L11- RTI III Flashcards
Streptococcus properties:
- Gram(+/-)
- (cocci/rods)
- catalase(+/-), but does contain (4)
- (non-/motile)
- most species are (obligate aerobes / obligate anaerobes / facultative anaerobes)
Gram+ cocci, catalase- but has Superoxide Dismutase (=> aerotolerant), non-motile, facultative anaerobes
Strep. spp. are divided into groups through (1) agar, but are classified by (2)
1- blood agar (sheep) => α β γ
2- polysaccharide Ag in cell wall => Lancefield groupings
GAS polysaccharide capsule is made out of…..
hyaluronic acid
S. pneumoniae capsule has the (1) property which is used for (2)
1- quellung reaction: swollen capsule in presence of antiserum
2- serotyping S. pneumoniae
S. pyogenes:
- blood agar result is (1), it is due to presence of (2)
- (3) is an important sensitivity/resistance property
- (4) is an additional and notable positive test result
1- β-hemolytic
2- Streptolysin S
3- Bacitracin sensitivity
4- PYR+ (pyrolidonyl arylamidase hydrolysis of L-pyrolidonyl-β-naphthylamide)
S. pneumoniae:
- blood agar result is (1)
- (2) is an important sensitivity/resistance property
1- α-hemolytic
2- optochin sensitive
S. pyogenes:
- pyogen = (1), because of (2) in the bacterium
- (3) reservoir
- (4) transmission
1- induces pus formation
2- leukocidin
3- human throat
4- direct contact, respiratory droplets
list the syndromes caused by S. pyogenes
- pharyngitis (strep throat)
- skin infections (impetigo, etc)
- soft tissue infections
- rheumatic fever
- glomerulonephritis
what properties of Strep. spp. contributed to the varying virulence factors between species
- transduction-mediated gene transfer (bacteriophages)
- transformation (DNA uptake from environment)
S. pyogenes / GAS virulence factors:
- (1) and (2) are cell wall carbohydrate and protein respectively (indicate if they are for group/type)
- (3) for phagocytosis evasion
- (4) adherence / invasion
- (5) toxins
1- A antigen (group specific- same for all GAS)
2- M protein (type specific- serotype)
3- capsule, C5a peptide + (M/M-like proteins, F protein, Lipoteichoic acid)
4- M proteins, F protein, Lipoteichoic acid
5- Streptolysin S (RBCs), Streptolysin O (WBCs) + (SPE/strep. pyrogenic exotoxins, DNAse)
describe the Sxs of GAS / Strep. pharyngitis
(suppurative GAS disease)
- inflamed pharynx with exudates
- anterior cervical lymphadenopathy
describe the Sxs of Scarlet Fever
(suppurative GAS disease)
-via GAS, sequela to Pharyngitis
- diffuse erythematous rash: starts on trunk/chest –> moves to extremities
- strawberry tongue
what are two non-suppurative diseases stemming from GAS
- Rheumatic Fever: type II sensitivity rxn
- Acute Glomerulonephritis:
Rheumatic Fevers is caused by (1), proceeding (2). It results from a (3) type reaction. It is described symptomatically with the following: (4).
1- GAS
2- Strep. pharyngitis (2-4 wks)
3- type II hypersensitivity
4- endocarditis, polyarthritis, subcutaneous nodules, chorea (JONES criteria)
Acute Glomerulonephritis can result after (1) infection of the (2). It presents symptomatically with (3).
1- GAS
2- pharyngitis (7-10 days) or impetigo (3 wks)
3- edema, HTN, hematuria, proteinuria
Corynebacterium properties:
- Gram(+/-)
- (cocci/rods)
- (non-/spore forming)
- (aerobic/anaerobic)
- (5) color and shape appearance on slide
Gram+ rods, non-spore forming, aerobic
5:
- gray-to-black colonies
- shape is pleomorphic called ‘club-shaped’ / V/L shaped / ‘chinese letter arrangement’ —- this is due to snapping cell division (incomplete membrane separation)
The main corynebacterium species that cause infection is (1), while many other species are (2)
1- C. diphtheriae
2- non-pathogenic members of flora in pharynx, nasopharynx, skin
C. diphtheriae appears as (1) color in slides due to (2) produced on (3) mediums after staining the sample metachromatically.
1- gray-to-black
2- granules / volutin
3- Loeffler’s coagulated serum medium
The most critical virulence factor that may be present in C. diphtheriae is…..
(toxin producing strains)
-β-prophage carries genes for toxin (lysogeny, β-corynephage)
Note- phage from toxin-diphtheria infected Pt can infect / transmit to non-toxin diphtheria infected Pt
**Mobile gene elements
Respiratory Diphtheria:
- (1) regular Sxs
- (2) hallmark Sxs, include what it can lead too
- (3) severe manifestations
1- (sudden onset) exudative pharyngitis, sore throat, fever, malaise, dysphagia
2- i) thick pseudomembrane (dead cells / bacteria) –> can possibly cause respiratory obstruction; ii) bull neck appearance
3- myocarditis, recurrent laryngeal nerve palsy
Cutaneous Diphtheria clinical presentation
- papule on skin progresses to healing ulcer
- systemic signs can develop
C. diphtheria can be dangerous in (1) areas because of (2)
1- endemic in some subtropical and tropical countries (+ underdeveloped countries with poor health infrastructure)
2- diphtheria toxoid vaccine is apart of DTaP
C. diphtheria is a unique organism because it is not (1) to yield systemic symptoms, instead (2) will cause systemic manifestations. (2) can be acquired in C. diphtheria via (3). (2) will specifically cause (4) and (5).
1- non-invasive, does not enter bloodstream
2- diphtheria exotoxin
3- bacteriophage (lysogenic conversion)
4- inflammation and formation of pseudomembrane
5- damage to organs
list the medias for C. diphtheria
- Cysteine-Tellurite blood agar (CTBA)
- Tinsdale medium
- Colistin-nalidixic agar (CAN)
what are the characteristics needed for Dx of C. diphtheria infection
(culture on selective media)
-characteristic grey-to-black colonies with brown halo
1) tellurite reductase +, cystinase +
2) urease -, pyrazinamidase -
3) toxingenicity test: ELEK, PCR
describe the ELEK test and what it is used for
Test for toxigenicity, specifically for C. diphtheria
1) incubation culture with a streak of known non-toxigenic strain and unknown, suspected toxigenic strain
2) place filter paper with anti-toxin
3)
- Pos (toxigenic): lines of precipitin (area of no growth)
- Neg (non-toxigenic): grows the same as the known non-toxigenic strain
______ are common squeal of infection
- sinusitis
- acute otitis media (AOM)
Sinusitis and AOM are mostly caused by (1) pathogens, including (2).
The second most common pathogens are (3) including (4).
1- viruses
2- rhinovirus, adenovirus, coronavirus (same as rhinitis)
3- bacteria
4- Strep. pneumoniae, Haemophilus influenza, Moraxella catarrhalis
describe the Sxs of sinusitis
(inflammation of any of the four pairs of sinuses)
- bad breath / loss of smell
- fatigue, fever, HA
- pressure-like pain with facial tenderness + pain behind eyes, toothache
- nasal congestion and discharge
- cough (worse at night)
- sore throat, postnasal drip
AOM Sxs:
(1) common Sxs
(2) describe the TM
(3) neonatal Sxs
1- fever, ear pain (ear tugging), hearing loss, ear stuffiness
2- (tympanic membrane) immobile, inflamed, perforated and or bulging of TM, ear discharge
3- irritability, feeding difficulties
list the syndromes caused by Haemophilus influenzae
otitis media, sinusitis, pneumonia, epiglottitis, meningitis, COPD acute exacerbation
(1) is the most common cause of epiglottitis, which is described as (2). (3) are other epiglottitis associated microbes.
1- haemophilus influenzae
2- epiglottic and supraglottic swelling / inflammation
3- C. diphtheria, N. meningitis
Note- 90% of epiglottitis is caused by bacteria
Haemophilus influenzae:
- (small/large)
- (2) shape [cocci/bacillus]
- Gram(+/-)
- coagulase(+/-)
- catalase(+/-)
small Gram- coccobacilli with pleomorphic shape (shape is able to change / is variable) coagulase- catalase+
describe the 2 types of Haemophilus influenzae
Non-Typeable / Non-Encapsulated:
- colonizes in URT of children / adults
- causes otits media, sinusitis, COPD exacerbations
Typeable / Capsulated:
- serotyped a –> f
- type b has invasive disease, Hib does have a vaccine
- other types are apart of normal microbiota
Haemophilus influenzae virulence factors:
- (1) and (2) are for adhesion
- (3) makes up capsule
- (4) is a toxin
- (5) is a useful protease
1- pili
2- non-pilus adhesins: P-2 outer membrane protein
3- PRP (polyribose ribitol phosphate)
4- LPS endotoxin impairs ciliary function
5- IgA proteases, >30 types
describe the requirements for Haemophilus influenzae culture (and the appearance)
chocolate agar (heated blood agar) with the following factors:
- X growth factor: acts as **hemin
- V growth factor: **NAD (nicotinamide adenine dinnucleotide)
**colonies appear large, round, opaque
Haemophilus influenzae Epiglottitis clinical features / common Sxs
fever, sore throat, dys-/odyno-phagia, stridor, restlessness, drooling, hoarseness, muffled voice, tripod position
describe tripod position sign in Haemophilus influenzae Epiglottitis
trunk leaning forward
neck hyper-extended
chin thrust forward
describe radiological evidence for Haemophilus influenzae Epiglottitis
enlarged epiglottis = ‘thumb sign’
aryepiglottic folds thickening
