Questioning Dogmas in Microbiology Paul C. Schreckenberger, Ph.D Director, Clinical Microbiology Lab University of Illinois at Chicago [email protected].

Questioning Dogmas in Microbiology

Paul C. Schreckenberger, Ph.D

Director, Clinical Microbiology Lab

University of Illinois at Chicago

[email protected]

Department of Pathology:

Department of Pathology:Department of

Pathology:

Department of Pathology:Department of

Pathology:

Department of Pathology:Department of

Pathology:

Department of Pathology:Department of

Pathology:

Department of Pathology:

The University of Illinois at Chicago Medical Center

– Urban Medical Ctr.– 450 Bed Teaching

Hospital– 400K Ambulatory Visits – 43 Ancillary Departments

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, 1997 - CSF– Meredith FT et al. JCM 35:3109, 1997 - CSF– Dunbar SA et al. JCM 36:1617, 1998 - CSF

Broth Culture

• Savings at UICMC - 1998Direct Cost SavingsWounds - 3084 x .32 (EB) = $ 990CSF - 3114 x .32 (EB) = 996Body fluid - 1905 x .32 (EB) = 610Stools - 1013 x .45 (GN, HE) = 456

$3,052

Broth Culture

• Savings at UICMC - 1998Indirect Cost SavingsDid not have to set up or exam 9116 broth tubesDid not report bogus findings leading to additional testing or therapy of patients

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

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.”

Screening Sputum

• References for using criteria of >10 SEC to reject sputum:1. Murray PR, Washington II JA: Mayo

Clinic Proc. 50:339-344, 19752. Wong LK et al: JCM 16:627-631, 1982

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

Number of RespiratorySpecimens Accepted for Culture

0

200

400

600

800

1000

1200

1400

1600

1800

FY 94 FY 95 FY 96 FY 97 FY 98 FY 99

Sputum

Bronch

Trach

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

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

UICMCUICMC

0

50

100

150

Aug-99

Sep-99

Oct-99

Nov-99

Dec-99

Jan-00

Feb-00

Mar-00

Apr-00

Endotrach Screening

Accept Reject SEC Reject LOC

Assessing the Quality of Sputum Specimens for AFB Culture

• 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

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

Correlation of PMN to AFB PositivityMcCarter and Robinson AJCP 1996

No. Specimens PMN Present PMN Absent

Total – 724 665 (91.9) 59 (8.1)

AFB smearPos – 51

47 (92.2) 4 (7.8)

AFB culturePos – 121

109 (90.1) 12 (9.9)

Correlation of PMN to AFB PositivityMcCarter and Robinson 1996

• Based on annual volume of 1378 Sputa and absence of PMNs in 8.1%,

• Annual savings of $1,802.00 (based on incremental costs of $3.55 for AFB smear and $12.54 for AFB culture)

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 director2. If patient is symptomatic, lab will accept three more for up to a maximum of six specimens

Guidelines for AFB Cultures

• Once three smears are positive 1. Stop accepting respiratory cultures for one month to allow time for cultures to grow2. Smear requests honored any time as

direct smears (not concentrated) until three consecutive negatives are received

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 36:467-469, 1998– Divinagracia RM et al. Chest 114:681-684, 1998– Peterson EM et al: JCM 37:3564-3568, 1999

Distribution of first positive specimen in patients with >3 AFB specimensNelson S. et al. JCM 36:467, 1998

CollectionOrder

CulturePos

SmearPos

SmearNeg

1st 80(67) 41(73) 39(61)

2nd 33(28) 8(14) 22(34)3rd 7(5) 4(7) 3(5)

4th or later 0(0) 3(6) 0(0)

Total 120 56 64

AFB Smear Results Among 43 Patients Culture Pos for MTB

Peterson et al. JCM 37:3564, 1999

CollectionOrder

ConcentratedSmear Pos

DirectSmear Pos

1st 31(72.1) 24(55.8)

2nd 4(9.3) 8(18.6)3rd 3(7.0) 2(4.7)

Total 38(88.4) 34(79.1)

Guidelines for Release from Isolation• 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

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

Stool Cultures - Additional Rules• 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

Guidelines for Submitting Stool for C. difficile

• Test should only be requested when following criteria are met:1. Antibiotic within 2 mos. prior to diarrhea2. Diarrhea water/profuse: 6 episodes in 36h3. Absence of other diagnosis for diarrhea

Stool for C. DifficileRepeat 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 therapyReference: Barenfanger J, Khardori N: Clin Micro Newsl 18:142, 1996

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