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Some bacteria have already become resistant to ceftazidime with avibactam (Zavicefta; Pfizer), one of the newest antibiotics introduced to the NHS, results of a study conducted by researchers at the UK Health Security Agency (UKHSA) have revealed.
The study, published in Eurosurveillance on 10 April 2025, analysed data from 66,914 routine surveillance samples between 2016 and 2020 to determine if bacteria were resistant to ceftazidime with avibactam, which is used to treat multidrug-resistant Gram-negative pathogens.
The UKHSA said that the antibiotic is typically used to treat individuals who are infected with known multi-drug-resistant bacteria or after other antibiotics have failed.
As a ‘reserve’ classified antibiotic, ceftazidime with avibactam should be prescribed only in exceptional circumstances based on how difficult the infection is to treat.
The results showed that 4,200 out of 66,914 routine surveillance samples (6.3%; 95% confidence interval 6.1–6.4%) contained bacteria that were resistant to the drug. Percentage resistance per bacterial species varied over time, which stabilised as testing was established.
“Low levels of resistance were observed in the country, coinciding in some cases, with the presence of certain carbapenemase genes in bacteria,” the researchers concluded.
The researchers said that the implications of these findings for public health “highlight the importance of carbapenemase gene identification before ceftazidime/avibactam use”.
As a result, the study said: “Best practice is to establish individual patient treatment plans using microbiology and surveillance data.
“It is also important for microbiologists and clinicians to identify and report emerging resistance to ceftazidime/avibactam in bacteria to prevent its spread.”
In 2022, ceftazidime with avibactam was selected for the government’s subscription model pilot for incentivising new antibiotic development.
Since March 2017, the antibiotic has been used by 69.5% of NHS trusts in England, with monthly usage progressing from 21 to 744 defined daily doses in March 2020.
Colin Brown, deputy director at the UKHSA responsible for antimicrobial resistance (AMR), said: “This study reminds us how important resistance surveillance is. Research like this means clinicians and prescribers can access the most relevant information available to prescribe the best antibiotics for their patients, while protecting the long-term effectiveness of antibiotics for future use.
“We aren’t going to be able to tackle antibiotic resistance solely by finding new drugs. While we continue to support innovation in developing new treatments, resistance will emerge and so it’s important that we all work together to keep antibiotics working.”
Commenting on the study, Claire Anderson, president of the Royal Pharmaceutical Society, said: “This study further highlights the urgent need to tackle AMR through a range of measures. From appropriate prescribing in line with national guidelines, to ensuring patients take antibiotics as directed, complete the full course and never share them with others, there are practical steps we can all take to help reduce resistance.
“Pharmacists play a vital role in this effort, supporting patients to manage common conditions that don’t require antibiotics and providing expert advice when antibiotics are necessary.”
