Medical Microbiology Flashcards
CAP antibiotic treatment
Low severity (CURB65 0-1): doxycycline PO 200mg stat then 100mg OD (5-7 days)
Moderate severity (CURB65 2-5): benpen IV 1.2- 4 hrly + doxycycline PO 200mg STAT then 100mg OD (7-10days in total IV and PO)
COPD infective exacerbation antibiotic treatment
doxycycline PO 200mg STAT then 100mg OD (5-7 days)
Uncomplicated UTI antibiotic treatment
Nitrofurantoin 50mg PO 6 hourly
Males: 7 days
Females: 3 days
Soft tissue infection antibiotic treatment
Non-severe: flucloxacillin PO 500mg 6hrly (7 days)
Severe: flucloxicillin IV 2mg 6 hrly (review IV after 5-7 days depending on response)
What is the effect of antibiotics on the gut and skin flora
broad spectrum abx suppress the normal gut flora
this allowed C Diff to develop
what is c diff
gram positive rod that produces an exotoxin which causes intestinal damage leading to PSEUDOMEMBRANOUS COLITIS
what is the leading cause of c diff
second and third generation cephalosporins
ceftriaxone, cefotaxima, cefoxitin
what is the diagnosis of c diff?
stool sample detecting the toxin
treatment of c diff
oral metronidazole for 10-14 days
meningococcal septicaemia/meningitis rash
petechial or purpuric rash
80-90% of patients
most commonly 4 to 18 hours after initial symptoms of illness
typically non-blanching
sepsis six
give oxygen (sats >94%)
give broad spectrum antibiotics (coamoxiclav IV and amikacin IV)
give IV fluid challenge
take blood cultures
measure serum lactate
measure hourly urine output
what is pyrexia of unknown origin (PUO)
a temperature over 38.3 for >3 weeks with no obvious source despite appropriate investigations
what are possible causes of PUO?
infections: abscesses, empyema, RF, TV, parasites, fungi
neoplasms: lymphomas
CT disease: RA, polymyalgia rheumatica
others: drugs, PE, IBD
examples of intermittent fevers
malaria septicaemia UTI PID TB
investigation of common STIs
detailed examination of genitalia urine dipstick and MC+S ulcers: swab for HSV urethral smear: gonorrhoea urethral swab: chlamydia blood tests: syphilis, hepatitis, HIV
about chlamydia
most prevalent STI in the UK
approx 1 in 10 young women in the UK have chlamydia
incubation period 7-21 days
asymptomatic in around 70% of women dn 50% of men
women - cervicitis, dysuria
men - urethral discharge, dysuria
complications of chlamydia
epididymitis
PID
endometritis
infertility
management of chlamydia
doxycycline (7d) or azithromycin (single dose)
if pregnant, azithromycin, erythromycin or amoxicillin may be used
about gonorrhoea
gram negative diplococcus neisseria gonorrhoea
incubation period is 2-5d
males: urethral discharge, dysuria
females: cervicitis e.g. leading to vaginal discharge
potential complications of gonorrhoea
urethral strictures
epididymitis
salpingitis (therefore infertility)
DIC
management of gonorrhoea
cephalosporins - ceftriaxone 500mg IM as a single dose
about syphilis
characterised by primary, secondary and tertiary stages
primary: painless ulcer at site of sexual contact, local non-tender lymphadenopathy
secondary: (6-10w) fevers, lymphadenopathy, rash on trunk, palms and soles
tertiary: granulomatous lesions of the skin and bones, ascending aortic aneurysms, general paralysis of the insane
incubation period 9-90days
management of syphilis
benzylpenicillin
about herpes simplex
primary infection may present with a severe gingivostomatitis
cold sores
painful genial ulceration
management of herpes simplex
oral aciclovir
genital warts
common cause of attendance at GUM clinics
HPV is the cause - type 16 and 18 predispose to cervical cancer
small fleshy protuberances which are slightly pigmented
managed with topical podophyllum or cryotherapy
about thrush
candida albicans
commonest cause of discharge
vulva and vagina may be red, fissured and sore
managed with clotrimazole pessary
bacterial vaginosis
causes a fishy smelling discharge
vagina is not inflamed
management: oral metronidazole for 5-7 days
70-80% initial cure rate
relapse rate of >50% within 3 months
what is PID
Pelvic inflammatory disease (PID) is a term used to describe infection and inflammation of the female pelvic organs including the uterus, fallopian tubes, ovaries and the surrounding peritoneum. It is usually the result of ascending infection from the endocervix
causative organisms of PID
Chlamydia trachomatis- the most common cause
Neisseria gonorrhoeae
Mycoplasma genitalium
Mycoplasma hominis
features of PID
Lower abdominal pain Fever Deep dyspareunia Dysuria and menstrual irregularities may occur Vaginal or cervical discharge Cervical excitation
management of PID
oral ofloxacin nd oral metronidazole
complications of PID
infertility
chronic pelvic pain
ectopic pregnancy
life threatening complications of malaria
AKI hypoglycaemia (esp pregnant women) severe anaemia DIC septicaemia seizures or other CNS complications
risk factors for typhoid fever
overcrowded living in endemic areas e.g. india
poor sanitation/untreated water in endemic areas
poor personal hygiene in endemic areas
symptoms of typhoid fever
HIGH FEVER (sometimes stepwise fashion with 5-7d of daily increments) dull frontal headache abdominal pain anorexia apathic-lethargic state constipation cough diarrhoea malaise
rouse spots- abdomen, chest, blanching erythematous maculopapular lesions
risk factors for UTI
sexual activity spermicide use post menopause positive family history history of recurrent UTI presence of a foreign body
organisms in UTI
E coli in 70-95% of uncomplicated cases
staph aureus in 5-20% of cases
broad range of bacteria can cause complicated UTIs, and many are resistant to antimicrobial agents
ascending pathway of UTI colonisation
The most common route of infection in females is via an ascending pathway. Colonisation of the vagina may occur first, then ascends into the urinary tract. Ascending UTI is amplified by factors that promote the introduction of bacteria at the urethral meatus and by iatrogenic means. Stasis of bladder urine impairs the defence against infection provided by bladder emptying.
investigations of UTI
urine dipstick
urine microscopy
urine culture and sensitivity
abacteriuric frequency or dysuria (‘urethral syndrome’)
Causes of truly abacteriuric dysuria include postcoital bladder trauma, vaginitis, atrophic vaginitis or urethritis in the elderly, and interstitial cystitis. In symptomatic young women with ‘sterile pyuria’, Chlamydia infection and tuberculosis must be excluded.
what diseases does herpes simplex virus cause?
cold sores
painful genital ulveration
severe gingicostomatitis
what diseases does herpes zoster (shingles) cause?
acute, unilateral, painful blistering rash caused by reactivation of the varicella zoster virus
what does herpes simplex keratitis cause?
presents with a dendritic corneal ulcer - red and painful eye
infectious mononucleosis
Infectious mononucleosis (glandular fever) is caused by EBV in 90% of cases. The classic triad is seen in around 98% of patients:
Sore throat
Lymphadenopathy (May present in the anterior and posterior triangles of neck)
Pyrexia
Other features include:
Malaise, anorexia, headache
Splenomegaly
Lymphocytosis
meningitis signs and symptoms
Meningitis is inflammation of the meninges usually caused by bacterial, viral or fungal infection.
Headache Nausea or vomiting Neck stiffness Fever Photophobia Confusion and seizures
diagnosis and management of meningitis
Diagnosis:
LP
Blood culture in patients where LP is delayed
Management
All patients should be transferred to hospital urgently
Patients in pre-hospital setting (e.g. GP) IM Benzylpenicillin
Hospital Ceftriaxone + Aciclovir
what is encephalitis?
Encephalitis is defined as inflammation of the brain parenchyma associated with neurological dysfunction such as altered state of consciousness, seizures, personality changes, cranial nerve palsies and speech problems. It is the result off direct inflammation of the brain tissue, as opposed to the inflammation of the meninges, and can be the result of infectious or non-infectious causes
signs and symptoms of encephalitis
Fever Seen in infectious causes
Rash E.g. Vesicular eruption in HSV, erythema nodosum in TB
Altered mental state
Focal neurological deficit E.g. aphasia, hemiparesis, ataxia
diagnosis and treatment of meningitis
Diagnosis:
LP
Bloods FBC, U+E’s, LFTs, blood cultures
Imaging CXR, CT brain
Treatment depends on the underlying cause
cerebral abscess
CNS abscesses may result from a number of causes including, extension of sepsis from middle ear or sinuses, trauma or surgery to the scalp, penetrating head injuries and embolic events from endocarditis.
signs and symptoms of cerebral abscess
The presenting symptoms will depend upon the site of the abscess (those in critical areas e.g.motor cortex) will present earlier. Abscesses have a considerable mass effect in the brain and raised intra cranial pressure is common.
Although fever, headache and focal neurology are highly suggestive of a brain abscess the absence of one or more of these does not exclude the diagnosis, fever may be absent and even if present, is usually not the swinging pyrexia seen with abscesses at other sites
diagnosis and management of cerebral absess
Diagnosis
• Assessment of the patient includes imaging with CT scanning
Management
• Treatment is usually surgical; a craniotomy is performed and the abscess cavity debrided. The abscess may reform because the head is closed following abscess drainage
causes of meningitis
0-3 months
o Group B streptococcus
o E.Coli
o Listeria monocytogenes
3months – 6 years
o Neisseria meningitidis
o Streptococcus pneumoniae
o Haemophilus influenza
6 years – 60 years
o Neisseria meningitidis
o Streptococcus pneumonia
Immunosuppressed
o Listeria monoctogenes
CSF in bacterial meningitis
cloudy
low glucose (<1/2 plasma)
high protein (>1g/l)
10-5000 polymorphs (white cells)
CSF in viral meningitis
clear/cloudy
60-80% plasma glucose
normal/raised protein
15-1000 lymphocytes (white cells)
CSF in TB meningitis
slightly cloudy, fibrin web
low glucose (<1/2 plasma)
high protein (>1g/l)
10-1000 lymphocytes (white cells)
indications of LP
suspicion of meningitis
suspicion of SAH
suspicion of CNS diseases such as GBS
complications of LP
coning
introduction of infection into the CSF
contraindications of LP
local skin sepsis
bleeding diathesis e.g. anticoagulant therapy
signs of spinal cord compression
papilloedema or other signs of raised ICP
suspicion of intracranial or cord mass
congenital neurological lesions in lumbosacral region
contraindications for LP in children/young people with suspected meningitis or meningococcal disease
• Signs suggesting raised ICP, reduced or fluctuating level of consciousness (GCS less than 9 or a drop of 3 or more)
o Relative bradycardia and hypertension
o Focal neurological signs
o Abnormal posture or posturing
o Unequal, dilated or poorly responsive pupils
o Papilloedema
• Shock
• Extensive or spreading purpura
• After convulsions until stabilised
• Coagulation abnormalities
o Coagulation results outside the normal range
o Platelet count below 100 x 109/litre
o Receiving anticoagulant therapy
• Local superficial infection at the LP site
