ClinLab Review Flashcards
What specimens need to be refrigerated if their delivery to the lab is delayed?
RUSS Respiratory specimens Urine Sputum Stool
What specimens need to be kept at room temperatures if their delivery to the lab is delayed?
Body fluids
Blood culture
CSF
What specimens need to be transported on special types of transport medias?
Viral- virus transport media
Stool- Carry-Blair media
Stool parasite- Formalin and Polyvinyl Alcohol
What are some of the reasons/criteria specimens can be rejected by the lab?
Improper label
Wrong container
Leakage
Unsuitable specimen
Duplicate/repeat specimen- exception= blood cultures for suspected endocarditis
Sterile body fluids not delivered STAT to lab
Kids and facial infections
Impetigo- nose and lips
Herpes- suckling infant w/ mouth sores
Herpatic whitlow
Infectious endocarditis
Inflammation of endocardium/endothelial surface of heart
Valves- if previously damaged
Congenital- affects A/P valves
Acquired- A/M valves
Acute ABE
Rapid/aggressive infective endocarditis occurring during septicemic episode on healthy cardiac valves
Skin flora- Staph A (MRSA)
IVDU- MRSA affecting tricuspid valve
Subacute SBE
Gradual infective endocarditis occurig in damaged cardiac calves (congenital, atherosclerotic, rheumatic)
Endogenous oral flora- Strep V or intestinal flora- S Bovis (GI CA)
Skin flora- Staph A
Culture negative HACEK Bacteria for Endocarditis
Haemophilus sp Aggregatibacter Cardiobacerium Eikenella Kingella
What is the significance of positive blood culture results?
True += growth of same organism in repeated cultures
Different organism, different bottle= probable contamination w/ bowel spillage
Growth of normal skin flora= contamination (coag neg staph, coryn, bacillus, propion)
V. Strep/Enterococci- possible endocarditis
Considerations for choosing antibiotics for PTs
Antibiogram- collection of info obtained from C&S performed in an institution within a time frame (annual)
Provides % of samples for a given organism which were sensitive to a certain ABX
What info is not provided by an antibiogram?
Organism sensitivity to an ABX base on site of infection, location in hospital, average MIC, killing at dose/concentrations
How do we determine the ABX drug of choice for PTs?
Susceptibility
Cost
Availability
What organism is at the top of the antibiogram data sheet and what drugs is it most/least susceptible to?
E Coli-
Nitrofurantoin, Cephalothin
IgM present in immunoglobulin testing indicates?
Current infection
IgG present in immunoglobulin testing indicates?
Current infection- acute and convalescent
Precious exposure- vaccine or old infection
IgA present in immunoglobulin testing indicates?
Celiac Dz
Hepatitis
IgE present in immunoglobulin testing indicates?
Allergen testing
IgD present in immunoglobulin testing indicates?
Unknown function/purpose
Define Titer
Way of expressing concentration by serial dilution to obtain approximate quantitative information to compare acute vs convalescent sera
Corresponds to highest dilution factor that still yields + reading (4x inc=acute)
What happens if only an acute sample is submitted for a titer?
Cut off value is required and can vary by organism/geography
What is a Primary Titer response?
What is a Secondary/Re-Exposure Titer?
Day 5- 1:4
Day 12- 1: 4
1:256 or higher
What happens during each phase of a Hep A infection?
Incubation- 15-45 days, relative titer levels, HAAG
Early acute- 0-14 days, AST/ALT 1-2mon, Sx, anti-HAV IgM and Total anti-HAV rise parallel
Acute- 3-6mon, toal anti-HAV plateuas, anti-HAV IgM falls off
Recovery- years later, no anti-IgM, only Total anti-HAV present
What globulins are present in a susceptible person?
HBsAg neg
anti-HBc neg
anti-HBs neg
What globulins are present in a person immune due to natural infection?
HBsAg neg
anti-HBc pos
anti-HBs pos
What globulins are present in a person immune due to a Hep B vaccine?
HBsAg neg
anti-HBc neg
anti-HBs pos
What globulins are present in a person that is acutely infected w/ Hep B
HBsAg pos anti-HBc pos anti-HBs neg IgM anti-HBc pos ALT elevated
What globulins are present in a person that is chronically infected w/ Hep B
HBsAg pos anti-HBc pos anti-HBs neg IgM anti-HBc neg ALT elevated
What will CSF results look like in bacterial meningitis?
PMNs
Low glucose
High Protein
What will CSF results look like in viral meningitis?
Normal glucose
Moderate inc protein
What will CSF results look like in fungal meningitis?
Lymphocytes
Low glucose
High protein
What will CSF results look like in parasitic meningitis?
Eosinophils
Norm/low glucose
High protein
What bacteria cause the most cases of meningitis in elderly?
Strep penumo E Coli K pneumoniae S agalactiae L monocytogenes
What bacteria cause the most cases of meningitis in Adults?
Strep pneumo N meningitidis Staph H influenza G Bacilli Strep L monocytogenes
What bacteria cause the most cases of meningitis in children?
Strep pneumo
N meningitidis
H influenzae
What bacteria cause the most cases of meningitis in neonates?
S agalactiae
E coli
L monocytogenes
Strep
What is the most common cause of UTIs in females and males?
E Coli- most common cause
S. Saprophyticus- young, sexually active
Enterbacteriaceae
What is the most common cause of recurrent UTIs?
Proteus Psudomonas Klebsiella Enterbacter Entercoccus Staph
Define uncomplicated cystitis and how is it diagnosed?
+12y/o female non-pregnant, no fever, N/V or flank pain
Dx w/ dipstick UA
Define Complicated Cystitis and how is it diganosed?
Female w/ comorbid medical condition or ALL male PTs Indwelling foley catheter Urosepsis Hospitalization Dx w/ UA and culture
How is pyelonephritis diganosed?
UA
Culture
CBC
Chemistry
Which microbes cause urethritis?
Gonococcal- N Gonorrhea
Non-Gonococcal- Chlamydia trachomatis, Mycoplasma, Ureaplasma (Adenovirus, Trichomonas Vaginalis, HSV)
What is the “traditional” UTI?
Which one is sexually transmitted?
Cystitis
Urethritis
What type of sample is sent for urethritis caused by chlamydia trachomatis?
UA
Culture
+ pyuria, - bacteria= chlamydia
What type of samples are sent for urethritis caused by N. Gonorrheae
UA and Culture
Pelvic exam d/c for gram stain, culture and PCR
What specimens are sent for urethritis?
Urethral/cervical swab
Urethral d/c
First void urine- 3 ml or more
Possibly- rectal or pharyngeal swab
What type of Gram stain is positive for Sx males?
+ Gram Negative Diplococcie and WBCs
Define Gardnerella Vaginalis
Bacterial vaginosis Malordorous gray/white d/c Possible UTI or ASx pH>4.5 \+ amine test Clue cells seen on saline wet prep
Increase in vaginal pH suggests what two things?
Bacterial vaginosis
Trichomoniasis
Define Candidiasis
Candida albicans- pseudohyphae
Intense itch w/ cottage cheese
Dysuria
Normal pH
Define Trichomoniasis
Trichomonas vaginalis Frothy green/yello d/c Requires motile organism Inc pH 5.0-6.0 Strawberry cervix Vaginal soreness/dyspareunia Often ASx
How is vaginal pH measured?
Narrow range pH paper
Amine test is AKA?
Whiff test
KOH, inc pH, fishy smell
Function of microscopy when evaluating vulvovaginitis lab tests?
Saline wet prep
Jerky Trichomonoas
Clue cells- bacterial
Budding yeast- fungal
Function of KOH prep when evaluating vulvovaginitis lab tests?
KOH destroys cell walls of bacteria but not fungi/yeast
What are the two spirochete for memory?
Treponema pallidum- Syphilis
Borrelia burgdoferi- Lyme Dz
Syphilis direct testing
Skin, placenta, unbilicus
Dark field microscopy
Definitive Dx
Syphilis non-treponemal tests
Screening of serum
RPR, VDRL (CSF)- titer
+Sensitive - Specific
Syphilis treponemal test
Confirmation of serum
FTA-ABS, MHA-TP, TP-PA
+ result for life
Steps of syhpilis screening test
- RPR looks for non-specific Abs cardiolipin
- RPR titer
- F/u + w/ confirmation
MHA-TP or FTA-ABS
What do the results of a syphilis RPR mean?
Pos RPR 1:16 + Neg confirm- false pos RPR
Pos RPR 1:16 + Pos confirm= active Dz
What is the follow-up syphilis testing?
Non-treponemal test
Titer of Ab/activity of Dz
What is important part of the follow up process of syphilis?
Serologic monitoring
Suggested at 3 6 and 12mon intervals after Tx and must be done w/ same testing assay (RPR or VDRL) for all f/u exams
Syphilis testing review has two paths to choose
Conventional nontreponemal (VDRL/RPR) then treponemal (TP-PA/FTA-ABS) Reverse treponemal then nontreponemal
What did the CDC change about treating gonorrhea?
Cefixime is not first line for treatment
Characteristics of Chancroid
Haemophilus Ducreyi Painful ulcer w/ tender inguinal nodes Necrotic/purulent base w/ ragged borders School of fish/railroad track morphology Dx w/ culture and neg for HSV testgin
What is the most common STD in the US?
HPV genital warts
Define Condyloma Acuminatum
Type 6, 11 Anogenital warts in wo/men
HPV can lead to epithelial carcinoma of the ? and what types?
Cervical cancer
Low risk- 6 and 11
High- 16 18 31 33 35
What med is FDA approved for use in males and females 9-26 for HPV?
Gardasil for types 6 11 16 18
How is HPV Dx
Visual ID- 3-5% acetic acid
Cytologic exam of cervical cells
Molecular ID- anogenital PAP smear- hybrid capture method for ID
PAP smears can ID what types of cancer?
Cervical
Uterine
Ovarian
Define PID
Endometriosis, salpingitis, tuboovarian abscess and pelvic peritonitis
Usually complication of cervicitis (Gonorrhea or C trachomatis)
What are the consequences of PID?
Infertility
Ectopic pregnancy
Abscess formation
Chronic pelvic pain
How isa PID diagnosis confirmed?
NAT
What are the essentials of a HIV diagnosis?
RNA detected/quantitated by PCR of bDNA
Low CD4
Unexplained opportunistic
How long does it take for an HIV infection to take place?
Average detection within 25 days
Within 3mon of + status
4th generation assays can detect withing 12 days
What are the confirmatory tests for HIV 1 and HIV 2
Western blot- HIV 1
Bio-Rad Multispot- HIV 2
Qualitative RNA PCR
What does it mean if a 3rd blood specimen is submitted for HIV confirmation and it comes back negative?
PT is not infected
When is a Western Blot assay used?
Detect proteins as confirmatory test for + HIV EIA results
RIBA for HCV or Lyme Diz
HIV indeterminant status positive results require Abs against ?
One envelope protein
One core protein or one enzyme protein
After PT tests positive for HIV what is the next step?
Determine baseline viral load
CD4 levels
Screen for TB/Hep viruses
PTs at risk for HIV should also be tested for ?
Hep ABC STIs Herpes TB CXR
HIV screening is done with ?
ELISA
S/Sx of influenza
PTs always have fever, HA and muscle aches
Dry cough
S/Sx of URI
Hacking cough
Fever in kids
Rare HA
Sneezing and sore throat
Bacterial vs Viral pharyngitis
Bacterial (GAS)- younger, sudden onset, HA, vomit, fever
Viral (Coxsackie)- young adults, slow progression, cough, low fever, conjunctivitis w/ Adenovirus
Strep pharyngitis is caused by ?
GAS
Abrupt sore throat, high fever, HA
Huge, swollen tonsils
What are the 3 sequelaes of strep pharyngitis
Scarlet fever
Rheumatic fever
Glomerulonephritis
Centor Criteria
Tonsil exudate Cervical adenopathy Fever Absent cough 3 or more Sx= swab
S/Sx of Strep Pyogenes
Scarlet fever
Starts w/ fever and sore throat
Strawberry tongue
S/Sx of Acute Glomerulnephritis
10-14 days post infection
Fluid retention, HTN and edema
Sx= hematuria, foamy urine, swollen face/ankles/feet/legs
S/Sx of rheumatic fever
Kids 6-15y/o starting 20 days after strep/scarlet fever
Polyarthritis, carditis, nodules under skin, rapid jerky movement
Skin rash
Pharyngitis by Mycoplasma pneumoniae
Young adults w/ HA, pharyngitis and lower respiratory Sx
75% have cough= distinctive from GAS infection
Pharyngitis by Chlamydia pneumoniae
Pharyngitis precedes pulmonary infection by 1-3wks
Pharyngitis by Neisseria gonorrhoea
Rare cause of pharyngitis
Pharyngits by Corynbacterium diphtheriae
Foul smelling gray membrane that can lead to airway obstruction
Pharyngitis by Arcanobacterium haemolyticum
Similar to GAS and is identical on culture
Gram stain resembles Corynebacterium
What causes most cases of pharyngiits
Viruses
EBV, Adenovirus and Coxsackie A virus
What are the S/Sx of viral pharyngitis
Enlarged tonsils
White exudates
Cervical lymphadenopathy
Coxsackie- also has herpetic vesicles in posterior pharynx
S/Sx of adenovirus pharyngitis
Conjunctivits and pharyngitis
AKA Pharyngoconjunctival fever
S/Sx of Herpes Simplex pharyngitis
Herpangina- vesicular lesions
In older PTs can be indistinguishable from GABHS infection
S/Sx of Coxsackie virus pharyngitis
Like herpes w/ white nodular vesicles in oropharynx
S/Sx of EBV pharyngitis
Mono, looks like a GAS infection
Exudative pharyngitis, retrocervical or adenopathy and hepatosplenomegaly
S/Sx of Cytomegalovirus
Older, sexually active PTs w/ higher fever and more malaise
Pharyngitis is not the prominent complaint
S/Sx of HIV-1 pharyngitis
Like mono
Edema, erythema, aphthous ulcers
Lymphadenopathy, fever, myalgia
Characteristics of Laryngotracheobronchitis
Croup from Parainfluenza virus
Inspiration stridor, non-productive barking cough w/ Sx worse at night
Nasal wash submitted to lab for culture/PCR
Characteristics of Epiglottitis
HIB cause the three Ds- dysphagia, drooling, distress
Hot potato voice
Tripod posture
CBC, blood and epiglottal cultures- ALERT lab for special growth media
Characteristics of Diphtheria
Toxin producing strain of Corynebacterium Diphth.
Hallmarks: thick gray/black fiber-like pseudo-membrane on tonsils, uvula and palate
Sudden onset w/ fever, bull neck and low fever
Treat w/ antitoxin prior to confirmation
+ culture and toxin assay
Alert the lab, reqs special media for growth
How is diphtheria spread?
Resp droplets
Fomites
Food
Where does diphtheria first appear?
Skin
The Iditarod Dog race is done in honor of what disease outbreak?
Diphtheria
Characteristics of Pertussi
Bordatella pertussis
B Parapertussis
Sx after 7-10 day incubation, starts w/ paroxysms coughing bouts w/ final whoop noise
Adults are main carriers w/ chronic cough
Alert lab, reqs special growth media
What are the 3 stages of Pertussis
Catarrhal- common cold, most infectious time
Paroxysmal- whooping, mucus production
Convalescent- parosyxms reduce and secondary complications occur
How is a lower respiratory tract specimen collected?
Expectorated/Induced Sputum: PT breathes aerosolized 15% sodium chloride and 10% glycerin x 10m FIRST thing in morning
Gasric aspirate- only for acid fast bacilli isolation in PTs unable to make sputum
What causes bronchiectasis
Destruction and widening of large airways
Begins in childhood after infection or foreign object inhalation
Congenital- by CF (Burkholderia, Staph A or P Aeruginosa)
Acquired through COPD
What type of specimen is needed for a bronchiectasis Dx
Sputum for culture
Characteristics of The Common Cold
Coronavirus, Adenovirus- pharyngitis, Rhinovirus
Most frequent human disease from contact w/ infected mucoid secretions
Common causes of bacterial pharyngitis
M pneumo C pneumo N gonorrhea C diphtheria A haemolyticum
Common causes of viral pharyngitis
Adeno Coxsackie EBV HSV Cytomegalo HIV
What microbes cause Traveler’s Diarrhea
Shigella Salmonella Campylobacter V Cholerae EIEC, EHEC, EPEC, ETEC
