Clinical Bacteriology Flashcards
Mention 4 bacteria frequently causing sexually transmitted diseases (STD)!
Treponema pallidum, Neisseria gonorrhoeae, Haemophilus ducreyi, Chlamydia trachomatis, (Calymmatobacterium granulomatis)
What are the reservoir and vector of Rickettsia prowazekii infections?
reservoir: human; vector: louse
Mention 2 antibacterial drugs that are of first choice in early stage Lyme disease?
Tetracyclines, amoxicillin, cefuroxim
Which Streptococcus species plays major role in the meningitis of newborn babies?
Group B Streptococcus (S. agalactiae)
What is the most important virulence factor of Corynebacterium diphtheriae?
Diphtheria toxin
What can serve as source of infections caused by Pseudomonas aeruginosa?
Pseudomonas species are normally present in the environment and can be isolated from the skin, throat, and stool of some healthy persons. They often colonize hospital food, sinks, taps, mops, and respiratory equipment.
What disease is caused by Mycobacterium avium-intracellulare? What patients are characteristically susceptible to infection?
It causes TB, especially in immunosuppressed patients (such as AIDS patients).
What fast diagnostic procedure can be used in acute Neisseria gonorrhoeae infection?
Demonstration of bacteria (intracellular in PMNs) from urethral discharge by Gram or methylene blue stain; PCR amplification of bacterial DNA
Which 3 bacterial species are the most important causative agents of neonatal (< 1 month of age) meningitis?
Streptococcus agalactiae, E. coli, Listeria monocytogenes
What are the frequent sources of infection for Legionella pneumophila?
air conditionars, water taps, showers, evaporators, etc.
What are the most important extraintestinal infections caused by E. coli? Mention at least 3 of them!
urinary tract infections, neonatal meningitis, nosocomial wound infections
Which is the most virulent species of Staphylococcus?
S. aureus
What is the mechanism of action of cholera toxin?
Cholera toxin activates the adenylate cyclase enzyme in cells of the intestinal mucosa leading to increased levels of intracellular cAMP, and the secretion of large amount of water, Na+, K+, Cl-, and HCO3- into the lumen of the small intestine.
Which cell constituents determine the group-specific, and the type specific antigens of Streptococcus pyogenes, respectively?
group specific: C- polysaccharide type specific: M protein
How do humans acquire brucellosis? Where do the bacteria replicate in the human body?
Via contaminated milk products or through skin abrasions (contact with animals). Organisms spread to the mononuclear phagocytes of the reticuloendothelial system (lymph nodes, liver, spleen, bone marrow).
When syphilis is diagnosed in the lab, which antigens are used in the non-treponemal and in the specific treponemal antibody tests, respectively?
Non-treponemal antibody tests: cardiolipin Specific treponemal antibody tests: Treponema pallidum
Give 2 genuses for each category of bacteria! Gram positive coccus: Gram positive rod:
Gram positive coccus: Staphylococcus, Streptococcus Gram positive rod: Clostridium, Bacillus
What is the reservoir of Salmonella typhi?
humans (with disease, or healthy carriers)
Which antibacterial drugs should be administered in gastroenteritis caused by Salmonella?
Antibiotics are not usually necessary unless the infection is generalised. In case of extraintestinal infection (very young, very old or immunosuppressed patients): ampicillin, gentamicin, trimethoprim/sulfamethoxazole, or ciprofloxacin.
What are the reservoirs of the different Brucella species, respectively?
B. abortus: cattle B. melitensis: goat, sheep B. suis: swine B.canis: Dog
Give 2 genuses for each category of bacteria! Gram negative rod: Spirochetes:
Gram negative rod: E. coli, Salmonella, Shigella Spirochetes: Treponema, Borrelia, Leptospira
What is the first characteristic manifestation in the early phase of Lyme disease?
Erythema (chronicum) migrans
Mention 2 atypical Mycobacterium species!
M. kansasii, M. marinum, M. avium-intracellulare complex, M. fortuitum-chelonei complex
Mention 2 poststreptococcal diseases!
Glomerulonephritis, rheumatic fever, erythema nodosum, chorea minor.
Describe the color and the shape of Clostridia in a Gram stained smear of gas gangrene exudate!
Gram positive (dark blue) rod (it usually does not form spores in vivo)
Mention 2 bacteria causing intestinal infections which have animal reservoirs!
Salmonella (not Typhi and Paratyphi!), Campylobacter jejuni, Yersinia enterocolitica, Listeria monocytogenes, E. coli O157
Which 2 diseases are caused by Legionella pneumophila?
- legionellosis, legionnairs’ disease (atypical pneumonia) - Pontiac fever (mild, flu like illness without pneumonia)
Which rapid diagnostic methods can be used in the presumptive diagnosis of purulent bacterial meningitis?
Gram or methylene blue stain of CSF sediment Demonstration of bacterial capsular antigens by latex agglutination (from CSF)
Which disease is caused by Haemophilus ducreyi?
Chancroid (soft chancre or ulcus molle), which is an STD (sexually transmitted disease)
Which enzymatic virulence factor is characteristic exclusively for Staphylococcus aureus?
exocoagulase
What is the route of infection in Salmonella gastroenteritis?
Ingestion of contaminated food (such as eggs, cream, mayonnaise, creamed foods, etc.) containing a sufficient number of Salmonella.
Mention 2 bacteria causing aseptic (serous) meningitis!
Treponema pallidum, Leptospira interrogans, Borrelia burgdorferi
What is used for the laboratory diagnosis of relapsing fever?
Direct demonstration of bacteria from peripheral blood smear by microscopy (Giemsa stain or dark field illumination)
Mention 2 bacterial species belonging to different genera that cause bacillary dysentery
Shigella dysenteriae, (Shigella flexneri, Shigella boydii, Shigella sonnei), enteroinvasive E. coli (EIEC)
What is the causative agent of endemic typhus?
Rickettsia typhi
Mention an antibacterial drug active against rickettsial infections!
Tetracycline, chloramphenicol
What are the specific morphologic features of Streptococcus pneumoniae?
Gram positive diplococcus, lancet shape, capsule.
List the serotypes of Chlamydia trachomatis and the diseases caused by them!
Types A,B and C: trachoma (chronic conjunctivitis) Types D-K: genital tract infections (NGU, PID), inclusion conjunctivitis Types L1-L3: lymphogranuloma venereum (STD)
Which manifestations are characteristic for the late phases of Lyme disease?
Arthritis, cardiac manifestations (myocarditis, pericarditis) and neurological involvement (meningitis, peripheral neuropathies)
What are the modes of transmission for the 2 different epidemiologic forms of plague?
- Bubonic plague is transmitted by the bite of infected rat fleas from rats to humans. - Primary pneumonic plague spreads directly from human to human via respiratory droplets.
Mention at least 2 major virulence factors of Neisseria meningitidis!
polysaccharide capsule, LPS, IgA protease
What are the characteristics of Enterococci that can be used in their identification?
D group polysaccharide antigen; tolerance to bile and hydrolysis of esculin (BEA medium: bile esculin agar); growth in the presence of 6,5 % NaCl
When typhoid fever is suspected, what kinds of clinical samples should be used to isolate the causative agent in the first 2 weeks of the disease?
Blood, (bone marrow)
Mention 2 Gram-positive bacteria belonging to different genera causing zoonosis!
Listeria monocytogenes, Bacillus anthracis, Erysipelothrix rhusiopathiae
How long does immunity against diphtheria exist? Which immune effector mechanism is involved?
long lasting immunity; antitoxic antibodies
Explain whether or not antibiotic treatment is useful in botulism!
Not, because antibiotics are not effective against preformed toxins.
Mention 3 bacterium species causing food poisoning!
Staphylococcus aureus, Bacillus cereus, Clostridium perfringens, Clostridium botulinum, Vibrio parahaemolyticus, (Salmonella serotypes causing enterocolitis)
What are the main symptoms of botulism? Specify at least 3!
flaccid paralysis: diplopia (double vision), dysphagia (difficulty to swallow), dysphonia (hoarseness), respiratory paralysis.
What kinds of prophylactic measurements are available against Neisseria meningitidis infections?
Chemoprophylaxis: rifampin or ciprofloxacin. Vaccination: capsular polysaccharide (types A, C, Y and W135). No vaccine against type B!
Mention 5 diseases that are frequently caused by Staphylococcus aureus!
Impetigo, furunculus, pneumonia, osteomyelitis, food poisoning etc.
What is the patomechanism of post-streptococcal rheumatic fever?
type II hypersensitivity (cytotoxic antibodies)
Which bacterial species can cause hepatitis (jaundice)?
Leptospira interrogans
Mention 3 bacterial species belonging to different genera that are frequent causes of urinary tract infections!
E. coli, Klebsiella, Proteus, Pseudomonas aeruginosa, Enterococcus faecalis