Medical Microbiology

Question 1

CAP antibiotic treatment

Answer 1

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)

Question 2

COPD infective exacerbation antibiotic treatment

Answer 2

doxycycline PO 200mg STAT then 100mg OD (5-7 days)

Question 3

Uncomplicated UTI antibiotic treatment

Answer 3

Nitrofurantoin 50mg PO 6 hourly

Males: 7 days
Females: 3 days

Question 4

Soft tissue infection antibiotic treatment

Answer 4

Non-severe: flucloxacillin PO 500mg 6hrly (7 days)

Severe: flucloxicillin IV 2mg 6 hrly (review IV after 5-7 days depending on response)

Question 5

What is the effect of antibiotics on the gut and skin flora

Answer 5

broad spectrum abx suppress the normal gut flora

this allowed C Diff to develop

Question 6

what is c diff

Answer 6

gram positive rod that produces an exotoxin which causes intestinal damage leading to PSEUDOMEMBRANOUS COLITIS

Question 7

what is the leading cause of c diff

Answer 7

second and third generation cephalosporins

ceftriaxone, cefotaxima, cefoxitin

Question 8

what is the diagnosis of c diff?

Answer 8

stool sample detecting the toxin

Question 9

treatment of c diff

Answer 9

oral metronidazole for 10-14 days

Question 10

meningococcal septicaemia/meningitis rash

Answer 10

petechial or purpuric rash
80-90% of patients
most commonly 4 to 18 hours after initial symptoms of illness

typically non-blanching

Question 11

sepsis six

Answer 11

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

Question 12

what is pyrexia of unknown origin (PUO)

Answer 12

a temperature over 38.3 for >3 weeks with no obvious source despite appropriate investigations

Question 13

what are possible causes of PUO?

Answer 13

infections: abscesses, empyema, RF, TV, parasites, fungi
neoplasms: lymphomas

CT disease: RA, polymyalgia rheumatica

others: drugs, PE, IBD

Question 14

examples of intermittent fevers

Answer 14

malaria
septicaemia
UTI
PID
TB

Question 15

investigation of common STIs

Answer 15

detailed examination of genitalia
urine dipstick and MC+S
ulcers: swab for HSV
urethral smear: gonorrhoea
urethral swab: chlamydia
blood tests: syphilis, hepatitis, HIV

Question 16

about chlamydia

Answer 16

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

Question 17

complications of chlamydia

Answer 17

epididymitis
PID
endometritis
infertility

Question 18

management of chlamydia

Answer 18

doxycycline (7d) or azithromycin (single dose)

if pregnant, azithromycin, erythromycin or amoxicillin may be used

Question 19

about gonorrhoea

Answer 19

gram negative diplococcus neisseria gonorrhoea
incubation period is 2-5d

males: urethral discharge, dysuria
females: cervicitis e.g. leading to vaginal discharge

Question 20

potential complications of gonorrhoea

Answer 20

urethral strictures
epididymitis
salpingitis (therefore infertility)
DIC

Question 21

management of gonorrhoea

Answer 21

cephalosporins - ceftriaxone 500mg IM as a single dose

Question 22

about syphilis

Answer 22

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

Question 23

management of syphilis

Answer 23

benzylpenicillin

Question 24

about herpes simplex

Answer 24

primary infection may present with a severe gingivostomatitis

cold sores

painful genial ulceration

Question 25

management of herpes simplex

Answer 25

oral aciclovir

Question 26

genital warts

Answer 26

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

Question 27

about thrush

Answer 27

candida albicans commonest cause of discharge vulva and vagina may be red, fissured and sore managed with clotrimazole pessary

Question 28

bacterial vaginosis

Answer 28

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

Question 29

what is PID

Answer 29

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

Question 30

causative organisms of PID

Answer 30

Chlamydia trachomatis - the most common cause Neisseria gonorrhoeae Mycoplasma genitalium Mycoplasma hominis

Question 31

features of PID

Answer 31

``` Lower abdominal pain Fever Deep dyspareunia Dysuria and menstrual irregularities may occur Vaginal or cervical discharge Cervical excitation ```

Question 32

management of PID

Answer 32

oral ofloxacin nd oral metronidazole

Question 33

complications of PID

Answer 33

infertility chronic pelvic pain ectopic pregnancy

Question 34

life threatening complications of malaria

Answer 34

``` AKI hypoglycaemia (esp pregnant women) severe anaemia DIC septicaemia seizures or other CNS complications ```

Question 35

risk factors for typhoid fever

Answer 35

overcrowded living in endemic areas e.g. india poor sanitation/untreated water in endemic areas poor personal hygiene in endemic areas

Question 36

symptoms of typhoid fever

Answer 36

``` 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

Question 37

risk factors for UTI

Answer 37

``` sexual activity spermicide use post menopause positive family history history of recurrent UTI presence of a foreign body ```

Question 38

organisms in UTI

Answer 38

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

Question 39

ascending pathway of UTI colonisation

Answer 39

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.

Question 40

investigations of UTI

Answer 40

urine dipstick urine microscopy urine culture and sensitivity

Question 41

abacteriuric frequency or dysuria ('urethral syndrome')

Answer 41

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.

Question 42

what diseases does herpes simplex virus cause?

Answer 42

cold sores painful genital ulveration severe gingicostomatitis

Question 43

what diseases does herpes zoster (shingles) cause?

Answer 43

acute, unilateral, painful blistering rash caused by reactivation of the varicella zoster virus

Question 44

what does herpes simplex keratitis cause?

Answer 44

presents with a dendritic corneal ulcer - red and painful eye

Question 45

infectious mononucleosis

Answer 45

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

Question 46

meningitis signs and symptoms

Answer 46

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 ```

Question 47

diagnosis and management of meningitis

Answer 47

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

Question 48

what is encephalitis?

Answer 48

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

Question 49

signs and symptoms of encephalitis

Answer 49

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

Question 50

diagnosis and treatment of meningitis

Answer 50

Diagnosis: LP Bloods FBC, U+E’s, LFTs, blood cultures Imaging CXR, CT brain Treatment depends on the underlying cause

Question 51

cerebral abscess

Answer 51

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.

Question 52

signs and symptoms of cerebral abscess

Answer 52

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

Question 53

diagnosis and management of cerebral absess

Answer 53

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

Question 54

causes of meningitis

Answer 54

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

Question 55

CSF in bacterial meningitis

Answer 55

cloudy low glucose (<1/2 plasma) high protein (>1g/l) 10-5000 polymorphs (white cells)

Question 56

CSF in viral meningitis

Answer 56

clear/cloudy 60-80% plasma glucose normal/raised protein 15-1000 lymphocytes (white cells)

Question 57

CSF in TB meningitis

Answer 57

slightly cloudy, fibrin web low glucose (<1/2 plasma) high protein (>1g/l) 10-1000 lymphocytes (white cells)

Question 58

indications of LP

Answer 58

suspicion of meningitis suspicion of SAH suspicion of CNS diseases such as GBS

Question 59

complications of LP

Answer 59

coning | introduction of infection into the CSF

Question 60

contraindications of LP

Answer 60

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

Question 61

contraindications for LP in children/young people with suspected meningitis or meningococcal disease

Answer 61

• 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