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How and in which time frame should Campylobacter and Cl.difficile be transported? (feces)
- Anaerobic transport system (Port a cul)
within 2h or stored at 2-8°C for 24h
How do you collect urine for examination?
1. Morning mid stream (first wash genitals, let the first few ml pass, collect sample) - 20-30ml
2. Suprapubic bladder aspiration (insert needle through skin into bladder -> if no urination possible)
3. Urinary bladder catherization
-> determines localization of infection:
bladder infection = first urine after catherization is sterile
kidney inflammation = microorganisms in all urine
What are the cultivation methods/agars used in case of feces examination? What step can be done to obtain glucose/lactose properties?
- Nutrient broth: to cultivate Salmonella (continue with MacConkey)
- MacConkey, Levin Agar, EMB: Salmonella, Shigella -> colourless colonies
- Bisulfite agar: Salmonella (grows in black colonies that are coloured by the reaction of ferrous of the agar with the H2S of the Salmonella)
-Kligers Iron agar: to determine the glucose/lactose fermentation properties of the bacterium (initially red, turns yellow in case of fermentation - slant->lactose, bottom -> glucose; in case of H2S turns black)
What are the identification methods in case of feces examination?
1. Microscopy (gram staining to find agent)
(methylene blue stain in case of many Leukocytes: indicates invasive, non toxinemic infection)
2. Biochemical properties
-> API (chambers filled with different enzymes)
-> VITEK2 (automated determination of bio. properties)
3. Seroidentification (we give known antibody onto slide and mix it with specimen: in case of anitgen present = Agglutination)
-> Agglutination on glass
-> Latex agglutination
4. Bacterial susceptibility to antibiotics
-> Disk diffusion test (disks with antibiotics given onto agar with colonies -> if resistant nothing happens, if not resistant: clear circle around disc)
->E-test (determination of lowest possible concentration to fight microbes)
->VITEK2 (automated system to determine susceptibility to antibiotics)
How and in which time frame should Salmonella, Shigella and pathogenic E.coli be transported? (feces)
- in a sterile container (simple transport container or Cary blair transport) within 2h or stored at 2-8*C for 24h
- can also be inserted in simple transport media
What are the possible agents in case of infected wounds/pus formation?
- Lung, brain, abdominal abcess
-> anaerobic: B. fragilis
-> Gr+ cocci: S.aureus, S. pyogenes
- Traumatic open wounds;
->Cl.perfringens, Cl. tetani
- Surgical wounds:
-> S. aureus
- Cat and dog bites:
-> Pasteurella multocida
- Human bites:
-> oral microbiota
- can be mono-, association and anaerobic microrganisms
How are causative agents of urine cultured? What tests are added for detection of specific characteristics?
Culture at 37°C for 24-48h on:
-Blood agar (S. saprophyticus)
-MacConkey (E.coli -> turn from red to pink because of pH change)
Additionally:
- Kligers Iron agar: to determine the glucose/lactose fermentation properties of the bacterium (initially red, turns yellow in case of fermentation - slant->lactose, bottom -> glucose)
- Motility test in semiliquid media
How is urine transported and what is Quantitative testing?
- Transported in simple transport container or urotube in 2h (better in 1h)
- Can be stored at 4°C for 18h
Quantative testing:
- Microscopic: 1ml urine
if 75-95% of vision field is filled with bacteria: 10^5/ml
if 50% of vision field is filled with bacteria: 10^4/ml
- Bacteriologic examination (urotube)
1ml urine
->10^5/ml of one species = positive, causative agent found
->10^5/ml of various species= not trustworthy, repeat
->10^4/ml of one species = not trustworthy, repeat
->10^4/ml of various species= negative
In case of clinical manifestations 10^2 can be considered serious indicator
What are the possible causative agents for urinary tract infections?
E.coli and S. saprophyticus
often:
Enterobacter
Proteus mirabilis
Enterococus faecalis
less often:
S. aureus
S. epidermidis
S. pyogenes
Mycoplasma
What are the identification methods in case of urine examination?
1. Microscopy (gram staining to find agent)
2. Biochemical properties
-> API (chambers filled with different enzymes)
-> VITEK2 (automated determination of bio. properties)
3. Seroidentification (we give known antibody onto slide and mix it with specimen: in case of anitgen present = Agglutination)
-> Agglutination on glass
-> Latex agglutination
4. Bacterial susceptibility to antibiotics
-> Disk diffusion test (disks with antibiotics given onto agar with colonies -> if resistant nothing happens, if not resistant: clear circle around disc)
->E-test (determination of lowest possible concentration to fight microbes)
->VITEK2 (automated system to determine susceptibility to antibiotics)
What can be less possible (other) causative agents for feces examination?
Microorganisms: Staphylococcus, Klebsiella, Proteus, Bac. cereus, Pseudomonas
Viruses: Rota-, Adeno-, ECHO-, Koksaki
What are the most possible causative agents in case of feces examination?
Most common: Salmonella, Shigella, Campylobacter
Less common: Pathogenic E.coli, Cl. difficile
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