Cocci Pathogens (3)

Why is gram stain so important in clinical microbiology?

The importance of gram stain is differentiating the classification of the bacteria based on their cell walls.

Genus Staphlycoccus +

Gram +

Catalase +, salt tolerant

Affects the skin /nasal

Three types: Saprophyticus, Epidermis, Aureus

Staphylococcus Aureus +

Characteristics: anaerobic, no spores, environmentally resistant

Virulence Factors: Coagulase+, Hemolysin+, Toxic Shock Syndrome, can develop drug resistance towards penicillinases

Demographic: Elderly, immunocompromised, hospital patients

Transmission: direct contact, fortes

Antibiotics: Bacitracin, penicillin

Staphylococcus Aureus +

Characteristics: anaerobic, no spores, environmentally resistant

Virulence Factors: Coagulase+, Hemolysin+, Toxic Shock Syndrome, can develop drug resistance towards penicillinases

Demographic: Elderly, immunocompromised, hospital patients

Transmission: direct contact, fortes

Antibiotics: Bacitracin, penicillin

Staphlycoccus Aureus Diseases

Local cutaneous- abscess, folliculitis

Systemic- osteomyelitis, meningitis that eventually turns septic (disease will spread to multiple organs)

Toxigenic- Toxic Sock syndrome caused overactive immune system, the Enterotoxins causing food poisoning while the Exfolative Toxin causes Staphyloccal Scalded Syndrome (SSSS)

Staphylococcus sapropyticus +

-skin, nose, intestines, and vagina

-UTI’s

-high prevalence in sexually active young women

• Differential characteristic: coagulase - and resistant to novobiocin

Staphylococcus epidermis +

-skin

-“Accidental Pathogen” caused by contamination, when the capsule allows biofilm formation on medical devices

• Differential characteristic: coagulate- and susceptible to novobiocin antibiotic

Genus Streptococcus +

-oral and nasal microbiome

Catalase -

Differential characteristic: type of hemolysis (Alpha or Beta)

What are the two Alpha hemolytic and viridian group Streptococcus?

Strep. pneumoniae- upper respiratory tract, 2 vaccines pnemovax and prevnar 13, can cause otitis and meningitis, susceptible to optochin antibiotic

Strep. mutans- mouth, causes cavities, major bacteria in dental plaque, resistant to optochin antibiotic

Fructose turns into lactic acid causing a drop in pH in that area of the tooth causing a pit to form. This causes the erosion of the enamel and this introduces other bacteria to enter and infect the gums causing gum disease

Streptococcus pyogenes +

-anaerobic , environmentally sensitive

-Virulence factors: fimbriae- aid in attachments that invade the immune system

C-carbohydrate- protect against lysosome

C5a protease- inhibit complement

Capsule and M- protein are against phagocytosis

Hemolysis+, Streptokinase+ (dissolves blood clots), Erythrogenic toxin

What is a prophage? Which gram positive cocci acquires a toxin gene from a prophage?

A prophage is the genetic material of a bacteriophage that carries a toxin. A gram positive cocci that acquires an erythogenic toxin from a prophage is streptococcus pyogenes.

How are Staphlycoccus and streptococcus differentiated?

Staphylococcus- salt tolerant, catalase +, affects the skin

Streptococcus- catalase -, affects the oral and respiratory microbiome

Why are neisseria gonorrhoeae infections so common?

Because neisseria gonorrhoeae have no capsule the pilli attaches to the host cell and IgA proteas cleaves IgA antibodies and is secreted onto the mucous membrane. Because this bacterium is able to break down the antibodies and remain viable within the phagocytes this infection is commonly acquired multiple times.

Why is diagnosing Neisseria meningtidis so important?

Neisseria meningtidis should be diagnosed immediatley because this infection inflames the meninges and causes neurological symptoms like stiff neck, headaches, and seizures that can be fatal.

what virulence factor was common to all the cocci pathogens?