Final Exam Flashcards
(129 cards)
1
Q
Pleomorphic
A
bacteria variable in shape
2
Q
Cell envelope
A
cell wall, plasma membrane, outer membrane (gram neg only), Periplasm (gram neg only)
3
Q
Cell wall
A
rigid part = peptidoglycan composed of N-acetylglucosamine and N-actylmuramic acid + tetra peptide
confers protection
takes part in cell division
responsible for shape of bacterial cell
posses target sites for antibiotics, lysozyme and bacteriophages
4
Q
gram positive cell wall
A
many layers of peptidoglycan
5
Q
lipoteichoic acid and wall techoic acid
A
major surface antigens of gram positive bacteria
6
Q
gram negative cell wall
A
v few layers of peptidoglycan and an outer membrane
7
Q
gram neg outer membrane
A
bilayered structure with lipopolysaccharide
porins allow passive diffusion of low MW hydrophilic molecules
large antibiotics penetrate the outer membrane slowly = high resistance in gram neg bacteria
8
Q
lipopolysaccharide
A
- consists of lipid A = endotoxin of gram neg bacteria toxicity associated with the lipid portion and the O-polysaccharide is the major surface antigen
9
Q
spheroblasts
A
cell wall removed in gram neg bacteria
10
Q
protoblasts
A
cell wall removed in gram pos bacteria
11
Q
L-forms
A
removal of cell wall results in wall-less non-viable bacteria BUT if they are able to grow and divide - L-forms
unstable: revert back to cell wall containing state when inducing stim is removed (penicillin)
stable: do not revert back to normal state
12
Q
mycoplasma
A
naturally occurring bacteria which lack cell wall
13
Q
cytoplasmic membrane functions
A
permeability and transport
biosynthetic functions
electron transport and ox phosphorylation
chemotactic systems
- deepest layer of the cell envelope
thin semi-permeable layer consisting of proteins and phospholipids
14
Q
plasmids
A
extrachromosomal double stranded circular DNA molecules capable of replicating independently of the bacterial chromosomes - toxigenicity and drug resistance
15
Q
glycocalyx functions
A
capsule or slime layer
role in adherence of bacteria to human tissues - infection
enhances virulence
role in biofilm formation
16
Q
peritrichous flagella
A
numerous flagella all over the bacteria
17
Q
monotrichous flagella
A
single polar flagellum
18
Q
lophotrichous flagella
A
tuft of flagella at one end
19
Q
amphitrichous flagella
A
flagella at both poles of the cell
20
Q
pili
A
thin short filamentous appendages found mainly in gram neg bacteria - twitching and gliding motions, conjugation sex pili, adherence
21
Q
fimbriae
A
thin short filamentous appendages found mainly in gram neg bacteria made of structural protein pilin
adherence
biofilm formation
22
Q
endospores resistance
A
coat, low water content, low metabolic activity, high conc of Ca dipicolinic acid makes resistance to heat and drying
23
Q
obligate aerobes
A
pseudomonas aeruginosa (gram neg), bacillus (gram pos)
24
Q
obligate anaerobes
A
clostridium
25
facultative anaerobes
live with or without oxygen
staphylococci (gram pos) E. coli (gram neg)
26
aerotolerant anaerobes
don't use aerobic metabolism but have some enzymes that detoxify ox poisonous forms - radicals
27
microaerophiles
require oxygen levels from 2-10% limited ability to detox H202and superoxide radicals - H pylori
28
hyaluronidase
splits hyaluronic acid - important component of connective tissue - aids in spreading infection for microbe
29
coagulase
works with blood factors to coagulate plasma and leads to formation of fibrin wall around the organism protects from phagocytosis
30
hemolysin and leukocidins
dissolve RBC and destroy leukocytes/macrophages
31
IgA1 protease
degrades IgA - allows organism to adhere to mucous membranes
32
quorum sensing
Bacteria communicate with each other
Cell-cell communications via signalling molecules that allow bacteria to share info on cell density and adjust gene expression accordingly
Reduce gene expression if favours survival
33
indirect ELISA
receptor antibodies bind to the bound autoantibodies from the sample forming complex with immobilized antigen, autoantibody, and labelled reporter antibody
34
direct ELISA
secondary antibody binds to the bound protein from the sample forming complex consisting of immobilized antibody, protein and labelled secondary antibody
35
specimen collection
1. quantity of material must be adequate
2. sample must be representative of the infectious process (sputum not saliva)
3. contamination of the specimen must be avoided by only using sterile equipment and aseptic technique
4. specimen must be taken directly to the lab and examined promptly - special transport media prevent drying and stabilize conditions
5. before antimicrobials are admin
36
complex media
exact chem composition isn't known
contains yeast extract
nutrient broth, trypticase soy agar, MacConkey agar
enriched: added blood for fastidious organisms
37
selective media
contains substances that favour or inhib the growth of specific organisms
eosin methylene blue and crystal violet dyes and bile salts - inhib growth of gram pos bacteria without adversely affecting most gram neg (not the fastidious ones)
38
differential media
presence of visible changes in the growth media or dif in the appearance of colonies help differentiate various kinds of bacteria growing on the medium
blood agar - enriched and differential - hemolytic properties and fastidious
MacConkey agar - selective and differential
39
MacConkey agar
selective + differential
crystal violet inhib growth of gram pos so allows for isolation of enteric gram neg incorporation of lactose and pH indicator neutral red permits differentiation of enteric bacilli on the basis of their ability to ferment lactose - produce enough acid by fermenting lactose to reduce the pH below 6.8 the neutral red colorless turns red
latose fermenting is red but nonlactose fermenting is colorless
40
Protein A
Staph aureus
inhibits IgG complement cascade allows bacteria to bind to immune cells and prevent clearance from site of infection
41
pathogenicity
structures/enzymes that evade phagocytosis
production of enzymes
production of toxins
42
staph aureus pathogenicity
protein A, coagulase, bacterial capsule
43
staphylococcus enzymes
coagulase, hyaluronidase, staphylokinase, beta-lactamase
44
staphylokinase
opposite of coagulase - activates plasminogen to form plasmin which digests fibrin clots
45
Staphylococcus exotoxins
hemolysins, exfoliative toxins, toxic shock syndrome toxin, enterotoxins
46
Group A strep
S. pyogenes virulence factors
Capsule, Protein M (antiphagocytic), pyrogenic exotoxins (erythrotoxigenictoxin)
streptokinase (fibrinolysin)
hemolyisn - beta hemolytic
hyaluronidase
47
anthrax toxin
protective antigen - mediates entry
edema factor
lethal factor - death
48
ideal antimicrobial
effective, broad spectrum, non toxic, doesnt result in drug resistance - no agent has all of these qualities
49
tetracycline
broad spectrum antibiotic (protein synthesis inhibitor) with activity against gram pos and gram neg mycoplasma chlymdia
forms complexes with Ca incorporated into bones and dev teeth--> malformation of skull and stained weakened tooth enamel
50
vancomycin
narrow spectrum antibiotic (inhibits cell wall synthesis) with activity against gram +
51
antibiotic side effects
toxicity - liver kidney nerves
disruption of normal microbiota - secondary infections
52
antimicrobial mechanisms of action
inhibitors of cell wall synthesis
inhibitors of cell membrane function
inhibitors of protein synthesis
inhibitors of DNA and RNA synthesis
inhibitors of other metabolic processes - disrupt cell respiration
53
standardization
optimizes bacterial growth so inhib of growth can be attributed to antimicrobial
optimizes conditions for maintaining antimicrobial integrity and activity - failure to inhib growth from bacterial resistance
maintains reproducibility and consistency in resistance profile
54
standardized components
inoculum size, growth medium ( mueller hinton - non selective non differential allow growth of wide range of bacteria) pH neutral, cation conc, blood and serum supplements depends on type of bacteria, thymidine content needed for DNA, incubation temp, humidity, duration, antimicrobial conc
55
Standardization in Kirby Bauer procedure
bacterial suspension, conc of antibiotics in discs (provided from manufacturer), incubation time and temp, agar medium (Mueller Hinton)
56
selection of antimicrobial agents for lab testing
organism identification: antimicrobials the bacteria is resistant against are excluded
acquired resistance patterns common to the local microbial flora
site of infection: only achieve effective levels in the urinary tract not be included for other body sites
57
antibiogram
summary report of antimicrobial susceptibility testing from pts
trends in antibiotic resistance within healthcare facility or geographic region
max is 100%
58
dangers of indiscriminate use
changes in the normal flora of the body may --> superinfection due to overgrowth of drug resistant organisms
direct drug toxicity
dev of drug resistance through elim of drug sensitive microbes from antibiotic saturated env (hospitals) and replaced by resistant microbes
59
biological resistance
changes that result in reduced susceptibility of an organism to a particular antimicrobial agent - ongoing process - inability to detect resistance with current lab procedures shouldn't be misinterpreted as evidence no changes in biological resistance
60
clinical resistance
susceptibility is lost to an extent that the drug is no longer effective for clinical use
61
environmentally mediated resistance
directly resulting from physical or chem characteristics of the environment that either directly alter the antimicrobial agent or alter the microbes normal physiologic response to the drug
temp, humidity, inc pH, anaerobic atmosphere, cation conc, thymidine content
aminoglycoside is affected by the absence of oxygen and the conc of cations in the env
tetracycline act dec with inc pH
erythrmicin and aminoglycoside dec with dec pH
gentamycin more effective at neutral and higher pH
oxacillin more effective at lower pH lower MIC = more effective
62
micro-organism mediated resistance
result from genetically encoded traits of the microbe - intrinsic (normal genetic structural or physiologic state of the microbe) or acquired (altered cell physiology caused by changes in genetic make-up)
63
intrinsic resistance
natural - consistently inherited associated with strains of certain bacteria predictable helps in microbe identification and selection of antimicrobials
eg. vancomycin doesn't penetrate the gram neg cell outer membrane
64
acquired resistance
involves genetic changes or exchange - horizontal gene transfer NOT vertical
mutations
resistance genes on plasmids or transposons
65
conjugation
pili attaches to another bacterial cell and allows transfer of genetic material
plasmids - circular DNA introduced into bacteria to express gene interested in
66
transduction
bacteriophage passess DNA from virus to bacteria
67
transformation
takes up donor DNA - Expose to elevated and cold temp - shock therapy
Transient pore bigger to allow introduction of exogenous DNA
Electricity pores open bigger allow to enter and then close again
68
resistance to beta-lactams
enzymatic destruction: beta lactamases open the antibiotic ring and prevents binding to penicillin-binding proteins and cell wall synthesis continues
altered target: changes or acquires genes that encode altered cell wall synthesizing enzymes (penicillin binding proteins) continue function even with b lactams eg s auerus altered PBPS
decreased uptake: gram neg bacteria changes in outer mem porins - p aeruginosa and imipenem
69
resistance to aminoglycosides
enzymatic modifications: alter sites on the AG molecule (phosphorylation or adenylation of hydroxyl groups or acetylation of amine groups) dec affinity for binding to 30S ribosome so protein syn continues
altered target: mutational changes in ribosomal binding site
dec uptake: changes in outer mem porins through which AG pass
70
resistance to glycopeptides
vancomycin in enterococci - rarely staph and never in strep
MOA - bind amino acids in the cell wall to prevent addition of new units to peptidoglycan
production of altered cell wall precursors that don't bind to vancomycin so no inhib of peptidoglycan
71
residential microflora
cause no harm help prevent adherence of pathogenic organisms
coagulase neg staphylococci (epidermis, saprophyticus)
corynebacterium
lactobacilli
some women carry strep agalactiae can pass to neonates (bacteremia, sepsis, meningitis, pneumonia)
72
dysuria
painful urination
N gonorrhea, chlamydia trachomatis and herpes simplex virus
73
urethritis
infection of urethra inflammation
frequent/urgent need to urinate pain urinating discharge
N gonorrhea or non-gonococcal (C trachomatis, trichomonas vaginalis mycoplasma genitalium)
74
vaginitis
abnormal discharge, offensive odor or itching
vaginal candidiasis, bacterial vaginosis, trichomoniasis
75
vaginal candidiasis
fungal infection not STI bc could be naturally found in the body but can be transmitted to sexual partners
usually endogenous origins
itching burning with pee thick cheesy discharge maybe asymptomatic sex allows to grow more rapidly and antibiotics
76
trichomoniasis vaginalis vaginitis
protozoan parasite - frothy offensive off white or yellow green discharge itching
considered STI can be asymptomatic
77
bacterial vaginosis
gardnerella vaginalis - polymicrobial origins and other facultative/anaerobic organisms
not STI but sex is risk factor controlled by lactobacillus and acidic env
milder itch foul smelling discharge fishy maybe asymptomatic
78
syphilis
treponema pallidum
spirochete with motility cant be cultured in vitro
visualized by immunofluorescent stain or dark field microscopy (field dark but image white)
79
treponema pallidum transmission
sexual and vertical (in utero from infected pregnant mother via hematogenous spread to fetus)
primarily contagious to sex partners during primary and secondary stages when infectious lesions or rash are present
bacteria laden sec may transfer the organisms during any type of intimate contact esp of skin abrasions
80
T pallidum virulence factors
dont possess common virulence factors (capsule protein M, fimbriae, enzymes)
outer membrane proteins: 100-x less membrane spanning protein than typical gram neg bacteria
TROMPs (T pallidum rare outer membrane proteins)
common proteins replcade with TROMPs
specific surface antigens antigenically inert antigenic variation of outer membrane protein (TprK) may aid in immune evasion
81
T pallidum pathogenesis
penetration: enters the body via skin and mucus membranes through macroscopic and microscopic abrasions during sex
also transplacentally from mother to fetus during preg
dissemination: before clinical sx, (1st hrs to days after infection) accesses the circ system including lymphatic and regional lymph nodes - invasion of CNS can occur during any stage of symphilis
82
syphilis clinical manifestation
primary
spirochetes multiply locally at site of entry and some spread to nearby lymph nodes and reach the blood stream
within 2-10 weeks after infection s small painless hard lesion (CHANCRE) develops at entry point of bacteria where T pallidum proliferates sensitizes lymphocytes and activates macrophages
inguinal lymphadenopathy seen at this stage
highly infectious spontaneously heals in 1-6 weeks
83
syphilis clinical manifestation
secondary
within sev weeks (2-8) after the primary stage and may overlap
sore throat, HA, mild fever malaise, myalgia, lymphadenopathy and widespread rash doesn't hurt or itch may persist for months
condylomata lata - moist heaped wart like papules that occur in warm intertriginous areas (gluteal folds perineum perianal) lesions v infectious
84
syphilis clinical manifestation
latent syphilis
host suppresses the infection so no lesions clinically apparent
pos serologic test only evidence
no sx may be brief (1 yr range 5-20yrs) when relpases in secondary stage no longer occur pt not contagious through contact
possibility may pass to dev fetus -> miscarriage, stillbirth or congenital syphilis
85
syphilis clinical manifestation
tertiary
granulomatous lesions (gummas) in the skin bones liver or CV lesions
early as 1 yr or 10-30 yrs after primary infection
neurosyphilis occur when bacteria invade nervous system
86
syphilis treatment
first line: penicillin for all 4 stages no reported resistance
second line: macrolides (azithromycin, clarithromycin, erythromycin) resistant strains have been reported
87
non-treponemal tests
screening tests for syphilis
detect reagin (mix of IgM and IgG antibodies against antigens non specific for T pallidum
rapid plasma reagin (RPR) and toluidine red unheated serum tests (TRUST)
anti-lipoidal antibodies - antibodies against cardiolipin
body produces cardiolipin when cell becomes damaged use anti-lipoidal antibodies to identify whether or not cardiolipin in the body and chance have syphilis but not only dx that produces cardiolipins
antibodies against cardiolipin = reagin
follow the efficacy of therapy failing titer = favourable response
quantitative results - 2 fold dilutions
not v sensitive in certain stages (early primary late latent and tertiary)
false pos results can occur with other diseases
revert to neg with time after effective tx
88
treponemal tests for syphilis
measure antibodies directed against T pallidum antigens; includes TP-PA (T pallidum particle agglutination) EIA immunoassays
confirmatory test to determine if pos result from non-treponemal test is truly pos
more specific but hard to detect antibody
little value in monitoring bc once positive after initial infection the tests remain pos for life
trop + non trop - follow up with PCR
89
chancroid
painful ulcer of the skin mucosa of the genitalia with lymphadenopathy
soft painful genital ulcers - soft chancres
form at site of infection similar to syphilitic lesions (primary stage) but syphilitic lesions are usually hard and painless
caused by H ducreyi
gram stain and culture on special media - dies rapidly outside human host
90
genital warts
benign growths of the epithelium range in size from undectable to giant called condylomata acuminate
STI caused by HPV 6,11,16,18
types 16 and 18 associated with cervical cancer - vaccine
91
typical bacterial causes of pneumonia
S pneumoniae, H influ, S aureus, GAS, M cat and aerobic gram neg bacteria
very sick
92
atypical bacterial causes of pneumonia
legionella spp, mycoplasma pneumoniae, chlamydia pneumonia
walking pneumonia
sx not as sev
93
Klebsiella pneumoniae
found in normal flora intestine mouth skin
infections seen in those w debilitating dx - DM, alcoholism
destruction of alveoli --> production of thick bloody sputum
prominent capsule and lactose fermenter
94
mycoplasma pneumoniae
community acquired atypical pneumonia - walking pneumonia
lacks cell wall
pleomorphic cells
cells bound by triple layer unit membrane that contains sterol (mycoplasma require the addition of serum or cholesterol to medium to produce sterols for growth)
attachment mediated by specific adhesion protein
95
chlamydia pneumoniae
spread in resp droplets most infections mild - malaise and cough
obligate intracellular pathogen - must infect another cell to reproduce outer cell wall resembles gram neg bacteria
high lipid content rigid but doesn't contain typ bacteria PG - genes needed for PG synthesis
form small resistant bodies called elementary bodies - infectious agents
96
viral pneumonia
influenza A and B, respiratory syncytial virus, parainfluenza, coronavirus, adenovirus
can be primary cause of pneumonia or major contributing factor that predispose pt to secondary infection by another pathogen
flu a: sig dix, injects humans and bird
flu B: more common mild or seev in high risk pts infects only humans
Flu C: infects humans and pigs
97
community acquired pneumonia in children
strep penumoniae, GAS, H flu, atypical (more common in school age - mycoplasma pneumonia, chlamydophila pneumoniae)
98
community acquired pneumoia in adult
strep pneumo
H flu
M cat, mycoplasma pneumoniae, influenza virus
atypical: chlamydophila pneumoniae
99
hospital acquired penumonia
dev >48 after hospital admin
gram neg bacillus, S aureus, MRSA and multidrug resistant pathogens
100
ventilatory acquired pneumonia
arises >48-72 hr after intubation gram neg bacillus, S aureus, MRSA and multidrug resistant pathogens
101
healthcare acquired pneumonia
hospitalized for >2 days within preceding 90 days
resided in nursing home or LTC facility
in preceding 30 days received IV antibiotic, chemo or wound care
gram neg bacillus, S aureus, MRSA and multidrug resistant pathogens
102
blood culture in pneumonia
obtained from pts with host factors that make it difficult to clear bacteremia (cirrhosis, asplenia, complement deficiencies, leukopenia require hospitalization due to mod or sev bacterial CAP and children who fail clinical improvement
fail to detect mycoplasma pneumonia and viral causes
false neg - preculture antibiotics
false pos due to contamination or extrapulmonary source
103
anti-adherence factors
glycosamine - epithelial layer of bladder prevents bacterial adherence
Tamm-Horsfall protein (uromodulin) produced in kidneys and sec into urine to prevent bacterial adhesion elim more easily
lactobacillus in vag flora
estrogen level - low levels associated with recurrent UTIs
104
microbial flora of urethra
coagulase neg staph, lactobacilli, diphtheroid
pathogens: gram neg aerobic bacilli (enterobacteriaceae) and occasional yeasts
105
etiological agents in UTI
community acquired uncomplicated - single pathogen
complicated can be multiple organisms
E coli - most common
Enterobacteriaceae - klebsiella, proteus, psuedomonas and gram pos more common in complicated pts
stap saprophyticus (coagulase neg)
enterococci - most common gram pos
candida (catheterized, diabetic, hospitalized)
106
uropathogenic E coli virulence factors
fimbriae - adhesion
hemolysin - cytotoxic protein that lyses wide range of cells including PMNs and monocytes
107
acute urethral syndrome
symptomatic abacteriuria
showing sx but NO bacteria
sex active women who experience dysuria and frequency
fewer than 10^5 CFU/ml organisms or steril
pyruria: presence of WBC instead of bacteria - could be UTI but cant culture bacteria (vvirus or anaerobic) or physical abnormality causing sx not UTI or irritation from soaps etc don't misdiagnose
108
sterile pyuria
presence of WBC without bacterial growth on culture from urine
chlamydia, trichomonas, virus (adenovirus or herpes) anaerobic bacteria
kidney disease or autoimmune dx
109
non-enveloped icosahedron shape
adenovirus - URT infection tonsilitis throat cultures needed
rhinovirus - common cold
110
enveloped virus
DNA viruses
RNA viruses
retroviruses
glycoproteins on the surface allows binding to receptors on host cell membrane
111
yeasts
single celled fungi usually reproduce by budding
112
mold
multicellular form of fungi (hyphae)
113
hyphae
tubular branching filaments of fungal cells - mold form of growth may be septate or non septate
114
dimorphic fungi
2 growth forms mold and yeast under dif growth conditions
115
conidia
asexual reproduction which may be formed on a specialized hyphae called conidiophores
116
blastoconidia
budded cell from mother yeast cell
117
arthroconidia
fungal spore formed by segmentation of hyphal cells
118
chlamydoconidia
round thick-walled structures that may be born on the terminal end of hyphae or along its course - can be larger than hypha itself
119
phialoconidia
conidia that are produced by a vase shaped structure cell termed phialide
120
sporangiospores
spores formed on the inside of a specialized fruiting structure
121
pityriasis versicolor - tinea versicolor
superficial mycoses
skin infection - hypo or hyperpigmentation
malassezia furfur
lipophilic yeasts - treat with 20% KOH or calcofluor white
short unbranched hyphae and spherical cells
fluoresce under woods lamp
122
tinea nigra
superficial mycoses
lesions of skins - dark discolouration often on palm
exophiala werneckii
branched septate hyphae and budding yeast cells with melanized cell walls
123
piedra
superficial mycoses
infection of hair shaft produces hair breakage 0 white and black
124
dermatophytosis (ringworm)
cutaneous mycoses
keratinized tisses (skin hair nails)
micrsporum, trichophyton, epidermophyton
125
tinea capitis
infection of scalp and hair
dermatophytosis
126
tinea barbae
acute or chronic folliculitis of the beard/mustache hair area
dermatophytosis
127
tinea corporis
infection of non hiary smooth skin
dermatophytosis
128
tinea cruris
jock itch - acute or chronic fungal infection of groin
dermatophytosis
129
tinea pedis
athletes foot
occurs as chronic infection of toe webs
dermatophytosis
