Question 3.3 from the second paper of 2014 and Question 17.3 from the second paper of 2010 both ask, "Why aren't my antibiotics working? Why won't this stubborn sepsis resolve?"
There could be numerous reasons. A 1972 issue of the BMJ has three different entries with the same title ("Causes of failure in antibiotic treatment") of which the first is an exploration by L.P. Garrod, and the others are letters to the editor by Cargill and Pollock. The Garrod paper is slightly dated but the issues remain current.
For rapid revision, thw whole thing can not be boiled down any better than the college answer to Question 3.3 from the second paper of 2014:
In greater detail, one can separate the issues into a series of heading:
Some examples:
For instance, you have destroyed the streptococci, but the streptococcal toxic shock syndrome has laid to waste your patient's organ systems, giving the overall impression of treatment failure.
Garrod, L. P. "Causes of failure in antibiotic treatment." BMJ 4.5838 (1972): 473-476.
Cargill, J. S. "Causes of failure in antibiotic treatment." BMJ 4.5843 (1972): 791-791.
Pollock, A. V. "Causes of failure in antibiotic treatment." BMJ 4.5843 (1972): 790-791.
García, Miguel Sánchez. "Early antibiotic treatment failure." International journal of antimicrobial agents 34 (2009): S14-S19.
Cunha, Burke A., and Antonio M. Ortega. "Antibiotic failure." The Medical clinics of North America 79.3 (1995): 663-672
Arancibia, Francisco, et al. "Antimicrobial treatment failures in patients with community-acquired pneumonia: causes and prognostic implications."American journal of respiratory and critical care medicine 162.1 (2000): 154-160.
Sanders, E., and P. F. Jurgensen. "Remediable causes of failure of" appropriate" antimicrobial therapy." Postgraduate medicine 50.5 (1971): 161. -Not available even as an abstract! Oh well, it was 1971.
Cox, G. Erika, J. D. Wilson, and Pamela Brown. "Protothecosis: a case of disseminated algal infection." The Lancet 304.7877 (1974): 379-382.
Stevens, Dennis L., et al. "The Eagle effect revisited: efficacy of clindamycin, erythromycin, and penicillin in the treatment of streptococcal myositis." Journal of Infectious Diseases 158.1 (1988): 23-28.