agents of the throat
-Viruses-Streptococcus pyogenes (Group A Streptococcus)-Other bacterial causes, though not as common as group A-Candida albicans
specimen collection of the throat
-Posterior pharynx-Avoid normal oropharyngeal flora-Collect two swabsoInoculate blood agar plateoRapid testing for GAS antigen
agents of the nasopharyngeal
-Bordetella pertussis, Influenza virus, Coronavirus
carrier state of the nasopharngeal
-Staphylococcus aureus-Neisseria meningitidis
specimen collection of the nasopharyngeal
-Flexible thin wire swab guided into nares to posterior pharynx
specimen of oral cavity
-Gingivitis and dental caries
specimen of middle ear
-Otitis media-Predictable pathogens, rarely cultured-S. pneumoniae and H. influenzae most common
specimen of sinuses
-Direct sinus aspirations, washes-Predictable pathogens, rarely cultured
lower respiratory tract specimens
§Bronchitis or pneumonia
agents of lower respiratory tract
-Viruses-Streptococcus pneumoniae, Klebsiella pneumonia, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, anaerobes-Mycoplasma pneumoniae (walking pneumonia)
specimen collection of lower respiratory tract
-Expectorated sputum, endotracheal specimens, translaryngeal aspirates, bronchoalveolar lavage
What is used to evaluate sputum samples?
BartlettsPMNSEC
What plates are used for sputum?
MAC and CHOC
What agents are in the gastrointestinal tract?
-Rotavirus, Norovirus-Parasites-BacteriaoVerotoxic E. coli, Salmonella, Shigella, Campylobacter, Vibrio, Yersinia enterocolitica
What samples are taken from the gastrointestinal tract?
stool and rectal swab
How is stool sample processed?
-Usually contains many species of facultative and anaerobic normal flora-Wide mouth container with tight fitting lid-Commercial transport media available to preserve specimen
Is a gram stain for white cells used in stool samples?
no
How are stool samples plated?
-Blood, MAC, Xylose-lysine-desoxycholate (XLD), selenite (enrichment) broth-No anaerobic media
What agents are in urine?
-E. coli and other Enterobacteriaceae (Proteus, Enterobacter, Klebsiella); Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus, S. saprophyticus
How are urine samples collected?
-Transport tube with preservative (boric acid-glycerol) is available if delivery delayed-Clean catch midstream preferred
What plates are used for urine samples?
to blood and MAC
What agents are in blood?
-Staphylococcus aureus, S. epidermidis, Enterococcus, E.coli and other Enterobacteriaceae-Candida albicans and other species
How is the skin protected when collecting blood?
-First scrub with 70% alcohol for at least 60 seconds-Second apply 2% chlorhexidine (preferred) or 2% tincture of iodine in concentric circles-Culture bottle tops cleaned with alcohol before inoculation with blood specimen
How often is blood collected?
§Collect two sites at least one hour apart because number of bacteria per mL may be low-Collect at least 20 mL of blood per set-Usually no more than 3 sets per 24 hours
What do the blood collection bottles contain?
-polyanethol sulfonate (SPS) anticoagulant
What do the set of blood containers consist of??
§A set of bottles consists of one aerobic and one anaerobic bottle, though at least one aerobic bottle is necessary
What agents are in CSF?
-Neisseria meningitidis, Haemophilus influenzae, Streptococcus agalactiae-Viruses-Fungi
What are the collection of CSF?
-Needle aspirate from third or fourth lumbar vertebra-Three to four tubesSTAT
What plate should CSF go on?
blood, CHOC andinoculate a thioglycolate broth
What agents are in the genital tract?
-Neisseria gonorrhoeae, Treponema pallidum (syphilis) Herpes Simplex Virus type 2, Chlamydia trachomatis, Trichomonas vaginalis
What is the collection of genital tract for females?
oLower genital tract: swaboUpper genital tract: aspiration or biopsy
What is the collection method of genital tract for males?
oLower genital tract: swaboUpper genital tract: aspiration or biopsy
What plate is gonorrhea plated on>
oMartin Lewis or Modified Thayer Martin media
Agents in wounds
-Staphylococcus aureus, Enterococcus, gram-negative bacilli, anaerobes, fungi
What is the collection method of wounds?
-Need exact anatomic site where specimen was taken-Aspirates, purulent drainage, tissue-Recommend needle aspirates over swabs
What do wounds get plates on?
with blood, MAC, CHOC, and thio broth
What is the goal of specim trasport?
-Two-hour limit to specimen receipt-Transport media such as Stuart's, Amies, and JEMBEC may be used to maintain viable cells
What can cause a specimen to be rejected?
-improperly labeled-in unsuitable container-accompanied by improper request-of insufficient quantity-received more than two hours after collection
What can neutrophils and epitheliel cells mean?
-Neutrophils ~ infection-Epithelial cells ~ contamination
What is brightfield microscope?
all methods
What is phase contrast microscopy?
unstained slides, motlity
What does saline mount identify?
-Observe bacterial motility-Observe Trichomonas vaginalis in urine
What does iodine mount indentify?
ova and parasites in stool
What does KOH identify?
skin and nails
What does the India ink stain?
Cryptococcus neoformans
What is the simple stain of a mount?
methylene blue
Blood agar plates
-Trypticase soy agar with 5% defibrinated red blood cells-SourceoPrefer sheep blood agar (SBA)oHorse or rabbit blood give different results-Grows most significant pathogens
Hemolysis
-Observe at surface and also "stab" agar to observe subsurface hemolysis.-AlphaoIncomplete or greening or browning-BetaoComplete clearing-Non hemolyticoNo change to red blood cells
Chocolate agar
-Red cells are hemolyzed by enzyme or heat to release NAD and hematin-Enriched with IsoVitaleX and other nutrients-Isolates fastidious bacteria, such as Haemophilus-Will grow nearly all bacteria
§Thioglycollate broth
-Growth and differentiation of aerobes and anaerobes
§MacConkey Agar
-Isolates gram-negative bacteria-Differentiates fermentersoLactose fermenters§PinkoNonlactose fermenters§Clear
§Eosin methylene blue plate
-Isolates gram-negative bacteria-Differentiates fermenterssoStrong lactose fermenters such as E. coli§Green metallic sheeno Lactose fermenters§PurpleoNonlactose fermenters§Clear
§Hektoen Enteric (HE) and xylose lysine deoxycholate (XLD)
-Inhibit normal microbiota of colon-Enhance isolation of stool pathogens-Differentiate based on ability to ferment carbohydrates, production of H2S
§Colistin nalidixic acid (CNA) and phenyl ethyl alcohol (PEA) agars
-Blood agar with antibiotics added-Selects for gram-positive bacteria and inhibits gram-negative bacteria
§Modified Thayer Martin (MTM) and Martin Lewis
-Chocolate agar base with antibiotics added-Selects for Neisseria gonorrhoeae and inhibits gram-positive bacteria, other gram-negative bacteria, and yeast
What is the Order of Inoculation?
oSpecimens that require immediate attention include cerebrospinal fluid, body fluids, and blood-Media OrderoLeast selective media inoculated first - blood or chocolate firstoSolid media inoculated before broth
How is a urine count conducted?q
blood agar plate10uLincubate 24 hoursmultiplying by 1000 or 100 to find CFU/mL§Values > 1.0 X 105/mL indicate infection
What is the -Mesophilic temperature needs?
oHuman bacterial pathogens grow best at 35 + 2oCoFungal cultures usually incubated at 25 - 30oC
What should the humidity be?
70%
What are the methods for microorganism identification?
phenotype, immunologic,genotype
When is colony microscopy examined/
18-24 hours after incubation