There was “huge uncertainty” during the first wave of coronavirus and there were not many treatment options for those in critical care.
But, experts have claimed in a study, it is now known that bacterial co-infection is uncommon in community-acquired Covid patients.
They said that giving antibiotics to Covid-19 patients who do not have a bacterial co-infection risks worsening global antimicrobial resistance.
New analysis published in the journal The Lancet Microbe shows that between February and June last year, 85 per cent of Covid patients received one or more antibiotics during their hospital stay.
Meanwhile 37 per cent were prescribed the drugs prior to admission.
The scientists recommended that antibiotic use should be more evidence-based and medics should restrict prescribing these drugs unless tests confirm a bacterial infection.
Study author Dr Antonia Ho, of the MRC-University of Glasgow Centre for Virus Research, said: “Our findings are in no way a criticism of the NHS clinicians.
“During the first wave, there was huge uncertainty as this is a new disease (and) patients were very sick – a lot of patients were in critical care.
“We did not have very many options in terms of effective treatments and, (based on) how sick patients were, I think it was a sensible thing to do (prescribe antibiotics) at the time.”
She added: “However, we now know that bacterial co-infection is uncommon in patients with community-acquired Covid-19.
“Since antimicrobial resistance remains one of the biggest public health challenges of our time, measures to combat it are essential to help ensure that these life-saving medicines remain an effective treatment for infection in years to come.”
According to the World Health Organisation (WHO), antibiotic resistance is one of the biggest threats to global health, with an estimated 700,000 deaths worldwide every year.
Antibiotics are medicines used to treat some types of bacterial infections and do not work on viral diseases, such as Covid-19.
As part of the Isaric (International Severe Acute Respiratory and emerging Infections Consortium) study, scientists from the Universities of Glasgow, Edinburgh and Liverpool and Imperial College London looked at data from nearly 49,000 Covid-19 patients admitted to 260 hospitals in England, Scotland and Wales.
Of 8,649 patients with recorded blood tests, bacterial infections were detected in 1,107 of them.
By contrast, the researchers said, bacterial co-infections are far more common with severe influenza, occurring in nearly a quarter of patients.
Among coronavirus patients with confirmed bacterial infections, 71 per cent were found to be secondary infections, meaning these were acquired more than 48 hours after hospital admission.
The team found that broad-spectrum antibiotics – those active against a very wide range of bacteria – were used frequently, accounting for 3.8 per cent of all prescriptions.
Dr Clark Russell, of the University of Edinburgh Centre for Inflammation Research, said antimicrobial usage in Covid-19 hospital patients was “very high” during the first wave but there is evidence of a reduction towards the end of that period, with less usage in May compared with March and April.
But he added: “Overall, we have identified patterns of usage that could accelerate the emergence of antimicrobial resistant bacteria.
“This is especially concerning considering the scale of the problem with such large numbers of people hospitalised with Covid in the UK and around the world.”
Dr Russell said: “Prioritising and incorporating existing antimicrobial stewardship principles into care plans could help to prevent a rise of drug-resistant infections becoming a longer-term sequela of the pandemic.”
Current UK guidelines advise against antibiotic use when the respiratory tract infection is thought to be due to Covid-19 without specific evidence of bacterial infection.
