microbiology Flashcards
Classes of Biosafety Cabinet
-Allow room air to pass into cabinet and around the area and material within, sterilizing only the air to be exhausted
-consist of negative pressure
-operated in open front
Class I
Classes of Biosafety Cabinet
-air flows in “sheets”, which serves as a barrier to particle from outside the cabinet
Direct the flow of contaminated air into the filters
-also called as VERTICAL LAMINAR FLOW BSCs
Class II
Classes of Biosafety Cabinet
-self-contained, and 70% of the air is recirculated.
Class IIA
Classes of Biosafety Cabinet
-selected for radioisotopes, toxic chemicals or carcinogenic samples
Class IIB
-very simple microbes, consisting of nucleic acid, a few proteins, and (in some) a lipid envelope.
-completely dependent on the cells they infect for their survival and replication.
virus
-with both RNA and DNA, metabolic machinery for self-replication, and a complex cell wall structure.
Prokaryotic - simple unicellular organisms
bacteria, prokaryotik
-subdivided into single-celled organisms (yeasts) or multi-celled organisms
(molds), with a few medically important members existing in both forms (dimorphic fungi).
fungi
-subdivided into single-celled organisms(protozoa) or multi-celled organisms (worms and bugs).
parasites
• Prokaryotic unicellular organisms that lack a true nucleus and nuclear membrane
• Single, closed, circular chromosomes of double-stranded DNA called
NUCLEOID.
• PLASMIDS: small circular molecules of extrachromosomal circular DNA
• May either be GRAM POSITIVE or GRAM NEGATIVE
BACTERIA
asexual reproduction of bacteria
BINARY FISSION:
size: range from 0.2 to 2um in diameter and 1 to 6um in length
Gram Stain
• Principal stain used for microscopic examination of bacteria
• First devised by Hans Christian Gram during the late 19th century
• Divide most bacterial species into two large groups:
• Gram-positive: take up the basic dye, crystal violet
• Gram-negative: allow crystal violet dye to wash out easily with decolorizer alcohol or acetone
BACTERIA
spherical-shaped cells
COCCI:
rod-shaped cells
BACILLI
spiral shaped cells
SPIRILLA
comma- shaped cells
VIBRIOS
-Process by which bacteria catabolize carbohydrates to produce energy
FERMENTATION
-also known as oxidation
-Process of bacterial energy generation rather than fermentation
RESPIRATION
• Universal Precautions are followed throughout the collection and handling process.
• Persons collecting or handling specimens should wear gloves and a laboratory gown
• Eye protection should also be worn if splashing
• Accidents or injuries (needle prick) must be reported immediately.
Safety
• Specimen should be from the infection site and not contaminated by the surrounding area
• Specimen should be collected before antimicrobials are administered
(Antibiotics)
• Appropriate collection devices and containers should be used and must be
STERILE! ASEPTIC TECHNIQUE is required.
• Specimen container should LABELED with patient’s identification, the date and time of collection and the source of specimen
General Guidelines
• Tongue should be depressed before swabbing between the tonsillar pillars and behind the uvula.
• The cheek, tongue, and teeth should NOT be touched.
Throat (Swabs)
• Expectorated specimens from deep cough should be collected into a sterile specimen cup
• NOTE: Early morning specimens are the best.
Sputum
• Should never be taken from the toilet and should not be contaminated with urine
Stool
• Midstream clean-catch is the most common collection method.
• Culture for catheterized urine specimens usually have less contaminating bacterial flora
Urine
• 2 to 3 cultures should be collected at random times during 24-hour period.
• Skin is disinfected with 70% alcohol, followed by lodine
Blood
Blood
20-30mL of blood per culture is collected
ADULT
Blood
1-5mL of blood per culture is collected
INFANTS
• Should be collected aseptically by
PHYSICIAN
• Should be processed immediately and not exposed to heat or refrigeration
Cerebrospinal fluid
Genital Tract
• Exudates may be expressed from the urethral orifice or a small-diameter swab inserted 3 to 4 cm into the urethra.
MEN (penile discharge)
• A sterile swab is inserted into the cervix with a aid of speculum
• Swab is rotated and allowed to remain for a fer seconds
WOMEN (vaginal discharge)
(t or f)
Anaerobic specimens must be transported in an anaerobic system.
2. Swab samples are not allowed to dry out
3. Most specimen can be held at 2°C to 8°C if transport cannot occur immediately
EXCEPT:
a.Temperature-sensitive organisms
b. Blood culture bottles
C.CSF (Cerebrospinal fluid)
true
• Support the growth of a wide range of microorganisms and are considered non-selective because, the growth of most organisms is supported
• Example: Blood Agar Plate and Chocolate Agar
NUTRITIVE MEDIA
• Microorganisms that can be distinguished on the basis of certain growth characteristics evident on the medium
• Example: Blood agar plate
DIFFERENTIAL MEDIA
• Support the growth of one group of organisms, but not another, by adding antimicrobials, dyes, or alcohol to a particular medium.
• Example: MacConkey Agar, Columbia agar with colistin and nalidixic acid (CNA)
SELECTIVE MEDIA
• Also called supplemental or enrichment broth
• For detection of small numbers of organisms present
Example: Thioglycollate (Thio) broth, brain-heart infusion broth (BHIB) and tryptic soy broth (TSB)
BACKUP BROTH
Used when specific organisms are suspected
• Example: Mannitol salt agar, bismuth sulfite agar, Campylobacter agar, Thiosulfate-citrate-bile salts-sucrose (TCBS) agar
SPECIALIZED MEDIA
INCUBATION
Normal incubation temperature for bacterial cultures
-Anaerobic jars, bags, or an anaerobic chamber are appropriate for incubation of anaerobic cultures
35°C-37°C
INCUBATION
for stool cultures for detection of Campylobacter jejuni
42°C to 45°C
(t or f)
- Specimen received in nonsterile or contaminated containers
- Specimen contaminated with barium or other foreign substances
- 24- hour urine or sputum collections
- Saliva instead of sputum
- Unrefrigerated urine specimens 2 hours or more post-collection
true
