Updates

What's New in Antibiotic

March 2025

The Antibiotic guidelines provide advice on managing almost 200 unique infections; from self-limiting infections treated in primary care, to life-threatening infections requiring intensive care support. This review of the guidelines has been staggered, with 3 main groupings of topics.

  1. Topics completely revised or newly developed for the March 2025 release.
  2. Topics under revision that will be published later in 2025 or 2026. To ensure alignment across the guidelines, some of these topics have been amended in the March 2025 release (identified by an amended date on the topic’s page).
  3. Topics that have recently undergone a complete review and did not require further comprehensive review for the March 2025 release. To ensure alignment across the guidelines, some of these topics have been amended in the March 2025 release (identified by an amended date on the topic’s page).

For important changes in this release, see:

Guideline-wide changes for changes impacting multiple topics.
New content and updates to revised topics for a selection of key updates and new content;
Interim updates to topics under revision.

Areas in which evidence was lacking, insufficient or conflicting, and for which further research is warranted were identified during this update. To support the research community, these evidence gaps are available on our website.

Guideline-wide changes

The following changes have been made across the Antibiotic guidelines, including topics under revision and previously revised topics, but not in other guideline titles where antimicrobials are recommended.
  • Whenever an antimicrobial that requires dosage adjustment in kidney impairment is recommended for treatment of infection in adults, a link has been added from the drug recommendation to the advice on dosage adjustment. Links are not included if the antimicrobial does not require dosage adjustment, or for children.
  • Whenever an antimicrobial that requires dosage adjustment in kidney impairment is recommended for surgical or endocarditis prophylaxis in adults, advice is included in the drug recommendation. Advice is not included if the antimicrobial does not require dosage adjustment when used as a single perioperative dose.
The following changes have been made across the Antibiotic guidelines, including topics under revision and previously revised topics, and in other guideline titles where antimicrobials are recommended.
  • Intravenous amoxicillin+clavulanate dosages have been updated to include dosage options for both formulations in adults and children who weigh more 40 kg.
  • In children, adherence to a 6-hourly dosage regimen of cefalexin can be difficult. To address this issue, some cefalexin recommendations (eg for cellulitis and pyelonephritis) now include an option for 8-hourly dosing using a higher dose.
  • Doxycycline recommendations are now included for the treatment of infections in children younger than 8 years, provided the duration of therapy is less than 21 days (eg for bronchiectasis exacerbations). When used short term, doxycycline has not been associated with tooth discolouration, enamel hypoplasia or bone deposition.
  • To ensure adequate drug exposure in critically-ill patients, a higher initial dosage of meropenem is recommended for treatment of suspected or confirmed infection with Pseudomonas aeruginosa, Burkholderia pseudomallei or Acinetobacter baumannii, because some isolates have a high minimum inhibitory concentration (MIC).
  • For suspected or confirmed pseudomonal infections, administering piperacillin+tazobactam over 3 hours is preferred to ensure adequate drug exposure. If this is not possible (eg the patient is receiving other drugs via the same line), administration over 30 minutes is an alternative.
  • When meropenem or piperacillin+tazobactam is used in critically ill patients, administering the total daily dose as a continuous infusion over 24 hours is preferred to ensure adequate drug exposure.
  • In hospitalised patients with severe immediate penicillin hypersensitivity, a cephalosporin is recommended for initial intravenous therapy for infection where there are superior treatment outcomes with beta-lactam therapy.
  • Aminoglycoside dose recommendations for treatment of infection have been updated for adults and children. For adults, lean body weight is recommended to calculate the aminoglycoside dose except when aminoglycosides are used for synergistic therapy of endocarditis or surgical prophylaxis. Aminoglycoside initial dose calculators for treatment of infection in adults have been developed for amikacin, gentamicin and tobramycin. These calculators cannot be used for synergistic therapy or surgical prophylaxis.
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New content and updates to revised topics

A selection of important changes in the topics completely revised or newly developed for the March 2025 release.

Changes impacting multiple topics

  • When aminoglycosides are recommended for treatment of infection, tobramycin is now included alongside gentamicin. Tobramycin and gentamicin are ranked equally except if Pseudomonas aeruginosa is suspected or proven, in which case tobramycin is preferred.
  • For directed therapy of Staphylococcus aureus infections (eg bacteraemia, pneumonia, staphylococcal scalded skin syndrome), cefazolin is now recommended as an equal first-line alternative to flucloxacillin. Evidence suggests that cefazolin is equally effective for methicillin-susceptible S. aureus and it may have a lower risk of acute kidney injury.
  • For directed therapy of P. aeruginosa infections (eg pneumonia, bacteraemia or sepsis, bronchiectasis exacerbations in adults and children), cefepime is now recommended alongside ceftazidime or piperacillin+tazobactam as an antipseudomonal beta lactam.
  • To ensure adequate drug exposure, oral amoxicillin+clavulanate 875+125 mg dosed 8-hourly is now recommended for serious infections that are suspected or confirmed to be caused by Enterobacterales or Haemophilus influenzae when either adequate source control has not been achieved, or intravenous to oral switch occurs early.
  • A 2 g daily dose of ceftriaxone is increasingly recommended but a 1 g daily dose continues to be recommended in specific scenarios; an explanation of the variety of doses used has been included.
  • In this update, ceftriaxone is usually preferred to cefotaxime in adults because ceftriaxone requires less frequent dosing. If S. aureus is a likely pathogen, cefotaxime monotherapy may be recommended because it has superior intrinsic activity against staphylococci. If ceftriaxone is used in this situation, it is combined with flucloxacillin.
  • Rates of resistance to clindamycin are rising in methicillin-resistant Staphylococcus aureus (MRSA). For intravenous therapy of serious infections caused by MRSA (eg suspected staphylococcal septic arthritis of a native joint), vancomycin is preferred to clindamycin. However, in some regions, based on local susceptibility data, clindamycin may be a suitable alternative. For oral therapy of MRSA infections, trimethoprim+sulfamethoxazole is usually preferred to clindamycin because of a favourable resistance profile; it also has better palatability in children.

Cardiovascular infections

  • Commentary on the role of partial oral therapy for infective endocarditis is included.
  • New content has been developed on managing infective endocarditis in people who inject drugs, because injecting drug use is a common predisposing factor for infective endocarditis. Details are included on the likely pathogens in this population, and specific management considerations for staphylococcal endocarditis. A printable patient information sheet details how to use drugs more safely to reduce risk of infection.
  • For patients with a cardiac implantable electronic device and bacteraemia, new advice details the approach to management when a cardiac implantable electronic device infection is suspected but not proven.
  • A new topic on infections associated with intravenous catheters has been developed, providing advice on the management of a suspected bloodstream infection or local infection associated with an intravenous catheter.

Cryptococcosis

  • Management of cryptococcosis (both pulmonary cryptococcosis and cryptococcal meningitis) is now included in a single topic to improve usability.
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Infectious diarrhoea

  • Faecal testing advice has been extensively updated, with new tables summarising indications for standard and specific faecal testing.
  • The initial management of acute infectious diarrhoea has been updated to prioritise supportive care and close follow-up, and limit antibiotic use in the Australian setting.
  • Empirical antibiotic therapy for travellers’ diarrhoea is no longer recommended for patients with moderate diarrhoea unless they are at increased risk of complications. Antibiotic therapy continues to be an option for patients with severe travellers’ diarrhoea.
  • Management of Clostridioides difficile infection differs in adults and children, and is further influenced by the severity of infection and whether it is a first episode or a recurrence. To aid navigation to the correct treatment regimen, algorithms have been developed for managing a new episode of diarrhoea in patients with risk factors for C. difficile infection.
  • For treatment of a first episode of mild to moderate C. difficile infection, vancomycin is now recommended first line, because evidence suggests vancomycin has greater efficacy than metronidazole.

Cervical lymphadenitis

  • Management of cervical lymphadenitis depends on the age of the patient and duration of symptoms; the scope of this topic has expanded to include management advice for adults and a new section on subacute cervical lymphadenitis.

Eye infections

  • Images of dacryocystitis and dendritic ulcer have been included to aid with diagnosis.
  • New printable handouts on eyelid hygiene for blepharitis are available to support patients to perform this key aspect of treatment.
  • Management advice for chlamydial and gonococcal conjunctivitis in neonates and children has been expanded.
  • To assist with diagnosis and management, a new table describes the comparative features and investigations for the different types of infectious keratitis.
  • Orbital (postseptal) cellulitis is an emergency but its features overlap with those of periorbital (preseptal) cellulitis. To support prompt diagnosis and escalation of therapy, distinguishing features of each infection are listed in a new table and are integrated into a new management algorithm.
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Genital and sexually transmissible infections

HIV

  • New content on indicator conditions for HIV testing has been added to the guidelines. All patients with indicator conditions should be offered HIV testing. Indicator conditions and the need for HIV testing are identified throughout the guidelines in relevant clinical topics (eg cryptococcal meningitis).

Intra-abdominal infections

  • A shorter duration of therapy is now recommended for many intra-abdominal infections, if adequate surgical source control is achieved.
  • The role of nonoperative treatment for acute uncomplicated appendicitis is discussed and accompanied by a new algorithm that outlines the approach to managing acute uncomplicated appendicitis and helps assess the appropriateness of nonoperative treatment.
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Pneumonia

  • To improve usability, the pneumonia topics have been significantly restructured. To find the right pneumonia topic in these guidelines, see Figure 2.46.
Community-acquired pneumonia (CAP)
  • Rather than using pneumonia severity scoring tools to assess the severity of CAP in adults, the Antibiotic Expert Group recommend using the features that may indicate hospital admission and the red flags for intensive care support.
  • A new table provides clearer guidance on the clinical and microbiological investigations for CAP in adults, depending on the severity of pneumonia.
  • Management of CAP in tropical regions of Australia has been integrated into the standard treatment topics to support routine consideration of pathogens commonly seen in these areas (eg Burkholderia pseudomallei, Acinetobacter baumannii).
  • Advice on the approach to empirical antiviral therapy for suspected viral CAP has been added.
  • Intravenous hydrocortisone is recommended within 24 hours of diagnosis for critically unwell adults with high-severity CAP who require high-flow oxygen or mechanical ventilation (invasive or noninvasive), or if there is a concurrent indication for use (eg a COPD exacerbation).
Hospital-acquired pneumonia (HAP)
  • The definition of hospital-acquired pneumonia has been updated to include patients who have been discharged within the previous 7 days from a hospital admission of longer than 48 hours, as well as patients hospitalised in acute care for longer than 48 hours.
  • The definition of high-severity HAP has been clarified, noting that patients with sepsis are always considered to have high-severity HAP.
  • The criteria for using intravenous therapy in patients with low- to moderate-severity HAP have been updated.
Ventilator-associated pneumonia (VAP)
  • The empirical therapy regimens for ventilator-associated pneumonia are now stratified according to the risk of Pseudomonas aeruginosa. Monotherapy with ceftriaxone or cefotaxime is recommended for patients considered at low risk of P. aeruginosa. For patients at increased risk of P. aeruginosa who receive antipseudomonal therapy initially, a step-down to narrower-spectrum intravenous therapy is no longer recommended. Instead, there is a greater emphasis on reviewing the diagnosis of VAP at 48 hours, and stopping therapy if there is no strong evidence to support the diagnosis.
Directed therapy for pneumonia
Aspiration pneumonia
  • The need to treat a broad range of oral anaerobes (eg Bacteroides and Prevotella species) in patients with suspected aspiration pneumonia is often overestimated. A new algorithm outlines the management of patients who have had an aspiration event. A second algorithm outlines the management of aspiration pneumonia in patients who are not improving on initial antibiotic therapy.
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Respiratory infections other than pneumonia

Antibiotic management of bronchiectasis
  • Bronchiectasis is potentially reversible in children so there is greater emphasis on referral to paediatric respiratory specialists, discussing management decisions with the treating specialist, using individualised management plans and eradicating newly identified Pseudomonas aeruginosa.
  • For both adults and children, new directed therapy recommendations are included for bronchiectasis exacerbations caused by Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae and P. aeruginosa.
Antibiotic management of chronic obstructive pulmonary disease (COPD) exacerbations
  • Antibiotic therapy is not routinely recommended for COPD exacerbations. A new algorithm helps clinicians to determine when to use antibiotic therapy.
Influenza
Parapneumonic effusion and thoracic empyema
  • New advice has been added on the management of thoracic empyema complicating thoracic trauma or haemothorax, complicating long-term indwelling pleural catheter, secondary to haematogenous seeding, and associated with surgical site infection.
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Prehospital management of meningitis and sepsis

  • Quick reference tables have been added that provide reconstitution and administration advice for ceftriaxone and benzylpenicillin for the pre-hospital management of patients with suspected meningitis or sepsis.

Sepsis and septic shock

  • A tiered approach to the timing of antimicrobial administration in patients with suspected sepsis has been implemented. The urgency of antimicrobial administration is influenced by whether the patient has septic shock, is immunocompromised or otherwise vulnerable to sepsis, and the certainty that organ dysfunction is due to infection.
  • The empirical regimens for sepsis or septic shock of unknown source are published in a suite of 5 topics that span a range of patient groups. New flowcharts are included to help navigation to the correct topic.
  • Drug recommendations have been added for hospital-acquired sepsis or septic shock in neonates and children younger than 2 months, and children 2 months or older.
  • For adults with community-acquired sepsis without septic shock who do not require intensive care support, a reduced dosing frequency of flucloxacillin and cefazolin is now recommended. Patients with septic shock or requiring intensive care support require more frequent dosing to ensure adequate drug exposure because they are more likely to have low serum albumin, impaired kidney function and be infected with a pathogen with a higher minimum inhibitory concentration (MIC).

Skin and soft tissue infections

  • Indications for initial intravenous therapy for cellulitis and erysipelas have been updated and simplified.
  • Cut-off periods for starting antiviral therapy for chickenpox in adults who are immunocompetent have been replaced with a recommendation to start antiviral therapy within 24 hours of rash onset for maximum benefit.
  • For mild infections of diabetes-related foot ulcers, a new algorithm outlines how to assess the risk of polymicrobial infection and guides antibiotic selection. The suggested duration of therapy is outlined in new tables that consider the degree of resection or debridement, location, and severity and extent of initial or residual infection.
  • Assessment and management of impetigo include a consideration of the patient’s risk of acute rheumatic fever, the nature (nonbullous or bullous) and number of sores, and whether the infection is recurrent. Images of bullous and nonbullous impetigo have been included to aid diagnosis.
  • New advice has been added on managing staphylococcal scalded skin syndrome in children.
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Urinary tract infections in adults

  • More detailed advice is now included on nonantibiotic therapy, as an alternative to antibiotic therapy, for acute cystitis in nonpregnant females younger than 65 years. The expanded text discusses potential benefits and harms of initial nonantibiotic therapy, as well as patient selection.
  • Nitrofurantoin is now recommended as the first-line treatment of acute cystitis in adults because of high trimethoprim resistance among Escherichia coli.
  • Changes made to the management of acute pyelonephritis in adults include:
    • Expanding the patient group for whom oral antibiotics can be used. Initial oral antibiotic therapy can usually be used for nonpregnant adults without sepsis or septic shock who can tolerate and absorb oral therapy.
    • Intravenous amoxicillin or ampicillin is no longer recommended as part of combination therapy for nonpregnant adults because of high resistance rates among E. coli and rare involvement of enterococci. Amoxicillin or ampicillin (with an aminoglycoside) continues to be recommended in pregnancy because of the increased risk of invasive group B streptococcus [GBS] infection.
  • Management of sepsis and septic shock from a urinary tract source in adults emphasises consideration of local resistance patterns and patient risk factors for infection with a resistant pathogen. Antibiotic regimens are separated into 3 sections, depending on the presence of pregnancy and septic shock.
  • To minimise the use of continuous antibiotic prophylaxis for recurrent UTI in nonpregnant adults, nonantibiotic strategies, intermittent postcoital prophylaxis and patient-initiated treatment are emphasised.

Urinary tract infections in children

Managing suspected infection with a multidrug-resistant gram-negative bacterium

Principles of vancomycin use in young infants and children

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Principles of vancomycin use in adults

Penicillin hypersensitivity


Interim updates to topics under revision

In response to changes made to topics completely revised or newly developed for the March 2025 release, the following changes have been made to some topics under revision:
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