Nairobi Governor Evans Kidero has said Weston Hotel will be heavily penalised if it is established they served contaminated food.
Reports emerged on Friday that 50 people were hit with cholera while attending a health conference at the hotel, which is associated with Deputy President William Ruto.
The Health ministry strenuously denied that anyone had contracted the diarrhoeal disease.
Jackson Kioko, Director of Medical Services, said 24 rapid diagnostic tests had returned negative results for cholera.
Kidero said on Sunday that county health inspectors are conducting investigations at the hotel to establish whether the source of the outbreak.
"So far, the hotel management said the food served on the said day was obtained from outside. We are seriously following the matter and soon the truth shall be unveiled," he told journalists.
He said City Hall has also requested Weston management to provide medical records of all its staff to verify if they have undergone vaccination.
"Our minimal health standards is that those working in such facilities must undergo vaccination twice a year, that is why it is necessary to start from there and ascertain whether the hotel adheres to this regulation," he said.
Kidero said the officers had been informed of where the food was allegedly got from and were following to upturn every stone.
We take the issue of health and safety of our visitors seriously, and if we shall find out any contamination at the hotel, they will bear the maximum penalty, he said.
At least ten doctors who contracted the disease were discharged from Nairobi Hospital on Saturday and Sunday.
Two patients who were undergoing dialysis are still hospitalised.
The Star also established the 18 of 25 culture tests returned positive results for cholera.
The culture method most recommended test for diagnosis of cholera because it isolates and grows Vibrio cholerae bacteria.
Doctors said Weston Hotel, where the infection is suspected to have originated, show have been closed to manage the outbreak.
“There is a national guideline on cholera management. Weston should have been quarantined. Otherwise infections might continue and some people might go home and expose their families to infection,” said Dr Simon Kigondu, who has managed a similar outbreak in Isiolo.
But the hotel's general manager Michael Nzile told journalists that they had followed Health ministry procedures to contain the situation