Identification of Infectious Diseases Flashcards
what are the most commonly reported health conditions?
-hypertension
-arthritis
-heart disease
-cancer
-diabetes
what is the difference between malnutrition and undernutrition?
malnutrition: imbalance of nutrients and stores compared to requirements.
undernutriention: chronic inadequate intake of nutrients which causes severe weight loss
what are some considerations before introducing a new antimicrobial?
-renal and hepatic function
-infection site
-administration route
-mode of excretion of the antimicrobial
-potential toxicity of the agent
-allergy history
interpreting and evaluating lab testing is improtant for what?
-determining the diagnosis of infection
-assessing the stage of infection
-evaluating HAIs
define accuracy
proximity of the result to the true value described by sensitivity and specificity
define sensitivity
the ability of a test to detect all true cases (the absence of false negative results)
SNOUT: when negative rules a disease OUT
define specificity
the ability of a test to correctly identify a negative result when the disease is absent or the absence of false-positive results
define precision
how consistent the results are when a sample is tested repeatedly
define susceptibility
how successful an organism is to be treated by an antimicrobial
what do diagnostic tests detect?
-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
what are some common lab tests done in LTC facilities?
-urinalysis
-WBC
-NAAT/PCR
-antibody detection
-antigen detection
when is an AFB stain used?
to identify bacteria with a waxy material in their cell wall (mycobacterium)
what are cultures used to grow?
yeast and abcteria
what can a culture yield?
- polymicrobial growth: more than one type of bacteria cultivated in culture
- pure culture: single bacterial strain cultivated in culture
- no growth: no bacteria recovered from clinical specimen
when clinically significant the growth on the cultures may be:
-quantified
-semi quantified
-non quantitative
antibodys (or immunoglobulins) are produced against a foreign antigen by what?
B lymphocytes
once produced, where do antibodies circulate?
in blood, secretions, or lymphatic fluid
how can antibody detection results be reported?
-qualitatively: positive or negative (antibodys present or not)
-quantitatively: titers (volume of antibodys)
how does antibody testing work?
it is a indirect method of identifying infection by assessment of the host response (antibody production) to the bacteria or virus
what are antigens?
proteins on the outside of the virus or bacteria that stimulate the human immune system to produce antibodies
when are antigens tests helpful?
-early diagnosis (when cultures are not yet positive or possible)
-methods are designed to detect the entire or part of the antigen
true or false. urinarlysis is frequently done to assess general health
true
what is tested in basic urinarilsis?
-color and clarity, presence of proteins, glucose, ketones, blood, nitrities, and leukocyte esterase
-RBC, WBC, casts, crystals, bacteria or yeast
what are two types of WBC tests used for diagnosing infections?
-counting total number of WBC per one cuber millimeter of blood
-leukocytosis (increased WBC in response to bacteria)
define asymptomatic bacteriuria
urine is colonized and always grows bacteria even without symptoms
the recovery of how many species in urine generally indicates contamination through faulty collection or delay in transport tot he facility?
3 or more
how much poop gets collected?
a small amount the size of a loonie or until fluid line
specimens for c.diff testing must be liquid stool type what?
6 or 7 (takes the shape of the container)
which areas can you swab for MRSA>
anterior nares, perianal area, skin lesions, wound, incisions, ulcers and exit sites of indwelling devices
Which areas can you swab for VRE?
stool or rectal/swab from colostomy sites
Where would you swab for group A strep?
throat swab
how would you collect a wound swab?
-clean wound bed with saline to avoid contamination of the culture by surface organisms
-do not swab exudate or pus
-test the wound base
what swab would you do for pertussis
whooping cough
when should an NPS be collected?
as early as possible after symptom onset
what are some transportation guidelines for specimens?
-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
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?
-spinal fluid
-genital
-eye
-internal ear specimens
Which has no nucleus, Prokaryotic or eukaryotic
prokaryotic
define bacteria
free living, single-celled organisms that multiply through chromosonal replication and cellular division
what are some components of gram negative bacteria?
-thin pepridogylcan layer in cell wall
-lipopolysaccharide membrane
-produce endotoxins
-stained red/pink by gram stain
-more resistant to antibiotics
what are some components of gram positive bacteria?
=thick peptidoglycan layer in cell wall
-no lipopolysacchride membrane
-produce exotoxins
-stained purple by gram stain
-more susceptible to antibiotics
how can bacteria be organized?
-clusters
-chains
-pairs
what are some spirilla gram negative bacteria?
campylobacter spp
helicobacter pylori
what is a cocci gram negative bacteria?
Nisseria meningitidis
what are some gram negative bacilli?
legionella
pseudomonas
E coli
enterobacteriaxeae
salmonella
klebsiella
acinetobacter
proteus
enterobacter
serratai
what are some gram positive bacilli?
clostridium
bacillus
listeria
what are some gram positive bacteria
-enterococci: appears in chains and pairs (may be VRE)
-staphylococci: appears in clusters (MRSA)
-streptococci: appears in chains (GAS)
define flora
microbes that normally live in and on the body without causing infections or disease
what are the 2 types of flora?
- transient: colonize skin and mucosa temporarily, without invading tissues, when humans come into contact with the environment containing these organisms.
- Resident: always present on the skin and body
true or false. Flora that are commensal in a certain area of the body may be pathogenic in another area
true
which viruses are easier to kill enveloped or non-enveloped?
enveloped
immunocomprimised people are most often infected by what fungi?
candida albicans
Define parasite
an organism that lives on or within another organism and obtains an advantage at the hosts expense
Which parasites are important in LTC?
-parasites that cause GI (undercooked or contamianted food)
-skin infections (louse, bed bugs)
what are 5 principles of pathogenicity?
-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)
define virulence
the ability to invade and create a disease in a host
define infectivity
the ability to invade, survive in, and multiply in a host
define pathogenicity
the ability of a pathogen to cause disease
what are characteristics of innate immunity?
-chemical barriers
-physical barriers
-cellular defences
what are the types of adaptive immunity?
-active (natural, vaccination)
passive (maternal, artifical)
what are the properties of immunoglobulins?
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
what are some risk factors for developing bacteriuria and a UTI?
-age related physiological changes to the GU tract
-neurogenic bladder (MS, PD, Diabetes)
-urinary catheters
define CAUTI
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
what is the most common organism isolated from UTIs?
e. coli
what are some appropriate uses for urinary catheters?
-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
what are some inappropriate uses for urinary catheters?
-convenience
-alternative strategies are not utilized
-specimen collection for residents who can void
-catheter is not removed when no longer necessary
insert catheters with ___ technique and ____ supplies
aseptic; sterile
true or false. when a CAUTI is suspected, remove the other catheter before obtaining a specimen to prevent contamination by biofilm
true
what is pneumonia?
inflammatory process of the lung parenchyma caused by a microbial agent
what agents can cause pneumonia?
-streptococcus pneumoniiaeae (pneumonococcus) which is a vaccine preventbale disease
-RSV
-Influenza
Influenza ___ viruses are the only Influenza viruses known to cause flu pandemics and most serious illness
A
why is the primary method for preventing Influenza and complications?
vaccination
what are some pneumonia prevention strategies?
-Flu and pneumonococcal vaccinations
-standard precautions
-prevention of oral and respiratory infections
-respiratory therapy equipment maintenance (cleaning CPAP devices on schedule, change humidifer water)
what is Norwegian scabies?
aka crusted scabies
a severe form that generally occurs in the immunocomprimsed and may produce less itching
what is scabies?
-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
what are the modes of transmission of diarrheal illness?
fecal-oral
foodborne
person to person
what are some risk factors for c. diff?
antibiotic expsure, PPI, GI surgery, IBD, exposure to healthcare, chronic disease, immunosupression, age over 65 years
what is pseudomembranous colitis?
presence of punctate to confluent yellow, white, or gray plaques on the colon surfaceq
CDI is a _____ that produces _____ toxins
spore forming bacillus; 2 toxins (A and B). causes diarrhea and colitis in susceptible patients
how can CDI be diagnosed?
-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
what is antimicrobial stewardship for c diff?
restrict clindamycin use
how can c diff be cleaned?
1:10 dilution of sodium hypocholorite
vaccination is available for which hepatitis strains?
A and B
which hep strains are transmitted through blood glucose testing equipment and unsafe injection rpactices?
B and C
for can Hep B and C be prevented?
-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
antimicrobial resistance is defined as
the inability to inhibit or kill the organism with clinically achieveable antimicrobial concentrations
what can cause antimicrobial resistance?
-natural (innate)
-acquire (genetic change)
-inadequate treatment 9duration or strength)
-overuse/misuse of AB
what are 3 outcomes of antimicrobial susceptibility testing.
susceptible: inhibits bacteria
intermediate: minimal inhibition
resistant: does not inhibit bacteria
what are some MDRO prevention and control methods?
-administrative support
-staff education
-judicious use of abs
-surveillance
-contact precautions when infected
-enhanced barrier precautions for MDRO colonization
-environmental measures
-decolonization
signs are ___; symptoms are ___
objective; subjective
what characteristics determine virulence?
-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
what is an exotoxin?
proteins produced in pathogenic bacteria as part of their growtj and metanolism. exotoxins are released in the surrounding medium following lysis
what is an endotoxin?
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.
are vaccines available for endo or exotoxins? which is more toxic?
exotoxins for both
what are components of the cell mediated immune system
induced
mediated
regulated by T lymphocutes
mononuclear phagocytes
what are components of the antibody mediated humoral immune system?
CD4, CD8 (cytotoxic and suppressive) and B cells
gain the ability to recognize virus infected cells and kills them
what produces antibodies?
B lymphocytes
the most immediate SSI is caused by what bacteria?
strep pyogenes
what bacterial strcuture faciltitates bacteria implanting on plastc devices?
strep pyogenes
NHSN classification of immunocomprimsied includes what
- those with neutropenia defined as absolute neutrophil count or TWBC <500mm3
- those with keujemia, lymphona, or HIV with CD4 count <200
- those who have underhone splectomy
- history of solid organ or stem cell transplant
- cytotoxic chemotherapy
- rhose on enteral or parenteral administered steroilds daily for >14 days on the date of event
what are the most important portals of entry for opportunistic organisms?
-skin
-oropharynx
-lungs
-GI tract
which opportunistic infections are associated with breaks in skin?
staph, strep, corynebacterium, malassezia
which opportunistic infections are associated with defects in mucous membranes
-anaerobic bacteria (c perfringens)
-aerobic gram neg bacilli
-enterococcis
-candida
-streptococcus
how are clinical manifestations of disease diferent in an immunocomprimised host?
- patients who are sedated or have CNS dysfunction perceive pain less well and are less likely to articulate problems
- neutropenic patients: little purulence at infection site and less obvious chest radiographic findings
- elderly patients: confusion or incontinence may be only manifestation of infection
- patients on corticosteroids: dimished or absent fever repsonse
what are catalase tests and coagulase tests used for?
to differentiate between streptococci (negative) and staph (positive)
coagulase: differentative staph aureus from other staph
catalase: bubbles=staph
what components of CSF are analyzed?
- color and clarity
- WBCs
- protein
- glucose
what is the causative agent when CSF has elevated white blood cells, increase in protein, and a decrease in glucose
bacterial meningitis
how do fluroquinolones work?
inhibit bacterual enzymes important in DNA replication (cipro)
how do macrolides work?
inhibit protein synthesis; mostly bacteriostatic therefore used for less serious infection (azithromycin)
how do aminoglycosides work?
act at the site of bacterial ribosomes. Used for combination therapy for MDROs
define the zone of inhibition
area in which the concentration of the antibiotic prohibits the growth of the organism
how does disk diffusion (kirby-Bauer) susceptibility testing work?
-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
true or false. Some specimens can be placed directly on culture media
true
example: genital and blood ultures
true or false. routine environmental monitorin could include monthly cultures and endotoxin testing of water and dialysate in hemodialsis units
truw
whats an example of a specimen that requires immediate transport?
CSF
how many identifiers are required on the same and req?
minimum of 2
gram positive cocci in pairs could be what?
enterococci or strep pneumoniae
results of gram stained are based on what?
the amount of peptidoglycan in the cell wall
what are the gram stain steps?
- application of crystal violet
- application of iodine
- alcohol wash
- application of safranin
crystal violet and iodine form a complex that remains in GP bacteria but is removed from GN with decoloization
define obligate aerobe and examples
needs ozygen to survive
mycobacterium, pseudomonas, bacillus
define obligate anaerobe and examples
dies in the presence of oxygen
actinemyces, clostridium, bacteroides
define facultative anaerobe and examples
can function in aerobic and anaerobic but will prefer oxygen most bacteria
what are the 3 main types of bacterial and fungal media?
- Enriched: supports growth for almost all organisms (chocolate agar)
- selective enriched: inhibits growth hardy organisms so only selected fastidious organisms grow (legionella CYE agar)
- selective and differential: most common type. slective and differentiates the growths that are selected. Hektoen enteric agar
what are examples of capnophilic bacteria
neisseria gonorrhoeae
campylobacter
CO2 stimulates growth
What are examples of bacteria with microaerophillic oxygen requirements
campulobacter
helicobacter
requires low but not full oxygen tension
how can you do fungal testing?
-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
what are examples of enveloped viruses?
-herpesviruses
-coronaviruses
-orthomyxoviruses (Flu)
-retroviruses (HIV)
-hep b
-orthopox viruses
-heat sensitive and less hardy
what are examples of non-enveloped viruses?
-adenoviruses, papillomaviruses
-parvoviruses
-reoviruses (rotavirus)
-picornaivurses (polio, coxsackie)
what are direct and indirect virus detection methods?
direct: virus particles, virus antigen, viral nucleic acids
indirect: serology (test host immune response-IgM)
antibody tests are generally done on what type of sample?
blood
what are some problems with serology testing?
-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
what does diagnostic testing for HAV look for?
anti-HAV (total antibody: IgM and IgG)
when does anti-HAV IgM appear?
during accute illness and levels drop over 6-12 months
when does anti-HAV IgG appear?
later in illness and persists indefintely (protective antibody)
responsible for lifelong immuity to subsequent illness
when does the chronic/carrier state for HAV take effect?
There isn’t one
what is HbsAg?
surface antigen; current infection; infectious
what is anti-HBC total?
persists for life; indicates viral exposure
what is anti-HBs>
last antibody produced; only vaccine response
what is anti-HBc IgM?
furst antibody produced; indicates recent infection
what is HBeAg?
early antigen; indicates recent infection
what is anti-HBe?
early antibody; appears after anti-HBc IgM but before anti-HBs
which hep serologies appear during acute infection?
HBsAg
HBeAg
what hep serologies appear during early recovery?
anti-HBc IgM
what hep serologies appear during recovery?
anti-HBc
anti-HBs
anti-HBe
what does the HBcAg marker mean?
exposure
what does the HBsAg marker mean?
infection
what does the HBsAb marker mean?
immunity
what does anti-HCV indicate
presence of antibodies indicates exposure not immunity
what is the difference between intrinsic and extrinsic resistance?
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.
what antibitoics is MRSA resistant to and what are treatment options?
-resistant to most beta-lactams
-carbapenems are a treatment option
what antibiotics is VRE resistant to and what are treatment options?
resistant to vancomycin and other aminoglycosides. treatment is often ampicillin
what antibiotics is ESBL resistant to and what are treatment options?
beta lactams
treatments are carbapenems
what are examples of CRE?
gram neg bacilli with resistance to carbapenems. E. coli, klebsiella pneumoniae, acinetobacter and pseudomonas
what are some tests for infectious processes?
-complete blood count
-blood cultures
-sedimentation rate
-blood chemistry (liver function tests)
-body fluid analysis
-CRP C-reactive protein
-urinalysis
-toxin producing test
what are the major types of WBC?
-polymorphonuclear leukocytes (PMNs)
-Mononuclear leukocytes
What are examples of PMNs and with what type of infection would you see an increase?
-neutrophils, basophils, eosinophils
-increased in bacterial infections
What are example of mononuclear leukoytes and with what type of infection would you see an increase?
-lymphocytes, monocytes, macrophages
-increased in viral infections
what are some symptoms of meningitis?
fever, stiff neck, seizures, severe HA, vomiting, confusion
what are indicators on a lumbar puncture of viral meningitis?
-CSF clear, normal glucose, +/- mononuclear WBCs, no bactiera on gram stain, normal or elevated protein
what is the most common source of CSF pathogens?
upper respiratory flora (gram negatie bacilli or staph)
s. pneumoniae is most common in adults
what pathogen primary causes community acquired pneumonia?
s. pneumoniae (uncommon as healthcare-acquired pneumonia)
ventilar associated pneumonia or ICU related is often caused by what pathogen?
pseudomonas aeruginosa
sometimes stenotrophomonas maltophilia
what is the most common pathogen to cause an SSI?
staphlococcus
-not usually anaerobes and often caused by skin flora
wound infections are often caused by what?
skin flora
what are some aerobic and anaerobic examples of pathogen that cause deep and organ space SSIs?
Anaerobic: bacteriodes fragilis, clostridium, peptostreptococcus
Aerobic: staph, strep, gram neg bacilli
in who are UTIs more common (think SAD)
-sex (female and sexual activity or pregnancy)
Age: very young males and advanced age
Diabetic
Debilitated (all ages)
when are urine results considered significant for UTI?
-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
what is one component of gram postive bacteria now present in gram negative?
lipoteichoic acid
gram negative contains lipopolysacchrides. Why is this important?
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
what are calcofluoir white stains used for?
binding to chitin in cell walls of fungi
what process allows one plasmid to be transferred to another bacterua for resistance?
conjugation
acquisition of what plasmid can render a bacterium and its descendants immediately resistant if resistance genes are encoded on the plasmid?
R plasmid
differentiate between transformation, conjugation, and transduction
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
are viruses eukarytoic or praokryotic?
neither; they are obligate intracellular parasites
define virion
outside the host cell it is metabolically inert (does not grow or multiply)
what are 3 major methods to detect viruses?
- direct detection in the clinical specimen
- specific antibody assay to detect viral antibodies in the serum
- viral culture
true or false. Fastidious bacteria are hard to grow
true
what does the choice of media for bacterial cultures depend on?
- the site being cultured
- the growth requirements of common or suspected pathogens
- the likelihood of normal flora
choice of nutrients and incubation conditions are critical to growth and identification of bacteria.
direct examination or direct wet mount of clinical specimens should be done when after collection?
asap
what are examples of specimens examined by wet mount?
-sputum
-drainage from lesions
-body fluid aspirates
-stool
-vaginal discharge
-urine sediment
what are examples of pathogens identified by direct wet mount?
motile trophozoites of giardia in stool
trichomonas vaginalis in vaginal discharge or urine sediment
entamoeba hystolitca from a liver abscess aspirate
what are 4 types of growth media?
- nutrient agar
- enrichment medium
- selective media
- differential media
what is nutrient agar
-supports growth of a wide variety of bacteria
-tryoticase soy agar with 5% sheeps blood
what is enrichment medium
-contains special nutrients necessary for growth of fastidious bacteria
-chocoalte agar is utilized for neissiria meningitis growth
what is selective media
-contains chemicals or antibitcs desgined to inhibit normal commensal bacteria
-Bismuth sulfate agar is used for isolating Salmonella
what is differential media?
stains colonies of specieis organisms, while inhbiting the growth of others
-acetate agar to differentiate E. coi from Shigella
what are aerotolerant anerobes?
only anaerobic growth but contiues in presence of oxygen
what is a microaerophile?
only aerobic growth; oxygen is required in low concentration
what is the most common HAI?
c. diff
who had the theory of spontaenous growth?
felix archimede pouchet
who published micrographia, desribed animalcules, and described bacterial shapes?
van Leewenhoek
what are some contributes of Robert Koch?
-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
what is the smallest living functional unit of all living organsisms?
cell
true or false. Prokaryotes lack a nucleus
true; example is bacteria
what are examples of eukaryotes?
-fungus, plant and animals cells
true or false. Bacteria have no nuclear membrane but they may have plasmids
true
how do bacteria reproduce?
asexual reproduction
- transformation
- conjugation
- transducation
what cell component has a hydrophobic and hydrophillic side composed primarily of phospholipids?
the cell envelope (cytoplasmic membrane)
what are the main functions of the cell envelope?
-transport substances in and out of the cell
-energy production (ETC)-present in all bacteria
what is the bacterial chromosome attached to?
the plasma membrane
plasmids can be transferred from one bacterium to another and genes may move from plasmid to chromosome. what are these genes called?
transposable genetic elements or transposons
plasmids can carry genes for what?
-ab resistance
-toxin production
-synthesis of enzymes
bacteria have ____ names
binomial; staph is genus name and aureus is the specific epithet
-genus name can be used alone but epithet can not
what is the outer membrane of gram negative bacteria composed of?
-lipopolysachrides
-lipoproteins
-phospholipids
besides mycobacteria, what else is stained by acid-fast?
Nocardia
which organsisms have to be grown in special enriched broth and agar media and cant be seen using cell wall stains?
mycoplasm
what is a capsule made of?
glycolax (usually polysaccharide)
what are the functions of a capsule?
-protection from drying out
-protects from toxic materials in the environment
-promotes concentration of nutrients around cells
-adherence
-protects from immune system
what are example of organisms that have a capsule?
-strep pneumoniae
-n. meningitidis
-hemophilus influenzae
why do some bacteria produce endospores?
in dormant stage due to nutritional deprivation
what is an endospore?
-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
what is the epi triad?
-agent
-reservoir
-environment
define symbiotic
neutral: antagonstic or synergistic relationship between two dissimiliar organisms living in close association with one another
what are the 4 host-pathogen interactions
- symbiotic
- commensal
3.. mutualism - parasitic
non-specific immunity is also known as
innate immunity
what is the goal of inflammation?
prevent infection setting in
prevent spread of infection or repair damage
mobilize effector cells (T and B lymphocytes)
what are the first to appear at the site of injury?
neutriphils and eosonophils
the adaptive immune system can be broken down into what?
humoral and cellular
what is humoral immunity?
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
what is cellular ommunity?
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
what are some gram positive cocci?
-strepto
-staphlo
-entero
what is a coagulase positive staph?
aureus (cause beta hemolysis)
what is coagulase negative staph?
-epidermidis
-lugdunesis
-non hemolytic
most labs are what containment level?
2 or 3
define containment
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
describe CL1 and organisms they work with
basic lab work area, large scale production area or animal work area. Low hazard organisms like bacillus subtilis, non pathogenic e. coli (schools)
describe Cl2 labs and the organisms they work with
hostpial settings. Sterile equipment and PPE. Biosafety cabinets to protect from exposure. Pathogens usually spread through injection or ingestion. Herpes, e. coli, salmonella.
describe CL3 labs and the organisms they work with
negative pressure and HEPA filtration. Purified air and scientists must take showers before exiting. anthraz, TB, West Nile
desribe CL4 labs and the organsisms they work with
-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
what are agent hazards
review potential biological agents and their hazardous characteristics; including capability to infect and cause disease
how often are biological risk assessments done?
annually
what are laboratory procedure hazards?
focus on equipment and procedures that generate aerosols, sharps, etc.
initial processing of clinical specimens and serological identification of isolates can be done at what containment level?
2
when should a biological safety cabinet be used?
- procedures with a potential for creating infectious aerosols or splashes
- high concentrations or large volumes of infectious agents used
what is essential when transporting biohazardous material?
triple containment packaging
what are some common critieria for MRSA/VRE screening?
- hospital admission in the last 12 months
- any patient admitted to hospital outside of Canada in the last 12 months
- any patient who resides in a communal living setting
- previous history of infection/colonization
- patients admitted to ICU
if swabbing wounds and there is more than one, which one do you swab?
the one with the most drainage
true or false. If doing a rectal/stoma swab for MRSA or VRE, feces must be visible on the swab
true
what transport media should be used for c. diff?
a container with no media
true or false. Cultures are done for c. diff
false. specimen is examined for toxin or PCR.
how do you test for c. diff?
2 step processes. screen for glutamate dehydrogenase antigen and toxins A/B with rapid enzyme immunoassay. Molexular LAMP assay.
true or false. Presence of a parasite in any amount is significant.
true
what are 2 important pieces of information to collect when diarrhea is present?
- travel history
- antibitoic history
what is one specimen that must not be frozen?
sputum
screening tests tend to have high ____ but low _____
sensitivty; specificity
what are antigens made of?
proteins or polysacchrides
What are examples of antigen tests?
ELISA, immunofluorescence, agglutination tests
what pathogens can antigens detect?
strep pneumoinae, neisseria meningitidis, group B strep, Hep B, HIV, COVID, Legionella
what pathgeosn can be identified by antibody testing?
chlamydia, adenovirus, coxsackievirus, Giardia, WNV, Hep A, helicobacter
what are examples of molecular diagnostic tests?
PCR
1. target amplification methods
2. probe amplification methods
3. signal amplification methods
how can measles be diagnosed?
NPS
throat swab
urine
CSF
what are 4 specimen collection methods for TB?
coughing
induced sputum
bronchoscopy
gastric aspiration
how are AFB smears graded?
-semi quantiative grading system
1+=rare
2+=few
3+=moderate
4+=numerous
what is the most sensitive and gold standard for detection of active TB?
mycobacterial culture
