Antibiotic resistance is a type of drug resistance where a microorganism is able to survive exposure to an antibiotic. While a spontaneous or induced genetic mutation in bacteria may confer resistance to antimicrobial drugs, genes that confer resistance can be transferred between bacteria in a horizontal fashion by conjugation, transduction, or transformation. Thus, a gene for antibiotic resistance that evolves via natural selection may be shared. Evolutionary stress such as exposure to antibiotics then selects for the antibiotic resistant trait. Many antibiotic resistance genes reside on plasmids, facilitating their transfer. If a bacterium carries several resistance genes, it is called multidrug resistant (MDR) or, informally, a superbug or super bacterium.
Genes for resistance to antibiotics, like the antibiotics themselves, are ancient. However, the increasing prevalence of antibiotic-resistant bacterial infections seen in clinical practice stems from antibiotic use both within human medicine and veterinary medicine. Any use of antibiotics can increase selective pressure in a population of bacteria to allow the resistant bacteria to thrive and the susceptible bacteria to die off. As resistance towards antibiotics becomes more common, a greater need for alternative treatments arises. However, despite a push for new antibiotic therapies there has been a continued decline in the number of newly approved drugs. Antibiotic resistance therefore poses a significant problem.
Here are links to scientific reports about drug-resistant bacteria.
While most infection control measures are focused on hospitals, a new study points to the need for more targeted interventions to prevent the spread of drug-resistant bugs in nursing homes as community-associated strains of methicillin-resistant Staphylococcus aureus (CA-MRSA) are on the rise in these facilities. The study is published in the March issue of Infection Control and Hospital Epidemiology, the journal of the Society for Healthcare Epidemiology of America.
"Our research took place in China, but it reflects what's happening in many places around the world," said Tiedje, part of the research team led by Yong-Guan Zhu of the Chinese Academy of Sciences. "The World Organization for Animal Health and the U.S. Food and Drug Administration have been advocating for improved regulation of veterinary antibiotic use because those genes don't stay local."
Certain types of bacteria responsible for causing urinary tract infections (UTIs), the second-most-common infection in the United States, are becoming more difficult to treat with current antibiotics, according to new research from Extending the Cure (ETC), a project of the Center for Disease Dynamics, Economics & Policy. ETC released the research via its online ResistanceMap, an online tool created to track changes in antibiotic drug use and resistance. This year, ResistanceMap features analysis using ETC's Drug Resistance Index, a way for non-experts to track changes in antibiotic effectiveness.
Methicillin-resistant Staphylococcus aureus (MRSA) infection is caused by a strain of staph bacteria that's become resistant to the antibiotics commonly used to treat ordinary staph infections.
E. coli isolates from Arctic birds carried antimicrobial drug resistance determinants; among 17 antimicrobial drugs tested, resistance to 14 was detected. Resistance was observed in 8 isolates, 4 of which displayed resistance to >4 drugs (Table), and occurred most often to ampicillin, sulfamethoxazole, trimethoprim, chloramphenicol, and tetracycline. Two resistant isolates displayed isolated fosfomycin resistance with MIC values of 256 mg/L and 1,024 mg/L. No resistance to gentamicin, imipenem, or tigecycline was observed.
Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) doubled at academic medical centers in the U.S. between 2003 and 2008, according to a report published in the August issue of Infection Control and Hospital Epidemiology, the journal of the Society for Healthcare Epidemiology of America.