Microbiology Flashcards
When should a sore throat be considered a medical emergency?
when combined with stridor or respiratory difficulty
What are the causes of inflammation by non-infectious means?
uncommon but include physical irritation eg from GORD; chronic irritation from cigarette smoke; alcohol or hayfever
Who do acute throat infections most common affect?
those aged 5-10 a nd 15-25`
What are the complications of a sore throat?
otitis media; peri-tonsillar abscess (quinsy); parapharyngeal abscess and mastoiditis
What should be suspected if sore throad and lethargy persist into the second week in 15-25 yos?
infectious mononucleosis
What are the causes for referral or admission with a sore throat?
if throat cancer is suspected; pain on swalling/dysphagia for more than 3 weeks; red or red and white patches or ulceration or swelling of the oral/pharyngeal mucosa persists for more than 3 weeks
What score should be used to assist decision on whether to give an antibiotic?
Centor clinical prediction score
What are the components of the Centor score?
tonsillar exudate; tender anterior cervical lymph nodes; hx of fever; absence of cough
What is the most common cause of bacterial sore throad?
step. pyogenes
what is the treatment for strep. pyogenes?
penicillin
What is seen on microbiology of strep. pyogenes?
gram positive cocci in chain; beta-haemolysis (complete)
What are the late complications of strep. sore throat?
rheumatic fever; glomerulonephritis
What are the signs of rheumatic fever?
fever; arthritis and pancarditis
What are the signs of glomerulonephritis?
haematuria; albuminuria and oedema
When does rheumatic fever arise after strep throat?
3 week post
When does glomerulonephritis arise after a strep throat?
1-3 weeks post
What are the features of Diphtheria?
severe sore throat with a grey white (pseudo) membrane across the pharynx
How does the organims cause illness?
a potent exotoxin
Why is diphtheria so serious?
the exotoxin is cardiotoxic and neurotoxic
What is the vaccine for diptheria made from?
toxoid
What is the treatment for diphtheria?
antitoxin and supportive and penicillin/erythromycin
What are the signs of candida/thrush?
white patches on red, raw mucous membranes in throat/mouth
What is the treatment for candida?
nystatin
What is acute otitis media?
a URTI involving the middle ear by extension of infection up the eustachian tube
Who gets otitis media?
infants and children
What are infections ofr the middle ear often caused by?
viral with bacterial secondary infection
What are the most common bacteria causing infections of the middle ear?
haemophilus influenzae; strep. pneumoniae; strep. pyogenes
How can a sample be obtained for infections of the middle ear?
swab of pus if eardrum perforates, otherwise samples cant be obtained
What is the first line antibiotic for infections ofr the middle ear?
amoxicillin
What is second line antibiotic for middle ear infefctions?
erythromycin
What are the signs of acute sinusitis?
mild discomfort over frontal or maxillary sinuses due to congestion often seen with URTI
What would indicate a secondary bacterial infection with acute sinusitis?
severe pain and tenderness with purulent discharge
When should antibiotics be given with sinusitis?
for severe/deteriorating cases of more than 10 days
What is the first line antibiotic for sinusitis?
penicillin V
What is the second line antibiotic for sinusitis?
doxycycline
Who should doxycycline NOT be given to?
children
What is otitis externa?
inflammation fo the outer ear canal
What are the signs of otitis externa?
redness and swelling of the skin of the ear canal; itchiness; sore and painful; discharge or increased wav
What is malignant otitis?
an extension of otitis externa in to the bone surrounding the ear canal which is fatal without treatment
What bones does malignant otits affect?
mastoid and temporal bones
What are the symptoms and signs of malignant otits?
pain and hedache, more severe than clinical signs would suggest; granulation tissue at bone-cartilage junction of ear canal; exposed bone in the ear canal; facial nerve palsy
What is facial nerve palsy?
drooping face on the side of the lesion
What are the investigations for malignant otitis?
PV; CRP; imagin; biopsy and culture
What is the most common bacteria in malignant otitis?
pseudomonas
What are the risk factors for malignant otitis?
DM; PMH of radiotherapy
What are the bacterial causes of otitis externa?
staph. aureus; proteus; pseudomonas; aspergillus; candida
What is the treatment for otitis externa?
topical aural toilet
When should a swab and prescription be done for otitis externa?
unresponsive and severe cases
What might you prescribe for otitis externa depending on the culture results?
topical clotramizole or gentamicin drops
What is the classic triad seen in infectious mononucleosis?
fever; pharyngitis and lymphadenpathy
What are other signs of glandular fever?
jaundice/hepatitis; rash; leucocytosis; presence of stypical lymphocytes in blood film; splenomegaly; palatal petechiae
What antibiotic results in a rash with glandular fever?
ampicillin or amoxicillin
What do the atypical lymphocytes seen with glandular fever look like?
activated cytotoxic T lymphocytes- larger, irregular nucleus and high level of ribosomes
What are complications of glandular ever?
anaemia; thrombocytopania; splenic rupture; upper airway obstrucition; increased risk of lymphoma esp. in immunosuppressed
What should be avoided following glandular fever and why?
avoid sports for 6 weeks- splenic rupture
What virus causes glandular fever?
EBV
What are the 2 phases of primary infection with EBV?
early childhood- rarely results in glandular fever; in over 10s often causes
What is the therapy for glandular fever?
ebd rest; avoid sport; paracetamol
How is glandular fever comfrimed in the lab?
EBV IgM; monospot- heterophile antibody; blood count and film; LFTs
How can you differentiate between EBV and CMV which cause very similar disease??
no heterophile antibody and fewer atypical lymphocytes
When is type 1 HSV typically acquired?
childhood
What does type 1 HSV cause?
oral lesions
How is HSV transferred?
salivary contact
What disease can occur with primary infection of HSV type 1?
primary gingivostomatitis
What are the signs of primary gingivostomatitis?
systemic upset-fever, local lymphadenopathy; lips, buccal mucosa, hard palate affected with vesicles and ulcers
How is primary gingivostomatitis treated?
aciclovir
Where is herpes held latent?
inactive form of virus in sensory nerve cells of trigeminal ganglia (nerve that serves the area of the mouth)
Does aciclovir prevent latency?
no
What is the percentage of people that get clinical reoccurences with HSV1?
half
What would recurrent intra-oral lesions indicate?
Rarely cause by HSV so likely to be something else
What is herpetic whitlow?
HSV infected in fingers
How is HSV confirmed in the lab?
swab of lesion and viral DNA detected by PCR
What is a complication of HSV in the CNS?
herpes simplex encephalitis
What causes herpangina?
coxsackie virus-enterovirus
What are the signs of herpangina?
vesicles/ulcers on soft palate
What patient group gets herpangina?
children
What virus causes hand, foot and mouth disease?
coxsakcie virus
What are apthous ulcers?
recurring painful ulcers of the mouth that are round or ovoid and have inflammatory halos- each ulcer lasts less than 3 weeks; absence of systemic disease
What causes apthous ulcers?
non-viral, self limiting
What is the triad seen with Behcets disease?
recurrent oral ulcers; genital ulcers and uceitis
Where is Behcets most common?
middle east and asia
What is the triad foudn with Reiters ?
Noninfectious urethritis
Arthritis
Conjunctivitis
What are the cahracteritics of a chancre?
painless indurated ulcer at site of entry of Treponema pallidum
What is a chancre a sign of?
syphilis
