Microbiology Flashcards
Penicillin Resistance
- occurs from hydrolysis of beta lactate ring by bacterial beta lactamase in peri plasm of gram -
- alterations of beta lactam targets (Penicillin binding proteins Change configuration)
Penicillinase resistant penicillins
Methicillin = not used clinically because of toxicity. Don’t give to MSSA patient due to interstitial nephritis. Used to determine resistant strains of Staph
Nafcillin
Oxacillin
Dicloxacillin
Aminopenicllins
Ampicillin and Amoxicillin
- penicllinases will inactivate this
- get rash all over body when given for mononucleosis (EBV)
Work on
Gram + bacteria and Gram - rods (HELPS)
Bacterial Cell walls
Gram Positive
- have lipotechoic acids that contain lipids and techoic acid
- induces IL1 and TNFalpha
Gram Negative
- have an outer membrane that is the site of endotoxins (LPS)= induces IL1 and TNFalpha –> can cause septic shock
- has both inner and outer membrane
- Periplasmic space = site of beta lactamase (helps break beta lactam rings of penicillins and cephalosporins) ==> inbetween the 2 membranes
Both have sex pilli, flagella, and fimbriae
Glycocalyx = hard (Capsule) and slimy
Quellung reaction
Helps to tell you if the bacteria has a capsule
- Anti-capsular serum added to bacteria
- capsule appears swollen under microscope
Encapsulated orgnisms (Even some pretty nasty killers have shiny bodies) –> bad for asplenic patients
- E. coli (some strains)
- S. Pneumo
- Pseudomonas A
- Neisseria meningitidis
- Klebsiella pneumoniae
- Heamophilus influenza type B
- Salmonella typhoon
- Group B strep
- Cryptococcus neoformans
Bacteria that have weird cell walls = not visualized well with Gram Stain
Mycoplasma
- sterols
- no cell wall
Mycobacterium
- mycolic acid
- very resistant
Treponema
- spirochetes
- seen better with dark field microscopy
Legionella
Spore formers
Clostridia
Coxiella Burnetti
Bacillus species
MPO (myeloperoxidase deficiency)
- defective production of HOCL from H2O2
- Nitroblue test will be normal and change color to blue
- patient will be asymptomatic
- increased risk for Candida
Viral Basics
All RNA viruses replicate in the cytoplasm except for influenza virus and retroviruses
All DNA viruses replicate in the nucleus except the pox virus family
Viral Genetics
- reassortment = occurs in viruses with segmented genome. When two viruses are affecting the same cell they can create new types of viruses by exchanging segments (occurs more in RNA viruses)
- recombination = occurs when 2 viruses infecting same cell, genes are exchanged during replication. ==> go to page 156
- complementation = Hep D and Hep B
Virus Ploidy
- copies of RNA or DNA
- all RNA/DNA viruses are haploid = contain 1 copy of either RNA OR DNA
- retroviruses = contain 2 copies of ssRNA
DNA viral genomes
- most DNA viruses - dsDNA except Parvovirus
- most DNA viruses - linear DNA except page 157
Envelopes
- most viruses get their envelope from the host cell plasma membrane
- the herpesvirus gets its envelope from the nuclear membrane
Thayer Martin
- used to isolate Neisseria species
- contains vancomycin to inhibit the growth of gram +, colistin to inhibit gram negative, nystatin to inhibit the growth of fungi, and trimethoprim to inhibit the growth of gram negative organisms other than Neisseria
Acute Rheumatic Fever
- follows an untreated episode of GAS pharyngitis and not GAS skin infection
- GAS skin infection would show PSGN > or ARF
What is the virus that gets its envelope from the nucleus?
Herpesvirus is the only Virus that gets it envelope from the nuclear membrane.
All other viruses acquire their envelope from the plasma membrane as they exit the cell.
