3. Wounds, lab diagnosis of purulent infections

types of wounds?

mechanical, chemical and thermal

class 1 wounds?

uninfected

no inflammation and primarily closed

class 2 wounds?

clean-contaminated

wounds enter the respiratory, alimentary, genital or urinary tracts

enter under controlled conditions

class 3 wounds?

contaminated

fresh open

can result from insult to sterile techniques or leakage from the GIT into the wound

class 4 wounds?

dirty infected

result from improperly care of traumatic wounds

demonstrate devitalized tissue

acute wounds?

healing in less than 4 weeks

fresh wound?

occured less than 8 hrs ago

old wound?

occured over 8 hrs ago

chronic wound?

not healed after 4 weeks

signs of wound infection?

pain

edema

bad odor

inflammation

erythema

delayed wound healing

abscess formation

basic wound care step by step?

1. clean debris from wound

2. possible debridement

3. manage exudate

4. promote granulation and epithelization

5. infection management → sample collection, antimicrobials

6. minimize discomfort

what can be used to clean wounds?

saline, iodine, H2O2

sample collection basics?

1. sterile equipment always

2. avoid contamination

3. use appropriate techniques

   • wet swab before sampling dry wound

   • if the wound is large → multiple samples from different areas

   • do not only take samples of pus

how are samples taken from closed wounds?

by aspirations with a sterile needle and syringe

transport of sample?

• bacterial swab in transport medium

• aspired pus in syringe or in sterile container

• clear labels

• filled out request froms

which pathogen is suggestive of spreading infection?

S. pyogenes (group A strep)

which pathogen is suggestive of localized infection?

S. aureus (staphylococcus aureus)

which pathogen is suggestive when the pus is greenish with an aromatic smell?

Pseudomonas aeruginosa

which pathogens are suggestive when the wound has necrotic tissue and a bad smell, or has crepitation, gas in tissues and watery pus?

anaerobes

what are the next steps after sample taking?

Gram stain

Direct culture → ID + AB sensitivity

Enrichment → subculture → ID + AB sensitivity

which culture medias are typically used for direct culture?

blood agar → colony morphology, hemolysis

chocolate agar → fastidious pathogens

“gram neg” plate, like EMB

anaerobic plate

what is Hollman?

an enrichment culture

what are the general time requirements? for microscopy, direct culture, enrichment and susceptibility testing..

microscopy → few hrs

direct culture and ID → 1-3 days

• w/ susceptibility → 2-4 days

after enrichment ID → 2-4 days

• w/ susceptibilty → 3-5 days