Ca-EDTA restores the activity of ceftazidime-avibactam or aztreonam against carbapenemase-producing Klebsiellapneumoniae infections

Developing an effective therapy to overcome carbapenemase-positive Klebsiella pneumoniae (CPKp) is an important therapeutic challenge that must be addressed urgently. Here, we explored a Ca-EDTA combination with aztreonam or ceftazidime-avibactam in vitro and in vivo against diverse CPKp clinical isolates. The synergy testing of this study demonstrated that novel aztreonam-Ca-EDTA or ceftazidime-avibactam-Ca-EDTA combination was significantly effective in eliminating planktonic and mature biofilms in vitro, as well as eradicating CPKp infections in vivo. Both combinations revealed significant therapeutic efficacies in reducing bacterial load in internal organs and protecting treated mice from mortality. Conclusively, this is the first in vitro and in vivo study to demonstrate that novel aztreonam-Ca-EDTA or ceftazidime-avibactam-Ca-EDTA combinations provide favorable efficacy and safety for successful eradication of carbapenemase-producing Klebsiella pneumoniae planktonic and biofilm infections.

Multiple traces of monkeypox detected in non-sewered wastewater with sparse sampling from a densely populated metropolitan area in Asia

The monkeypox virus is excreted in the feces of infected individuals. Therefore, there is an interest in using viral load detection in wastewater for sentinel early surveillance at a community level and as a complementary approach to syndromic surveillance. We collected wastewater from 63 sewered and non-sewered locations in Bangkok city center between May and August 2022. Monkeypox viral DNA copy numbers were quantified using real-time polymerase chain reaction (PCR) and confirmed positive by Sanger sequencing. Monkeypox viral DNA was first detected in wastewater from the second week of June 2022, with a mean copy number of 16.4 copies/ml (n = 3). From the first week of July, the number of viral DNA copies increased to a mean copy number of 45.92 copies/ml. Positive samples were Sanger sequenced and confirmed the presence of the monkeypox virus. Our study is the first to detect monkeypox viral DNA in wastewater from various locations within Thailand. Results suggest that this could be a complementary source for detecting viral DNA and predicting upcoming outbreaks.

513. A randomized control trial on the effect of oral calcium carbonate to fecal levofloxacin concentration and microbiota diversity in healthy volunteers taking oral levofloxacin

Background

Levofloxacin(LVX) is used in treatment against bacterial infections but also affect the intestinal microbiota. Calcium(Ca) can form complex with LVX and prevent its absorption. Taking them at least 2 hours apart does not affect LVX peak plasma concentration(Cmax). Since, our in vitro study showed that Ca can increase LVX minimal inhibitory concentration (MIC) in some bacteria, we conducted a randomized control trial(RCT) to study whether oral CaCO3 can lower fecal LVX concentration and preserve gut microbiota diversity in healthy volunteers.

Methods

We conducted a RCT involving 20 healthy volunteers. All of them received a 5-day course of once-daily 500 mg LVX oral tablet at 8:00 AM. They were randomly assigned to treatment (taking 1,000 mg CaCO3 oral tablet twice daily at 12:00 PM and 6:00 PM) and control group (no CaCO3). The primary outcome was fecal LVX concentration by MIC and high performance liquid chromatography (HPLC) on day 2 and 5 after taking LVX. The secondary outcomes were fecal microbiota diversity by Shannon index (H) by 16s rDNA analysis, LVX Cmax by HPLC on day 1 and 5, and drug adverse events(AEs) in 4 weeks period. Figure 1.Demonstrates study methods.

Results

Each 10 volunteers were randomly assigned to treatment and control group. Mean fecal LVX concentration was higher in treatment than control group, 100.50 vs 53.21 µg/ml by MIC at day 5 (95% confidence interval [CI] 4.912, 89.73; p = 0.0242). There was no difference in mean fecal LVX concentrations by HPLC between treatment and control at day 2 and day 5. There was no difference in Cmax LVX at day 1 and day5 in treatment and control. No difference of fecal H, but treatment group had significantly declined in H(p = 0.0019). No serious AE, mild AEs were reported (3 in treatment and 5 in control groups), including nausea and diarrhea.

Primary outcome

Secondary outcome

Conclusion

In this study, CaCO3 is significantly related to higher fecal LVX level by MIC but does not significantly affect the LVX Cmax. However, rather than protecting gut microbiota from LVX, CaCO3 may lower gut microbiota diversity in the presence of LVX. Therefore, co-prescription of LVX and CaCO3 should be cautioned even without the concern about the absorption like when LVX is administered intravenously or when both drugs in oral forms are taken at different times.

Shannon index diversity

Figure 1 showed the Shannon diversity index. The mean diversity index of treatment group at day 0 was a bit higher than control group without statistical significance (p = 0.923). On day 2 and 5 of levofloxacin treatment, mean diversity index was higher in control group than in treatment group, also without statistical significance (p = 0.426 on day 2 and 0.237 on day 5). On day 14, mean diversity index was higher in treatment group. On day 28, mean diversity index was returned close to baseline at day 0.

Figure 3. Taxonomic profile

Details of microbiota composition in different taxa were demonstrated in Figure 2, different color represented different taxa compositions at genus level.

Disclosures

All Authors: No reported disclosures.

1073. Sulbactam-Durlobactam Has Potent Activity Against Multidrug-Resistant Acinetobacter baumannii Clinical Isolates From Thai Patients With Chronic Infections

Background

Due to the increase in multi-drug resistance (MDR) of Acinetobacter baumannii chronic infections with accompanying considerable morbidity and mortality, it is imperative to find effective novel treatments. Durlobactam (DUR) is a potent broad-spectrum inhibitor of Ambler classes A, C and D serine β-lactamases that effectively restores sulbactam (SUL) activity against MDR A.baumannii isolates. SUL-DUR is currently in late-stage development for the treatment of infections caused by Acinetobacter spp., including drug resistant isolates. In this study, we sought to evaluate potency of SUL-DUR against MDR A. baumannii isolates collected from Thai patients with chronic infections.

Methods

Non-duplicative clinical strains were isolated during 2016–2019 from 200 chronically infected patients in different medical wards with a variety of different infections at King Chulalongkorn Memorial Hospital, Bangkok, Thailand. Susceptibility testing of SUL-DUR and comparator agents was performed according to CLSI guidelines. SUL-DUR was also tested on a background of imipenem (IPM) therapy (SUL-IPM titrated at a 1:1 ratio plus DUR fixed at 4 mg/L). Data analysis was performed using CLSI and EUCAST breakpoint criteria where available.

Results

This collection of isolates was 92% sulbactam-resistant (using a breakpoint of 4 mg/L), 91% carbapenem-resistant, 74% amikacin resistant and 8% colistin resistant. In contrast, the SUL-DUR MIC90 was 4 mg/L compared with 64 mg/L for sulbactam alone. SUL-DUR was equally potent across antibiotic-resistant subsets. Only 6 isolates (3%) had SUL-DUR MIC values >4 mg/L. Interestingly, addition of imipenem to SUL-DUR showed similar potency as SUL-DUR alone, with an MIC90 of 2 mg/L.

Conclusion

SUL-DUR showed potent in vitro activity against contemporary clinical isolates from a hospital in Bangkok, Thailand. If successfully developed, SUL-DUR may be an important new therapeutic option for the treatment of MDR Acinetobacter infections.

Disclosures

Alita Miller, PhD, Entasis Therapeutics (Employee)

1355. Cluster of Multi-drug Resistance Neisseria gonorrhoeae Isolates with Reduce Ceftriaxone Susceptibility, First Report in Thailand

Background

Rapid emergence of global azithromycin resistance, with ceftriaxone reduce susceptibility/resistant strains, threatens the current recommends dual therapy with ceftriaxone and azithromycin for gonorrhea to ensure effective treatment. Thailand is a major risk area for gonorrhea because it as a key destination for sex tourism industry, where antibiotic resistance gonorrhea can spread easily and quickly across the region. Here, we identified a first cluster of Neisseria gonorrhoeae isolates with decreased ceftriaxone susceptibility in Thailand.

Methods

A 134 N. gonorrhoeae isolates collected from Thai Red Cross Anonymous Clinic, Bangkok, during 2016–2018 were studied. Broth micro-dilution and plate dilution methods to define resistance or decreased susceptibilityaccording to CLSI guidelines. Select isolates were subjected to whole genome sequencing with an Illumina MiSeq V2 instrument and analysis using CLCBio Genomics Workbench v6.5. Molecular docking studies were carried out to understand binding mode analysis and orientation of ceftriaxone in the active site of PBP2. Biofilm formation measured by confocal laser scanning microscopy.

Results

Among the N. gonorrhoeae clinical isolates, two isolates had significant reduced susceptibility to ceftriaxone (MICs of 0.125 mg/L), which were isolated from urethral swab in male heterosexual patients. Both were multidrug resistance and strong biofilm producers with ceftriaxone tolerance (MBEC > 128 mg/L). One isolate was resistant to azithromycin (MIC of 1 mg/L), and other one remained susceptible (MIC of 0.5 mg/L). Reduced susceptibility to ceftriaxone associated with alterations in PBP2, PBP1, PorB, MtrR, and mtrR promoter region with one belonged to ST7235 and second one had new allele number of tbpB with new sequence type (ST). Ceftriaxone weakly occupy the active site of mosaic XXXIV penicillin-binding protein 2 (PBP2) variant in both. Molecular epidemiology results reviled that both isolates display similarities with isolates from UK, USA, and Netherlands.

Conclusion

This first cluster of genetically related gonococcal isolates with decreased ceftriaxone susceptibility may bring threat of treatment failure in Thailand. Also highlighted the importance of maintaining surveillance for antimicrobial resistance.

Disclosures

All Authors: No reported disclosures

Novel colistin-EDTA combination for successful eradication of colistin-resistant Klebsiella pneumoniae catheter-related biofilm infections

Development of an effective therapy to overcome colistin resistance in Klebsiella pneumoniae, a common pathogen causing catheter-related biofilm infections in vascular catheters, has become a serious therapeutic challenge that must be addressed urgently. Although colistin and EDTA have successful roles for eradicating biofilms, no in vitro and in vivo studies have investigated their efficacy in catheter-related biofilm infections of colistin-resistant K. pneumoniae. In this study, colistin resistance was significantly reversed in both planktonic and mature biofilms of colistin-resistant K. pneumoniae by a combination of colistin (0.25-1 µg/ml) with EDTA (12 mg/ml). This novel colistin-EDTA combination was also demonstrated to have potent efficacy in eradicating colistin-resistant K. pneumoniae catheter-related biofilm infections, and eliminating the risk of recurrence in vivo. Furthermore, this study revealed significant therapeutic efficacy of colistin-EDTA combination in reducing bacterial load in internal organs, lowering serum creatinine, and protecting treated mice from mortality. Altered in vivo expression of different virulence genes indicate bacterial adaptive responses to survive in hostile environments under different treatments. According to these data discovered in this study, a novel colistin-EDTA combination provides favorable efficacy and safety for successful eradication of colistin-resistant K. pneumonia catheter-related biofilm infections.

Multidrug-resistant Neisseria gonorrhoeae infection in heterosexual men with reduced susceptibility to ceftriaxone, first report in Thailand

The global rapid emergence of azithromycin/ceftriaxone resistant Neisseria gonorrhoeae threatens current recommend azithromycin/ceftriaxone dual therapy for gonorrhea to ensure effective treatment. Here, we identified the first two N. gonorrhoeae isolates with decreased ceftriaxone susceptibility in Thailand. Among 134 N. gonorrhoeae isolates collected from Thai Red Cross Anonymous Clinic, Bangkok, two isolates (NG-083 and NG-091) from urethral swab in male heterosexual patients had reduced susceptibility to ceftriaxone (MICs of 0.125 mg/L). Both were multidrug resistant and strong biofilm producers with ceftriaxone tolerance (MBEC > 128 mg/L). NG-083 and NG-091 remained susceptible to azithromycin (MIC of 1 mg/L and 0.5 mg/L, respectively). Reduced susceptibility to ceftriaxone was associated with alterations in PBP2, PBP1, PorB, MtrR, and mtrR promoter region. NG-083 belonged to sequence type (ST) 7235 and NG-091 has new allele number of tbpB with new ST. Molecular docking revealed ceftriaxone weakly occupied the active site of mosaic XXXIV penicillin-binding protein 2 variant in both isolates. Molecular epidemiology results revealed that both isolates display similarities with isolates from UK, USA, and The Netherlands. These first two genetically related gonococcal isolates with decreased ceftriaxone susceptibility heralds the threat of treatment failure in Thailand, and importance of careful surveillance.

Tracking COVID-19 with wastewater to understand asymptomatic transmission

INTRODUCTION

SARS-CoV-2 RNA is excreted in feces of most patients, therefore viral load in wastewater can be used as a surveillance tool to develop an early warning system to help and manage future pandemics.

METHODS

We collected wastewater from 24 random locations at Bangkok city center and 26 nearby suburbs from July to December 2020. SARS-CoV-2 RNA copy numbers were measured using real-time polymerase chain reaction (PCR).

RESULTS

SARS-CoV-2 RNA was detected in wastewater from both the city center and suburbs. Except for July, there were no significant differences in copy numbers between the city center and suburbs. Between October and November, a sharp rise in copy number was observed in both places followed by two to three times increase in December, related to SARS-CoV-2 cases reported for same month.

CONCLUSIONS

Our study provided the first dataset related to SARS-CoV-2 viral RNA in the wastewater of Bangkok. Our results suggest that wastewater could be used as a complementary source for detecting viral RNA and predicting upcoming outbreaks and waves.