Department questions Flashcards
Enumerate the mechanisms of resistance of Staphylococcus aureus to beta-lactam containing antibiotics.
This resistance is due to B-lactamase production.
MRSA: there is a change to the penicillin-binding protein which is the binding site for the antibiotic on the organism’s cell wall.
Vancomycin-resistant S. aureus: very serious and aggressive situation
Enumerate invasive infections caused by streptococcus pyogenes
Puerperal fever: life threatening infection of endometrium post birth can lead to septicemia and toxic shock syndrome
Acute endocarditis
Necrotizing fasciitis
Toxic shock syndrome
Pregnant females colonized with Streptococcus agalactiae at the end of the third trimester are given ampicillin during delivery.
To prevent transfer of bacteria during delivery to the infant. ampicillin is give for colonized mother
Enumerate the types of diarrhoeagenic Escheria coli and give the mechanism of action of each type
Entero-pathogenic E.coli: adhere to mucosa—> interfere with water absorption
Entero-invasive E.coli: Invasion of mucosa without toxin production
Entero-toxigenic E.coli: Productions of enterotoxins
Enterohaemorrhagic E.coli: Production of shiga-like-toxin
Entero-aggregative E.coli: Adhere to mucosa by aggregative fimbria and production of enterotoxin
Enumerate 3 complications of Typhoid fever
Perforation of bowel and hemorrhage from bowel ulceration
Why : Direct person-to-person transmission of Vibrio cholerae is not common.
Vibrios are sensitive to acid and most die in the stomach -> high infectivity dose is required
so direct person-to-person spread is not common
Enumerate the autoimmune diseases that may complicate Campylobacter enteritis
Guillain-Barre syndrome: antibodies against disease cross react with antigens on neurons
Reactive arthritis
Reiter’s disease: triad of arthritis, conjunctivitis and urethritis
Give reason(s): Most Haemophilus influenzae infections occur in children between 6 months and 6 years.
decline of maternal IgG with
inability of child to generate antibodies against polysaccharide capsular (Tl) antigen
Enumerate the Modes of transmission of Malta fever.
O Ingestion of contaminated unpasteurized milk or milk products
® Direct contact through skin abrasions during handling of infected animals or their discharges
© Inhalation of infected aerosol during handling of Infected animals
Mention the causative organism and the mode of transmission of chancer
Causative organism: syphilis
mode of transmission: sexually and transplacentaly
Give reason the genus Mycoplasma is resistant to beta-lactam antibiotics
Mycoplasmas are bacteria without cell wall -> lack of cell wall renders these organisms:
O Resistant to antibiotics which inhibit cell wall synthesis (e.g. beta-lactam antibiotics)
Give reason(s): Acute rheumatic fever may occur following streptococcal pharyngitis infection.
It is due to the formation of antibodies to streptococcal M protein which cross react with antigens of joint, heart and brain tissue.
Interpret the following test:
Optochin-sensitive bacterial colonies with alpha-hemolysis on blood agar.
Streptococcus pneumoniae
Interpret the following test:
Optochin resistant bacterial colonies with alpha-hemolysis on blood agar.
Viridians streptococcus
Pregnant females colonized with Streptococcus agalactiae at the end of the third trimester are given ampicillin during delivery.
to reduce neonatal sepsis
