Ever since penicillin-resistant bacteria emerged just a few years after the discovery of the antibiotic, the science community has been aware that the struggle to treat bacterial infections will not be overcome simply through the use of a silver bullet. Indeed, a number of other types of antibiotics have since emerged, but unfortunately these too have shown to be susceptible to the development of resistance.
So let's briefly discuss what antibiotics are. Though bacteria and human cellular mechanisms have many parallels, there are also many differences, and it is essentially variances in these mechanistic/genetic characteristics which can be targeted to inhibit bacterial growth. Antibiotics are designed to exploit these differences by either impeding bacterial growth (bacteriostatic) or by killing bacteria (bactericidal).
Unlike us however, bacteria evolve very quickly and develop resistance to such drugs by "mating", mutations, or simply, natural selection. This poses a serious problem, particularly when bacteria become resistant to multiple antibiotics. Other types of medication, such as anti-cholesterol drugs, usually become outdated because of newer and improved drugs and not due to decreased function (ie resistance); however, even then, this is not always the case (eg. aspirins has been effectively used and described by Hippocrates). Though this places a constant pressure for the creation of newer and better antibiotics, the chance for the development of resistance makes investing in new antibiotics a risky business.
A recent report by the World Health Organization (WHO) exemplifies the pervasive nature of the antibiotic resistance problem by issuing a warning of the spread of a dangerous and multiresistant strain of Neisseria gonorrhea over multiple continents. The infection is usually transmitted sexually and thus there is some recourse to prevention (eg. use of barrier contraceptives). The emergence of this issue does however underscore the need to reaffirm our commitment to the diligent use of antibiotics and improving efforts to prevent the formation of resistance. Because if we are not careful, we may find ourselves in a position where the increased emergence of antibiotics resistance outpaces our ability to innovate new antibiotics.