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Questioning Dogmas in Microbiology

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1 Questioning Dogmas in Microbiology
Department of Pathology: April 16, 1999 Department of Pathology: Department of Pathology: Department of Pathology: Department of Pathology: Questioning Dogmas in Microbiology Paul C. Schreckenberger, Ph.D Director, Clinical Microbiology Lab University of Illinois at Chicago

2 The University of Illinois at Chicago Medical Center
April 16, 1999 The University of Illinois at Chicago Medical Center Urban Medical Ctr. 450 Bed Teaching Hospital 400K Ambulatory Visits 43 Ancillary Departments

3 April 16, 1999 Broth Culture RULE: eliminate back-up broths except for Tissue and CSF with shunts -? References: Morris AJ et al: JCM 33:161, 1995 Derby P et al: JCM 35:1101, 1997 Silletti RP et al: JCM 35:2003, 1997 Sturgis CD et al. AJCP 108:217, CSF Meredith FT et al. JCM 35:3109, CSF Dunbar SA et al. JCM 36:1617, CSF

4 April 16, 1999 Broth Culture Savings at UICMC Direct Cost Savings Wounds x .32 (EB) = $ 990 CSF x .32 (EB) = Body fluid x .32 (EB) = Stools x .45 (GN, HE) = $3,052

5 April 16, 1999 Broth Culture Savings at UICMC Indirect Cost Savings Did not have to set up or exam 9116 broth tubes Did not report bogus findings leading to additional testing or therapy of patients

6 April 16, 1999 Screening Sputum RULE: perform Gram stain and evaluate under LPF (10 x). Reject if >10 SEC/LPF, unless also see a predominant field of WBCs assoc. with single morphotype of bacteria

7 Screening Sputum Cancel Culture, Charge for Gram Stain only
April 16, 1999 Screening Sputum Cancel Culture, Charge for Gram Stain only DON’T REQUEST REPEAT CULTURE: Add Comment: “specimen contaminated with epithelial cells represents oropharyngeal contamination further processing would yield potentially misleading results.”

8 April 16, 1999 Screening Sputum References for using criteria of >10 SEC to reject sputum: 1. Murray PR, Washington II JA: Mayo Clinic Proc. 50: , Wong LK et al: JCM 16: , 1982

9 Screening Sputum Sputum Quality Indicator UICMC
April 16, 1999 Screening Sputum Sputum Quality Indicator UICMC Using criteria of >25 SEC/LPF Rejected 20% (range 8-33%) - 1/91-6/92 QA monitor 12/95 showed rejection rate of 8% Using criteria of >10 SEC/LPF Rejected 39.4% (range 32-47%) - 1/96-5/97 Current Rate 35.4% (range 29-53) - 1/99-12/99

10 Number of Respiratory Specimens Accepted for Culture
April 16, 1999 Number of Respiratory Specimens Accepted for Culture

11 Screening Endotrachs Endotrach Quality Indicator UICMC
April 16, 1999 Screening Endotrachs Endotrach Quality Indicator UICMC Using same criteria as sputum screen (>10 SEC) Reject avg. of 4.1% endotrach specimens For FY 98 rejected only 51 specimens Using criteria of >10 SEC + NOS on Gram stain Reject avg. of 25% of endotrach specimens For FY 98 would have rejected 372 specimens

12 April 16, 1999 Screening Endotrachs RULE: specimens with >10 SEC/LPF, or no organisms seen on Gram stain (or yeast only) are not cultured Reference: Morris AJ et al: JCM 31:1027, 1993 Zaidi AK, Reller LB : JCM 34:352, 1996 Rand KH: Diagn Micro Infect Dis 27:55, 1997 Gilligan PH: Clin Micro Newsl 21:44, 1999

13 April 16, 1999

14 Assessing the Quality of Sputum Specimens for AFB Culture
April 16, 1999 Rejection criteria applied to bacterial cultures based on presence of SEC should not be applied to specimens for AFB culture Curion CJ et al:JCM 5:381, 1977 Havlik D, Wood GL: Lab Med 26:411, 1995 Isaac-Renton JL et al: AJCP 84:361, 1986 Laird AT: JAMA 52:294, 1909 McCarter YS, Robinson A: AJCP 105:769, 1996 Pohl AD Keim AC: Lab Med 24:25, 1993

15 Assessing the Quality of Sputum Specimens for AFB Culture
April 16, 1999 Assessing the Quality of Sputum Specimens for AFB Culture Rule: Sputum Specimens Containing No PMNs Are Not Routinely Smeared or Cultured for AFB Laird AT: JAMA 52:294, 1909 McCarter YS et al: AJCP 105:769, 1996 Wilson M: AJCP 105:665, 1996

16 Correlation of PMN to AFB Positivity McCarter and Robinson AJCP 1996
April 16, 1999 Correlation of PMN to AFB Positivity McCarter and Robinson AJCP 1996

17 Correlation of PMN to AFB Positivity McCarter and Robinson 1996
April 16, 1999 Correlation of PMN to AFB Positivity McCarter and Robinson 1996 Based on annual volume of 1378 Sputa and absence of PMNs in 8.1%, Annual savings of $1, (based on incremental costs of $3.55 for AFB smear and $12.54 for AFB culture)

18 Guidelines for AFB Cultures
April 16, 1999 Guidelines for AFB Cultures General Order: first morning sputum x 3. Accept only one specimen/day If first three concentrated smears negative 1. Must initiate consult with lab director 2. If patient is symptomatic, lab will accept three more for up to a maximum of six specimens

19 Guidelines for AFB Cultures
April 16, 1999 Guidelines for AFB Cultures Once three smears are positive 1. Stop accepting respiratory cultures for one month to allow time for cultures to grow 2. Smear requests honored any time as direct smears (not concentrated) until three consecutive negatives are received

20 Guidelines for AFB Cultures
April 16, 1999 Guidelines for AFB Cultures Once cultures are positive No new specimens for culture accepted for 1 month after date of positive culture References for No. of Sputum Necessary: Cascina A et al: JCM 38:466, 2000 Nelson SM et al: JCM 36: , 1998 Divinagracia RM et al. Chest 114: , 1998 Peterson EM et al: JCM 37: , 1999

21 April 16, 1999 Distribution of first positive specimen in patients with >3 AFB specimens Nelson S. et al. JCM 36:467, 1998

22 April 16, 1999 AFB Smear Results Among 43 Patients Culture Pos for MTB Peterson et al. JCM 37:3564, 1999

23 Guidelines for Release from Isolation
April 16, 1999 Patient Receiving effective chemotherapy Clinical Condition is improving Three consecutive sputum samples, collected on different days are AFB-smear-negative References : Telzak EE, et al: Clin Infect Dis 25:666, 1997 Iseman MD, et al: Clin Infect Dis 25:671, 1997 MMWR 43(suppl RR-13):1-132, 1994

24 April 16, 1999 Stool Cultures RULE: Restrict culture and O&P exam to outpatients and inpatients admitted <3 days RULE: Reject fungal culture on stools. Add statement: “Fungal cultures of stool have not been shown to be clinically useful.” Reference: Hines J, et al: Clin Infect Dis 23:1292, 1996

25 Stool Cultures - Additional Rules
April 16, 1999 Use MacConkey instead of EMB, allows you to screen for Yersinia without using CIN agar Eliminate enrichment broths except when looking for asymptomatic carriers Eliminate serotyping of Salmonella and Shigella, report presumptive result based on biochemical ID, send organism to State Health Lab for typing Place limitations on AST of stool pathogens

26 Guidelines for Submitting Stool for C. difficile
April 16, 1999 Guidelines for Submitting Stool for C. difficile Test should only be requested when following criteria are met: 1. Antibiotic within 2 mos. prior to diarrhea 2. Diarrhea water/profuse: 6 episodes in 36h 3. Absence of other diagnosis for diarrhea

27 Stool for C. Difficile Repeat Testing Criteria
April 16, 1999 Stool for C. Difficile Repeat Testing Criteria Negative results: Up to 3 stool specimens (not more than 1 per day) tested per patient Positive results: after a positive test, further testing only performed 7-10 days after completion of therapy Reference: Barenfanger J, Khardori N: Clin Micro Newsl 18:142, 1996

28 Questioning Dogmas in Microbiology
April 16, 1999 Questioning Dogmas in Microbiology “Nearly all experts agree that by the year 2000 bacterial and viral disease will have been wiped out” -Time Magazine February 25, 1966


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