Questioning Dogmas in Microbiology

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Questioning Dogmas in Microbiology
Department of Pathology
Department of Pathology
Department of Pathology
Department of Pathology
Department of Pathology

• Paul C. Schreckenberger, Ph.D
• Director, Clinical Microbiology Lab
• University of Illinois at Chicago
• pschreck_at_uic.edu

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The University of Illinois at Chicago Medical
Center

• Urban Medical Ctr.
• 450 Bed Teaching Hospital
• 400K Ambulatory Visits
• 43 Ancillary Departments

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Broth Culture

• RULE eliminate back-up broths except for Tissue
  and CSF with shunts -?
• References
• Morris AJ et al JCM 33161, 1995
• Derby P et al JCM 351101, 1997
• Silletti RP et al JCM 352003, 1997
• Sturgis CD et al. AJCP 108217, 1997 - CSF
• Meredith FT et al. JCM 353109, 1997 - CSF
• Dunbar SA et al. JCM 361617, 1998 - CSF

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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

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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

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Screening Sputum

• RULE perform Gram stain and evaluate under LPF
  (10 x). Reject if gt10 SEC/LPF, unless also see a
  predominant field of WBCs assoc. with single
  morphotype of bacteria

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Screening Sputum

• Cancel Culture, Charge for Gram Stain only
• DONT REQUEST REPEAT CULTURE Add Comment
  specimen contaminated with epithelial cells
  represents oropharyngeal contamination further
  processing would yield potentially misleading
  results.

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Screening Sputum

• References for using criteria of gt10 SEC to
  reject sputum1. Murray PR, Washington II JA
  Mayo Clinic Proc. 50339-344, 19752. Wong LK
  et al JCM 16627-631, 1982

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Screening Sputum

• Sputum Quality Indicator UICMC
• Using criteria of gt25 SEC/LPF
• Rejected 20 (range 8-33) - 1/91-6/92
• QA monitor 12/95 showed rejection rate of 8
• Using criteria of gt10 SEC/LPF
• Rejected 39.4 (range 32-47) - 1/96-5/97
• Current Rate 35.4 (range 29-53) - 1/99-12/99

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Number of RespiratorySpecimens Accepted for
Culture
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Screening Endotrachs

• Endotrach Quality Indicator UICMC
• Using same criteria as sputum screen (gt10 SEC)
• Reject avg. of 4.1 endotrach specimens
• For FY 98 rejected only 51 specimens
• Using criteria of gt10 SEC NOS on Gram stain
• Reject avg. of 25 of endotrach specimens
• For FY 98 would have rejected 372 specimens

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Screening Endotrachs

• RULE specimens with gt10 SEC/LPF,or no organisms
  seen on Gram stain(or yeast only) are not
  cultured
• Reference
• Morris AJ et al JCM 311027, 1993
• Zaidi AK, Reller LB JCM 34352, 1996
• Rand KH Diagn Micro Infect Dis 2755, 1997
• Gilligan PH Clin Micro Newsl 2144, 1999

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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 alJCM 5381, 1977
• Havlik D, Wood GL Lab Med 26411, 1995
• Isaac-Renton JL et al AJCP 84361, 1986
• Laird AT JAMA 52294, 1909
• McCarter YS, Robinson A AJCP 105769, 1996
• Pohl AD Keim AC Lab Med 2425, 1993

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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 52294, 1909
• McCarter YS et al AJCP 105769, 1996
• Wilson M AJCP 105665, 1996

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Correlation of PMN to AFB PositivityMcCarter and
Robinson AJCP 1996
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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)

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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

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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

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Guidelines for AFB Cultures

• Once cultures are positiveNo new specimens for
  culture accepted for 1 month after date of
  positive culture
• References for No. of Sputum Necessary
• Cascina A et al JCM 38466, 2000
• Nelson SM et al JCM 36467-469, 1998
• Divinagracia RM et al. Chest 114681-684, 1998
• Peterson EM et al JCM 373564-3568, 1999

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Distribution of first positive specimen in
patients with gt3 AFB specimensNelson S. et al.
JCM 36467, 1998
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AFB Smear Results Among 43 Patients Culture Pos
for MTBPeterson et al. JCM 373564, 1999
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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 25666, 1997
• Iseman MD, et al Clin Infect Dis 25671, 1997
• MMWR 43(suppl RR-13)1-132, 1994

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Stool Cultures

• RULE Restrict culture and OP exam to
  outpatients and inpatients admitted lt3 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 231292, 1996

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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

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Guidelines for Submitting Stool for C. difficile

• Test should only be requested when following
  criteria are met1. Antibiotic within 2 mos.
  prior to diarrhea2. Diarrhea water/profuse 6
  episodes in 36h3. Absence of other diagnosis for
  diarrhea

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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 18142, 1996

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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