Which bacteria are harder to kill?

• A. Fungi
• B. Gram-negative
• C. Gram-positive
• D. Viruses

Answer: (B)

Think about how the bacterial cell envelope affects how hard it is for agents to reach and disrupt the cell. Gram-negative bacteria have an outer membrane outside a thin peptidoglycan layer. That outer membrane acts like a shield, limiting the entry of many antibiotics and disinfectants. Porin channels and efflux pumps further control and reduce how much drug can accumulate inside, and many Gram-negatives produce enzymes that inactivate drugs. All of this adds up to a higher level of intrinsic resistance, making them harder to kill than Gram-positive bacteria, which lack that outer membrane and have a thicker but more penetrable peptidoglycan wall. Fungi and viruses aren’t bacteria, and their vulnerabilities differ, but within bacteria, those with the outer membrane tend to be more resistant.