A big chunk of patients in India may no longer benefit from carbapenem, a powerful antibiotic administered mainly in ICU settings to treat pneumonia and septicemia, as they have developed antimicrobial resistance to it, an ICMR study has found.

The data analysis done between January 1 and December 31, 2021 pointed towards a sustained increase in drug-resistant pathogens, resulting in difficulty to treat certain infections with available medicines, senior Indian Council of Medical Research (ICMR) scientist Dr Kamini Walia, who led the study, said.

"Antibiotic resistance has the potential of taking the form of a pandemic in the near future if corrective measures are not taken immediately," she said.

The ICMR study report was released on Friday.

The data collected from the network has enabled compilation of drug resistance data on six pathogenic groups on antimicrobial resistance from the country.

Data collected from the network is used to track resistance trends and to better understand mechanisms of resistance in the key priority pathogens using genotypic characterisation and whole genome sequencing (WGS).

This is the fifth detailed report on antimicrobial resistance (AMR) trends and patterns from the country published by the ICMR. This year's report also carries hospital-acquired surveillance data.

According to the ICMR report, resistance to Imipenem, which is used to treat infections caused by bacteria E coli, has increased from 14 per cent in 2016 to 36 per cent in 2021.

The trend of decreasing susceptibility of bacteria to specific antibiotics was also observed with Klebsiella pneumoniae as it came down from 65 per cent in 2016 to 45 per cent in 2020 and 43 per cent in 2021.

The susceptibility term here is used to describe the vulnerability of the bacteria to the antibiotic.

Carbapenem resistance isolates of E coli and K pneumoniae are also resistant to other antimicrobials making it very challenging to treat carbapenem-resistant infections.

The resistance to broad-spectrum antibiotic carbapenem in respect to infections caused by Acinetobacter baumannii bacteria was recorded in 87.5 per cent of the patients who were part of the study, limiting the availability of treatment options, the ICMR report said.

Susceptibility of the same bacteria to minocycline is close to 50 per cent, making it the most susceptible antibiotic after colistin for Acinetobacter baumannii, it stated.

In Pseudomonas aeruginosa, another bacteria which causes infections in the blood, lungs (pneumonia), or other parts of the body after surgery, there is a consistent increase in susceptibility to all the major antipseudomonal drugs in the last few years, Dr Walia said.

"There is a need to strengthen and improve diagnostic labs to promote rational use of antibiotics. Antimicrobial prescriptions should be based on definitive diagnosis and not on presumptive diagnosis. Several broad-spectrum antimicrobials are being used for syndrome management," Dr Walia said.

"The resistance level is increasing to 5 to 10 per cent every year for broad-spectrum antimicrobials which are highly misused. With no new antimicrobials in the pipeline to treat drug-resistant infections, it is very important that we use judiciously what we have. There is also increasing levels of resistance of antifungals. Previously not many labs were doing fungal cultures and antifungal susceptibility.

"The ICMR AMR network has developed this over the last few years and now many labs are reporting antifungal susceptibility rates giving an idea on antifungal resistance rates. The use of antifungals was particularly high during the Covid pandemic," she said.

According to the ICMR report, in Staphylococcus aureus, which causes a wide variety of clinical diseases such as skin infections like abscesses and boils and sometimes pneumonia, endocarditis and osteomyelitis, susceptibility to erythromycin, clindamycin, ciprofloxacin, co-trimoxazole and high-level mupirocin was more evident in MSSA (Methicillin-Sensitive Staphylococcus Aureus) when compared to multi-drug resistant strains such as MRSA (Methicillin-Resistant Staphylococcus aureus).

MRSA rates are increasing each year from 2016 to 2021 (28.4 per cent to 42.6 per cent). Enterococci is another important pathogen which is quickly evolving and drug susceptibility has changed considerably in the last few years.

Several fungal pathogens like C. parapsilosis and C. glabrata are showing increasing resistance to commonly available antifungal medicines such as fluconazole, thus requiring close monitoring in the next few years.

Among diarrheal pathogens like Diarrheagenic E. coli, Shigella spp. and Salmonella that cause large proportions of diarrhoea cases in India, norfloxacin susceptibility was very poor. Empirical use of norfloxacin for the treatment of bacterial diarhhoea is strongly discouraged, Dr Walia said.

There has been no significant change in the overall antimicrobial susceptibility pattern of Salmonella Typhi or S Paratyphi A from India with the pattern remaining uniform across all the participating centres in the AMR network.

S. Typhi is 100 per cent susceptible to cephalosporins and azithromycin. Other drugs which retained good susceptibility for Salmonella Typhi or S. Paratyphi A are ampicillin, chloramphenicol and trimethoprim-sulfamethoxazole.