Many diseases may be cured by using antibiotics. However, the success of some antibiotics against puerperal fever \(родильная горячка\) has diminished in recent years. What is the reason for this?

• Bacteria become resistant to antibiotics.
• The need for these antibiotics has been reduced because public health conditions have improved considerably in recent years.
• Once produced, antibiotics gradually lose their activity.
• These antibiotics only help against puerperal fever, but not against other diseases.