??????????????? (the Role of Molecular Typing in Nosocomial Infection Control)

1
???????????????(the Role of Molecular Typing in
Nosocomial Infection Control)
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• accurately identifying nosocomial pathogens
• detecting unexpected antimicrobial-drug
  resistance
• epidemiologic typing

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• ??????

Pfaller MA et al. The clinical microbiology
laboratory and infection control emerging
pathogens, antimicrobial resistance, and new
technology. Clin Infect Dis 199725858-70.
4

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• ????
• ????????

• PFGE(???????)
• RAPD(????DNA???)
• REA(?????)
• ribotyping (?????)

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1????????(PFGE)
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6
??????DNA
PFGE??
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PFGE??

• ??

Enzyme

• ?520????10800kb????DNA

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• Tenover FC.et al.J Clin Microbiol,199533(9)2233
  2239

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PFGE??
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DNA
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PFGE??
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(No Transcript)
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PFGE????

• ???
• ????????????(CDC)Tenover??????????
• ????????????,????????????????????,??2-3???????????
  ,??4-6?????????,????7????????????????????????A?B?C
  ?D?????????
• ????
• ?????SPSS,????

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PFGE?????
15
PFGE??

• DNA?????,?????
• ??????????
• ???????

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2?RAPD(????DNA???)

• 1990?
• WilliamsRAPD
• WelshAP-PCR
• ?????

• ??
• ? ??? ?????,??910bp
• ????????
• ????????,2535?

17

• ESHWAR MAHENTHIRALINGAM.et al.J Clin
  Microbiol,199634(5)11291135

18

• ESHWAR MAHENTHIRALINGAM.et al.J Clin
  Microbiol,199634(5)11291135

19

• ESHWAR MAHENTHIRALINGAM.et al.J Clin
  Microbiol,199634(5)11291135

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???????????????
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Special Issue New Technology for Detecting
Multidrug-Resistant Pathogens in the Clinical
Microbiology Laboratory Lance R. Peterson and
Gary A. NoskinNorthwestern Memorial Hospital
and Northwestern University Medical School,
Chicago, Illinois, USA
EID, 2001, 7 306
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• Northwestern Memorial Hospital, Chicago
• 700-bed, university-affiliated medical center
• ??gt39,000/?
• ??56,000?/?
• ???260,000/?

23
??????????
5.79
P0.002
LR Peterson et al, EID, 2001, 7 306
24
??

• the total number of nosocomial infections per
  1,000 patient days??????????
• the number of patients with nosocomial infections
  per 100 patient discharges
  ?100???????????
• (percentage of patients with nosocomial
  infection)
• (?????????)

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??????????

• We formed a permanent, integrated infection
  control and prevention program that fully
  incorporates

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• infection control personnel,
• infectious disease personnel,
• pharmacy personnel,
• clinical microbiology personnel
• into a single working group to minimize hospital
  infections.

Hacek DM et al. Am J Clin Pathol 1999111647-54.
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??????(Methods for data collection)

• review of microbiology reports
• review of patients' medical records,
• direct observation of medical and nursing
  practice,
• active surveillance of rectal cultures of
  patients in nursing units for high-risk patients,
  
• evaluation of suspected nosocomial infections
  reported by health-care providers.

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????????????????????,??????????,????????????
??????????
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• Two interventions
• a molecular typing laboratory
• a weekly planning meeting
• infection control
• diagnostic medical microbiology (molecular
  epidemiology)
• Pharmacy
• and infectious diseases

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• ????
• ??????(?????)
• ??????????????????
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• weekly meetings
• the ongoing short- and long-term trends in
  nosocomial infections within the center
• activities of the infection control professionals
  and microbiology laboratory personnel
• any needed changes were determined.
• The organizational structure for selecting
  microbes for typing was shared by the medical
  directors of infection control and clinical
  microbiology

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?????????

• routinely genomically typedVRE
• Periodic routine typing
• fluoroquinolone-resistant P. aeruginosa,
• methicillin-resistant Staphylococcus aureus
  (MRSA),
• Enterobacter cloacae,
• Clostridium difficile
• Additional organisms for typingselected through
  surveillance of microbiology culture reports
  discussed at the weekly meeting.

• ??????VRE
• ?????
• ?????????
• MRSA
• ?????
• ????
• ????????????????????????????

????????????????,????????????????????????
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????

• REA analysis
• restriction of genomic DNA with conventional
  electrophoresis
• DNA?????

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????????
??-????(Analysis of Cost Data)

• the cost of equipment, remodeling,
• reagent and other supplies,
• salaries and benefits for three technologists,
• plus all the institutional assessments (e.g.,
  full-cost basis) required to operate a hospital
  laboratory.

• ??????????????
• ????????
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• ???????(?full-cost basis )????????

????t??
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??

• 1?VRE
• initial impetus serious nosocomial
  problem---VRE's emergence
• molecular typing results
• a pattern of numerous mini patient-to-patient
  outbreaks of distinct clones
• rather than the spread of a single persisting
  strain

• 1?VRE
• ????VRE??????
• ??????
• ???????(mini)?????
• ??????????

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??

• ???????????????
• ????????(high conality, gt90)
• ????(moderate clonality, 35-75)
• ?????(lt20 clonality).
• ?????,??????????

• genomic typing
• patient-to-patient transmission
• nosocomial outbreak
• little evidence of horizontal spread
• Using this information, we determined what
  intervention was likely to control an apparent
  outbreak (20).

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high conality, gt90 likely patient-to-patient transmission
moderate clonality, 35-75 possibly nosocomial outbreak
clonality, lt20 unlikely little evidence of horizontal spread
similarity
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• ??????,???25????????
• VRE
• ?????????
• MRSA
• ??
• ????

• During the last 2 years of this study,
• 25 possible microbial outbreaks were
  investigated by the typing laboratory
• VRE,
• fluoroquinolone-resistant P. aeruginosa,
• MRSA,
• E. cloacae,
• C. difficile.

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• Classic Spread of Nosocomial Infection
• VRE 19 strains, from 16 patients, in a 2-month
  period
• 14 strains from one of two clones (88)
• Indicating a high probability of nosocomial
  spread
• Review
• microbiology laboratory culture
  requisitions---no close contact.
• Patients existing direct connection between
  11/14 patients (14).
• infection control practices aborted the outbreak

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• VRE 19?, ??16???,2?????
• ???????????????? (88)
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• ??14???11??????
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Moderate Likelihood of Spread of Nosocomial
Infections

• ?????NI??
• 1?????,????
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• 40-60 clonality
• ??????????????????
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• During a 1-month period, in a special-care unit
• invasive infections, caused by five isolates
• Klebsiella pneumoniae,
• S. epidermidis, and
• S. hemolyticus
• DNA typing indicated 40 to 60 for each of the
  bacterial species.
• patients with genetically identical organisms
  occupied adjacent beds.
• Erecting a barrier on the unit, along with
  educating medical staff, halted the spread of
  these infections (15).

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Outbreaks not Caused by Patient-to-Patient Spread

• 2????ICU??
• 4???,64??????
• 21 clonality
• ?????????indicating unlikely patient-to-patient
  spread.
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• Suspected outbreaks consisting of four isolates
  of K. pneumonia and 64 strains of Serratia
  marcescens were investigated in the ICUs of two
  hospitals. Both investigations showed 21
  clonality, indicating unlikely patient-to-patient
  spread.
• Investigation suggested suboptimal handling of
  ventilator equipment, and both outbreaks were
  stopped by retraining of personnel using this
  equipment

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• Pseudooutbreaks
• Possible outbreaks occurred in the special-care
  nursery units of two hospitals, each of which had
  its own molecular typing section.
• seven S. aureus strains, and the other of four
  isolates of gram-negative bacilli.
• immediately typed and no (20) clonality existed.
• No interventions were instituted, and the
  apparent outbreaks were determined to be normal
  variation in infections (15,21).
• avoided culture-based surveillance investigation
  of staff by the state department of health, and
  the other avoided closing the unit for a 30-day
  full disinfection and cleaning (done in previous
  suspected outbreaks).

• 2???,??????,???????????????
• 7???
• ??????rapid typing
• no (20) clonality
• ??????
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• ????30?,?????

• 4?G-?

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P0.000006
LR Peterson et al, EID, 2001, 7 306
41
??????????
5.79
P0.002
LR Peterson et al, EID, 2001, 7 306
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• nosocomial infection 3.3-2.6 (national rate
  4.4-5)
• gt1,400 fewer patients acquired infections during
  this time,
• averting more than 50 expected deaths
• Even with endemic VRE, most of our outbreaks
  involve three or fewer patients (19).

• ????3.3???2.6(???????4.4-5)
• ??gt1,400?????
• ?????gt50
• VRE????????????

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??

• The mean number of patients with nosocomial
  infections decreased by 283 per year, a reduction
  of more than 1,100 inpatient days.
• The costs avoided by using this calculation
  averaged more than 2,150,000/year, based on 1999
  dollars.

• ?????????????? 283,????????1100?
• ?????????????2,150,000(?1999???)

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• Representatives now meet together for 45 minutes
  each week
• For Microbiology, opening the typing laboratory
  totaled 180,050. By the fifth year, costs in the
  laboratory section were stable.
• The cost for the laboratory, includng three
  medical technologists, is 400,000 yearly.
• Virtually all these costs are borne by the
  hospital.

• ????????????,45min,??
• ?????????????(?????)????180,050.
• ???????????400,000
• ????

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• While such a grant program would cost up to 2
  billion each year if all U.S. hospitals
  participated,
• the projected reduction in cost of treating
  nosocomial infections could reach over five times
  that amount.
• a savings of 5.00 for each dollar spent.

• ????????
• ????????????20???
• ?????????????????5?(100?)!
• ???1????5??

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• Typing time within 1 week
• 48 hours.
• Lack of clonality suggests other reasons for the
  apparent outbreak,
• antimicrobial-agent use pressure,
• failure of appropriate nursing-care practices,
• or simply random variation in the number of
  infections.
• Early knowledge of whether microbial clonality is
  present or absent focuses the scope of an
  investigation and facilitates appropriate
  intervention.

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• cost of rapid detection using the polymerase
  chain reaction (PCR)
• one day of glove isolation
• could be completed in a single 8-hour workday.
• As gene chip technology moves into clinical use,
  detecting a large number of resistance
  determinants soon after a patient is admitted to
  the hospital should be possible.

• PCR ??
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• technically possible
• medically useful
• economically justified

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50
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• ???? 04?05?
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• ????????(PFGE)??
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Thank You