Identify the incorrect statement/s:

(A) Intestinal perforation and death may occur in severe cases of typhoid infection.
(B) Common cold is caused by Rhinoviruses.
(C) Lips and fingernails may turn grey to bluish colour in severe cases of pneumonia.
(D) Pneumonia is caused by Salmonella.
(E) Typhoid fever could be confirmed by Widal test.

Choose the correct answer from the options given below:

The correct option is (D) only.

Let us analyze each statement step-by-step to understand why statement (D) is the only incorrect statement among the given options:

Statement (A): "Intestinal perforation and death may occur in severe cases of typhoid infection."
This statement is correct. Typhoid fever is caused by the bacterium Salmonella typhi, which infects the small intestine. In severe untreated cases, it can lead to complications such as intestinal perforation (holes in the intestinal wall) and hemorrhages, which can be fatal.

Statement (B): "Common cold is caused by Rhinoviruses."
This statement is correct. The common cold is a viral infectious disease of the upper respiratory tract that is most commonly caused by Rhinoviruses.

Statement (C): "Lips and fingernails may turn grey to bluish colour in severe cases of pneumonia."
This statement is correct. Pneumonia is an infection that inflames the air sacs (alveoli) in one or both lungs. In severe cases, the body's oxygen levels drop significantly due to fluid accumulation in the lungs. This lack of oxygen (hypoxia) causes cyanosis, where the lips and fingernails turn a greyish to bluish color.

Statement (D): "Pneumonia is caused by Salmonella."
This statement is incorrect. Pneumonia is primarily caused by bacteria such as Streptococcus pneumoniae and Haemophilus influenzae, as well as various viruses and fungi. Salmonella is the genus of bacteria responsible for diseases like typhoid fever and food poisoning, not pneumonia.

Statement (E): "Typhoid fever could be confirmed by Widal test."
This statement is correct. The Widal test is a classic serological test used to diagnose and confirm typhoid fever by detecting antibodies against the O and H antigens of Salmonella typhi.

Since statement (D) is the only incorrect statement, the correct answer from the options is (D) only.