841.The most common cause of traveller’s diarrheoa is
A.Rotavirus
B.E coli
C.Shigella
D.Giardia
E.Salmonella

842.Pneumocystis carinii
A.Produces pneumocystis pneumoniain normal persons
B.Causes a Ghon’s focus in the lung
C.Causes a patchy atelectasis
D.Is a fungus
E.Attaches selectively to type II alveolar cells

843.Tetanus toxin
A.Is composed of a light and heavy chain
B.Acts directly on motor neurons
C.Stimulates inhibitory neurons
D.Never affects BP
E.Is produced by gram negative rods

844.regarding streptococcal infections
A.commonly cause boils
B.do not produce glomerulonephritis
C.cause minimal destruction of host tissue
D.do not produce capsular virulence factors
E.streptococcus pneumoniae is the commonest cause of meningitis in children

845.In TB
A.Mycobacteria are aerobic, spore forming bacilli
B.CD4+ T cell result in formation of granulomas by killing macrophages
C.The major cause of tissue damage is granulomas
D.The granulomas in patients with AIDS are well formed
E.The CD8 T cells secrete cytokines inducing macrophage transformation

846.Streptococcus
A.Viridans is β haemolytic
B.Produces an endotoxin which causes scarlet fever
C.Causes erysipelas which involves significant tissue necrosis
D.Causes 50% of community acquired lobar pneumonias
E.Glomerulonephritis becomes chronic in less than 10% children

847.Clostridia
A.Perfringins produces toxin A
B.Tetani neurotoxin produces both a heavy and a light chain
C.Is a gram positive coccus that grows under both aerobic and anaerobic conditions
D.Botulinum releases a potent neurotoxin that causes convulsive contractions of skeletal muscles
E.Clostridial cellulites causes severe myonecrosis

848.Staphylococci
A.Are typical encapsulated diplococci
B.Produce multiple haemolytic toxins including α toxins
C.Rarely cause pyogenic infections in bone
D.Are the most common cause of hospital acquired infections
E.Lung infections are rarely opportunisitic

849.Mycobacteria tuberculosis
A.Are aerobic, non-spore forming, non-motilecocci
B.Induce type II hypersensitivity
C.Cause formation of epitheliod cell granulomae
D.Are killed by macrophages in primary infection
E.Induce formation of a Ghon complex after secondary infection

850.virulence factors of Staphinclude
A.surface proteins that adhere to host cell
B.enzymes that degrade host proteins
C.exfoliative toxins
D.enterotoxins that stimulate emetic receptors in abdominal viscera
E.all of the above

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