of the centrifuge capacity was utilized and more than one-third of the sample workload was delayed for >5 min because the centrifuges were not emptied promptly. In addition, 35% of the sample workload was centrifuged for less than the time prescribed in the operational specifications. Based on these findings, we designed a new continuous, serial centrifuge to overcome some of the deficiencies noted in the logistics study. The centrifuge operates continuously, nominally treating 150 samples/h, with a cycle time of 5 min at 1,000 g. The cycle time and g value are variable between limits, and their selection governs the throughput rate. Each sample is centrifuged separately in individual rotors mounted in a sturdy carousel with a periphery that traverses a load/unload station. There is no sample delay because of operator absence, and the capacity is fully utilized. The centrifuge can operate in a stand-alone capacity or has the capability of being integrated into a sample preparation system or as a direct front end for high-throughput analyzers.

Novel microtiter plate format for testing germ tube formation and proposal of a cost-effective scheme for yeast identification in a clinical laboratory

The germ tube test is most widely used for presumptive identification of Candida albicans. Conventional testing is relatively time-consuming due to the hands-on time involved in preparing and viewing each isolate. In order to reduce work-load and costs we have developed a novel microtiter plate test format that offers several advantages: (i) use of removable strips of microtiter wells placed in lockwell frames, (ii) only one pipetting step for each isolate, (iii) direct micromorphological evaluation using an inverse microscope, (iv) use of a novel synthetic germ tube test medium, (v) reduction of the inoculum, permitting testing of minute colonies, (vi) thus, testing of different colonies in potentially mixed primary cultures of clinical specimens is encouraged and facilitated. Implementing this microtiter based germ tube test with simultaneous trehalase test for presumptive identification of Torulopsis (Candida) glabrata, we propose an identification scheme including this test format. This has been implemented in our routine laboratory permitting cost-effective presumptive identification of almost all clinically relevant yeast species.

[Cross-contamination of Mycobacterium tuberculosis culture in clinical laboratories]

For many years, it has been thought that positive culture of M. tuberculosis is a definitive diagnostic evidence of tuberculosis and cross-contamination of M. tuberculosis culture in clinical laboratories is rare. However recently introduced RFLP analysis has enabled us to identify a strain of M. tuberculosis, and many cases of the cross-contamination in clinical laboratories confirmed by RFLP analysis have been reported. In this report, we present the first case of the cross-contamination confirmed by RFLP in Japan. In our case, 5 patients without any personal link to each other were suspected based on clinical findings to have cross-contaminated results of M. tuberculosis culture. All their specimens were processed on the same day, and were smear negative and culture positive with only a small number of colonies (less than 8 colonies). The sputum from the suspected source of contamination processed on the same day was strongly positive for AFB smear and heavily culture positive. The RFLP patterns of these 6 patients were identical, so it was concluded that the positive cultures of the sputum from the 5 patients who were not expected to be culture positive on clinical findings were caused by the cross-contamination in our hospital laboratory. We review all the charts of patients with M. tuberculosis culture positive results in the same year of this case, but we didn't find no other cases suspected of the cross-contamination. Then we reviewed the literature of M. tuberculosis culture cross-contamination. The patterns of the cross-contamination are divided into two. One is associated with malfunction of a sampling needle in the BACTEC 460 system and the other associated with the initial processing of the specimens, mostly involving reagents such as NaOH solution. Cross-contaminated specimens are usually smear negative with only a few colonies (less than 5), and processed just after the source specimen of the contamination in most reported cases, but not in all. In almost half of them the cross-contamination results had significant influence on the clinical management. The frequency of the cross-contamination is estimated around 1% of the patients with M. tuberculosis culture positive results. For early detection of the cross-contamination, not only clinicians but also laboratory staffs have important role and close cooperation between them is mandatory. To prevent the contamination, it is advisable to process smear positive and probable culture positive specimens separately from others, and not to use a large same container of reagents for processing of different specimens.

Multicenter evaluation of antimicrobial resistance to six broad-spectrum beta-lactams in Colombia: comparison of data from 1997 and 1998 using the Etest method. The Colombian Antimicrobial Resistance Study Group

The minimum inhibitory concentrations of six broad-spectrum beta-lactam antimicrobial agents were determined in 1998 by use of the Etest versus a total of 823 bacteria in 11 Colombian hospital laboratories. These data were compared with results of a similar study conducted in 1997. The organisms tested included 532 recent clinical isolates of Enterobacteriaceae, 108 Pseudomonas aeruginosa, 94 Acinetobacter species, and 89 oxacillin-susceptible Staphylococcus aureus. Extended-spectrum beta-lactamase production was noted among 27.8 to 33.9% of Escherichia coli isolates and 41.7 to 46.7% of Klebsiella spp. isolates. Hyperproduction of Amp C cephalosporinases was observed with 10.5 to 31.4% of isolates of Enterobacter spp., Serratia spp., and Citrobacter spp. An increase in resistance to all of the beta-lactams was observed among Enterobacteriaceae, Acinetobacter spp. and P. aeruginosa when 1998 results were compared with those obtained in 1997. The overall rank order of activity of the six beta-lactams tested in 1998 versus all clinical isolates was imipenem (93.2% susceptible) > cefoperazone/sulbactam (84.1%) > cefepime (80.9%) > ceftazidime (70.7%) > aztreonam (65.7%) > cefotaxime (65.6%). In contrast, the rank order of these same agents tested against a similar collection of Colombian isolates in 1997 was imipenem (96.6% susceptible) > cefepime (93.6%) > cefoperazone/sulbactam (90.5%) > cefotaxime (74.9%) > aztreonam (74.3%) > ceftazidime (73.2%).

Review of the clinical activity of medical microbiologists in a teaching hospital

BACKGROUND

The clinical interactive role of medical microbiologists has been underestimated and the discipline is perceived as being confined to the laboratory. Previous studies have shown that most microbiology interaction takes place over the telephone.

AIM

To determine the proportion of clinical ward based and laboratory based telephone interactions and specialties using a microbiology service.

METHODS

Clinical microbiology activity that took place during November 1996 was prospectively analysed to determine the distribution of interactions and specialties using the service.

RESULTS

In all, 1177 interactions were recorded, of which nearly one third (29%) took place at the bedside and 23% took place on call. Interactions involving the intensive treatment unit, general ward visits, and communication of positive blood cultures and antibiotic assays were the main areas of activity identified. There were 147 visits to 86 patients on the general wards during the study, with the number of visits to each individual varying from one to eight. The need for repeated visits reflected the severity of the underlying condition of the patients. Ward visits were regarded as essential to obtain missing clinical information, to assess response to treatment, and to make an appropriate entry in a patient's notes.

CONCLUSIONS

Ward visits comprise a significant proportion of clinical microbiology interactions and have potential benefits for patient management, service utilisation, and education.

An audit of error rates in a UK district hospital transfusion laboratory

We have audited the error rates of our transfusion laboratory and compared these with error rates reported in the transfusion literature. Error rates were calculated using workload data from the department. The majority of errors that were detected were preanalytical and related to inadequate or incomplete data provided on the sample or request form. These errors were all corrected prior to any further action being taken on that request. The main analytical errors were transcription errors in entering patient identification information into the laboratory computer by transfusion staff together with the incorrect performance of blood group testing. For postanalytical errors the main errors were failure of nursing staff to follow procedures for the collection of blood components prior to transfusion. There were no serious consequences identified of the errors detected in this study. It was difficult to compare these results with those published in the literature in view of the different methodologies that have been reported when error rates have been determined. A standard method should be developed in the UK for calculating error rates so that laboratories can benchmark their performance against comparable organizations.

Neonatal group B streptococcal disease in Finland: a ten-year nationwide study

BACKGROUND

Group B Streptococcus (GBS) is the most common cause of invasive infections in newborns. GBS bacteria are typed on the basis of capsular polysaccharides or surface-localized proteins. Both polysaccharides and protein antigens have been suggested as potential vaccine candidates.

METHODS

A prospective nationwide laboratory-based study of invasive GBS infections in children younger than 3 months of age was conducted in 1985 through 1994. Isolates were serotyped by immunodiffusion in agar gel with HCl extracts and rabbit antisera. Clinical diagnoses and case fatalities were verified from the patient records or the national hospital discharge register.

RESULTS

There were 485 cases registered during the 10-year period. The incidence of disease was 0.76/1000 live births. The case fatality rate was 8.0%. Of the 485 cases 398 (83%) were early onset and 87 (17%) late onset infections. The most common clinical diagnosis was bacteremia (77%) without an identified focus of infection. Other diagnoses included meningitis (17%), pneumonia (3%), osteomyelitis or septic arthritis (2%), pyelonephritis or cellulitis. Serotyping of 395 isolates revealed that 47% were of serotype III or III/R, 23% of Ia/c, 11% of Ib, 6% of II/R, 8% of IV, 1% of V and 7% were nontypable.

CONCLUSIONS

The clinical picture of GBS disease and serotype distribution are similar to what has been reported from other countries. Serotypes III and III/R dominated (47% of all infections), especially in late onset disease. On the basis of these results a GBS vaccine including at least the Ia, Ib, II and III components would provide coverage against 88% of GBS serotypes causing neonatal disease in Finland.

[Introduction and some problems of the rapid time series laboratory reporting system]

We introduced an on-line system of biochemical, hematological, serological, urinary, bacteriological, and emergency examinations and associated office work using a client server system NEC PC-LACS based on a system consisting of concentration of outpatient blood collection, concentration of outpatient reception, and outpatient examination by reservation. Using this on-line system, results of 71 items in chemical serological, hematological, and urinary examinations are rapidly reported within 1 hour. Since the ordering system at our hospital has not been completed yet, we constructed a rapid time series reporting system in which time series data obtained on 5 serial occasions are printed on 2 sheets of A4 paper at the time of the final report. In each consultation room of the medical outpatient clinic, at the neuromedical outpatient clinic, and at the kidney center where examinations are frequently performed, terminal equipment and a printer for inquiry were established for real-time output of time series reports. Results are reported by FAX to the other outpatient clinics and wards, and subsequently, time series reports are output at the clinical laboratory department. This system allowed rapid examination, especially preconsultation examination. This system was also useful for reducing office work and effectively utilize examination data.

Evaluation and implementation of the gel test for indirect antiglobulin testing in a community hospital laboratory

BACKGROUND

The gel test, developed by Lapierre in 1984, was designed to standardize antiglobulin testing while improving sensitivity and specificity of the method.

PRINCIPLE

Anti-human serum immunoglobulin G (IgG) mixed with Sephadex G100 (gel phase) in a microtube traps red cell-IgG agglutination complexes during migration through the gel in a centrifugation step. Agglutination complexes are visibly detectable at various levels in the microtube as an inverse function of antibody coated on red cells. Unsensitized red cells form a cell pellet at the base of the microtube.

OBJECTIVE

To determine if indirect anti-human globulin testing could be standardized and simplified by replacing the tube test with the gel test without compromising quality or increasing costs.

SETTING

A medium-sized community hospital.

RESULTS

In a blinded retrospective study, we used patient sera (n = 40), which included 10 positive specimens containing 18 known antibodies. Sixteen antibodies were detected and identified with the tube method (1 anti-D and 1 anti-C not detected). By the gel test, 18 antibodies were detected and identified. All negative samples showed 100% concordance. Favorable results were obtained in a nonblinded prospective correlation study (n = 121). Our technologists found the gel test easier to read and more reproducible and reliable than the tube method; they also found increased sensitivity for detecting weakly reacting antibodies. We successfully introduced the gel test into our laboratory as the standard method for indirect antiglobulin testing. Following implementation, improved personnel management was achieved.

CONCLUSIONS

The gel test is a reliable and advantageous method and is appropriate for routine use for detection and identification of alloantibodies in a community hospital transfusion service laboratory.

Most Enterobacter aerogenes strains in France belong to a prevalent clone

The aim of this study was to determine the distribution in France of the Enterobacter aerogenes prevalent clone isolated in the hospitals of the Marseille area (A. Davin-Regli, D. Monnet, P. Saux, C. Bosi, R. Charrel, A. Barthelemy, and C. Bollet, J. Clin. Microbiol. 34:1474-1480, 1996). A total of 123 E. aerogenes isolates were collected from 23 hospital laboratories and analyzed by random amplification of polymorphic DNA and enterobacterial repetitive intergenic consensus-PCR to determine their epidemiological relatedness. Molecular typing revealed that 21 of the 23 laboratories had isolated this prevalent clone harboring the plasmid encoding for extended-spectrum beta-lactamase of the TEM-24 type. Most isolates were susceptible only to imipenem and gentamicin. Their dissemination seems to be clonal and was probably the result of the general use of broad-spectrum cephalosporins and quinolones. Four isolates showed an alteration of their outer membrane proteins, causing decrease of susceptibility to third-generation cephalosporins and imipenem and leading to the critical situation of having no alternative therapeutic. The large dissemination of the E. aerogenes prevalent clone probably results from its good adaptation to the antibiotics administered in France and the hospital environment, particularly in intensive care units.

Radiation safety in the cardiac catheterization laboratory: operational radiation safety

The goal of the catheterization laboratory radiation safety program is to facilitate invasive cardiology while simultaneously reducing staff risks to an acceptable level. Achieving this goal requires a balance between the value of catheterization to the patient and the associated radiation risk to the staff. This article introduces the principles of radiation protection as applied in the catheterization laboratory. Prudent conformance to these principles will appropriately reduce radiation risk. Cathet. Cardiovasc. Intervent. 47:347-353, 1999.

Is the international normalised ratio (INR) reliable? A trial of comparative measurements in hospital laboratory and primary care settings

AIM

To determine the reliability of international normalised ratio (INR) measurement in primary care by practice nurses using near patient testing (NPT), in comparison with results obtained within hospital laboratories by varied methods.

METHODS

As part of an MRC funded study into primary care oral anticoagulation management, INR measurements obtained in general practice were validated against values on the same samples obtained in hospital laboratories. A prospective comparative trial was undertaken between three hospital laboratories and nine general practices. All patients attending general practice based anticoagulant clinics had parallel INR estimations performed in general practice and in a hospital laboratory.

RESULTS

405 tests were performed. Comparison between results obtained in the practices and those in the reference hospital laboratory (gold standard), which used the same method of testing for INR, showed a correlation coefficient of 0.96. Correlation coefficients comparing the results with the various standard laboratory techniques ranged from 0.86 to 0.92. It was estimated that up to 53% of tests would have resulted in clinically significant differences (change in warfarin dose) depending upon the site and method of testing. The practice derived results showed a positive bias ranging from 0.28 to 1.55, depending upon the site and method of testing.

CONCLUSIONS

No technical problems associated with INR testing within primary care were uncovered. Discrepant INR results are as problematic in hospital settings as they are in primary care. These data highlight the failings of the INR to standardise when different techniques and reagents are used, an issue which needs to be resolved. For primary care to become more involved in therapeutic oral anticoagulation monitoring, close links are needed between hospital laboratories and practices, particularly with regard to training and quality assurance.

Accuracy of the i-STAT bedside blood gas analyser

The performance of the i-STAT portable clinical analyser for measuring blood gases and pH was evaluated with reference to a conventional blood gas analyser (ABL520 Radiometer). Ninety-two samples from the routine blood gas analysis laboratory were chosen according to a wide distribution of partial pressure of carbon dioxide (Pa,CO2), partial pressure oxygen (Pa,O2) and pH and then analysed. All measurements were performed in duplicate by trained technicians from the central hospital laboratory. Differences between duplicate measurements were computed for Pa,CO2: (1.2 versus 0.4%), Pa,O2 (1.7 versus 1.1%) and pH (0.06 versus 0.02%), for the i-STAT and ABL520, respectively. pH and Pa,CO2 values measured with the i-STAT were very close to those obtained with the ABL520, the difference (mean+/-SD) being 0.006+/-0.018 and -0.13+/-0.17 kPa, respectively. Statistical analysis showed that the differences between analysers did not depend on values of pH or Pa,CO2. The performance of the analysers depended on the level of PO2. Below 15 kPa (n=48), the two systems gave nearly identical values, the mean difference was 0.01+/-0.37 kPa. Between 16 and 55 kPa (n=44), there was a systematic but small (-0.69+/-0.67 kPa) underestimation of Pa,O2 measured with the i-STAT (p<10(-8)). In conclusion, this study shows that blood gas analysis using the i-STAT portable device is comparable with that performed by a conventional laboratory blood gas analyser.