Exam VI - Blood, Brain, and Urine

Question 1

Rickettsia: General Information

Answer 1

obligate intracellular organism (also erhlichia and anaplasma
gram - coccobacilli (rods)
vector: arthropods
main symptoms: fever, rash, and headache
visualization: Giemsa stain aka blood smear
Dx: serology

Rickettsia species: rickettsii, akari, prowazekii, typhi, and orienta tsutsugamushi

Question 2

Rickettsia rickettsii

Answer 2

Rocky Mountain Spotted Fever
Vector: Dog and Wood tick
Reservoir: wild rodents
Geography: name is misleading more common in southeastern U.S. due to presence of ticks
Season: April to September

Incubation: 1 week
transmission: tick to tick is transovarial (passed on to subsequent generations), then transfers to humans
symptoms: centripetal rash that starts on extremities then spreads to the torso with petechial spots from blood vessel damage, headache, fever, conjuctival redness, and myalgia
Dx: microimmunofluorescence (MIF) that detects Ab
high mortality rate: 10-25%

Question 3

Rickettsia akari

Answer 3

Rickettsial pox (like chicken pox)
vector: mites
reservoir: mice
disease: mild and self limiting (immune response cures)
sign + symptoms: papules that progress to water filled vesicles
9-14 days later, high fever, headache, chills, photophobic, and increased amount of vesicles that become crusty

Question 4

Rickettsia prowazekii

Answer 4

Epidemic typhus
vector: body lice
reservoir: humans (horizontal transmission)
conditions: war, army, refugee camps, poverty, natural disaster, etc.
signs + symptoms: 8 days- headache, fever, and chills, then 4-5 days later patient develops small pink flat macules on trunk that spread outwards (centrifugal rash), but NO rash on soles, palms, and face

Question 5

Rickettsia typhi

Answer 5

Endemic typhus aka murine typhus (occurs all the time)
Vector: flea
Reservoir: rodents
Geography: worldwide in warm, humid areas, especially U.S. Gulf coast
Seasonal: warm months
Incubation period: 10 days
Signs & Symptoms: fever, headache, rash on chest and abdomen
Low mortality even in untreated

Question 6

Orientia tsutsugamushi

Answer 6

Scrub typhus
Geography: Asia and southwest pacific
Vector: chiggers in sandy soil
reservoir: rodents
Incubation: 2 weeks
Signs & Symptoms: high fever, headache, myalgia, scab at bite, flat maculopapular rash develops

Question 7

Borrelia burgdorferi

Answer 7

Spirochete- best place to look is in salivary glands
Lyme disease: most commonly reported tick borne illness in the U.S.
Vector: tick
Reservoir: white-footed mice, white-tailed deer
Geography: Northeast U.S.; Great Lakes region
Dx: EIA or IFA + then Western Blot; must have two positive tests; if negative results and signs and symptoms persist, then retest using convalescent serum

Question 8

Stages of Borrelia burgdorferi

Answer 8

Stage 1: localized bulls-eye rash and flulike symptoms for 2-3 weeks

Stage 2: disseminated to the body causing fatigue, migratory joint, and muscle pain; sometimes goes undetected because no bulls eye rash at stage 1; polyarthralgia

Stage 3: chronic arthritis, encephalitis; lifetime disease

Question 9

Relapsing Fever

Answer 9

2 types

1. Endemic Tick Borne with soft tick; 15 species of Borellia
2. Epidemic Louse Borne: Borellia recurrentis; reservoir are humans

Question 10

Relapsing Fever: Endemic

Answer 10

15 species of Borrelia
occurs at low levels all the time
soft tick
Buzz words: rustic cabin that is in poor condition
relapses occur about 10 times before treatment is sought

Question 11

Relapsing Fever: Epidemic

Answer 11

Borrelia recurrentis
Known as epidemic or louse borne relapsing fever
relapses occur once before treatment sought because many people have it at the time so it is more well known to others
Geography: Ethiopia, Rwanda, Chile
RBCs with spirochetes; big for a bacterium
Dx: microscopy of blood sample; cannot do serology to look for Ab because this organism has antigenic variation
Buzz words: louse born and relapsing fever (recurrent) until they seek treatment

Question 12

Relapsing Fever: Antigenic Variation

Answer 12

The immune system will attack the bacteria to a point when it cannot be detected because the decrease in bacteria, and at this time it increases sweating due to the immune response and also the borrelia are now changing the proteins so the immune system cannot recognize it, then it turns into a cycle
Once they seek tx with antibiotics, this cycle will stop

Question 13

Meningitis: Neonatal vs. Children/Adult Strains

Answer 13

Neonatal: group B Strep (S. agalactiae), E. coli, Listeria monocytogenes

Children/teens/adults: S. pneumoniae, Neisseria meningitides, Haemophilus influenzae type B

Main Virulence Factor: CAPSULE

Question 14

Neonatal Meningitis

Answer 14

Vertical Transmission: from mother
group B Strep aka S. agalactiae: during birth
E. coli: during birth
Listeria: crosses the placenta

Strep agalactiae: Gram positive cocci; catalase negative; can be present in mom’s vaginal flora, so when the baby is being born that is how it can be transferred
E. Coli – from mother’s fecal matter
Listeria crosses the placenta and causes massive damage to the fetus and usually results with miscarriage

Signs and symptoms: nuchal rigiditiy, fever with cold hands and feet, vomiting/refusal to eat, blotchy skin, high pitched moan/cry, blank staring/expression, difficult to wake

Question 15

Streptococcus agalactiae

Answer 15

causes meningitis
Gram positive cocci
Virulence factor: capsule
Normal flora of GI tract and vagina
CAMP: TSA agar with sheep blood; Staph aureus + agalactiae = increases β-hemolysis = positive result; forms an "arrowhead" 

How is it differentiated from Strept pyogenes which is also beta-hemolytic and catalase negative?
S. agalactiae is resistant to bacitracin and S. pyogenes is sensitive

Question 16

E. coli: meningitis

Answer 16

causes meningitis
Normal flora of GI tract
Most E. coli are non-pathogenic
Characteristics: gram negative rod, grows on MacConkey agar, ferments lactose, indole positive
For the strains that cause meningitis, capsule is very important: K antigen

Question 17

Listeria monocytogenes

Answer 17

Gram positive rod, facultative, intracellular pathogen, highly motile
2 types: 1. Flagella for extracellular movement
2. Actin tails from eukaryotic actin (intracellular)

Normally found in soil, vegetation, water and intestinal tract of many animals
Able to grow and multiply at low temps: 1 to 45 degrees C; aka can grow in the refrigerator

Question 18

Listeriosis

Answer 18

Pregnant women: vertical transmission: ingestion; flu-like illness and crosses the placenta
Fetus: transplacental transmission, highly fatal, stillbirth
Newborns: during birth, neonatal meningitis

Transmission: ingestion of contaminated food
Must ingest large numbers to result in infection
Milk- raw/unpasteurized, soft cheeses, cold cuts, hotdogs, raw vegetables, coleslaw
Current major outbreak: cantaloupes; killed several
Incubation period: 11-70 days, ave.31 days

Question 19

Listeria Pathogenesis

Answer 19

Invade M cells like salmonella and EIEC
Escape phagosome
Multiply
Use actin tail for motility
ActA protein forms the actin tail
Infect adjacent cells
Avoids immune system

Question 20

Listeria Dx

Answer 20

Culture: Cold enrichment set at 4 degrees C
Weakly b hemolytic, better with S. aureus
CAMP test: listeria + staph aurues

Question 21

Bacterial Meningitis: Children/Adults

Answer 21

Photophobia, drowsiness/confusion, fitting/seizures, joint pain, nuchal rigidity, headache, fever, and vomiting
Neisseria meningitidis
Haemophilus influenzae type B
S. pneumoniae

Question 22

Neisseria Species

Answer 22

Neisseria
gram negative, diplococci, aerobic, non-motile, fastidious, capnophilic: 5% CO2
N. gonorrhoeae- causes gonorrhea
N. meningitidis- causes meningitis
Buzz words: kidney bean/coffee bean shaped

N. gonorrhoeae vs. meningitides - meningitidis ferments maltose and glucose, but gonorrhoeae ferments ONLY glucose

Question 23

Neisseria Virulence Factors

Answer 23

N. meningitidis: CAPSULE
N. gonorrhoeae: pili most important for antigenic variation
Pili, Por proteins (outer membrane), Opa proteins, LOS (instead of LPS), Rmp proteins, IgA protease, and capsule

Question 24

N. meningitidis Infections

Answer 24

Low prevalence, high mortality
If untreated, mortality rate close to 100%, with treatment 10%
Approximately 20% of the population are healthy carriers
Seasonal: winter
Transmission: Respiratory droplets
Viral meningitis is more common and less deadly
Bacterial meningitis is less common and more deadly
Need to know viral vs. bacterial so you know how to treat the patient appropriately
The vaccine does not cover type B… most colleges require the vaccine

Question 25

Pathogenesis of Neisseria

Answer 25

transmission, attach and invade mucosal cells (via pili, PorA, PorB, Opa, capsule), multiply within mucosal cells, move into subepithelial space, LOS stimulates TNF alpha symptoms like fever

Question 26

N. meningitidis High Risk Groups and Symptoms

Answer 26

High Risk Groups: infants 6months-2 years because under 6 months protected by maternal antibodies, army recruits, college students living in residence halls, complement deficiency (immunodecificent)

Symptoms: sudden onset of severe headache, fever, neck stiffness, irritability, photophobia, malaise, nausea/ vomiting

Question 27

Meningococcemia

Answer 27

Invasion of the bloodstream, sepsis, thrombosis of small blood vessels
Symptoms: fever, chills, arthralgia, muscle pain, petechial rash
very similar to gonoccemia, therefore must do additional testing (maltose vs. glucose fermentation)

Question 28

N. meningitidis Dx

Answer 28

Diagnosis: spinal tap, Gram stain of CSF
Meningococcemia: Gram stain of blood
Culture on: Thayer-Martin agar (chocolate agar with antibiotic on it so nothing else will grow other than Neisseria)
Chocolate: blood agar that has been heated/lysed before plated out and allowed to solidify

Question 29

Meningitis vaccines

Answer 29

2 vaccines:

1. Meningococcal capsular polysaccharide vaccine
   A, C, Y, & W135
   Does not work in children < 2 yrs old or for type B strain
2. Meningococcal conjugate vaccine
   Recommended for: college students, army recruits, splenectomy, travelers

Question 30

Haemophilus influenzae

Answer 30

causes meningitis in adults/children
Characteristics: gram negative short fat rod, normal flora of the URT, capsule or no capsule (must have a capsule to cause meningitis), adhesins, endotoxin

1. Has capsule: Serotypes a-f, Haemophilus influenzae type b
   Hib: 1987 vaccine available - for type B strain
   causes: meningitis, epiglottitis
   Unvaccinated children- at risk
2. No capsule: non-typeable, otitis media (inflammation of middle ear), sinusitis, bronchitis, pneumonia

Question 31

Haemophilus influenza Dx

Answer 31

Microscopy/Gram stain
Culture: fastidious
Does not grown on blood agar or MacConkey agar
Chocolate agar only because it requires X (heme) factor and V (NAD)factor that are readily available from the lysed red blood cells on the chocolate agar

Question 32

Streptococcus pneumoniae

Answer 32

causes meningitis and pneumonia
Characteristics of bacteria: also known as pneumococcus, cause typical pneumonia, gram positive in pairs or chains, alpha hemolytic on blood agar, CAPSULE (making meningitis infection possible), adhesin, and IgA protease
Transmitted by respiratory droplets
Part of the normal flora of URT
5-75% incidence of carriage
Lab Tests: Optochin sensitive

Question 33

UTIs: signs/symptoms + causative agents

Answer 33

Signs and symptoms: dysuria- painful urination, urgency, increased frequency, pyuria- pus/WBCs in the urine, and hematuria*- blood in the urine

Causative agents: E.coli, staphylococcus epi and sapro, and proteus

Question 34

E. coli: UTIs

Answer 34

1 cause of Urinary tract infections

Endogenous infection
Colon urethra ascends into bladder
UPEC: uropathogenic E. coli
Virulence factor: Pap (pyelonephritis associated pili) pili for adherence

If not treatment for UTI, you can get kidney infection= more serious; steps:
Contamination of periurethral area with E. coli from the bowel, adherence to uroepithelium via fimbriae, invasion, apoptosis of bladder epithelium, influx of PMNs, E. coli selected with high CFU and low O2, E. coli ascends to kidney via ureters and binds to renal tubular epithelial cells, cytokines induced (inflammation), haemolysin damages the epithelium, glomeruli are damaged, E. coli crosses the barrier to initiate bacteremia (sepsis)

Question 35

Staphylococci (CoNS) and UTIs

Answer 35

Gram(+) cocci, catalase(+), coagulase(-); cause UTIs

Staphylococcus epidermidis- normal flora, novobiocin sensitive, ability to adhere to plastic, opportunistic infections of catheters

Staphylococcus saprophyticus- can colonize vaginal tract, novobiocin resistant, UTIs in young, sexually active females

Question 36

Flow Chart for Staph Species

Answer 36

Catalase + = staph species
Coagulase test: + is staph aureus; - is other staph species
Novobiocin: resistance (growth) is S. saprophyticus; sensitive (no growth) is S. epidermidis

Question 37

Proteus

Answer 37

2 species: 1. Proteus mirabilis* (most common) 2.Proteus vulgaris
Both species cause UTI
Swarming motility
Virulence factor: urease
Urea that breaks down into ammonia + CO2
Increases urine pH
Formation of kidney stones
Buzz word: swarming/ swarming motility

Question 38

Kidney Stones

Answer 38

created by Proteus
Crystal aggregations of minerals found within urine
Vary from grain of sand to size of golf ball
Struvite Kidney Stones
Only type of stone known to derive from bacteria
Urease: Urea breaks down into ammonia + CO2
Crystal formation occurs: golf ball size