M5: Bacteriology (Part 2: Non-Spore forming Gram-Positive Bacilli)

Corynebacterium diphtheriae

Have a “club-shaped” appearance and “beaded” appearance that form metachromatic granules (volutin – phosphate)

Corynebacterium diphtheriae

Arranged in palisades or in V- or L-shaped formation

Corynebacterium diphtheriae

Brown-black/Black colonies in Tellurite agar

Corynebacterium diphtheriae

Characterized by Chinese letter characters in Loeffler’s serum media

Corynebacterium diphtheriae

Has 4 biotypes – gravis, mitis, intermedius, and belfanti

Corynebacterium diphtheriae

Aerobic, pleomorphic

gravis, mitis, intermedius, and belfanti

Corynebacterium diphtheriae has 4 biotypes

A (binding) and B (toxic activity)

Diphtheria toxin is a polypeptide with 2 fragments:

upper respiratory tract

Both toxigenic and non-toxigenic C. diphtheriae resides in the __________

bacteriophage (virus-infecting bacteria)

Acquisition of diphtheria toxin happens in the presence of a _________

Betaphage

encodes the tox gene of the diphtheria toxin

Respiratory diphtheria

Acquired through airborne droplet transmission

Respiratory diphtheria

Sore throat and low-grade fever initially develop

Respiratory diphtheria

Most prominent sign is the thick, gray, adherent pseudomembrane over the tonsils and throat

Respiratory diphtheria

Extends down to the larynx and trachea – obstructs airways

Respiratory diphtheria

Enlargement of regional lymph nodes and marked edema in the neck and can cause a bull neck

pseudomembrane

Most prominent sign of respiratory diphtheria is the thick, gray, adherent ___________ over the tonsils and throat

bull neck

Enlargement of regional lymph nodes and marked edema in the neck and can cause a _________ (respiratory diptheria)

Cutaneous wound/skin diphtheria

Characterized by a membrane on an infected wound

Cutaneous wound/skin diphtheria

A membrane may be form on an infected wound that fails to heal

Cutaneous wound/skin diphtheria

Can still establish an infection

Myocarditis

_______________ accompanied by arrhythmias (irregular beating of the heart) and circulatory collapse

Nerve weakness or paralysis

Other complications of Corynebacterium Diphtheria

Complication on liver and kidneys

Other complications of Corynebacterium Diphtheria

Diphtheria antitoxin (IM and IV)

Treatment of Corynebacterium Diphtheria

Antimicrobial drugs (penicillin and macrolides like erythromycin)

Treatment of Corynebacterium Diphtheria

administration of diphtheria toxoid

Prevention of Corynebacterium Diphtheria

administration of diphtheria toxoid

Inject diphtheria to the horse → create antitoxins → harvest and purify

Schick test

detects immunity to diphtheria

Schick test

Done by ID injection of 0.1 mL of diphtheria toxin

Schick test

Check for reaction after 4 to 7 days

Inflammation as a response to Schick test

indicates no anti-toxin

No Inflammation as a response to Schick test

has anti-toxin

Listeria monocytogenes

Psychotroph

Listeria monocytogenes

Exhibits a tumbling end over end motility at 22 – 28°C but not at 37°C

Listeria monocytogenes

There are 13 serovars based on O and H antigens

Listeria monocytogenes

Exhibit B-hemolysis on blood agar plate (complete hemolysis), esculin hydrolysis positive, and motile

O antigen

found on cell wall, somatic

H antigen

flagellar

B-hemolysis

Listeria monocytogenes exhibit ______ on blood agar plate (complete hemolysis), esculin hydrolysis positive, and motile

unpasteurized food like cheese

Transmission is via GI tract in Listeria monocytogenes

Internalins A and B

surface proteins interacting with E-cadherin, a receptor on epithelial cells, promoting phagocytosis into the epithelial cells (Listeria monocytogenes)

Lysteriolysin O

after phagocytosis, low pH activates the bacterium to produce lysteriolysin; lyses the membrane of phagolysosome and allows the listeriae to escape into the cytoplasm

Act A protein

propels the bacteria to the host cell membrane

forms elongated protrusions

forms elongated protrusions

Early onset syndrome, Late onset syndrome

There are two forms of perinatal human listeriosis

granulomatosis infatiseptica

Early onset syndrome

Early onset syndrome

characterized by neonatal sepsis, pustular lesions, and granulomas

Late onset syndrome

development of meningitis between birth and 3rd week of life

Gastroenteritis

may no become ill or may develop a mild, self-limiting febrile gastroenteritis lasting 1 – 3 days (Listeria monocytogenes)

1 – 3 days

may no become ill or may develop a mild, self-limiting febrile gastroenteritis lasting _________ (Listeria monocytogenes)

Ampicillin with or without gentamicin (aminoglycoside antibiotic)

Treatment for Listeria monocytogenes: meningitis and sepsis

Trimethoprim-sulfamethoxazole

Treatment for Listeria monocytogenes: CNS infection for patients allergic to penicillin

Erysipelothrix rusopathiae

Gram-positive bacillus that produces small, transparent glistening colonies

Erysipelothrix rusopathiae

Short chains or long non-branching filaments

Erysipelothrix rusopathiae

Alpha-hemolytic in blood agar

erysipeloid.

The most common E. rusopathiae infection in humans is called ___________

seal finger and whale finger

Usually occurs on the fingers by direct inoculation at the site of a cut or abrasion (has been called ________)

erysipeloid

Usually occurs on the fingers by direct inoculation at the site of a cut or abrasion (has been called seal finger and whale finger)

erysipeloid

Can be resolve without treatment after 3 – 4 weeks or more rapidly with antibiotic treatment

3 – 4 weeks, antibiotic

erysipeloid can be resolve without treatment after __________ or more rapidly with ______ treatment

erysipeloid

Characterized by severe pain, swelling, raised and violaceous lesion with no pus

diffuse cutaneous form and bacteremia

Additional clinical forms of infection (both rare) are a __________ or without endocarditis

Penicillin G

treatment of Erysipelothrix rusopathiae

Nocardia

Thin, branching, and beaded aerobic bacteria

Nocardia

Filamentous

Nocardia

Weakly acid fast – cells have mycolic acid

Nocardia

Opportunistic pathogen

Causes nocardiosis

acquired by inhalation, a subacute to chronic pulmonary infection that may disseminate to the brain or skin

abscess formation

The usual pathologic process causes nocardiosis – acquired by inhalation, a subacute to chronic pulmonary infection that may disseminate to the brain or skin

Trimethoprim-sulfamethoxazole

treatment for nocardia (drug of choice)

amikacin, imipenem, minocycline, linezolid and cefotaxime

alternatives for treatment for nocardia

Surgical drainage or resection maybe required

treatment for nocardia

Actinomyces

Short club shaped or long thin beaded filaments

Actinomyces

Branched, unbranched

Actinomyces

Aerotolerant

actinomycosis

Actinomyces causes ________

Cervicofacial actinomycosis, Thoracic or pulmonary infection, Abdominal actinomycosis

actinomycosis has three common forms:

Penicillin (6 – 12 months)

Treatment for Actinomyces

Clindamycin and erythromycin

Treatment for Actinomyces

Cutibacterium acne

Formerly known as Propionibacterium acnes

Cutibacterium acne

Highly pleomorphic

Cutibacterium acne

Opportunistic pathogen causing acne vulgaris

Cutibacterium acne

Frequent cause of post-surgical wound infections

Propionibacterium acnes

Cutibacterium acne