MICROBIOLOGICAL EPIDEMIOLOGY OF RESPIRATORY ISOLATES IN ICU PATIENTS

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MICROBIOLOGICAL EPIDEMIOLOGY OF RESPIRATORY
SPECIMENS IN ICU PATIENTS
Dr Farooq Cheema, Dr Waseem Tariq, Dr Raja
Ishtiaq, Dr Tabassum Qureshi, Dr Vincent Ioos,
Dr Rubina Aman.
Medical ICU, Pakistan Intsitute of Medical
Sciences, Islamabad
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VENTILATOR ASSOCIATED PNEUMONIA

• Ventilator Associated Pneumonia (VAP) is defined
  as a bacterial nosocomial pneumonia occurring
  more than 48 hours after endotracheal intubation
  in patients placed on mechanical ventilation.
• VAP is the most prevalent infection in ICU
  patients, accounting for up to 46 of nosocomial
  infections1.
• VAP causes a significant increase in mortality,
  morbidity and length of stay amongst ICU
  patients.
• Early institution of empirical antibiotic therapy
  with appropriate drugs leads to a decrease in the
  mortality attributable to VAP.
• 1. Vincent JL, Bihari DJ, Suter PM, et al.
  Prevalence of Nosocomial Infections in ICUs in
  Europe. Results of the European Prevalence of
  Infection in Intensive Care (EPIC) Study, JAMA
  1995, 274639-644.

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ORGANISMS RESPONSIBLE FOR VAP

• The major pathogens responsible for causing VAP
  are Gram Negative Bacteria and Staph. Aureus.
• However, there is often a big difference in the
  causative organisms for VAP even from one
  hospital to another due to the varying
  microbiological environment.
• There is also a dearth of data regarding the
  microbiological epidemiology of VAP in developing
  countries.

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VAP PATHOGENS IN DEVELOPING COUNTRIES
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VAP PATHOGENS IN DEVELOPED COUNTRIES
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AIMS AND OBJECTIVES

• Description of the epidemiology of the pathogens
  found in the tracheal secretions of mechanically
  ventilated patients in the Medical ICU at PIMS.
• Basis for editing recommendations for the
  empirical treatment of VAP in our institution
• Improving outcome
• Decreasing emergence of resistant bugs

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STUDY DESIGN

• This is a retrospective analysis of data
  collected from the PIMS Laboratory Management
  Information System (LMIS).
• We analyzed the results of tracheal secretions
  c-s study done for patients admitted in the
  Medical ICU and placed on mechanical ventilation
  from 01/01/2007 to 31/12/2007.
• Data regarding the severity of illness, mortality
  and length of mechanical ventilation was
  collected from an Excel file maintained
  prospectively in the ICU.

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MATERIALS AND METHODS

• A total of 182 samples from 96 patients were
  retrieved, in which 242 bacteria were cultured.
  24 samples showed no growth, 1 sample showed a
  mixed growth.
• Bacteria which were cultured twice from the same
  patient within 7 days were excluded from the
  analysis to prevent duplication of results.
• Tracheal Secretions C-S studies are usually done
  in the ICU only if there is a clinical suspicion
  of an infection e.g. fever, new infiltrates on a
  chest x-ray, worsening ABGs, elevated WBC counts,
  new onset of purulent secretions.

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POPULATION STUDIED

• Pop 96 patients (2007 MICU 358 with 77 on MV)
• Mean age 38 years (2007 MICU 39)
• Sex ratio (M/W) 1,52 (2007 MICU 1,8)
• 81 medical, 19 surgical (2007 MICU 74 M)
• Mean SAPS3 63 (2007 MICU 65)
• Expected mortality 41,8
• Observed mortality 44,5
• SMR1,06 (2007 MICU 1,18)
• Mean length of stay 17 days
• (2007 MICU 9 days)
• Mean length of mechanical ventilation 13 days
• (2007 MICU 7 days)

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RESULTS
Bacteria Cultured Percentage Percentage
Pseudomonas Pseudomonas Pseudomonas 56 28.3
Klebsiella pneumoniae Klebsiella pneumoniae Klebsiella pneumoniae 41 20.71
Escherichia coli Escherichia coli Escherichia coli 20 10.1
Proteus Proteus Proteus 26 13.1
Citrobacter spp. Citrobacter spp. Citrobacter spp. 1 0.51
Serratia liquefaciens Serratia liquefaciens Serratia liquefaciens 1 0.51
Acinetobacter Acinetobacter Acinetobacter 32 16.2
Staph. Aureus (MSSA) Staph. Aureus (MSSA) Staph. Aureus (MSSA) 7 3.53
Staph. Aureus (MRSA) Staph. Aureus (MRSA) Staph. Aureus (MRSA) 13 6.55
Coagulase neg. Staph. Coagulase neg. Staph. Coagulase neg. Staph. 1 0.51
198 100
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RESULTS
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PSEUDOMONASSENSITIVITY TO ANTI-PSEUDOMONAL
PENICILLINS
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PSEUDOMONAS SENSITIVITY TO CEPHALOSPORINS
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PSEUDOMONASSENSITIVITY TO QUINOLONES
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PSEUDOMONASSENSITIVITY AMINOGLYCOSIDES
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PSEUDOMONASSENSITIVITY TO CARBAPENAMS
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ENTEROBACTERIACEAESENSITIVITY TO PENICILLINS
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ENTEROBACTERIACEAE SENSITIVITY TO CEPHALOSPORINS
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ENTEROBACTERIACEAE SENSITIVITY TO QUINOLONES
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ENTEROBACTERIACEAE SENSITIVITY TO
AMINOGLYCOSIDES
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ENTEROBACTERIACEAESENSITIVITY TO CARBAPENAMS
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ACINETOBACTER SENSITIVITY TO PENICILLINS
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ACINETOBACTERSENSITIVITY TO CEPHALOSPORINS
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ACINETOBACTERSENSITIVITY TO QUINOLONES
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ACINETOBACTERSENSITIVITY TO AMINOGLYCOSIDES
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ACINETOBACTERSENSITIVITY TO CARBAPENAMS
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MRSASENSITIVITY TO VARIOUS ANTIBIOTICS
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LIMITATIONS

• Retrospective analysis, colonization versus
  infection not assessed.
• Low specificity of tracheal secretions C-S in the
  diagnosis of VAP.
• Lack of standardization of the culture and
  sensitivity study.

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DISCUSSION

• Epidemiology of respiratory specimen is dominated
  by gram negative bacteria and pseudomonas as the
  first pathogen
• High incidence of the resistance to ceftazidime,
  imipenem, amynoglycoside and quinolones
• Low incidence of staphylococcus aureus isolates
  and among them one third are methicillin
  sensitive

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CONCLUSION

• Recommendations for empirical treatment of VAP in
  our MICU should target pseudomonas
• (piperacillin tazobactam or cefoperazone
  sulbactam)
• (amikacine or tobramycine)
• MRSA should be considered only when the patient
  is very severe or is known to be colonized by
  MRSA
• Prospective surveillance of VAP
• on the basis of internationally recognized
  definition
• correlated with the number of days of mechanical
  ventilation
• To calculate an incidence
• Interventions to reduce VAP

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THANK YOU!
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ENTEROBACTERIACEAESENSITIVITY TO PENICILLINS
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ENTEROBACTERIACEAE SENSITIVITY TO CEPHALOSPORINS
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ENTEROBACTERIACEAE SENSITIVITY TO QUINOLONES
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ENTEROBACTERIACEAE SENSITIVITY TO
AMINOGLYCOSIDES
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ENTEROBACTERIACEAESENSITIVITY TO CARBAPENAMS