Gram-Positive rods

Corynebacterium

• they are facultative anaerobes, gram-positive, non-spore forming rods that arranged in palisades and is club-shaped

• produces Babes-Ernst granules

• Catalase (+)

• Esculin Hydrolysis (-)

Corynebacterium urealyticum and C. pseudodiphtheriticum

• Corynebacterium species are glucose and maltose fermenters except:

Corynebacterium diphtheriae

• the most significant pathogen of the Corynebacterium genus, responsible for diphtheria.

• It produces a potent toxin that can cause severe respiratory illness and other systemic effects.

Exotoxin

• a major virulence factor of C. diphtheriae

Fragment A

• a fragment of C. diphtheriae that inhibits protein synthesis

• specifically, it is the diphtheria toxin, which leads to cell death and tissue damage in the host.

Fragment B

• a fragment of C. diphtheriae that binds to the cell surface and is essential for the toxin's activity, allowing entry of Fragment A into host cells.

Systemic Effect

• Toxin is absorbed in the bloodstream and carried systemically

• It affects the kidneys, heart, and nervous system

Cutaneous form

• Non-respiratory disease of C. diphtheriae

• More prevalent in the tropics

Loeffler’s serum agar

• an agar used to demonstrate pleomorphism and metachromatic granules of C. diphtheriae

• Lipid abundant

Cystine-tellurite blood agar (CTBA)

• a selective and differential agar used for C. diphtheriae

Corynebacterium amycolatum

• common on skin and most frequently recovered Corynebacterium species

• Opportunistic infections

  • Prosthetic joint infections, sepsis, and endocarditis

Corynebacterium jeikeium

• a Corynebacterium species in which the infection comes from the catheters or prosthetic devices (prosthetic valve endocarditis)

Corynebacterium pseudodiphtheriticum (Hoffman bacillus)

• a Corynebacterium species that has opportunistic infection, often endocarditis.

• can be found in nasopharynx

Corynebacterium pseudotuberculosis

• a Corynebacterium species that acquire through contact with sheep

Corynebacterium striatum

• a Corynebacterium species that is normal flora

• It is rarely infectious

Corynebacterium ulcerans

• a Corynebacterium species that causes mastitis in cattle

• It can be acquired by contact with animals or in unpasteurized milk

Corynebacterium urealyticum

• a Corynebacterium species that is pathogenic in urinary

Rothia dentocariosa

• a Rothia species that is normal oral flora

Listeria monocytogenes

• a gram-positive, nonsporulating forming rods (coccobacillus that often appear cocci)

• primarily infect animals

• Catalase (+)

• Esculin Hydrolysis (+)

• Grows at 4°C

• Motile at 25°C (umbrella type)

Listeriolysin O

• a virulence factor of Listeria monocytogenes that damages phagocytic membrane and prevents killing of the organism

• Hemolysin

Surface protein p60

• a virulence factor of Listeria monocytogenes that induces phagocytosis

Erysipelothrix rhusiopathiae

• a gram-positive, non-spore-forming, pleomorphic rods that can cause disease in animals (swine, turkey, sheep, fish)

• Catalase (-)

• H2S (+) on triple sugar iron (TSI)

• Gray or translucent colonies with a-hemolysis in blood or chocolate agar

Erysipeloid

• a disease caused by Erysipelothrix rhusiopathiae that produces painful swelling, usually on the hands or fingers.

Arcanobacterium

• a catalase negative bacteria that have narrow zone beta-hemolysis (black opaque dot on agar surface under the colony)

Arcanobacterium haemolyticum

• an Arcanobacterium species that causes pharyngitis and pruritic scarlatiniform rash with disquamation of the skin of the hands and feet.

Arcanobacterium pyogenes

• an Arcanobacterium species that causes sepsis and wound infections in those with animal contact

Arcanobacterium bernardiae

• an Arcanobacterium species that causes bacteremia, wound infections, urinary tract infections (UTIs), and septic arthritis.

Gardnerella vaginalis

• a short, pleomorphic gram-positive rod or coccobacillus (often stains gram-variable or gram-negative)

• grows in 5% to 7% CO2 at 35°C to 37°C in SBA or CHOC agar

Bacterial Vaginosis

• an infection caused by Gardnerella vaginalis creating a malodorous discharge

• Vaginal pH of greater than 4.5

Human Blood Bilayer Tween (HBT) Agar

• a medium of choice for Gardnerella vaginalis

Nocardia

• a gram-positive filamentous rods, weakly acid-fast and may stain gram-variable

• sometime resembling branched hyphae

• morphologically resemble fungi

Nocardia cyriacigeorgica and N. farcinica

• a Nocardia specie that causes confluent bronchopneumonia and necrosis with abscesses.

• No “sulfur granules”

Nocardia brasiliensis

• a Nocardia specie that causes cutaneous infection termed “actinomycotic mycetomas” (trauma to skin)

• “sulfur granules” present

Sulfonamide

• most common and effective anti-biotic for Nocardia

Sabouraud Dextrose Agar

• an agar that promote the growth of bacteria rich in fatty acid

Bacillus

• a gram-positive large rods with “empty” spaces

  • have endospores which makes them highly resistant to heat, drying, and chemicals.

Bacillus anthracis

• a large, square-ended gram-positive rods

• Bamboo appearance, “medusa head” or “beaten egg whites”

• a Bacillus species that causes anthrax

Pulmonary Anthrax (Woolsorter’s disease)

• a disease caused by Bacillus anthracis acquired through inhalation of spores

• sudden respiratory distress, disorientation, coma, and death

Gastrointestinal anthrax

• a disease caused by Bacillus anthracis acquired by ingestion of contaminated raw meat

Injectional anthrax

• a disease caused by Bacillus anthrax acquired by direct injection of the endospores into tissue.

• it causes necrotizing fasciitis, organ failure, shock, coma, and meningitis

Bacillus cereus

• a Bacillus species that causes food poisoning by distinct enterotoxins

Diarrheal syndrome

• a disease caused by Bacillus cereus that is associated with meat, poultry, and soups

• Incubation period of 8 to 16 hours

• Fever uncommon

• Resolves within 24 hours

Emetic form

• a disease caused by Bacillus cereus that is associated with fried rice

• Abdominal cramps and vomiting

• Incubation period of 1 to 5 hours

• Resolves within 9 hours

Clostridium perfringens

• a Clostridium species that produce double zone of hemolysis on Brucella blood agar

• boxcar-shaped

Clostridium tetani

• a Clostridium species that is heavily swarming in terminal spores

Clostridium septicum

• a Clostridium species that is heavily swarming in subterminal spores

Clostridium botulinum

• a Clostridium species that causes flaccid paralysis

Botulism

• has a toxin A through G, but only types A, B, and E are associated with human disease

• it prevents the release of acetylcholine

• can be acquired from home canning and home-cured meats

Tetanus

• a disease that inhibits neurons by inhibiting neurotransmitters