BNF Chapter 5: Infections Flashcards
What are some examples of aminoglycoside antibiotics?
Gentamicin
Streptomycin
Amikacin
Neomycin
Tobramycin
Which aminoglycoside is the aminoglycoside of choice in the UK?
Gentamicin
Gentamicin
-Widely used for the treatment of serious infections
-Active against gram-positive and gram-negative organisms
-Broad spectrum but inactive against anaerobes and poor activity against haemolytic streptococci and pneumococci.
-When used to treat an undiagnosed serious infection, usually given alongside a penicillin or metronidazole (or both)
-Loading and maintenance doses calculated based on patient’s weight and _ function- treatment should not exceed 7 days.
Renal
What is the dosing of gentamicin based on?
Patient weight and renal function
When would Amikacin be used?
Treatment of serious infections caused by gentamicin-resistant gram-negative bacilli
Why is a once-daily dose of aminoglycoside preferred over multiple-daily doses?
More convenient, provides adequate serum concentrations.
When would a once-daily dose regimen of aminoglycoside antibiotics be contraindicated?
-Patients with endocarditis due to gram-positive bacteria
-HACEK endocarditis
-Burns of over 20% of total body area
-Creatinine clearance of less than 20mL/minute
-Pregnancy
Serum Concentrations
- Avoids both excessive and subtherapeutic concentrations
-Aminoglycosides have a narrow therapeutic index and are very harmful in toxicity
-Serum concentrations MUST be determined in the elderly, obese patients, cystic fibrosis patients, in renal impairment and if high doses are being given.
What three things must a clinician consider before selecting antibacterial therapy?
The patient
The known or likely causative organism
Risk of bacterial resistance
After how long should IV antibiotics be reviewed and stepped down to oral when possible?
48 hours
Sepsis- Early Management
- High risk patients suspected of sepsis should be given a broad spectrum antibacterial at the maximum recommended dose without delay (ideally within the first hour)
-Source of infection needs to be identified- then treat in-line with local guidance
-Need for IV fluids, inotropes, vasopressors and oxygen should also be assessed without day.
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What antibacterial should be given as prophylaxsis for secondary cases of Invasive group A streptococcal infections?
Phenoxymethylpenicillin
-Erythromycin or azithromycin if patients have a penicillin allergy
What antibacterial should be given for the prevention of secondary cases of Meningococcal meningitis?
Ciprofloxacin OR Rifampicin OR I/M Ceftriaxone
What is the first-line prophylaxis for the prevention of secondary disease related to Haemophilus Influenzae type b infection?
Rifampicin
What antibacterial should be given as prophylaxis for patients with pneumococcal infection when they have asplenia or sick-cell disease?
Phenoxymethylpenicillin
-Erythromycin if penicillin allergy
What should be used as antibacterial prophylaxis for gastro-intestinal operations on the stomach or oesophagus?
Single dose IV gentamicin or IV cefuroxime or IV co-amoxiclav - given up to 30 minutes before procedure
What prophylactic antibacterial should be given for a percutaneous endoscopic gastrostomy or jejunostomy?
Single dose of IV co-amoxiclav OR IV cefuroxime- up to 30 mins before procedure
What is the first-line treatment for Aspergillosis (a type of fungal infection)?
Voriconazole
What is the first-line antifungal for treating vaginal candidiasis?
Fluconazole by mouth
What antibiotics can be used first-line for community-acquired septicaemia?
A broad-spectrum antipseudomonal penicillin (e.g. piperacillin with tazobactam) OR a broad-spectrum cephalosporin (e.g. cefuroxime)
What antibiotics can be used for hospital-acquired septicaemia?
A broad-spectrum antipseudomonal beta-lactam antibacterial (e.g. piperacillin with tazobactam)
If an anaerobic infection is suspected for septicaemia, which antibiotic should be added to broad-spectrum cephalosporin?
Metronidazole
What are carbapenems?
Beta-lactam antibacterials with broad-spectrum of activity which includes many gram-positive and gram-negative bacteria.
What are Imipenem and Meropenem used to treat?
Severe and complicated infections, including hospital-acquired pneumonia, intra-abdominal infections, skin and soft tissue infections, and urinary tract infections
What are cephalosporins?
Broad-spectrum antibiotics which are used for the treatment of septicaemia, pneumonia, meningitis, biliary-tract infections, peritonitis and UTIs.
What is the main side-effect of cephalosporins?
Hypersensitivity
What are some examples of cephalosporins?
Cefalexin
Cefradine
Ceftriaxone
Threadworms
- All members of the family require treatment
-Mebendazole is first-line for treatment in patients over 6 months; single dose. Re-infection is very coomon, a second dose can be given after 2 weeks.
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Tapeworm Infections
-Niclosamide is used for tapeworm infections
-Side-effects include GI upset, lightheadesness and pruritis
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Herpes Simplex Infections
-HSV-1 is usually responsible for infections of the mouth, genital infection is usually due to HSV-1 or HSV-2.
-Topical antiviral treatment not generally recommended for oral herpes
-Treat primary or recurrent genital herpes with an antiviral drug.
Varicella-zoster Infections
-Chicken pox: self-limiting in healthy children, treatment is not recommended. Ibuprofen should be avoided due to the risk of skin reaction.
-Chicken pox is more severe in adolescents and adults- start antiviral tratment within 24 hours of onset.
Shingles- caused by the same virus. Offer oral antiviral treatment to immunocompromised patients, non-truncal involvement or those in severe pain. Start within 72 hours of rash onset.
-Offer to over 50s to reduce risk of post-herpetic neuralgia (chronic pain which persists after the rash has healed).
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What is human immunodeficiency virus (HIV)?
A retrovirus that causes immunodeficiency by infecting and destroying cells of the immune system, especially the CD4 cells. AIDs occurs when the number of CD4 cells falls below 200 cells/microlitre.
When does AIDS develop?
When the number of CD4 cells falls to below 200 cells/microlitre
What contributes to the greatest risk to mortality and morbidity due to HIV/AIDS?
Delayed HIV diagnosis and treatment
Aims of HIV Treatment
-Achieve an undetectable viral load
-Preserve immune function
-Reduce the mortality and morbidity associated with chronic HIV infection
-Reduce onward transmission of HIV
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HIV Treatment
-Initiate with two nucleoside reverse transcriptase inhibitors (NRTIs) as a backbone regimen plus one of the following: an integrase inhibitor (INI), a non-nucleoside reverse transcriptase inhibitor (NNRTI) OR a boosted protease inhibitor (PI).
-Backbone: emetricitabine + tenofovir OR disoproxil OR tenofovir alafenamide
-Third drug: atazanavir or darunavir.
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What is lyme disease?
A bacterial infection caused by Borrelia burgdorferi; transmitted to humans from the bite of an infected insect.
Lyme Disease
-Caused by the bite of an infected insect
-Characteristic rash- accompanied by malaise, fatigue, fever, swollen glands, neck pain, headache.
Treat with an antibacterial:
- Doxycycline is first-line
-Amoxicillin is an alternative if docycycline is unsuitable.
If there is CNS involvement, then ceftriaxone is first-line.
What are examples of macrolide antiobiotics?
Azithromycin
Erythromycin
Clarithromycin
Antibiotics and Food
-Nitrofurantoin- with or just after food
-Clarithromycin- with or just after
-Metronidazole- with or just after
-Ciprofloxacin- no milk two hours before or after
-Oxytetracycline- no milk two hours before or after
-Tetracycline- no milk two hours before or after
-Flucloxacillin- an hour before food, or two hours after
-Penicillin- an hour before food, or two hours after
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What are some examples of cephalosporin antibioitcs?
Cefalexin (most commonly used)
Cefazolin
Cefuroxime
Cefaclor
Ceftriaxone
Cefixime
Cefotaxime
Ceftazidime
What are the sub-categories of beta-lactam antibiotics?
Cephalosporins
Glycopeptides
Penicillins
Carbapenems
Monobactams
What drugs can be used first-line to treat TB?
Isoniazid
Rifampicin
Pyrazinamide
Ethambutol
Which antibiotics should be avoided in pregnancy?
Trimethoprim- teratogenic
Gentamicin- teratogenic
Tetracyclines- teeth discolouration
What antibiotics should be used to treat endocarditis?
Amoxicillin + low-dose gentamicin
What antibiotics can be used to treat chlamydia?
Azithromycin OR doxycycline
What is the standard first-line treatment for cellulitis?
Flucloxacillin
What is the antibiotic treatment for bacterial vaginosis?
Metronidazole
What are some examples of antibiotics that may discolour your urine?
Nitrofurantoin- yellow/brown
Metronidazole- dark
Rifampicin- yellow/orange/red/brown
How should ringworm be treated OTC?
Topical clotrimazole or terbinafine cream
Shingles
Refer if:
- Visual symptoms
-Unexplained red eye
-Immunocompromised
-Pain inadequately controlled by orsal analgesia
-Delayed healing
Oral antiviral within 72 hours of rash onset if any criteria met:
-Immunocompromised
-Non-truncal involvement
-Moderate/severe rash or pain
-Potentially in all over 50s to reduce likelihood of post-herpetic neuralgia.
In what patient groups should oral antiviral treatment be considered for the management of shingles?
-Immunocompromised
-Non-truncal involvement
-Moderate/severe rash or pain
-Potentially in all over 50s to reduce likelihood of post-herpetic neuralgia.
Advice for Shingles
-Avoid contact with people who have had not had chickenpox
-Avoid sharing clothes and towels
-Wear loose fitting clothing
-Avoid topical creams and dressings- irritation
-Keep rash clean and dry
Which antibiotic is first-line for cellulitis?
Flucloxacillin- take an hour before food, or two hours after. 500mg-1g QDS if orally, 1-2g QDS if IV
Clarithromycin (500mg BD 5-7 days), erythromycin or doxycycline if allergic
Which antibiotic can make you more sensitive to sunlight?
Doxycycline
_ is an antibiotic that can cause bone marrow suppression
Azithromycin
How does trimethoprim work?
By inhibiting bacterial DNA synthesis
What is the first-line antibiotic treatment for otitis externa?
Flucloxacillin
What is commonly prescribed for children with croup?
Oral corticosteroids, such as dexamethasone
Tendonitis is a potential side-effect from which group of antibioitics?
Fluoroquinolones (ciprofloxacin, levofloxacin etc)
Which antibiotics are most likely to lead to a C.diff infection?
Clindamycin
Cephalosporins (cefalexin, cefuroxime etc)
Penicillins
Fluoroquinolones (ciprofloxacin, ofloxacin etc)
What are some examples of fluoroquinolone antibiotics?
Ciprofloxacin
Ofloxacin
Moxifloxacin
What is the main indication for metronidazole?
Dental anaerobic infections
Clarithromycin is generally first-line for chest infections.
True or False?
True
_ is an antibiotic that can cause cholestatic jaundice or hepatitis as a side-effect.
Flucloxacillin
Penicillin-induced anaphylaxis is rare, but can be fatal. Cephalosporins are often used second-line, but there is cross-sensitivity- 7% of patients with a penicillin allergy will also be allergic to cephalosporins. ALWAYS worth a conversation with the prescriber.
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What infections is phenoxymethylpenicillin most indicated for?
Strep throat
Otitis media
Cellulitis
First gen. cephalosporins: cefalexin, cefixime, cefadroxil
Second gen.: Cefaclor
Third gen.: Cetotaxime
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Food and Antibiotics:
-Cephalosporins: ideally empty stomach EXCEPT cefuroxime
-Penicillin: ON AN EMPTY STOMACH
-Tetracyclines: ON AN EMPTY STOMACH
-Macrolides (azithromycin, clarithomycin, erythromycin etc): With or after food
-Quinolones (ciprofloxacin, levofloxacin etc): Ideally on an empty stomach
-Nitrofuranton: With food to aid absorption
-Clindamycin: Doesn’t matter
-Trimethoprim: Doesn’t matter
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How should a dose of an aminoglycoside antibiotic be calculated in an obese patient?
Use ideal body weight
What is clarithromycin most commonly prescribed for?
Stomach ulcers
Chest infections
Clindamycin: Patient must discontinue immediately and consult doctor if _ develops.
Diarrhoea
What can the use of systemic chloramphenicol cause?
Bone marrow suppression
Antituberculosis Drugs
-Cycloserine: need to monitor blood conc, especially in renal impairment
-Ethambutol
-Isoniazid- patient needs to be able to recognise signs of liver disorder, discontinue.
-Pyrazinamide
-Rifabutin
-Rifampicin- recognise symptoms of liver disorder, discontinue.
-Streptomycin- teratogenic
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Quinolones
-Ciprofloxacin
-Levofloxacin
-Moxifloacin
-Ofloxacin
All may impair performance of tasked skills, e.g. driving.
Can cause TENDON damage, although rare. Can also cause convulsions in patients with or without a history of seizures, NSAID use may also induce them.
Antifungals
Triazole: Fluconazole, Itraconazole, Voriconazole.
-Itraconazole: advise to recognise signs of liver disorder, discontinue
Imidazole: Ketoconazole, Miconazole
Polyene: Amphotericin, Nystatin
Echinocandin: Anidulafungin, Caspofungin, Micafungin
Other: Flucytosine, Griseofulvin, Terbinafine
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Which two groups of antibiotics are generally considered safest to use in pregnancy?
Penicillins
Cephalosporins
Which antibiotic is used to treat otitis externa?
Flucloxacillin
Which bacteria is a common cause of UTIs?
E.coli
Which antibiotic is injected in cases of suspected meningitis?
Benzylpenicillin IM
What are the main side-effects of tetracyclines?
Rash
Photosensitivity
Diarrhoea
In which situation may co-amoxiclav be used rather than amoxicillin?
If the infection is caused by resistant beta-lactamase bacteria
Which bacteria is the most common cause of a lower respiratory tract infection?
Streptococcus Pneumoniae
What is the first-line antibiotic for a C.difficile infection?
Vancomycin 125mg QDS for 10 days
Antibiotic Side-Effeccts
Tetracyclines:
-Photosensitivity
-_ hypertension
-_ discolouration
-Oesophageal irritation
-Visual disturbance
Quinolones:
-_ damage
-Seizures
-Psychiatric reactions
-_ prolongation
-Hypersensitivity/severe rash
Penicillin:
-Skin rash
Antibiotic-associated colitis
-Anaphylaxis
-Thrombocytopenia
-Vomiting
Macrolides:
-_ prolongation
-Antibiotic associated colitis
-Seizures
-Myasthenia gravis
-Pancreatitis
Cephalosporins:
-Hypersensitivity
-Diarrhoea
-Vulvovaginal candidiasis
-Vomiting
-Thrombocytopenia
Glycopeptides:
-Infusion reaction
-Red-man syndrome
-Nephrotoxicity
-Tinnitus
-Drug fever
Intracranial
Tooth
Tendon
QT
Which antibiotic is first-line for managing mastitis in breastfeeding?
Flucloxacillin
What are the three main symptoms of measles?
3C’s:
Cough, Conjunctivitis and cold symptoms
When would quinolones (ciprofloxacin, ofloxacin etc) be contraindicated?
In patients at risk of QT interval prolongation
Which antibiotics are most likely to cause C. difficile infections? What other drug too?
Second and third-generation cephalosporins, also clindamycin
PPIs
C.Difficile Infection Summary
-Symptoms include diarrhoea, abdominal pain, raised WBC count and a toxic megacolon if severe.
-Diagnosed by detecting C.Difficile in the stool.
Treatment of first-episode of infection:
-Vancomycin 125mg QDS for 10 days orally.
-Second line: Oral fidaxomicin
Third line: oral vancomycin +/- IV metronidazole
Recurrent Infection:
-Occurs in about 20% of patients, increases to 50% after second episode. If recurrent infection is within 12 weeks of symptom resolution, treat with oral fidaxomicin. If after 12 weeks, oral _ or fidaxomicin.
Vancomycin
How would recurrent C.difficile infections be managed?
If symptoms recur within 12 weeks of initial symptom resolution: oral fidaxomicin
If after 12 weeks: oral vancomycin or oral fidaxomicin
Which antibiotics can be used to treat an acute COPD exacerbation?
Amoxicillin OR
Tetracycline (doxycycline) OR
Clarithromycin
How would uncomplicated community-acquired pneumonia be treated?
Amoxicillin first-line
Doxycycline or clarithromycin in penicillin allergy
Which antibiotics would be used to treat hospital-acquired pneumonia?
Within 5 days of admission: co-amoxiclav or cefuroxime
More than 5 days: Piperacillin with taxobactam OR a broad-spectrum cephalosporin (ceftazidime) OR a quinolone (ciprofloxacin)
Which two antibiotics are options for treating acute pyelonephritis (upper UTI)?
Broad-spectrum cephalosporin OR quinolone
How would local impetigo be treated? What about if it is widespread?
Local: topical hydrogen peroxide
Widespread: oral flucloxacillin or erythromycin
Flucloxacillin is first-line for treating cellulitis. Which antibiotic is first-line if the cellulitis is near the eyes or nose?
Co-amoxiclav
Which antibiotic is first-line for managing animal or human bites?
Co-amoxiclav
Antibiotics for Ear/Nose/Throat
-Throat infections- phenoxymethylpenicillin
-Sinusitis- phenoxymethylpenicillin
-Otitis media- _ (erythromycin is allergic)
-Otitis externa- _ (erythromycin if allergic)
-Periodontal abscess- amoxicillin
Gingivitis- _
Amoxicillin
Flucloxacillin
Metronidazole
Which antibiotic is used to treat gingivitis?
Metronidazole
Which antibioitc is used to treat throat infections?
Phenoxymethylpenicillin
Which antibiotic is first-line for treating uncomplicated chlamydia? What about in allergies/pregnancy/breastfeeding?
Doxycycline 100mg BD for 7 days
Azithromycin second-line
How is gonorrhoea treated?
Intramuscular ceftriaxone
How is pelvic inflammatory disease treated?
Oral ofloxacin + oral metronidazole OR
IM ceftriaxone +oral doxycycline + oreal metronidazole
How is bacterial vaginosis treated?
Oral or topical metronidazole OR topical clindamycin
Which antibiotic is used to treat salmonella, shigellosis and campylobacter enteritis?
Ciprofloxacin
Gentamicin
Side-effects include:
-Ototoxicity, due to auditory or vestibular nerve damage (irreversible)
-Nephrotoxicity (risk increased by use alongside _)
CI in myasthenia gravis.
Monitoring of both peak (1 hour after administration) and trough (just before next dose) should be done. If trough level high= increase dosing interval.
If the peak is high then the dose should be decreased.
Furosemide
Management of Community-Acquired Pneumonia
Uncomplicated:
-_ is first-line for 5 days
-Doxycycline or clarithromycin in penicillin allergy
Moderate and high severity:
-Dual antibiotic therapy; amoxicllin + macrolide for 7-10 days
What is the maximum recommended treatment duration for gentamicin?
7 days
Why is chloramphenicol contraindicated for use in pregnancy?
Can cause ‘grey baby’ syndrome
Scabies Treatment
-Permethrin is first-line. Whole family should be treated, applied to the whole body, leave for 8-12 hours before washing and repeating _ week later.
One
What is the incubation period for chicken pox?
11-20 days
What is the incubation period for slapped cheek?
13-18 days
What is the incubation period for whooping cough?
7-10 days
What is the incubation period for mumps?
15-24 days
When would co-amoxiclav be used?
To treat infections that are resistant to amoxicllin by itself
How is Kawasaki disease treated?
Aspirin and IV immunoglobulin
HPV can cause warts.
True or False?
True
German measles can be very serious if caught by a pregnant lady in the first 20 weeks. Why is that?
Can disrupt the development of the baby and cause health issues
What is a key differentce between german measles and regular measles?
Regular measles manifests itself by producing white spots in the mouth as a symptom
Antimalarial prophylaxis should be continued for 4 weeks after leaving the endemic area, with the exception of which antimalarial?
Malarone
Which group of antibiotics can lower the seizure threshold?
Quinolones (risk is further increased by use alongside NSAIDs)
Which antibioitic is first-line for treating lyme disease?
Doxycycline 100mg BD for 21 days
Amoxicillin 2nd line: 1000mg TDS for 21 days
Azithromycin third line
Which parasite is the most common cause of infectious gastroenteritisis in the world?
Gardia Lamblia
What is the parasitic name for scabies?
Sarcoptes scabiei
What is the parasitic name for head lice?
Pediculus humanus capitis
What is the parasitic name for threadworm?
Enterobius vermicularis
Which three antibiotics should be taken with a full glass of water?
Clindamycin
Doxycycline
Metronidazole
With which three antibiotics should indigestion remedies be avoided two hours before and after?
Azithromycin
Minocycline
Doxycycline
With which three antibioitcs should milk, indigestion remedies, zinc and iron be avoided?
Oxytetracycline
Ciprofloxacin
Tetracycline
What is the mechanism of action for tetracyclines?
Inhibit the 30S ribosomal subunit, hindering the binding of the aminoacyl-tRNA to the acceptor site on the mRNA-ribosome complex
What is the mechanism of action of pencillins?
Kill bacteria through the binding of the beta-lactam ring to DD-transpeptidase, inhibiting its ross-linking activity and preventing new cell wall formation.
What is the mechanism of action of cephalosporins?
Similar to penicillins: bind to penicillin-binding proteins and interfere with cell wall enzymes.
What is the mechanism of action of macrolides?
Bind to bacterial 50S ribosomal subunits and cause the cessation of bacterial protein synthesis.
What is the mechanism of action of aminoglycosides?
Bind to the aminoacyl site of 16S ribosomal RNA within the 30S ribosomal subunit, leading to misreading of the genetic code.
What should be monitored if clindamycin treatment exceeds 10 days?
Liver and renal function
What should be monitored during vancomycin treatment?
Renal function
Urinalysis
FBC
Which antimalarial is contraindicated in patients with a history of psychiatric disease?
Mefloquine
What is the maximum recommended treatment length with gentamicin?
7 days
What is polyuria?
Excessive urinating
What is polydipsia?
Excessive thirst
What is the mechanism of action of rifampicin?
Inhibits RNA synthesis
What is the mechanism of action of sulphonamides?
Inhibits folic acid formation
What is the first-line antibiotic choice for pyelonephritis?
Cefalexin: 500 mg twice or three times a day (up to 1 to 1.5 g three or four times a day for severe infections) for 7 to 10 days
Can also use co-amoxiclav or trimethoprim if susceptible, and also ciprofloxacin (consider safety issues)
How often should gentamicin levels be measured in an elderly patient?
Every 3 or 4 doses, and after every dose change
