Transcript Gilligan Bio Lecture

Best though and continuous study
Jerome Groopman
Peter Gilligan
Professor, Pathology-Lab Medicine
UNC School of Medicine
4/10/2015
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How I became a clinical microbiologist
• Obtained doctoral degree in microbiology at the University
of Kansas
• Did post-doctoral training (2 years) in medical and public
health microbiology at UNC Hospitals
• Director of Microbiology Labs at St Christopher’s Hospital
for Children (Philadelphia) for 4 years
• Past 25+ years, Associate Director then Director of the
Clinical Microbiology-Immunology Labs at UNC Hospitals
4/10/2015
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What do clinical microbiologists do?
• We serve:
» our patients
» our health care-providing colleagues, physicians,
nurses, physician assistants, pharmacy colleagues
» hospital administrators
• We make money for the institution
» general public by insuring the public health
• Involved in studying outbreaks of several emerging
infectious diseases including current fungal meningitis
one
• will tell you about an emerging pathogens todayClostridium difficile
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How do we serve?
• central role in the diagnosis and management of
infectious diseases
• central role in infection prevention and antimicrobial
use
• recognize emerging disease threats and outbreaks
including bioterrorism events
• we educate & train health care providers
• we create new knowledge (research) to deal with
practical problems
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Best things about my job
• Direct impact on patient care and public health of the
community
• Intellectually challenging job requiring a broad fund of
knowledge-need to know a little about a lot of things –I am
never bored!!!!!!!
• Get to work with cutting edge technology
• Work with highly motivated and intelligent individuals
• Get to be at the cutting edge of infectious disease
diagnosis
• I am involved in global issues as they relate to infectious
diseases
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Worst things about my job
• Incredible amounts of governmental oversight
• Increasing emphasis on financial aspects of the job
• Declining talent pool of technologists-THIS A GREAT JOB
MARKET FOR YOU WITH APPROPRIATE TRAINING
• Too much travel
• Need to be responsible for an organization that run
24/7/365-we never close. Personally have worked through
ice storms, blizzards, and hurricanes.
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How you can become a clinical
microbiologist
• CLS programs available here, ECU, WSSU, Wake Forest,
UNC-CH
» Education is also available on line
• 2 more years of school to get a BS in CLS
» There is no unemployment in this group
• Take ASCP certification exam to become certified as a
MT.
» Starting salary is 41,000 and up
» Career options are amazingly diverse; many former UNC
students work in leadership positions in the pharmaceutical
and biotech industries- Also have 5 former employees
4/10/2015
currently in Med, Grad, Pharmacy School
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Emerging Infectious Diseases in the Past 30 Years
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Clostridium difficile*#
novel H1N1 influenza AHIV*#
SARS and MERS CoV*
Cryptosporidium*
E. coli O157:H7*#
Nipah virus
nv Creutzfeldt-Jakob disease
Sin Nombre Virus
West Nile Virus
Vibrio vulnificus*
Cyclospora
Bacillus anthracis #(BT agent)
CA-ORSA*#
TSST-1 S. aureus*#
XDR- and MDR-TB*
MDR- pneumococcus*#
MDR-Acinetobacter*
Rapidly growing mycobacterium*#
Campylobacter*#
ESBL-Enterobactericeae*
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Rotavirus*
Norovirus*
BK virus*
Chlamydophila pneumoniae
Penicillium marneffei
Legionella*
Burkholderia cepacia complex*#
Burkholderia gladioli*#
VRE*#/VRSA
Helicobacter pylori*
HHV-6*
HPV*
HCV*
Avian influenza (H5N1)
Ehrlichia chaffenesis*
Borrelia burgdorferi* (Lyme disease)
Enterotoxigenic E. coli#
Enteroadherent E. coli*
Bordetella avium
Microsporidium*
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Clostridium difficile
• General
characteristics
» Gram positive rod
» Spore former
» Anaerobic
» Can be part of human
microflora
» Pathogenicity due to
the production of two
protein exotoxins A and
B
Chance favors only the prepared
mind
Louis Pasteur
Key events in the discovery of C.
difficile
• Larson and colleagues describe a toxin in the
feces of a child with pseudomembranous colitis
(1977)
• Bartlett and colleagues show that C difficile can
induce colitis in hamsters given clindamycin and
then a variety of antibiotics and then proves that
the organism can cause the same disease in
humans (1978)
» Serendipity is important- showed that C. sordellii
antitoxin could neutralize toxins produced by C. difficile
in a tissue culture cytotoxicity assay.
Key events in the discovery of C.
difficile
• Among others, Gilligan
and colleagues show
that C. difficile is the
most common bacterial
agent in a general
population (1980)
• Lyerly and colleagues
purify two toxins, A and
B, from C. difficile and
also produce an
important anti-toxin
against these
organisms (1982)
US deaths due to C.
difficle has increased
2.3X since 2000 ;
mortality 4%
Peery et al, 2012
Gastroenterology (in press)
Nature Reviews Gastroenterology &
Hepatology 8, 17-26 (January 2011)
Top Ten Pathogens Causing
Healthcare Associated Infections, 2011
300
Number of Pathogens
250
200
150
100
50
0
What makes C difficile an important pathogen in the
industrialized world?
• Important ideas
» Organism can survive in the environment for months as
spores; spores are refractory to disinfectants especially
alcohol and all antimicrobials
» Alternation in the gut flora is important in predisposing
patient’s to disease with this organism- antibiotics mediate
this change
• Microbiome is less diverse
» Most common diarrheal disease etiology in the industrialized
world requiring specific antimicrobial interventions
Age related C. difficile incidence in
US
What factors has resulted in the reemergence of Clostridium difficile??
• Better case ascertainment
» Improvement in lab diagnosis
• Aging population
» Decline in Bifidobacterium with age, an organism
important in colonization resistance, in gut flora may
create more permissive environment for C. difficile
• Increased use of antimicrobials especially
fluoroquinolones with anti-anaerobic activity to
which C. difficile is resistant
» This is being debated in the infectious disease
community
» 90% of C. difficile isolates are fluoroquinolone resistant
What factors has resulted in the reemergence of Clostridium difficile?
• Increased contamination of health care setting with C.
difficile spores making infections more likely
» Cleanliness of British Public Health Service hospitals has
become a major political issue there
• Shared rooms and bathroom facilities
» Particular issue in Canada and Britain
Pathogenesis of C. difficile
• Key steps in pathogenesis
» Anaerobic gut flora confers “colonization resistance” to
the host from infection with C. difficile
» Alteration of this gut flora by antimicrobial therapy
creates a permissive environment for the vegetation of
C. difficile spores
» Spores are either present in gut at time of alteration of
gut flora or are obtained from the hospital environment
during the period of gut flora alteration
• May take as long as six weeks for gut flora to return to normal
• Antimicrobials most impacting gut flora include clindamycin,
cephalosporins, and perhaps newer fluoroquinolones
Pathogenesis of C. difficile
• Organism grows and begins to produce both toxin A & B
» Toxins have high degree of sequence similarity
• Toxins bind to specific receptors on surface of the cell and
enter cell via receptor mediated endocytosis
• Toxins acts as a glucosyltransferase inactivating small
GTPase
Pathogenesis of C. difficile
• GTPase control a variety of cell functions resulting in:
- actin condensation which leads to cell rounding, membrane
blebbing, apoptosis, and cell death
» increased permeability of the colonic epithelium
» chemokine expression which increases inflammatory
response
» increases neutrophil infiltration
» loss of tight junctions resulting in neutrophil migration into
the intestine
Clostridium difficile PMC and toxic
megacolon
C. difficile: Spectrum of disease
Asymptomatic carriage
Mild diarrhea
Profuse diarrhea with non-specific colitis
Pseudomembranous colitis
Toxic megacolon
frequency
Rules for C. difficile testing
• If the stick stands, the
test is banned (type 15)
» High carriage rate in
patients on antimicrobials
• If the stick falls, test
them all. (type 6 + 7)
Dr. Stephen Brecher
4/10/2015
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Report as positive for
C. difficile
Report as negative for
C. difficile
Based on data in literature
of PVP >95% for CDI
If NAAT for C. difficile toxin gene is positive, report as positive for C. difficile.
If NAAT for C. difficile toxin gene is negative, report as negative as C. difficile
UK algorithms
GDH/NAAT negative-report as CDI unlikely
GDH/NAAT positive; toxin positive- CDI likely
GDH/NAAT positive; toxin negative- C. difficile present; C.
difficile excretor
Rationale is GDH/NAAT positive; toxin positive-worse
outcome- CTN test superior to toxin EIA
Applying the UK algorithm
• Using our data and a three step algorithm
• 87.6% are GDH/PCR negative- no CDI
• 7.9% are PCR pos/toxin negative- C. difficile excretor
• 4.4% GDH/toxin positive-CDI
What does “C. difficile execretor”
mean?
Likely be a clinical decision with infection
prevention ramifications
Bottom line: Need to treat the patient not the
laboratory test
Infection Rate (Number of Infections Per
1000 Patient Days)
0.9
UNC Healthcare-associated infection rates:
C. difficile
0.8
0.7
0.6
0.5
0.4
0.3
0.2
Switched to GDH/PCR
algorithm
0.1
0
2003
2004
2005
2006
2007 2008
Year
2009
2010
2011
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Changing deaths in UK due to C. difficile
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Treatment of C. difficile disease
• Initial studies showed that metronidazole and vancomycin
had similar initial response to therapy (90%) and similar
disease recurrence rates (5 to 12%)
• Metronidazole became the drug of choice because it was
much cheaper and because of concerns of vancomycin
use resulting in increased rates of VRE and concerns
about the emergence of VRSA
• Fidaxomicin is a new drug that is used to mainly
recurrence of C. difficile infection
Treatment of C. difficile disease
• Two studies (published 6/05) showed much
higher rates of treatment failures/recurrences than
previously reported with metronidazole
» One study (CID 40:1586, 2005) only 50% of patients
were cured, 22% had symptoms continuous for > 10
days and 28% had recurrences
» In a Canadian survey (Pepin et al. CID 40:1591-7),
recurrence rates increased from 21% in 1991-2002 to
48% in 2003-2004; in those over 65 y.o., that rate was
close to 60% in 2003-4
The problem of recurrence of C. difficile
disease
• Molecular epidemiology studies have shown that
recurrences of C. difficile can be:
» due to relapse- a second or third episode of C. difficile due
to the patients own organism or
» re-infection obtaining a new strain from the patient’s
environment. (each occurs in approximately 50% of
patients)
» Failure to develop colonization resistance and mount an
immune response thought to play a crucial role in
recurrences
The problem of recurrence of C.
difficile disease
» fecal microbiota transplant
• Donor stool from healthy family member
• re-populate gut via colonoscopy (75%) or naso-gastric tube
(25%)
• 91% efficacy based on data from over 300 patients
• Done at UNC
» Use of probiotics such as lactobacilli or Saccharomyces
has not been particularly impressive to date in repopulating the gut to prevent recurrences
Final thought:
In patients with C. difficile disease,
remember to wash your hands with
soap and water; not alcohol gels