Workshop held at CACMID 1996.

Consensus Report: Blood
This information was the outcome of the workshop breakout discussion. A complete copy of the 1996 Standards of Practice Workshop binder is available by contacting the Registrar of the Canadian College of Microbiologists.

Delayed Bottle Entry:
Discussion centered on current manufacturer's guidelines for delayed entry of bottles to automated non-invasive instruments and to the manual ISOLATOR system.

Fungal Culture Bottles: Isolation of Candida and Cryptococcus species appears to be adequate in regular blood culture aerobic bottles. There is increasing evidence in the litreature to support this protocol. One advantage is that the one system can support the growth of both bacteria and yeast. The ISOLATOR system remains the gold standard for recovery of systemic and dimorphic fungi.

Mycobacterial Culture: MAI - the BACTEC 13 A bottle remains the gold standard for recovery of MAI.

Mycobacterium tuberculosis: There is limited experience yet with the fluorescent and non-radiometric commercial systems for the rapid detection of Mycobacterial species from blood. There was some consensus that the blood should be processed by the ISOLATOR system before inoculation into broth or solid media.

Media Supplements:

BacT/Alert-FAN - An abstract Ps76 CACMID 1996 submitted by A.P. Gibb et al. concluded that FAN bottles are superior to the standard bottles for recovery of Gram negative bacilli. See also Journal of Clinical Microbiology Sept. 1996. L. MacDonald et al. Vol 34, No. 9: 2180-2184.
BACTEC- Resins - There was agreement with the previous reports of increased recovery in bacteria in resin supplemented bottles.

Retention of an Anaerobic Bottle: There was general aggreement that the anaerobic bottle increased recovery of facultative organisms and allowed the growth of anaerobes without setting stringent guidelines in place to use anaerobic bottles only for abdominal surgery, ob/gyn patients, etc.

Prolonged Incubation Times: Discussion ranged on the utility of extending incubation protocals. With the exception of clinical requests for Bartonella and Brucella, there did not seem to be evidence to support prolonged incubation periods.

Reduced Incubation Times: The question of reducing incubation times to less than 5 days was raised, i.e. 3 days. No doubt there will be a few abstracts at CACMID next year investigating this issue. top

Consensus Report: Urine
This information was the outcome of the workshop breakout discussion. A complete copy of the 1996 Standards of Practice Workshop binder is available by contacting the Registrar.

Consensus was difficult to achieve in the Urine breakout group, as has been shown to be in surveys of Canadian practice by regulatory bodies, This is probably due to the wide variety of private, public health and hospital based laboratories represented by the Workshop participants. However, extensive discussions within the group emphasized the importance of the following areas for future review:

Screening for pyuria: It was recognized that for diagnosis of uncomplicated urinary tract infections, there is little utility in culturing specimens which show no evidence of pyuria (leukocyte esterase, protein, nitrite by dipstick). However, there were at least two difficulties in implementing such a screen:
a) Private laboratories or other laboratories on a fee-for service basis would prefer not to forego revenue from culturing specimens for routine culture. b) Some reliable mechanism to ensure culture of urines from complicated clinical cases (e.g., treatment failure, chronic or recurrent infection, urethral syndrome, etc.) would have to be put in place. This could be done through the use of ordering comments or "clinical order detail". Some computer systems and organizational structures do not handle these interactions effectively and reliably. The necessary components of such a system include an informed physician ordering the specimen as either routine screen or as a complicated case requiring culture, a process for transmitting this order accurately to the nurse or clerk who actually enters the order into the system, and an efficient mechanism for separating urines for screening and culture in the laboratory.

Units for Reporting: A wide variety of units for reporting quantitation cultures are used, with the majority using some form of "metric" unit such as >10⁸/L. A minority of laboratories use the SI unit rules >100 x 10⁶/L. It was commonly felt that the quantitative given did not influence the management of the infection, and a more important signal to the physician is the presence of a full identification and susceptibility profile. "If ID and sens are given by the lab, it must be important".

Dip Slides and "Easy Streak": There is only limited use of the urine dip or auto-streak media coated paddles, largely due to the delay that results from significant growth causing overlapping colonies and necessitating the subculture of the paddle. These devices, or alternatively, urine preservative transport systems, are only used where rapid transport to the laboratory (within 2 hours at room temperature) is possible.

Core Lab: The development of Core laboratories and their impact on Microbiology were discussed. It was felt that the core lab could handle such straightforward tests as screening for pyuria by urinalysis dipstick. It was also suggested that they might handle culturing with a single loop, and reporting out indol positive lactose fermenters as probable E. coli without a susceptibility. More complex investigations could be transferred to a full service Microbiology Laboratory.

Quality Assurance: It was agreed that improved guidelines for Quality Assurance as well as a collection of proven Quality Indicators was needed. Such Quality Indicators would cover the complete process from Physician Order to Final Report as well as impact on patient care outcomes.

Updates A simplified method reporting, intended to replace Fig. 1 for interpretation of midstream urines was discussed. This sheet can be added to the binder following Fig. 1.

Simplified Interpreted Report

• >10 x 10⁶/L 1-2 pathogens report identification and susceptibility
• if CNS, AHS, Lacto, Diphs, report "Mixed Growth of Doubtful Significance" and request repeat
• With multiple organisms add comment ">90% of UTI are caused by single pathogens"
• < 10 x 10⁶/L report "No Significant Growth"
• if 0 report "No growth"

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1. BACTERIOLOGY:

Routine Enteric Culture: Should NOT be done routinely if the patient has been hospitalized greater than or equal to 3 days. Maximum number of specimens should be 1/day to a total of 2.

Minimal Media Requirements: MAC, XLD, Selenite F, Mac-Sorbitol, Blood-free Campylobacter medium (minimal, most cost effective combination for routine enteric culture).

C. difficile Testing: Need to educate clinicians to ensure testing is only requested on appropriate patients (i.e. history of antibiotic therapy, and clinically significant diarrhea). Gold standard is still the cytotoxin test, although EIA is an acceptable alternative. Latex agglutination testing on direct stool is not recommended and culture has limited diagnostic applicability due to extended time required for detecting growth and then testing isolates for toxin production. Maximum numbers of specimens per patient should be 1/day to a maximum of three. Test of cure should not be done routinely.

EHEC: Direct testing of stool for verocytoxin is recommended, as some EHEC strains are Sorbitol-fermenters and therefore would be missed using only culture with Mac-sorbitol plates. Assessment of incidence is suggested; if year round distribution is observed, all stools all year long should get Mac-sorbitol plates, otherwise all stools in peak season should be Mac-sorbitol plates. Reports demonstrate that even non-bloody stools can contain EHEC.

VRE: Although not an enteric pathogen per se, it was a topical issue of discussion regarding screening of stool for VRE. Recommend screening high-risk population (e.g. C. difficile diarrhea and dialysis patients) for VRE carriage. CNA containing 6 ug/ml Vancomycin or Enterococcal agar were recommended as most effective screening medium. The role of enrichment broth (e.g. CNA + 6 ug/ml vancomycin) remains to be clarified.

Sensitivity Testing: The need to report antibiotic sensitivity results was discussed. It was recommended that testing and reporting should follow NCCLS or LPTP recommendations, and that routine sensitivity testing should be performed particularly since resistance has increased among the routine enteric pathogens (especially in returned travellers). Sensitivity testing is unnecessary for Campylobacter spp. or C. difficile.

Reporting: It is critical to state which pathogens were tested for (e.g. report: No Salmonella , Shigella, Yersinina, Campylobacter or EHEC detected), such that if the clinical history (e.g. travel history) warrants, the clinician can request testing for nonroutine pathogens (e.g. Vibrio, or Aeromonas). If the report does not indicate which pathogens were looked for, wrong assumptions could be made by the clinician.

Diagnostic Testing: Only recommended for outbreak situations. Although EIAs are good (e.g. for Rota virus), Electron microscopy provides the most cost-effective approach, since it offers the widest range of detection (detects Rota virus as well as small round enterics, Norwalk, Adenovirus, etc.) Specimens for EM should not be sent in viral transport medium, rather a direct stool sample in a sterile container is adequate.

Microscopy:
Recommend that specimens that are processed for parasitology should include:
1) Acid-fast smear of direct stool for cryptosporidia, and cyclospora,
2) Wet prep of concentrated specimen and
3) Permanent smear (Trichrome or Iron-hematoxylin) should be done.

Must ensure that fixative is compatible with staining method (SAF is most widely used). The value of the combined Acid-fast/Iron-hematoxylin stain method was confirmed.

Reporting: Issues of concern surrounded reporting of "non-pathogens". It was agreed that qualifying guidelines should be included in the report. Parasites should be reported as "pathogens" (e.g. E. histolytica), "non-pathogens" (e.g. E. coli) or "potential-pathogens" (e.g. Cryptosporidium parvum may be pathogenic in immunocompromised patients).

The need for obtaining information on the requisition is critical. Methods to achieve this are difficult. It was suggested that the only way to effectively achieve this is to reject specimens without clinical details. Recommended "pleasant rejection" as a means of leverage. It is initially painful, but once in place is the most effective method.
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Workshop Index