Pharmaceutical composition for inhibiting CRE and application

Abstract

The invention discloses a pharmaceutical composition for inhibiting CRE and application, and relates to the technical field of drug research and development, and the key points of the technical scheme are as follows: the effect of aztreonam combined with four beta-lactamase inhibitors (avibactam, clavulanic acid, tazobactam and sulbactam) on 77 CRE isolates in Shenzhen children hospitals is evaluated. It is found that most of CRE isolates, resistant to aztreonam, in CRE isolates collected in Shenzhen children hospitals carry MBL and other beta-lactamase genes at the same time. And aztreonam / avibactam has good antibacterial activity on all the tested strains. For isolates which carry MBL genes but do not have AmpC enzyme coding genes, aztreonam / clavulanic acid can be used as a more economical and potential combination therapy regimen than aztreonam / avibactam, but is not suitable for CRE isolates carrying AmpC enzyme genes.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of drug research and development, and more particularly to a drug composition for inhibiting CRE and application thereof. BACKGROUND

[0002] The Carbapenem-Resistant Enterobacterales (CRE) is listed as a key priority group in the World Health Organization's updated List of Priority Pathogens in 2024. Carbapenems were once the last line of defense for treating Enterobacterales infections. However, due to the extensive use of carbapenems in clinical practice, the detection rate of CRE has been increasing year by year.

[0003] It is reported that the mortality rate of patients with CRE bloodstream infections is as high as 32.9%. Traditional antibiotics with lower resistance rates in CRE include amikacin, polymyxin and tigecycline. In 2023, the Clinical and Laboratory Standards Institute (CLSI) lowered the breakpoint of amikacin for treating Enterobacterales and recommended that amikacin should be used in combination with other antibiotics for infections other than uncomplicated cystitis and pyelonephritis. Polymyxin drugs have serious nephrotoxicity and poor clinical efficacy, while tigecycline has a low free drug concentration in blood and poor efficacy in treating bloodstream infections. In contrast, new β-lactamase inhibitor combinations have good clinical application value. Among them, ceftazidime / avibactam has a higher clinical treatment success rate for CRE than polymyxin. Amikacin / avibactam has good antibacterial activity against CRE strains producing metallo-β-lactamases (MBL), and has good antibacterial activity against ≥98.9% of CRE strains resistant to ceftazidime / avibactam, meropenem / verubactam and imipenem / relabactam.

[0004] Understanding the resistance mechanisms of carbapenems (CRE) is crucial for treating CRE infections and developing new antibacterial agents. The resistance mechanisms of CRE to β-lactam antibiotics mainly involve carbapenemase production, high AmpC production, lack of membrane porin binding, or high expression of efflux pumps. The type of carbapenemase is closely related to the choice of antibacterial treatment regimen. In 2019, a novel β-lactamase inhibitor combination, ceftazidime / avibactam, was launched in China and approved for pediatric use in 2020. Studies have shown that avibactam has good antibacterial activity against carbapenemases including KPC-2 and OXA-48, but is ineffective against some KPC variants and MBL. Previous studies have shown that in China, the production rate of MBL in carbapenemase-producing Enterobacteriaceae (CPE) isolates from children is >50%. Because MBL cannot hydrolyze aztreonam, and because avibactam can inhibit ESBLs and AmpC enzymes produced by most CRE isolates, the IDSA guidelines recommend that, except for urinary tract infections, the first-line treatment for infections caused by MBL-producing CRE strains should be aztreonam in combination with ceftazidime / avibactam or cefoperazone monotherapy. However, since cefoperazone is not yet available in the Chinese market, only aztreonam in combination with ceftazidime / avibactam can be considered the first-line treatment. Furthermore, reports indicate that cirA mutations, PBP3 insertions, and NDM production can all lead to cefoperazone resistance, while aztreonam / avibactam can remain effective.

[0005] As early as 2018, it was reported that the combined use of aztreonam and clavulanic acid was a good indicator for detecting ESBL production in MBL-producing strains. However, at that time, this treatment was only reported as a means of detecting ESBL resistance mechanisms. Furthermore, Stenotrophomonas maltophilia naturally produces MBL. Other studies have reported that the combined use of aztreonam with clavulanic acid or avibactam also has good antibacterial activity against Stenotrophomonas maltophilia, with the earliest report published in 1991. Similar reports have been made regarding MBL-producing Enterobacteriaceae or Pseudomonas aeruginosa, but these studies only used the Etest band stacking method or time-kill curve method, and the number of isolated samples tested was relatively small, lacking representativeness. Summary of the Invention

[0006] The purpose of this invention is to provide a pharmaceutical composition and application for inhibiting CRE, by comparing the antibacterial activity of aztreonam combined with avibactam, clavulanic acid, sulbactam or tazobactam against CRE in children producing different β-lactamases; and to find a more economical combination therapy regimen than aztreonam combined with avibactam.

[0007] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a pharmaceutical composition for inhibiting CRE, wherein the active ingredients of the pharmaceutical composition are composed of aztreonam and clavulanic acid.

[0008] The present invention is further configured such that the pharmaceutical composition is suitable for isolates carrying the MBL gene but lacking the AmpC enzyme gene.

[0009] The present invention is further configured such that the concentration ratio of aztreonam to clavulanic acid in the pharmaceutical composition is 5:1.

[0010] The present invention is further configured such that clavulanic acid in the pharmaceutical composition is preferably used in combination with aztreonam at a fixed concentration of 4 µg / mL.

[0011] The present invention is further configured such that when the pharmaceutical composition is used in isolates carrying the MBL gene but without the AmpC enzyme gene, the MIC50 and MIC90 values ​​at a clavulanic acid concentration of 4 µg / mL are ≤0.12 µg / mL and 1 µg / mL, respectively.

[0012] The present invention is further configured such that: the pharmaceutical composition comprises the active ingredients aztreonam, clavulanic acid, and pharmaceutically acceptable excipients, wherein the pharmaceutically acceptable excipients are selected from at least one of pharmaceutically acceptable solvents, solubilizers, cosolvents, emulsifiers, osmotic pressure regulators, stabilizers, suspending agents, coating materials, anti-adhesives, binding agents, penetration enhancers, pH adjusters, buffers, surfactants, absorbents, diluents, filter aids, and sustained-release materials.

[0013] The present invention further provides the use of the above-described pharmaceutical composition in inhibiting CRE.

[0014] The present invention further provides the use of the above-mentioned pharmaceutical composition in the preparation of a clinical anti-infective drug.

[0015] In summary, this invention offers the following advantages: the combination of aztreonam and clavulanic acid, both β-lactamase inhibitors, has a very low MIC (microinhibitory response rate), and exhibits synergistic effects in vitro against some CRE strains carrying the MBL gene but not the AmpC enzyme gene. For infections caused by CRE strains with resistance mechanisms to these antimicrobial drugs, aztreonam combined with clavulanic acid may be a potential alternative to aztreonam / avibactam. Its advantages include reducing the economic burden on patients while decreasing the use of aztreonam / avibactam, thus delaying the development of aztreonam / avibactam resistance. Attached Figure Description

[0016] Figure 1 This invention describes the combined effects of aztreonam and four β-lactamase inhibitors on CRE isolates. AA: aztreonam combined with avibactam; AC: aztreonam combined with clavulanic acid; AS: aztreonam combined with sulbactam; AT: aztreonam combined with tazobactam. No AmpC: Enterobacteriaceae that do not carry the AmpC enzyme gene; Non-CPE: Enterobacteriaceae that do not produce carbapenemase.

[0017] Figure 2 This invention presents the MIC distributions of aztreonam and four β-lactamase inhibitors at different concentration ratios on CRE isolates in embodiments of the present invention. A: aztreonam combined with avibactam; B: aztreonam combined with clavulanic acid; C: aztreonam combined with sulbactam; D: aztreonam combined with tazobactam.

[0018] Figure 3 This invention presents the relationship between the average log10 CFU / mL of aztreonam (ATM) alone and in combination with 4 µg / mL of avibactam, clavulanic acid, sulbactam, or tazobactam against three strains of Klebsiella pneumoniae over time. The curves represent the average concentration from three experiments.

[0019] A: kpn-6 (ST307; IMP-38, TEM-1, SHV-28, CTX-M-3; ATM only MIC: 64µg / mL); B: kpn-12 (ST11; KPC-2, TEM-1, SHV-11, CTX-M-65; only ATM MIC>128µg / mL); C: kpn-47 (ST273; NDM-5, TEM-1, SHV-11, CTX-M-3; ATM only MIC: 128µg / mL). Detailed Implementation

[0020] The following is in conjunction with the appendix Figures 1-3 The present invention will be described in further detail below.

[0021] Definition: CRE is defined as Enterobacteriaceae that are resistant to any carbapenem, with Proteus, Morganella, and Providencia being defined as resistant to other carbapenems except imipenem.

[0022] Example: A pharmaceutical composition for inhibiting CRE and its application 1. Strain collection We collected aztreonam-resistant cerebral refractory (CRE) samples from clinical departments of Shenzhen Children's Hospital between 2014 and 2021, removed duplicate isolates from the same child, and identified the isolates by bacteria.

[0023] 2. Drug sensitivity test Antimicrobial susceptibility testing was performed using the microbroth dilution method to determine the minimum inhibitory concentration (MIC) of various antibiotics against CRE. The microbroth dilution susceptibility test plates used in this test were purchased from Thermo Fisher Scientific; avibactam standard was purchased from Dalian Meilun Pharmaceutical Co., Ltd.; and aztreonam, clavulanic acid, sulbactam, and tazobactam standard bacteria were purchased from the National Institutes for Food and Drug Control (NIFDC). The corresponding solvents and diluents for the antimicrobial standards were purchased from Sinopharm Reagent Co., Ltd. Antimicrobial susceptibility test results were interpreted according to CLSI breakpoints, and the results for tigecycline and aztreonam / avibactam were interpreted using the breakpoint standards of the U.S. Food and Drug Administration (FDA); the results for cefoperazone / sulbactam were interpreted according to the cefoperazone breakpoint standards.

[0024] The synergistic effect of aztreonam in combination with avibactam, clavulanic acid, sulbactam, or tazobactam for the treatment of aztreonam-resistant chronic renal disease (CRE) was evaluated using the microbroth dilution checkerboard method and time-based sterilization curve assays; the test methods were based on the American Manual of Clinical Microbiology Procedures. The microbroth dilution checkerboard method and time-based sterilization curve assays were performed in cationic-regulated Mueller–Hinton broth (CAMHB) under ambient air conditions.

[0025] In the microbroth dilution checkerboard method, aztreonam was serially diluted horizontally on a 12×12 microtiter plate to obtain final concentrations ranging from 0.12 μg / mL to 128 μg / mL. Avibactam, clavulanic acid, sulbactam, or tazobactam were also diluted vertically to the same concentration range. The assay was repeated three times to assess the synergistic effect between aztreonam and each β-lactamase inhibitor to ensure reproducibility of results.

[0026] For the time-killing curve experiment, bacterial growth was evaluated three times under the following conditions: drug-free growth control, aztreonam alone, and aztreonam in combination with 4 μg / mL avibactam, clavulanic acid, sulbactam, or tazobactam. After inoculation, culture medium was collected at 0, 2, 4, 8, 10, and 24 hours, and colonies were counted on blood agar to determine viable cell concentration.

[0027] 3. Quality control strains Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 29213, Escherichia coli ATCC 25922 and ATCC 35218, Pseudomonas aeruginosa ATCC 27853, and Klebsiella pneumoniae ATCC 700603 were used as quality control strains. Each time an antimicrobial susceptibility test was performed, the corresponding quality control strains were used for quality control testing to ensure the reliability of the antimicrobial susceptibility test results.

[0028] 4. Statistical Analysis Statistical analysis of antimicrobial susceptibility test results was performed using WHONET 5.6 software. GraphPad Prism 9.5.1 software was used to generate graphs. The combined effect of aztreonam with four β-lactamase inhibitors was determined by calculating the fractional inhibitory concentration (FIC) index. FIC = (MIC of aztreonam in combination with other drugs / MIC of aztreonam alone) + (MIC of β-lactamase inhibitor in combination with other drugs / MIC of β-lactamase inhibitor alone). FIC ≤ 0.5 indicated synergistic effect, FIC > 0.5 - 1 indicated additive effect, FIC = 1 - 2 indicated no effect, and FIC > 2 indicated antagonistic effect.

[0029] 5. Results 5.1 Bacterial distribution and antimicrobial susceptibility results To determine the combined effects of aztreonam with different enzyme inhibitors, cefuroxime strains resistant to aztreonam were selected, and their resistance was tested using a microbroth dilution method. From 2014 to 2021, Shenzhen Children's Hospital isolated 77 aztreonam-resistant cefuroxime strains, including *Klebsiella pneumoniae* (n=42, 54.5%), *Escherichia coli* (n=15, 19.5%), *Klebsiella pneumoniae* (n=10, 13%), *Enterobacter cloacae* (n=8, 10.4%), and one strain each of *Citrobacter freundii* and *Proteus vulgaris*. Except for amikacin, polymyxin B, and tigecycline, these cefuroxime strains showed resistance rates >50% to all tested antibiotics. The MIC50 and MIC90 values ​​of amoxicillin / clavulanic acid, cefoperazone / sulbactam, ceftazidime / avibactam, piperacillin / tazobactam, cefazolin, cefuroxime, ceftazidime, ceftriaxone, cefepime, and trimethoprim / sulfamethoxazole were all >32 µg / mL. The resistance rate of ceftazidime / avibactam was 55.8%. The MIC50 and MIC90 values ​​of aztreonam / avibactam were 0.25 µg / mL and 2 µg / mL, respectively. Klebsiella pneumoniae and Escherichia coli showed higher resistance rates to cefepime, meropenem, amikacin, ciprofloxacin, and levofloxacin than Enterobacter cloacae complex and Klebsiella pneumoniae, but lower resistance rates to imipenem, trimethoprim / sulfamethoxazole, and polymyxin B (Table 1).

[0030] Table 1. Drug susceptibility test results of 77 aztreonam-resistant CRE strains.

[0031]

[0032] 5.2 Distribution of β-lactamase genes and results of checkerboard dilution method To investigate the synergistic effects of aztreonam combined with different enzyme inhibitors against CRE strains with varying resistance mechanisms, whole-genome sequencing was used to determine the resistance mechanisms of these strains, and the synergistic effect was tested using a checkerboard dilution method. Among the 77 CRE isolates resistant to aztreonam, 57.1% carried the MBL gene, while the KPC gene was detected only in *Klebsiella pneumoniae* (11.9%). The detection rates of the ESBL gene in *Klebsiella pneumoniae* and *Escherichia coli* were 90.5% and 93.3%, respectively, higher than those in *Klebsiella pneumoniae* (30%) and *Enterobacter cloacae* complex (12.5%). The detection rates of the AmpC enzyme gene in *Klebsiella pneumoniae* and *Escherichia coli* were 11.9% and 26.7%, respectively, lower than those in *Klebsiella pneumoniae* (100%) and *Enterobacter cloacae* complex (87.5%). The checkerboard dilution results showed that aztreonam and avibactam had a synergistic effect in all 77 CRE isolates. The most common combined effects of aztreonam with clavulanic acid, sulbactam, or tazobactam were synergistic (50.6%), unrelated (68.8%), and synergistic (40.2%), respectively. The synergistic effect rates of aztreonam combined with clavulanic acid against Klebsiella pneumoniae and Escherichia coli were 52.3% and 80%, respectively, higher than those against Klebsiella pneumoniae (10%) and Enterobacter cloacae complex (25%). The antagonistic effects against Klebsiella pneumoniae and Escherichia coli were 2.3% and 0%, respectively, lower than those against Klebsiella pneumoniae (30%) and Enterobacter cloacae complex (12.5%). The synergistic effect of aztreonam combined with tazobactam on various isolates was similar to that of aztreonam combined with clavulanic acid, but the proportion of synergistic effect was slightly lower. The synergistic effect of aztreonam combined with sulbactam on Klebsiella pneumoniae, Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae complex was mostly not significant. The distribution of β-lactamase genes in each isolate and the results of combined drug susceptibility testing using the checkerboard dilution method are shown in Tables 2, 3, and 4.

[0033] Table 2. Distribution of β-lactamase genes and results of checkerboard dilution combined with drug susceptibility testing in 77 aztreonam-resistant CRE strains.

[0034]

[0035]

[0036]

[0037]

[0038]

[0039] Table 4. Resistance of CREs carrying different β-lactamase genes to aztreonam combined with four different concentrations of β-lactamase inhibitors.

[0040]

[0041]

[0042] Individual analyses of different resistance mechanisms showed that the combination of aztreonam and avibactam had a synergistic effect on all tested strains. In CRE isolates carrying the KPC gene, the combination of aztreonam with clavulanic acid or tazobactam had additive effects on 2 / 5 and 1 / 5 of the isolates, respectively. In CRE isolates carrying the MBL gene but not the AmpC enzyme gene, the combination of aztreonam and clavulanic acid had a synergistic effect on 26 / 27 isolates, followed by the combination of aztreonam and tazobactam, which had a synergistic effect on 12 / 27 isolates. In CRE isolates carrying both the MBL and AmpC enzyme genes, the combination of aztreonam and clavulanic acid had a synergistic effect on 6 / 16 isolates and an antagonistic effect on 4 / 16 isolates. In genomes lacking carbapenemase and AmpC enzyme genes, aztreonam, in combination with clavulanic acid and tazobactam, showed synergistic effects in 6 / 18 and 12 / 18 isolates, respectively, while in AmpC enzyme gene-carrying genomes, these combinations showed synergistic effects in only 1 / 11 and 3 / 11 isolates, respectively. Figure 1 ).

[0043] 5.3 Antimicrobial susceptibility at different β-lactamase / enzyme inhibitor concentration ratios To understand the combined effects of different ratios of aztreonam and different β-lactamase inhibitors, the sensitivity of these strains to different drug combinations was tested. Compared with aztreonam alone, the MIC reduction was most significant with the combination of aztreonam and avibactam, followed by the combination of aztreonam and clavulanic acid, and the combination of aztreonam and tazobactam. However, the MIC reduction was not significant when aztreonam and sulbactam were used in combination. Figure 2Among different concentration ratios, aztreonam / avibactam (avibactam: 4 µg / mL), aztreonam and clavulanic acid (2:1), aztreonam and sulbactam (2:1), and aztreonam-tazobactam (2:1) had the lowest MIC50 and MIC90 values. In the KPC gene-carrying group and the AmpC enzyme-encoding gene-carrying group (including strains carrying the MBL gene and those not carrying the carbapenemase gene), the MIC50 and MIC90 values ​​of aztreonam combined with avibactam were significantly lower than those of aztreonam alone; in other groups, only the MIC50 of aztreonam / tazobactam (2:1) was only slightly lower than that of either drug alone. In the MBL-carrying genome without the AmpC enzyme, the MIC50 and MIC90 values ​​of aztreonam / clavulanic acid (clavulanic acid: 4 µg / mL) were ≤0.12 µg / mL and 1 µg / mL, respectively. These values ​​are similar to those of aztreonam / avibactam (avibactam: 4 µg / mL), and significantly lower than the MIC values ​​of aztreonam monotherapy (MIC50: 128 µg / mL; MIC90: >128 µg / mL). In the groups without carbapenemase genes and those without AmpC enzyme genes, the MIC50 and MIC90 values ​​of aztreonam / clavulanic acid (2:1) were 16 µg / mL and 64 µg / mL, respectively, slightly lower than aztreonam monotherapy. In the non-AmpC enzyme gene-carrying groups (including the MBL gene-carrying group and the group without carbapenemase genomes), aztreonam / clavulanic acid (clavulanic acid: 4 µg / mL) was lower than that of aztreonam / sulbactam (2:1) (Table 4).

[0044] 5.4 Time-based sterilization test Based on the test results in Table 3, kpn-6, kpn-12, and kpn-47 were selected from the most frequently isolated bacterial species (Klebsiella pneumoniae). These strains can represent common ST types (ST307 and ST11) and carry common carbapenemase genes (NDM-5, KPC-2, and IMP-38). Figure 3 The results showed that kpn-6 carries the IMP-38 gene, as well as genes encoding TEM-1 (a narrow-spectrum β-lactamase), SHV-28 (an ESBL), and CTX-M-3 (an ESBL), with a MIC of 64 µg / mL when used alone as aztreonam. Compared with 32 µg / mL aztreonam alone, the addition of 4 µg / mL clavulanic acid to 0.25 µg / mL aztreonam significantly reduced bacterial concentration (by 10%). 3The bacterial concentration reduction achieved by 0.25 µg / mL aztreonam combined with avibactam or tazobactam was slightly lower than that achieved by clavulanic acid. The bactericidal effect of 32 µg / mL aztreonam combined with 4 µg / mL sulbactam at 10 hours was similar to that of aztreonam combined with clavulanic acid, but the bacterial concentration at 24 hours was higher than the initial bacterial concentration at 0 hours. For isolate kpn-12 containing the genes for KPC-2, TEM-1 (a narrow-spectrum β-lactamase), SHV-11 (an ESBL), and CTX-M-65 (an ESBL), the MIC value of aztreonam alone was >128 µg / mL, while 1 µg / mL aztreonam combined with 4 µg / mL avibactam reduced the bacterial concentration by 10%. 3 Compared to the group treated with 64 µg / mL aztreonam alone, the bacterial concentrations in other groups were slightly reduced after the addition of 4 µg / mL sulbactam, tazobactam, or clavulanic acid, respectively; among these drugs, clavulanic acid reduced bacterial concentrations less than tazobactam and sulbactam. For kpn-47 carrying the NDM-5, TEM-1 (a narrow-spectrum β-lactamase), SHV-11 (an ESBL), and CTX-M-3 (an ESBL) genes, the MIC value of aztreonam alone was 128 µg / mL; compared to 64 µg / mL aztreonam alone, the addition of 4 µg / mL sulbactam did not significantly reduce bacterial concentrations, while the addition of 4 µg / mL tazobactam reduced bacterial concentrations by 10%. 3 Aztreonam (0.25µg / mL) combined with 4µg / mL avibactam and 1µg / mL aztreonam combined with 4µg / mL clavulanic acid can achieve good synergistic bactericidal effects within 24 hours.

[0045] 6. Conclusion CRE isolates resistant to aztreonam carrying the MBL gene often also carry other β-lactamase genes. Besides MBL, various β-lactamases can also hydrolyze aztreonam and lead to resistance. Avibactam can inhibit NSBLs, ESBLs, and AmpC enzymes, but not MBLs. Therefore, the combined use of aztreonam and avibactam has a good synergistic antibacterial effect against aztreonam-resistant CRE isolates carrying multiple β-lactamase genes, while clavulanic acid, sulbactam, and tazobactam only inhibit some NSBLs and ESBLs.

[0046] In CRE isolates carrying the MBL gene but lacking the AmpC gene, aztreonam combined with clavulanic acid showed a similar synergistic antibacterial effect to aztreonam combined with avibactam, while the synergistic antibacterial effect of aztreonam combined with tazobactam was slightly lower than that of aztreonam combined with clavulanic acid; however, the effect of aztreonam combined with sulbactam was mostly not significant.

[0047] For CRE isolates carrying both MBL and AmpC enzyme genes, the antagonistic effect of aztreonam combined with clavulanic acid was stronger than that of the other three enzyme inhibitors. In CREs carrying the KPC gene, the combination of aztreonam and clavulanic acid had an additive effect, possibly due to the weak inhibitory effect of clavulanic acid on the KPC enzyme. Since the detection rate of the ESBL gene in *Escherichia coli* and *Klebsiella pneumoniae* is generally higher than that of the AmpC gene, while the detection rate of *Klebsiella pneumoniae* and *Enterobacter cloacae* complex is the opposite, the synergistic effect of aztreonam combined with clavulanic acid against aztreonam-resistant *Escherichia coli* or *Klebsiella pneumoniae* is stronger than that against *Klebsiella pneumoniae* or *Enterobacter cloacae* complex; in contrast, the antagonistic effect is weaker than that against *Klebsiella pneumoniae* or *Enterobacter cloacae* complex.

[0048] The concentration ratio of β-lactam antibiotics to β-lactamase inhibitors is also an important indicator for antimicrobial susceptibility testing and clinical anti-infective therapy selection in clinical microbiology laboratories. Among all tested isolates, the MIC50 and MIC90 values ​​were lowest when avibactam was fixed at 4 µg / mL, while the other three combination regimens showed the lowest MIC50 and MIC90 values ​​at a 2:1 ratio. This may be because avibactam is a non-suicidal β-lactamase inhibitor, unlike the other three β-lactamase inhibitors. Furthermore, when carrying the MBL gene but lacking the AmpC enzyme gene, the MIC50 or MIC90 values ​​of aztreonam combined with clavulanic acid at a fixed concentration of 4 µg / mL were similar to those of aztreonam combined with avibactam at a fixed concentration of 4 µg / mL, providing a reference for future PK / PD-based clinical anti-infective therapy.

[0049] A significant proportion of CRE isolates from children in the Shenzhen area that are resistant to aztreonam also carry MBL and other β-lactamase genes. Aztreonam / avibactam exhibits good antibacterial activity against all tested strains. For CRE isolates carrying the MBL gene but lacking the AmpC enzyme gene, aztreonam / clavulanic acid could be a more economical potential combination therapy than aztreonam / avibactam, but in vitro studies have shown it is currently unsuitable for CRE isolates carrying the AmpC enzyme gene.

[0050] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A pharmaceutical composition for inhibiting CRE, characterized in that: The active ingredients of the pharmaceutical composition consist of aztreonam and clavulanic acid.

2. The pharmaceutical composition for inhibiting CRE according to claim 1, characterized in that: The pharmaceutical composition is suitable for CRE isolates carrying the MBL gene but lacking the AmpC enzyme gene.

3. The pharmaceutical composition for inhibiting CRE according to claim 1, characterized in that: The concentration ratio of aztreonam to clavulanic acid in the pharmaceutical composition is 5:

1.

4. The pharmaceutical composition for inhibiting CRE according to claim 1, characterized in that: In the pharmaceutical composition, clavulanic acid is preferably used in combination with aztreonam at a fixed concentration of 4 µg / mL.

5. The pharmaceutical composition for inhibiting CRE according to claim 1, characterized in that: When the pharmaceutical composition is used in isolates carrying the MBL gene but lacking the AmpC enzyme gene, the MIC50 of clavulanic acid at 4 µg / mL is ≤0.12 µg / mL, and the MIC90 value is ≤1 µg / mL.

6. The pharmaceutical composition for inhibiting CRE according to claim 1, characterized in that: The pharmaceutical composition comprises the active ingredients aztreonam, clavulanic acid, and pharmaceutically acceptable excipients selected from at least one of pharmaceutically acceptable solvents, solubilizers, cosolvents, emulsifiers, osmotic pressure regulators, stabilizers, suspending agents, coating materials, anti-adhesives, integrators, penetration enhancers, pH adjusters, buffers, surfactants, absorbents, diluents, filter aids, and sustained-release materials.

7. The use of the pharmaceutical composition according to any one of claims 1-6 in inhibiting CRE.

8. The use of the pharmaceutical composition according to any one of claims 1-6, characterized in that: The pharmaceutical composition is used in the preparation of clinical anti-infective drugs for treatment.

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