Identification of Infectious Diseases Flashcards

1
Q

what are the most commonly reported health conditions?

A

-hypertension
-arthritis
-heart disease
-cancer
-diabetes

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2
Q

what is the difference between malnutrition and undernutrition?

A

malnutrition: imbalance of nutrients and stores compared to requirements.

undernutriention: chronic inadequate intake of nutrients which causes severe weight loss

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3
Q

what are some considerations before introducing a new antimicrobial?

A

-renal and hepatic function
-infection site
-administration route
-mode of excretion of the antimicrobial
-potential toxicity of the agent
-allergy history

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4
Q

interpreting and evaluating lab testing is improtant for what?

A

-determining the diagnosis of infection
-assessing the stage of infection
-evaluating HAIs

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5
Q

define accuracy

A

proximity of the result to the true value described by sensitivity and specificity

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6
Q

define sensitivity

A

the ability of a test to detect all true cases (the absence of false negative results)

SNOUT: when negative rules a disease OUT

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7
Q

define specificity

A

the ability of a test to correctly identify a negative result when the disease is absent or the absence of false-positive results

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8
Q

define precision

A

how consistent the results are when a sample is tested repeatedly

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9
Q

define susceptibility

A

how successful an organism is to be treated by an antimicrobial

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10
Q

what do diagnostic tests detect?

A

-antigens in products that result from an infectious agent
-ab immunological response (antibody) to the infecting agent
-the presence of an agent through nucleic acid hybridization and amplification techniques

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11
Q

what are some common lab tests done in LTC facilities?

A

-urinalysis
-WBC
-NAAT/PCR
-antibody detection
-antigen detection

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12
Q

when is an AFB stain used?

A

to identify bacteria with a waxy material in their cell wall (mycobacterium)

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13
Q

what are cultures used to grow?

A

yeast and abcteria

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14
Q

what can a culture yield?

A
  1. polymicrobial growth: more than one type of bacteria cultivated in culture
  2. pure culture: single bacterial strain cultivated in culture
  3. no growth: no bacteria recovered from clinical specimen
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15
Q

when clinically significant the growth on the cultures may be:

A

-quantified
-semi quantified
-non quantitative

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16
Q

antibodys (or immunoglobulins) are produced against a foreign antigen by what?

A

B lymphocytes

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17
Q

once produced, where do antibodies circulate?

A

in blood, secretions, or lymphatic fluid

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18
Q

how can antibody detection results be reported?

A

-qualitatively: positive or negative (antibodys present or not)
-quantitatively: titers (volume of antibodys)

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19
Q

how does antibody testing work?

A

it is a indirect method of identifying infection by assessment of the host response (antibody production) to the bacteria or virus

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20
Q

what are antigens?

A

proteins on the outside of the virus or bacteria that stimulate the human immune system to produce antibodies

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21
Q

when are antigens tests helpful?

A

-early diagnosis (when cultures are not yet positive or possible)
-methods are designed to detect the entire or part of the antigen

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22
Q

true or false. urinarlysis is frequently done to assess general health

A

true

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23
Q

what is tested in basic urinarilsis?

A

-color and clarity, presence of proteins, glucose, ketones, blood, nitrities, and leukocyte esterase
-RBC, WBC, casts, crystals, bacteria or yeast

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24
Q

what are two types of WBC tests used for diagnosing infections?

A

-counting total number of WBC per one cuber millimeter of blood
-leukocytosis (increased WBC in response to bacteria)

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25
Q

define asymptomatic bacteriuria

A

urine is colonized and always grows bacteria even without symptoms

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26
Q

the recovery of how many species in urine generally indicates contamination through faulty collection or delay in transport tot he facility?

A

3 or more

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27
Q

how much poop gets collected?

A

a small amount the size of a loonie or until fluid line

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28
Q

specimens for c.diff testing must be liquid stool type what?

A

6 or 7 (takes the shape of the container)

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29
Q

which areas can you swab for MRSA>

A

anterior nares, perianal area, skin lesions, wound, incisions, ulcers and exit sites of indwelling devices

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30
Q

Which areas can you swab for VRE?

A

stool or rectal/swab from colostomy sites

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31
Q

Where would you swab for group A strep?

A

throat swab

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32
Q

how would you collect a wound swab?

A

-clean wound bed with saline to avoid contamination of the culture by surface organisms
-do not swab exudate or pus
-test the wound base

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33
Q

what swab would you do for pertussis

A

whooping cough

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34
Q

when should an NPS be collected?

A

as early as possible after symptom onset

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35
Q

what are some transportation guidelines for specimens?

A

-all specimens must be transported preferably within 2 hours of collection
-transport in a container designed to ensure survival of suspected agents
-materials for transport must be labelled properly, packaged, and protected during transport

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36
Q

Some sample should not be refigerated as they may contain microorganisms sensitive to extreme temperatures. What are some examples of samples that should not be refigerated?

A

-spinal fluid
-genital
-eye
-internal ear specimens

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37
Q

Which has no nucleus, Prokaryotic or eukaryotic

A

prokaryotic

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38
Q

define bacteria

A

free living, single-celled organisms that multiply through chromosonal replication and cellular division

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39
Q

what are some components of gram negative bacteria?

A

-thin pepridogylcan layer in cell wall
-lipopolysaccharide membrane
-produce endotoxins
-stained red/pink by gram stain
-more resistant to antibiotics

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40
Q

what are some components of gram positive bacteria?

A

=thick peptidoglycan layer in cell wall
-no lipopolysacchride membrane
-produce exotoxins
-stained purple by gram stain
-more susceptible to antibiotics

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41
Q

how can bacteria be organized?

A

-clusters
-chains
-pairs

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42
Q

what are some spirilla gram negative bacteria?

A

campylobacter spp
helicobacter pylori

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43
Q

what is a cocci gram negative bacteria?

A

Nisseria meningitidis

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44
Q

what are some gram negative bacilli?

A

legionella
pseudomonas
E coli
enterobacteriaxeae
salmonella
klebsiella
acinetobacter
proteus
enterobacter
serratai

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45
Q

what are some gram positive bacilli?

A

clostridium
bacillus
listeria

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46
Q

what are some gram positive bacteria

A

-enterococci: appears in chains and pairs (may be VRE)
-staphylococci: appears in clusters (MRSA)
-streptococci: appears in chains (GAS)

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47
Q

define flora

A

microbes that normally live in and on the body without causing infections or disease

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48
Q

what are the 2 types of flora?

A
  1. transient: colonize skin and mucosa temporarily, without invading tissues, when humans come into contact with the environment containing these organisms.
  2. Resident: always present on the skin and body
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49
Q

true or false. Flora that are commensal in a certain area of the body may be pathogenic in another area

A

true

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50
Q

which viruses are easier to kill enveloped or non-enveloped?

A

enveloped

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51
Q

immunocomprimised people are most often infected by what fungi?

A

candida albicans

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52
Q

Define parasite

A

an organism that lives on or within another organism and obtains an advantage at the hosts expense

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53
Q

Which parasites are important in LTC?

A

-parasites that cause GI (undercooked or contamianted food)
-skin infections (louse, bed bugs)

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54
Q

what are 5 principles of pathogenicity?

A

-virulence
-infectivity
-pathogenicity
-duration of exposure (length of time a person is exposed to an orgaism)
-size of inoculum (the number of organisms need to cause disease)

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55
Q

define virulence

A

the ability to invade and create a disease in a host

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56
Q

define infectivity

A

the ability to invade, survive in, and multiply in a host

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57
Q

define pathogenicity

A

the ability of a pathogen to cause disease

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58
Q

what are characteristics of innate immunity?

A

-chemical barriers
-physical barriers
-cellular defences

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59
Q

what are the types of adaptive immunity?

A

-active (natural, vaccination)
passive (maternal, artifical)

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60
Q

what are the properties of immunoglobulins?

A

IgA: late occuring in an immune response and longest lived
IgM: early immune recognition and response; first reacting immunoglobulin
IgA: prevneting viral infections of the respiratory tract and intestinal mucosa
IgE: allergy-inducing immunoglobulin
IgD: function in later immune response

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61
Q

what are some risk factors for developing bacteriuria and a UTI?

A

-age related physiological changes to the GU tract
-neurogenic bladder (MS, PD, Diabetes)
-urinary catheters

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62
Q

define CAUTI

A

UTI where an indwelling urinary catheter (foley) is inserted through the urethra, has been placed in >2 days and the residents develops S&S of a UTI

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63
Q

what is the most common organism isolated from UTIs?

A

e. coli

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64
Q

what are some appropriate uses for urinary catheters?

A

-acute urinary retention or bladder obstruction
-critically ill with need for input and output monitoring
-assist in sacral or perineal wound healing in an incontinent resident
-prolonged immobilization
-end of life comfort

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65
Q

what are some inappropriate uses for urinary catheters?

A

-convenience
-alternative strategies are not utilized
-specimen collection for residents who can void
-catheter is not removed when no longer necessary

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66
Q

insert catheters with ___ technique and ____ supplies

A

aseptic; sterile

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67
Q

true or false. when a CAUTI is suspected, remove the other catheter before obtaining a specimen to prevent contamination by biofilm

A

true

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68
Q

what is pneumonia?

A

inflammatory process of the lung parenchyma caused by a microbial agent

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69
Q

what agents can cause pneumonia?

A

-streptococcus pneumoniiaeae (pneumonococcus) which is a vaccine preventbale disease
-RSV
-Influenza

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70
Q

Influenza ___ viruses are the only Influenza viruses known to cause flu pandemics and most serious illness

A

A

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71
Q

why is the primary method for preventing Influenza and complications?

A

vaccination

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72
Q

what are some pneumonia prevention strategies?

A

-Flu and pneumonococcal vaccinations
-standard precautions
-prevention of oral and respiratory infections
-respiratory therapy equipment maintenance (cleaning CPAP devices on schedule, change humidifer water)

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73
Q

what is Norwegian scabies?

A

aka crusted scabies
a severe form that generally occurs in the immunocomprimsed and may produce less itching

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74
Q

what is scabies?

A

-caused by a parasitic mite
-causes pruritic skin lesion on the hands, webs of finger, wrists knees feet, armpits, butt and waist
-itching is related to allergic reaction

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75
Q

what are the modes of transmission of diarrheal illness?

A

fecal-oral
foodborne
person to person

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76
Q

what are some risk factors for c. diff?

A

antibiotic expsure, PPI, GI surgery, IBD, exposure to healthcare, chronic disease, immunosupression, age over 65 years

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77
Q

what is pseudomembranous colitis?

A

presence of punctate to confluent yellow, white, or gray plaques on the colon surfaceq

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78
Q

CDI is a _____ that produces _____ toxins

A

spore forming bacillus; 2 toxins (A and B). causes diarrhea and colitis in susceptible patients

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79
Q

how can CDI be diagnosed?

A

-stool culture: gold standard for sensitivity but TAT is 7 days
-NAAT: detects c diff toxin, increaaed sens and spef, short tat, costly and should only be used for symptomatic patients
-colon endoscopy: used to detect PMC

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80
Q

what is antimicrobial stewardship for c diff?

A

restrict clindamycin use

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81
Q

how can c diff be cleaned?

A

1:10 dilution of sodium hypocholorite

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82
Q

vaccination is available for which hepatitis strains?

A

A and B

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83
Q

which hep strains are transmitted through blood glucose testing equipment and unsafe injection rpactices?

A

B and C

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84
Q

for can Hep B and C be prevented?

A

-safe injection
-SP
-clean and disinfect blood glucose monitors between uses when shared
-HBV vaccination for hemodialysis residents and those with renal disease that may result in hemodialysis
-screening for hemodialysis residents

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85
Q

antimicrobial resistance is defined as

A

the inability to inhibit or kill the organism with clinically achieveable antimicrobial concentrations

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86
Q

what can cause antimicrobial resistance?

A

-natural (innate)
-acquire (genetic change)
-inadequate treatment 9duration or strength)
-overuse/misuse of AB

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87
Q

what are 3 outcomes of antimicrobial susceptibility testing.

A

susceptible: inhibits bacteria
intermediate: minimal inhibition
resistant: does not inhibit bacteria

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88
Q

what are some MDRO prevention and control methods?

A

-administrative support
-staff education
-judicious use of abs
-surveillance
-contact precautions when infected
-enhanced barrier precautions for MDRO colonization
-environmental measures
-decolonization

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89
Q

signs are ___; symptoms are ___

A

objective; subjective

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90
Q

what characteristics determine virulence?

A

-favored site of invasion
-disease induction
-avoidance of host resistance
-inital element: ability to survive in environment
-second element: mechanism of transmission to a new host

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91
Q

what is an exotoxin?

A

proteins produced in pathogenic bacteria as part of their growtj and metanolism. exotoxins are released in the surrounding medium following lysis

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92
Q

what is an endotoxin?

A

lipid portions of lipopolysaccrides that are part of the outer membrane of the cell wall of gram negative bacteria. liberated when bacteria die and cell wall breaks apart.

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93
Q

are vaccines available for endo or exotoxins? which is more toxic?

A

exotoxins for both

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94
Q

what are components of the cell mediated immune system

A

induced
mediated
regulated by T lymphocutes
mononuclear phagocytes

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95
Q

what are components of the antibody mediated humoral immune system?

A

CD4, CD8 (cytotoxic and suppressive) and B cells
gain the ability to recognize virus infected cells and kills them

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96
Q

what produces antibodies?

A

B lymphocytes

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97
Q

the most immediate SSI is caused by what bacteria?

A

strep pyogenes

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98
Q

what bacterial strcuture faciltitates bacteria implanting on plastc devices?

A

strep pyogenes

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99
Q

NHSN classification of immunocomprimsied includes what

A
  1. those with neutropenia defined as absolute neutrophil count or TWBC <500mm3
  2. those with keujemia, lymphona, or HIV with CD4 count <200
  3. those who have underhone splectomy
  4. history of solid organ or stem cell transplant
  5. cytotoxic chemotherapy
  6. rhose on enteral or parenteral administered steroilds daily for >14 days on the date of event
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100
Q

what are the most important portals of entry for opportunistic organisms?

A

-skin
-oropharynx
-lungs
-GI tract

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101
Q

which opportunistic infections are associated with breaks in skin?

A

staph, strep, corynebacterium, malassezia

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102
Q

which opportunistic infections are associated with defects in mucous membranes

A

-anaerobic bacteria (c perfringens)
-aerobic gram neg bacilli
-enterococcis
-candida
-streptococcus

103
Q

how are clinical manifestations of disease diferent in an immunocomprimised host?

A
  1. patients who are sedated or have CNS dysfunction perceive pain less well and are less likely to articulate problems
  2. neutropenic patients: little purulence at infection site and less obvious chest radiographic findings
  3. elderly patients: confusion or incontinence may be only manifestation of infection
  4. patients on corticosteroids: dimished or absent fever repsonse
104
Q

what are catalase tests and coagulase tests used for?

A

to differentiate between streptococci (negative) and staph (positive)

coagulase: differentative staph aureus from other staph

catalase: bubbles=staph

105
Q

what components of CSF are analyzed?

A
  1. color and clarity
  2. WBCs
  3. protein
  4. glucose
106
Q

what is the causative agent when CSF has elevated white blood cells, increase in protein, and a decrease in glucose

A

bacterial meningitis

107
Q

how do fluroquinolones work?

A

inhibit bacterual enzymes important in DNA replication (cipro)

108
Q

how do macrolides work?

A

inhibit protein synthesis; mostly bacteriostatic therefore used for less serious infection (azithromycin)

109
Q

how do aminoglycosides work?

A

act at the site of bacterial ribosomes. Used for combination therapy for MDROs

110
Q

define the zone of inhibition

A

area in which the concentration of the antibiotic prohibits the growth of the organism

111
Q

how does disk diffusion (kirby-Bauer) susceptibility testing work?

A

-paper disks imprgnant with standard amount of antibitoic are placed onto agar surface
-agar plate is incubated overnight
-organisms growth is either inhibited or not

112
Q

true or false. Some specimens can be placed directly on culture media

A

true

example: genital and blood ultures

113
Q

true or false. routine environmental monitorin could include monthly cultures and endotoxin testing of water and dialysate in hemodialsis units

A

truw

114
Q

whats an example of a specimen that requires immediate transport?

A

CSF

115
Q

how many identifiers are required on the same and req?

A

minimum of 2

116
Q

gram positive cocci in pairs could be what?

A

enterococci or strep pneumoniae

117
Q

results of gram stained are based on what?

A

the amount of peptidoglycan in the cell wall

118
Q

what are the gram stain steps?

A
  1. application of crystal violet
  2. application of iodine
  3. alcohol wash
  4. application of safranin

crystal violet and iodine form a complex that remains in GP bacteria but is removed from GN with decoloization

119
Q

define obligate aerobe and examples

A

needs ozygen to survive

mycobacterium, pseudomonas, bacillus

120
Q

define obligate anaerobe and examples

A

dies in the presence of oxygen

actinemyces, clostridium, bacteroides

121
Q

define facultative anaerobe and examples

A

can function in aerobic and anaerobic but will prefer oxygen most bacteria

122
Q

what are the 3 main types of bacterial and fungal media?

A
  1. Enriched: supports growth for almost all organisms (chocolate agar)
  2. selective enriched: inhibits growth hardy organisms so only selected fastidious organisms grow (legionella CYE agar)
  3. selective and differential: most common type. slective and differentiates the growths that are selected. Hektoen enteric agar
123
Q

what are examples of capnophilic bacteria

A

neisseria gonorrhoeae
campylobacter

CO2 stimulates growth

124
Q

What are examples of bacteria with microaerophillic oxygen requirements

A

campulobacter
helicobacter

requires low but not full oxygen tension

125
Q

how can you do fungal testing?

A

-fungal culture and smear
-presence of pseudo hyphae and hyphae in fungal smear
-can do susceptibility testing when fungas grows
-can test blod for antigens and antibodys but this is specific to the type of fungus

126
Q

what are examples of enveloped viruses?

A

-herpesviruses
-coronaviruses
-orthomyxoviruses (Flu)
-retroviruses (HIV)
-hep b
-orthopox viruses
-heat sensitive and less hardy

127
Q

what are examples of non-enveloped viruses?

A

-adenoviruses, papillomaviruses
-parvoviruses
-reoviruses (rotavirus)
-picornaivurses (polio, coxsackie)

128
Q

what are direct and indirect virus detection methods?

A

direct: virus particles, virus antigen, viral nucleic acids

indirect: serology (test host immune response-IgM)

129
Q

antibody tests are generally done on what type of sample?

A

blood

130
Q

what are some problems with serology testing?

A

-many viruses produce clinical disease before antibody appearance
-long length of time from acute to convalescent era
-immunocomprimised patients have reduced immune response
-patient given blood or blood products might have false positive due to transfer of antibodies

131
Q

what does diagnostic testing for HAV look for?

A

anti-HAV (total antibody: IgM and IgG)

132
Q

when does anti-HAV IgM appear?

A

during accute illness and levels drop over 6-12 months

133
Q

when does anti-HAV IgG appear?

A

later in illness and persists indefintely (protective antibody)

responsible for lifelong immuity to subsequent illness

134
Q

when does the chronic/carrier state for HAV take effect?

A

There isn’t one

135
Q

what is HbsAg?

A

surface antigen; current infection; infectious

136
Q

what is anti-HBC total?

A

persists for life; indicates viral exposure

137
Q

what is anti-HBs>

A

last antibody produced; only vaccine response

138
Q

what is anti-HBc IgM?

A

furst antibody produced; indicates recent infection

139
Q

what is HBeAg?

A

early antigen; indicates recent infection

140
Q

what is anti-HBe?

A

early antibody; appears after anti-HBc IgM but before anti-HBs

141
Q

which hep serologies appear during acute infection?

A

HBsAg
HBeAg

142
Q

what hep serologies appear during early recovery?

A

anti-HBc IgM

143
Q

what hep serologies appear during recovery?

A

anti-HBc
anti-HBs
anti-HBe

144
Q

what does the HBcAg marker mean?

A

exposure

145
Q

what does the HBsAg marker mean?

A

infection

146
Q

what does the HBsAb marker mean?

A

immunity

147
Q

what does anti-HCV indicate

A

presence of antibodies indicates exposure not immunity

148
Q

what is the difference between intrinsic and extrinsic resistance?

A

intrinsic resistance: bacteria and other pathogens are able to develop resistance to abs due to their short reproduction time. Each generation can potentially develop a new way to work around an antibiotic.

acquired resistance: some bacteria acquire the resistance from a different species via plasmid transfer.

149
Q

what antibitoics is MRSA resistant to and what are treatment options?

A

-resistant to most beta-lactams
-carbapenems are a treatment option

150
Q

what antibiotics is VRE resistant to and what are treatment options?

A

resistant to vancomycin and other aminoglycosides. treatment is often ampicillin

151
Q

what antibiotics is ESBL resistant to and what are treatment options?

A

beta lactams

treatments are carbapenems

152
Q

what are examples of CRE?

A

gram neg bacilli with resistance to carbapenems. E. coli, klebsiella pneumoniae, acinetobacter and pseudomonas

153
Q

what are some tests for infectious processes?

A

-complete blood count
-blood cultures
-sedimentation rate
-blood chemistry (liver function tests)
-body fluid analysis
-CRP C-reactive protein
-urinalysis
-toxin producing test

154
Q

what are the major types of WBC?

A

-polymorphonuclear leukocytes (PMNs)

-Mononuclear leukocytes

155
Q

What are examples of PMNs and with what type of infection would you see an increase?

A

-neutrophils, basophils, eosinophils

-increased in bacterial infections

156
Q

What are example of mononuclear leukoytes and with what type of infection would you see an increase?

A

-lymphocytes, monocytes, macrophages
-increased in viral infections

157
Q

what are some symptoms of meningitis?

A

fever, stiff neck, seizures, severe HA, vomiting, confusion

158
Q

what are indicators on a lumbar puncture of viral meningitis?

A

-CSF clear, normal glucose, +/- mononuclear WBCs, no bactiera on gram stain, normal or elevated protein

159
Q

what is the most common source of CSF pathogens?

A

upper respiratory flora (gram negatie bacilli or staph)

s. pneumoniae is most common in adults

160
Q

what pathogen primary causes community acquired pneumonia?

A

s. pneumoniae (uncommon as healthcare-acquired pneumonia)

161
Q

ventilar associated pneumonia or ICU related is often caused by what pathogen?

A

pseudomonas aeruginosa

sometimes stenotrophomonas maltophilia

162
Q

what is the most common pathogen to cause an SSI?

A

staphlococcus

-not usually anaerobes and often caused by skin flora

163
Q

wound infections are often caused by what?

A

skin flora

164
Q

what are some aerobic and anaerobic examples of pathogen that cause deep and organ space SSIs?

A

Anaerobic: bacteriodes fragilis, clostridium, peptostreptococcus

Aerobic: staph, strep, gram neg bacilli

165
Q

in who are UTIs more common (think SAD)

A

-sex (female and sexual activity or pregnancy)
Age: very young males and advanced age
Diabetic
Debilitated (all ages)

166
Q

when are urine results considered significant for UTI?

A

-100,000 CFU/ml with no more than 2 types of bacteria with symptoms

-10,000> but <100.000 with pyuria may indicate infection if symptoms present

167
Q

what is one component of gram postive bacteria now present in gram negative?

A

lipoteichoic acid

168
Q

gram negative contains lipopolysacchrides. Why is this important?

A

because they contain o antigens and lipid A which is important for immunologic response. When our body breaks down gram neg bacteria Lipid A goes into the bloodstream and causes things like fever and septic shock

169
Q

what are calcofluoir white stains used for?

A

binding to chitin in cell walls of fungi

170
Q

what process allows one plasmid to be transferred to another bacterua for resistance?

A

conjugation

171
Q

acquisition of what plasmid can render a bacterium and its descendants immediately resistant if resistance genes are encoded on the plasmid?

A

R plasmid

172
Q

differentiate between transformation, conjugation, and transduction

A

transformation: occurs when naked DNA in the environment, possibly from dead bacteria, enters a bacterium.

Conjugation: occurs when all or part of a plasmid is transferred from a donor to recipient cell. Must be in direct contact and transfer via the sex pilus. Can occur between widely separated species allowing for rapid dissemination of genetic information.

Transduction: when bacterial DNA is transferred from a donor to recipient cell via a virus capable of infecting bacteria

173
Q

are viruses eukarytoic or praokryotic?

A

neither; they are obligate intracellular parasites

174
Q

define virion

A

outside the host cell it is metabolically inert (does not grow or multiply)

175
Q

what are 3 major methods to detect viruses?

A
  1. direct detection in the clinical specimen
  2. specific antibody assay to detect viral antibodies in the serum
  3. viral culture
176
Q

true or false. Fastidious bacteria are hard to grow

A

true

177
Q

what does the choice of media for bacterial cultures depend on?

A
  1. the site being cultured
  2. the growth requirements of common or suspected pathogens
  3. the likelihood of normal flora

choice of nutrients and incubation conditions are critical to growth and identification of bacteria.

178
Q

direct examination or direct wet mount of clinical specimens should be done when after collection?

A

asap

179
Q

what are examples of specimens examined by wet mount?

A

-sputum
-drainage from lesions
-body fluid aspirates
-stool
-vaginal discharge
-urine sediment

180
Q

what are examples of pathogens identified by direct wet mount?

A

motile trophozoites of giardia in stool
trichomonas vaginalis in vaginal discharge or urine sediment
entamoeba hystolitca from a liver abscess aspirate

181
Q

what are 4 types of growth media?

A
  1. nutrient agar
  2. enrichment medium
  3. selective media
  4. differential media
182
Q

what is nutrient agar

A

-supports growth of a wide variety of bacteria
-tryoticase soy agar with 5% sheeps blood

183
Q

what is enrichment medium

A

-contains special nutrients necessary for growth of fastidious bacteria
-chocoalte agar is utilized for neissiria meningitis growth

184
Q

what is selective media

A

-contains chemicals or antibitcs desgined to inhibit normal commensal bacteria

-Bismuth sulfate agar is used for isolating Salmonella

185
Q

what is differential media?

A

stains colonies of specieis organisms, while inhbiting the growth of others

-acetate agar to differentiate E. coi from Shigella

186
Q

what are aerotolerant anerobes?

A

only anaerobic growth but contiues in presence of oxygen

187
Q

what is a microaerophile?

A

only aerobic growth; oxygen is required in low concentration

188
Q

what is the most common HAI?

A

c. diff

189
Q

who had the theory of spontaenous growth?

A

felix archimede pouchet

190
Q

who published micrographia, desribed animalcules, and described bacterial shapes?

A

van Leewenhoek

191
Q

what are some contributes of Robert Koch?

A

-discovered relationship between disease and causative agent anthax, TB, cholera

His postulates:
-pathogen must be present in all cases of a disease
-pathogen must be isolated and grown in culture
-pathogen from pure cultures must cause disease when inoculated in a healthy animal
-same pathogen must be isolated from the diseased lab animal

192
Q

what is the smallest living functional unit of all living organsisms?

A

cell

193
Q

true or false. Prokaryotes lack a nucleus

A

true; example is bacteria

194
Q

what are examples of eukaryotes?

A

-fungus, plant and animals cells

195
Q

true or false. Bacteria have no nuclear membrane but they may have plasmids

A

true

196
Q

how do bacteria reproduce?

A

asexual reproduction

  1. transformation
  2. conjugation
  3. transducation
197
Q

what cell component has a hydrophobic and hydrophillic side composed primarily of phospholipids?

A

the cell envelope (cytoplasmic membrane)

198
Q

what are the main functions of the cell envelope?

A

-transport substances in and out of the cell
-energy production (ETC)-present in all bacteria

199
Q

what is the bacterial chromosome attached to?

A

the plasma membrane

200
Q

plasmids can be transferred from one bacterium to another and genes may move from plasmid to chromosome. what are these genes called?

A

transposable genetic elements or transposons

201
Q

plasmids can carry genes for what?

A

-ab resistance
-toxin production
-synthesis of enzymes

202
Q

bacteria have ____ names

A

binomial; staph is genus name and aureus is the specific epithet

-genus name can be used alone but epithet can not

203
Q

what is the outer membrane of gram negative bacteria composed of?

A

-lipopolysachrides
-lipoproteins
-phospholipids

204
Q

besides mycobacteria, what else is stained by acid-fast?

A

Nocardia

205
Q

which organsisms have to be grown in special enriched broth and agar media and cant be seen using cell wall stains?

A

mycoplasm

206
Q

what is a capsule made of?

A

glycolax (usually polysaccharide)

207
Q

what are the functions of a capsule?

A

-protection from drying out
-protects from toxic materials in the environment
-promotes concentration of nutrients around cells
-adherence
-protects from immune system

208
Q

what are example of organisms that have a capsule?

A

-strep pneumoniae
-n. meningitidis
-hemophilus influenzae

209
Q

why do some bacteria produce endospores?

A

in dormant stage due to nutritional deprivation

210
Q

what is an endospore?

A

-central, terminal, lateral by location
-often resistant to heat, drying, oressure and chemicals (can be autoclave destroyed)
-round or oval shaped structures inside a bacteria

211
Q

what is the epi triad?

A

-agent
-reservoir
-environment

212
Q

define symbiotic

A

neutral: antagonstic or synergistic relationship between two dissimiliar organisms living in close association with one another

213
Q

what are the 4 host-pathogen interactions

A
  1. symbiotic
  2. commensal
    3.. mutualism
  3. parasitic
214
Q

non-specific immunity is also known as

A

innate immunity

215
Q

what is the goal of inflammation?

A

prevent infection setting in
prevent spread of infection or repair damage
mobilize effector cells (T and B lymphocytes)

216
Q

what are the first to appear at the site of injury?

A

neutriphils and eosonophils

217
Q

the adaptive immune system can be broken down into what?

A

humoral and cellular

218
Q

what is humoral immunity?

A

anti-body mediated immunity

with assistance from helper T cells, B cells can produce antibodies against a specific antigen neutralizing them or causing lysis or phagocytosis

219
Q

what is cellular ommunity?

A

occurs inside infected cells and is mediated by T lymphotcytes. Helper T cells release cytokines that help activated T cells bind to infected cells which then undergo lysis

220
Q

what are some gram positive cocci?

A

-strepto
-staphlo
-entero

221
Q

what is a coagulase positive staph?

A

aureus (cause beta hemolysis)

222
Q

what is coagulase negative staph?

A

-epidermidis
-lugdunesis
-non hemolytic

223
Q

most labs are what containment level?

A

2 or 3

224
Q

define containment

A

combination of physical design parameters and operational practices that protect personnel, the immediate work environment, the community, and the external environment from exposure to potentially hazardous biological material

225
Q

describe CL1 and organisms they work with

A

basic lab work area, large scale production area or animal work area. Low hazard organisms like bacillus subtilis, non pathogenic e. coli (schools)

226
Q

describe Cl2 labs and the organisms they work with

A

hostpial settings. Sterile equipment and PPE. Biosafety cabinets to protect from exposure. Pathogens usually spread through injection or ingestion. Herpes, e. coli, salmonella.

227
Q

describe CL3 labs and the organisms they work with

A

negative pressure and HEPA filtration. Purified air and scientists must take showers before exiting. anthraz, TB, West Nile

228
Q

desribe CL4 labs and the organsisms they work with

A

-box within a box. extra alls to prevent breaches. Dedicated breathing air supply and chemical showers to decontaminate. layers of negative pressure zones. Ebola, rabies, measles, gonorrhea, group A strep, shigella, listeria

229
Q

what are agent hazards

A

review potential biological agents and their hazardous characteristics; including capability to infect and cause disease

230
Q

how often are biological risk assessments done?

A

annually

231
Q

what are laboratory procedure hazards?

A

focus on equipment and procedures that generate aerosols, sharps, etc.

232
Q

initial processing of clinical specimens and serological identification of isolates can be done at what containment level?

A

2

233
Q

when should a biological safety cabinet be used?

A
  1. procedures with a potential for creating infectious aerosols or splashes
  2. high concentrations or large volumes of infectious agents used
234
Q

what is essential when transporting biohazardous material?

A

triple containment packaging

235
Q

what are some common critieria for MRSA/VRE screening?

A
  1. hospital admission in the last 12 months
  2. any patient admitted to hospital outside of Canada in the last 12 months
  3. any patient who resides in a communal living setting
  4. previous history of infection/colonization
  5. patients admitted to ICU
236
Q

if swabbing wounds and there is more than one, which one do you swab?

A

the one with the most drainage

237
Q

true or false. If doing a rectal/stoma swab for MRSA or VRE, feces must be visible on the swab

A

true

238
Q

what transport media should be used for c. diff?

A

a container with no media

239
Q

true or false. Cultures are done for c. diff

A

false. specimen is examined for toxin or PCR.

240
Q

how do you test for c. diff?

A

2 step processes. screen for glutamate dehydrogenase antigen and toxins A/B with rapid enzyme immunoassay. Molexular LAMP assay.

241
Q

true or false. Presence of a parasite in any amount is significant.

A

true

242
Q

what are 2 important pieces of information to collect when diarrhea is present?

A
  1. travel history
  2. antibitoic history
243
Q

what is one specimen that must not be frozen?

A

sputum

244
Q

screening tests tend to have high ____ but low _____

A

sensitivty; specificity

245
Q

what are antigens made of?

A

proteins or polysacchrides

246
Q

What are examples of antigen tests?

A

ELISA, immunofluorescence, agglutination tests

247
Q

what pathogens can antigens detect?

A

strep pneumoinae, neisseria meningitidis, group B strep, Hep B, HIV, COVID, Legionella

248
Q

what pathgeosn can be identified by antibody testing?

A

chlamydia, adenovirus, coxsackievirus, Giardia, WNV, Hep A, helicobacter

249
Q

what are examples of molecular diagnostic tests?

A

PCR
1. target amplification methods
2. probe amplification methods
3. signal amplification methods

250
Q

how can measles be diagnosed?

A

NPS
throat swab
urine
CSF

251
Q

what are 4 specimen collection methods for TB?

A

coughing
induced sputum
bronchoscopy
gastric aspiration

252
Q

how are AFB smears graded?

A

-semi quantiative grading system
1+=rare
2+=few
3+=moderate
4+=numerous

253
Q

what is the most sensitive and gold standard for detection of active TB?

A

mycobacterial culture