Panel discussion-aidc 2017 Rapport with the microbiology lab-how it helps your patient

Transcription

1 Panel discussion-aidc 2017 Rapport with the microbiology lab-how it helps your patient Dr Ram Gopalakrishnan Dr S Nandini Moderator Dr V R Yamunadevi

2 Scenario 1 60 year old male patient admitted in ICU from ER with fever, vomiting, abdominal pain since 3 days. Patient was very restless ICU resident orders blood for culture & sensitivity Nurse withdraws 10ml of blood from peripheral vein and deposits it in the culture bottles After 48hrs no growth in blood culture bottle

3 How to interpret this result? Fundamentals of blood culture sampling How differently do you process aerobic & anaerobic culture bottles? Is it mandatory to culture 2 sets

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5 Paediatric bottles 1-3 ml each in 2 sets Aerobic alone preferable ex neonates born to mothers with prolonged ROM or other specific anaerobic infections

6 Number of blood cultures Volume of blood important. 2-3 cultures sufficient to achieve optimal blood sensitivity.

7 Scenario 2 30 year old male patient presented with C/o fever, headache with vomiting to ER. Blood culture 2 sets collected from ER grows ¼ bottle GPC No co-morbid illness Patient is clinically stable with no device in situ How to proceed??

8 Staphylococcus Coagulase positive Staphylococcus aureus Coagulase negative(less virulent) Staphylococcus epidermidis Staphylococcus haemolyticus Staphylococcus lugdunensis(except) Staphylococcus saprophyticus

9 Scenario-3 33 year old female patient presents to ER with fever since 1 week, cough, difficulty in breathing since 5days ER resident orders for 2 sets of blood culture. Instructs nurse specifically each set to be drawn one hour apart

10 What is the importance of timing of collection In which clinical condition timing plays a major role and how?

11 Important exceptions Acute endocarditis Draw 2-3 culture sets from separate sites within 30 minutes of each other and before beginning antimicrobial therapy. Begin therapy after cultures are obtained. Sub-acute endocarditis Draw 2-3 blood culture sets on day 1, spaced minutes apart. This may help to document a continuous bacteraemia.

12 4-Gram stain Importance of Gram stain /Is it mandatory? How does it help? Different samples- eg: Sputum/respiratory sample, pus/wound swab Clinicians view- Is it laboratory responsibility to share gram stain findings or clinician interest Which are the gram stains immediately reported to clinician before culture report?

13 Importance Scoring system Anaerobic growth Morphology of bacteria Specimen collection Inadequate sample

14 Bartlett score to assess quality of sputum No. of neutrophils per 10 X low power field Grade < >25 +2 No. Of epithelial cells per 10 X low power field >25-2 A final score of 0 or less indicates contamination with saliva, so repeat specimen

15 5-Alert organisms- lab & clinician perspective on preliminary tests Bacteria Fungus Parasites

16 Few examples Aseptate or septate hyphae in KOH mount of any sample Positive blood, CSF, tissues or other sterile fluid cultures Hanging drop positive S.pyogenes from throat culture Positive AFB smear MDR organisms Positive malarial parasite smear Positive sexually transmitted pathogen

17 Case scenario-6 A 28 year old female was brought to outpatient department of surgery with complaints of swelling over the left lower back since one month along with back pain and fever since 6-7 months. On local examination, swelling was noticed over the left lumbar and gluteal region, non-tender and soft in consistency. On ultrasound abdomen, a well defined cystic, thick walled lesion was noticed. On CT scan of abdomen and pelvis a well defined hypodense fluid involving the left psoas muscle was observed Pus sample was sent from OT to lab after I & D for C & S

18 Challenges faced by Microbiologist Lending / Helping hand by clinician

19 Labeling specimens Patient s name Source of specimen & Diagnosis Unique ID number Hospital number (IP/OP NO.) Ward no./unit Specimen type Date, time and place of collection Brief clinical data Name/ initials of Doctor/Nurse HIGH RISK label appropriately

20 Case scenario-7 Yeast/ gram positive budding yeast cells Site or specimen of importance Colony count for yeast in urine. Importance of speciation- why? Antifungal susceptibility- mandatory or not?

21 Case Scenario-8 21 yrs / male IIT student, hostel High grade fever for past 7 days Vague right lower quadrant pain Febrile, spleen felt

22 Which do you think will not help? CBC MP QBC Urine Routine Widal Usg abdomen Blood culture

23 Investigations CBC N 70 L29 M1 MP QBC -ve Urine Routine no pyuria Widal- positive 1 in 80 dilutions Usg abdomen splenomegaly, ileal thickening with small mesentric lymphnodes. Blood culture grew Salmonella typhi 4/4

24 Widal test: relevant or relic Based on serological response to O & H antigens Cross react with other Salmonella species Many other diseases can cause false positive Widal test Prior antibiotic exposure affects the titer Anamnestic responses can occur False negative-some patients don t mount an immune response Sensitivity and specificity only 50%

25 False positive - in typhus, acute falciparum malaria, chronic liver disease associated with raised globulin levels (auto-immune hepatitis) and disorders such as rheumatoid arthritis, myelomatosis and nephrotic syndrome. In a study of healthy blood donors performed in central India, seropositivity for typhoid fever using the S. typhi O antigen or S. typhi H antigen was observed in 8 and 14 percent, respectively

26 Spot the error A 33 year old female patient Pus culture and sensitivity E.coli Cefotaxime resistant Cefoperazone sulbactam sensitive Pipericillin tazobactam sensitive Nitrofurantoin sensitive Gentamicin resistant Meropenem sensitive

27 Only for urine isolates Cefazolin Norfloxacin Nitrofurantoin Nalidixic acid(enterobacteriaceae)

28 SPOT THE ERROR

29 Drugs active against only Gram positive organisms Gram negative Vancomycin, organisms teicoplanin Colistin Clindamycin Polymyxin B Daptomycin Linezolid Aztreonam Macrolides (ex Nalidixic acid salmonella, shigella) Penicillin Rifampicin

30 SPOT THE ERROR

31 USEFUL INDICATOR ANTIBIOTICS ORGANISM RESISTANCE TO INFERENCE/ACTION Staphylococci Oxacilllin or Cefoxitin MRSA Resistant to Beta lactam and βl and βli Sensitive Vancomycin, Daptomycin, Linezolid Staphylococci, S.pneumoniae, Beta H Streptococci Erythromycin Inducible clindamycin resistance D test should be performed Avoid clindamycin usage as patients won t respond to therapy S. Pneumoniae Oxacillin(zone<19mm) Perform MIC separately for Penicillin, Cefotaxime, Ceftriaxone, or Meropenem Enterococci Susceptible to Ampicillin Susceptible to ampi, amox, amox- clav, PT and Imipenem susceptibility to E.faecalis Enterococci High level Gentamycin High level Streptomycin It is not synergistic with cell wall active agents eg Ampicillin, Penicillin, Vancomycin( High inoculum)

32 Spot the error

33 Take home message Order tests which have good literature support Interpret with caution/obsolete Widal Know your lab and interact Culture of culture