some bacterial pathogens have developed antibiotic resistance. for example, a genetically distinct strain of staphylococcus aureus called mrsa is resistant to the commonly prescribed beta-lactam antibiotics. a 2013 report from the centers for disease control and prevention (cdc) estimated that in the united states, at least 2 million people get an antibiotic-resistant bacterial infection annually, with at least 23,000 of those patients dying from the infection. due to their indispensability in combating bacteria, new antibiotics are required for medical care. one target for new antimicrobial medications involves inhibiting dna methyltransferases, as these proteins control the levels of expression for other genes, such as those encoding virulence factors. fungi infection by fungal pathogens is treated with anti-fungal medication. athlete's foot, jock itch, and ringworm are fungal skin infections that are treated with topical anti-fungal medications like clotrimazole. infections involving the yeast species candida albicans cause oral thrush and vaginal yeast infections. these internal infections can either be treated with anti-fungal creams or with oral medication. common anti-fungal drugs for internal infections include the echinocandin family of drugs and fluconazole. algae while algae are commonly consider pathogens, the genus prototheca causes disease in humans. treatment for protothecosis is currently under investigation, and there is no consistency in clinical treatment. sexual interactions many pathogens are capable of sexual interaction. among pathogenic bacteria, sexual interaction occurs between cells of the same species by the process of genetic transformation. transformation involves the transfer of dna from a donor cell to a recipient cell and the integration of the donor dna into the recipient genome through genetic recombination. the bacterial pathogens helicobacter pylori, haemophilus influenzae, legionella pneumophila, neisseria gonorrhoeae, and streptococcus pneumoniae frequently undergo transformation to modify their genome for additional traits and evasion of host immune cells. eukaryotic pathogens are often capable of sexual interaction by a process involving meiosis and fertilization. meiosis involves the intimate pairing of homologous chromosomes and recombination between them. examples of eukaryotic pathogens capable of sex include the protozoan parasites plasmodium falciparum, toxoplasma gondii, trypanosoma brucei, giardia intestinalis, and the fungi aspergillus fumigatus, candida albicans and cryptococcus neoformans. viruses may also undergo sexual interaction when two or more viral genomes enter the same host cell. this process involves pairing of homologous genomes and recombination between them by a process referred to as multiplicity reactivation. the herpes simplex virus, human immunodeficiency virus, and vaccinia virus undergo this form of sexual interaction. these processes of sexual recombination between homologous genomes supports repairs to genetic damage caused by environmental stressors and host immune systems.