A lawmaker and Chinese medicine veteran said on Wednesday there is no need for public panic or people to stop receiving all their ongoing acupuncture treatments due to fears of a serious infection.

The reassurance came after the Centre for Health Protection (CHP) said on Tuesday it was investigating the case of a 47-year-old man who had to have his left lower leg amputated after developing a Group A Streptococcal infection, also known as a "flesh-eating disease", following acupuncture treatments.

Speaking on an RTHK programme, Election Committee lawmaker Chan Wing-kwong, who's also a Chinese medicine practitioner, noted that the incident might be a "one-off case".

"I believe everyone knows that in Hong Kong, perhaps more than several thousand people receive acupuncture treatments every day," Chan said.

"According to the information I have read, it is the first time such an incident has occurred in Hong Kong."

"And if I look for such cases for the world, there won't be more than 20.

"This might not just be caused by acupuncture.

"Before the incident is fully understood and investigated, any comments concerning the practitioners or the patients might not be fair."

Chan urged residents who found acupuncture treatments to be helpful to continue with their treatments, noting other patients who received such treatments from the practitioners at the clinics involved did not report such infections.

He added that one's physical condition might also play a role in susceptibility to infections.

For his part, University of Hong Kong microbiologist Ho Pak-leung noted that the incident might be related to improper handling of needles during acupuncture treatments.

Ho also noted that it is possible for bacteria to be transmitted to a disinfected patch of skin on the patient during the needle injection process if someone nearby sneezed or coughed.

In a statement, the CHP said the man had sought treatment after spraining his back while lifting heavy projects on April 6 and subsequently experiencing pain in his left hip as well as numbness in his left leg and foot.

He received acupuncture treatments from registered Chinese medical practitioners at two clinics in Sheung Wan and Causeway Bay from April 7 to 10 before developing a fever and pains in his left thigh on April 11.

The man sought treatment at a private hospital and was diagnosed with septic shock and necrotising fasciitis, commonly known as “flesh-eating disease”, and was then transferred to Queen Mary Hospital where he underwent a left lower limb amputation.

After reviewing samples at the clinics, the centre said investigators suspected that the case might have been caused by improper infection control procedures by practitioners when performing acupuncture, as one of the environmental samples at the Causeway Bay clinic tested positive for the infection the man developed.

The centre added that the man, who had underlying illnesses, remains hospitalised in a stable condition.