Table 3. Representative quotations from Theme 2 reflecting ‘Psychological Capability’ of the COM-B model.

Theme 2: Prescriber autonomy overrules guideline compliance.
Subtheme	TDF Domains	Illustrative quotes	Barrier or enabler?
Guideline knowledge and awareness of limitations	• Knowledge • Memory, attention and decision processes • Behavioural regulation	“No, because every patient is different. So, guidelines are guidelines. They’re not rules. So, they can be helpful, and they may, you know, stop you from giving them for five days. But, it’s not going to stop you from worrying. Especially, contamination. It’s not going to stop me.” (F4, public colorectal surgeon)	Barrier
		“I think this generation are very quick to refer to guidelines and look things up. I think they’re very good at accessing them. The sort of stuff that we used to carry around in our heads, it’s just not necessary anymore because you just have a look at the antibiotic guidelines and it’s there for you.” (F4, public colorectal surgeon)	Enabler
		“Even though there might be recognised guidelines, many surgeons have their own preferences; which they will override, and they might say, ‘Yeah, I know there’s no evidence for antibiotics, but I want them anyway.’ Or, ‘I know the guideline says use cefazolin or whatever, but I like ceftriaxone.’” (F3, private anaesthetist)	Barrier
		“I think the assumption for most of the surgeons would be that their practice that is deviating from these guidelines, does not deviate because they’re unaware of the guidelines. And us (pharmacists), just letting them know that they exist isn’t going to solve the problem… The education of the surgeon is not necessarily the gap.” (F3, private pharmacist)
Competition as a means to regulate behaviour	• Behavioural regulation	“So, where you feed that (audit data)… I mean, people in medicine, particularly doctors, are very competitive. So, you know, people don’t like to be down at the bottom of the pack… And, they want to do what’s best overall. So, if you show that they’re not meeting the guidelines, then they will work to get the results.” (F3, private anaesthetist)	Enabler
		“Neurosurgeons are very competitive. If you can show a unit that their infection rate is crap, they’ll try and do something about it”. (F6, public neurosurgeon)
		“If you can benchmark and compare them (surgeons) to other people, that’s another way (to change practice).” (F12, public pharmacist)