Prescribing more antibiotics to patients undergoing joint replacement surgery does not prevent infections despite being a common practice, a large Australian study has found.
The misuse and overuse of antibiotics is the key driver of bugs mutating to become resistant to them, known as antimicrobial resistance. Experts have warned that safe and common surgeries may become hazardous if antimicrobial resistance makes it impossible to treat hospital-acquired infections.
Knee and hip joint replacements are on the rise due to an ageing population. While the antibiotic cefazolin is often given during these surgeries to prevent post-operative infections, a rise in bugs resistant to it has seen many hospitals combine it with another antibiotic called vancomycin, commonly used for golden staph.
Resistant strains of golden staph can be deadly and are often described as “superbugs” due to multiple antibiotics being ineffective against them.
Researchers led by Prof Trisha Peel, an infectious diseases clinician with Monash University, gave 4,239 joint replacement patients across 11 Australian hospitals cefazolin, either in combination with vancomycin or with a placebo.
Peel said post-operative infections affect up to 3% of joint replacement patients and “cause a lot of suffering”, with patients often needing repeat operations and sometimes dying. There is also a significant economic cost.
The researchers found vancomycin did not prevent infections among the patients. In an unexpected finding, 5.7% of knee joint replacement patients in the vancomycin group acquired an infection, compared with 3.7% of knee patients in the placebo group.
Peel said it is unclear why the added antibiotic increased infections in just knee surgery patients and that future studies will examine this.
But the research, published in the New England Journal of Medicine on Thursday, had definitively answered whether the combined treatment was effective with “no,” she said.
The inappropriate prescribing should stop, Peel said, with the national science agency CSIRO describing antimicrobial resistance as a “looming global health crisis”.
“If we don’t need to use an antibiotic, that’s an important thing to know, so that we’re conserving this important resource,” Peel said.
In rare cases, vancomycin can also trigger a serious, life-threatening allergic reaction known as anaphylaxis, adding to the importance of only using it when appropriate, she said.
Prof Jonathan Iredell, an infectious diseases physician and clinical microbiologist at the University of Sydney, said: “It is always important [to] ensure that common hospital protocols are the best they can possibly be.”
“Studies like this are essential to maintain the highest standards in modern health care,” he said.
