Ed's microbiology Flashcards
What is the appropriate antibiotic for low severity (CURB65 score 0-1) CAP?
- doxycycline
- alternatives: amoxicillin or clarithryomycin
What is the appropriate antibiotic for mod/severe (CURB65 score 2-5) CAP?
- benzyl penicillin IV and
- doxycycline PO
What is the appropriate antibiotic management for infective exacerbation of COPD?
- doxycline
- alternative: clarithromycin or amoxicillin
What is the antibiotic management for uncomplicated UTI?
- nitrofurantoin
- women = 3 days, men = 7 days
What is the appropriate antibiotic management for non-severe tissue infection?
- flucloxacillin PO
What is the appropriate antibiotic management for severe soft tissue infection?
- flucloxacillin IV
Broad-spectrum antibiotics suppress the normal gut flora. Which bacteria does this allow to develop and how does it cause damage?
- Clostridium difficile
- gram-positive rod
- produces exotoxin -> causes intestinal damage
- leading to syndrome called pseudomembranous colitis
What is now the leading cause of C. Diff infection?
- second + third generation cephalosporins
- eg. ceftriaxone, cefotaxime, cefoxitin
How is diagnosis of C. Diff infection made?
- Stool sample detecting toxin
What is the management of C. Diff infection?
- oral metronidazole
- 10-14 days
Describe the rash often associated with meningococcal septicaemia/meningitis
- petechial or purpuric rash is typically associated w/ meningococcal meningitis
- a rash is noted in 80% to 90% of patients
- most commonly 4-18 hours after initial symptoms of illness
- typically, rash is non-blanching petechial or purpuric
- but a few patients may initially have non-specific erythematous macular rash
What is the immediate management of the septic patient?
SEPSIS 6 - GIVE 3, TAKE 3
- administer oxygen -> aim sats >94%
- take blood cultures
- give broad spectrum antibiotics -> co-amoxiclav IV + amikacin IV
- give IV fluid challenges
- measure serum lactate
- measure accurate hourly urine output
What is the definition of pyrexia of unknown origin (PUO)?
- a temperature >38.3 for >3weeks
- with no obvious source
- despite appropriate investigations
What are infectious causes of PUO?
- abscesses (lung, liver, pelvic)
- empyema
- rheumatic fever
- tuberculosis
- parasites (malaria)
- fungi
- septicaemia
What are neoplasmic causes of PUO?
- lymphomas
What connective tissue disorders might cause PUO?
- rheumatoid arthritis
- polymyalgia rheumatica
What are other (not infections, neoplasms or connective tissue disorders) causes of PUO?
- drugs
- PE
- IBD
What investigations would you like to do for common STIs?
- detailed examination of genitalia
- urine dipstick and MC+S
- ulcers -> swab for HSV
- urethral smear -> gonorrhoea
- urethral swab -> chlamydia
- blood tests -> syphillis, hepatitis + HIV
What is the most prevalent sexually transmitted infection in the UK?
- chlamydia
- approx 1 in 10 young women in UK have it
- incubation period = 7-21 days
What are features of chlamydia?
- asymptomatic in around 70% of women + 50% of men
- women: cervicitis (discharge, bleeding), dysuria
- men: urethral discharge, dysuria
The investigation of choice for chlamydia is a urethral swab. What are potential complications of chlamydia?
- epididimytis
- PID
- endometritis
- infertility
What is the management of chlamydia?
- doxycycline (7days)
- or azithromycin (single dose)
- if pregnant -> azithromycin, erythromycin or amoxicillin
What are features of the gonorrhoea bacterium?
- neisseria gonorrhoea
- gram negative diplococcus
- incubation period = 2-5 days
What are clinical features of gonorrhoea?
- males -> urethral discharge, dysuria
- females -> cervicitis eg. leading to vaginal discharge
What are potential complications of gonorrhoea?
- urethral strictures
- epididimytis
- salpingitis (-> infertility)
- DIC
What is the management of gonorrhoea?
- cephalosporins -> ceftriaxone (500mg IM single dose)
Syphillis is an STI that is characterised by primary, secondary and tertiary stages. What are these stages?
- primary -> painless ulcer at site of sexual contact, local non-tender lymphadenopathy
- secondary (6-10wks after primary infection) -> fevers, lymphadenopathy, rash on trunk, palm + soles
- tertiary -> granulomatous lesions of skin + bones, ascending aortic aneurysms, ‘general paralysis of the insane’
What is the incubation period for syphillis?
- 9-90 days
What is the antibiotic management of syphillis?
- benzylpenicillin
How might Herpes Simplex present clinically?
- primary infection may present w/ severe gingivostomatitis (inflammation of oral mucosa)
- cold sores
- painful genital ulceration
What is the antibiotic management of herpes simplex?
for both gingivostomatitis and genital herpes:
- oral aciclovir
A common cause of attendance at GUM clinic would be genital warts. What are these caused by?
- caused by many varieties of HPV
- type 16 and 18 predisposes to cervical cancer
What do genital warts look like?
- small fleshy protuberances which are slightly pigmented
What is the management of genital warts?
- topical podophyllum or cyrotherapy
How does thrush (candida albicans) present?
- commonest cause of discharge
- classically described as white curds
- vulva + vagina may be red, fissured + sore
What is the management of thrush?
- clotrimazole pessary
How does bacterial vaginosis present clinically?
- causes fishy smelling discharge
- vagina is not inflammed
What is the antibiotic management of bacterial vaginosis?
- oral metronidazole (5-7 days)
- 70-80% initial cure rate
- relapse rate >50% within 3 months
What is pelvic inflammatory disease (PID)?
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
What are causative organisms for PID?
- chlamydia trachomatis - most common cause
- neisseria gonorrhoea
- mycoplasma genitalium
- mycoplasma hominis
What are clinical features of PID?
- lower abdo pain
- fever
- deep dyspareunia
- dysuria + menstrual irregularities may occur
- vaginal or cervical discharge
- cervical excitation
What is the investigation for PID?
- screen for chlamydia and gonorrhoea
What is the antibiotic management of PID?
- oral ofloxacin
- oral metronidazole
What are complications of PID?
- infertility
- chronic pelvic pain
- ectopic pregnancy
What are the life-threatening complications of malaria?
- AKI - usually due to dehydration + hypovolaemia, can also be due to acute tubular necrosis in severe disease
- hypoglycaemia - common w/ severe disease + may be worsened by quinine therapy, preg women are most at risk
- severe anaemia - most common in young children due to direct red cell lysis
- DIC - bleeding gums, epistaxis + petechiae in severe disease
- septicaemia
- seizure or other CNS complications
What are risk factors for typhoid fever?
- overcrowded living in endemic areas (eg. india)
- poor sanitation/untreated water in endemic areas
- poor personal hygeine in endemic areas
What are symptoms and signs of typhoid fever?
- HIGH FEVER -> sometimes occurs in a stepwise fashion with 5-7 days of daily increments in max temp of 0.5 to 1 celcius
- dull frontal headache
- abdominal pain
- anorexia
- apathetic-lethargic state
- constipation
- cough
- diarrhoea
- malaise
Signs include rose spots (blanching erythematous maculopapular lesions) reported in 5-30% of cases; usually occurs on abdo + chest
What are the 3 types of UTI?
- infecious cystitis is the most common UTI, caused by bacterial infection of bladder
- pyelonephritis is an infection of kidney often occurs via bacterial ascent
- urethritis is an infection causing inflammation of the urethra
What are risk factors for UTI?
- sexual activity
- spermicide use
- post-menopause (absence of oestrogen)
- positive FHx
- history of recurrent UTI
- presence of a foreign body
What organisms cause UTI?
- E. Coli is the cause in 70-95% of uncomplicated cases
- Staph saprophyticus is cause in 5-20% of cases
- broad range of bacteria cause complicated UTIs, many are resistant to multiple antimicrobial agents
What are the clinical features of UTI, specifically for cystitis?
- frequency of micturition by day and night
- painful voiding (dysuria)
- suprapubic pain + tenderness
- haematuria
- smelly urine
these symptoms relate to bladder + urethral inflammation, commonly called ‘cystitis’ + suggest lower urinary tract infection
Which symptoms would suggest extension of the infection to the pelvis and kidney, ie. pyelonephritis?
- loin pain + tenderness
- fever
- systemic upset
In whom is it important to always bear in mind the possibility of UTI and why?
- in small children
- cannot complain of dysuria
- symptoms often ‘atypical’
- possibility of UTI must always be considered in the freful, febrile child who fails to thrive
Which investigations are important for UTI?
- urine dipstick -> most effective in UTI w/ high bacterial count, diagnosis better if used in combo with other tests. Results = nitrite + leukocyte esterase positive
- urine microscopy -> used to confirm organism type + guide antibiotic selection in complicated UTI or pyelonephritis. Result = bacteria, WBC, possibly RBC
- urine culture + sensitivity -> most specific and sensitive test. Result = growth of >105 CFU/mL
What is the management of uncomplicated UTI (where there is normal renal tract + function)? How long is this for?
- nitrofurantoin 50mg PO 6hourly
- women -> 3 days
- men -> 7 days
- alternatives: 3day course of trimethoprim/sulfamethoxazole
What is the management of complicated UTI (abnormal renal/GU tract, voiding problems, virulent organism) and/or pyelonephritis?
- co-amoxiclav IV 1.2g, 8hrly
- then oral when afebrile
- complete 7-day course
Abacteriuric frequency or dysuria can be termed ‘urethral syndrome’. What are causes of abacteriuric dysuria?
- postcoital bladder trauma
- vaginitis
- atrophic vaginitis
- urethritis (in elderly)
- interstitial cystitis
In symptomatic young women w/ ‘sterile pyuria’, chlamydia infection and tuberculosis must be excluded.
What are the 3 clinical manifestations of herpes simplex virus?
- cold sores
- painful genital ulceration
- severe gingivostomatitis
How does herpes zoster manfiest clinically?
- AKA shingles
- acute, unilateral painful blistering rash
- caused by reactivation of Varicella Zoster virus
How does herpes simplex keratitis present?
- presents w/ a dendritic corneal ulcer
- leads to red and painful eye
Infectious mononucleosis (glandular fever) is caused by EBV in 90% of cases. A classic triad of symptoms is seen in around 98% of patients. What is the triad?
- sore throat
- lymphadenopathy -> may present in anterior + posterior triangles of neck
- pyrexia
Other features include malaise, anorexia, headache, splenomegaly and lymphocytosis
Meningitis is the inflammation of the meninges usually caused by bacterial, viral or fungal infection. What are the signs and symptoms for this?
- headache
- nausea or vomiting
- neck stiffness
- fever
- photophobia
- confusion + seizures
How do you diagnose meningitis?
- lumbar puncture
- blood culture in patients where LP is delayed
What is the management of meningitis?
All patients should be transferred to hospital urgently
- patients in pre-hospital setting (eg GP) -> IM benzylpenicillin
- hospital -> ceftriaxone + aciclovir
What is encephalitis?
- inflammation of the brain parenchyma
- associated w/ neurological dysfunction eg. altered state of consciousness, seizures, personality changes, cranial nerve palsies + speech problems
- it is the result of direct inflammation of the brain tissue
- as opposed to inflammation of the meninges
- can be the result of infectious or non-infectious causes
What are signs and symptoms of encephalitis?
- fever -> seen in infectious causes
- rash -> eg. vesicular eruption in HSV, erythema nodosum in TB
- altered mental state
- focal neurological deficit -> eg. aphasia, hemiparesis, ataxia
How is diagnosis of encephalitis made?
- lumbar puncture
- bloods -> FBC, U+Es, LFTs, blood cultures
- imaging -> CXR, CT brain
The treatment depends on the underlying cause
What might cause CNS/cerebral abscesses?
- extension of sepsis from middle ear or sinuses
- trauma or surgery to scalp
- penetrating head injuries
- embolic events from endocarditis
What are the signs + symptoms of a cerebral abscess?
- presenting symptoms will depend upon site of abscess (those in critical areas eg. motor cortex will present earlier)
- abscesses have a considerable mass effect in brain + raised ICP is common
- although fever, headache + focal neurology are highly suggestive of a brain abscess, in the absence of 1+ of these does not exclude diagnosis
- fever may be absent and even if present, is usually not the swinging pyrexia seen with abscesses at other sites
How is diagnosis of cerebral abscess made?
- assessment of patient includes imaging with CT scanning
What is the management of a cerebral abscess?
- treatment usually surgical
- a craniotomy performed + abscess cavity debrided
- the abscess may reform bc the head is closed following abscess drainage
Which organisms are likely to cause meningitis in 6-60 year olds?
- neisseria meningitidis
- streptococcus pneumonia
What changes in the CSF would suggest a diagnosis of viral, bacterial and TB meningitis?
What are the indications for a lumbar puncture?
- suspicion of meningitis
- suspicion of subarachnoid haemorrhage (SAH)
- suspicion of CNS diseases such as Guillain-Barre syndrome
What are the possible complications of LP?
- coning
- introduction of infection into CSF
What are the contraindications for lumbar puncture?
- local skin sepsis
- bleeding diatheses eg. 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
- coagulation abnormalities
- after convulsions until stabilised
