Bacteriology- Bacillus, Clostridium, Diphtheriae Flashcards
Bacillus anthracis is gram ?
positive
Bacillus anthracis is bioterrorism category?
A
Capsule of B. anthracis is made of?
Polypeptide (Glutamic acid)
Anthrax toxin includes
- Lethal factor- causes necrosis
- Edema factor- increases cAMP
- Protective antigen- for vaccine prep
Hide porter’s disease
Cutaneous anthrax
Eschar
Malignant pustule
Wool sorter disease
Pulmonary anthrax
Mediastinal widening
Other types of anthrax
cerebral, intestinal
Lab diagnosis of anthrax
Bamboo stick/ box car appearance on microscopy
Culture: PLET (polymyxin, lyzozyme, EDTA, Thallus acetate)– Frosted glass appearance on naked eye; microscopy- medusa head appearance
ELISA/ PCR
Tx for anthrax
Cirpofloxacin/ Doxycycline
For meningitis- 60 days antibiotics– Ciprofloxacin, Meropenem, Clindamycin
If systemic involvement- Monoclonal Ab added + antitoxin
Virulence factor for B. cereus
Lecithinase– can cause food poisoning
B. cereus food poisoning occurs d/t consumption of
Reheated starch rich food (eg. chinese fried rice)
Early emetic type of B. cereus poisoning can mimic
Delayed diarrhoeal type of B. cereus poisoning can mimic
Staph Enterotoxin
E.coli Labile toxin
B. cereus causes
Food poisoning
Pan ophthalmitis
Selective media for B cereus
MYPPA, PEMBA
Difference between the two is MYPPA contains Phenol red as stain, PEMBA contains Bromothymol blue
Culture characteristics of B cereus
Opalascent colonies
Tx for cereus
Ciprofloxacin, Vancomycin
Clostridium difficile causes
Antibiotic asso pseudomembranous enterocolitis
Toxins of C. difficile
Toxin A- enterotoxin
Toxin B- Cytotoxin
Which antibiotics causes pseudomembranous colitis?
Aminopenicillins, penicillins, cephalosporins
When is the onset of pseudomembranous colitis?
5th day of administration of antibiotics
Selective media for difficile
CCFA agar, CCYA agar
Toxin of difficile can be demonstrated by ____ and toxin gene can be demonstrated by ____
ELISA
RT-PCR
DOC for difficile infection
Vancomycin
If failed– Fidaxomycin
Toxin of C. botulinum
Decreases release of ACh in NM junction
Types of Botulism
Wound botulism- spore from environment
Food borne botulism- toxin- (canned food)
Infant botulism- spore- honey
Clinical features of botulism
Diplopia
Dysarthria
Descending paralysis
Dysphagia
Decreased DTR
Flaccid paralysis
In babies– Floppy baby syndrome
Tx for botulism, perfringens and tetani
Early stage: Penicillin
Late stage: Antitoxin
Clostridium tetani
1. Shape
2. Motility
3. Characteristic in medium
4. Toxin
- Drumstick
- Stately
- Swarming on blood agar
- Tetanospasmin, Tetanolysin
Tetanospasmin MOA
Inhibit release of GABA and Glycine in neuromuscular junction (presynaptically)
Prevents fusion of SNARE proteins– SNAP 25, Synaptobrevin, Syntaxin
So causes Spastic paralysis
Clostridium perfringens
1. Motility
2. Capsule characteristics
- Non motile
- Antiphagocytic, Virulent, forms mucoid colonies, Serotypes (5 )
Toxins produced by C. perfringens
Alpha, Beta, Gamma, Theta
Alpha toxin has Lecithinase
Diseases caused by Perfingens
Gas gangrene
Necrotizing fasciitis
Necrotizing enterocolitis
Necrotizing enteritis
Caused by Serotype A
Pigbel, Necrotizing enterocolitis caused by serotype C
Lab diagnosis of perfringens
Target hemolysis- inner ring d/t theta toxin, outer- alpha toxin
Reverse CAMP test
Naegler’s reaction
Robertson cooked meat broth
Stormy clot on litmus milk
Naegler’s reaction has ____ medium. The area with no antitoxin, _____ colonies are produced due to ____ toxin having ___ activity
egg based
opalescent
alpha
lecithinase
Toxins that decrease protein synthesis
Diphtheriae toxin, Exotoxin A of pseudomonas– ADP phosphorylation of elongation factor 2
Shiga toxin of Shigella and Shiga like toxin of E. coli– inhibit 60S ribosome
Diphtheriae toxin depends on what mineral?
Iron
How is diphtheriae toxin converted to vaccine?
Toxoid form is made into vaccine ; by formalin + acidic pH
C. diphtheriae shows ___ division
Snapping
Media used for early diagnosis for diphtheria
Best media for diphtheria diagnosis
Early- Enriched media- Loeffler serum slope (8 hrs)
Best- Selective media- K tellurite agar, Tinsdale medium (48 hrs)
What test is employed to check for toxigenicity of diphtheria bacteria?
Elek’s gel precipitation test
In center- filter paper with antitoxin. If precipitin line forms– + for toxigenic strain
Schick test
To test for susceptibility of a person to Diphtheria
On injection of antigen, if rash develops– susceptible
- Daisy head colonies by?
- Frog head colonies by?
- Poached egg colonies by?
- C. gravis
- C. intermedius
- C. mitis
Lipophillic Corynebacterium species
C. Jeikeium
C. urealyticum
Corynebacterium species seen in prosthetic valve endocarditis
C. jeikeium
Non lipophillic Corynebacterium species
C. ulcerans
C. minutissimum
C. pseudotuberculosis
Struvite stones show which Corynebacterium species
C. urealyticum
Coral fluorescence on wood lamp examination is shown by
C. minutissimum
Spores of clostridium vs bacillus
Bacillus have non bulging spores
Clostridium has bulging spores
MC form of anthrax that is asso with bioterrorism
Pulmonary anthrax
Serology of B. anthrax is tested by
Ascoli’s ring thermoprecipitin test
Culture appearance of B. anthracis
Frosted glass appearance
Beaten egg appearance
Comet tail appearance
String of pearls app on Penicillin agar
Inverted tree app on gelatin swab is shown by
B. anthracis
Fir tree app on gelatin swab shown by
C. tetani
Turnip/ napiform app on gelatin stab shown by
V. cholerae
Emetic type of Cereus infection MOA
Increased cGMP
Diarrhoeal type of cereus infection MOA
Increases cAMP
Spore of B. cereus is present
centrally
Tennis racket shaped spore
Clostridium tertium
Non motile clostridium
C. tetani
C. perfringens
Capsulated clostridium
C. perfringens
C. butyricum
Which organism shows citron bodies
C. septicum
Pigbel occurs d/t
C. perfringens
It is pork + sweet potatoes
In Robertson cooked meat broth, what reaction does C. perfringens give?
Saccharolytic reaction (red/pink)
First muscle to be affected by C. tetani
Masseter
On Robertson cooked meat broth, appearance of C. tetani
Black, proteolytic reaction