ClinLab 3: Final Final Review Flashcards
What samples need to be refrigerated if their delivery to the lab is delayed?
Respiratory
Urine
Sputum
Stool
What samples need to be maintained at room temps if their delivery to the lab is delayed?
CSF
Body fluids
Blood cultures
What criteria will get samples rejected by the lab?
What is the exception?
Improper label or container Leakage Unsuitable specimen Duplicates- unless blood culture for endocarditis Body fluids need to be delivered stat
What infections can kids get from sucking/oral route
Roseola- droplet transmission Herpes- herpetic whitlow Giardia Hep A Otitis Media
Define acute endocarditis
Serious/aggressive septicemic episodes on healthy cardiac valves (catheter) from skin flora, Staph A/MRSA
IVDU- affects tricuspid valves
Define subacute/gradual endocarditis
Occurs in damaged cardiac valves from congenital defects, atherosclerosis, rheumatic fever
What microbes can cause subacute/gradual endocarditis
Endogenous oral flora: Strep Viridians (S mutans/mitis/snaguis/milleri) Intestinal flora (S bovis – suggestive of gastric cancer) Skin flora: Staph aureus
What are the HACEK microbes that commonly cause endocarditis
Haemophilus species Aggregatibater Cardiobacterium Eikenella Kingella
S/Sx of bacteremia, endocarditis and sepsis?
These samples need to be taken prior to ?
Sx: fever, leukocytosis, N/C
Collect before antibiotic therapy
Define a Blood Culture Set
1 “set” = 1 aerobic and 1 anaerobic bottle
Different sites/times
No more than 4 total sets w/I 24 hours
Pediatric patients 1 bottle
What is the significance of a positive blood culture?
Growth of the same organism in repeated culture: True positive
Growth of different organism in different culture bottles: Contamination, bowel spillage
Growth of normal skin flora – likely contamination w/ Coagulase negative Staph, Coryn, Bacillus, or Propion
Organisms like Viridians Streptococci or Enterococci= possible endocarditis – associated w/ low grade symptoms
What must be done after the receipt of blood culture results?
Always match culture results with S/Sx
Define Antibiogram
Info obtained from C&S performed in the institution in given time– antibiogram is annual.
Provides % of samples for organism which were sensitive to certain antibiotics
What info do Antibiograms not provide?
Organism sensitivity to an Abx based on the site of infection
Organism sensitivity based on location in hospital (ICU vs non-ICU)
Average MIC
Abx killing at various doses/concentrations – trend data
What pitfalls come with Antibiograms?
Concentration differences between site of infection and in vitro
Penetration to the site of infection Inactivation of drug at site of infection Declining levels in vivo vs continuous levels in vitro
Rapid development of resistance in vivo vs in vitro
FQ and MRSA
Erythromycin induced clindamycin resistance Inaccurate due to small isolate number
What is encompassed in Antibiogram data?
DOC- susceptibility, cost and availability
Define Passive Immunity
Resistance based on Abs preformed in another host
Administration of Ab against toxins makes large amounts of antitoxin immediately available to neutralize the toxins or limits viral multiplication
Other forms of passive immunity= IgG passed in pregnancy and IgA passed during breast feeding
What is the main advantage of passive immunity?
What are the disadvantages?
Prompt availability of large amounts of Ab;
Disadvantages= short life span of these Abs and possible hypersensitivity reactions if globulins from another species are used
What are the immunoglobulin classes and what’s their meanings?
IgM: Current infection
IgG: Current infection, Acute and convalescent, Previous exposure (Vaccinated or old infection)
IgA : (secretory) Celiac disease, hepatitis
IgE: Allergen testing
Define Primary and Secondary Immunity?
Primary: IgM binds first, specific IgG binds later, makes more IgG specific for that Ag
Secondary: IgM and IgG (memory) react simultaneously
Define Titer
Method of expressing concentration
Employs serial dilution to obtain approximate quantitative information
Corresponds to the highest dilution factor that still yields a positive reading.
Often compares acute vs convalescent
What does a 4x increase of a titer mean?
Acute infection
What happens if only an acute sample is submitted to the lab?
Cut off value is required
Varies by organism and geography
Define Primary Response Titer
Define Secondary Response Titer
Day 5 1:4 titer
Day 12 1:64 titer
Re-exposure Titier: 1:256 titer or even higher
S/Sx of Hep A-E infection include ?
Abd pain/distension Breast development (males) Dark urine Clay stool Fatigue Low fever Generalized itching Jaundice N/V, weight loss
What labs are drawn to test for acute hepatitis?
IgM anti-HAV IgM anti-HBc HBsAg anti-HCV LFTs- based on screening
What will PE of PT with acute hepatitis show?
Large/tender liver
Fluid in abdomen
Yellow skin/eyes
What is included in a lab work up for acute hepatitis?
U/S Autoimmune blood markers Serologies LFT Biopsy, Paracentesis (if fluid present)
Characteristics of Hep A
Fecal-oral, high incidence in developing countries with low hygiene standards
Self-limited, no chronic liver dz
At risk: MSM, IVDU, Pts w/ clotting factor disorders
Labs: acute hepatitis A: anti-HAV IgM (+), anti-HAV IgG (+)
Resolved hepatitis A: anti-HAV IgG (+)
Characteristics of Hep B
Spread by contact w/ blood, semen, vaginal fluids. Vaccine available
Shared needles, toothbrushes, razors, nail clippers
Acute or chronic. Chronic can be active or inactive “carrier”
Characteristics of Chronic Hep B
Clinical evidence: no Sx required. Chronic infection covers a spectrum from no Sx to cirrhosis
Labs: IgM Anti HBc (-) AND HBsAg (+) or HBV DNA (+) or HBeAg (+) OR HBsAg (+) or HBV DNA (+) or HBeAg (+) twice at least 6 months apart (any combination is acceptable)
Confirmed case: meets lab criteria alone
Presumed: Pt w/ single HBsAg (+) or HBV DNA (+) or HBeAg (+) and does not meet acute case definition
Characteristics of Hep C
Blood/Vertical spread (mom to baby)
Most develop chronic disease
Active infection: Anti-HCV EIA: screening (+), Anti-HCV RIBA: confirmatory (+), qualitative HCV RNA (+)
EIA assay (screening) to detect HC-Ab, confirmed by RIBA or HCV RNA
Hep C RNA assays measure virus levels (viral load) to measure response to therapy
Hep C genotype: 6 of them. Most Americans have genotype 1. 2 and 3 respond to therapy
Immunoglobulins in PTs that are susceptible
HBsAG neg
anti HBc neg
anti HBs neg
Immunoglobulins in PTs that are immune from natural infection
HBsAG neg
anti HBc pos
anti HBs pos
Immunoglobulins in PTs that are immune from Hep B vaccination
HBsAG neg
anti HBc neg
anti HBs pos
Immunoglobulins in PTs that are acutely infected
HBsAG pos
anti HBc pos
anti HBs pos
IgM anti-HBc neg
Immunoglobulins in PTs that are chronically infected?
HBsAG pos
anti HBc pos
anti HBs neg
IgM anti-HBc neg
Characteristics of HBsAg
HBV is in the body of the patient
Acute: serology turns negative with development of anti-HBs
Chronic: HBsAg is persistently positive
Characteristics of anti-HBs
Produced in response to HBsAg
Presence indicates either an infection or vaccination Vaccine is essentially HBsAg
Anti-HBs hangs around for a long time, decreasing gradually with age
Characteristics of HBeAg
Comes from the core of the HBV
When the core degrade in the serum, Ag is created and can be detected, although not all Pts will have a detectable HBeAg
If HBeAg is (+), it is equivalent to a positive HBcAg marker and shows that the BPV is replicating actively and the patient is infectious
Characteristics of Anti-HBe
Body’s immune reaction to HBeAg
Presence indicates HBV replication activities have decreased and the Pt is less infections/not infectious at all
Characteristics of HBcAg
Totally degraded in the serum and is not detectable, but a portion survives as HBeAg
Characteristics of IgM anti-HBC
FIRST immune response against infection, indicates active infection or flare against natural exposure
Immune response matures, this is replaced by IgG anti-HBc
Anti-HBc is absent in those who have been vaccinated
Define Total Anti-HBc
Made in response to HBcAg, refers to presence of either IgG or IgM and does not discriminate
Presence indicates prior or current Hep B infection
Characteristics of HBV DNA
Indicates active infection (acute or chronic)
Used as a quantitative test to monitor response to therapy, mainly in chronically infected patients
“Viral load”
What test results show active syphilis
+ non-treponemal test (screening)
+ treponemal test (confirmatory)
What test results show a false positive RPR
+ non-treponemal test (screening)
- treponemal test (confirmatory)
What test result show Spirochete or previous syphilis
- non-treponemal test (screening)
+ treponemal test (confirmatory)
What can cause bacterial traveler’s diarrhea
Salmonella
Campylobacter
Shigella
What can cause viral Traveler’s Diarrhea
Rota
Noro
Enteric adeno
Astro
What can cause parasitic traveler’s diarrhea
Giardia Cryptosporidium Cyclospora Isospora Balantidium Entamoeba histolytica
What causes microbes can cause Traveler’s Diarrhea
Shigella EIEC, EHEC, EPEC, ETEC Salmonella Campylobacter V Cholera
What microbe specifically causes Traveler’s Diarrhea
ETEC from contaminated food/water
Cramps and watery diarrhea
What are the Traveler Infections
Typhoid fever Leishmaniasis Yellow fever Dengue fecer Leptospirosis Meningitis
Upper UTIs include ?
Lower UTI is called ?
Pyelonephritis
Cystitis (“traditional” UTI)
Urethritis (often STI)
Prostatitis
What causes Cystitis and what are the two types?
E coli, staph saprophyticus, proteus mirabilis, klebsiella, enterococcus
Uncomplicated- Healthy adult women (>12), non-pregnant, no fever/N/G/flank pain dx w/ dipstick UA
Complicated- Females w/ comorbidities, ALL males, indwelling foley catheters, urosepsis/hospitalization
Dx w/ UA and culture
Define Pylonephritis and the S/Sx
How is it diagnosed?
Infection of kidney presenting w/ Fever, N/V, HA and flank pain
Dx w/ UA, culture, CBC and chemistry
What are some complications that can arise from untreated pyelonephritis?
Perinephric/renal abscess- suspected in PTs not improving on ABX
Dx- CT w/ contrast, renal US
Characteristics of nephrolithiasis w/ UTI
PTs w/ severe flank pain
Consult w/ urology
S/Sx of Protatitis
How is it diagnosed
Sx: pain in perineum, lower abdomen, testicles, penis, and with ejaculation, bladder irritation, bladder outlet obstruction, sometimes blood in semen
Dx w/ Hx (fevers/chills/dysuria/malaise/myalgias/pain/cloud urine) Tender prostate on PE. Increased PSA. UA and urine culture
Risk factors: Trauma, sexual abstinence, dehydration
What causes urethritis?
Chlamydia trachomatis
Neisseria gonorrhea
S/Sx of Chlamydia trachomatis urethritis
Frequently asymptomatic in females, but can present w/ dysuria, discharge, or PID
Send UA, urine culture (if pyuria seen, but no bacteria, suspect chlamydia)
Pelvic exam – send discharge from cervical or urethral site for chlamydia PCR
Chlamydia screening is now recommended for all females 25 or under
S/Sx of Gonorrhea urethritis
May present w/ dysuria, discharge, PID
Send UA, urine culture. Pelvic exam – send discharge samples for gram stain culture, culture, PCR
You should always also treat for chlamydia when treating for gonorrhea!
How is Gonorrhea urethritis diagnosed and with what specimens?
Specimens: urethral/cervical swab, urethral discharge, urine (first void).
Dx urethritis/cervicitis: gram stain. Culture (100% specificity), serology (useful for diagnosis of LGV caused by C. Trichomatis), nucleic acid amplification (can test both GC and Ct simultaneously, very sensitive and specific)
What is the most common cause of urethritis in females?
What are the S/Sx and causes of recurring infections?
E coli
S saprophyticus in young sexually active females.
Cystitis, pyelonephritis.
Recurring infections – reinfection pathogens: proteus, pseudomonas, klebsiella, Enterobacter, enterococcus, staphylococcus
What is the most common cause of urethritis in males?
What S/Sx are seen on PE for Dx?
Enterobacteriaceae. Very low prevalence. S/Sx: urethritis (sterile culture: discharge, dysuria, frequency), prostatitis (obstructed urine flow: “complicated UTI”)
PE: CVA tenderness (pyelonephritis). Urethral discharge (urethritis) Tender prostate (prostatitis)
