1292. Evaluation of Synergy with Piperacillin/Tazobactam plus Meropenem Against Carbapenemase-Producing Klebsiella pneumoniae and Enterobacter cloacae Using ETEST

Abstract Background Carbapenem-resistant Enterobacterales are considered an urgent threat for patients in healthcare facilities, causing infections with significant morbidity and mortality. Most isolates are multidrug resistant with limited treatment options, so combination therapy is an alternative. Recently, synergy with piperacillin/tazobactam (P/T) + meropenem (MP) was demonstrated against 7/10 (70%) KPC-producing Escherichia coli and 9/10 (90%) OXA-48-producing K. pneumoniae using time-kill assay (Lawandi et al, 2021). The aim of the present study was to further evaluate the combination of P/T + MP against KPC-producing Enterobacter cloacae, in addition to OXA-producing K. pneumoniae using our rapid ETEST MIC:MIC synergy method. Methods 14 carbapenemase-producing isolates: 7 OXA-48-like K. pneumoniae (1 OXA-48, 4 OXA-181, 2 OXA-232) and 7 KPC-producing E. cloacae (1 KPC-2, 4 KPC-3, 1 KPC-4, 1 KPC-6) were obtained from the CDC and FDA Antibiotic Resistance Isolate Bank. ETEST MICs for P/T and MP and our ETEST synergy method were performed in triplicate for each isolate. The summation fractional inhibitory concentration was calculated, and the mean value was interpreted as: < 0.5 synergy; > 0.5-1 additivity; > 1-4 indifference; and > 4 antagonism. Results MICs (µg/mL) ranged: MP, 0.5 to > 32 (14% susceptible) and P/T, 96/4 to > 256/4 (all resistant). The combination of P/T + MP showed synergy (3) or additivity (2) against 5/7 (71%) OXA-producing K. pneumoniae and synergy (6) or additivity (1) against all 7 KPC-producing E. cloacae. No antagonism was detected. Conclusion Using our ETEST MIC:MIC method, the combination of P/T + MP demonstrated synergy or additivity in 5/7 OXA-producing K. pneumoniae and 7/7 KPC-producing E. cloacae, similar to previously published findings showing synergy in 7/10 KPC-producing E. coli and 9/10 OXA-48-producing K. pneumoniae using time-kill assay. Our ETEST synergy method is simple to use and should be evaluated more extensively. Regardless of the method used, results may or may not correlate in an in vivo setting. In vivo studies are needed. Disclosures All Authors: No reported disclosures

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Synergistic Activity of Colistin-Containing Combinations against Colistin-ResistantEnterobacteriaceae

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00873-18 ◽

2018 ◽

Vol 62 (10) ◽

Cited By ~ 28

Author(s):

Thea Brennan-Krohn ◽

Alejandro Pironti ◽

James E. Kirby

Keyword(s):

Treatment Options ◽

Multidrug Resistant ◽

Synergistic Activity ◽

Gram Negative ◽

Content Type ◽

Carbapenem Resistant ◽

Resistant Strains ◽

Bacterial Outer Membrane ◽

Time Kill ◽

Synergistic Combinations

ABSTRACTResistance to colistin, a polypeptide drug used as an agent of last resort for the treatment of infections caused by multidrug-resistant (MDR) and extensively drug-resistant (XDR) Gram-negative bacteria, including carbapenem-resistantEnterobacteriaceae(CRE), severely limits treatment options and may even transform an XDR organism into one that is pan-resistant. We investigated the synergistic activity of colistin in combination with 19 antibiotics against a collection of 20 colistin-resistantEnterobacteriaceaeisolates, 15 of which were also CRE. All combinations were tested against all strains using an inkjet printer-assisted digital dispensing checkerboard array, and the activities of those that demonstrated synergy by this method were evaluated against a single isolate in a time-kill synergy study. Eighteen of 19 combinations demonstrated synergy against two or more isolates, and the 4 most highly synergistic combinations (colistin combined with linezolid, rifampin, azithromycin, and fusidic acid) were synergistic against ≥90% of strains. Sixteen of 18 combinations (88.9%) that were synergistic in the checkerboard array were also synergistic in a time-kill study. Our findings demonstrate that colistin in combination with a range of antibiotics, particularly protein and RNA synthesis inhibitors, exhibits synergy against colistin-resistant strains, suggesting that colistin may exert a subinhibitory permeabilizing effect on the Gram-negative bacterial outer membrane even in isolates that are resistant to it. These findings suggest that colistin combination therapy may have promise as a treatment approach for patients infected with colistin-resistant XDR Gram-negative pathogens.

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Bactericidal Efficacy of Meropenem in Combination with Cefmetazole against IMP-producing Carbapenem-Resistant Enterobacteriaceae

10.21203/rs.2.15806/v2 ◽

2019 ◽

Author(s):

Ryuichiro Abe ◽

Hideharu Hagiya ◽

Yukihiro Akeda ◽

Norihisa Yamamoto ◽

Yoshikazu Ishii ◽

...

Keyword(s):

Combination Therapy ◽

Animal Studies ◽

Bactericidal Effect ◽

E Coli ◽

Carbapenem Resistant ◽

Enterobacter Hormaechei ◽

Time Kill ◽

Carbapenem Resistant Enterobacteriaceae

Abstract Objective: Carbapenem-resistant Enterobacteriaceae (CRE) are among the most severe threats to public and clinical health because of their high levels of resistance to various antibiotics. We assessed the efficacy of combination therapy with meropenem (MEM) and cefmetazole (CMZ) against Imipenemase (IMP)-producing CRE, using the checkerboard method and time-killing assay on 13 Enterobacteriaceae isolates harboring blaIMP-1 (4 Enterobacter hormaechei, 5 Escherichia coli, and 4 Klebsiella pneumoniae isolates) and 13 isolates harboring blaIMP-6 (8 E. coli and 5 K. pneumoniae isolates). Results: Minimum inhibitory concentrations (MICs) of MEM and CMZ ranged from 2 to 64 and 64 to 2048 μg/mL, respectively. Checkerboard method demonstrated the synergy of the MEM/CMZ combination in all the tested IMP-producing CRE isolates, and the time-kill assay indicated a bactericidal effect for both blaIMP-1 and blaIMP-6 positive CRE when MEM/CMZ combination was used. In vitro, the MEM/CMZ combination was potentially effective against IMP-1- or IMP-6-producing CRE. Further investigations including in vivo animal studies and clinical studies are warranted to corroborate the clinical utility of the novel combination therapy.

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Bactericidal Efficacy of Meropenem in Combination with Cefmetazole against IMP-producing Carbapenem-Resistant Enterobacteriaceae

10.21203/rs.2.15806/v1 ◽

2019 ◽

Author(s):

Ryuichiro Abe ◽

Hideharu Hagiya ◽

Yukihiro Akeda ◽

Norihisa Yamamoto ◽

Yoshikazu Ishii ◽

...

Keyword(s):

Combination Therapy ◽

Animal Studies ◽

Bactericidal Effect ◽

E Coli ◽

Carbapenem Resistant ◽

Enterobacter Hormaechei ◽

Time Kill ◽

Carbapenem Resistant Enterobacteriaceae

Abstract Objective: Carbapenem-resistant Enterobacteriaceae (CRE) are among the most severe threats to public and clinical health because of their high levels of resistance to various antibiotics. We assessed the efficacy of combination therapy with meropenem (MEM) and cefmetazole (CMZ) against IMP-producing CRE, using the checkerboard method and time-killing assay on 13 Enterobacteriaceae isolates harboring blaIMP-1 (4 Enterobacter hormaechei, 5 Escherichia coli, and 4 Klebsiella pneumoniae isolates) and 13 isolates harboring blaIMP-6 (8 E. coli and 5 K. pneumoniae isolates). Results: Minimum inhibitory concentrations (MICs) of MEM and CMZ ranged from 2 to 64 and 64 to 2048 μg/mL, respectively. Checkerboard method demonstrated the synergy of the MEM/CMZ combination in all the tested IMP-producing CRE isolates, and the time-kill assay indicated a bactericidal effect for both blaIMP-1 and blaIMP-6 positive CRE when MEM/CMZ combination was used. In vitro, the MEM/CMZ combination was potentially effective against IMP-1- or IMP-6-producing CRE. Further investigations including in vivo animal studies and clinical studies are warranted to corroborate the clinical utility of the novel combination therapy.

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Bactericidal efficacy of meropenem in combination with cefmetazole against IMP-producing carbapenem-resistant Enterobacteriaceae

BMC Research Notes ◽

10.1186/s13104-019-4779-x ◽

2019 ◽

Vol 12 (1) ◽

Cited By ~ 1

Author(s):

Ryuichiro Abe ◽

Hideharu Hagiya ◽

Yukihiro Akeda ◽

Norihisa Yamamoto ◽

Yoshikazu Ishii ◽

...

Keyword(s):

Combination Therapy ◽

Animal Studies ◽

Bactericidal Effect ◽

The Novel ◽

E Coli ◽

Carbapenem Resistant ◽

Enterobacter Hormaechei ◽

Time Kill

Abstract Objective Carbapenem-resistant Enterobacteriaceae (CRE) are among the most severe threats to public and clinical health because of their high levels of resistance to various antibiotics. We assessed the efficacy of combination therapy with meropenem (MEM) and cefmetazole (CMZ) against Imipenemase (IMP)-producing CRE, using the checkerboard method and time-killing assay on 13 Enterobacteriaceae isolates harboring blaIMP-1 (4 Enterobacter hormaechei, 5 Escherichia coli, and 4 Klebsiella pneumoniae isolates) and 13 isolates harboring blaIMP-6 (8 E. coli and 5 K. pneumoniae isolates). Results Minimum inhibitory concentrations (MICs) of MEM and CMZ ranged from 2 to 64 and 64 to 2048 μg/mL, respectively. Checkerboard method demonstrated the synergy of the MEM/CMZ combination in all the tested IMP-producing CRE isolates, and the time-kill assay indicated a bactericidal effect for both blaIMP-1 and blaIMP-6 positive CRE when MEM/CMZ combination was used. In vitro, the MEM/CMZ combination was potentially effective against IMP-1- or IMP-6-producing CRE. Further investigations including in vivo animal studies and clinical studies are warranted to corroborate the clinical utility of the novel combination therapy.

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Antimicrobial Effects of Minocycline, Tigecycline, Ciprofloxacin, and Levofloxacin against Elizabethkingia anophelis using In Vitro Time-Kill Assays and In Vivo Zebrafish Animal Models

Antibiotics ◽

10.3390/antibiotics10030285 ◽

2021 ◽

Vol 10 (3) ◽

pp. 285

Author(s):

Jiun-Nong Lin ◽

Chung-Hsu Lai ◽

Yi-Han Huang ◽

Chih-Hui Yang

Keyword(s):

Animal Models ◽

Antibacterial Activities ◽

Bactericidal Effect ◽

Multidrug Resistant ◽

Inhibitory Effect ◽

In Vivo Studies ◽

Therapeutic Effects ◽

Time Kill

Elizabethkingia anophelis is a multidrug-resistant pathogen. This study evaluated the antimicrobial activity of minocycline, tigecycline, ciprofloxacin, and levofloxacin using in vitro time-kill assays and in vivo zebrafish animal models. The E. anophelis strain ED853-49 was arbitrarily selected from a bacterial collection which was concomitantly susceptible to minocycline, tigecycline, ciprofloxacin, and levofloxacin. The antibacterial activities of single agents at 0.5–4 × minimum inhibitory concentration (MIC) and dual-agent combinations at 2 × MIC using time-kill assays were investigated. The therapeutic effects of antibiotics in E. anophelis-infected zebrafish were examined. Both minocycline and tigecycline demonstrated bacteriostatic effects but no bactericidal effect. Minocycline at concentrations ≥2 × MIC and tigecycline at concentrations ≥3 × MIC exhibited a long-standing inhibitory effect for 48 h. Bactericidal effects were observed at ciprofloxacin and levofloxacin concentrations of ≥3 × MIC within 24 h of initial inoculation. Rapid regrowth of E. anophelis occurred after the initial killing phase when ciprofloxacin was used, regardless of the concentration. Levofloxacin treatment at the concentration of ≥2 × MIC consistently resulted in the long-lasting and sustainable inhibition of bacterial growth for 48 h. The addition of minocycline or tigecycline weakened the killing effect of fluoroquinolones during the first 10 h. The minocycline-ciprofloxacin or minocycline–levofloxacin combinations achieved the lowest colony-forming unit counts at 48 h. Zebrafish treated with minocycline or a combination of minocycline and levofloxacin had the highest survival rate (70%). The results of these in vitro and in vivo studies suggest that the combination of minocycline and levofloxacin is the most effective therapy approach for E. anophelis infection.

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Carbapenem-ResistantKlebsiella pneumoniaeExhibiting Clinically Undetected Colistin Heteroresistance Leads to Treatment Failure in a Murine Model of Infection

mBio ◽

10.1128/mbio.02448-17 ◽

2018 ◽

Vol 9 (2) ◽

pp. e02448-17 ◽

Cited By ~ 24

Author(s):

Victor I. Band ◽

Sarah W. Satola ◽

Eileen M. Burd ◽

Monica M. Farley ◽

Jesse T. Jacob ◽

...

Keyword(s):

Treatment Failure ◽

Treatment Options ◽

The United States ◽

Multidrug Resistant ◽

Genetic Mutation ◽

Clinical Diagnostics ◽

Carbapenem Resistant ◽

Line Therapy ◽

A Minor

ABSTRACTAntibiotic resistance is a growing crisis and a grave threat to human health. It is projected that antibiotic-resistant infections will lead to 10 million annual deaths worldwide by the year 2050. Among the most significant threats are carbapenem-resistantEnterobacteriaceae(CRE), including carbapenem-resistantKlebsiella pneumoniae(CRKP), which lead to mortality rates as high as 40 to 50%. Few treatment options are available to treat CRKP, and the polymyxin antibiotic colistin is often the “last-line” therapy. However, resistance to colistin is increasing. Here, we identify multidrug-resistant, carbapenemase-positive CRKP isolates that were classified as susceptible to colistin by clinical diagnostics yet harbored a minor subpopulation of phenotypically resistant cells. Within these isolates, the resistant subpopulation became predominant after growth in the presence of colistin but returned to baseline levels after subsequent culture in antibiotic-free media. This indicates that the resistance was phenotypic, rather than due to a genetic mutation, consistent with heteroresistance. Importantly, colistin therapy was unable to rescue mice infected with the heteroresistant strains. These findings demonstrate that colistin heteroresistance may causein vivotreatment failure duringK. pneumoniaeinfection, threatening the use of colistin as a last-line treatment for CRKP. Furthermore, these data sound the alarm for use of caution in interpreting colistin susceptibility test results, as isolates identified as susceptible may in fact resist antibiotic therapy and lead to unexplained treatment failures.IMPORTANCEThis is the first report of colistin-heteroresistantK. pneumoniaein the United States. Two distinct isolates each led to colistin treatment failure in anin vivomodel of infection. The data are worrisome, especially since the colistin heteroresistance was not detected by current diagnostic tests. As these isolates were carbapenem resistant, clinicians might turn to colistin as a last-line therapy for infections caused by such strains, not knowing that they in fact harbor a resistant subpopulation of cells, potentially leading to treatment failure. Our findings warn that colistin susceptibility testing results may be unreliable due to undetected heteroresistance and highlight the need for more accurate and sensitive diagnostics.

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In Vivo Pharmacodynamics of β-Lactams/Nacubactam against Carbapenem-Resistant and/or Carbapenemase-Producing Enterobacter cloacae and Klebsiella pneumoniae in Murine Pneumonia Model

Antibiotics ◽

10.3390/antibiotics10101179 ◽

2021 ◽

Vol 10 (10) ◽

pp. 1179

Author(s):

Mao Hagihara ◽

Hideo Kato ◽

Toshie Sugano ◽

Hayato Okade ◽

Nobuo Sato ◽

...

Keyword(s):

Antimicrobial Activity ◽

Klebsiella Pneumoniae ◽

Treatment Options ◽

Enterobacter Cloacae ◽

Antimicrobial Activities ◽

Combination Therapies ◽

Carbapenem Resistant ◽

Combination Regimens

Carbapenem-resistant Enterobacterales (CRE) and carbapenemase-producing Enterobacterales (CPE) have become global threats. CRE− and CPE− derived infections have been associated with high mortality due to limited treatment options. Nacubactam is a β-lactamase inhibitor and belongs to the new class of diazabicyclooctane. The agent has an in vitro antimicrobial activity against several classes of β-lactamase-producing Enterobacterales. This study evaluated antimicrobial activity of combination therapies including β-lactams (aztreonam, cefepime, and meropenem) and nacubactam against four Enterobacter cloacae and six Klebsiella pneumoniae isolates with murine pneumonia model. Based on changes in bacterial quantity, antimicrobial activities of some regimens were assessed. Combination therapies including β-lactams (aztreonam, cefepime, and meropenem) with nacubactam showed enhanced antimicrobial activity against CRE E. cloacae (−3.70 to −2.08 Δlog10 CFU/lungs) and K. pneumoniae (−4.24 to 1.47 Δlog10 CFU/lungs) with IMP-1, IMP-6, or KPC genes, compared with aztreonam, cefepime, meropenem, and nacubactam monotherapies. Most combination therapies showed bacteriostatic (−3.0 to 0 Δlog10 CFU/lungs) to bactericidal (<−3.0 Δlog10 CFU/lungs) activities against CRE isolates. This study revealed that combination regimens with β-lactams (aztreonam, cefepime, and meropenem) and nacubactam are preferable candidates to treat pneumonia due to CRE and CPE.

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In Vitro Pharmacodynamic Analyses Help Guide the Treatment of Multidrug-Resistant Enterococcus faecium and Carbapenem-Resistant Enterobacter cloacae Bacteremia in a Liver Transplant Patient

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz545 ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Eric Wenzler ◽

Maressa Santarossa ◽

Kevin A Meyer ◽

Amanda T Harrington ◽

Gail E Reid ◽

...

Keyword(s):

Liver Transplant ◽

Enterococcus Faecium ◽

Transplant Patient ◽

Enterobacter Cloacae ◽

Multidrug Resistant ◽

Patient Specific ◽

Liver Transplant Patient ◽

Carbapenem Resistant

Abstract Background Infections due to multidrug-resistant pathogens are particularly deadly and difficult to treat in immunocompromised patients, where few data exist to guide optimal antimicrobial therapy. In the absence of adequate clinical data, in vitro pharmacokinetic (PK)/pharmacodynamic (PD) analyses can help to design treatment regimens that are bactericidal and may be clinically effective. Methods We report a case in which in vitro pharmacodynamic analyses were utilized to guide the treatment of complex, recurrent bacteremias due to vancomycin-, daptomycin-, and linezolid-resistant Enterococcus faecium and carbapenem-resistant Enterobacter cloacae complex in a liver transplant patient. Results Whole-genome sequencing revealed unique underlying resistance mechanisms and explained the rapid evolution of phenotypic resistance and complicated intrahost genomic dynamics observed in vivo. Performing this comprehensive genotypic and phenotypic testing and time-kill analyses, along with knowledge of institution and patient-specific factors, allowed us to use precision medicine to design a treatment regimen that maximized PK/PD. Conclusions This work provides a motivating example of clinicians and scientists uniting to optimize care in the era of escalating antimicrobial resistance.

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Bactericidal Efficacy of Meropenem in Combination with Cefmetazole against IMP-producing Carbapenem-Resistant Enterobacteriaceae

10.21203/rs.2.15806/v3 ◽

2019 ◽

Author(s):

Ryuichiro Abe ◽

Hideharu Hagiya ◽

Yukihiro Akeda ◽

Norihisa Yamamoto ◽

Yoshikazu Ishii ◽

...

Keyword(s):

Combination Therapy ◽

Animal Studies ◽

Bactericidal Effect ◽

E Coli ◽

Carbapenem Resistant ◽

Enterobacter Hormaechei ◽

Time Kill ◽

Carbapenem Resistant Enterobacteriaceae

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Effects of Probiotics in the Management of Infected Chronic Wounds: From Cell Culture to Human Studies

Current Clinical Pharmacology ◽

10.2174/1574884714666191111130630 ◽

2020 ◽

Vol 15 (3) ◽

pp. 193-206

Author(s):

Brognara Lorenzo ◽

Salmaso Luca ◽

Mazzotti Antonio ◽

Di M. Alberto ◽

Faldini Cesare ◽

...

Keyword(s):

Chronic Wounds ◽

Animal Experiments ◽

Multidrug Resistant ◽

Preliminary Evidence ◽

Human Studies ◽

In Vivo Studies ◽

Resistant Bacteria ◽

Keywords Probiotics

Background: Chronic wounds are commonly associated with polymicrobial biofilm infections. In the last years, the extensive use of antibiotics has generated several antibiotic-resistant variants. To overcome this issue, alternative natural treatments have been proposed, including the use of microorganisms like probiotics. The aim of this manuscript was to review current literature concerning the application of probiotics for the treatment of infected chronic wounds. Methods: Relevant articles were searched in the Medline database using PubMed and Scholar, using the keywords “probiotics” and “wound” and “injuries”, “probiotics” and “wound” and “ulcer”, “biofilm” and “probiotics” and “wound”, “biofilm” and “ulcer” and “probiotics”, “biofilm” and “ulcer” and “probiotics”, “probiotics” and “wound”. Results: The research initially included 253 articles. After removal of duplicate studies, and selection according to specific inclusion and exclusion criteria, 19 research articles were included and reviewed, accounting for 12 in vitro, 8 in vivo studies and 2 human studies (three articles dealing with animal experiments included also in vitro testing). Most of the published studies about the effects of probiotics for the treatment of infected chronic wounds reported a partial inhibition of microbial growth, biofilm formation and quorum sensing. Discussion: The application of probiotics represents an intriguing option in the treatment of infected chronic wounds with multidrug-resistant bacteria; however, current results are difficult to compare due to the heterogeneity in methodology, laboratory techniques, and applied clinical protocols. Lactobacillus plantarum currently represents the most studied strain, showing a positive application in burns compared to guideline treatments, and an additional mean in chronic wound infections. Conclusions: Although preliminary evidence supports the use of specific strains of probiotics in certain clinical settings such as infected chronic wounds, large, long-term clinical trials are still lacking, and further research is needed.

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