Cornyebacteria and Actinomycetes

Question 1

Coryneform

Answer 1

G+
irregular rods
high G-C content
{coryne, arcano,brevi, rthoia, tropheryma}

Question 2

Corynebacteria

Answer 2

aerobic/facultative ana
chinese letters
short-chain mycolic (not acid-fast)
metachormatic granules (inorganic phosphates that act as E storage)
normally opportunisitic

Question 3

C. diphtheriae sx

Answer 3

diffculty swallowing, epiglottitis, lung infiltrates, exudate, flesh brown pseudomembrane over throat, loss of appetite, hoarseness, URT mucus membranes

2-3d hallmark of respiratory: firm, fleshy grey pseudomembrane – bleeds following attempts to remove/dislodge

fatal airway obstruction
Bull neck

complications: myocarditis, polyneuropathies

Question 4

C diphtheriae transmission

Answer 4

P2P, oral/respiratory

Respiratory: 1˚ pediatric disease

Cutaneous: common in tropical areas

Question 5

C. diphtheriae virulence factors

Answer 5

Diptheria toxin:
-AB toxin
-heparin-binding epidermal growth factor
-ADP ribosylation –> EF-2 inhibition, accumulation of cells –> pseudomembrane
(necrotic epithelium embedded w/fibrin and red/white cells
*toxin encoded by lysogenic bacteriophage
*strains w/o phage can still give septicemia, endocarditis

Question 6

C. diphtheriae dx

Answer 6

More of clinical presentation

• vacc hx, endemic region visit
• pharyngeal characteristics

Cysteine-tellurite blood agar or loeffler’s agar
Elek’s text - antitoxin on paper
PCR - presence of tox gene

Question 7

C. diphtheriae tx

Answer 7

Antitoxin (early admin.)
-equine serum, make sure no sensitivity to serum sickness

ensure airway clear – Abx: pen, erythro to maintain clearance/prevent carrier status

antimicrobial prophylaxis for close contact (booster vaccinations)

Question 8

C. diphtheriae vacc

Answer 8

DTaP: combined vacc, 4 doses

Tdap: booster

• reduced [diphtheria & pertussis]
• every 10 years

Question 9

C. jeikeium

Answer 9

NO PHAGE
opportunistic
hematologic disorders / intravascular catheters
skin of hosp pts 
V resistant to abx

Question 10

C. urealyticum

Answer 10

NO PHAGE
uncommon in healthy people
urease producer
strutive calculi/renal stones

@risk: immunosupp, GU, urologic procedures, Abx therapy

resistant to Abx

Question 11

C. amycolatum

Answer 11

NO PHAGE
found on skin not in oropharynx
opportunistic
misidenitified
resistant to Abx

Question 12

C. ulcerans

Answer 12

Can carry diphtheria gene (PHAGE)

indistinguishable from diphtheria

Question 13

C. pseudotuberculosis

Answer 13

Can carry diphtheria gene (PHAGE)

rare

Question 14

Arcanobacterium

Answer 14

G+
irregular rod
colonizer/pathogen
pharyngitis, wound infections (polymicrobial), endocarditis, septicemia

Tx: penicillin, erythro

Question 15

Brevibacterium

Answer 15

G+ 
rod
skin colonizer
cheeselike odor
maldorous feet 
septicemia, osteromyleitis, foreign body infxn

rod-shaped when young, cocci when old

Tx: (b-lac resist) Vanco, tetra, genta

Question 16

Rothia mucilaginosa

Answer 16

G+ coccoid (not rod)
Cluster growth
Mucoid/sticky –> biofilms
Unpredictable vs abx

Question 17

Tropheryma whippelii

Answer 17

G+ rod
Foamy macrophages
acid-schiff positive
obligate intracellular parasite
Whipple disease
-old men, caucasians
GI disorder (malabsorption, wt loss, diarrhea)
fatty acid deposits in intestine and mesenteric lymphatic tissue
arthalgia

disordered IR to persistent bacteria

Question 18

Tropheryma whippelii dx

Answer 18

Intestinal biopsy
PAS + macropage inclusions
IHC staining
PCR confirmations

Question 19

Tropheryma whippelii tx

Answer 19

2wk: parenteral pen/strepto
1yr: bactrim

Question 20

Proprionibacterium

Answer 20

G+ rods
non-motile
Anaerobic (aerotolerant)
ACNE: p. acne and p, propionicum
Opportunisitc infections
Endodontic abscesses, lacrimal canaliculitis

Question 21

Proprionibacterium microbio/tx

Answer 21

infect/block sebaceous follicle
increased sebum and androgen prod
leuko migration –> inflammation

Topical Abx: erythro, clinda, tetra
Benzoyl peroxide: increased skin turnover

Question 22

Nocardia gen/sx

Answer 22

Medium chain mycolic acid (spotty stain)
partially acid-fast
beading pattern in gram stain
external environment-exogenous
immunocompromised*
filamentous growth

pulmonary, brain (pts w/T cell def), cutaneous, subQ

*mycetoma-anaerobic actinomycetes or fungi

Question 23

Actinomyces

Answer 23

no mycolic acids
not acid-fast
uniform gram stain
mucous membrane-endogenous
molar tooth colonies
sulfur granules in plate-cultured isolates

Question 24

Nocardia pathogenesis

Answer 24

Live in phago for quite a while

cord factor: prevents phagolyso fusion

prevent acidification

protected from O metabolites (catalase/superoxidase mutase)

avoid acid-phosphatase-mediated kiling (host enzyme is utilized as nutrient source)

Question 25

Nocardia Dx/Tx

Answer 25

Staining (sputum, abscess, CSF)
Will grow on most media
PCR

Tx: bactrim for local, amikacin + carbapenem for systemic

Question 26

Actinomyces Sx

Answer 26

URT, GI, female GU (NOT on skin)
Poor oral hygiene, aspiration into lungs, abdominal infections

1. cervicofacial: lumpy jaw*
2. thoracic: pulmonary infiltrate, farmer’s lung* (T3 hypersensitivity rxn)
3. abdomen/pelvis: bowel surgeries
4. cutaneous/subQ
5. brain abscesses

Question 27

Actinomyces Dx/Tx

Answer 27

Sulfur granules crushed and microscopically examined

Culture (slow) fastidious

PCR

Tx: drain abscess, Pen 6mo-1yr (resistant to a ton of shit)