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
Mention 4 bacterial genera that are obligate anaerobes!
Clostridium, Bacteroides, Prevotella, Porphyromonas, Fusobacterium, Actinomyces, Bifidobacterium, Peptostreptococcus, Propionibacterium
How long does immunity against scarlet fever exist? Which immune effector mechanism is involved?
Life-long immunity. Antitoxic antibodies are involved.
Mention at least 3 drugs which may be effective to treat infections caused by Pseudomonas aeruginosa!
certain penicillins: piperacillin/tazobactam combination a 3rd generation cephalosporin: ceftazidim a 4th generation cephalosporin: cefepime certain aminoglycosides: gentamycin, amikacin carbapenems: imipenem, meropenem
Which antibacterial drug is the first choice in serious infections caused by methycillin resistant Staphylococcus aureus (MRSA) strains?
glycopeptides (vancomycin, teicoplanin)
How can be Chlamydiae and Rickettsiae cultivated?
These are obligate intracellular bacteria, can be cultured in experimental animals, embryonated eggs, and cell culture
Mention 3 antituberculotic drugs that are of first choice against Mycobacterium tuberculosis!
- isoniazid (INH),
- pyrazinamid,
- rifampin,
- (ethambutol, streptomycin)
What is the reservoir and what is the vector for Borrelia recurrentis?
Reservoir: human; vector: louse
Which are the two different kinds of antibodies used in the diagnosis of syphilis? Give examples for tests demonstrating them!
Reagin (nonspecific antibody) – RPR, VDRL (flocculation tests) Immobilisin (specific antibody) – TPHA (T. pallidum hemagglutination), FTA-ABS (fluorescent treponemal assay – with antibody absorption), TPI (T. pallidum immobilisation test),
Which capsular serotype is included in the vaccine against Haemophilus influenzae?
type b
Mention 3 diseases that are frequently caused by Streptococcus pneumoniae!
- Pneumonia,
- meningitis,
- sinusitis,
- otitis media,
- sepsis, (ulcus serpens corneae)
Mention one aerobic and one anaerobic bacterium of the normal flora of the skin!
aerobic: Staphylococcus epidermidis anaerobic: Propionobacterium acnes
Which assays should be done in the lab in order to prove diphtheria?
Smears of the throat swab should be stained with methylene blue or Neisser stain; bacteria are cultured on Löffler’s or tellurite (Clauberg) medium; toxin production must be demonstrated by agar precipitation ( ELEK-test)
Mention 3 important bacteria involved in nosocomial (hospital-acquired) infections!
- Staphylococcus aureus,
- Enterococcus faecalis,
- Pseudomonas aeruginosa,
- Escherichia coli
Which is the most important gas gangrene Clostridium? What is its main virulence factor?
Clostridium perfringens alpha-toxin (lecithinase)
Give two genuses for each category of bacteria! Gram positive aerobic: Gram positive anaerobic:
Gram positive aerobic: Staphylococcus, Streptococcus, Bacillus, Corynebacterium Gram positive anaerobic: Clostridium, Actinomyces, Propionibacterium, Lactobacillus
Which product of Streptococcus pyogenes has a major pathogenic role in poststreptococcal diseases?
M protein: may induce hypersensitivity reactions
Specify at least 2 of the most important manifestations of disseminated gonorrhoeal infections!
arthritis, skin lesions, (endocarditis, meningitis)
What is the mechanism of action of the botulinus toxin?
Blocks release of acetylcholine in peripheral nerve synapses;
What are the main symptoms in the different stages of syphilis?
Primary syphilis: nontender ulcer (hard chancre)
Secondary lesions: maculopapular rash on skin, and condylomata lata on mucous membranes
Tertiary stage: granulomas (gummas), central nervous system involvement (tabes dorsalis, paralysis progressiva), cardiovascular lesions (aortitis, aortic aneurysm)
Mention a toxin-mediated streptococcal disease, specify the name of the toxin and its mechanism of action!
Scarlet fever - erythrogenic toxin – superantigen causing capillary destruction
What are the possible portals of entry of Francisella tularensis? Specify at least 4!
tick bite, mucous membranes, skin abrasions, resp. tract, gastroint. tract
What is the principle of the treatment for cholera?
Rapid intravenous or oral replacement of the lost fluid and ions. (Administration of isotonic maintenance solution should continue until the diarrhea ceases.) In severe cases: administration of tetracycline (in addition to rehydration).
What kind of therapy is used to treat botulism?
Treatment: respiratory support + trivalent antitoxin
What is the advantage and disadvantage of the FTA-ABS syphilis serologic test compared to the VDRL test?
Specific (treponemal) tests such as FTA-ABS are more specific, but they can not be used to follow the efficacy of treatment (because the specific antibodies persist even after effective eradication of bacteria)
What is the drug of first choice in Streptococcus pyogenes infection?
Penicillin-G
Mention an antibacterial drug active against chlamydial infections!
Tetracycline, erythromycin, azithromycin
The most frequent causative agent of urinary tract infections is:
Escherichia coli
What is the mechanism of action of the diphtheria toxin?
Inhibits protein synthesis. Inhibits peptide elongation in eukaryotic ribosomes by ADP ribosylation of EF-2 (elongation factor-2)
Mention 2 toxin-mediated staphylococcal diseases!
toxic shock syndrome (TSS), scalded skin syndrome, food poisoning
Mention 3 Clostridium species causing gas gangrene! How are they acquired?
Clostridium perfringens, C. novyi, C. septicum, C. histolyticum, C. tertium, C. bifermentans, C. sporogenes The site of infection is usually a wound that comes into contact with Clostridium spores that germinate in an anaerobic environment.
What are the reservoir and vector of Rickettsia typhi infections?
reservoir: rodents; vector: flea
Why is multi-drug therapy used for tuberculosis?
To prevent the overgrowth of drug-resistant mutants during the long treatment period (if bacteria resistant to one drug emerge, they are most probably inhibited by the other drugs).
Which bacteria cause most frequently typhoid fever and enteric fever, respectively?
Salmonella typhi (typhoid) Salmonella paratyphi A, B, C (enteric fever)
How can one demonstrate the presence of Mycobacterium tuberculosis in clinical samples?
Acid-fast staining (Ziehl-Neelsen) Culture on selective media (Löwenstein-Jensen agar, liquid BACTEC medium) PCR amplification of bacterial DNA
What diseases may be associated with Helicobacter pylori? Specify at least 3!
Gastritis, peptic and duodenal ulcers, gastric carcinoma, MALT lymphoma
Mention 3 bacterial species belonging to different genera that cause enteritis or enterocolitis!
Campylobacter jejuni, Escherichia coli, Salmonella enteritidis, Shigella, Yersinia enterocolitica
Give two genuses for each category of bacteria! Gram negativ aerobic: Gram negativ anaerobic:
Gram negativ aerobic: Vibrio, Neisseria, Haemophilus Gram negativ anaerobic: Bacteroides, Prevotella, Porphyromonas, Veillonella
List 3 important virulence factors of Bordetella pertussis!
- filamentous hemagglutinin,
- pertussis toxin,
- adenylate-cyclase toxin,
- tracheal cytotoxin
Mention 2 antibiotics which can be used in the empirical treatment against Gram negative obligate anaerobic bacteria!
Metronidazol, amoxicillin + clavulanic acid, imipenem
What is the drug of first choice in the treatment of syphilis?
penicillin G
Which are the portals of entry of Bacillus anthracis?
Skin, lungs, gastrointestinal tract
Which antibacterial drug is the first choice in serious infections caused by methycillin sensitive Staphylococcus aureus (MSSA) strains?
oxacillin (cloxacillin, flucloxacillin)
Mention four E. coli pathogenetic groups involved in enteric diseases!
- Enteropathogenic E. coli (EPEC)
- Enterotoxic E. coli (ETEC)
- Enteroinvasive E. coli (EIEC)
- Enterohemorrhagic E. coli (EHEC)
- Enteroaggregative E. coli (EAggEC)
What is (are) the major causative agent(s) for subacute bacterial endocarditis?
Viridans streptococci
List the 4 Shigella species causing human disease!
- Shigella dysenteriae,
- S. flexneri,
- S. boydii,
- S. sonnei
How can be tetanus prevented in patients who have wounds possibly contaminated with C. tetani spores?
Wound should be cleaned and debrided; tetanus toxoid booster injection given; tetanus immunoglobulin (TETIG) in previously unvaccinated patients and in case of heavy contamination of wound; penicillin may be added prophylactically
What is the causative agent of epidemic typhus?
Rickettsia prowazekii
Mention an antibacterial drug effective against Mycoplasma pneumoniae infections!
Erythromycin, azythromycin, tetracycline
What is the patomechanism of post-streptococcal glomerulonephritis?
type III hypersensitivity (immune complexes)
List 3 diseases caused by Streptococcus pyogenes in the skin or in subcutaneous tissues!
impetigo (pyoderma), cellulitis, erysipelas, fasciitis, myositis
What is the reservoir of Mycobacterium tuberculosis?
human
Mention a bacterial pathogen which eludes the host immune response by frequent antigenic changes!
Borrelia recurrentis, Neisseria gonorrhoeae
What kind of immunity develops after Neisseria gonorrhoeae infection?
Partial immunity of short duration; no protection from reinfection
What is the causative agent of febris recurrens (recurrent fever)?
Borrelia recurrentis
Which two diseases are caused by Rickettsia prowazekii?
Louse-borne epidemic typhus Recurrent form: Brill-Zinsser disease
Mention 2 obligate intracellular bacterial genuses!
Rickettsia, Chlamydia, (Coxiella, Ehrlichia)
Mention 4 bacteria causing atypical pneumonia!
- Chlamydia pneumoniae
- Chlamydia psittaci
- Coxiella burnetii
- Mycoplasma pneumoniae
- Legionella pneumophila
How can we identify the source of infection in a staphylococcal food poisoning?
by phage typing
Which 2 diseases are caused by E. coli O157:H7?
- hemorrhagic colitis +/-
- HUS (hemolytic uraemic syndrome)
What is the precise definition of bacterial food poisoning?
Acute disease, usually with vomiting and diarrhea, caused by preformed toxins produced by bacteria contaminating the food. The period between consumption of food and the appearance of symptoms is short (< 4-6 hours).
What is the reservoir of Leptospira interrogans?
rodents, household animals (dog, swine etc.)
Mention 4 diseases that are frequently caused by Pseudomonas aeruginosa!
- urinary tract infections wound infections (burns)
- pneumonia,
- sepsis (immunosupression)
- otitis externa
What are the 2 distinct forms of leprosy?
- Tuberculoid,
- lepromatous forms
Mention 3 Gram-negative bacteria belonging to different genera causing zoonosis!
- Brucella,
- Francisella tularensis,
- Yersinia pestis,
- Pasteurella
Mention 3 toxic products produced by Staphylococcus aureus!
- TSST (toxic shock syndrome toxin),
- enterotoxin,
- exfoliatin,
- leukocidins,
- hemolysins
What is the reservoir of atypical Mycobacteria?
environment (soil, water)
In which disease is Staphylococcus saprophyticus considered an obligate pathogen!
cystitis in young women
What is the causative agent of febris undulans (undulant fever)?
Brucellae
What is the site of entry of Neisseria meningitidis infection? Which diseases are caused by this bacterium?
The site of entry is the nasopharynx (transmitted by airborne droplets). Meningococcemia (characterized by skin lesions), and acute (purulent) bacterial meningitis.
What is the main immune defense mechanism against Mycobacterium tuberculosis?
activated macrophages
Which 3 bacterial species are the most important causative agents of meningitis among babies (> 1 month of age) and children?
Neisseria meningitidis, Haemophilus influenzae, Streptococcus pneumoniae
Which bacterium has the highest germ number in the colon?
Bacteroides fragilis
Why are penicillins not effective against Mycoplasma pneumoniae infections?
Because of the absence of a cell wall, penicillins are ineffective (penicillins inhibit cell wall synthesis)
Mention 3 enzymes produced by Streptococcus pyogenes that enhance the spread of the bacterial infection in the body!
Streptokinase (fibrinolysin), hyaluronidase, streptodornase (DNAse)
Mention 4 diseases caused by Haemophilus influenzae!
purulent meningitis epiglottitis (obstructive laryngitis) otitis media and sinusitis pneumonia (cellulitis, arthritis)
What is the major manifestation of Neisseria gonorrhoeae infection in newborns? How can it be prevented?
Blenorrhoea (ophtalmia) neonatorum, silver acetate eye drops or erythromycin ointment
What feature of Mycobacteria make them acid fast?
The cell envelope contains a high amount (60 – 70 %) of complex lipids: mycolic acid, cord factor. Once the cells are stained (by carbol-fuchsin) they resist decolorisation by acid-ethanol.
What are the main symptoms of tetanus infection? Specify at least 3!
Spastic paralysis: muscle spasms; lockjaw(trismus), rhisus sardonicus (grimace of the face), opisthotonus (spasm of the back); respiratory paralysis
Mention at least 3 major virulence factors of Neisseria gonorrhoeae!
pilus, outer membrane proteins, LOS (lipooligosaccharide), IgA protease
What is the causative agent of Lyme disease?
Borrelia burgdorferi
