ch. 20 Serological and Molecular Detection of Bacterial Infections

Question 1

No benefit or harm to either organism

Answer 1

Commensal

Question 2

Staphylococcus epidermidis uses dead skin cells as nutrients. this is an example of what

Answer 2

Commensal

Question 3

Both host and microbes benefit. ex: Gut bacteria (E.coli, H. pylori, Candida albicans, Lactobacillus acidophilus

Answer 3

Mutualistic

Question 4

Microbes cause harm to the host
* Fleas, tapeworms

Answer 4

parasitic

Question 5

Organism’s ability to establish an infection

Answer 5

infectivity

Question 6

Ability of an organism to cause disease
* May be increased by virulence factors

Answer 6

pathogenicity

Question 7

Extent of pathology caused by an organism when
it infects a host

Answer 7

virulence

Question 8

Detect antibodies to bacterial antigens

Answer 8

serological testing

Question 9

The acute sample should be what and run with the
convalescent specimen to eliminate differences in titer
due to technical variations.

Answer 9

frozen

Question 10

To determine a past exposure to an organism, what would results look like

Answer 10

IgM–, IgG+

Question 11

infection indicated by presence of IgM, a
high IgG titer, or a fourfold rise in antibody titer
between acute and convalescent samples

Answer 11

acute or current infection

Question 12

is a single titer result meaningful

Answer 12

no, bc there is no other results to compare

Question 13

A fourfold increase in titer from acute to convalescent
specimen is

Answer 13

diagnostic

Question 14

IgM antibody is a sign of what

Answer 14

recent infection

Question 15

disadvantages of serological testing

Answer 15

Delay between start of infection and production
of antibodies

Question 16

Gram-negative rod that lacks a cell wall

Answer 16

Mycoplasma pneumoniae

Question 17

Cannot be treated with penicillin (because it doesn’t have a cell wall)

Answer 17

Mycoplasma pneumoniae

Question 18

Spread by respiratory droplets “Community acquired pneumonia”
▪ Leading cause of respiratory infections worldwide

Answer 18

Mycoplasma pneumoniae

Question 19

Dermatological Manifestations of Mycoplasma Pneumoniae

Answer 19

Raynaud syndrome
* Stevens-Johnson syndrome

Question 20

would lab dx test would you perform to dx mycoplasma pneumoniae?

Answer 20

M. pneumonia antibody test

Question 21

what is the gold standard for testing mycoplasma pneumonia but rarely performed?

Answer 21

culture

Question 22

what is present in about 50% of patients with M. pneumoniae
but not specific for the infection

Answer 22

cold agglutinins

Question 23

cold agglutinins may be found in other infections such as

Answer 23

ebv, mono, and anti-i antibody

Question 24

molecular method used to test M. Pneumoniae

Answer 24

PCR

Question 25

what does PCR stand for?

Answer 25

Polymerase Chain Reaction

Question 26

Molecular testing involves copying parts of the DNA, tagging it and replicating it multiple times and amplifying its single/

Answer 26

PCR testing

Question 27

May follow strep infection of the skin or pharynx * Deposits of immune complexes containing streptococcal antigens in glomeruli

Answer 27

Poststreptococcal glomerulonephritis

Question 28

Develops 1 to 3 weeks after pharyngitis or tonsillitis in 2% to 3% of infected individuals * Most likely caused by immune responses to streptococcal antigens that cross-react with human heart tissue

Answer 28

Acute rheumatic fever

Question 29

involved preparing serial dilutions of patient’s serum to which a measured amount of streptolysin O reagent was added; incubated; reagent RBCs added as an indicator; look for hemolysis.

Answer 29

Classic hemolytic method ASO titers

Question 30

Nephelometric methods currently used that measure light scatter produced by immune complexes containing streptolysin antigen

Answer 30

serological detection of Antistreptolysin O (ASO

Question 31

Titer elevated in 85% of patients with acute rheumatic fever. what titer is this?

Answer 31

ASO titer

Question 32

Produced by both rheumatic fever and impetigo patients * Tested by EIA and nephelometric methods

Answer 32

Anti-DNase B

Question 33

Detects antibodies to five streptococcal products: * ASO * Anti-hyaluronidase (AHase) * Anti-streptokinase (ASKase) * Anti-nicotinamide-adenine dinucleotide (anti-NAD) * Anti-DNase B

Answer 33

Streptozyme test

Question 34

Obligate intracellular gram-negative coccobacilli bacteria (grow in tissue culture)

Answer 34

Rickettsial Infections

Question 35

Organisms transmitted by arthropods (ticks, mites, lice, or fleas) through biting after feeding on an infected animal (vector are arthropods) ▪ Organisms spread via the lymphatic & circulatory systems

Answer 35

Rickettsial Infections

Question 36

Caused by Rickettsia rickettsii

Answer 36

RMSF

Question 37

Causes endothelial skin damage

Answer 37

Rickettsia rickettsii (RMSF)

Question 38

Rashes starts on the hands and soles of the feet, then trunk. death occurs how many days after onset symptoms?

Answer 38

7-10 days

Question 39

best method for testing for RMSF?

Answer 39

testing antibodies,Weil-Felix test (historic test)

Question 40

most common bacterial std

Answer 40

Chlamydia trachomatis

Question 41

True bacteria ▪ Obligate intracellular (non-culturable)

Answer 41

Chlamydia trachomatis

Question 42

when testing for Chlamydia trachomatis what method is used?

Answer 42

PCR or NAAT(Nucleic acid amplification test)