DIAGNOSTIC MICROBIOLOGY MAHON AND
LEHMAN COMPLETE COURSE REVIEW GUIDE
◉ What does pathogenic mean?
Answer: Capable of causing infectious disease
◉ What is a commensal organism?
Answer: An organism that grows in or on the host without causing
harm; also called normal flora
◉ Can the same organism be pathogenic in one circumstance and
commensal in another?
Answer: Yes
◉ Which host factors affect whether an organism becomes
pathogenic?
Answer: Overall health, immune function, previous pathogen
exposure, medical history, immunosuppressive medications, genetic
factors, and normal microbial flora
◉ What factors promote microbial growth and pathogenicity?
Answer: Food, acidity, temperature, time, oxygen, and moisture
,◉ What are major anatomic barriers against infection?
Answer: Intact skin, swallowing, cilia and hairs, coughing, and
gastrointestinal peristalsis
◉ What are major physiologic barriers against infection?
Answer: High or low pH, oxygen tension, lysozymes in saliva and
tears, normal flora, protease growth inhibitors, bile acids, and fatty
acids on skin
◉ What components of host defense are nonspecific or innate?
Answer: Inflammation, segmented neutrophils, normal flora, tears,
stomach acid, and cilia
◉ What components of host defense are specific or adaptive?
Answer: Cellular immunity from T lymphocytes and humoral
immunity from B lymphocytes
◉ What do B lymphocytes produce?
Answer: Antibodies that target specific antigens
◉ Which form of immunity provides the basis for vaccination?
Answer: Specific or adaptive immunity
, ◉ Which specimens or sites commonly contain normal flora?
Answer: Stool, sputum, skin, vagina, and urine
◉ Which sites are normally sterile?
Answer: Blood, cerebrospinal fluid, peritoneal fluid, bone marrow,
tissue, and joint fluid
◉ Which organisms are listed as normal flora of the nasopharynx?
Answer: Streptococci, Haemophilus, Neisseria, mixed anaerobes,
Candida, and Actinomyces
◉ Which organisms are listed as normal flora of the skin?
Answer: Staphylococci, streptococci, Corynebacteria,
Propionibacteria, and yeasts
◉ Which organisms are listed as normal flora of the upper bowel?
Answer: Enterobacteriaceae, enterococci, and Candida
◉ Which organisms are listed as normal flora of the lower bowel?
Answer: Bacteroides, Bifidobacteria, Clostridium, and
Peptostreptococci
LEHMAN COMPLETE COURSE REVIEW GUIDE
◉ What does pathogenic mean?
Answer: Capable of causing infectious disease
◉ What is a commensal organism?
Answer: An organism that grows in or on the host without causing
harm; also called normal flora
◉ Can the same organism be pathogenic in one circumstance and
commensal in another?
Answer: Yes
◉ Which host factors affect whether an organism becomes
pathogenic?
Answer: Overall health, immune function, previous pathogen
exposure, medical history, immunosuppressive medications, genetic
factors, and normal microbial flora
◉ What factors promote microbial growth and pathogenicity?
Answer: Food, acidity, temperature, time, oxygen, and moisture
,◉ What are major anatomic barriers against infection?
Answer: Intact skin, swallowing, cilia and hairs, coughing, and
gastrointestinal peristalsis
◉ What are major physiologic barriers against infection?
Answer: High or low pH, oxygen tension, lysozymes in saliva and
tears, normal flora, protease growth inhibitors, bile acids, and fatty
acids on skin
◉ What components of host defense are nonspecific or innate?
Answer: Inflammation, segmented neutrophils, normal flora, tears,
stomach acid, and cilia
◉ What components of host defense are specific or adaptive?
Answer: Cellular immunity from T lymphocytes and humoral
immunity from B lymphocytes
◉ What do B lymphocytes produce?
Answer: Antibodies that target specific antigens
◉ Which form of immunity provides the basis for vaccination?
Answer: Specific or adaptive immunity
, ◉ Which specimens or sites commonly contain normal flora?
Answer: Stool, sputum, skin, vagina, and urine
◉ Which sites are normally sterile?
Answer: Blood, cerebrospinal fluid, peritoneal fluid, bone marrow,
tissue, and joint fluid
◉ Which organisms are listed as normal flora of the nasopharynx?
Answer: Streptococci, Haemophilus, Neisseria, mixed anaerobes,
Candida, and Actinomyces
◉ Which organisms are listed as normal flora of the skin?
Answer: Staphylococci, streptococci, Corynebacteria,
Propionibacteria, and yeasts
◉ Which organisms are listed as normal flora of the upper bowel?
Answer: Enterobacteriaceae, enterococci, and Candida
◉ Which organisms are listed as normal flora of the lower bowel?
Answer: Bacteroides, Bifidobacteria, Clostridium, and
Peptostreptococci
