There are people working on new antibiotics, both in the sense of totally new antibiotic classes,and in synthetically tweaking existing ones. Not enough people working on them though, and not enough pharmaceutical companies.
New drugs on average take anywhere between around 10-20 years from laboratory proof of efficacy through to being available on prescription.
The implications for medical treatments would be profound, ranging from serious infections of routine surgery cases through to decreased efficiency in treating cancers and other such neoplasms, since such aggressive treatment needs antibiotic support for the immune suppression such treatment causes.
STDs could also run rampant again - there are now antibiotic resistant strains of gonorrhea, for instance.
So cleanliness, isolation wards all become much, much more important.
Can we combat strains of infection with the current antibiotics? Yes, but more and more of the common infectious agents are developing strains which are resistant to antibiotics.
We are still relatively fortunate in that those bacteria that have developed antibiotic resistant strains are usually only resistant to 1 or 2 of the different classes of antibiotics, so we can usually find an alternative treatment - but the nightmare scenario would be a strain of gram-negative bacteria multiply -resistant to all the major classes of antibiotics, including the current class of last resort, the carbapenems.
Casual use of antibiotics in agriculture, the over-prescription of antibiotics by medical professionals, and the publics desire to receive a pill to cure what are usually transient infections that will clear up of their own accord within a few days to a week, regardless of the fact that antibiotics can be of no use whatsoever in treating viral illnesses, such as flu, for instance.....
Pharmaceutical companies require encouragement from governments to move the provision of new antibiotics much higher up the development agenda as a matter of urgency, otherwise we will find ourselves back in a medical health situation similar to our ancestors around the turn of the century...