BACTERIOLOGY

Clostridium

Firmicutes

• Rod-shaped

• obligate anaerobic cells

• contain endospore that usually distend the cell

Clostridium tetani

• worldwide distribution in soil and feces of horses or other animals

• Tennis racket appearance

Clostridium Tetani

causes

• sustained muscle contractions (prevents release of GABA and glycine, increases ACh)

• Lock jaw/Trismus

• Risus sardonicus

• Opisthotonos

Clostridium perfringens

Common cause:

• food poisoning

• gangrene

Possesses an alphatoxin (lecithinase)

Clostridium perfringens

• Possesses an alphatoxin

Beta toxin

Clostridium perfringens

what toxin

• Food poisoning ( pig bel) enteritis necroticans

Alpha toxin

Clostridium perfringens

what toxin

• Gas gangrene

Clostridium difficile

Most common cause

• superinfection

Clindamycin and broad spectrum antibiotics

Clostridium difficile

Pseudomembranous colitis

• severe diarrhea

• abdominal cramping

• fever

Clostridium botulinum

Produces the most potent neurotoxin (blocks the release of acetylcholine from presynaptic nerve terminals)

• flaccid paralysis

Clostridium botulinum

• fatal food poisoning

• Botulinum toxin

  • Floppy baby: Hypotonia

Mouse Neutralization Test

Clostridium botulinum

• toxin is identified by??

Bacillus

Firmicutes

• Rod-shaped

• endospore-forming cells

• Obligate aerobic soil bacteria

• Some species produce antibiotics, and some are used as insecticides

Bacillus anthracis

Only bacteria with amino acid capsule

(D- glutamic acid in capsule) §

Medusa head colony:

• Square ends/Bamboo pole

Virulence:

• Protective antigen, Edema factor, Lethal factor)

Bacillus anthracis

Causes anthrax

• Cutaneous: exotoxin causes localized tissue necrosis

• Gastrointestinal: rare but fatal

woolsorter’s disease

Bacillus anthracis

• Respiratory:

Mc Fadyean Reaction

Bacillus anthracis IDENTIFIED BY:

• Polychrome methylene blue for stainin capsule

  • capsule is pink,

  • bacilli stained dark blue

Bacillus cereus

• Facultatively anaerobic,

• toxin-producing grampositive bacterium found in soil, vegetation, and food

• Found in starchy food

Heat labile toxin

Type of toxin of CEREUS

• E. coli

  • Diarrheal type

• From: Vegetable, Meat, & Paultry

Heat stable toxin

Type of toxin of CEREUS

• S. aureus

  • Vomiting type

• From: Stary ex. Fried Rice

CATALASE TEST

TEST

• Differenciate STAPH from STREP

HYDROGEN peroxide

CATALASE TEST

• USE

With Bubbles

• STAPH

Without Bubbles

• STREP

CATALASE TEST

• With Bubbles

• Without Bubbles

COAGULASE TEST

TEST

• Identify STAPH Aureus from different STAPH

Staphylococcus

Firmicutes

• Occurs in grape-like clusters

• Pathogenic species: aureus

• Most important species in this group

• Facultative aerobes

• Can survive at high osmotic pressure and low moisture (nostrils and on skin)

Staphylococcus aureus

CAUSE

• ACUTE BACTERIAL ENDOcarDITIS

NOVO bio CIN

ANTIBIOTIC

• use to identify type of STAPH

Exfoliatin Toxins

Staphylococcus aureus

Exotoxins

• CAUSE: SSS

  • Scalded skin syndrome 

Staphylococcus aureus

Diseases by exotoxin release

• Gastroenteritis

• Toxic shock syndrome

  • With systemic manifestations

• Scalded skin syndrome (Ritter Disease) 

  • Without Systemic manifestations

Direct Organ Invasion

• Skin infections

• Acute bacterial endocarditis

• Urinary tract infection

Staphylococcus saprophyticus

Novobiocin resistant

• Non-hemolytic

• Coagulase negative

Staphylococcus saprophyticus

Causes

• honeymoon cystitis

Staphylococcus epidermidis

DNA gyrase inhibitor

• Has the ability to adhere to artificial materials in the body (e.g. catheters and prosthetic heart valves)

Frequently isolated in infected indwelling catheters:

• Prosthetic Heart Valve Endocarditis

• AUREUS

• EPIDERMIDIS

Novobiocin sensitive STAPH

Lactobacillus

Firmicutes

• Some are normal flora of the human body

• Also used commercially in the production of fermented foods like sauerkraut, pickles, buttermilk, and yogurt.

• Acid tolerant, produces lactic acid as final byproduct

Streptococcus

Firmicutes

• Spherical, gram-positive bacteria

• Typically appear in chains or in pair

• Responsible for more illnesses and causing a greater variety of diseases than any other group of bacteria

• Classification: Hemolysis test and Lancefield

• Beta-hemolytic streptococci Produce streptolysin, a hemolysin that forms a clear zones of hemolysis on blood agar

Alpha Hemolytic

Hemolysis Test

• Incomplete/ Partial Hemolysis

• Greenish Grayish

• EX:

  • S. Pneumoniae

  • S. Viridans

Beta Hemolytic

Hemolysis Test

• Complete Hemolysis

• Colorless

• EX

  • S. Agalactiae

  • S. Pyogenes

Gamma Hemolytic

Hemolysis Test

• No Hemolysis

• No Change In Color

• EX

  • Enterecoccus Faecalis

  • S. Mutans

Hemolysis Test

is used in the empirical identification of microorganisms based on the ability of bacterial colonies grown on agar plates to break down red blood cells in the culture

Lancefield

A system of classification that classifies catalasenegative Gram-positive cocci based on the carbohydrate composition of bacterial antigens found on their cell walls

• Group A - Streptococcus pyogenes

• Group B - Streptococcus agalactiae

• Group C - Streptococcus equisimilis, Streptococcus equi, Streptococcus zooepidemicus, Streptococcus dysgalactiae

• Group D - Enterococci, Streptococcus bovis

Streptococcus pyogenes

• Beta hemolytic

• Sensitive to Bacitracin

Streptococcus pyogenes

Possesses M protein

• M-PROTEIN: Major virulence factor that has the ability to inhibit phagocytosis in non-immune humans 

Streptococcus pyogenes

Rashes in Scarlet fever

• Produces Streptolysin S and O

Bacitracin

USE To differentiate from B. subtilis

Pharyngitis

Diseases caused by S. pyogenes

• is the most common disease caused by Streptococcus pyogenes.

Erysipelas

Diseases caused by S. pyogenes

• is a massive brawny edema and a rapidly advancing margin of infection.

• Brawny edema: swelling that is usually dense and feels firm due to the presence of increased connective tissue

Puerperal fever

Diseases caused by S. pyogenes

• is a septicemia originating in the infected wound following childbirth.

Scarlet fever

Diseases caused by S. pyogenes

• is caused by strains producing one of two closely related erythrogenic toxins. It can accompany pharyngitis or a streptococcal skin infection. Sore throat and rashes

Rheumatic fever

Diseases caused by S. pyogenes

• is the most serious sequela of hemolytic streptococcal infection because it results in damage to heart muscle and valves.

Streptococcus agalactiae

Known as group B beta-hemolytic streptococcus 

Streptococcus agalactiae

Causes

• neonatal sepsis and pneumonia

  • With Capsule 

  • Part of normal flora of vagina, mouth, urethral mucous membrane, GIT

Streptococcus pneumoniae

Encapsulated cocci, non motile, lancelet-shaped, fastidious, Part of oropharyngeal flora

ALPHA HEMOLYTIC

• Lancet-shaped diplococcus

  • major cause of adult pneumonia

  • most common cause of otitis media

  • most common cause of adult meningitis

Optochin Test:

Streptococcus pneumoniae

Determined by:

• Differentiate Pnemoniae From Viridans

  • a derivative of Quinine; VROPS (Viridans Resistant [to] Optochin, Pneumoniae Sensitive

Optochin

Antibiotic USED to Differentiate Pnemoniae From Viridans

• Resistant = Viridans

• SENSITIVE = Pneumoniae

Optochin

• Resistant

• SENSITIVE

Quellung reaction

Streptococcus pneumoniae

Determined by:

If it is S PNEMONIAE

• Negative = Viridans

• Pneumococci + anti-serum and methylene blue = swollen capsule (Viridans = negative)

Streptococcus viridans

Cause

• Subacute Bacterial Endocarditis

• • No group classification

  • Part of the normal oral flora

  • a-hemolytic

  • Not inhibited by optochin

  • Differentiate from pneumococci

  • If introduced into the bloodstream it may (SBE) ( Gradual onset as compared to Acute Endocarditis)

Streptococcus mutans

• Gamma-hemolytic

• Primary cause of dental caries

• Lives primarily in biofilms on the tooth surfaces

Enterococcus

Firmicutes

• Relatively hardy microorganisms adapted to areas of the body that are rich in nutrients but low in oxygen

• High resistance to most antibiotics E. faecalis and E. faecium

• Responsible for most infection of surgical wounds and the urinary tract

• Can enter the bloodstream through indwelling catheters