Patterns of carbohydrates and determination of API ZYM and API oxidases can be considered a usefu... more Patterns of carbohydrates and determination of API ZYM and API oxidases can be considered a useful way to differentiate the strains of Listeria. With all this information it is possible to work out a schematic table that allows the identification of Listeria strains with a remarkable certainty. By numerical analysis four differentiated clusters have been demonstrated.
Journal of Antimicrobial Chemotherapy, Oct 21, 2020
BackgroundThe development of resistance to ceftolozane/tazobactam and ceftazidime/avibactam durin... more BackgroundThe development of resistance to ceftolozane/tazobactam and ceftazidime/avibactam during treatment of Pseudomonas aeruginosa infections is concerning.ObjectivesCharacterization of the mechanisms leading to the development of OXA-10-mediated resistance to ceftolozane/tazobactam and ceftazidime/avibactam during treatment of XDR P. aeruginosa infections.MethodsFour paired ceftolozane/tazobactam- and ceftazidime/avibactam-susceptible/resistant isolates were evaluated. MICs were determined by broth microdilution. STs, resistance mechanisms and genetic context of β-lactamases were determined by genotypic methods, including WGS. The OXA-10 variants were cloned in PAO1 to assess their impact on resistance. Models for the OXA-10 derivatives were constructed to evaluate the structural impact of the amino acid changes.ResultsThe same XDR ST253 P. aeruginosa clone was detected in all four cases evaluated. All initial isolates showed OprD deficiency, produced an OXA-10 enzyme and were susceptible to ceftazidime, ceftolozane/tazobactam, ceftazidime/avibactam and colistin. During treatment, the isolates developed resistance to all cephalosporins. Comparative genomic analysis revealed that the evolved resistant isolates had acquired mutations in the OXA-10 enzyme: OXA-14 (Gly157Asp), OXA-794 (Trp154Cys), OXA-795 (ΔPhe153-Trp154) and OXA-824 (Asn143Lys). PAO1 transformants producing the evolved OXA-10 derivatives showed enhanced ceftolozane/tazobactam and ceftazidime/avibactam resistance but decreased meropenem MICs in a PAO1 background. Imipenem/relebactam retained activity against all strains. Homology models revealed important changes in regions adjacent to the active site of the OXA-10 enzyme. The blaOXA-10 gene was plasmid borne and acquired due to transposition of Tn6746 in the pHUPM plasmid scaffold.ConclusionsModification of OXA-10 is a mechanism involved in the in vivo acquisition of resistance to cephalosporin/β-lactamase inhibitor combinations in P. aeruginosa.
Journal of Antimicrobial Chemotherapy, Mar 15, 2023
Objectives To describe and characterize the emergence of resistance to ceftolozane/tazobactam, ce... more Objectives To describe and characterize the emergence of resistance to ceftolozane/tazobactam, ceftazidime/avibactam and imipenem/relebactam in a patient receiving ceftazidime/avibactam treatment for an MDR Pseudomonas aeruginosa CNS infection. Methods One baseline (PA1) and two post-exposure (PA2 and PA3) isolates obtained before and during treatment of a nosocomial P. aeruginosa meningoventriculitis were evaluated. MICs were determined by broth microdilution. Mutational changes were investigated through WGS. The impact on β-lactam resistance of mutations in blaPDC and mexR was determined through cloning experiments and complementation assays. Results Isolate PA1 showed baseline resistance mutations in DacB (I354A) and OprD (N142fs) conferring resistance to conventional antipseudomonals but susceptibility to ceftazidime/avibactam, ceftolozane/tazobactam and imipenem/relebactam. Post-exposure isolates showed two divergent ceftazidime/avibactam-resistant phenotypes associated with distinctive mutations affecting the intrinsic P PDC β-lactamase (S254Ins) (PA2: ceftolozane/tazobactam and ceftazidime/avibactam-resistant) or MexAB-OprM negative regulator MexR in combination with modification of PBP3 (PA3: ceftazidime/avibactam and imipenem/relebactam-relebactam-resistant). Cloning experiments demonstrated the role of PDC modification in resistance to ceftolozane/tazobactam and ceftazidime/avibactam. Complementation with a functional copy of the mexR gene in isolate PA3 restored imipenem/relebactam susceptibility. Conclusions We demonstrated how P. aeruginosa may simultaneously develop resistance and compromise the activity of new β-lactam/β-lactamase inhibitor combinations when exposed to ceftazidime/avibactam through selection of mutations leading to PDC modification and up-regulation of MexAB-OprM-mediated efflux.
BACKGROUND AND AIMSThe poor humoral response after vaccination against SARS-CoV-2 in kidney trans... more BACKGROUND AND AIMSThe poor humoral response after vaccination against SARS-CoV-2 in kidney transplant (KT) patients led to the approval of a third dose. Recent data show an increase in the antibody titer, although lower than in the general population. Our aim is to analyze the humoral immune response after the third dose a mRNA vaccine against SARS-CoV-2 and the evolution of the antispike antibody (antiS) titers in KT recipients.METHODWe performed a prospective cohort study of stable KT patients from our center who received three doses of a mRNA vaccine from March to November 2021. KT recipients with less than 6 months after transplantation and with active oncological or hematologic disease were excluded. We determined antiS titers (Abbott SARS‐CoV‐2 IgG chemiluminescent microparticle immunoassay) at baseline, one month after the second dose and one month after the third one. We compared those KT patients who seroconverted with 2 and with 3 doses of vaccine and those who did not seroconvert. To identify risk factors for no seroconversion, a logistic regression analysis was carried out.RESULTSWe included 83 KT. Mean age was 59.3 years and 62.7% were male. The median time from KT to the first vaccine dose was 94 months and between the second and third dose median time was 4 months. Seroconversion rate was 63.8% after 2 doses and 85.5% after the third one (P < 0.001). Twelve KT did not develop antibodies (Table 1). Patients who did not seroconvert were older (P = 0.047), had a worse renal function (P = 0.009) and had fewer lymphocytes than those that developed antibodies (0.013). Besides, they almost half of them received a KT from a non-heart-beating donor (P = 0.026) and were treated with thymoglobulin in the 2 years prior to the vaccine more frequently (P = 0.007). In patients who seroconverted after 2 doses, we observed a 10-fold increase in the antiS titer after the third vaccine (82 [34–350] UI/mL versus 814 [205–2415] UI/mL; P < 0.001). No patients had neither acute rejection nor serious adverse effects. In the multivariable analysis advanced age, a worse kidney function and recent treatment with thymoglobulin were risk factors for no seroconversion (Table 1). Open in a separate window Open in a separate windowCONCLUSIONThe third dose of a mRNA vaccine against SARS-CoV-2 significantly increased the seroconversion rate and the antiS titers in stable KT patients. Advanced age, poorer kidney function and immunosuppressive treatment are risk factors for no seroconversion.
Quarterly Journal of Nuclear Medicine and Molecular Imaging, Sep 1, 2021
BACKGROUND The aim of this study was to ascertain whether the extemporaneous technetium-99m radio... more BACKGROUND The aim of this study was to ascertain whether the extemporaneous technetium-99m radiopharmaceuticals -prepared by closed procedures- maintain or not sterility throughout their lifespan regardless the quality of the environmental air where they are prepared, stored and dispensed, provided that the basic aseptic rules for closed procedures are followed. METHODS Three different types of assays were performed in this study: 1) sterility tests of each and every one of the vials with the remains of technetium-99m radiopharmaceuticals, which have been prepared in our hospital radiopharmacy during three years without any special environmental air conditions; 2) integrity tests of punctured rubber plug closures using both microbial challenge testing and dye ingress testing; and 3) simulation of the dispensing process using a liquid growth medium. RESULTS Sterility tests of more than 6,000 vials with the remains of technetium-99m radiopharmaceuticals -prepared without any special ambient air conditions- were performed, all of them with a negative result (no growth of microorganisms occurs). The integrity of punctured rubber plugs closure was sufficiently proven under extreme conditions by two different methods. The maintenance of sterility during the dispensing process of technetium-99m radiopharmaceuticals was also proven by simulation of the dispensing process using a liquid growth medium. CONCLUSIONS This study strongly supports that it is not necessary any special ambient air conditions to prepare, store and dispense extemporaneous technetium-99m radiopharmaceuticals in order to preserve their sterility when the basic aseptic rules for closed procedures are followed.
Introduction: Scopulariopsis is a common soil saprophyte. In the last years the infections caused... more Introduction: Scopulariopsis is a common soil saprophyte. In the last years the infections caused by Scopulariopsis species have increased, included superficial and invasive mycoses. This fungi has been reported resistant in vitro to some antifungal agents, although there is little information about this. The aim of the study was to establish in vitro antifungal susceptibility of clinical isolates of Scopulariopsis species against to broad-spectrum antifungal agents. Methods: A total of 28 Scopulariopsis strains (10 S. brevicaulis, 7 S. koningii, 3 S. acremonium, 3 S. candida, 3 S. flava, 1 S. brumptii and 1 S. fusca) were tested using Sensititre Yeast One and broth microdilution methods to determine the minimum inhibitory concentrations (MICs) to amphotericin B, fluconazole, itraconazole, posaconazole, voriconazole and 5-fluorocytosine, and minimun effective concentration (MECs) to anidulafungin, caspofungin and micafungin. Results: Our data confirm the high in vitro resistance of Scopulariopsis to antifungal agents. Anidulafungin, caspofungin, micafungin (MICs ≥ 8 mg/L), 5-fluorocytosine (MICs ≥ 64 mg/L), and fluconazole (MICs ≥ 128 mg/L) were inactive in vitro in all species. MICs of amphotericin B (range 2 to ≥ 8 mg/L) and itraconazole (0.5 to ≥ 16 mg/L) were high. The best antifungal activity was observed for posaconazole and voriconazole (0.5 to ≥ 8 mg/L). With Sensititre Yeast One method MICs obtained slightly lower. Scopulariopsis candida, S. flava and S. fusca were the most resistant species, while S. acremonium and S. brevicaulis showed the lowest MICs. Conclusions: MICs of all tested antifungal agents for Scopulariopsis were very high. Infections caused by Scopulariopsis species may not respond to antifungal treatment. Voriconazole is the drug of choice for treatment. We consider it appropriate to add amphotericin B in serious infections.
Patterns of carbohydrates and determination of API ZYM and API oxidases can be considered a usefu... more Patterns of carbohydrates and determination of API ZYM and API oxidases can be considered a useful way to differentiate the strains of Listeria. With all this information it is possible to work out a schematic table that allows the identification of Listeria strains with a remarkable certainty. By numerical analysis four differentiated clusters have been demonstrated.
Journal of Antimicrobial Chemotherapy, Oct 21, 2020
BackgroundThe development of resistance to ceftolozane/tazobactam and ceftazidime/avibactam durin... more BackgroundThe development of resistance to ceftolozane/tazobactam and ceftazidime/avibactam during treatment of Pseudomonas aeruginosa infections is concerning.ObjectivesCharacterization of the mechanisms leading to the development of OXA-10-mediated resistance to ceftolozane/tazobactam and ceftazidime/avibactam during treatment of XDR P. aeruginosa infections.MethodsFour paired ceftolozane/tazobactam- and ceftazidime/avibactam-susceptible/resistant isolates were evaluated. MICs were determined by broth microdilution. STs, resistance mechanisms and genetic context of β-lactamases were determined by genotypic methods, including WGS. The OXA-10 variants were cloned in PAO1 to assess their impact on resistance. Models for the OXA-10 derivatives were constructed to evaluate the structural impact of the amino acid changes.ResultsThe same XDR ST253 P. aeruginosa clone was detected in all four cases evaluated. All initial isolates showed OprD deficiency, produced an OXA-10 enzyme and were susceptible to ceftazidime, ceftolozane/tazobactam, ceftazidime/avibactam and colistin. During treatment, the isolates developed resistance to all cephalosporins. Comparative genomic analysis revealed that the evolved resistant isolates had acquired mutations in the OXA-10 enzyme: OXA-14 (Gly157Asp), OXA-794 (Trp154Cys), OXA-795 (ΔPhe153-Trp154) and OXA-824 (Asn143Lys). PAO1 transformants producing the evolved OXA-10 derivatives showed enhanced ceftolozane/tazobactam and ceftazidime/avibactam resistance but decreased meropenem MICs in a PAO1 background. Imipenem/relebactam retained activity against all strains. Homology models revealed important changes in regions adjacent to the active site of the OXA-10 enzyme. The blaOXA-10 gene was plasmid borne and acquired due to transposition of Tn6746 in the pHUPM plasmid scaffold.ConclusionsModification of OXA-10 is a mechanism involved in the in vivo acquisition of resistance to cephalosporin/β-lactamase inhibitor combinations in P. aeruginosa.
Journal of Antimicrobial Chemotherapy, Mar 15, 2023
Objectives To describe and characterize the emergence of resistance to ceftolozane/tazobactam, ce... more Objectives To describe and characterize the emergence of resistance to ceftolozane/tazobactam, ceftazidime/avibactam and imipenem/relebactam in a patient receiving ceftazidime/avibactam treatment for an MDR Pseudomonas aeruginosa CNS infection. Methods One baseline (PA1) and two post-exposure (PA2 and PA3) isolates obtained before and during treatment of a nosocomial P. aeruginosa meningoventriculitis were evaluated. MICs were determined by broth microdilution. Mutational changes were investigated through WGS. The impact on β-lactam resistance of mutations in blaPDC and mexR was determined through cloning experiments and complementation assays. Results Isolate PA1 showed baseline resistance mutations in DacB (I354A) and OprD (N142fs) conferring resistance to conventional antipseudomonals but susceptibility to ceftazidime/avibactam, ceftolozane/tazobactam and imipenem/relebactam. Post-exposure isolates showed two divergent ceftazidime/avibactam-resistant phenotypes associated with distinctive mutations affecting the intrinsic P PDC β-lactamase (S254Ins) (PA2: ceftolozane/tazobactam and ceftazidime/avibactam-resistant) or MexAB-OprM negative regulator MexR in combination with modification of PBP3 (PA3: ceftazidime/avibactam and imipenem/relebactam-relebactam-resistant). Cloning experiments demonstrated the role of PDC modification in resistance to ceftolozane/tazobactam and ceftazidime/avibactam. Complementation with a functional copy of the mexR gene in isolate PA3 restored imipenem/relebactam susceptibility. Conclusions We demonstrated how P. aeruginosa may simultaneously develop resistance and compromise the activity of new β-lactam/β-lactamase inhibitor combinations when exposed to ceftazidime/avibactam through selection of mutations leading to PDC modification and up-regulation of MexAB-OprM-mediated efflux.
BACKGROUND AND AIMSThe poor humoral response after vaccination against SARS-CoV-2 in kidney trans... more BACKGROUND AND AIMSThe poor humoral response after vaccination against SARS-CoV-2 in kidney transplant (KT) patients led to the approval of a third dose. Recent data show an increase in the antibody titer, although lower than in the general population. Our aim is to analyze the humoral immune response after the third dose a mRNA vaccine against SARS-CoV-2 and the evolution of the antispike antibody (antiS) titers in KT recipients.METHODWe performed a prospective cohort study of stable KT patients from our center who received three doses of a mRNA vaccine from March to November 2021. KT recipients with less than 6 months after transplantation and with active oncological or hematologic disease were excluded. We determined antiS titers (Abbott SARS‐CoV‐2 IgG chemiluminescent microparticle immunoassay) at baseline, one month after the second dose and one month after the third one. We compared those KT patients who seroconverted with 2 and with 3 doses of vaccine and those who did not seroconvert. To identify risk factors for no seroconversion, a logistic regression analysis was carried out.RESULTSWe included 83 KT. Mean age was 59.3 years and 62.7% were male. The median time from KT to the first vaccine dose was 94 months and between the second and third dose median time was 4 months. Seroconversion rate was 63.8% after 2 doses and 85.5% after the third one (P < 0.001). Twelve KT did not develop antibodies (Table 1). Patients who did not seroconvert were older (P = 0.047), had a worse renal function (P = 0.009) and had fewer lymphocytes than those that developed antibodies (0.013). Besides, they almost half of them received a KT from a non-heart-beating donor (P = 0.026) and were treated with thymoglobulin in the 2 years prior to the vaccine more frequently (P = 0.007). In patients who seroconverted after 2 doses, we observed a 10-fold increase in the antiS titer after the third vaccine (82 [34–350] UI/mL versus 814 [205–2415] UI/mL; P < 0.001). No patients had neither acute rejection nor serious adverse effects. In the multivariable analysis advanced age, a worse kidney function and recent treatment with thymoglobulin were risk factors for no seroconversion (Table 1). Open in a separate window Open in a separate windowCONCLUSIONThe third dose of a mRNA vaccine against SARS-CoV-2 significantly increased the seroconversion rate and the antiS titers in stable KT patients. Advanced age, poorer kidney function and immunosuppressive treatment are risk factors for no seroconversion.
Quarterly Journal of Nuclear Medicine and Molecular Imaging, Sep 1, 2021
BACKGROUND The aim of this study was to ascertain whether the extemporaneous technetium-99m radio... more BACKGROUND The aim of this study was to ascertain whether the extemporaneous technetium-99m radiopharmaceuticals -prepared by closed procedures- maintain or not sterility throughout their lifespan regardless the quality of the environmental air where they are prepared, stored and dispensed, provided that the basic aseptic rules for closed procedures are followed. METHODS Three different types of assays were performed in this study: 1) sterility tests of each and every one of the vials with the remains of technetium-99m radiopharmaceuticals, which have been prepared in our hospital radiopharmacy during three years without any special environmental air conditions; 2) integrity tests of punctured rubber plug closures using both microbial challenge testing and dye ingress testing; and 3) simulation of the dispensing process using a liquid growth medium. RESULTS Sterility tests of more than 6,000 vials with the remains of technetium-99m radiopharmaceuticals -prepared without any special ambient air conditions- were performed, all of them with a negative result (no growth of microorganisms occurs). The integrity of punctured rubber plugs closure was sufficiently proven under extreme conditions by two different methods. The maintenance of sterility during the dispensing process of technetium-99m radiopharmaceuticals was also proven by simulation of the dispensing process using a liquid growth medium. CONCLUSIONS This study strongly supports that it is not necessary any special ambient air conditions to prepare, store and dispense extemporaneous technetium-99m radiopharmaceuticals in order to preserve their sterility when the basic aseptic rules for closed procedures are followed.
Introduction: Scopulariopsis is a common soil saprophyte. In the last years the infections caused... more Introduction: Scopulariopsis is a common soil saprophyte. In the last years the infections caused by Scopulariopsis species have increased, included superficial and invasive mycoses. This fungi has been reported resistant in vitro to some antifungal agents, although there is little information about this. The aim of the study was to establish in vitro antifungal susceptibility of clinical isolates of Scopulariopsis species against to broad-spectrum antifungal agents. Methods: A total of 28 Scopulariopsis strains (10 S. brevicaulis, 7 S. koningii, 3 S. acremonium, 3 S. candida, 3 S. flava, 1 S. brumptii and 1 S. fusca) were tested using Sensititre Yeast One and broth microdilution methods to determine the minimum inhibitory concentrations (MICs) to amphotericin B, fluconazole, itraconazole, posaconazole, voriconazole and 5-fluorocytosine, and minimun effective concentration (MECs) to anidulafungin, caspofungin and micafungin. Results: Our data confirm the high in vitro resistance of Scopulariopsis to antifungal agents. Anidulafungin, caspofungin, micafungin (MICs ≥ 8 mg/L), 5-fluorocytosine (MICs ≥ 64 mg/L), and fluconazole (MICs ≥ 128 mg/L) were inactive in vitro in all species. MICs of amphotericin B (range 2 to ≥ 8 mg/L) and itraconazole (0.5 to ≥ 16 mg/L) were high. The best antifungal activity was observed for posaconazole and voriconazole (0.5 to ≥ 8 mg/L). With Sensititre Yeast One method MICs obtained slightly lower. Scopulariopsis candida, S. flava and S. fusca were the most resistant species, while S. acremonium and S. brevicaulis showed the lowest MICs. Conclusions: MICs of all tested antifungal agents for Scopulariopsis were very high. Infections caused by Scopulariopsis species may not respond to antifungal treatment. Voriconazole is the drug of choice for treatment. We consider it appropriate to add amphotericin B in serious infections.
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Papers by Manuel Rodriguez-Iglesias