Infection & Antibiotic Prescribing Flashcards
Cellulitis - common organisms and antibiotics
Group A streptococcus eg. S. pyogenes, Stapholococcus aureus. Less commonly - Strep pneumoniae, Haemophilus influenza, Pseudomonas auriguinosa
Flucloxicillan
Clarithromycin or Clindamycin if pen allergic.
Common cold
Rhinovirus
Most common cause of community acquired pneumonia
Streptococcus pneumoniae
Staph aureus common cause pneumonia after having had influenza
Most common cause bronchiectasis exacerbation
Haemophilus influenza
Pseudomonas auruginosa
Moraxella catarrhalis
Empirical treatment regimes for community acquired pneumonia
Low severity, CURB 0-1: amoxicillin or if pen allergic - doxycycline or clarithromycin
Moderate severity, CURB 2: amoxicillin plus clarithromycin or if pen allergic - doxycycline
Severe severity, CURB 3-5: Co-amoxiclav IV plus clarithromyci IV or Cefuroxime plus clarithromycin IV
Most common cause erysipelas and treatment
Streptococcus pyogenes (also known as beta-hemolytic group A streptococci).
Flucloxicillan or Erythromycin
Antibiotic contraindicated in prolonged QT
Erythromycin
N.b. normal corrected QT interval is less than 430 ms in males and 450 ms in females
Antibiotic for invasive diarrhoea (bloody and fever)
Ciprofloxacin
Abx for traveller’s diarrhoea and non-invasive diarrhoeal illnesses when treatment is necessary
Clarithromycin
Organism responsible for scabies? Treatment?
Mite - Sarcoptes scabiei
Delayed type IV hypersensitivity reaction –> pruritus
Treatment -
permethrin 5% is first-line
malathion 0.5% is second-line
give appropriate guidance on contact, laundry etc
pruritus persists for up to 4-6 weeks post eradication
Organism and treatment for pityriasis versicolor?
Malassezia furfur (formerly termed Pityrosporum ovale)
Topical anti-fungal or ketonazole shampoo
Helicobacter pylori treatment
Omeprazole, amoxicillin, metronidazole
Following a splenectomy patients are particularly at risk from what organisms?
Pneumococcus, Haemophilus, meningococcus and Capnocytophaga canimorsus*(from dog bites) infections
Prophylactic abx: eg penicillin often given - but doesn’t prevent Haemophilus bacause of the beta lactamases
Vaccinations: if elective, should be done 2 weeks prior to operation
Hib, meningitis A & C
annual influenza vaccination
pneumococcal vaccine every 5 years
Seborrhoeic dermatitis - organism and treatment
Chronic dermatitis thought to be caused by an inflammatory reaction related to a proliferation of a normal skin inhabitant, a fungus called Malassezia furfur (formerly known as Pityrosporum ovale).
Special shampoo for scalp (head and shoulders) and topical antifungal eg ketoconazole, sometimes topical steroid
Presentation and bacteria most likely responsible in meningococcal meningitis/ septacaemia
Petechiae/ purpura/ septicaemic rash
Meningococcus/Neisseria meningitidis
Cough in a child with white cell count 32 ×109/L, 90% lymphocytes.
Pertussis (Whooping cough)
Cough associated with a raised white cell count and neutrophilia
Pneumococcal pneumonia
Pseudomonas aeruginosa isolated from sputum is likely in what condition?
Cystic fibrosis - Staphylococcus aureus predominate but with repeated courses of antibiotic therapy subsequent infections with multiple antibiotic resistant organisms develop. These latter organisms include Pseudomonas aeruginosa, often ‘mucoid’ strains.
Adults with bronchiectasis can often have similar infections
Benzyl penicillin - how is it administered and give examples of indications
Benzyl penicillin (penicillin G) is inactivated by gastric acid and so must be given parenterally (unlike penicillin V).
It is an effective treatment for Strep. infections, for example, cellulitis, and is also effective for tetanus.
Common organisms infective endocarditis
Historically Streptococcus viridans was the most common cause of infective endocarditis. This is no longer the case, except in developing countries. Staphylococcus aureus is now the most common cause of infective endocarditis
What organism commonly colonizes indwelling lines and are the most cause of endocarditis in patients following prosthetic valve surgery? How long is it before this returns to normal?
Coagulase-negative Staphylococci such as Staphylococcus epidermidis
Usually the result of perioperative contamination. After 2 months the spectrum of organisms which cause endocarditis return to normal (i.e. Staphylococcus aureus is the most common cause)
Where is Streptococcus bovis commonly found and associated with?
Bowel - Colon cancer
What vaccinations must be avoided in immunosupressed individuals?
Live attenuated vaccines: BCG MMR oral polio yellow fever oral typhoid
Presentation, responsible organism and treatment of whipples disease
Whipple’s disease is a rare multi-system disorder caused by Tropheryma whippelii infection. It is more common in those who are HLA-B27 positive and in middle-aged men
Features
malabsorption: diarrhoea, weight loss
large-joint arthralgia
lymphadenopathy
skin: hyperpigmentation and photosensitivity
pleurisy, pericarditis
neurological symptoms (rare): ophthalmoplegia, dementia, seizures, ataxia, myoclonus
Investigation
jejunal biopsy shows deposition of macrophages containing Periodic acid-Schiff (PAS) granules
Management
guidelines vary: oral co-trimoxazole for a year is thought to have the lowest relapse rate, sometimes preceded by a course of IV penicillin
Most common meningitis causing organism, by age?
0 - 3 months
Group B Streptococcus (most common cause in neonates)
E. coli
Listeria monocytogenes
3 months - 6 years
Neisseria meningitidis
Streptococcus pneumoniae
Haemophilus influenzae
6 years - 60 years
Neisseria meningitidis
Streptococcus pneumoniae
> 60 years
Streptococcus pneumoniae
Neisseria meningitidis
Listeria monocytogenes
Immunosuppressed
Listeria monocytogenes
Osteomyelitis - most common organism and treatment?
Staph. aureus - except in patients with sickle-cell anaemia: Salmonella.
flucloxacillin for 6 weeks
clindamycin if penicillin-allergic
Antibiotics known to cause cholestasis
Co-amoxiclav, flucloxicillin, Erythromycin
Organism most common in dog bites? And treatment?
Pasteurella multocida.
Co-amoxiclav OR
if penicillin-allergic then doxycycline + metronidazole
Most common side effect of gentamicin
nephrotoxicity: accumulates in renal failure, lower doses and more frequent monitoring is required
(As well as ototoxicity: irreversible, due to auditory or vestibular nerve damage)
What is the likely diagnosis of someone who develops a maculopapular, pruritic rash following amoxicillin for a URTI?
Infectious mononucleosis (glandular fever) is caused by the Epstein-Barr virus (also known as human herpesvirus 4, HHV-4). It is most common in adolescents and young adults.
Features
sore throat
lymphadenopathy
pyrexia
malaise, anorexia, headache
palatal petechiae
splenomegaly - occurs in around 50% of patients and may rarely predispose to splenic rupture
hepatitis
presence of 50% lymphocytes with at least 10% atypical lymphocytes
haemolytic anaemia secondary to cold agglutins (IgM)
a maculopapular, pruritic rash develops in around 99% of patients who take ampicillin/amoxicillin whilst they have infectious mononucleosis
Diagnosis
heterophil antibody test (Monospot test) - NICE guidelines suggest FBC and Monospot in the second week of the illness to confirm a diagnosis of glandular fever.
Management is supportive and includes:
rest during the early stages, drink plenty of fluid, avoid alcohol
simple analgesia for any aches or pains
consensus guidance in the UK is to avoid playing contact sports for 8 weeks after having glandular fever to reduce the risk of splenic rupture
Hepatitis B serology - immune due to natural infection, immune due to hep B vaccine, acutely infected and chronically infected
anti-HBc, antiHBs = immune due to natural infection
anti-HBs = immune due to hepB vaccine
HBsAg, anti-HBc, IGM antiHBc = Acutely infected
HBsAg, anti-HBc = chronically infected
Accepted as the most common cause of infectious diarrhoea in children in the developed society.
Rotavirus
Can follow ingestion of dust containing dried faecal material.
Hepatitis A
Attaches the small intestinal border and releases exotoxin.
Escherichia coli
What is the most likely causative organism of peritoneal dialysis peritonitis?
Fifty per cent of episodes of PD peritonitis are caused by Gram positive organisms, and the most common organism is coagulase negative staph. contamination from skin flora.
Most common organism seen in acute exacerbations of COPD
Haemophilus inluenzae
Acute cholangitis - bacterial group and treatment
Anaerobes so metronidazole plus broad spectrum cephalosporins, ciprofloxacin, gentamicin are appropriate.
Hospital acquired pneumonia - common organisms
Bacterial: S. aureus(17.4%), Pseudomonas aeruginosa (17.4%), Klebsiella pneumoniae and Enterobacter spp. (18.1%)
Viral pneumonia: influenza and respiratory syncytial virus and, in the immunocompromised host, cytomegalovirus- cause 10-20% of infections.
Acute otitis media - common organisms and treatment
Viral, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis
Supportive - analgesia and benzocaine ear drops.
Antibiotics in bilateral acute otitis media < 2 years old, severe unilateral or bilateral over 2 - Amoxicillan, Co-amoxiclav
Otitis externa
Most common - Pseudomonas aeruginosa and Staphylococcus aureus. Candida albicans and Aspergillus species are the most common fungal pathogens.
Treat with ear drops containing antibiotics and corticosteroids eg Dexamethasone 0.1%, ciprofloxacin 0.3%, Hydrocortisone acetate 1%, gentamicin 0.3%
Antifungal solutions are used in the case of fungal infections eg Flumetasone pivalate 0.02%, clioquinol 1%
Septic arthritis - common offenders and treatment
Staph aureus, Streptococci, Haemophilus influenzae - previously most common in children, but less now due to vaccination, Neisseria gonorrhoeae, Escherichia coli
Flucloxacillin for 4-6 weeks (longer if infection complicated); if penicillin-allergic then use clindamycin instead.
If meticillin-resistant S. aureus (MRSA) is suspected, vancomycin (teicoplanin may also be used) for 4-6 weeks (longer if infection complicated)
If gonococcal arthritis or Gram-negative infection is suspected, cefotaxime (ceftriaxone may also be used). Treat Gram-negative infections for 4-6 weeks (longer if infection complicated). Treat gonococcal infection for two weeks.
Uncomplicated pyelonephritis -treatment
Oral ciprofloxacin for 7-10 days
Uncomplicated UTI - treatment
Trimethoprim or nitrofurantoin 3 days
seven days for the treatment of UTIs in me
Flare up/ infected eczema
14-day course of flucloxacillin
