Antibiotic use & susceptibility patterns

• Awanui Labs – urine antibiograms 2025
• Awanui Labs – Staphylococcus and Streptococcus antibiograms 2025

• Awanui Labs Bloodstram infection (BSI) data – South Island – 2025
• Bloodstream infection (BSI) antibiogram for CCHV neonatal patients 2025
• Bloodstream infection (BSI) antibiogram for CCHV patients 2025

Data derived from community urine samples. E. coli is the commonest urinary isolate by a huge margin. Duplicate isolates from the same person in the same year with the same resistance pattern are removed. ESBL/ampC production is inferred from resistance to any third-generation cephalosporin. Percentage of isolates with ESBL/ampC production is also presented by prioritised ethnicity, due to the known association between gram negative resistance and ethnicity in the NZ context.

Commentary

• Susceptibility to the common E. coli oral agents is relatively stable over time across the regions although there are some regional differences.
• Nitrofurantoin resistance remains very rare, despite significant increases in usage over time.
• There does appear to be an ongoing slow rise in the proportion of isolates that are ESBL or ampC producers across the regions.
• When examined by ethnicity there are pronounced differences in the proportion of isolates with ESBL/ampC production, particularly in those of Indian ethnicity, in whom the proportion is rising rapidly.

E. coli main agents – community urine charts

E. coli ESBL/ampC producers – community urine charts- by ethnicity

Data are derived from Awanui Labs that perform testing for public hospitals. E. coli is the commonest blood culture isolate. Duplicate isolates from the same person in the same year are removed. ESBL/ampC producers are not specifically reported; however, this can be inferred as the inverse to the % susceptible to ceftriaxone. The incidence charts are not yet reported by age band – to follow.

Commentary

• Similar to the urine susceptibility charts, the proportion of bloodstream E. coli isolates with ESBL/ampC production is rising. This is seen as a reduction in ceftriaxone susceptibility over time.

Data derived from community urine samples. K. pneumoniae is the second commonest urinary isolate. Duplicate isolates from the same person in the same year with the same resistance pattern are removed. ESBL/ampC production is inferred from resistance to any third-generation cephalosporin. Due to lower numbers, ESBL/ampC production by ethnicity is not reported.

Commentary

• Susceptibility to the common oral agents is relatively stable over time.
• The proportion of isolates with ESBL/ampC production has seen minor fluctuations over the time period, with the suggestion of a slow rise over the past 3-4 years.

Data are derived from Awanui Labs that perform testing for public hospitals. K. pneumoniae is the second commonest gram-negative blood culture isolate but is far less common than E. coli. Duplicate isolates from the same person in the same year are removed. ESBL/ampC producers are not specifically reported; however, this can be inferred as the inverse to the % susceptible to ceftriaxone.

Commentary

• Allowing for year-on-year variability, susceptibility to the main agents is relatively stable over time.
• There was a significant reduction in incidence in CCHV and Wairarapa in 2022. The reason for this is unclear at this point.

These data are derived from community swab samples. S. aureus is by far the commonest Gram-positive organism isolated. Duplicate isolates from the same person in the same year with the same resistance pattern are removed. Data are presented here for all S. aureus (methicillin susceptible and resistant – MSSA and MRSA) and for MRSA only.

Commentary

• In the past 2-3 years there has been a gradual reduction in flucloxacillin susceptibility (i.e. an increase in MRSA). MRSA is more common further north in New Zealand.
• Fusidic acid susceptibility has improved dramatically across the time period.
• Co-trimoxazole and doxycycline remain reliable agents for both MSSA and MRSA.
• Similar to Gram-negative resistance, there are clear differences in the proportion of S. aureus isolates that are MRSA according to ethnicity, with recent significant rises in those of Indian ethnicity.

Staphylococcus aureus – main agents – community swab isolates

MRSA – main agents – community swab isolates

MRSA – community swab isolates – by ethnicity

Data are derived from Awanui Labs that perform testing for public hospitals. S. aureus is the second commonest blood culture isolate. Duplicate isolates from the same person in the same year are removed. MRSA is not specifically reported; however, this can be inferred as the inverse to the % susceptible to cefazolin/flucloxacillin. It would be preferable to separate the incidence charts into community and healthcare-associated, however this is not currently possible with the available data. The incidence charts are not yet reported by age band – to follow.

Commentary

• MRSA bloodstream infection is less common in the South Island hospitals, however this does appear to be gradually increasing over time.
• Clindamycin susceptibility also appears to be gradually reducing. Susceptibility to other agents appears stable.
• The lower penicillin susceptibility in South Island hospitals is likely an artefact due to a lower proportion of isolates being tested in those laboratories.

Data are derived from Awanui Labs that perform testing for public hospitals. S. pneumoniae is the second commonest community-onset gram-positive isolate. Duplicate isolates from the same person in the same year are removed. Susceptibility to common agents is reported in broad categories of S vs R for all locations. Specific MICs for the three common beta-lactam agents are limited to CCHV and Wairarapa because all isolates have MIC testing in these labs (since 2023), whereas testing is selective elsewhere. The incidence charts are not yet reported by age band – to follow.

Commentary

• The absolute number of positive blood cultures is currently rising.
• Resistance to the two main agents used to treat community-acquired pneumonia (amoxicillin and ceftriaxone) remains very rare.
• MICs to amoxicillin and ceftriaxone remain very low. Isolates with ceftriaxone MICs above the meningitis breakpoint are very rare in CCHV and Wairarapa.
• Penicillin MICs remain within the range that is suitable for non-meningitis indications for the vast majority.
• Sputum isolates display resistance to common oral agents far more commonly than invasive isolates. This is likely due to the fact that sputum commonly detects commensal organisms that are more likely to acquire resistance, but less likely to cause invasive disease. This is why sputum susceptibility patterns should not be used to determine suitable agents for treatment of invasive disease.

These data are presented to demonstrate the effects of AMR on the ability to treat common UTI organisms in the community setting. Difficult to treat organisms increase the risk of empiric treatment failure and may mean UTIs that could otherwise be treated with oral therapy require intravenous therapy. To be included, organisms must have been tested for all of the listed agents, which means numbers may fluctuate over time due to changes in lab methods.

Commentary

• Organisms testing resistant to all available oral agents suitable for uncomplicated UTI (i.e. cystitis) remain very rare in the community setting. A significant contributor to this is the reliability of nitrofurantoin.
• Organisms testing as resistant to all available oral agents suitable for treating complicated UTI are more common, with recent increases in absolute numbers. These results are derived from all urinary isolates (it is currently difficult to determine based on laboratory data on a large scale which patients have complicated UTI), so they are indicative only.

Data derived from all sample types across all Awanui Labs. Duplicate isolates from the same person with the same organism are removed. Due to changes in reporting over time it is difficult to extract the specific carbapenemase types from older data, however this reporting is now more robust.

Commentary

• CPOs represent the highest threat organisms from an AMR perspective.
• They remain rare in Aotearoa but detections are increasing significantly over time.
• They are predominantly detected in people who have recently arrived from or travelled overseas (especially if receiving healthcare overseas) – this is why the COVID/lockdown years saw reduced numbers.

CPOs by organism

CPOs by gene

CPOs by hospital community

CPOs by sample type

Note: many of these agents may require adjustment with significant renal impairment. Seek ID or pharmacy advice if necessary.

Oral agents:

• Amoxicillin  – 1g tds
• Augmentin – use ‘boosted augmentin’ (Augmentin 625mg tds + amoxicillin 500mg tds)
• Ciprofloxacin – 750mg bd
• Co-trimoxazole – 1440mg bd or 960mg tds

IV agents:

• Amoxicillin – 1g q6h (standard dose sufficient for ‘I’ when given IV). If patient septic or >100kg use 2g q6h.
• Augmentin – 1.2g q8h (standard dose sufficient for ‘I’ when given IV). If patient septic or >100kg use ‘boosted IV augmentin’ (Augmentin 1.2g q8h + Amoxicillin 1g q8h)
• Benzylpenicillin 2.4g q6h
• Ceftazidime – 2g q8h
• Cefepime – 2g q8h
• Piperacillin-tazobactam (Tazocin) – 4.5g q6h