ABSTRACT
Limited treatment options and multidrug-resistant (MDR)
Klebsiella pneumoniae
present a significant therapeutic challenge, underscoring the need for novel approaches. Drug repurposing is a promising tool for augmenting the activity of many antibiotics. This study aimed to identify novel synergistic drug combinations against
K. pneumoniae
based on drug repurposing. We used the clinically isolated GN 172867 MDR strain of
K. pneumoniae
to determine the reversal resistance activity of zidovudine (AZT). The combined effects of AZT and various antibiotics, including nitrofurantoin (NIT) and omadacycline (OMC), were examined using the checkerboard method, growth curves, and crystal violet assays to assess biofilms. An
in vitro
combination activity testing was carried out in 12 isolates of
K. pneumoniae. In vivo
murine urinary tract and lung infection models were used to evaluate the therapeutic effects of AZT + NIT and AZT + OMC, respectively. The fractional inhibitory concentration index and growth curve demonstrated that AZT synergized with NIT or OMC against
K. pneumoniae
strains. In addition, AZT + NIT inhibited biofilm formation and cleared mature biofilms.
In vivo
, compared with untreated GN 172867-infected mice, AZT + NIT and AZT + OMC treatment decreased colony counts in multiple tissues (
P
< 0.05) and pathological scores in the bladder and kidneys (
P
< 0.05) and increased the survival rate by 60% (
P
< 0.05). This study evaluated the combination of AZT and antibiotics to treat drug-resistant
K. pneumoniae
infections and found novel drug combinations for the treatment of acute urinary tract infections. These findings suggest that AZT may exert significant anti-resistance activity.