Clinical Bacteriology

Question 1

Mention 5 diseases that are frequently caused by Staphylococcus aureus!

Answer 1

folliculitis, furunculus, bullous impetigo, osteomyelitis, food poisoning, pneumonia etc.

Question 2

Mention 2 toxin-mediated staphylococcal diseases!

Answer 2

toxic shock syndrome (TSS), scalded skin syndrome, food poisoning

Question 3

Mention 3 toxic products produced by Staphylococcus aureus!

Answer 3

TSST (toxic shock syndrome toxin), enterotoxin, exfoliatin, leukocidins, hemolysins

Question 4

Which is the most virulent species of the Staphylococcus genus?

Answer 4

S. aureus

Question 5

Which enzymatic virulence factor is characteristic exclusively for Staphylococcus aureus?

Answer 5

exocoagulase

Question 6

Which biochemical test can be used to differentiate staphylococci from streptococci?

Answer 6

catalase test

Question 7

Which antibacterial drug is the first choice in serious infections caused by methycillin sensitive Staphylococcus aureus (MSSA) strains?

Answer 7

oxacillin (cloxacillin, flucloxacillin)

Question 8

Which antibacterial drug is the first choice in serious infections caused by methycillin resistant Staphylococcus aureus (MRSA) strains?

Answer 8

glycopeptides (vancomycin, teicoplanin)

Question 9

In which disease is Staphylococcus saprophyticus considered an obligate pathogen?

Answer 9

cystitis in young women

Question 10

Which cell constituents determine the group-specific, and the type specific antigens of Streptococcus pyogenes, respectively?

Answer 10

group specific: C- polysaccharide
type specific: M protein

Question 11

Mention 3 enzymes produced by Streptococcus pyogenes that enhance the spread of the bacterial infection in the body!

Answer 11

Streptokinase (fibrinolysin), hyaluronidase, streptodornase (DNAse)

Question 12

List 3 diseases caused by Streptococcus pyogenes in the skin or in subcutaneous tissues!

Answer 12

impetigo, erysipelas, cellulitis, necrotizing fasciitis, myonecrosis

Question 13

Mention a toxin-mediated streptococcal disease; specify the name of the toxin and its mechanism of action!

Answer 13

Scarlet fever - erythrogenic toxin – superantigen causing capillary destruction Streptococcal toxic shock syndrome (TSS) – TSST - superantigen

Question 14

Mention 2 poststreptococcal diseases!

Answer 14

Glomerulonephritis, rheumatic fever, (erythema nodosum, chorea minor)

Question 15

Which product of Streptococcus pyogenes has a major pathogenic role in poststreptococcal diseases?

Answer 15

M protein: may induce hypersensitivity reactions

Question 16

How long does immunity against scarlet fever exist? Which immune effector mechanism is involved?

Answer 16

Life-long immunity. Antitoxic antibodies are involved.

Question 17

What is the drug of first choice in Streptococcus pyogenes infection?

Answer 17

Penicillin-G, penicillin V / amoxicillin

Question 18

What is the patomechanism of post-streptococcal rheumatic fever?

Answer 18

type II hypersensitivity (cytotoxic antibodies)

Question 19

What is the patomechanism of post-streptococcal glomerulonephritis?

Answer 19

type III hypersensitivity (immune complexes)

Question 20

Which Streptococcus species plays major role in the meningitis of newborn babies?

Answer 20

Group B Streptococcus (S. agalactiae)

Question 21

What is (are) the major causative agent(s) for native valve infective endocarditis?

Answer 21

Viridans streptococci

Question 22

Mention 2 diseases that are frequently caused by enterococci!

Answer 22

urinary tract infections, endocarditis, intraabdominal and pelvic infections

Question 23

What are the specific morphologic features of Streptococcus pneumoniae?

Answer 23

Gram positive diplococcus, lancet shape, capsule.

Question 24

Mention 3 diseases that are frequently caused by Streptococcus pneumoniae!

Answer 24

Pneumonia, meningitis, sinusitis, otitis media, sepsis

Question 25

What fast diagnostic procedure can be used in acute Neisseria gonorrhoeae infection?

Answer 25

Demonstration of bacteria (intracellular in PMNs) from urethral discharge by Gram or methylene blue stain; PCR amplification of bacterial DNA

Question 26

What kind of immunity develops after Neisseria gonorrhoeae infection?

Answer 26

Partial immunity of short duration; no protection from reinfection

Question 27

Specify at least 2 of the most important manifestations of disseminated gonorrhoeal infections!

Answer 27

arthritis, skin lesions, (endocarditis, meningitis)

Question 28

What is the major manifestation of Neisseria gonorrhoeae infection in newborns? How can it be prevented?

Answer 28

Blenorrhoea (ophtalmia) neonatorum; silver acetate eye drops or erythromycin ointment

Question 29

Mention at least 3 major virulence factors of Neisseria gonorrhoeae!

Answer 29

pilus, outer membrane proteins, LOS (lipooligosaccharide), IgA protease

Question 30

Mention at least 2 major virulence factors of Neisseria meningitidis!

Answer 30

polysaccharide capsule, LOS, IgA protease

Question 31

What is the site of entry of Neisseria meningitidis infection? Which diseases are caused by this bacterium?

Answer 31

The site of entry is the nasopharynx (transmitted by airborne droplets). Meningococcemia and acute (purulent) bacterial meningitis.

Question 32

What kinds of prophylactic measures are available against Neisseria meningitidis infections?

Answer 32

Chemoprophylaxis: rifampin or ciprofloxacin. Vaccination: capsular polysaccharide (types A, C, Y and W135). Vaccine against type B: contains different recombinant proteins.

Question 33

Which rapid diagnostic methods can be used in the presumptive diagnosis of purulent bacterial meningitis?

Answer 33

Gram or methylene blue stain of CSF sediment Demonstration of bacterial capsular antigens by latex agglutination (from CSF) Polymerase chain reaction (PCR)

Question 34

What does the vaccine against Haemophilus influenzae contain?

Answer 34

type b capsular polysaccharide conjugated to a carrier protein

Question 35

Which are the portals of entry of Bacillus anthracis?

Answer 35

Skin, lungs, gastrointestinal tract

Question 36

Mention 3 important bacteria involved in nosocomial (hospital-acquired) infections!

Answer 36

Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, Clostridioides difficile