VENTILATOR ASSOCIATED
PNEUMONIAS
current perceptions
Dr.T.V.Rao MD

Professor Department of Microbiology Sri Deva Raj Urs ...
Pneumonia
Still the “Old man’s friend?”
• Bacterial, Viral,
Chemical, Aspiration,
Nosocomial,
Community Acquired,
“Walking...
Pneumonia can be a life threatening
condition
Is Something Serious ?

• Hospital-acquired
pneumonia (HAP)
and ventilatoras...
Ventilator associated pneumonia
• Ventilator associated pneumonia (VAP) is
defined as nosocomial pneumonia occurring
in a ...
Early concepts
• As early as 1972, studies have shown that the
airway of mechanically ventilated patients
quickly becomes ...
Ventilator Associated Pneumonia (VAP)
- Key Points • VAP is the 2nd most common nosocomial infection =
15% of all hospital...
Centres for Disease and Control
• The diagnosis of
pneumonia in
mechanically ventilated
patients is difficult, and
still t...
Challenge and Controversy
• The diagnosis and
management of VAP
remains one of the
most

controversial
and challenging
top...
Who are prone -High Risk Patients
• For Sepsis
–
–
–
–
–

Post op / post procedure / post trauma
Post splenectomy (encapsu...
Nosocomial infection are
Multidrug Resistant
• Many patients with HAP,
VAP, and HCAP are at
increased risk for
colonizatio...
Aspiration
• Aspiration of colonized
pathogenic

microorganisms on the
oropharynx and
gastrointestinal tract is
the main r...
Variation of Incidence Rate
• In different studies, the incidence of VAP was
reported different, depending on the
definiti...
Aero digestive ,upper airway + upper
digestive tract contribute pathogens
• The primary route of
VAP pathogenesis is a
com...
When does VAP occur?
• Cook et al showed . . .
– 40.1% developed before day 5
– 41.2% developed between days 6 and 10
– 11...
Time frame of intubation and risk
• Risk of pneumonia at
intubation days
– 3.3% per day at day 5
– 2.3% per day at day
10
...
PAHOGENESIS
– The pathogenesis of
ventilator-associated
pneumonia usually
requires that two
important processes
take place...
Mechanical device also
contributes the events

doctortvrao@gmail.com

17
Etiology
• Bacteria cause
most cases of HAP,
VAP, and HCAP
and many
infections are
polymicrobial;
rates are especially
hig...
Causative Organisms
• Early onset:
–
–
–
–
–

Haemophilus influenza
Streptococcus pneumoniae
Staphylococcus aureus (methic...
Summary of pathogens responsible for VAP in a study of 420 patients.

Hunter J D Postgrad Med J 2006;82:172-178

doctortvr...
Drug resistance a concern in Ventilator
Associated Pneumonias
• A. baumanni was the
most common emerging
isolated pathogen...
Other Isolates in Ventilator associated
Pneumonias
– Pseudomonas aeruginosa.
• the most common MDR gram-negative bacterial...
Acinetobacter species
– Acinetobacter species

• More than 85% of
isolates are
susceptible to
carbapenems, but
resistance ...
Newer Carbapenemases
• As of June 2010, there
were three reported
cases of
Enterobacteriaceae
isolates bearing this
newly ...
Staphylococcus aureus and
Streptococcus pneumoniae
– Methicillin-resistant Staphylococcus aureus
• vancomycin-intermediate...
L. Pneumophila and environment
• Rates of L. pneumophila
vary considerably
between hospitals and
disease occurs more
commo...
Influenza too can cause VAP
• Nosocomial virus and fungal
infections are uncommon
causes of HAP and VAP in
immunocompetent...
Fungal pathogens can cause
VAP
–Fungal
pathogens.
•Aspergillus
species
•Candida
albicans
doctortvrao@gmail.com

29
Pathogenesis – Entry of Pathogens
• Where do the bacteria come from?
– Tracheal colonization- via oropharyngeal
colonizati...
Oropharyngeal colonization can be
source of VAP
• Scannapieco et al showed a transition in the
colonization of dental plaq...
Gastrointestinal colonization
• Increased gastric pH leads to bacterial
overgrowth
• Reflux can then lead to colonization ...
Viral Pathogens
• Outbreaks of HAP, VAP, and
HCAP due to viruses, such
as influenza, parainfluenza,
adenovirus, measles, a...
Bio films
• Many species, including
Pseudomonas aeruginosa
and Staphylococcus
aureus, produce bio films,
which surround th...
Bio films,
• The surviving
organisms may
play a role in
relapses by
shedding infective
particles from the
endotracheal tub...
Multidrug resistant organisms are
associated with …
• The prevalence of MDR
pathogens varies by patient
population, hospit...
Diagnosis?
• A pulmonogist with
25+ years
experience guesses
he is only correct
60% of the time
when diagnosing
pneumonia ...
Diagnosis is imprecise and usually
based on a Combination of
–Clinical factors - fever or hypothermia;
change in secretion...
Strategies in Diagnosis in VAP are
multifaceted

• Clinical
Strategy
• Bacteriologic
Strategy
• Comparing
Diagnostic
Strat...
Diagnostic practices
• VAP
– Invasive versus non-invasive techniques
– BAL/PBB versus tracheal aspirate
– Quantitative ver...
Specimen collection for Optimal Results
• Distal airway samples may be obtained by
using bronchoscopic or nonbronchoscopic...
Bacteriologic Strategy
• Quantitative cultures can
be performed on
endotracheal aspirates or
samples collected either
bron...
Nonquantitative or
semiquantitative airway sampling.
• Gram staining and nonquantitative and
semiquantitative cultures of ...
Specimen collection
• Tracheobronchial secretions were collected by
the pulmonologist , following specimen
collection guid...
Qualitative cultures X Qualitative cultures
• Qualitative cultures were considered positive
when the growth of any micro-o...
Culture positivity true or false?
• Qualitative cultures were considered positive
when the growth of any micro-organism
oc...
Which is optimal sample ?
• Despite numerous publications on the subject,
controversy still exists on the optimal method
o...
Differentiates between pathogenic
from non pathogenic ?
• Analysing samples using quantitative culture
techniques theoreti...
WHY IS THERE NO GOLD STANDARD?
• After more than 10 years of trying multiple
invasive and non-invasive diagnostic
techniqu...
Good Microbiology practices reduces
Antibiotic usage
• Invasive tests such as bronchoscope BAL or
protected specimen brush...
Precautions in collecting and
transporting
• After proper hand washing and wearing sterile
gloves before suctioning, the e...
Gram stain is highly

sensitive

Sputum or tracheal suction gram stain
NO ORGANISMS
in non-neutropenic pts.

NO HAP/VAP 94...
Gram staining of secretions are
useful in early decisions
• The upper respiratory tract
of patients is colonized with
pote...
Bacterial culture of tracheal
secretion
•
•

•

Qualitative culture
- non specific
Semi-quantitative
culture
- low specifi...
Collection of bronchial Secretions
• Distal airway samples may be obtained by
using bronchoscopic or nonbronchoscopic
tech...
Bronchoscopic BAL
• Bronchoscopic BAL has
been in use since 1988
(See Figure 1); however,
the BAL technique is still
not c...
Collection of bronchial Secretions
• Distal airway samples may be obtained by
using bronchoscopic or nonbronchoscopic
tech...
• The sensitivity of quantitative BAL is 42 to 93% with a
mean of 73%. Specificity is 45 to
• 100% with a mean of 82%. Spe...
Bacterial culture of tracheal
secretion
•
•
•

Qualitative culture
- non specific
Semi-quantitative culture
- low specific...
Protected Specimen Brush
ProBAL© PSB by Mill-Rose
• The protected specimen brush
technique for the diagnosis of
pneumonia ...
Semiquantitative
1+ : rare
<10 colonies/plate
2+: few
10-102 colonies/plate
3+: moderate >102-3 colonies/plate
4+: numerou...
Collection of bronchial Secretions
• Distal airway samples may be obtained by
using bronchoscopic or nonbronchoscopic
tech...
Qualitative and quantitative
• Qualitative endotracheal aspirates are easy to
obtain but have a high false-positive rate i...
Differing opinions in specimen collection
• Recent studies have consistently shown that
outcome in VAP may not be influenc...
Severely ill patients need
• In selected groups of severely ill
patients, quantitative cultures of
tracheal aspirates shou...
Which methods of collection is
better
• Two diagnostic strategies for ventilatorassociated pneumonia — bronchoalveolar
lav...
False negative – False Positive Results
• Investigators reported
that the clinical diagnosis
of VAP is associated 30–
35% ...
Other Supporting Bacterial Cultures
• Bacteraemia and positive pleural effusion
cultures are generally considered to be ab...
Multiresistant pathogens in Ventilator
associated pneumonias
• The incidence of
multiresistant
pathogens is also
closely l...
Uncommon microbes are often
missed
• Legionella species , anaerobes
fungi viruses, and even
Pneumocystis carinii should be...
Immunological methods in
Diagnosis
• A recently described immunological method
for the diagnosis of VAP holds great promis...
Newer Methods in Diagnosis
• Gibot and colleagues prospectively studied 148
mechanically ventilated patients with suspecte...
How much a clinician needs from
Microbiology
• Culture results are currently used to guide
adjustment or withdrawal of ant...
Evidence-based early and
appropriate therapy in VAP
Mortality

Inappropriate

Mortality

Appropriate

Mortality

Early

Mo...
Benchmarking prescribing practice
• Triggers to starting antibiotics
– Regular sampling versus clinician guided
– Timing i...
Best option in choosing Antibiotics
• Considerations in making selection
–
–
–
–

Setting (community, NH, hospital)
Suspec...
Continuous Removal of Subglottic
Secretions


Use an ET tube
with continuous
suction through
a dorsal lumen
above the cuf...
No uniformity in treatment schedules
• However, despite these
advances, the majority
of issues related to the
management o...
Clinical diagnosis of ventilator-associated
pneumonia
What is not controversial?
• Clinical criteria for the diagnosis of ...
Handwashing
What role does handwashing play in
nosocomial pneumonias?
The greatest role

doctortvrao@gmail.com

80
VAP Prevention
• Wash hands before
and after
suctioning,
touching ventilator
equipment, and/or
coming into
contact with
re...
Epidemiological data differs from
situations
• The incidence of
multiresistant
pathogens is also
closely linked to local
f...
Can we deliver a successful
Treatment
• Successful treatment of patients with VAP
remains a difficult and complex undertak...
Supporting Evidences
• Consequently, most
experts recommend that
two sets of blood cultures
and a thoracentesis for
nonloc...
Handwashing
• Hand washing is the single most
important (and easiest!!!) method for
reducing the transmission of pathogens...
Oral Care
• Dental plaque contains multiple pathogens
(may include s. aureus and p. aeruginosa)
• After 48 hours, normal o...
Probiotics in VAP
• Probiotics prophylaxis of
VAP using Lactobacillus
rhamnosus GG appears safe
and efficacious in a selec...
Patient examination in the Intensive
Care Unit

• MORE IS
MISSED BY
NOT LOOKING
• THAN BY NOT
KNOWING
doctortvrao@gmail.co...
Interdisciplinary rivalry increases
Mortality
• VAP is an excellent
example of a problem
that can best be solved
by interd...
"Million Lives Campaign”
• "Million Lives Campaign" and included use of
a ventilator bundle of interventions,
developed an...
Medical Profession is Changing from
Confidence to Confusion ?

doctortvrao@gmail.com

91
References
•
•
•
•
•
•
•
•

•
•

American Thoracic Society. HAP in adults: diagnosis, assessment of severity, initial anti...
Presented as Guest Lecture at Indian
Association of Medical Microbiologists
(IAMM)- KC held at M.S. Ramaiah Medical
Colleg...
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  1. 1. VENTILATOR ASSOCIATED PNEUMONIAS current perceptions Dr.T.V.Rao MD Professor Department of Microbiology Sri Deva Raj Urs Medical College, Tamaka, Kolar , India Tamaka Kolar doctortvrao@gmail.com 1
  2. 2. Pneumonia Still the “Old man’s friend?” • Bacterial, Viral, Chemical, Aspiration, Nosocomial, Community Acquired, “Walking,” Bronchopneumonia, Necrotizing, Ventilator associated doctortvrao@gmail.com 2
  3. 3. Pneumonia can be a life threatening condition Is Something Serious ? • Hospital-acquired pneumonia (HAP) and ventilatorassociated pneumonia (VAP), is an important cause of morbidity and mortality in hospitalized patients. doctortvrao@gmail.com 3
  4. 4. Ventilator associated pneumonia • Ventilator associated pneumonia (VAP) is defined as nosocomial pneumonia occurring in a patient after 48 hours of mechanical ventilation via a tracheal or tracheostomy tube. It is commonly classified as either early onset (occurring within 96 hours of start of mechanical ventilation) or late onset (>96 hours after start of mechanical ventilation) doctortvrao@gmail.com 4
  5. 5. Early concepts • As early as 1972, studies have shown that the airway of mechanically ventilated patients quickly becomes colonized with gram-negative organisms. In the past, it was thought that pathogens came from the ventilator equipment in use. However, as the problem was studied and evidence accumulated, it became evident that the origin of the VAP was from a source other than the ventilator equipment. doctortvrao@gmail.com 5
  6. 6. Ventilator Associated Pneumonia (VAP) - Key Points • VAP is the 2nd most common nosocomial infection = 15% of all hospital acquired infections • Incidence = 9% to 70% of patients on ventilators • Increased ICU stay by several days • Increased avg. hospital stay 1 to 3 weeks • Mortality = 13% to 55% • Added costs of $40,000 - $50,000 per stay Centers for Disease Control and Prevention, 2003. Rumbak, M. J. (2000). Strategies for prevention and treatment. Journal of Respiratory Disease, 21 (5), p. 321; doctortvrao@gmail.com 6
  7. 7. Centres for Disease and Control • The diagnosis of pneumonia in mechanically ventilated patients is difficult, and still there is no "goldstandard" diagnostic method. It is usually based on the combination of clinical, radiological, and microbiological criteria defined by Centres for Disease and Control (CDC) doctortvrao@gmail.com 7
  8. 8. Challenge and Controversy • The diagnosis and management of VAP remains one of the most controversial and challenging topics in management of critically ill patients.” doctortvrao@gmail.com 8
  9. 9. Who are prone -High Risk Patients • For Sepsis – – – – – Post op / post procedure / post trauma Post splenectomy (encapsulated organisms) Cancer Transplant / immune supressed Alcoholic / Malnourished • For Dying – – – – Genetic predisposition (e.g. meningococcus) Delayed appropriate antibiotics Yeasts and Enterococcus Site • For Both – Cultural or religious impediment to treatment doctortvrao@gmail.com 9
  10. 10. Nosocomial infection are Multidrug Resistant • Many patients with HAP, VAP, and HCAP are at increased risk for colonization and infection with MDR pathogens • HAP and VAP are a frequent cause of nosocomial infection that is associated with a higher crude mortality than other hospital-acquired infections doctortvrao@gmail.com 10
  11. 11. Aspiration • Aspiration of colonized pathogenic microorganisms on the oropharynx and gastrointestinal tract is the main route for the development of VAP. On the other hand, the major risk factor for VAP is intubation and the duration of mechanical ventilation doctortvrao@gmail.com 11
  12. 12. Variation of Incidence Rate • In different studies, the incidence of VAP was reported different, depending on the definition, the type of hospital or ICU, the population studied, and the type of rate calculated and varies from 7% to 70% In a large database, 1-day point prevalence study, conducted in 1417 European ICUs, pneumonia accounted for 47% of nosocomial infections doctortvrao@gmail.com 12
  13. 13. Aero digestive ,upper airway + upper digestive tract contribute pathogens • The primary route of VAP pathogenesis is a combination of two processes: bacterial colonization of the aero digestive (upper airway + upper digestive) tract and the subsequent aspiration into the lower airway. doctortvrao@gmail.com 13
  14. 14. When does VAP occur? • Cook et al showed . . . – 40.1% developed before day 5 – 41.2% developed between days 6 and 10 – 11.3% developed between days 11-15 – 2.8% developed between days 16 and 20 – 4.5% developed after day 21 Cook et al. Incidence of and risk factors for ventilator-associated pneumonia in critically ill patients. doctortvrao@gmail.com 14
  15. 15. Time frame of intubation and risk • Risk of pneumonia at intubation days – 3.3% per day at day 5 – 2.3% per day at day 10 – 1.3% per day at day 15 . doctortvrao@gmail.com 15
  16. 16. PAHOGENESIS – The pathogenesis of ventilator-associated pneumonia usually requires that two important processes take place: • Bacterial colonization of the aero digestive tract • The aspiration of contaminated secretions into the lower airway. doctortvrao@gmail.com 16
  17. 17. Mechanical device also contributes the events doctortvrao@gmail.com 17
  18. 18. Etiology • Bacteria cause most cases of HAP, VAP, and HCAP and many infections are polymicrobial; rates are especially high in patients with ARDS doctortvrao@gmail.com 18
  19. 19. Causative Organisms • Early onset: – – – – – Haemophilus influenza Streptococcus pneumoniae Staphylococcus aureus (methicillin sensitive) Escherichia coli Klebseilla • Late onset: – Pseudomonas aeruginosa – Acinetobacter – Staphylococcus aureus (methicillin resistant) • Most strains responsible for early onset VAP are antibiotic sensitive. Those responsible for late onset VAP are usually multiple antibiotic resistant Am J Resp Crit Care (1995) doctortvrao@gmail.com 19
  20. 20. Summary of pathogens responsible for VAP in a study of 420 patients. Hunter J D Postgrad Med J 2006;82:172-178 doctortvrao@gmail.com ©2006 by The Fellowship of Postgraduate Medicine 20
  21. 21. Drug resistance a concern in Ventilator Associated Pneumonias • A. baumanni was the most common emerging isolated pathogen many of them were multidrugresistant (MDR) or pan drug-resistant (PDR). The other common isolated pathogens were K. pneumoniae, P. aeruginosa and methicillin-resistant S. aureus (MRSA). doctortvrao@gmail.com 21
  22. 22. Other Isolates in Ventilator associated Pneumonias – Pseudomonas aeruginosa. • the most common MDR gram-negative bacterial pathogen causing HAP/VAP, has intrinsic resistance to many antimicrobial agents – Klebsiella, Enterobacter, and Serratia species. • Klebsiella species – intrinsically resistant to ampicillin and other aminopenicillins and can acquire resistance to cephalosporins and aztreonam by the production of extended-spectrum –lactamases (ESBLs) – However ESBL-producing strains remain susceptible to carbapenems ? • Enterobacter species • Citrobacter and Serratia species doctortvrao@gmail.com 22
  23. 23. Acinetobacter species – Acinetobacter species • More than 85% of isolates are susceptible to carbapenems, but resistance is increasing , Most recent concern. • Stenotrophomonas maltophilia, and Burkholderia cepacia: – resistant to carbapenems ? doctortvrao@gmail.com 23
  24. 24. Newer Carbapenemases • As of June 2010, there were three reported cases of Enterobacteriaceae isolates bearing this newly described resistance mechanism in the US, the CDC stated that "All three U.S. isolates were from patients who received recent medical care in India."
  25. 25. Staphylococcus aureus and Streptococcus pneumoniae – Methicillin-resistant Staphylococcus aureus • vancomycin-intermediate S. aureus – sensitive to linezolid – linezolid resistance has emerged in S. aureus, but is currently rare ? – Streptococcus pneumoniae and Haemophilus influenzae. • sensitive to vancomycin or linezolid, and most remain sensitive to broadspectrum quinolones doctortvrao@gmail.com 26
  26. 26. L. Pneumophila and environment • Rates of L. pneumophila vary considerably between hospitals and disease occurs more commonly with serogroup 1 when the water supply is colonized or there is ongoing construction doctortvrao@gmail.com 27
  27. 27. Influenza too can cause VAP • Nosocomial virus and fungal infections are uncommon causes of HAP and VAP in immunocompetent patients. Outbreaks of influenza have occurred sporadically and risk of infection can be substantially reduced with widespread effective infection control, vaccination, and use of anti influenza agents doctortvrao@gmail.com 28
  28. 28. Fungal pathogens can cause VAP –Fungal pathogens. •Aspergillus species •Candida albicans doctortvrao@gmail.com 29
  29. 29. Pathogenesis – Entry of Pathogens • Where do the bacteria come from? – Tracheal colonization- via oropharyngeal colonization or GI colonization – Ventilator system • How do they get into the lung? – Breakdown of normal host defenses – Two main routes • Through the tube • Around the tube- microaspiration around ETT cuff doctortvrao@gmail.com 30
  30. 30. Oropharyngeal colonization can be source of VAP • Scannapieco et al showed a transition in the colonization of dental plaques in patients in the ICU • Control=25 subjects presenting to preventive dentistry clinic • Study group=34 noncardiac patients admitted to medical ICU at VA hospital (sampled within 12 hours of admission and every third day) doctortvrao@gmail.com 31
  31. 31. Gastrointestinal colonization • Increased gastric pH leads to bacterial overgrowth • Reflux can then lead to colonization of oropharynx • Use of antacids and H2 blockers associated with GI colonization Safdar et al. The pathogenesis of ventilator-associated pneumonia: its relevance to developing effective strategies for prevention doctortvrao@gmail.com 32
  32. 32. Viral Pathogens • Outbreaks of HAP, VAP, and HCAP due to viruses, such as influenza, parainfluenza, adenovirus, measles, and respiratory Syncytial virus have been reported and are usually seasonal. • Influenza, pararinfluenza, adenovirus, and respiratory Syncytial virus account for 70% of the nosocomial viral cases of HAP,VAP, and HCAP doctortvrao@gmail.com 33
  33. 33. Bio films • Many species, including Pseudomonas aeruginosa and Staphylococcus aureus, produce bio films, which surround the organisms when attached to endotracheal tubes, and make them relatively resistant to the actions of antibiotics and host defences. doctortvrao@gmail.com 34
  34. 34. Bio films, • The surviving organisms may play a role in relapses by shedding infective particles from the endotracheal tube into the lower respiratory trac doctortvrao@gmail.com 35
  35. 35. Multidrug resistant organisms are associated with … • The prevalence of MDR pathogens varies by patient population, hospital, and type of ICU, which underscores the need for local surveillance data • MDR pathogens are more commonly isolated from patients with severe, chronic underlying disease, those with risk factors for HCAP, and patients with late-onset HAP or VAP doctortvrao@gmail.com 36
  36. 36. Diagnosis? • A pulmonogist with 25+ years experience guesses he is only correct 60% of the time when diagnosing pneumonia before seeing the CXR. A little better than a coin-toss. doctortvrao@gmail.com 37
  37. 37. Diagnosis is imprecise and usually based on a Combination of –Clinical factors - fever or hypothermia; change in secretions; cough; apnea/ bradycardia; tachypnea –Microbiological factors - positive cultures of blood/sputum/tracheal aspirate/pleural fluids –CXR factors - new or changing infiltrates doctortvrao@gmail.com 38
  38. 38. Strategies in Diagnosis in VAP are multifaceted • Clinical Strategy • Bacteriologic Strategy • Comparing Diagnostic Strategy doctortvrao@gmail.com 39
  39. 39. Diagnostic practices • VAP – Invasive versus non-invasive techniques – BAL/PBB versus tracheal aspirate – Quantitative versus non-quantitative methods • Infection definitions – Clinician decision or standardised definitions doctortvrao@gmail.com 40
  40. 40. Specimen collection for Optimal Results • Distal airway samples may be obtained by using bronchoscopic or nonbronchoscopic techniques. With nonbronchoscopic techniques, a catheter is blindly advanced through the endotracheal tube or tracheostomy and wedged in the distal airway. Various sampling methods include blind bronchial suction (BBS), blind BAL, and blind PSB sampling. doctortvrao@gmail.com 41
  41. 41. Bacteriologic Strategy • Quantitative cultures can be performed on endotracheal aspirates or samples collected either bronchoscopically or nonbronchoscopically, and each technique has its own diagnostic threshold and methodologic limitations. The choice of method depends on local expertise, experience, availability, and cost doctortvrao@gmail.com 42
  42. 42. Nonquantitative or semiquantitative airway sampling. • Gram staining and nonquantitative and semiquantitative cultures of tracheal secretions have the advantages of reproducibility and of requiring little technical expertise and no specialized equipment or technique. However, these studies add little to the sensitivity and specificity of the clinical diagnosis of VAP, as the upper respiratory tract is rapidly, within hours of intubation, colonized by potential pulmonary pathogens, even when pneumonia is not present doctortvrao@gmail.com 43
  43. 43. Specimen collection • Tracheobronchial secretions were collected by the pulmonologist , following specimen collection guidelines, after tracheal instillation of 5 ml saline. The specimens were sent to the laboratory and cultivated within 1 hour of collection. A dilution of the tracheal aspirate was prepared and inoculated with a calibrated loop on chocolate agar and MacConkey agar doctortvrao@gmail.com 44
  44. 44. Qualitative cultures X Qualitative cultures • Qualitative cultures were considered positive when the growth of any micro-organism occurred, and quantitative cultures were considered positive when the growth of 105 colony-forming units (cfu)/ml or more was observed. doctortvrao@gmail.com 45
  45. 45. Culture positivity true or false? • Qualitative cultures were considered positive when the growth of any micro-organism occurred and quantitative cultures were considered positive when the growth of 105 colony-forming units (cfu)/ml or more was observed. cultures from tracheal aspirates were calculated according to standard formulae doctortvrao@gmail.com 46
  46. 46. Which is optimal sample ? • Despite numerous publications on the subject, controversy still exists on the optimal method of microbiological diagnosis of VAP,As the trachea and tracheal tube rapidly become colonised with bacteria in the critically ill patient, cultures of sputum or tracheal aspirates may simply yield colonising organism doctortvrao@gmail.com 47
  47. 47. Differentiates between pathogenic from non pathogenic ? • Analysing samples using quantitative culture techniques theoretically permits differentiation between oropharyngeal organisms present at low concentrations and the higher concentrations of pathogenic organisms. doctortvrao@gmail.com 48
  48. 48. WHY IS THERE NO GOLD STANDARD? • After more than 10 years of trying multiple invasive and non-invasive diagnostic techniques, the procedure which is specific, sensitive, rapid and inexpensive is yet to be developed. No studies have shown the superiority of any specific diagnostic method currently in use, thus, medical community still has no gold standard for the diagnosis of VAP doctortvrao@gmail.com 49
  49. 49. Good Microbiology practices reduces Antibiotic usage • Invasive tests such as bronchoscope BAL or protected specimen brush (PSB) may avoid the extended use of antibiotics for clinically insignificant organisms, but no direct consensus or evidence suggests that one test is superior to the other; all have their advantages and disadvantages. doctortvrao@gmail.com 50
  50. 50. Precautions in collecting and transporting • After proper hand washing and wearing sterile gloves before suctioning, the endotracheal secretions were collected by instilling 1-2 ml of sterile normal saline into the endotracheal tube and then collecting it back with the help of sterile mucous trap. The specimen collected was immediately transported to the laboratory within one hour of collection. doctortvrao@gmail.com 51
  51. 51. Gram stain is highly sensitive Sputum or tracheal suction gram stain NO ORGANISMS in non-neutropenic pts. NO HAP/VAP 94% doctortvrao@gmail.com 52
  52. 52. Gram staining of secretions are useful in early decisions • The upper respiratory tract of patients is colonized with potential pulmonary pathogens a few hours after intubation. A positive Gram's stain may guide the initial antibiotic therapy. However prior antibiotic and corticosteroid therapy can reduce the sensitivity of this technique doctortvrao@gmail.com 53
  53. 53. Bacterial culture of tracheal secretion • • • Qualitative culture - non specific Semi-quantitative culture - low specificity Quantitative culture : TS, BAL, PSB - increase specificity doctortvrao@gmail.com 54
  54. 54. Collection of bronchial Secretions • Distal airway samples may be obtained by using bronchoscopic or nonbronchoscopic techniques. With nonbronchoscopic techniques, a catheter is blindly advanced through the endotracheal tube or tracheostomy and wedged in the distal airway. Various sampling methods include blind bronchial suction (BBS), blind BAL, and blind PSB sampling. doctortvrao@gmail.com 55
  55. 55. Bronchoscopic BAL • Bronchoscopic BAL has been in use since 1988 (See Figure 1); however, the BAL technique is still not completely standardized. The amount of liquid instilled into the lung for specimen retrieval varies from 130 to 150 ml, with the first sample being discarded. doctortvrao@gmail.com 56
  56. 56. Collection of bronchial Secretions • Distal airway samples may be obtained by using bronchoscopic or nonbronchoscopic techniques. With nonbronchoscopic techniques, a catheter is blindly advanced through the endotracheal tube or tracheostomy and wedged in the distal airway. Various sampling methods include blind bronchial suction (BBS), blind BAL, and blind PSB sampling. doctortvrao@gmail.com 57
  57. 57. • The sensitivity of quantitative BAL is 42 to 93% with a mean of 73%. Specificity is 45 to • 100% with a mean of 82%. Specific affected area of the lung can be visualized and sampled • • More accurate than sputum or tracheal aspirates • • May enable physician to identify non-infectious lesions • • Detects intracellular organisms in BAL cultures quickly and specifically • with highly positive predictive value doctortvrao@gmail.com 58
  58. 58. Bacterial culture of tracheal secretion • • • Qualitative culture - non specific Semi-quantitative culture - low specificity Quantitative culture : TS, BAL, PSB - increase specificity doctortvrao@gmail.com 59
  59. 59. Protected Specimen Brush ProBAL© PSB by Mill-Rose • The protected specimen brush technique for the diagnosis of pneumonia has been used for 20 years. This bronchoscopic technique use a sample collection brush (protected by a sheath) inside the scope channel until the suspect portion of the lower airway has been reached. The brush is then extended into the desired specimen and withdrawn. This technique was first described in 1979 by Wimberly, et al. doctortvrao@gmail.com 60
  60. 60. Semiquantitative 1+ : rare <10 colonies/plate 2+: few 10-102 colonies/plate 3+: moderate >102-3 colonies/plate 4+: numerous >103-4 colonies/plate 5+: numerous >104 colonies/plate doctortvrao@gmail.com 61
  61. 61. Collection of bronchial Secretions • Distal airway samples may be obtained by using bronchoscopic or nonbronchoscopic techniques. With nonbronchoscopic techniques, a catheter is blindly advanced through the endotracheal tube or tracheostomy and wedged in the distal airway. Various sampling methods include blind bronchial suction (BBS), blind BAL, and blind PSB sampling. doctortvrao@gmail.com 62
  62. 62. Qualitative and quantitative • Qualitative endotracheal aspirates are easy to obtain but have a high false-positive rate in ICU patients because of airway colonization. When quantitative endotracheal-aspirate cultures are used, a cutoff value of 106 is the most accurate, with a sensitivity of 38-82% and a specificity of 72-85% doctortvrao@gmail.com 63
  63. 63. Differing opinions in specimen collection • Recent studies have consistently shown that outcome in VAP may not be influenced by whether cultures are obtained by bronchoscope or from tracheal aspirates collected at the bedside. Furthermore, a cost effectiveness analysis strongly supported the employment of tracheal aspirates in the management of VAP. • Ruiz M, Torres A, Ewig S, Marcos MA, Alcón A, Lledó R, Asejo MA,Maldonado M: Noninvasive versus invasive microbial investigation in ventilator associated pneumonia: evaluation of outcome. Am J Respir Crit Care Med 2000, 162:119-125. doctortvrao@gmail.com 64
  64. 64. Severely ill patients need • In selected groups of severely ill patients, quantitative cultures of tracheal aspirates should not replace qualitative cultures for confirmation of diagnosis or management of antibiotic therapy. • Ventilator associated pneumonia: comparison betweenquantitative and qualitative cultures of tracheal aspirates Luis Fernando Aranha Camargo1, Fernando Vinícius De Marco2, Carmen Sílvia Valente Barbas1, Cristiane Hoelz1, Marco Aurélio Scarpinella Bueno1, Milton Rodrigues Jr1, Verônica Moreira Amado1, Raquel Caserta3, Marinês Dalla Valle Martino4, Jacyr Pasternak4 and Elias Knobel5 doctortvrao@gmail.com 65
  65. 65. Which methods of collection is better • Two diagnostic strategies for ventilatorassociated pneumonia — bronchoalveolar lavage with quantitative culture of the bronchoalveolar-lavage fluid and endotracheal aspiration with nonquantitative culture of the aspirate — are associated with similar clinical outcomes and similar overall use of antibiotics • A Randomized Trial of Diagnostic Techniques for Ventilator-Associated Pneumonia N Engl J Med 2006; 355:2619-2630December 21, 2006 doctortvrao@gmail.com 66
  66. 66. False negative – False Positive Results • Investigators reported that the clinical diagnosis of VAP is associated 30– 35% false-negative and 20–25% false-positive results . And also, ICU patients do not always have systemic signs of infection due to their underlying disease (chronic renal failure) doctortvrao@gmail.com 67
  67. 67. Other Supporting Bacterial Cultures • Bacteraemia and positive pleural effusion cultures are generally considered to be able to identify the organisms causing the pneumonia, if no other source of infection is found. Therefore, most experts recommend that investigation of suspected VAP should include taking two sets of blood samples for culture and tapping pleural > 10 ml, even though spread to the blood or pleural space occurs in < 10% of VAP doctortvrao@gmail.com 68
  68. 68. Multiresistant pathogens in Ventilator associated pneumonias • The incidence of multiresistant pathogens is also closely linked to local factors and varies widely from one institution to another. Consequently, each ICU must continuously collect meticulous epidemiologic data doctortvrao@gmail.com 69
  69. 69. Uncommon microbes are often missed • Legionella species , anaerobes fungi viruses, and even Pneumocystis carinii should be mentioned as potential causative agents but are not considered to be common in the context of pneumonia acquired during MV. However, several of these causative agents may be more common and potentially underreported because of difficulties involved with the diagnostic doctortvrao@gmail.com 70
  70. 70. Immunological methods in Diagnosis • A recently described immunological method for the diagnosis of VAP holds great promise for the future. The triggering receptor expressed on myeloid cells (TREM-1) is a member of the immunoglobulin super family, and is involved in the acute inflammatory response. Neutrophils express high levels of TREM-1 on exposure to infected tissues. doctortvrao@gmail.com 71
  71. 71. Newer Methods in Diagnosis • Gibot and colleagues prospectively studied 148 mechanically ventilated patients with suspected VAP. A rapid immunoblot technique was used to measure soluble triggering receptor expressed on myeloid cells TREM-1 in bronchoalveolar lavage fluid. They showed that the presence of soluble TREM-1 in the bronchoalveolar lavage (BAL) fluid was a highly accurate method for the diagnosis of fungal or bacterial pneumonia with a sensitivity of 98% and a specificity of 90%. doctortvrao@gmail.com 72
  72. 72. How much a clinician needs from Microbiology • Culture results are currently used to guide adjustment or withdrawal of antibiotic therapy rather than to decide whether to treat or not. The practice of changing therapy with culture results has resulted in reduced consumption of antibiotics. • Conversely, studies have shown that overtreatment with antibiotics may select organisms such as Pseudomonas aeruginosaand Acinetobacter calcoaceticus doctortvrao@gmail.com 73
  73. 73. Evidence-based early and appropriate therapy in VAP Mortality Inappropriate Mortality Appropriate Mortality Early Mortality doctortvrao@gmail.com 74
  74. 74. Benchmarking prescribing practice • Triggers to starting antibiotics – Regular sampling versus clinician guided – Timing in relation to investigation • Choice of antibiotic regimen – Early empiric broad-spectrum cover versus narrow spectrum with escalation • De-escalation practice • Duration of prescription doctortvrao@gmail.com 75
  75. 75. Best option in choosing Antibiotics • Considerations in making selection – – – – Setting (community, NH, hospital) Suspected organism (GNRs, GPCs) Host factors (immunosuppression) Local susceptibility patterns • Initial empiric and broad; subsequent narrowing –Concept is to not miss the organism with initial coverage and then deescalate when able to do it. doctortvrao@gmail.com 76
  76. 76. Continuous Removal of Subglottic Secretions  Use an ET tube with continuous suction through a dorsal lumen above the cuff to prevent drainage accumulation doctortvrao@gmail.com 77
  77. 77. No uniformity in treatment schedules • However, despite these advances, the majority of issues related to the management of VAP remain unresolved and are subject to controversy. This is particularly true for the diagnostic evaluation of the patient with suspected VAP. doctortvrao@gmail.com 78
  78. 78. Clinical diagnosis of ventilator-associated pneumonia What is not controversial? • Clinical criteria for the diagnosis of VAP have a limited diagnostic accuracy. • This is true for single criteria such as infiltrates in chest radiograph, fever or hypothermia, leukocytosis or leucopoenia, and increase in the amount and/or purulence of tracheobronchial secretions, as well as for diagnostic rules incorporating some of these criteria. doctortvrao@gmail.com 79
  79. 79. Handwashing What role does handwashing play in nosocomial pneumonias? The greatest role doctortvrao@gmail.com 80
  80. 80. VAP Prevention • Wash hands before and after suctioning, touching ventilator equipment, and/or coming into contact with respiratory secretions. doctortvrao@gmail.com 81
  81. 81. Epidemiological data differs from situations • The incidence of multiresistant pathogens is also closely linked to local factors and varies widely from one institution to another. Consequently, each ICU must continuously collect meticulous epidemiologic data doctortvrao@gmail.com 82
  82. 82. Can we deliver a successful Treatment • Successful treatment of patients with VAP remains a difficult and complex undertaking. Despite broad clinical experience with this disease, no consensus has been reached concerning issues as basic as the optimal antimicrobial regimen or its duration. In fact, to date, evaluation of various antimicrobial strategies for the treatment of bacterial VAP has been difficult for several reasons. doctortvrao@gmail.com 83
  83. 83. Supporting Evidences • Consequently, most experts recommend that two sets of blood cultures and a thoracentesis for nonloculated pleural effusions of ≥10 mm in diameter on a lateral decubitus chest radiograph should be part of the evaluation of suspected VAP doctortvrao@gmail.com 84
  84. 84. Handwashing • Hand washing is the single most important (and easiest!!!) method for reducing the transmission of pathogens. • Use of waterless antiseptic preparations is also acceptable and may increase compliance. doctortvrao@gmail.com 85
  85. 85. Oral Care • Dental plaque contains multiple pathogens (may include s. aureus and p. aeruginosa) • After 48 hours, normal oral flora of critically ill pts changes to more virulent gram (-) organisms • Aspiration of oral secretions around the cuff and ETT occurs in all vented patients • VAP rates are reduced when oral care measures are included in a comprehensive prevention program doctortvrao@gmail.com 86
  86. 86. Probiotics in VAP • Probiotics prophylaxis of VAP using Lactobacillus rhamnosus GG appears safe and efficacious in a select population with a very high risk of VAP, "Ultimately, probiotics may fulfil a role in antimicrobial stewardship programs given the reductions in antibiotic consumption. • American Journal of Respiratory and Critical Care Medicine. doctortvrao@gmail.com 87
  87. 87. Patient examination in the Intensive Care Unit • MORE IS MISSED BY NOT LOOKING • THAN BY NOT KNOWING doctortvrao@gmail.com 88
  88. 88. Interdisciplinary rivalry increases Mortality • VAP is an excellent example of a problem that can best be solved by interdisciplinary cooperation rather than interdisciplinary rivalry and devaluing the contributions of selected members of the health care team. doctortvrao@gmail.com 89
  89. 89. "Million Lives Campaign” • "Million Lives Campaign" and included use of a ventilator bundle of interventions, developed and implemented the Institute for Healthcare Improvement (IHI IHI Institute for Healthcare Improvement (Boston, MA, USA) ..... (http://www.ihi.org/IHI/Topics/ doctortvrao@gmail.com 90
  90. 90. Medical Profession is Changing from Confidence to Confusion ? doctortvrao@gmail.com 91
  91. 91. References • • • • • • • • • • American Thoracic Society. HAP in adults: diagnosis, assessment of severity, initial antimicrobial therapy and preventive strategies. Am J Resp Crit Care 1995;153: 1711-1725. Chastre J. et al. Ventilator Assosciated Pneumonia. Am J Respir Crit Care Med 2002; 10:364-368. Cutler C> et al. Improving oral care in patients receiving mechanical ventilation. Am J Crit Care 2005; 14(5): 389-394. Grap M. et al. Preventing VAP: evidence-based care 2004; 16: 349-458. Keenan S. et al. VAP: prevention, diagnosis, and therapy. Crit Care Clin 2002; 18(1): 107-125. Kollef M. Prevention of hospital associated and ventilator associated pneumonia. Crit Care Med 2002; 32: 1396-1405. Marik, P. et al. One good turn deserves another. Crit Care Med 2002; 30(9): 2146-2148. Anesthesiology: Pneumatikos, Ioannis A. M.D., Ph.D., F.C.C.P.; Dragoumanis, Christos K. M.D., Ph.D.; Bouros, Demosthenes E. M.D., Ph.D., F.C.C.P. March 2009 - Volume 110 - Issue 3 - pp 673-680 Centers for Disease Control and Prevention, 2003. Rumbak, M. J. (2000). Strategies for prevention and treatment. Journal of Respiratory Disease, 21 (5), p. 321; Anesthesiology: Pneumatikos, Ioannis A. M.D., Ph.D., F.C.C.P.; Dragoumanis, Christos K. M.D., Ph.D.; Bouros, Demosthenes E. M.D., Ph.D., F.C.C.P.vMarch 2009 - Volume 110 - Issue 3 - pp 673-680 Ventilator associated pneumoniaJ D Hunter Correspondence to:
 Dr J D Hunter
 Department of Anaesthetics and Intensive Care, Macclesfield District General Hospital, Victoria Road, Macclesfield SK10 3BL, UK; john.hunter@echeshire-tr.nwest.nhs.uk doctortvrao@gmail.com 92
  92. 92. Presented as Guest Lecture at Indian Association of Medical Microbiologists (IAMM)- KC held at M.S. Ramaiah Medical College, Bangalore India on 4th Sept 2010 email doctortvrao@gmail.com doctortvrao@gmail.com 93
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