MICRO Flashcards
What are the GP rods/bacilli?
Clostridium Bacillus Corynebacterium Listeria Mycobacterium Gardnerella
What are the branching filamentous bacteria?
How do they gram stain?
Actinomyces & Nocardia
Gram positive
Which bacteria does not have a cell wall?
How does it gram stain?
Mycoplasma. Does not gram stain!
What is PG of bacteria made of? What enzyme significant to structure
Sugar backbone w/ peptide side chains, crosslinked by transpeptidase
Differentiate GP vs GN bug wall structure
GP: Lipoteichoic acid, thicker PG layer
GN: LPS/Endotoxin, periplasm, thin PG layer
What induces TNF & IL-1 in GN & GPs?
GP: Lipoteichoic acid
GN: Lipid A
What are capsule made of? What is the exception
Polysacharide
(EXCEPTION: Bacillus anthracis contains D-glutamate, a Polypeptide)
What structure allows bugs to adhere to foreign substances?
Glycocalyx
normal flora for skin?
Staph epidermidis
S. aureus, yeasts, & other strep species
normal flora for mouth (oropharynx)?
Viridins strep (Strep mutans), Candida, H. influenza (type w/o capsule), Neisseria
normal flora of adult colon?
Bacteroides fragilis > E. coli
Fusobacterium, Lactobacillus,Enterococcus faecalis, GN anaerobic rods
normal flora in baby colon? (being breast-fed)
Bifidobacterium
normal flora in vagina?
Lactobacillus. E. coli, group B strep, Corynebacterium, Candida
MC cause of neonatal meningitis? MC transmission source?
Group B strep! During natural delivery, from vagina normal flora
List the 3 main causes of newborn (0-6mon) meningitis
1) Group B strep
2) E. coli
3) Listeria
what is polycistronic mRNA and give example? Where is it found?
single mRNA can code for several genes. Found in Prokaryotes, NOT Eukaryotes.
Ex; Lac operon in E. coli
How does bacteria replicate?
Binary fission asexual
What component of Fungal cell membrane target of drugs (different from bacteria)?
Ergosterol
normal flora of body organs?
NONE! Sterile, like blood should be
name the one bug that can replicate in stomach?
H pylori
virulence factor for E. coli to cause UTI? What type of bugs this found?
Pili! How it clings to urethra against urine stream
Pili found in GN bugs
Explain chronic infection by Neisseria?
Pili change to avert immune response = antigenic variation
Adherence structure for GP bugs?
Teichoic acids
Adhesions are important virulence factor for which toxins?
pertussis & hemagglutinins
Which bugs use IgA protease?
Strep pneumo
H. influenza type B
Neisseria
Obligate aerobe w/ a capsule?
Pseuodomonas aeruginosa
Fungi w/ a capsule?
Cryptococcus neoformans
MC virulence factor of bacterial meningitus?
Capsules! help to cross BBB (very slippery) & evade immune response
Anti-phagocytis virulence factors w/ associated bugs
Protein A- S. aureus
M protein- GAS
Pili- N. gonorrhea
What bugs do phase variation?
Trypanosoma brucei rhodesiense &
Trypanosoma brucei gambiense
Phase variation in flagella?
Enterobacteriaceae
what tests used to detect capsule?
Quelling reaction and Latex particle agglutination
Which bugs are intracellular- facultative?
Salmonella Neisseria Brucella Listeria Francisella Legionella Yersina Mycobacterium
Obligate intracellular bugs?
Chlamydia & Rickettsia
Describe intracellular mechanisms of TB & Listeria?
TB: (-) phagolysosome fusion
Listeria- leaves phagosome before phagolysosome fusion
How does a bug invade a non-phagocytic cell?
Invasins
Patient has Chronic Granulomatous Disease. Increased risk of infection by…?
Catalase + bugs!
SPACE MaN SaM
S. aureus, Pseudomonas, Aspergillus, Candida, E. coli, Mycobcaterium, Nocardia, Serratia marcescens
Obligate aerobes ? Fermentation method?
Nocardia
TB
Pseudomonas aeruginosa
Bacillus
No fermentation
When do you see infection by Pseudomonas aeruginosa?
Diabetes
Burn wounds
Nosocomial pneumonia
CF patients w/ pneumonia
Urease + bugs
CHuck norris hates PUNKSS
Cryptococcus H. pylori Proteus Ureaplasma Nocardia Klebsiella S. epidermidis S. saprophticus
Describe how vaccines made for capsular bugs?
Capsules (polysaccharide) are conjugated to a protein (i.e. Prevnar). This promotes Tcell activation and later class switching. If not conjugated, only IgM abs made
Type III secretion system? Bugs?
Tunnel from bug to macrophage to inject toxins
E. coli, Salmonella, Yersinia, Chlamydia, Pseudomonas
Rheumatic fever example of what HS?
Type 2
Cross reaction of bacterial-induced Abs w/ tissue Ags (endoderm)
Granulomas seen in what type of bugs? What type of HS?
Intracellular facultative Type 4 (DTH)
Virulence factors of TB?
Nothing release. The immune response is what is damaging
Which organism can block the bile duct?
Ascaris worm
Heat stability of toxins?
Exo are destroyed @ 60C, except enterotoxin by Staph
Endo stable @ 100C for an hour
Endo vs Exotoxin: secretion
Exo are secreted, Endo not secreted
Toxin vaccination for Endo and Exo
Vaccines for Exotoxins using toxoids
NONE for Endo
Which bugs are Beta-hemolytics?
S. aureus, Strep pyogenes, Streptotoccus agalactiae, Listeria monocytogenes
Coagulase pos, GP cocci virulence factors? How
Protein A- (-) phago & complement fixation TSST Enterotoxin Catalase, Coagulase Exfoliative toxin Alpha-toxin (makes cell pores)
GP cocci in clusters, catalase (+).
Causes what diseases?
Food poisoning- heat stable enterotoxin Toxic Shock syndrome- a super Ag Scalded skin syndrome- exfoliative toxin MRSA (Beta-lactam resist) Acute nacteria; endocarditis Osteomyelitis Pneumonia (nosocomial, post-viral) Surgical infection (MCC) Bone pain + fever in kid (unless Sickle) Impetigo
S. aureus as normal flora and how transmitted?
Nares & skin
touching, sneezing, nose-picking, surgical wounds, food (custards, potato salad, canned meat)
Predisposing factors for S. aureus infection
Surgery/wounds. Tampons, CGD, CF
How does Toxic shock syndrome present? Mechanism
Mechanism: TSST (a super-Ag) binds to MHCII & TCR–> polyclonal Tcell activation
Sx: Fever, shock, desquamation, rash, vomit, end-organ failure
Explain skin infections by S.aureus
Exfoliative toxin- cause Scalded skin syndrome & Bullou Impetigo
Which GPC, catalase pos bug infects IV catheters and how?
Staph epidermidis via biofilms
Strep pneumo MCC of what?
Gram stain look?
Meningitis (6months and older, even old)
Otitis media (kids)
Pneumonia- rusty colored sputum
Sinusitis
Gram stain: lancet shaped, GP diplo (“halo” sometimes, due to capsule)
Draw GP flowchart. Include cocci, Rods, and branching bugs
pg 127
What predisposes to Strep pneumo infection?
influenza or measles infection COPD CHF Asplenia and/or HgbS--> septicemia Alcoholics (dont confuse w/ Klebsiella, which in this group)
Which bugs are alpha hemolytic? How to differentiate among them?
Viridans strep & Strep pneumo
Optichin disk: O VR PS
Transmission of GPC, catalase neg, Optochin resistant
normal flora in Oropharynx
Viridinas strep diseases and causes
Dental caries & plaque- Strep mutans (Dextrans..)
Subacute bacterial endocarditis @ damaged valve plus dental work w/o antibiotics- S. sanguis
Fibrin/PLT bind to damaged site, and Viridans binds to fibrin via Dextrans polysach
Subacutre endocarditis in colon cancer patient, whats da bug?
Streptococcus bovis
Disease of GAS
Pyogenic: phayngitis, cellulitis, impetigo (honey-crusted lesions)
Toxigenic- scarlet fever, necrotizing fasciitis, TS-like syndrome
Immunologic- rheumatic fever, acute glomerulonephritis
How to detect GAS, other than gram stain?
ASO titer
Bacitracin sensitive
PYR positive
JONES criteria, use and define
Diagnose Rheumatic fever (Type 2 HS) Joints- polyarthritis O- carditis Nodules- subcutaneous Erythema marginatum Syndenham chorea (involuntary limb movement)
What diseases caused following a Strep pyogenes infection (sequelae infections)
Phayngitis can cause rheumatic fever and acute glomerulonephritis
RF (HS 2): 2 wks after, Abs attack heart (molecular mimicry)
AGN (HS 3): Due to M-protein. Also after skin infection
Sx of Scarlet fever? Associated bug?
Sx: scarlet rash (sparing face). strawberry/scarlet tongue, scarlet throat. Sandpaper rash (spares hands & soles), desquamation of hands soles
GAS
How does Strep pyogenes spread?
Streptokinase, Streptococal DNAse, Hyaluronidase
Diseases of GBS?
Prophylaxis?
Tx?
Sepsis, pneomonia, &
MCC of Neonatal meningitis:
Screen women 35-37wks pregnancy. If +, give intrapartum penicillin or ampicillin
(Clindamycin or erythromycin in allergies)
Tx: Ampicillin w/ aminoglycoside or cephalosporin
Lab testing of GBS
CAMP factor, enlarging hemolysis area by S. aureus
Bacitracin resistant
Beta hemolytic
Hippurate positive
Lab presentation of Enterococci
Lancefield group D
Variable hemolytic patterns
Growth on 6.5% NaCl & bile
Diseases of Group D Strep
Examples of bugs
Penicillin G resistant cause UTI,
biliary tract infection,
subacute endocarditis- from procedures, (cystoscopy), from colon, perenium, genitals
Enterococcus faecalis & E. faecium