Final Practical Answers – Flashcards
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| Environments for blood cultures |
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| aerobic and anaerobic |
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| Why don't you put blood cultures in fridge? |
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| fastidious organisms may be present |
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| Incubation and temperature for blood cultures |
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| 37oC blood culture incubator for 5 days |
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| How does the incubator know if there is bacteria? |
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| The incubator detects any metabolic activity in the bottle by changes in O2 or CO2 concentration |
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| False positives in blood cultures |
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| respiration of white blood cells that are in high number in the culture |
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| What happens when a blood culture bottle is positive? |
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| . A needle is aseptically inserted into the bottle and blood is extracted to be gram stained and subbed onto blood, chocolate & Macconkey agar. |
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| What to plates to add if GPC or GNR are seen in blood culture? |
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| a selective plate (CNA or PEA) is added |
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| What do selective plates in blood cultures allow for? |
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| isolation of the gram positive organism in the event that the gram negative rod is a swarming Proteus sp |
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| What if GPC in pairs and chains are seen in a blood culture? |
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| a blood plate with a Taxo P optichin disc is set up to rule out S. pneumoniae at 24 hours |
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| What if yeast are seen in a blood culture? |
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| Sabaroud’s Dextrose agar for fungus is inoculated. |
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| What do you cleanse the puncture site of the blood culture bottle with? |
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| 70% isopropyl alcohol, iodine or chlorhexidine solution |
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| How much blood is collected from an adult for a blood culture? |
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| 10-20 mL |
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| How much blood is collected from an child for a blood culture? |
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| 1-5 mL |
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| What does times 2 order blood culture mean? |
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| For adults, an aerobic and anaerobic bottle make one set. These cultures are drawn at one site, while the other set is drawn at a different site, 10-20 minutes apart |
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| What does x2 blood culture help to determine? |
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| bacterial findings are the true source of a blood infection or a skin contaminant. |
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| Why do children only get one blood culture bottle drawn? |
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| lower blood volume of infants. |
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| skin contaminants in blood cultures |
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| Diptheroids, Proprionibacterium, Bacillus sp, Coag - staph, strep viridins |
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| Bacteria that infects catheter tip? |
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| s. epidermidis |
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| indicator of GI carcinoma |
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| Strep bovis |
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| What can LPS in GNRs cause? |
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| This endotoxin can cause septic shock and activate clotting factors resulting in DIC |
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| What does CSF do? |
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| surrounds the brain and spinal cord |
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| How much CSF is collected? |
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| 5-10 mL are collected in 4 sterile tubes for laboratory analysis. |
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| Tube 1 in CSF collection |
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| designated for chemistry testing |
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| Tube 2 or 3 in CSF collection |
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| bacterial culture |
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| tube 3 or 4 in CSF collection |
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| cell count in hemo |
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| Why should we not refrigerate CSF micro specimens? |
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| presence of fastidious pathogens |
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| How do microorganisms enter the CSF? |
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| a traumatic event, via a CNS shunt, the blood stream, oral cavity, ear, sinus or respiratory infection or through nerve transmission (rabies, herpes). |
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| What do you do if the CSF specimen is clear and more than 1 mL in volume |
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| centrifuged at 2500 -3000 rpm for 10 minutes before being processed |
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| How do you culture CSF sediment? |
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| to a blood, chocolate and Macconkey plate along with a thioglycollate broth and incubated in CO2. Along with a gram stain or cytospin |
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| Normal findings for CSF |
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| sterile with ‘no organisms seen’. |
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| Clinical findings in bacterial meningitis |
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| high white blood cell count (neutrophils), high CSF protein, low CSF glucose level |
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| Clinical findings in viral meningitis |
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| high white blood cell count (lymphocytes) |
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| CSF Pathogens |
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| Hemophilus influenza type B (Hib) N. meningitis - meningococcus (military barracks & college dorms) S. pneumonia – pneumococcus (CSF or urine EIA Ag test available) Listeria monocytogenes S. aureus Enterics Group B Strep – newborns |
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| How are sterile fluids obtained? |
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| with a syringe by a physician and sent to the lab in a sterile container. |
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| environments for sterile fluids |
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| aerobic or anaerobic |
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| Should sterile fluids be refrigerated? |
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| no |
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| Sterile fluid plates |
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| blood, chocolate and Macconkey plates as well as a thioglycollate broth |
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| Gram stain for sterile fluids? |
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| Yes |
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| Clear fluids >1mL in volume for sterile fluids |
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| centrifuged before culturing |
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| transudate |
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| excess fluid in a tissue |
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| exudate |
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| excess fluid resulting from inflammation. |
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| The normal finding for all blood cultures and fluids |
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| no organisms seen. These are naturally sterile sites |
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| Fluid pathogens |
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| S. epidermidis S. aureus S. pneumonia Beta hemolytic Strep H. influenza N. gonorrhea Enterobacteriaceae P. aeruginosa Acinetobacter spp. Borrelia burgdorferi (Lyme disease) Mycobacterium spp. Anaerobes Fungus |
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| How is skin compromised? |
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| infection by trauma or abrasion |
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| How are wound cultures received? |
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| swabs, in sterile containers as an abscess exudate or in the form of a tissue or bone biopsy. |
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| What do you do with large pieces of wound culture? |
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| tissue are cut with a scalpel and ground in a tissue grinder |
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| Normal skin flora |
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| Coagulase negative staph Diptheroids Proprionibactierium |
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| Wound pathogens |
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| Staphylococcus aureus (most common) Group A strep (Impetigo, flesh eating bacteria) Enterococcus spp. Enterobacteriaceae P. aeruginosa Eikenella corrodens (human bite) Pasturella multocida (cat & dog bites) Vibrio vulnificus (salt water wounds) Bacillus anthrasis (wool sorter’s disease) Erysipelothrix sp. Fungus, Parasites & Viruses |
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| Bacterial isolates from deep wounds and abscesses |
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| often anaerobic pathogens. |
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| sacral decubitus ulcers |
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| aerobic |
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| Anaerobic pathogens |
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| 1. Actinomyces spp 2. Bacteroides spp. 3. Clostridium spp. 4. Bifidobacterium 5. Fusobacterium spp. 6. Peptococcus spp. 7. Peptostreptococcus spp. 8. Proprionibacterium spp. 9. Prevotella spp. 10. Veillonella spp. |
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| How do respiratory cultures arrive to the lab? |
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| form of expectorated or induced sputum |
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| Aspirated sputum is in a |
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| Lukens tube or a bronchial lavage in a sterile container. |
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| What are respiratory specimens plated to? |
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| The specimen is plated to a blood, chocolate and Macconkey plate. Gram stains are done routinely on respiratory cultures |
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| Respiratory gram stains are assessed based on |
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| number to epithelial and white cells present. |
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| spit |
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| >25 squamous epithelial cells/LPF in the absence of white cells |
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| a good respiratory specimen |
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| The presence of white cells and columnar epithelial cells |
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| Exception in respiratory specimen |
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| no white cells because patient is neutropenic |
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| Infant respiratory specimens |
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| sterile |
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| Normal respiratory flora |
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| 1. Coagulase negative staph 2. Micrococcus sp. 3. S. aureus 4. Diphtheroids 5. Strep viridans 6. Enteroococcus spp. 7. Neisseria spp. 8. Haemophilus spp. |
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| Respiratory pathogens |
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| 1. Streptococcus pneumonia 2. Beta hemolytic strep 3. Staphylococcus aureus 4. Haemophilus influenza 5. Neisseria meningitis 6. Moraxilla catarrhalis 7. Enterobacteiacae 8. Pseudomonas aeruginosa 9. Acinetobacter spp. 10. Burkholderia cepacia 11. Bordetella pertussis – specialized media, DFA 12. Corynebacterium diphtheria – specialized media 13. Corynebacterium jekeium 14. Legionella spp. – Urine Ag EIA test 15. Mycobacterium spp. 16. Nocardia spp. 17. Mycoplasma pneumonia - EIA 18. Fungus 19. Parasites 20. Viruses |
