Quesmed Microbiology Qs Flashcards
What is Group B Strep?
Streptococcus agalactaei
Gram positive cocci which is the most common cause of neonatal meningitis and sepsis.
What is streptococcus pneumoniae?
Alpha haemolytic + diplococcus
Causes: pneumonia, meningitis, ear/eye/sinus infection
It is facultative aerobe, which can grow with or without o2 and appears in a PAIR
What are the group A strep?
Streptococcus pyogenes
They are typically found in the nose and throat and are beta haemolytic,.
How do alpha haemolytic organisms appear on agar?
Partial RBC breakdown so there is a ring of partial clearness around them on agar. Streptococcus pneumonia is a beta haemolytic;
How do beta haemolytic organisms appear on agar?
Completely break down RBCSs and have a clear ring surrounding them. Group A strep is a beta haemolytic organism.
Which infections are caused by Group A Strep?
Streptococcus pyogenes causes:
Tonsillitis
Otitis Media
Cellulitis
Toxic Shcok syndrome
Impetigo
Which bacteria causes delayed infection?
Streptococcus pyogenes. Post streptococcal complications include:
Post-streptococcal glomerulonephritis
Rheumatic fever
Scarlet Fever
Why do complications occur with streptococcus?
Post-streptococcal complications are a result of antigenic cross-reactivity to streptococcal M protein, which resembles proteins present in the bodies connective tissue.
What is rheumatic fever?
Occurs after throat infection with Strep A, that causes red and swollen tender joints.
What is the herd immunity level required for diphtheria?
75%
What are the features of helicobacter pylori?
Spiral-shaped gram-negative bacilli which requires faeco-oral transmission. It is associated with peptic ulcer disease, gastric cancer and lymphoma of the MALT.
NO ASSOCIATION TO GERD.
How does vibrio cholerae work?
Reverses concentration gradient of ions on the channel. promoting adenylate cyclase activity and causing increased intracellular [cAMP]
What is osmolality?
Concnetration of solutes, measured in KILOGRAMS.
How does oral rehydration therapy work?
Increases action of Na+/glucose transporter to cause the drawing in of water passively into the lumen, due to a increase in osmolality.
Gram positive
Thick peptidoglycan cell wall and produce only exotoxins. Turns blue/violet on gram stain.
Gram negative bacteria
Outer LPO cell wall, inner thin peptidoglycan. Produces exotoxins and endotoxins. Turns pink on gram stain.
WHat is the most common cause of meningitis in babies and elderly?
Neisseria meningitis is the most common cause of meningitis in babies, children and elderly. It is a gram negative cocci which produces ENDOtoxins.
What is the most common cause of meningitis in newborns?
Group B strep, a beta-haemolytic organism carried in the vaginal canal of 1/4 of women,.
What is the most commmon cause of meningitis in neonates?
Neisseria
What is the most common cause of meningitis in young adults?
Gram positive species, such as Streptococcus.
What is the difference between Streptococci and Staphylcocci?
Streptococci tend to be in chains, Staphylococci tend to be in clusters.
Catalase positive in Staphylococci vs catalase-negative in Streptococci
What is the most common cause of tonsillitis?
Streptococcus pyogenes, which will typically lead to rheumatic fever with swollen and red joints.
What infections does Staph Aureus cause?
Osteomyelitis
Septic arthritis
Toxic Shock syndrome through exotoxins
Pneumonia
Which antibiotic treats MRSA?
Vancomycin
