Which antibiotics to use (for medical students)

Meningitis (caused by Listeria) (in hospital)

(Amoxicillin or ampicillin '21 days') + gentamicin (7 days) ALT: co-trimoxazole '21 days'

Endocarditis caused by hameophilus, actinobacillus, cardiobacterium, eikenella, or kingella ('HACEK' organisms)

(Amoxicillin or ampicillin '4-6 wks') + low-dose gentamicin (2 wks) IF (amoxi-resistant): change amoxi to ceftriaxone

Chronic bronchitis: acute exacerbations

(Amoxicillin or ampicillin) '5 days' OR a tetracycline '5 days' ALT: (clarithro-, erythro-, or azithro- mycin) '5 days'

Community-acquired pneumonia (moderate-severity)

(Amoxicillin or ampicillin) + (clarithro-, erythro-, or azithro- mycin) '7 days, 14-21 for staph' OR doxycycline alone IF (MRSA), add (vancomycin or teicoplanin)

Endocarditis caused by enterococci (eg. Enterococcus faecalis)

(Amoxicillin or ampicillin) + gentamicin (4-6 wks) ALT: (vancomycin or teicoplanin) + gentamicin IF (gent-resistant): change gent to streptomycin

Meningitis (caused by Haemophilus influenzae) (in hospital)

(Cefotaxime or ceftriaxone) '10 days' ALT: chloramphenicol Consider adjunctive dexamethasone.

Meningitis (caused by pneumococci) (in hospital)

(Cefotaxime or ceftriaxone) '14 days' IF (penicillin sens): use benzylpencillin instead. IF (penicillin/cephalosporin resistant): add vancomycin +/- rifampicin. Consider adjunctive dexamethasone.

Meningitis (unknown cause) (in hospital, in 3 month old to 50 year old.)

(Cefotaxime or ceftriaxone) 'at least 10 days' IF (recent abx, travel outside UK): consider adding vancomycin. Consider adjunctive dexamethasone.

Meningitis (unknown cause) (in hospital, in adults over 50yo.)

(Cefotaxime or ceftriaxone) + (amoxicillin or ampicillin) 'at least 10 days' IF (recent abx, travel outside UK): consider adding vancomycin. Consider adjunctive dexamethasone.

Prostatitis (acute)

(Ciprofloxacin or ofloxacin) '28 days' ALT: trimethoprim '28 days'

Pneumonia caused by atypical pathogens (eg. legionella, chlamydial, mycoplasma)

(Clarithro-, erythro-, or azithro- mycin) '14 days' ALT: a quinolone (for legionella), or doxycyline (for chlamydial/mycoplasma)

Pneumonia caused by chlamydial or mycoplasma

(Clarithro-, erythro-, or azithro- mycin) '14 days' ALT: doxycycline

Pneumonia caused by legionella

(Clarithro-, erythro-, or azithro- mycin) '7-10 days' ALT: a quinolone (eg. ciprofloxacin) IF (high severity), add (Clarithro-, erythro-, or azithro- mycin) OR rifampicin for first few days

Endocarditis: initial 'blind' therapy

(Flucloxacillin OR benzylpenicillin if less severe) + Gentamicin ALT (if resistant, or prostheses present): vancomycin + rifampicin + gentamicin

Septicaemia (community-acquired)

A broad-spectrum anti-pseudomonal penicillin (eg. tazocin or ticarcillin with clavulanic acid) OR a broad-spectrum cephalosporin (eg. cefuroxime). IF (MRSA): add vancomycin or teicoplanin. IF (anerobic): cefuroxime + metronidazole IF (resistant): meropenem.

Septicaemia (hospital-acquired)

A broad-spectrum antipseudomonal beta-lactam antibacterial (e.g. piperacillin with tazobactam, ticarcillin with clavulanic acid, ceftazidime, imipenem with cilastatin, or meropenem). IF (MRSA): add vancomycin or teicoplanin. IF (anerobic): cefuroxime + metronidazole

Pyelonephritis (acute)

A broad-spectrum cephalosporin '10-14 days' OR a quinolone (eg. ciprofloxacin) '10-14 days'

Peritonitis

A cephalosprin + metronidazole OR gentamicin + metronidazole OR gentamicin + clindamycin OR piperacillin with tazobactam (tazocin) alone

Community-acquired pneumonia (low-severity)

Amoxicillin or ampicillin (7 days, 14-21 for staph) IF (atypical), add (clarithro-, erythro-, or azithro- mycin) ALT: doxycline OR (clarithro-, erythro-, or azithro- mycin)

Hospital-acquired pneumonia (late-onset, after 5 days post-admission)

An antipseudomonal penicillin (eg. tazocin) '7 days' OR broad-spectrum cephalosporin (eg. ceftazidime) OR another antipseudomonal beta-lactam OR a quinolone (eg. ciprofloxacin) IF (MRSA): add vancomycin IF (pseudomonas aeruginosa): consider adding aminoglycoside (eg. amikacin, gentamicin)

Native-valve endocarditis caused by fully sensitive streptococci (eg. viridans streptococci)

Benzylpenicillin (4 weeks) ALT: vancomycin (4 weeks) If large/abscess/infected emboli = benzylpenicillin + gentamicin (2 weeks)

Native-valve endocarditis caused by less-sensitive streptococci.

Benzylpenicillin (4-6 wks) + gentamicin (2 wks) ALT: 'vancomycin or teicoplanin (4-6 wks)' + gentamicin (2 wks)

Prosthetic valve endocarditis caused by streptococci.

Benzylpenicillin (6 wks) + gentamicin (2 wks) ALT: 'vancomycin or teicoplanin (6 wks)' + gentamicin (2 wks)

Meningitis (caused by meningococci) (in hospital)

Benzylpenicillin (7 days) OR (cefotaxime or ceftriaxone) ALT: chlorampenhicol

Community-acquired pneumonia (high severity)

Benzylpenicillin + (clarithro-, erythro-, or azithro- mycin) '7-10 days, 14-21 for staph' OR Benzylpenicillin + doxycycline ALT: (cefuroxime or cefotaxime or ceftriaxone) + (clarithro-, erythro-, or azithro- mycin). IF (life-threat, gram-neg, or nursing home): Co-amoxiclav + (clarithro-, erythro-, or azithro- mycin) IF (MRSA), add (vancomycin or teicoplanin)

Haemophilus influenzae epiglottitis

Cefotaxime OR ceftriaxone ALT: chloramphenicol

Purulent conjunctivitis

Chloramphenicol eye drops

Biliary-tract infection

Ciprofloxacin OR gentamicin OR a cephalosporin

Hospital-acquired pneumonia (early-onset, within 5 days after admission)

Co-amoxiclav (7 days) OR cefuroxime (7 days) IF (life-threat, recent abx, or resistant) treat as late-onset

Throat infections (bacterial suspected)

Consider bacterial if history of valvular heart disease, systemic upset, increased risk (eg. immunosuppressed). Phenoxymethylpenicillin (10 days) ALT: (Clarithro-, erythro-, or azithro- mycin) '10 days'

Sinusitis (bacterial suspected)

Consider bacterial if persistent and purulent discharge >7 days, severe, or high risk. (Amoxicillin or ampicillin) '7 days' OR doxycycline (7 days) OR (Clarithro-, erythro-, or azithro- mycin) '7 days' IF (no improvement in 48 hrs): oral co-amoxiclav. IF (severe) initial IV co-amoxiclav OR cefuroxime

Septicaemia (related to vascular catheter)

Consider removing vascular catheter. (Vancomycin or teicoplanin) IF (gram-neg): add broad-spectrum antipseudomonal beta-lactam (eg. tazocin).

Animal and human bites

Consider tetanus vaccination/immunoglobulin +/- rabies prophylaxis. Assess risk of blood-borne viruses. Co-amoxiclav ALT: doxycycline + metronidazole

Late latent syphillis (asymptomatic infection of more than 2 years)

Contact tracing recommende. Benzathine benzylpenicillin (once weekly for 2 weeks) ALT: doxycyline (28 days)

Genital chlamydial infection (uncomplicated)

Contact tracing recommended. Azithromycin (single dose) OR doxycyline (7 days) ALT: erythromycin (14 days)

Non-gonococcal urethritis

Contact tracing recommended. Azithromycin (single dose) OR doxycyline (7 days) ALT: erythromycin (14 days)

Non-specific genital infection

Contact tracing recommended. Azithromycin (single dose) OR doxycyline (7 days) ALT: erythromycin (14 days)

Early syphillis (infection less than 2 years)

Contact tracing recommended. Benzathine benzylpenicillin (single dose) ALT: doxycyline (14 days) OR erythromycin (14 days)

Pelvic inflammatory disease

Contact tracing recommended. Doxycyline + metronidazole (14 days) + IM ceftriaxone (single dose) OR ofloxacin + metronidazole (14 days)

Gonorrhoea (uncomplicated)

Contact tracing recommended. Consider chlamydia co-infection. Azithromycin + IM ceftriaxone (single dose each) ALT (oral): Cefixime + azithromycin (single dose each) ALT (if quinolone sens) ciprofloxacin + azithromycin

Asymptomatic contacts of patients with infectious syphillis.

Doxycycline (14 days)

Otitis externa

Flucloxacillin ALT: (Clarithro-, erythro-, or azithro- mycin) IF (pseudomonas): ciprofloxacin OR aminoglycoside (eg. gentamicin)

Endocarditis caused by staphylococci

Flucloxacillin (4-6 weeks) Add rifampicin for at least 2 weeks if prosthetic valve endocarditis. ALT: vancomycin + rifampicin

Cellulitis (localized or diffuse inflammation of connective tissue with severe inflammation of dermal and subcutaneous layers of the skin)

Flucloxacillin (high-dose) ALT: clindamycin OR (Clarithro-, erythro-, or azithro- mycin) OR (vancomycin or teicoplanin) IF (gram-neg): broad-spectrum antibacterials

Meningococcal septicaemia

Give immediate dose. Benzylpenicillin OR (cefotaxime or ceftriaxone) ALT: chloramphenicol

Otitis media

Most caused by viruses, or self-limited. Treat if not improved after 72 hrs or deterioration. (Amoxicillin or ampicillin) '5 days' ALT: (Clarithro-, erythro-, or azithro- mycin) '5 days' IF (no improvement >48 hrs): co-amoxiclav

Typhoid fever

Multi-resistant (test sensitivity) Cefotaxime or ceftriaxone ALT: Azithromycin OR ciprofloxacin (if sens)

Salmonella (non-typhoid)

NI unless immunocompromised or severe infection - Ciprofloxacin OR cefotaxime.

Campylobacter enteritis

NI unless immunocompromised or severe infection - Clarithro-, azithro-, OR erythro- mycin. ALT: ciprofloxacin.

Pericoronitis (gum inflammation around erupting tooth)

NI unless systemic features or persistent. Metronidazole (3 days) ALT: amoxicillihn (3 days)

Gingivitis

NI unless systemic features or persistent. Metronidazole (3 days) ALT: amoxicillin (3 days)

Gastroenteritis

NI. (Frequently self-limiting, may not be bacterial)

Shigellosis

Only treat if more than mild - Ciprofloxacin OR azithromycin ALT (if sens): Amoxicillin OR trimethoprim

Impetigo (widespread infection)

Oral flucloxacillin (7 days) ALT: oral (Clarithro-, erythro-, or azithro- mycin) IF (streptococci): add phenoxymethylpenicillin

Clostridium difficile

Oral metronidazole (10-14 days) OR (for 3rd or severe infection) oral vancomycin (10-14 days) IF (not responding or very severe) add IV metronidazole

Bacterial vaginosis

Oral metronidazole (5-7 days) ALT: topical metronidazole (5 days) OR topical clindamycin (7 days)

Erysipelas (streptococcus infection of superficial skin, with well-defined edge)

Phenoxymethylpenicillin (7 days) OR benzylpenicillin ALT: clindamycin OR (Clarithro-, erythro-, or azithro- mycin) IF (severe): high-dose flucloxacillin

Impetigo (small areas of skin infected)

Seek microbiology advice before using topical treatment in hospital. Topical fusidic acid (7 days) IF (MRSA): topical mupirocin (7 days)

Osteomyelitis

Seek specialist advice if chronic or prostheses. Flucloxacillin (6 wks) +/- (fusidic acid or rifampicin '2 wks') ALT: change fluclox to clindamycin IF (MRSA): change fluclox to (vancomycin or teicoplanin)

Septic arthritis

Seek specialist advice if prostheses present. Flucloxacillin (4-6 wks) ALT: clindamycin (4-6 wks) IF (MRSA): (vancomycin or teicoplanin) IF (gonococcal or gram-neg) (cefotaxime or ceftriaxone)

Meningitis (initial empirical therapy)

Transfer to hospital urgently. Benzylpenicillin 1.2g (IM/IV) immediately ALT: cefotaxime or chloramphenicol

Mastitis during breastfeeding

Treat if severe, or persistent >12-24 hrs, or infected. Flucloxacillin (10-14 days) ALT: erythromycin (10-14 days) Continue breastfeeding throughout.

Urinary tract infection (lower)

Trimethoprim (7 days) OR nitrofurantoin (7 days) ALT: (amoxicillin or ampicillin) OR oral cephalosporin (eg. cefachlor) Can treat for just 3 days in uncomplicated female UTIs