What is meant by the term 'broad spectrum antibiotics'? Explain.

Antibiotics that are effective against a wide range of gram-positive and gram-negative bacteria are known as broad spectrum antibiotics.
Chloramphenicol is a broad spectrum antibiotic. Its structure is as follows:
$O_2N-C_6H_4-CH(OH)-CH(NHCOCHCl_2)-CH_2OH$
It can be used for the treatment of typhoid,dysentery,acute fever,pneumonia,meningitis,and certain forms of urinary infections.
Two other broad spectrum antibiotics are vancomycin and ofloxacin.
Ampicillin and amoxicillin,which are synthetically modified from penicillin,are also broad spectrum antibiotics.