gram (+) cocci

staphylococcus

• Gram positive, facultative anaerobe, grape-like clusters of cells

• Catalase positive - important since it distinguishes from Streptococcus

hemolysis

breakdown of red blood cells

which bacteria is beta-hemolytic?

staphylococcus aereus

which bacteria is gamma-hemolytic?

staphylococcus epidermidis

exotoxin

toxin that bacteria secretes, travels, and causes damage

superantigen

antigen that strongly and excessively activates the immune system

how do s. aureus infections begin?

opportunistic infections: through breaks in skin, localized cutaneous infections, nosocomial infections

bacteremia

bacterial infection of the blood

septic shock

infection that causes organ failure and low blood pressure(death); caused by immune response to infection

scalded skin syndrome

result of an exotoxin produced by some s. aureus strains

• skin begins peeling off in sheets. May indicate bacteremia. Usually seen in newborns(infection of umbilical stump)

toxic shock syndrome

s. aureus disease: septic shock without the sepsis, caused by exotoxins into bloodstream; also caused by not changig bandages or tampons

s. aureus food poisoning

• bacteria gets into food that is left out, produces exotoxins in food

• when we eat it the bacteria are killed but the exotoxins poison our gut

• Hallmark effects: rapid onset + rapid recovery

treatment of s.aureus infections

antibiotics

MRSA

methicillin resistant staphylococcus aureus - a medical concern because methicillin has been a primary antibiotic for years

prevention of s. aureus infections

• keep infection from happening in the first place

• use proper aseptic and antiseptic techniques

streptococcus

• Gram positive, facultative anaerobe, chains of cells, catalase negative

• Some types are hemolytic

  • alpha-hemolytic (partly)

  • beta-hemolytic (very)

  • gamma-hemolytic (not at all)

lancefield groups

a way to label and classify streptococcus bacteria by letter; based on serotypes and some are ungroupable

lancefield group a

streptococcus pyrogenes

streptococcus pyrogenes

• beta hemolytic

• Strep Throat, Scarlet Fever, Impetigo

strep throat

non-invasive infection of the throat - pharyngitis

• Extremely sore throat

• Fever

• White spots on the throat

scarlet fever

non-invasive infection of the throat

• similiar symptoms to stret throat but causes a red rash on the body

impetigo

local skin infection

• pustules that crust over and ruptures on outer layer of skin/glands/follicules

necrotizing fasciitis

• “flesh eating bacteria”

• an infection that might be developed by streptococcus pyogenes — an invasive bacteremia and causes an opportunistic infections of wounds

• what finally kills people is that exotoxin A (superantigen) triggers a massive inflammatory response

  • causes toxic shock syndrome

rheumatic fever

• disease that develops long after having a Group A strep infection

  • It is an autoimmune disease

  • Portions of the bacterial cell wall (M protein) are highly antigenic (cause many antibodies to be made)

  • Causes an overactive immune system that attacks joints (reactive arthritis)

• 50% of patients develop heart problems due to the immune system attacking the M protein at the heart

• Antibiotic treatment is important so that the infection does not become large enough to trigger rheumatic fever

breeding ground of group b strep

vaginal flora

• can infect infants at birth and is significant cause of newborn meningitis

• prevented through antibiotics before/during birth that will prevent transmission

streptococcus pneumoniae

• causes pneumonia - infection of the lungs that causes the alveoli to fill with fluid

  It is called pneumococcus because it is a diplococcus

• THICK capsule, important in evading phagocytosis

• alpha-hemolytic

pneumonia

• difficulty breathing, fever, chest pain, positive chest x-ray

• Variety of causes: bacteria (most common and concerning), fungi, viruses

• not generally contagious(only problem for vulnerable immunocompromised people)

treatment of pneumonia

antibiotics and an expectorant(loosens mucus in lungs)

meningitis

when bacteria migrates from lungs to the blood (bacteremia) and blood to the brain

• Symptoms: fever, headache, sore/stiff neck

• Progresses to nausea, vomiting, convulsions, and coma

enterococcus

• Gram positive cocci, facultative anaerobe, bile resistant (able to grow in their presence)

• gamma-hemolytic

UTI

• Symptoms: painful urination, constant sensation of need to urinate, blood in urine, can lead to infection of kidneys if untreated, slight risk of contagion through sexual contact

• Treatment is important because it can infect the kidneys

• Unusual because the bacteria are intrinsically resistant to many antibiotics, can develop resistance rapidly, and are often associated with healthcare-acquired infections

• around 10% are nosocomial(usually from catheters)

lactococcus

Gram positive cocci, mostly in pairs

• ferments lactose into lactic acid → lowers pH → ruins environment for other bacteria → causes curdling

curdling

coagulation of milk proteins

lancefield group b

Streptococcus agalactiae