Categorías: Todo - pathogens - morphology - culture - testing

por Annie John hace 5 años

389

Sputum culture

In microbiological diagnostics, the approach to identifying pathogens in sputum cultures involves several critical steps. Initially, the source type is considered as it influences the battery of tests performed.

Sputum culture

Sputum culture

7. Reporting

ALWAYS date/time/initial reports, beginning of overnight tests, susceptibility testing, etc.
Final report
Date/time/initial
Note relevant biochemical/susceptibility testing
Report pathogen ID/contaminant/normal flora
Quantitate growth

Other

Quantitate qualitatively (i.e. many, few, etc.)

Urine/BAL

Quantitate numerically (i.e. >100,000 CFU/ml)

Interim report
Run & record any more tests performed (biochemical/susceptibility testing)
Record if there is any additional growth
Preliminary report
Potential pathogen isolated

Report relevant info (i.e. LF GNR) or use abbreviated ID & quantitate

Pathogen ID known or antibiotic susceptibilities known = report as is & do not perform susceptibility testing (i.e. beta hemolytic strep is known to be susceptible to penicillin)

Pathogen ID unknown or pathogen antibiotic susceptibilities unknown = report as antibiotic susceptibility/ID pending

Normal flora/contaminant isolated

Report as normal flora/possible contaminant & quantitate

Unable to isolate colonies/subculture/perform gram stain/get colonies to grow

Report as culture ID pending

6. For every phase of testing, determine if additional testing is needed

Pathogen
Continue testing
Contaminant
Discontinue testing

2. Look at different colony types

Multiple colony types
Mixture of normal flora & pathogens
Pathogens
Normal flora

4. Perform gram stain

GNC
GNDC
GNR
GNCB
GPR

7. Use abbreviated ID if possible

1. First & foremost = always consider source type

May change battery of tests performed

5. Correlate colony morphology with gram stain results

GNR/GNCB (growth with only fastidious organisms)

Perform gram stain

GNCB with school of fish/railroad tracks

Consider other organisms

Suspect Haem ducreyi

Perform XV tests on horse BAP

X & XV growth

Haem ducreyi

Consider other organisms/repeat testing

Perform XV tests on horse BAP

V & XV growth

Haem parainfluenzae

Haem parahaemolyticus

X growth

Haem species

XV growth

Haem influenzae

Haem haemolyticus

GNR/GNCB (growth on BAP, CHOC, & MAC)
Growth on MAC

Growth on BAP

Perform oxidase

NLF

Observe swarming on BAP

Probable Acinetobacter species (if ADH/ODC -, plump GNCB, colorless/pink colonies on MAC)

Streno maltophilia (if ADH/ODC -, strong maltose oxidizer, pale yellow/lavendar colonies on BAP)

Perform spot indole

Ampicillin R

ODC -

Prot penneri

ODC +

Ampicillin S

Prot mirabilis

Prot vulgaris

(Non-sterile body source, LF) observe lactose fermentation

(GI site) perform GNR ID panel

(Non-GI site) perform spot indole

Perform GNR ID panel

Esch coli

(Sterile body source, LF) perform GNR ID panel

G

Glucose asaccharolytic

Glucose oxidizer

ADH

LDC

Probable Elizabeth meningoseptica (if ODC -, indole +, yellow pigment)

Perform polymyxim B susceptibility

Burk cepacia complex (if ODC variable, pale yellow colonies)

Additional test results needed for definitive ID

Growth @ 42 C

Additional results needed for definitive ID

Pseudo aeruginosa (if green/red/brown pigment, LDC -, ODC - , nitrate +)

Glucose fermenter

Correlate with key biochemical reactions

GPC
Perform catalase

Possible streptococci

Gamma

Non-hemolytic strep

Alpha

Perform optochin

Strep viridans

Strep pneumoniae

Beta

Perform PYR

Perform hippurate hydrolysis

Perform bile esculin

Beta strep, not A, B, or D, or Enterococcus species

Perform 6.5% NaCl

Group D strep

Enterococcus species

Group B strep

Perform bacitracin

Group A strep

+

Perform coagulase

-

Perform bacitracin or modified oxidase

Baccitracin R/modified oxidase -

(Urine) novobiocin

R

Probable staph saprophyticus

S

Coag neg staph

(Other) coag neg staph

Bacitracin S/modified oxidase +

Micrococcus species

Staph aureus

3. Examine colony morphology

Wide variety of colony morphologies
GNR/GNCB
Gray/tan/bluish-gray/white, small, translucent, raised, convex, smooth, hockey puck
Think possible GNDC
Gray, smooth, pinpoint, flat/raised, alpha, translucent
Think possible GPC in chains
White/gray, smooth, raised, beta or gamma, opaque
Think possible GPC in clusters or chains