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Clinical Laboratory Science > Clincal Microbiology > Flashcards

Clincal Microbiology Flashcards

(69 cards)

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1
Q

What are the characteristics of bacteria

A

Multiply by fission
Form colonies
Bacteria morphology

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2
Q

Bacteria Shapes

A

Coccus
Bacillus
Spirochetes

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3
Q

Types of Gram stains

A

Gram positive appear blue-purple,
gram negative appear pink-red

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4
Q

Growth requirements

A

Medium provides nutrients for growing
microorganisms
○ Bacteria that can only grow on
specialized medium are fastidious
bacteria
○ Aerobic and anaerobic bacteria

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5
Q

what is Pathogens

A

bacteria that
cause disease through
infection

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6
Q

what is communicable disease

A

Diseases that spread from
person

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7
Q

Normal flora

A

bacteria
that are natural inhabitants
of the human body

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8
Q

Opportunistic pathogens

A

invade the body only
when immune defenses are
impaired

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9
Q

Bacteriological Procedures

A

Specimen collection
- Bacteria collected
- Find growth of
bacteria on a medium that
provides nutrients
Identifying bacteria
- can use Microscopic morphology, colony
appearance, reactions with Gram
stain, growth on media,
biochemical reactions, gene
probes, antibody reactions
Antibiotic susceptibility testing
- Find minimum inhibitory
concentration (MIC)

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10
Q

Reasons for Ordering Cultures

A

bad Throat
- Sore throat, fever, negative
rapid strep test

bad Nasal
- B Pertussis, MRSA,
rhinovirus, flu, RSV

bad Urine
- Recurring UTIs

bad Sputum
- Prolonged cough, fever, lung
infection, TB, pneumonia

bad Stool
- Diarrhea with blood and mucous,
prolonged bout of diarrhea
Signs of intestinal infection,
Salmonella, E. coli

bad Blood
- Suspected sepsis or
septicemia

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11
Q

throat culture

A

If negative for rapid test for strep throat, perform throat culture
● Sterile swab should be touched to tonsils or pharyngeal surfaces; tongue and
mouth will contaminate swab
● Streak immediately on blood agar plate if available

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12
Q

Nasal Culture

A

Nasopharyngeal swabs with flexible shafts, moistened with sterile saline; one
swab for each nasal cavity
● Swab inserted into anterior nostril 2 cm and rotated gently against nasal mucosa
● No rayon/Dacron swabs because they kill target organisms
● If pertussis (whooping cough) suspected, calcium alginate swab used with
Regan-Lowe medium transport

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13
Q

Urine Culture

A

Clean-catch collected in sterile container
● If urine can’t be cultured within an hour after collection, use sterile tube such as
BD Urine C&S Transport kit

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14
Q

Sputum Culture

A

Sputum is material coughed up from lungs and is examined to aid in diagnosis
of lower respiratory tract infection
● Collection instructions
○ Rinse mouth
○ Collect 2 separate specimens in sterile containers, such as BD Sputum
Collection System

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15
Q

Stool Culture

A

One specimen per day collected on 3 consecutive days
● 3 vials that contain medium such as Cary Blair or Amies
● Para-Pak vials for culture

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16
Q

Blood Culture

A

Collected by venipuncture; site must be cleansed first with alcohol then with a swab
containing 2% solution of tincture of iodine
● In order of draw, blood culture bottles are filled first; 2 bottles usually collected, aerobic bottle
filled first
● Bactec instrument inoculated blood cultures and senses changes in CO2, which is released as
microorganisms grow; smear of blood from positive bottle can be made and Gram-stained to
determine microorganism present
● Trek Diagnostic ESP EZ Draw draws 0.1 mL of blood

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17
Q

Aseptic technique

A

set of procedures used to prevent spread of infection during surgical
procedures

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18
Q

Aseptic technique (physical)

A

○ Protective clothing
○ Fluid-resistant lab coat
○ Disposable lab coats/gowns

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19
Q

Microbiological safety cabinets

A

Class I – protect worker and environment but not culture
Class II – provide protection to worker, environment, and culture

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20
Q

Disinfectants and antiseptics

A

Disinfectants are chemicals used to kill/control growth of microorganisms or inanimate objects
Bactericidal – kill bacteria
Bacteriostatic – slow growth of bacteria
Antiseptics are chemicals used to control growth of microorganisms on living tissue
Sterilization frees an article or area from all living organisms

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21
Q

Agar

A

derivative of seaweed used to solidify liquid
media, which grows and isolates bacteria

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22
Q

Primary medium

A

first inoculated with
specimen collected from patient
○ Most common is blood agar

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23
Q

Enriched medium

A

supports growth of
wide variety of organisms

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24
Q

Selective media

A

ingredients that inhibit the
growth of certain microorganisms while allowing the
growth of others

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25
Indicator medium
detects metabolic activity of particular microorganisms
26
Inoculation
Process of transferring microorganisms to a growth medium
27
How to do swab agar plate
Gently roll specimen swab onto one quadrant of agar plate, then prep bacterial smear by rolling swab across sterile glass slide ○ Inoculating loop spreads inoculated material over agar plate to produce isolated colonies ○ Accomplished by streaking 4 quadrants, decreasing amount of culture material as streaking proceeds into each quadrant ○ Loop Is sterilized and cooled to spread material into each quadrant
28
Incubation
Usually kept in 35-37 C incubator ● Plates are inverted to prevent formation of condensate inside lid ● For aerobic specimens, keep lid open a little bit and incubate in aerobic incubator (ambient air) ● Pathogens that grow in CO2 are kept in CO2 incubator with 5-10% CO2 ● Anaerobic specimens can be incubated in sealed bags/containers
29
What to do after Observation After 24 Hours
Growth on blood agar should be observed for hemolysis, the lysis of RBCs by bacteria growing on blood agar
30
Beta hemolysis
completely lyses blood cells and makes surrounding area transparent
31
Alpha hemolysis
incompletely lyses RBCs and makes area green
32
how to do Gram stain
○Primary stain ■ Crystal violet poured on slide ■ All bacteria stain purple ○ Gram's iodine ■ Gram's iodine, a mordant, allows dye to adhere ■ All bacteria remain purple ○ Decolorizer ■ Alcohol added briefly to slide when it is tilted downward at 30 degrees ■ Gram-negative bacteria will be colorless ○ Counterstain ■ Slide flooded with counterstain safranin ■ Gram-negative bacteria turn pink
33
Performing the Throat Culture
Collecting the specimen ○ Pharyngeal surfaces swabbed with sterile Dacron/rayon swab; passed across surfaces of both tonsils or surfaces of fossae and back of throat ○ Don't touch tongue or inside of mouth ● Inoculating the media ○ Throat swab immediately used to inoculate a quadrant of the blood agar plate ○ Paper disk with antibiotic bacitracin can be placed on concentrated streak in 1st quadrant ● Incubating the culture ○ CO2 concentration of 10% ● Reading throat culture plate ○ Beta hemolysis should show up in stabs ○ Presence of zone of inhibition around bacitracin disk and presence of beta-hemolytic colonies shows Group A Strep
34
Why are urine cultures collected?
Culture requested when patient has UTI symptoms
35
What contributes to STDs?
Escherichia coli - gram-negative rod part of flora of intestinal tract
36
How to perform urine culture
Clean-catch; must be inoculated within 1 hour of collection. Put into a blood agar. Inhibit growth of gram-positive so gram neg grows. Incubate at 35-37 degrees. Colony color, and hemolysis should be noted. Count of 100 000/mL or greater is evidence of UTI
37
What are some common gram positive bacteria
Staphylococcus and Streptococcus
38
Staphylococcus
Large, white or yellow ○ On Gram stain, appear spherical and in grape-like clusters
39
Streptococci
Small, colorless ○ Spherical, chains or pairs
40
Catalase test
used to perform on gram positive. staph is positive and strep negative
41
Coagulase test
can differentiate between Staph aureus and other staph
42
Identification of Gram-negative Bacteria
Klebsiella form bubblegum pink, mucoid colonies. Gram negative bacteria will grow on EMB and MAC. Reported as gram-negative rods, coliform by EMB, where coliform refers to intestinal bacteria
43
Antibiotic Susceptibility Tests
Tests which antibody works against certain viruses
44
Minimum inhibitory concentration (MIC)
Instruments perform bacterial identification. Swab bacteria on an agar plate and put antibodies in each section of an agar plate. The antibody that works the best when it has a circle around the antibody
45
vaginitis,
an infection of vagina
46
Common microorganisms in vaginitis
Gardnerella vaginalis, Mobiluncus species, Streptococcus group B, Chlamydia trachomatis, Neisseria gonorrhoeae, the protozoan Trichomonas and the yeast Candida albicans
47
waht is Saline wet mount prep
Mix drop of vaginal specimen with drop of 0.85% saline on slide
48
KOH prep of vaginal secretions for yeasts and fungi
2 drops vaginal material with 1 drop 10% KOH solution ■ Fungal elements appear as hairs or threads
49
Gram stain of endocervical secretions of bacteria and yeasts
G Vaginalis is gram-variable; scattered over constituents of smear ■ Yeast stains dark purple ■ Examined for N gonorrhoeae, which causes gonorrhea; gram-negative, kidney bean-shaped
50
urethritis
an inflammation of urethra
51
If midstream urine contains RBCs, bacteria, WBCS, or protein,?
then patient may have UTI instead of STD
52
how to do Urethral culture
Urethral discharge collected using urogenital swab and cultured for gonorrhea ○ Inoculated on MTM plate to identify gonorrhea
53
what does a Urethral gram stain do
Examined for WBCs and bacteria
54
Identification of Gonorrhea
N. gonorrhoeae appear as tiny, shiny, grayish colonies growing along steak pattern. Oxidase test can be used to aid in identifying colonies, which is positive. Purple-black color forms when oxidase-positive colonies are exposed to reagent
55
Types of herpes
Herpes simplex virus, type 1 (HSV-1) is responsible for cases of oral herpes and herpes simplex virus, type 2 (HSV-2) causes genital herpes
56
Identification of Herpes (HSV)
If herpes lesion present, vesicle can be broken with swab or needle and fluid collected with swab, which is then sent to lab for culture ● Serum titers of IgG and IgM can also be measured
57
Identification of Chlamydia
Caused by C. trachomatis ● DNA probes use specific nucleic acids, called probe DNA, that is added to patient specimen; if patient is positive, color/luminescence is produced ● In females, Chlamydia can cause cervix to bleed easily, cervix said to be friable
58
Identification of Syphilis
Syphilis is venereal disease caused by Treponema pallidum, a spirochete, or spiral bacteria ● Primary syphilis characterized by skin lesions, organ/tissue damage in secondary stage, cardiovascular/CNS affected in late-stage ● Patient with T. pallidum produces non-specific antibodies called reagin; RPR (rapid plasma reagin) test has carbon-containing cardiolipin antigen that reacts with reagin; also flocculation test
59
How do pandemics re-emerge and spread?
Environmental Change Population concentrations international FLights Public health Pathogen adaptation Natural disasters
60
West Nile Virus
In 2002, it caused largest WNV epidemic and animal epizootic ever reported, with 4000 human cases and 284 deaths in the US ● Normally transmitted by mosquitoes
61
West Nile Virus Symptoms
fever, hemorrhaging caused by organ damage
62
waht are Viral Hemorrhagic Fevers
Symptoms: fever, hemorrhaging caused by organ damage ● Caused by RNA viruses in 4 families: arenaviruses, filoviruses, bunyaviruses, flaviviruses
63
What are examples of Viral Hemorrhagic Fevers
Rift Valley Fever Ebola and Marburg viruses Severe Acute Respiratory Syndrome Avian influenza
64
Rift Valley Fever
Rift Valley fever occurs in livestock and humans in Africa ○ Caused by virus of Bunyaviridae family and transmitted by mosquitoes
65
Ebola and Marburg viruses
Ebola and Marburg viruses are filoviruses that cause high mortality ○ WHO documented 17 outbreaks in humans
66
Severe Acute Respiratory Syndrome
Mycobacterium tuberculosis causes tuberculosis ○ As HIV has increased worldwide, incidence of TB has also increased
67
Avian influenza
Reservoir for influenza A are birds ○ Outbreak in May 2006 in Indonesia was possible pandemic
68
What are biological weapons?
Diseases used againest peopl in war
69

Clinical Laboratory Science (8 decks)

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