What type of genetic test provides information about an asymptomatic person’s risk for having a child with a specific autosomal-recessive disorder in the future?
Which tissue is most likely to provide an adequate DNA sample for genetic testing?
A)Distal ends of hair shafts
B)Mature red blood cells
C)Nasal epithelial cells
D)A mummy’s tooth
Genetic testing that examines an asymptomatic person’s DNA sequence, looking for mutations that increase a person’s susceptibility to a disease, is an exampleof whichtype of testing?
How is cell-free DNA (cdDNA) testing being used clinically?
A)To determine a person’s risk for developing breast cancer
B)As an inexpensive alternative to standard paternity testing
C)As a less invasive way to determine the characteristics of cancer cells
D)As a way to determine whether a specific suspect has committed a rape
You explain general mechanisms of antibiotic resistance to your patient’s family. Which of the following mechanisms is not one used by S. aureus?
A) Some bacteria produce enzymes that chemically modify a specific medication, interfering with its function. An example is the β-lactamases that inactivate different β-lactam antibiotics.
B) Some bacteria use efflux pumps to transport antimicrobials and other damaging compounds out of the cell. Sometimes the pumps are structurally altered, conferring resistance to several different antimicrobials simultaneously.
C) Some bacteria are able to make minor structural changes in the cellular target of a drug. This can prevent the medication from binding to that target, thereby protecting the organism from its effects.
D) Some bacteria can make changes in porin proteins of the outer membrane and can therefore prevent certain antimicrobials from entering the cell’s cytoplasm. By stopping entry of an antimicrobial, an organism avoids its effects.
E) Resistance in S. aureus may involve any of these mechanisms.
An antibiogram is performed on a sample from your patient’s wound. The causative agent is found to be resistant to methicillin and vancomycin. This indicates that
A) her infection is untreatable and will likely be fatal within a few days.
B) antibiotics such as linezolid, daptomycin, or tigecycline are needed to treat her.
C) she likely acquired the organism in a community setting rather than in the hospital.
D) the causative organism is likely a member of her intestinal normal microbiota.
E) the causative organism does not produce the protein coagulase.
The fact that your patient has a high fever, a rash and muscle aches suggests the possibility of toxic shock syndrome, which means that the causative agent of her infection is
A) an endotoxin-producing S. aureus strain.
B) a toxin-producing S. epidermidis strain.
C) producing a capsule and forming a biofilm.
D) a superantigen-producing S. aureus strain.
E) a superantigen-producing S. epidermidis strain.
You are extremely concerned, because the laboratory reports that the organism cultured from your patient’s wound is capable of digesting collagen and fibronectin. Why are you worried about this?
A) These are structural components of tissue. Their digestion means that not only could the organisms spread easily, but also important structures such as tendons could be destroyed.
B) This would indicate that the organism is capable of forming biofilms and it is very difficult to eliminate biofilms once they have developed, because of resistance.
C) This would indicate that the bacterium is a lysogen, containing viral DNA conferring new characteristics on the organism. Bacteriophages pose an additional health risk to your patient.
D) These are structural components specifically of the heart. Their digestion means that the patient is at risk of heart failure, which will prove fatal.
E) This would indicate that the pathogen has the ability to break down activated complement proteins, thereby avoiding the innate immune defenses and allowing it to persist.
Wound infections are commonly caused by Staphylococcus species, common inhabitants of the nostrils and the skin. These organisms are
A) Gram-positive, pyrogenic, facultative anaerobes.
B) Gram-negative, pyogenic, facultative anaerobes.
C) Gram-positive, pyogenic, obligate aerobes.
D) Acid-fast, pyrogenic, obligate aerobes.
E) Gram-positive, pyogenic, facultative anaerobes.
You are given a prescription for both a penicillin derivative AND a β-lactamase inhibitor. Why are you given these medications?
A) Both P. multicoda and B. henselae produce β-lactamases. They are thus treated with β-lactamase-inhibiting medications. In addition, skin microbiota such as S. epidermidis respond to penicillins.
B) Both P. multicoda and B. henselae respond to penicillin derivatives. In addition, some bite wounds are infected with strains of β-lactamase-producing Staphylococcus aureus.
C) Both P. multicoda and B. henselae are encapsulated, so respond well to penicillin derivatives. In addition, some bite wounds are infected with strains of β-lactamase-producing Staphylococcus epidermidis.
D) The causative organisms of cat bite infections and bartonellosis are not well characterized. For this reason, penicillin derivatives and inhibitors of these medications are given synergistically.
E) Both P. multicoda and B. henselae respond to penicillin derivatives. In addition, some bite wounds are infected with strains of β-lactamase-producing Streptobacillus moniliformis.