Unit 4 Exam Review Flashcards
Bacteremia that occurs when chewing food or brushing teeth
Transient
Bacteremia that is released into the bloodstream at a fairly consistent rate. Ex. Septic shock, endocarditis, early stages of typhoid fever, brucellosis, leptospirosis
Continuous
Bacteremia that infections demonstrate bacteria at variable times. This occurs in patients with un-drained abscesses. Bacteria may be released about 45 minutes before a febrile episode
Intermittent
Bloodstream infection that originates within the cardiovascular system
Intravascular
Bloodstream infection that enters the circulation through the lymphatics from another site of infection. Common portals of entry include the Genitourinary tract, respiratory tract, abscesses, surgical wound infections, and the biliary tract
Extravascular
Bacteria in the blood or the toxins produced by the bacteria causes harm to the host. Bacteria multiply more rapidly than immune system can work
Septicemia
Basic symptoms of septicemia
Fever or hypothermia, chills, hyperventilation, skin lesions, change in mental status, diarrhea
Serious symptoms of septicemia
shock or hypotension, disseminated intravascular coagulation (DIC), major organ failure, septic shock
What is used to clean the area for blood culture?
70% alcohol and another antiseptic (iodine)
How long should antiseptic stay on the skin when collecting a blood culture?
Follow manufacturer’s suggestions for recommended length of time
What type of broth is used in blood cultures?
Enrichment broth
How much bacterium is a blood culture designed to enhance?
Designed to enhance the growth of even one bacterium
What type of blood culture system do most labs use?
A dual system with an aerobic and anaerobic bottle.
What is the amount of blood needed for an adult blood culture? What is the minimum?
10-20 mL with a 10mL minimum
Why is so much blood needed for an adult blood culture?
Typically fewer bacteria per mL in adults in children
What is the amount of blood needed for a child’s blood culture?
1-5mL
Why is so little blood needed for a child’s blood culture?
More bacteria per mL may be adequate. Not safe to take large volumes of blood from children.
How many bottles are needed for a blood culture sample?
2 or 3 sets are sufficient. More may be necessary if patient is on antibiotics
How often are blood culture samples supposed to be collected?
spaced 1 to 2 hours apart.
Which is more important. The number of cultures or time interval they are collected?
Number of cultures
Which type of blood culture sample is more important to collect? The aerobic or anaerobic?
Aerobic. Recovery of anaerobic bacteria in blood is much more infrequent than recovery of aerobic bacteria
What needs to be done to blood culture bottles?
Provide proper incubation temp, constant agitation and continuous monitoring
What do blood culture bottles contain?
Nutrient broth, resins or charcoal and SPS
What system measures the production of CO2 produced by the metabolizing organisms by using fluorescence.
BACTEC
How do you know if bacteria is growing in a blood culture bottle?
Sensors on the bottom of each bottle increase in fluorescence as bacteria grows
What system measures CO2 and pH changes by a colormetric sensor located on the bottom of each bottle?
BacT/ALERT
How does a BacT/ALERT sensor work?
Sensor is separated from the broth by a membrane which is permeable to CO2. As the organism produces CO2, the sensor changes color
What do WBC give off in a blood culture?
CO2
What must be done to a positive blood culture?
A sample of the culture broth must be gram stained. A sample should also be plated onto conventional media which supports aerobic and anaerobic growth
Contaminate or Pathogen?
Growth of Bacillus, multiple organisms from several cultures, clinical presentation inconsistent with sepsis, infection at primary site of infection
Contaminant
Contaminant or Pathogen?
Growth of the same organism in repeat cultures, growth of certain organisms from endocarditis, growth of organisms such as enterbacteriaceae, growth of commensal organisms from immune-compromised patients
Pathogen
Possible pathogens with special requirements
HACEK Fungi Mycobacteria Brucella Mycoplasma Campylobacter
Inflammation of the tracheobronchial tree
Acute Bronchitis
Symptoms of acute bronchitis
cough, variable fever, and sputum production
What causes acute bronchitis
Viral agents and may be part of or proceeded by an URI (flu or common cold)
What can be a complication of acute bronchitis in infants and preschool aged children?
Bordetella pertussis should be considered
Excessive mucus production which leads to coughing up sputum on most days at least 3 months to two years.
Chronic bronchitis
What causes chronic bronchitis?
Bacteria may be the cause of acute flare-ups, but viruses are the more frequent cause
Inflammation of the lower respiratory tract involving the lung’s airways and supporting structures
Pneumonia
Associated pathogens are age-dependent
Ex. S. pneumonia, H. influenza, M. catarrhalis, M. pneumonia, C. pneumonia, Legionella
Community acquired bronchitis
Pathogens will include MRSA, P. aeruginosa, K. pneumonia, E. coli
Health care associated pneumonias (HCAP)
Infection caused by an organism infecting the lung and then gaining access to the pleural space via an abnormal passage
Pleural infections
Primary type of sample. Will be contaminated with upper respiratory secretions. Specimen should be the result of a deep cough
Expectorated Sputum
A respiratory therapist may need to assist patients and use postural drainage or thoracic percussion to stimulate production.
Induced Sputum
What type of reagent is used to induce sputum?
Aerosol induction. Breathe a 15% sodium chloride - 10% glycerin mix for 10 minutes
Invasive procedure which allows the physician to obtain bronchial washings or broncheoalveolar lavage samples; may also do bronchial brushings
Bronchoscopy
What might be performed if there is pleural fluid present in a Bronchoscopy?
Thoracentisis
Secondary Endotrachael and Transtracheal aspirates
What is the most common direct exam?
Gram stain
What is easy to recognize in a gram stain?
Bacteria and yeast
What are the requirements of a good sputum smear?
Fewer than 10 squamous epithelial cells per low power field.
What implies and excellent sputum specimen?
The presence of 25 or more WBC and a few epithelial cells
Presence of WBC is not necessary for acceptance of a specimen.
What can be examined for the presence of parasites and fungi
Wet prep
What can be used to identify acid-fast bacilli
Acid-fast stains
What may be used to detect Legionella?
Direct fluorescent antibody
What plates are used for differentiation of gram negative bacilli
Sheep blood and MacConkey
What plate is used for differentiation of Haemophilus and Neisseria?
Chocolate
What agar should be used if legionnaires disease is suspected?
BYCE Buffered charcoal yeast extract
What type of media is not used in specimens thought to contain contaminating oral flora
Enrichment media
What type of bacteria may require special procedures for detection?
Mycobacteria, Chlamydia, Nocardia, B. pertussis, Legionella, and Mycoplasma pneumonia
What type of URT Infection is usually caused by viruses?
Laryngitis
What type of URT Infection is caused by a virus which usually occurs in children under 3
Croup (Laryngotracheobronchitis)
Usually caused by H. influenza type b; Most common in children between 2 and 6; can be very dangerous because airway may be blocked
Epiglottitis
May accompany several viral infections. most bacterial infections are cause by S. pyogenes;
Pharyngitis
Usually caused by viruses; C. diphtheria may be isolated from patients with sore throat; massive immunization has reduced infection with Bordetella pertussis, but outbreaks still occur
Rhinitis
Inflammation of the mucous membranes of the oral cavity - caused by HSV
Stomatitis
Caused by Candida spp. usually occurs in young infants or immunocompromised patients
Thrush
What type of swabs are suitable for collecting most upper respiratory microorganisms
Cotton, Dacron or calcium alginated tipped swabs
What are transport requirements of swabs?
Remains moist - cultured within 4 hours.
Longer use a transport media
What types of swabs are better for recovering viruses, Neisseria and B. pertussis
Nasopharyngeal swabs
What organism are most throat cultures screened for?
S. pyogenes (group A)
What media is used to screen most throat cultures?
5% sheep blood agar
What may be placed on the inoculation of bacteria for presumptive ID
0.04 unit differential bacitracin disk
What plates should be plated if Corynebacterium is suspected?
Sheep blood, streptococcal selective, Loeffler’s and cysteine-tellurite agar plate
What types of plate is cultured for Bordetella pertussis?
Bordet-Gengou agar in past.
Today the more common choice is Regan-Lowe or charcoal horse blood agar
What types of plate is cultured for Neisseria?
Thayer-Martin or Martin-Lewis agar
What plates should be cultured from epiglottitis?
Sheep blood and chocolate
How many products are there to test for Rapid Group A strep?
40
What type of technologies are used for rapid strep test?
Latex agglutination, enzyme immunoassay, gene probe technology
How long does a rapid strep test take?
10 minutes or less
What are other methods are used for direct detection of influenza viruses
EIA, PCR, DFA
How long do different methods for rapid viral testing take to process?
EIA - 10-30 minutes
PCR - 2 hours
DFA - 2 hours
What are UTI’s associated with?
Sexual intercourse, hormonal changes, diabetes, renal disease, renal transplantation, structural and neurologic abnormalities that interfere with urine flow
How are UTI’s associated with hospitalization?
catheterization
What is the most common source of UTI?
E. coli other than catheterization
What are other agents of infection for UTI?
Klebsiella, other Enterbacteriaceae, and S. Saprophyticus
In recurrent infections what organisms are more common?
Proteus, Pseudomonas, Klebsiella and Enterobacter spp.
Infection of the urethra is common. C. trachomatis, N. gonorrhoeae and T. vaginalis are common causes and are discussed further under genital infections
Urethiritis
Infection of the bladder. Symptoms include dysuria, frequency and urgency. Often there is pain over the area over the area of the bladder
Cystitis
Symptoms are similar to systitis but there are fewer bacteria (less than 10^5 CFU/mL). It may be caused by STDs but is often caused by the same bacteria which cause cystitis
Acute urethral syndrome
Inflammation of the kidney parenchyma, calices and pelvis
Pyelonephritis
What UTI infection may be significant in pregnancy
Asymptomatic Bacteriuria
UTI sample collection: Involves cleansing prior to urination. Sample collection does not begin until the urine starts to flow and collection should end before the flow stops
Clean catch (midstream)
UTI sample collection: A catheter is inserted into the urethra. Contamination may occur from introducing organisms from the urethra
Straight catheterization
UTI sample collection: Urine is withdrawn directly from the bladder into a syringe through a percutaneously inserted needle
Suprapubic bladder aspiration
UTI sample collection: Patients with “permanent” catheters often develop bacteriuria. Urine may be aspirated from catheter tubing using aseptic technique
Indwelling catheter
What should be done with urine samples?
Transported to the lab as soon as possible, refrigerated, or preserved
What tests are done before a urine culture?
Urinalysis, leukocyte esterase, nitrate, possible gram stain
What is the threshold for a low colony count so screening tests are not necessary?
10^2-10^3
What are the two sizes of calibrate loops that are used?
0.01 or 0.001 mL
What is the colony count for a 0.001 loop?
1000 CFU/mL
What plates are inoculated and what are the culture requirements for urine specimens?
5% sheep blood and MacConkey @35C for 24 hrs.
Describe the special technique for streaking a plate for a urine culture.
A line is made with the calibrated, inoculated loop pulling downward. The loop is then drawn across the line in a zigzag manner. The loop is not flamed during this step.
How do urine colony counts help a laboratorian?
They can determine if the growth is a contaminant or pathogen.
What are the collection requirements for sterile body fluids?
Collect by aspiration with syringe, transport in sterile container, no refrigeration, concentrate by centrifugation, decant supernatant and process specimen for culture and direct gram stain
1 organism/oil field is equal to _____?
10^5 org/mL
What plates should be inoculated for sterile fluids? How long to incubate? What has special requests?
BA, Choc, Mac, broth incubate 3-7 days
Special requirements for AFB, Mycology, Anaerobes, rapid test
What is normally found in GI tract infections?
A variety of flora
What percentage of feces is bacteria? What kind?
80%, mostly anaerobes
How fresh should a stool specimen be?
Received within 30 minutes in a clean container
A delay in transport of a fecal specimen requires what transport media?
Cary-Blair for bacterial culture
What type of selective agars should fecal specimens be plated on?
XLD
CCDA
Selenite broth
Molecular and antigen detection methods are also used
What type of organisms normally colonize the Genital tract?
Commensal
How are infections that may be caused by the patient’s endogenous flora transmitted?
Sexually
What type of specimens are used for Genital tract infections?
Urethral, cervical/vaginal
Who must monitor and control incidence of hospital acquired infections?
Infection Control
What areas have the highest rates of hospital acquired infections?
Surgical and medical services
What are the three factors for infection control?
Susceptibility, virulence, exposure
What is the purpose of Infection Control?
Detect and monitor nosocomial infections and prevent their spread; investigate the source of an outbreak
What includes the attending physician, IC nurse, microbiologist, epidemiologist and pharmacist?
The IC Committee
Name 3 disadvantages to hospital acquired infections?
Adds to healthcare costs, contributes to mortality and morbidity, puts healthcare workers at risk
What is the most effective infection control procedure?
Handwashing or sanitizing
The majority of nosocomial infections involves the patient’s own _____?
Endogenous flora
What can surpress an immune system?
Steroids, chemo, and antimicrobials
Natural barriers of infection control are broken by _____?
Urinary and IV catheters
Name 5 predisposing factors?
age, therapies, skin integrity, surgical procedures, nutrition and obesity
What is the most common cause of nosocomial UTIs?
gram neg rods
What is the most common cause of nosocomial respiratory infections?
Pneumonias from gram neg rods, S. aureus, H. influenza
What is the most common cause of nosocomial surgical infections?
Gram pos rods, gram neg rods and yeast (50% occur after discharge)
What is the most common cause of nosocomial bloodstream infections?
CNS, Enterococcus, S. aureus, yeast and gram neg rods
What is the most common cause of nosocomial GI infections?
C. difficile
Modes of spread:
Direct contact
food, IV
Modes of spread:
Indirect contact
patient to patient
ex. MRSA
Modes of spread:
Droplet
B. pertussis, N. menin, Mumps
Modes of spread:
Airborne
TB measles
Modes of spread:
Vectors
mosquitoes, mites
What are 1970s CDC guidelines for infection control prevention?
Hand washing, segregation of infected patients, appropriate PPE, bagging contaminated items, cleaning rooms between patients, door signage
What two infections have a BOLO?
CRE and VRSA
This network include labs at CDC, USDA, FDA and other facilities run by federal agencies
Federal
This network include labs run by state and local departments of health. In addition to being able to test for Category A biological agents, a few LRN public health labs are able to measure human exposure to toxic chemicals through tests on clinical specimens
State and local public health
This network includes labs operated by the Department of Defense located both within the United States and abroad
Military
The LRN includes FDA and USDA labs, and others that are responsible for ensuring the safety of the food supply.
Food testing
Includes labs that are capable of testing water and other environmental samples
Environmental
Some LRN labs, such as those run by USDA, are responsible for animal testing. Some diseases can be shared by humans and animals, and animals often provide the first sign of disease outbreak
Veterinary
The LRN has labs located in Canada, the United Kingdom, Australia, Mexico and South Korea
International
This lab has the unique resources to handle highly infectious agents and the ability to identify specific agent strains
National labs
This lab can perform tests to detect and confirm the presence of a threat. These labs ensure a timely local response in the event of a threat incident. Rather than having to rely on confirmation from labs at CDC, these labs are capable of producing conclusive results. This allows local authorities to respond quickly to emergencies
Reference labs
These labs represent the thousands of hospital-based labs that are on the front lines. These labs have direct contact with patients. These labs could be the first facility to spot a suspicious specimen. This labs responsibility is to refer a suspicious sample to the right lab.
Sentinel labs
These labs work with hospitals and other first responders within their jurisdiction to maintain competency in clinical specimen collection, storage, and shipment
Level 3 Labs
Chemists in these labs are trained to detect exposure to a number of toxic chemical agents. Analysis of cyanide, nerve agents, and toxic metals in human samples are examples of this labs activities
Level 2 Labs
These labs, which serve as surge-capacity labs for CDC, are able to detect toxic chemical agents and exposure to an expanded number of chemicals, including mustard agents, nerve agents, and other toxic industrial chemicals. Using unique high-throughput analysis capabilities, they expand CDC’s ability to analyze large number of patient samples when responding to large-scale exposure incidents
Level 1 Labs
What is a VITEK instrument?
Automated system for ID and antimicrobial susceptibilities of bacteria and yeast
While providing more safety what does a VITEK instrument eliminate?
Repetitive manual operations
What are some features for a VITEK instrument?
Bi-directional interface
Epidemiology report module
Expert software for on-line result validation
Several models available
How big is a VITEK Test Card?
The size of a playing card made up of 30 or 45 micro wells
How is the VITEK card transported?
sealed container, no aerosol or splattering, spills or personal contamination
What is DataTrac?
information management system that oversees the test data generated by the VITEK
How does DataTrac work?
Information gathers and formatted into reports and exported for analysis in other PC based programs
What type of interface does DataTrac have?
bidirectional
What type of system does the VITEK2 have?
unique, closed system with 64 well test cards
AST
Antimicrobic Susceptibility Testing
What is AST aimed at?
High Quality MIC with extended ranges
What does the AST workflow provide?
Improve processes with Security & Productivity
What does the AST Therapy provide?
Fast results on High-efficacy, low cost therapy
What does the AST Economics provide?
Lab investment leading to hospital savings
What does the AST Outcome provide?
Rapid information for Efficiency and Cost Containment
What is the purpose of BacT/ALERT?
Instrument designed to process numerous blood cultures automatically. Cultures are incubated, positives are detected and technologist is alerted
What are some advantages of BacT/ALERT?
saves time, facilitates cross training and helps prevent errors
What is the technology used for BacT/ALERT?
Colorimetric
How does BacT/ALERT work?
sensor and detection method finds microorganisms by tracking CO2 production
What color does the sensor turn when microorganisms multiply in the media, generating CO2
yellow
The BacT/ALERT monitors and detects color changes in the sensor after measuring _____?
reflected light
What analyzes the data to determine positivity and identifies the lab with visual and audible alarms?
Algorithms
What are benefits of alternate methods in microbiology?
rapid, larger volume, higher sensitivity and specificity, more cost effective
Technique in which single stranded NA is allowed to interact so that complexes called hybrids are formed by molecules with similar, complementary sequences
Nucleic acid hybridization
What are the 4 steps of nucleic acid hybridization
- production of probe
- prep of target
- mix target and probe
- detect hybridization
What are advantages of nucleic acid hybridization?
detects both non-viable organisms and ones that can’t be readily be grown in culture, detects slower growing organisms, can quantitate infectious agents, may ID organism already growing in culture
What do serologic methods detect?
rise in titer of a specific antibody in the patient
What are different types of serologic procedures?
IFA, FTA-ABS, Western Blot, ELISA, Hemagglutination
