Exam 2: Microbiology

Question 1

What are the main targets of antibiotics?

Answer 1

Ribosomes, Chromosomes, plasmids, and the cell wall

Question 2

What is the main difference between gram negative and gram positive cells?

Answer 2

Gram positive cells have a thick cell wall.

Gram negative Cells have a thin cell wall, but two lipid bilayers

Question 3

What is the main difference between bacterial and mammalian cells?

Answer 3

Bacteria have a rigid cell wall external to the cell membrane

Question 4

What is unique about mycoplasma bacteria?

Answer 4

They lack a cell wall

Question 5

What is unique about the chlyamydiae bacteria?

Answer 5

Their cell wall structure differs from other bacteria because it is made from lipopolysaccharide instead of peptidoglycan

Question 6

What is the difference between a primary and secondary infection?

Answer 6

A primary infection is caused by an overgrowth of normal body flora, and a secondary infection is an infection is bacteria not normally on the body

Question 7

Is staphylococcus aureus gram negative or positive? Is it normal body flora? Is it pathogenic?

Answer 7

• Gram positive cocci
• Normal skin flora in nose, respiratory tract, and skin
• can be pathogenic and cause abscesses, food poisoning, sinusitis, TSS, osteomyelitis, endocarditis, meningitis, sepsis, etc.

Question 8

Is Escherichia coli gram negative or positive? Is it normal body flora? Is it pathogenic?

Answer 8

• Gram negative bacilli
• Normal flora in the GI tract
• Can be pathogenic and cause food contamination, UTI, cystitis, pyelonephritis, PNA, and meningitis

Question 9

Is streptococcus gram negative or positive? Is it normal body flora? Is it pathogenic?

Answer 9

• Gram positive cocci
• Normal flora in nasopharynx, large intestine, and vagina
• Can be pathogenic and cause PNA, meningitis, cellulitis, endocarditis, sepsis, otitis media, etc

Question 10

Is pseudomonas gram negative or positive? Is it normal body flora? Is it pathogenic?

Answer 10

• Gram negative bacilli
• Normal flora in large intestine, pharynx, and mouth
• Opportunistic pathogen that may cause endophthalmitis, endocarditis, meningitis, PNA, and septicemia
• Common in IVDA, cystic fibrosis, cancer, AIDS, and organ transplant

Question 11

Is Helicobacter pylori gram negative or positive? Is it normal body flora? Is it pathogenic?

Answer 11

• Gram negative, helical
• Normal flora in upper GI tract
• Can be pathogenic and cause gastritis, peptic ulcers, and gastric adenocarcinoma
• YOU MUST TREAT H. PYLORI

Question 12

Is Borrelia Burdgorferi gram negative or positive? Is it normal body flora? Is it pathogenic?

Answer 12

• Neither gram negative or positive
• Not normal flora
• Causes Lyme disease

Question 13

Is clostridium difficile gram negative or positive? Is it normal body flora? Is it pathogenic?

Answer 13

• Gram positive anaerobe
• Normal flora in large intestine
• Can cause pseudomembranous colitis, superinfection
• those taking antibiotics and elderly in nursing homes are at high risk

Question 14

Is chlamydiae gram negative or positive? Is it normal body flora? Is it pathogenic?

Answer 14

• Gram negative, obligate intracellular cocci
• Not normal flora
• Can cause STD and Community acquired PNA
• C. Pneumoniae and C. Trachomitis are the major human pathogens

Question 15

Is Neisseria Gonorrhoeae gram negative or positive? Is it normal body flora? Is it pathogenic?

Answer 15

• Gram negative, aerobic diplococci
• Not normal flora
• Pathogenic to genitals, throat, and eyes. Untreated can lead to PID, septic arthritis, and vision loss