Antibiotic resistance tests: Bacteria are streaked on dishes with white disks, each impregnated with a different antibiotic. Clear rings, such as those on the left, show that bacteria have not grown—indicating that these bacteria are not resistant. The bacteria on the right are fully resistant to all but two of the seven antibiotics tested.|alt=Two petri dishes with antibiotic resistance tests<unk>  <unk>  occurs when microbes evolve mechanisms that protect them from the effects of<unk> s. Antibiotic resistance is a subset of<unk> , that applies specifically to bacteria that become resistant to antibiotics. Infections due to<unk>  cause millions of deaths each year. Infections caused by resistant microbes are more difficult to treat, requiring higher doses of<unk>  drugs, or alternative medications which may prove more toxic. These approaches may also be more expensive. Microbes resistant to multiple<unk> s are called multidrug resistant (MDR). All classes of microbes can evolve resistance. Fungi evolve antifungal resistance. Viruses evolve antiviral resistance. Protozoa evolve antiprotozoal resistance, and bacteria evolve antibiotic resistance. Those bacteria that are considered extensively drug resistant (XDR) or totally drug-resistant (TDR) are sometimes called "superbugs". Resistance in bacteria can arise naturally by genetic mutation, or by one species acquiring resistance from another. Resistance can appear spontaneously because of random mutations. However, extended use of<unk> s appears to encourage selection for mutations which can render<unk> s ineffective. The prevention of antibiotic misuse, which can lead to antibiotic resistance, includes taking antibiotics only when prescribed. Narrow-spectrum antibiotics are preferred over broad-spectrum antibiotics when possible, as effectively and accurately targeting specific organisms is less likely to cause resistance, as well as side effects. For people who take these medications at home, education about proper use is essential. Health care providers can minimize spread of resistant infections by use of proper sanitation and hygiene, including handwashing and disinfecting between patients, and should encourage the same of the patient, visitors, and family members. Rising drug resistance is caused mainly by use of<unk> s in humans and other animals, and spread of resistant strains between the two. Growing resistance has also been linked to releasing inadequately treated effluents from the pharmaceutical industry, especially in countries where bulk drugs are manufactured. Antibiotics increase selective pressure in bacterial populations, causing vulnerable bacteria to die; this increases the percentage of resistant bacteria which continue growing. Even at very low levels of antibiotic, resistant bacteria can have a growth advantage and grow faster than vulnerable bacteria. As resistance to antibiotics becomes more common there is greater need for alternative treatments. Calls for new antibiotic therapies have been issued, but new drug development is becoming rarer.<unk>  is increasing globally due to increased prescription and dispensing of antibiotic drugs in developing countries. Estimates are that 700,000 to several million deaths result per year and continues to pose a major public health threat worldwide. Each year in the United States, at least 2.8 million people become infected with bacteria that are resistant to antibiotics and at least 35,000 people die and US$55 billion in increased health care costs and lost productivity. According to World Health Organization (WHO) estimates, 350 million deaths could be caused by<unk>  by 2050. By then, the yearly death toll will be 10 million, according to a United Nations report. There are public calls for global collective action to address the threat that include proposals for international treaties on<unk> . Worldwide antibiotic resistance is not completely identified, but poorer countries with weaker healthcare systems are more affected. During the COVID-19 pandemic, action against<unk>  slowed due to scientists focusing more on SARS-CoV-2 research.
Antimicrobial resistance
Drug resistance
Antibiotic synergy
Multiple drug resistance
Opportunistic infection
Vaccine resistance
Immunocompetence
Tolerogenic therapy