Cervical epithelial damage promotes Ureaplasma parvum ascending infection, intrauterine inflammation and preterm birth induction in mice

Around 40% of preterm births are attributed to ascending intrauterine infection, and Ureaplasma parvum (UP) is commonly isolated in these cases. Here we present a mouse model of ascending UP infection that resembles human disease, using vaginal inoculation combined with mild cervical injury induced by a common spermicide (Nonoxynol-9, as a surrogate for any mechanism of cervical epithelial damage). We measure bacterial load in a non-invasive manner using a luciferase-expressing UP strain, and post-mortem by qPCR and bacterial titration. Cervical exposure to Nonoxynol-9, 24 h pre-inoculation, facilitates intrauterine UP infection, upregulates pro-inflammatory cytokines, and increases preterm birth rates from 13 to 28%. Our results highlight the crucial role of the cervical epithelium as a barrier against ascending infection. In addition, we expect the mouse model will facilitate further research on the potential links between UP infection and preterm birth

In vitro efficacy of Imipenem-Relebactam and Cefepime-AAI101 against a global collection of ESBL-positive and carbapenemase-producing Enterobacteriaceae

Objectives: In vitro evaluation of the potential clinical efficacy of the novel β-lactam/β-lactamase-inhibitor combinations including imipenem-relebactam (IPM-REL) and cefepime-AAI101 (enmetazobactam) (FEP-AAI) against contemporary multidrug-resistant Enterobacteriaceae. Methods: Agar-based MIC screening against MDR-Enterobacteriaceae (n=264) was used to evaluate the in vitro efficacy of IPM-REL and FEP-AAI, to compare the results with established combinations, and to investigate alternative β-lactam partners for REL and AAI. The inhibition activities of REL, AAI and the comparators avibactam (AVI) and tazobactam, against isolated recombinant β-lactamases covering representatives from all four Ambler classes of β-lactamases were tested using a fluorescence-based assay. Results: Using recombinant proteins, all four inhibitors were highly active against the tested class A serine β-lactamases (SBLs); REL and AVI showed moderate activity against the Class C AmpC from P. aeruginosa and the Class D OXA-10/-48 SBLs, but outperformed tazobactam and AAI. All tested inhibitors lacked activity against Class B MBLs. In the presence of REL, IPM, but not AAI susceptibility increased against KPC-positive and OXA-48-positive isolates. Both aztreonam-AVI and ceftolozane-tazobactam were more efficacious than IPM-REL. In all the tested combinations, AAI was a more effective inhibitor of class A β-lactamases (ESBLs) than the established inhibitors. Conclusions: The results lead to the proposal of alternative combination therapies involving REL and AAI to potentiate the use of β-lactams against clinical Gram-negative isolates expressing a variety of β-lactamases. These results highlight the potential of novel combinations for combating strains not covered by existing therapies

Imitation of β-lactam binding enables broad-spectrum metallo-β-lactamase inhibitors

Carbapenems are vital antibiotics, but their efficacy is increasingly compromised by metallo-β-lactamases (MBLs). Here we report the discovery and optimization of potent broad-spectrum MBL inhibitors. A high-throughput screen for NDM-1 inhibitors identified indole-2-carboxylates (InCs) as potential β-lactamase stable β-lactam mimics. Subsequent structure–activity relationship studies revealed InCs as a new class of potent MBL inhibitor, active against all MBL classes of major clinical relevance. Crystallographic studies revealed a binding mode of the InCs to MBLs that, in some regards, mimics that predicted for intact carbapenems, including with respect to maintenance of the Zn(II)-bound hydroxyl, and in other regards mimics binding observed in MBL–carbapenem product complexes. InCs restore carbapenem activity against multiple drug-resistant Gram-negative bacteria and have a low frequency of resistance. InCs also have a good in vivo safety profile, and when combined with meropenem show a strong in vivo efficacy in peritonitis and thigh mouse infection models