Pub Date : 2024-09-04Epub Date: 2024-08-13DOI: 10.1128/aac.01576-23
Rodney Ogwang, Victor Osoti, Kevin Wamae, Leonard Ndwiga, Kelvin Muteru, Albert Ningwa, James Tuju, Sam Kinyanjui, Faith Osier, Kevin Marsh, Philip Bejon, Richard Idro, Lynette Isabella Ochola-Oyier
The emergence of drug-resistant Plasmodium falciparum parasites in sub-Saharan Africa will substantially challenge malaria control. Here, we evaluated the frequency of common drug resistance markers among adolescents from Northern Uganda with asymptomatic infections. We used an established amplicon deep sequencing strategy to screen dried blood spot samples collected from 2016 to 2017 during a reported malaria epidemic within the districts of Kitgum and Pader in Northern Uganda. We screened single-nucleotide polymorphisms within: kelch13 (Pfk13), dihydropteroate synthase (Pfdhps), multidrug resistance-1 (Pfmdr1), dihydrofolate reductase (Pfdhfr), and apical membrane antigen (Pfama1) genes. Within the study population, the median age was 15 years (14.3-15.0, 95% CI), and 54.9% (78/142) were Plasmodium positive by 18S rRNA qPCR, which were subsequently targeted for sequencing analysis. We observed a high frequency of resistance markers particularly for sulfadoxine-pyrimethamine (SP), with no wild-type-only parasites observed for Pfdhfr (N51I, C59R, and S108N) and Pfdhps (A437G and K540E) mutations. Within Pfmdr1, mixed infections were common for NF/NY (98.5%). While for artemisinin resistance, in kelch13, there was a high frequency of C469Y (34%). Using the pattern for Pfama1, we found a high level of polygenomic infections with all individuals presenting with complexity of infection greater than 2 with a median of 6.9. The high frequency of the quintuple SP drug-resistant parasites and the C469Y artemisinin resistance-associated mutation in asymptomatic individuals suggests an earlier high prevalence than previously reported from symptomatic malaria surveillance studies (in 2016/2017). Our data demonstrate the urgency for routine genomic surveillance programs throughout Africa and the value of deep sequencing.
{"title":"A retrospective analysis of <i>P. falciparum</i> drug resistance markers detects an early (2016/17) high prevalence of the k13 C469Y mutation in asymptomatic infections in Northern Uganda.","authors":"Rodney Ogwang, Victor Osoti, Kevin Wamae, Leonard Ndwiga, Kelvin Muteru, Albert Ningwa, James Tuju, Sam Kinyanjui, Faith Osier, Kevin Marsh, Philip Bejon, Richard Idro, Lynette Isabella Ochola-Oyier","doi":"10.1128/aac.01576-23","DOIUrl":"10.1128/aac.01576-23","url":null,"abstract":"<p><p>The emergence of drug-resistant <i>Plasmodium falciparum</i> parasites in sub-Saharan Africa will substantially challenge malaria control. Here, we evaluated the frequency of common drug resistance markers among adolescents from Northern Uganda with asymptomatic infections. We used an established amplicon deep sequencing strategy to screen dried blood spot samples collected from 2016 to 2017 during a reported malaria epidemic within the districts of Kitgum and Pader in Northern Uganda. We screened single-nucleotide polymorphisms within: kelch13 (<i>Pfk13</i>), dihydropteroate synthase (<i>Pfdhps</i>), multidrug resistance-1 (<i>Pfmdr1</i>), dihydrofolate reductase (<i>Pfdhfr</i>), and apical membrane antigen (<i>Pfama1</i>) genes. Within the study population, the median age was 15 years (14.3-15.0, 95% CI), and 54.9% (78/142) were <i>Plasmodium</i> positive by 18S rRNA qPCR, which were subsequently targeted for sequencing analysis. We observed a high frequency of resistance markers particularly for sulfadoxine-pyrimethamine (SP), with no wild-type-only parasites observed for <i>Pfdhfr</i> (N51I, C59R, and S108N) and <i>Pfdhps</i> (A437G and K540E) mutations. Within <i>Pfmdr1,</i> mixed infections were common for NF/NY (98.5%). While for artemisinin resistance, in kelch13, there was a high frequency of C469Y (34%). Using the pattern for <i>Pfama1,</i> we found a high level of polygenomic infections with all individuals presenting with complexity of infection greater than 2 with a median of 6.9. The high frequency of the quintuple SP drug-resistant parasites and the C469Y artemisinin resistance-associated mutation in asymptomatic individuals suggests an earlier high prevalence than previously reported from symptomatic malaria surveillance studies (in 2016/2017). Our data demonstrate the urgency for routine genomic surveillance programs throughout Africa and the value of deep sequencing.</p>","PeriodicalId":8152,"journal":{"name":"Antimicrobial Agents and Chemotherapy","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11382623/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141970473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-04Epub Date: 2024-08-13DOI: 10.1128/aac.00650-24
Michèle M Molendijk, Bouke K H L Boekema, Kirby R Lattwein, Marcel Vlig, Lonneke G M Bode, Marion P G Koopmans, Annelies Verbon, Miranda de Graaf, Willem J B van Wamel
Burn wounds are a major burden, with high mortality rates due to infections. Staphylococcus aureus is a major causative agent of burn wound infections, which can be difficult to treat because of antibiotic resistance and biofilm formation. An alternative to antibiotics is the use of bacteriophages, viruses that infect and kill bacteria. We investigated the efficacy of bacteriophage therapy for burn wound infections, in both a porcine and a newly developed human ex vivo skin model. In both models, the efficacy of a reference antibiotic treatment (fusidic acid) and bacteriophage treatment was determined for a single treatment, successive treatment, and prophylaxis. Both models showed a reduction in bacterial load after a single bacteriophage treatment. Increasing the frequency of bacteriophage treatments increased bacteriophage efficacy in the human ex vivo skin model, but not in the porcine model. In both models, prophylaxis with bacteriophages increased treatment efficacy. In all cases, bacteriophage treatment outperformed fusidic acid treatment. Both models allowed investigation of bacteriophage-bacteria dynamics in burn wounds. Overall, bacteriophage treatment outperformed antibiotic control underlining the potential of bacteriophage therapy for the treatment of burn wound infections, especially when used prophylactically.
{"title":"Bacteriophage therapy reduces <i>Staphylococcus aureus</i> in a porcine and human <i>ex vivo</i> burn wound infection model.","authors":"Michèle M Molendijk, Bouke K H L Boekema, Kirby R Lattwein, Marcel Vlig, Lonneke G M Bode, Marion P G Koopmans, Annelies Verbon, Miranda de Graaf, Willem J B van Wamel","doi":"10.1128/aac.00650-24","DOIUrl":"10.1128/aac.00650-24","url":null,"abstract":"<p><p>Burn wounds are a major burden, with high mortality rates due to infections. <i>Staphylococcus aureus</i> is a major causative agent of burn wound infections, which can be difficult to treat because of antibiotic resistance and biofilm formation. An alternative to antibiotics is the use of bacteriophages, viruses that infect and kill bacteria. We investigated the efficacy of bacteriophage therapy for burn wound infections, in both a porcine and a newly developed human <i>ex vivo</i> skin model. In both models, the efficacy of a reference antibiotic treatment (fusidic acid) and bacteriophage treatment was determined for a single treatment, successive treatment, and prophylaxis. Both models showed a reduction in bacterial load after a single bacteriophage treatment. Increasing the frequency of bacteriophage treatments increased bacteriophage efficacy in the human <i>ex vivo</i> skin model, but not in the porcine model. In both models, prophylaxis with bacteriophages increased treatment efficacy. In all cases, bacteriophage treatment outperformed fusidic acid treatment. Both models allowed investigation of bacteriophage-bacteria dynamics in burn wounds. Overall, bacteriophage treatment outperformed antibiotic control underlining the potential of bacteriophage therapy for the treatment of burn wound infections, especially when used prophylactically.</p>","PeriodicalId":8152,"journal":{"name":"Antimicrobial Agents and Chemotherapy","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11373223/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141970511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-04Epub Date: 2024-08-12DOI: 10.1128/aac.00969-24
Isa Faghihi, Victoria C Yan
{"title":"Clinical pharmacodynamics of obeldesivir versus remdesivir.","authors":"Isa Faghihi, Victoria C Yan","doi":"10.1128/aac.00969-24","DOIUrl":"10.1128/aac.00969-24","url":null,"abstract":"","PeriodicalId":8152,"journal":{"name":"Antimicrobial Agents and Chemotherapy","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11373207/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141915989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-04Epub Date: 2024-08-06DOI: 10.1128/aac.00458-24
Xiaowei Zang, Wendy Ankrom, Walter K Kraft, Ryan Vargo, S Aubrey Stoch, Marian Iwamoto, Randolph P Matthews
Antiretroviral therapy has substantially reduced morbidity, mortality, and disease transmission in people living with HIV. Islatravir is a nucleoside reverse transcriptase translocation inhibitor that inhibits HIV-1 replication by multiple mechanisms of action, and it is in development for the treatment of HIV-1 infection. In preclinical and clinical studies, islatravir had a long half-life (t½) of 3.0 and 8.7 days (72 and 209 hours, respectively); therefore, islatravir is being investigated as a long-acting oral antiretroviral agent. A study was conducted to definitively elucidate the terminal t½ of islatravir and its active form islatravir-triphosphate (islatravir-TP). A single-site, open-label, non-randomized, single-dose phase 1 study was performed to evaluate the pharmacokinetics and safety of islatravir in plasma and the pharmacokinetics of islatravir-TP in peripheral blood mononuclear cells after administration of a single oral dose of islatravir 30 mg. Eligible participants were healthy adult males without HIV infection between the ages of 18 and 65 years. Fourteen participants were enrolled. The median time to maximum plasma islatravir concentration was 1 hour. Plasma islatravir concentrations decreased in a biphasic manner, with a t½ of 73 hours. The t½ (percentage geometric coefficient of variation) of islatravir-TP in peripheral blood mononuclear cells through 6 weeks (~1008 hours) after dosing was 8.1 days or 195 hours (25.6%). Islatravir was generally well tolerated with no drug-related adverse events observed. Islatravir-TP has a long intracellular t½, supporting further clinical investigation of islatravir administered at an extended dosing interval.
{"title":"Intracellular islatravir-triphosphate half-life supports extended dosing intervals.","authors":"Xiaowei Zang, Wendy Ankrom, Walter K Kraft, Ryan Vargo, S Aubrey Stoch, Marian Iwamoto, Randolph P Matthews","doi":"10.1128/aac.00458-24","DOIUrl":"10.1128/aac.00458-24","url":null,"abstract":"<p><p>Antiretroviral therapy has substantially reduced morbidity, mortality, and disease transmission in people living with HIV. Islatravir is a nucleoside reverse transcriptase translocation inhibitor that inhibits HIV-1 replication by multiple mechanisms of action, and it is in development for the treatment of HIV-1 infection. In preclinical and clinical studies, islatravir had a long half-life (t<sub>½</sub>) of 3.0 and 8.7 days (72 and 209 hours, respectively); therefore, islatravir is being investigated as a long-acting oral antiretroviral agent. A study was conducted to definitively elucidate the terminal t<sub>½</sub> of islatravir and its active form islatravir-triphosphate (islatravir-TP). A single-site, open-label, non-randomized, single-dose phase 1 study was performed to evaluate the pharmacokinetics and safety of islatravir in plasma and the pharmacokinetics of islatravir-TP in peripheral blood mononuclear cells after administration of a single oral dose of islatravir 30 mg. Eligible participants were healthy adult males without HIV infection between the ages of 18 and 65 years. Fourteen participants were enrolled. The median time to maximum plasma islatravir concentration was 1 hour. Plasma islatravir concentrations decreased in a biphasic manner, with a t<sub>½</sub> of 73 hours. The t<sub>½</sub> (percentage geometric coefficient of variation) of islatravir-TP in peripheral blood mononuclear cells through 6 weeks (~1008 hours) after dosing was 8.1 days or 195 hours (25.6%). Islatravir was generally well tolerated with no drug-related adverse events observed. Islatravir-TP has a long intracellular t<sub>½</sub>, supporting further clinical investigation of islatravir administered at an extended dosing interval.</p>","PeriodicalId":8152,"journal":{"name":"Antimicrobial Agents and Chemotherapy","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11382622/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141892709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-04Epub Date: 2024-08-13DOI: 10.1128/aac.00369-24
Md Yeunus Mian, Dishary Sharmin, Prithu Mondal, Jawad Bin Belayet, M Mahmun Hossain, Paul McCusker, Kaetlyn T Ryan, Alexander Y Fedorov, Heather A Green, Spencer S Ericksen, Mostafa Zamanian, V V N Phani Babu Tiruveedhula, James M Cook, John D Chan
The neglected tropical disease schistosomiasis infects over 200 million people worldwide and is treated with just one broad-spectrum antiparasitic drug (praziquantel). Alternative drugs are needed in the event of emerging praziquantel resistance or treatment failure. One promising lead that has shown efficacy in animal models and a human clinical trial is the benzodiazepine meclonazepam, discovered by Roche in the 1970s. Meclonazepam was not brought to market because of dose-limiting sedative side effects. However, the human target of meclonazepam that causes sedation (GABAARs) is not orthologous to the parasite targets that cause worm death. Therefore, we were interested in whether the structure of meclonazepam could be modified to produce antiparasitic benzodiazepines that do not cause host sedation. We synthesized 18 meclonazepam derivatives with modifications at different positions on the benzodiazepine ring system and tested them for in vitro antiparasitic activity. This identified five compounds that progressed to in vivo screening in a murine model, two of which cured parasite infections with comparable potency to meclonazepam. When these two compounds were administered to mice that were run on the rotarod test, both were less sedating than meclonazepam. These findings demonstrate the proof of concept that meclonazepam analogs can be designed with an improved therapeutic index and point to the C3 position of the benzodiazepine ring system as a logical site for further structure-activity exploration to further optimize this chemical series.
{"title":"Development of non-sedating benzodiazepines with <i>in vivo</i> antischistosomal activity.","authors":"Md Yeunus Mian, Dishary Sharmin, Prithu Mondal, Jawad Bin Belayet, M Mahmun Hossain, Paul McCusker, Kaetlyn T Ryan, Alexander Y Fedorov, Heather A Green, Spencer S Ericksen, Mostafa Zamanian, V V N Phani Babu Tiruveedhula, James M Cook, John D Chan","doi":"10.1128/aac.00369-24","DOIUrl":"10.1128/aac.00369-24","url":null,"abstract":"<p><p>The neglected tropical disease schistosomiasis infects over 200 million people worldwide and is treated with just one broad-spectrum antiparasitic drug (praziquantel). Alternative drugs are needed in the event of emerging praziquantel resistance or treatment failure. One promising lead that has shown efficacy in animal models and a human clinical trial is the benzodiazepine meclonazepam, discovered by Roche in the 1970s. Meclonazepam was not brought to market because of dose-limiting sedative side effects. However, the human target of meclonazepam that causes sedation (GABA<sub>A</sub>Rs) is not orthologous to the parasite targets that cause worm death. Therefore, we were interested in whether the structure of meclonazepam could be modified to produce antiparasitic benzodiazepines that do not cause host sedation. We synthesized 18 meclonazepam derivatives with modifications at different positions on the benzodiazepine ring system and tested them for <i>in vitro</i> antiparasitic activity. This identified five compounds that progressed to <i>in vivo</i> screening in a murine model, two of which cured parasite infections with comparable potency to meclonazepam. When these two compounds were administered to mice that were run on the rotarod test, both were less sedating than meclonazepam. These findings demonstrate the proof of concept that meclonazepam analogs can be designed with an improved therapeutic index and point to the C3 position of the benzodiazepine ring system as a logical site for further structure-activity exploration to further optimize this chemical series.</p>","PeriodicalId":8152,"journal":{"name":"Antimicrobial Agents and Chemotherapy","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11373208/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141970512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-04Epub Date: 2024-08-12DOI: 10.1128/aac.00272-24
Caitlyn M Rotondo, Gerard D Wright
The effectiveness of β-lactam antibiotics is increasingly threatened by resistant bacteria that harbor hydrolytic β-lactamase enzymes. Depending on the class of β-lactamase present, β-lactam hydrolysis can occur through one of two general molecular mechanisms. Metallo-β-lactamases (MBLs) require active site Zn2+ ions, whereas serine-β-lactamases (SBLs) deploy a catalytic serine residue. The result in both cases is drug inactivation via the opening of the β-lactam warhead of the antibiotic. MBLs confer resistance to most β-lactams and are non-susceptible to SBL inhibitors, including recently approved diazabicyclooctanes, such as avibactam; consequently, these enzymes represent a growing threat to public health. Aspergillomarasmine A (AMA), a fungal natural product, can rescue the activity of the β-lactam antibiotic meropenem against MBL-expressing bacterial strains. However, the effectiveness of this β-lactam/β-lactamase inhibitor combination against bacteria producing multiple β-lactamases remains unknown. We systematically investigated the efficacy of AMA/meropenem combination therapy with and without avibactam against 10 Escherichia coli and 10 Klebsiella pneumoniae laboratory strains tandemly expressing single MBL and SBL enzymes. Cell-based assays demonstrated that laboratory strains producing NDM-1 and KPC-2 carbapenemases were resistant to the AMA/meropenem combination but became drug-susceptible upon adding avibactam. We also probed these combinations against 30 clinical isolates expressing multiple β-lactamases. E. coli, Enterobacter cloacae, and K. pneumoniae clinical isolates were more susceptible to AMA, avibactam, and meropenem than Pseudomonas aeruginosa and Acinetobacter baumannii isolates. Overall, the results demonstrate that a triple combination of AMA/avibactam/meropenem has potential for empirical treatment of infections caused by multiple β-lactamase-producing bacteria, especially Enterobacterales.
{"title":"Efficacy of aspergillomarasmine A/meropenem combinations with and without avibactam against bacterial strains producing multiple β-lactamases.","authors":"Caitlyn M Rotondo, Gerard D Wright","doi":"10.1128/aac.00272-24","DOIUrl":"10.1128/aac.00272-24","url":null,"abstract":"<p><p>The effectiveness of β-lactam antibiotics is increasingly threatened by resistant bacteria that harbor hydrolytic β-lactamase enzymes. Depending on the class of β-lactamase present, β-lactam hydrolysis can occur through one of two general molecular mechanisms. Metallo-β-lactamases (MBLs) require active site Zn<sup>2+</sup> ions, whereas serine-β-lactamases (SBLs) deploy a catalytic serine residue. The result in both cases is drug inactivation via the opening of the β-lactam warhead of the antibiotic. MBLs confer resistance to most β-lactams and are non-susceptible to SBL inhibitors, including recently approved diazabicyclooctanes, such as avibactam; consequently, these enzymes represent a growing threat to public health. Aspergillomarasmine A (AMA), a fungal natural product, can rescue the activity of the β-lactam antibiotic meropenem against MBL-expressing bacterial strains. However, the effectiveness of this β-lactam/β-lactamase inhibitor combination against bacteria producing multiple β-lactamases remains unknown. We systematically investigated the efficacy of AMA/meropenem combination therapy with and without avibactam against 10 <i>Escherichia coli</i> and 10 <i>Klebsiella pneumoniae</i> laboratory strains tandemly expressing single MBL and SBL enzymes. Cell-based assays demonstrated that laboratory strains producing NDM-1 and KPC-2 carbapenemases were resistant to the AMA/meropenem combination but became drug-susceptible upon adding avibactam. We also probed these combinations against 30 clinical isolates expressing multiple β-lactamases. <i>E. coli</i>, <i>Enterobacter cloacae,</i> and <i>K. pneumoniae</i> clinical isolates were more susceptible to AMA, avibactam, and meropenem than <i>Pseudomonas aeruginosa</i> and <i>Acinetobacter baumannii</i> isolates. Overall, the results demonstrate that a triple combination of AMA/avibactam/meropenem has potential for empirical treatment of infections caused by multiple β-lactamase-producing bacteria, especially Enterobacterales.</p>","PeriodicalId":8152,"journal":{"name":"Antimicrobial Agents and Chemotherapy","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11373191/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141915990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-04Epub Date: 2024-07-26DOI: 10.1128/aac.00555-24
Madison E Nelson, Jaime L Little, Christopher J Kristich
Enterococci exhibit intrinsic resistance to cephalosporins, mediated in part by the class B penicillin-binding protein (bPBP) Pbp4 that exhibits low reactivity toward cephalosporins and thus can continue crosslinking peptidoglycan despite exposure to cephalosporins. bPBPs partner with cognate SEDS (shape, elongation, division, and sporulation) glycosyltransferases to form the core catalytic complex of peptidoglycan synthases that synthesize peptidoglycan at discrete cellular locations, although the SEDS partner for Pbp4 is unknown. SEDS-bPBP peptidoglycan synthases of enterococci have not been studied, but some SEDS-bPBP pairs can be predicted based on sequence similarity. For example, FtsW (SEDS)-PbpB (bPBP) is predicted to form the catalytic core of the peptidoglycan synthase that functions at the division septum (the divisome). However, PbpB is readily inactivated by cephalosporins, raising the question-how could the FtsW-PbpB synthase continue functioning to enable growth in the presence of cephalosporins? In this work, we report that the FtsW-PbpB peptidoglycan synthase is required for cephalosporin resistance of Enterococcus faecalis, despite the fact that PbpB is inactivated by cephalosporins. Moreover, Pbp4 associates with the FtsW-PbpB synthase and the TPase activity of Pbp4 is required to enable growth in the presence of cephalosporins in an FtsW-PbpB-synthase-dependent manner. Overall, our results implicate a model in which Pbp4 directly interacts with the FtsW-PbpB peptidoglycan synthase to provide TPase activity during cephalosporin treatment, thereby maintaining the divisome SEDS-bPBP peptidoglycan synthase in a functional state competent to synthesize crosslinked peptidoglycan. These results suggest that two bPBPs coordinate within the FtsW-PbpB peptidoglycan synthase to drive cephalosporin resistance in E. faecalis.
{"title":"Pbp4 provides transpeptidase activity to the FtsW-PbpB peptidoglycan synthase to drive cephalosporin resistance in <i>Enterococcus faecalis</i>.","authors":"Madison E Nelson, Jaime L Little, Christopher J Kristich","doi":"10.1128/aac.00555-24","DOIUrl":"10.1128/aac.00555-24","url":null,"abstract":"<p><p>Enterococci exhibit intrinsic resistance to cephalosporins, mediated in part by the class B penicillin-binding protein (bPBP) Pbp4 that exhibits low reactivity toward cephalosporins and thus can continue crosslinking peptidoglycan despite exposure to cephalosporins. bPBPs partner with cognate SEDS (shape, elongation, division, and sporulation) glycosyltransferases to form the core catalytic complex of peptidoglycan synthases that synthesize peptidoglycan at discrete cellular locations, although the SEDS partner for Pbp4 is unknown. SEDS-bPBP peptidoglycan synthases of enterococci have not been studied, but some SEDS-bPBP pairs can be predicted based on sequence similarity. For example, FtsW (SEDS)-PbpB (bPBP) is predicted to form the catalytic core of the peptidoglycan synthase that functions at the division septum (the divisome). However, PbpB is readily inactivated by cephalosporins, raising the question-how could the FtsW-PbpB synthase continue functioning to enable growth in the presence of cephalosporins? In this work, we report that the FtsW-PbpB peptidoglycan synthase is required for cephalosporin resistance of <i>Enterococcus faecalis</i>, despite the fact that PbpB is inactivated by cephalosporins. Moreover, Pbp4 associates with the FtsW-PbpB synthase and the TPase activity of Pbp4 is required to enable growth in the presence of cephalosporins in an FtsW-PbpB-synthase-dependent manner. Overall, our results implicate a model in which Pbp4 directly interacts with the FtsW-PbpB peptidoglycan synthase to provide TPase activity during cephalosporin treatment, thereby maintaining the divisome SEDS-bPBP peptidoglycan synthase in a functional state competent to synthesize crosslinked peptidoglycan. These results suggest that two bPBPs coordinate within the FtsW-PbpB peptidoglycan synthase to drive cephalosporin resistance in <i>E. faecalis</i>.</p>","PeriodicalId":8152,"journal":{"name":"Antimicrobial Agents and Chemotherapy","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11373202/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141756772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-04Epub Date: 2024-08-13DOI: 10.1128/aac.00863-24
Meg K Tully, Saber Dini, Jennifer A Flegg, James S McCarthy, David J Price, Julie A Simpson
The rise of multidrug-resistant malaria requires accelerated development of novel antimalarial drugs. Pharmacokinetic-pharmacodynamic (PK-PD) models relate blood antimalarial drug concentrations with the parasite-time profile to inform dosing regimens. We performed a simulation study to assess the utility of a Bayesian hierarchical mechanistic PK-PD model for predicting parasite-time profiles for a Phase 2 study of a new antimalarial drug, cipargamin. We simulated cipargamin concentration- and malaria parasite-profiles based on a Phase 2 study of eight volunteers who received cipargamin 7 days after inoculation with malaria parasites. The cipargamin profiles were generated from a two-compartment PK model and parasite profiles from a previously published biologically informed PD model. One thousand PK-PD data sets of eight patients were simulated, following the sampling intervals of the Phase 2 study. The mechanistic PK-PD model was incorporated in a Bayesian hierarchical framework, and the parameters were estimated. Population PK model parameters describing absorption, distribution, and clearance were estimated with minimal bias (mean relative bias ranged from 1.7% to 8.4%). The PD model was fitted to the parasitaemia profiles in each simulated data set using the estimated PK parameters. Posterior predictive checks demonstrate that our PK-PD model adequately captures the simulated PD profiles. The bias of the estimated population average PD parameters was low-moderate in magnitude. This simulation study demonstrates the viability of our PK-PD model to predict parasitological outcomes in Phase 2 volunteer infection studies. This work will inform the dose-effect relationship of cipargamin, guiding decisions on dosing regimens to be evaluated in Phase 3 trials.
{"title":"Evaluation of a Bayesian hierarchical pharmacokinetic-pharmacodynamic model for predicting parasitological outcomes in Phase 2 studies of new antimalarial drugs.","authors":"Meg K Tully, Saber Dini, Jennifer A Flegg, James S McCarthy, David J Price, Julie A Simpson","doi":"10.1128/aac.00863-24","DOIUrl":"10.1128/aac.00863-24","url":null,"abstract":"<p><p>The rise of multidrug-resistant malaria requires accelerated development of novel antimalarial drugs. Pharmacokinetic-pharmacodynamic (PK-PD) models relate blood antimalarial drug concentrations with the parasite-time profile to inform dosing regimens. We performed a simulation study to assess the utility of a Bayesian hierarchical mechanistic PK-PD model for predicting parasite-time profiles for a Phase 2 study of a new antimalarial drug, cipargamin. We simulated cipargamin concentration- and malaria parasite-profiles based on a Phase 2 study of eight volunteers who received cipargamin 7 days after inoculation with malaria parasites. The cipargamin profiles were generated from a two-compartment PK model and parasite profiles from a previously published biologically informed PD model. One thousand PK-PD data sets of eight patients were simulated, following the sampling intervals of the Phase 2 study. The mechanistic PK-PD model was incorporated in a Bayesian hierarchical framework, and the parameters were estimated. Population PK model parameters describing absorption, distribution, and clearance were estimated with minimal bias (mean relative bias ranged from 1.7% to 8.4%). The PD model was fitted to the parasitaemia profiles in each simulated data set using the estimated PK parameters. Posterior predictive checks demonstrate that our PK-PD model adequately captures the simulated PD profiles. The bias of the estimated population average PD parameters was low-moderate in magnitude. This simulation study demonstrates the viability of our PK-PD model to predict parasitological outcomes in Phase 2 volunteer infection studies. This work will inform the dose-effect relationship of cipargamin, guiding decisions on dosing regimens to be evaluated in Phase 3 trials.</p>","PeriodicalId":8152,"journal":{"name":"Antimicrobial Agents and Chemotherapy","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11373224/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141970513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-04Epub Date: 2024-07-29DOI: 10.1128/aac.00235-24
Geeta Ram, LiTing Chiu, Somrita Dey, Hope F Ross, Michael Cammer, Richard P Novick
In response to the antimicrobial resistance crisis, we have developed a powerful and versatile therapeutic platform, the Antibacterial Drone (ABD) system. The ABD consists of a highly mobile staphylococcal pathogenicity island re-purposed to deliver genes encoding antibacterial proteins. The chromosomally located island is induced by a co-resident helper phage, packaged in phage-like particles, and released in very high numbers upon phage-induced lysis. ABD particles specifically adsorb to bacteria causing an infection and deliver their DNA to these bacteria, where the bactericidal cargo genes are expressed, kill the bacteria, and cure the infection. Here, we report a major advance of the system, incorporation of the gene encoding a secreted, bactericidal, species-specific lytic enzyme, lysostsphin. This ABD not only kills the bacterium that has been attacked by the ABD, but also any surrounding bacteria that are sensitive to the lytic enzyme which is released by secretion and by lysis of the doomed cell. So while the killing field is thus expanded, there are no civilian casualties (bacteria that are insensitive to the ABD and its cargo protein(s) are not inadvertently killed). Without amplifying the number of ABD particles (which are not re-packaged), the expression and release of the cargo gene's product dramatically extend the effective reach of the ABD. A cargo gene that encodes a secreted bactericidal protein also enables the treatment of a mixed bacterial infection in which one of the infecting organisms is insensitive to the ABD delivery system but is sensitive to the ABD's secreted cargo protein.
为了应对抗菌药耐药性危机,我们开发了一个功能强大、用途广泛的治疗平台--抗菌无人机(ABD)系统。ABD 由一个高移动性的葡萄球菌致病性岛组成,它被重新用于传递编码抗菌蛋白的基因。位于染色体上的致病岛由共驻辅助噬菌体诱导,包装在噬菌体样颗粒中,并在噬菌体诱导裂解时大量释放。ABD 颗粒特异性地吸附在引起感染的细菌上,并将其 DNA 传递给这些细菌,在这些细菌上表达杀菌货载基因,杀死细菌,治愈感染。在这里,我们报告了该系统的一大进步,即加入了编码分泌型、杀菌型、物种特异性溶菌酶--溶菌酶的基因。这种 ABD 不仅能杀死被 ABD 攻击的细菌,还能杀死周围任何对溶菌酶敏感的细菌。因此,虽然杀伤范围扩大了,但却不会造成平民伤亡(对 ABD 及其载体蛋白不敏感的细菌不会在无意中被杀死)。在不增加 ABD 粒子数量(不会重新包装)的情况下,货物基因产物的表达和释放大大扩展了 ABD 的有效范围。编码分泌型杀菌蛋白的载货基因还能治疗混合细菌感染,其中一种感染生物对 ABD 运载系统不敏感,但对 ABD 的分泌型载货蛋白敏感。
{"title":"ABD-3, the confluence of powerful antibacterial modalities: ABDs delivering and expressing <i>ls</i>s, the gene encoding lysostaphin.","authors":"Geeta Ram, LiTing Chiu, Somrita Dey, Hope F Ross, Michael Cammer, Richard P Novick","doi":"10.1128/aac.00235-24","DOIUrl":"10.1128/aac.00235-24","url":null,"abstract":"<p><p>In response to the antimicrobial resistance crisis, we have developed a powerful and versatile therapeutic platform, the Antibacterial Drone (ABD) system. The ABD consists of a highly mobile staphylococcal pathogenicity island re-purposed to deliver genes encoding antibacterial proteins. The chromosomally located island is induced by a co-resident helper phage, packaged in phage-like particles, and released in very high numbers upon phage-induced lysis. ABD particles specifically adsorb to bacteria causing an infection and deliver their DNA to these bacteria, where the bactericidal cargo genes are expressed, kill the bacteria, and cure the infection. Here, we report a major advance of the system, incorporation of the gene encoding a secreted, bactericidal, species-specific lytic enzyme, lysostsphin. This ABD not only kills the bacterium that has been attacked by the ABD, but also any surrounding bacteria that are sensitive to the lytic enzyme which is released by secretion and by lysis of the doomed cell. So while the killing field is thus expanded, there are no civilian casualties (bacteria that are insensitive to the ABD and its cargo protein(s) are not inadvertently killed). Without amplifying the number of ABD particles (which are not re-packaged), the expression and release of the cargo gene's product dramatically extend the effective reach of the ABD. A cargo gene that encodes a secreted bactericidal protein also enables the treatment of a mixed bacterial infection in which one of the infecting organisms is insensitive to the ABD delivery system but is sensitive to the ABD's secreted cargo protein.</p>","PeriodicalId":8152,"journal":{"name":"Antimicrobial Agents and Chemotherapy","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11373205/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141787107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Escherichia coli ST131 is a multidrug-resistant lineage associated with the global spread of extended-spectrum β-lactamase-producing organisms. Particularly, ST131 clade C1 is the most predominant clade in Japan, harboring blaCTX-M-14 at a high frequency. However, the process of resistance gene acquisition and spread remains unclear. Here, we performed whole-genome sequencing of 19 E. coli strains belonging to 12 STs and 12 fimH types collected between 1997 and 2016. Additionally, we analyzed the full-length genome sequences of 96 ST131-H30 clade C0 and C1 strains, including those obtained from this study and those registered in public databases, to understand how ST131 clade C1 acquired and spread blaCTX-M-14. We detected conjugative IncFII plasmids and IncB/O/K/Z plasmids carrying blaCTX-M-14 in diverse genetic lineages of E. coli strains from the 1990s to the 2010s, suggesting that these plasmids played an important role in the spread of blaCTX-M-14. Molecular phylogenetic and molecular clock analyses of the 96 ST131-H30 clade C0 and C1 strains identified 8 subclades. Strains harboring blaCTX-M-14 were clustered in subclades 4 and 5, and it was inferred that clade C1 acquired blaCTX-M-14 around 1993. All 34 strains belonging to subclade 5 possessed blaCTX-M-14 with ISEcp1 upstream at the same chromosomal position, indicating their common ancestor acquired blaCTX-M-14 in a single ISEcp1-mediated transposition event during the early formation of the subclade around 1999. Therefore, both the horizontal transfer of plasmids carrying blaCTX-M-14 to diverse genetic lineages and chromosomal integration in the predominant genetic lineage have contributed to the spread of blaCTX-M-14.
{"title":"Plasmid-mediated acquisition and chromosomal integration of <i>bla</i><sub>CTX-M-14</sub> in a subclade of <i>Escherichia coli</i> ST131-<i>H</i>30 clade C1.","authors":"Kohji Komori, Kotaro Aoki, Sohei Harada, Yoshikazu Ishii, Kazuhiro Tateda","doi":"10.1128/aac.00817-24","DOIUrl":"10.1128/aac.00817-24","url":null,"abstract":"<p><p><i>Escherichia coli</i> ST131 is a multidrug-resistant lineage associated with the global spread of extended-spectrum β-lactamase-producing organisms. Particularly, ST131 clade C1 is the most predominant clade in Japan, harboring <i>bla</i><sub>CTX-M-14</sub> at a high frequency. However, the process of resistance gene acquisition and spread remains unclear. Here, we performed whole-genome sequencing of 19 <i>E. coli</i> strains belonging to 12 STs and 12 <i>fimH</i> types collected between 1997 and 2016. Additionally, we analyzed the full-length genome sequences of 96 ST131-<i>H</i>30 clade C0 and C1 strains, including those obtained from this study and those registered in public databases, to understand how ST131 clade C1 acquired and spread <i>bla</i><sub>CTX-M-14</sub>. We detected conjugative IncFII plasmids and IncB/O/K/Z plasmids carrying <i>bla</i><sub>CTX-M-14</sub> in diverse genetic lineages of <i>E. coli</i> strains from the 1990s to the 2010s, suggesting that these plasmids played an important role in the spread of <i>bla</i><sub>CTX-M-14</sub>. Molecular phylogenetic and molecular clock analyses of the 96 ST131-<i>H</i>30 clade C0 and C1 strains identified 8 subclades. Strains harboring <i>bla</i><sub>CTX-M-14</sub> were clustered in subclades 4 and 5, and it was inferred that clade C1 acquired <i>bla</i><sub>CTX-M-14</sub> around 1993. All 34 strains belonging to subclade 5 possessed <i>bla</i><sub>CTX-M-14</sub> with IS<i>Ecp1</i> upstream at the same chromosomal position, indicating their common ancestor acquired <i>bla</i><sub>CTX-M-14</sub> in a single IS<i>Ecp1</i>-mediated transposition event during the early formation of the subclade around 1999. Therefore, both the horizontal transfer of plasmids carrying <i>bla</i><sub>CTX-M-14</sub> to diverse genetic lineages and chromosomal integration in the predominant genetic lineage have contributed to the spread of <i>bla</i><sub>CTX-M-14</sub>.</p>","PeriodicalId":8152,"journal":{"name":"Antimicrobial Agents and Chemotherapy","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11373201/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141915992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}