Unit 1 Flashcards
To survive, microbial inhabitants have learned to adapt by varying all of the following, except
Bacterial shape
Who has considered the father of protozoology and bacteriology?
Anton van Leeuwenhoek
Prokaryotic cells have which of the following structures in their cytoplasm?
Ribosomes
The form of DNA is commonly found in eukaryotic cells
Linear
The nuclear membrane in prokaryotes is
Missing
A microorganism that is a unicellular organism and lacks a nuclear membrane and true nucleus belongs to which classification?
Bactria
In the laboratory, the clinical microbiologist is responsible for all the following, except
Selecting treatment for patients
What enables the microbiologist to select the correct media for primary culture and optimize the chance of isolating a pathogenic organism?
Understanding the growth requirements of potential pathogens at specific body site
A clinical laboratory scientist is working on the bench, reading plates, and notices that a culture has both a unicellular form and a filamentous form. What type of organism exhibits these forms?
Fungi
All of the following statements are true viruses, except
Viruses do not need host cells to survive and grow
Diagnostic microbiologists apply placement and naming bacterial organisms into all the following categories, except
Order
Bacterial species that exhibit phenotypic differences are considered
Subspecies
What structure is described as a phospholipid bilayer embedded with proteins and sterols that regulates the type and amount of chemicals that pass in and out of a cell?
Plasma membrane
What makes the interior of the plasma membrane potentially impermeable to water-soluble molecules?
The hydrophobic tails of the phospholipids molecules are found there
The function of a cell wall is to
Provide rigidity and strength to the exterior of the cell
Name the numerous short (3-10 um) projections that extend from the cell surface and are used for cellular locomotion
Cilia
A microbiology technologist performs a traditional bacterial stain on a colony from a wound culture that is suspected to contain bacteria from the genus clostridium. The unstained areas in the bacterial cell observed by the technologist are called
Endospores
This constituent of gram-positive cell walls absorbs crystal violet but is to dissolved by alcohol, thus giving the gram-positive cell its characteristic purple color
Peptidoglycan
Mycobacteria have a gram-positive cell wall structure with a waxy layer containing these two compounds
Glycolipids and mycolic acid
When performing a Gram stain on a gram-negative organism, the crystal violet is absorbed into this outer cell wall layer, and then washed away with the acetone alcohol. What is the main component of the outer layer of the cell wall?
Lipopolyaccharide
The three region of the lipopolysaccharide include all of the following except,
Myocolic acid
The outer cell wall of the gram-negative bacteria serves three important functions, which includes all the following except
It provides an attachment site for flagella, which will act in locomotion
Mycoplasma and Ureaplasma spp. must have media supplemented with serum or sugar as nutrients and because
The lack cell walls
Whaat is the purpose of a capsule?
Act as a virulence factor in helping the pathogen evade phagocytosis
The three basic shapes of bacteria include all the following except
Cell wall deficient
The gram stain is a routine stain used in bacteriology to determine gram-positive and gran-negative based on the
Composition of the bacterial cell wall
In what staining procedures does carbofuchsin penetrate the bacterial cell wall through heat or detergent treatment?
Acid-fast stain
What stain is used for medically important fungi?
Lactophenol cotton blue
All of the following are types of media, excerpt
Fastidious
Which of the following environmental factors influence the growth of bacteria in the laboratory?
All of the above
* pH
* temperature
* Gaseous composition of the atmosphere
Some bacteria grow at 25-42 C, but diagnostic laboratories routinely grow pathogenic bacteria at what temperature?
35C
Which of these bacteria cannot grow in the presence of oxygen?
Obligate anaerobe
What class of organisms, such as the Streptococcus sp., can survive in the presence of oxygen but do not use oxygen in its metabolic processes?
Aerotolerant anaerobe
The laboratory receives a specimen in which the doctor suspects that the infecting organism is carbon dioxide. It is therefore classified as what type of bacteria?
Capnophilic
The following describes the log phase of bacterial growth
Bacteria doubling with each generation time
Diagnostic schemes is the microbiology laboratory typically analyze each unknown bacterium’s metabolic processes for all the following, except
Energy utilization for metabolic processes
Which is a biochemical process carries out by both obligate and facultative anaerobes?
Fermentation
What type of fermentation produces lactic, acetic, succinic, and formic acids as the end products?
Mixed acid
If bacteria utilize various carbohydrates for growth, they are usually detected by
Acid production and change of color from the pH indicator
In the medical microbiology laboratory, the ability of gram-negative bacterium to ferment this sugar is the first step in its ID
Lactose
A ________ is a single, closed, circular piece of DNA that is supercoilded to fit inside a bacterial cell
Chromosome
Genes that code for antibiotic resistance are often found on small, circular pieces of DNA. The DNA pieces are called
Plasmids
What process involves transferring or exchanging genes between similar regions on two separate DNA molecules?
Recombination
A microbiologist is working with two separate cultures of the same organism. The bacteria in one culture are resistant to penicillin, whereas the bacteria in the other culture are susceptible to penicillin. The bacteria from both cultures are mixed together, and all the resulting bacteria are resistant to penicillin. What caused this phenomenon?
The plasmid carrying the resistance gene was transferred to the susceptible population of bacteria
Diphtheria is a disease produced by corynebacterium diphtheria. However, not all C. Diphtheriae bacteria produce the toxin that causes this disease. To produce the toxin, the bacteria must first become infected with a bacteriophage. The process by which bacterial genes are transferred to new bacteria by the bacteriophage is called
Transduction
Lysogeny occur when
Genes present in the bacteriophage DNA are incorporated into the bacteria’s genome
These are enzymes that cut the bacterial DNA at specific locations
Restriction enzymes
Organisms that participate in a biological relationship where both benefit from one another are called
Symbionts
Parasitism is
A biological relationship in which one species gains benefits at the expense of the host
This bacterial state occurs when a host harbors a disease-causing organism, but does not show signs of disease
Carrier
Healthy people are colonized by many different sites. These bacteria are referred to as
Indigenous flora
Diabetics may sometimes be infected with their own resident flora. This type of infection is called
An opportunistic infection
Mechanism used b the skin to prevent infection and protect the underlying tissue from invasion by potential pathogens include all the following, except
Antibiotics that inhibit many microorganisms
A laboratory professional is testing a new antimicrobial soap. The tech washes her forearm then does a culture of the skin. Which organisms should she most likely expect to find growing in the culture?
Staphylococcus epidermis and propionbacterium
What mechanism allows strict anaerobes to grow in the cervices and areas between the teeth when plaque is present?
A low oxidation-reduction potential occurs at the tooth surface under the plaque
The stomach can be considered a first line of defense against microbial infections because
Most microorganisms are susceptible to to the acid pH of the stomach
This type of bacteria is able to live in the colon with little to no oxygen and is the predominant organisms
Anaerobes
After perforation of the colon, surgeons must guard against infection in the _________ because of leakage of the contents of the colon
Peritoneal cavity
The human body is constantly challenged by pathogens in the environment. It is not infected by every pathogen it encounters because the microbial flora
Produce conditions at the microenvironmental level that block colonization
The ability of an organism to produce disease in an individual is called
Pathogenicity
A patient with a n indwelling catheter develops a fever and lethargy. In addition, the urine in the catheter bag has turned a brownish color and smells foul, which suggests an infection is present. What type of infection does this describe?
Iatrogenic
The smaller the number of microorganism necessary to cause infection in competent Host, the more _______ ad the microorganism
Virulent
Factors the determine the pathogenicity and increase the virulence of organism include all the following, except
An organisms ability to produce infection when host conditions change
The most common bacterial characteristic that allows for evasion of phagocytosis by the host is called
Polysaccharide capsule
This is a leukocidin that is lethal to leukocytes and produces by staphylococci
Panton-valentine
Changes in these host structures can result in lower virulence of microorganism
Adhesion receptors
After attachment to host cells, a pathogen may use the following mechanisms to establish itself and cause disease, except
Produces lysozyme to kill the host cell
Dissemination of a pathogen is
When infection with a pathogen spreads from the initial infection site to distant site such as organs and tissues
A physician notices that several patients are infected with clostridium difficile, but only a few of the patients are symptomatic for disease. The reason for this discrepancy is
Only those strains of the organsisms carrying the extrachromosomal DNA coding for the toxin gene will produce ten and cause the individuals to be symptomatic
The effects of endotoxins consist of dramatic changes in all the following, except
Fluid imbalance
A patient is brought to the emergency room with the following symptom: body temperature of 102 F, low blood pressure, elevated WBC, and disseminated intravascular coagulation. This person has gram-negative rods growing in the blood. What is responsible for these symptoms?
Endotoxin
Healthy skin secretes these substances to help prevent colonization by transient and possibly pathogenic organisms
Long-chain fatty acids
Lysozyme is
A low-molecular-weight enzyme that hydrolyzes the Peptidoglycan layer of bacterial wall
Interferon is a substance produced by the body that inhibits viral replication. Interferon accomplishes this task by
Binding to surface receptors that stimulate the cell to synthesize enzymes that inhibit viral replication over several days
All of the following activities must occur for phagocytosis to take place and be effective in host defense, except
Migration of lymphocytes to the area of infection (chemotaxis)
This process results in enhanced phagocytosis by neutrophils
Opsonization
One of the most effective defenses bacteria have against phagocytosis is
The capsule
Innate immunity consists of which of the following components?
All of the above are part of the innate immune system
The major constituents of the adapative of specific immune response are
Lymphocytes
The class of antibodies is usually found as a pentameter
IgM
A subsequent exposure to the same antigen elicits a(n) ________, characterized by a rapid increase in IgG antibody associated with higher levels, a prolonged elevation, and a more gradual decline in antibody levels
Anmnestic immune response
These are low-molecular-weight proteins secreted by T cells
Lymphokines
Immunity to intracellular bacterial pathogens, such as mycotoxins bacterium tuberculosis, is primarily cell mediated, through the activities of
T lymphocytes, lymphokines, and a macrophages
Pathogens can be transmitted through all the following routes, except
Handwashing
Because infections can be encountered via the air, _______can cause transmission of some pathogens
Coughing
The resulting disease from this route of transmission is a disease of animals that is transmitted to humans
Zoonotic
The chemical or physical method that destroy all forms of life is called
Sterilization
Organisms that are the most resistant to heat, chemicals, and radiation are
Prions
After using the phone, the laboratory tech sprayed the receiver with a chemical spray. This process will kill a defined scope of microorganisms. What is this process called?
Disinfection
before performing a phlebotomy, the phlebotomist will clean the area on a patients arm with a substance before inserting needle. This substance is called an
Antiseptic
All of the following factors play a significant role in the selection and implementation of the appropriate method of disinfection, except
Humidity
When eliminating organisms from inanimate objects, higher numbers of organisms require longer exposure time because
It takes longer to eliminate 99% of microorganisms
If this is present on a surface to be disinfected, it can shield microorganisms from the disinfectant or inactivate the disinfectant. What is this substance?
Organic material
Disinfectants are usually used at this temperature
20-22 C
Pasteurization achieves______?
Disinfection
Chemosterilizers exert their killing effect through all the following mechanisms, except
Inactivating enzyme substrates
Alcohol use this mechanism to inactivate microorganisms
Denature proteins
The tech needs to sterilize a piece of equipment that cannot be autoclaved or gas sterilized because the equipment contains lenses, metal, and rubber components. What solution should be used to sterilize this piece of equipment?
Glutaraldehyde
For the most effective microbial killing, all iodophors must be properly diluted because
There must be enough free iodine to kill the microorganisms
Even though hypochlorites are inexpensive and have broad range of microbes that they kill, they are not used as sterilants because of
Long exposure time for sporicidal action
Many materials in hospitals that must be sterilized cannot withstand steam sterilization. Gas sterilization is used instead, using this gas
Ethylene oxide
Why should health care workers wash their hands after coming into contact with a patient?
To reduce the spread of pathogenic bacteria from one individual to another
High-level disinfectants are active against all the following, except
Parasites
This agency regulates the use, sale, and distribution of antimicrobial pesticide products from certian inanimate, hard, nonporous surfaces, or incorporates into substances under the pesticide law
Antimicrobial division of environmental protection agency (EPA)