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Rossel CAJ, Hendrickx APA, van Alphen LB, van der Horst RPJ, Janssen AHJW, Kooyman CC, Heddema ER. Tracing the origin of NDM-1-producing and extensively drug-resistant Pseudomonas aeruginosa ST357 in the Netherlands. BMC Infect Dis 2024; 24:817. [PMID: 39134941 PMCID: PMC11321177 DOI: 10.1186/s12879-024-09722-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Accepted: 08/06/2024] [Indexed: 08/15/2024] Open
Abstract
BACKGROUND In the hospital environment, carbapenemase-producing Pseudomonas aeruginosa (CPPA) may lead to fatal patient infections. However, the transmission routes of CPPA often remain unknown. Therefore, this case study aimed to trace the origin of CPPA ST357, which caused a hospital-acquired pneumonia in a repatriated critically ill patient suffering from Guillain-Barré Syndrome in 2023. METHODS Antimicrobial susceptibility of the CPPA isolate for 30 single and combination therapies was determined by disk-diffusion, Etest or broth microdilution. Whole-genome sequencing was performed for three case CPPA isolates (one patient and two sinks) and four distinct CPPA ST357 patient isolates received in the Dutch CPPA surveillance program. Furthermore, 193 international P. aeruginosa ST357 assemblies were collected via three genome repositories and analyzed using whole-genome multi-locus sequence typing in combination with antimicrobial resistance gene (ARG) characterization. RESULTS A Dutch patient who carried NDM-1-producing CPPA was transferred from Kenya to the Netherlands, with subsequent dissemination of CPPA isolates to the local sinks within a month after admission. The CPPA case isolates presented an extensively drug-resistant phenotype, with susceptibility only for colistin and cefiderocol-fosfomycin. Phylogenetic analysis showed considerable variation in allelic distances (mean = 150, max = 527 alleles) among the ST357 isolates from Asia (n = 92), Europe (n = 58), Africa (n = 21), America (n = 16), Oceania (n = 2) and unregistered regions (n = 4). However, the case isolates (n = 3) and additional Dutch patient surveillance program isolates (n = 2) were located in a sub-clade of isolates from Kenya (n = 17; varying 15-49 alleles), the United States (n = 7; 21-115 alleles) and other countries (n = 6; 14-121 alleles). This was consistent with previous hospitalization in Kenya of 2/3 Dutch patients. Additionally, over half of the isolates (20/35) in this sub-clade presented an identical resistome with 9/17 Kenyan, 5/5 Dutch, 4/7 United States and 2/6 other countries, which were characterized by the blaNDM-1, aph(3')-VI, ARR-3 and cmlA1 ARGs. CONCLUSION This study presents an extensively-drug resistant subclone of NDM-producing P. aeruginosa ST357 with a unique resistome which was introduced to the Netherlands via repatriation of critically ill patients from Kenya. Therefore, the monitoring of repatriated patients for CPPA in conjunction with vigilance for the risk of environmental contamination is advisable to detect and prevent further dissemination.
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Affiliation(s)
- Connor A J Rossel
- Department of Medical Microbiology and Infection Prevention, Zuyderland Medical Center, Sittard-Geleen, The Netherlands.
| | - Antoni P A Hendrickx
- Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
| | - Lieke B van Alphen
- Department of Medical Microbiology, Infectious Diseases and Infection Prevention, Maastricht University Medical Center, Maastricht, The Netherlands
| | | | - Augustinus H J W Janssen
- Department of Intensive Care Medicine, Zuyderland Medical Center, Sittard-Geleen, The Netherlands
| | - Cornelia C Kooyman
- Department of Medical Microbiology and Infection Prevention, Zuyderland Medical Center, Sittard-Geleen, The Netherlands
| | - Edou R Heddema
- Department of Medical Microbiology and Infection Prevention, Zuyderland Medical Center, Sittard-Geleen, The Netherlands
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Lady J, Nurcahyanti ADR, Tjoa E. Synergistic Effect and Time-Kill Evaluation of Eugenol Combined with Cefotaxime Against Staphylococcus aureus. Curr Microbiol 2023; 80:244. [PMID: 37310571 DOI: 10.1007/s00284-023-03364-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 06/03/2023] [Indexed: 06/14/2023]
Abstract
Eugenol, a clove-derived aromatic compound has shown antibacterial activity against many species, including Staphylococcus aureus. Epidemiology studies from the past two decades reported an increased number of healthcare-associated and skin tissue infections due to S. aureus antimicrobial resistance (AMR) including several cases of resistance to β-lactam antibiotics, such as cefotaxime. We aimed to investigate whether eugenol can cause lethality of S. aureus including the strain resistant to methicillin and the wild strain isolated from a hospital patient. Moreover, we asked whether eugenol could enhance the therapeutic effect of cefotaxime, one of the most prescribed 3rd generation cephalosporin β-lactam antibiotics, of which S. aureus resistance to this antibiotic has emerged. The minimum inhibitory concentration (MIC) of each substance was determined using the standard broth microdilution test following the combination experiment performed using checkerboard dilution. The type of interactions, including synergistic and additivity, was determined using isobologram analysis, and the dose reduction index (DRI) was calculated. The time-kill kinetic assay was performed to evaluate the dynamic bactericidal activity of eugenol alone and in combination with cefotaxime. We showed that eugenol alone is bactericidal against S. aureus ATCC 33591 and the clinical isolate. Eugenol combined with cefotaxime resulted synergistic effect against S. aureus ATCC 33591, ATCC 29213, and ATCC 25923. Eugenol may be capable to improve the therapeutic effect of cefotaxime against methicillin-resistant S. aureus (MRSA).
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Affiliation(s)
- Jullietta Lady
- Department of Pharmacy, School of Medicine and Health Sciences, Atma Jaya Catholic University of Indonesia, Pluit Raya 2, Jakarta, 14440, Indonesia
| | - Agustina D R Nurcahyanti
- Department of Pharmacy, School of Medicine and Health Sciences, Atma Jaya Catholic University of Indonesia, Pluit Raya 2, Jakarta, 14440, Indonesia.
| | - Enty Tjoa
- Department of Microbiology, School of Medicine and Health Sciences, Atma Jaya Catholic University of Indonesia, Pluit Raya 2, Jakarta, 14440, Indonesia
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Ceftazidime-Avibactam plus Aztreonam for the Treatment of Infections by VIM-Type-Producing Gram-Negative Bacteria. Antimicrob Agents Chemother 2022; 66:e0075122. [PMID: 36102635 PMCID: PMC9578418 DOI: 10.1128/aac.00751-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
This is a retrospective single-center study of 24 patients who received ceftazidime-avibactam plus aztreonam (CZA/ATM) for the treatment of VIM-type-producing Gram-negative bacillus (GNB) infections. The bacteria isolated were Enterobacterales in 22 patients and Pseudomonas aeruginosa in 2. Sixteen out of 19 isolates showed synergistic activity. Two patients presented clinical failure at day 14, and the 30-day mortality was 17% (4/24). CZA/ATM could be considered an alternative therapy for VIM-type-producing GNB infections.
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Antimicrobial Synergy Testing: Comparing the Tobramycin and Ceftazidime Gradient Diffusion Methodology Used in Assessing Synergy in Cystic Fibrosis-Derived Multidrug-Resistant Pseudomonas aeruginosa. Antibiotics (Basel) 2021; 10:antibiotics10080967. [PMID: 34439017 PMCID: PMC8388873 DOI: 10.3390/antibiotics10080967] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/26/2021] [Accepted: 08/04/2021] [Indexed: 11/17/2022] Open
Abstract
The need for synergy testing is driven by the necessity to extend the antimicrobial spectrum, reducing drug dosage/toxicity and the development of resistance. Despite the abundance of synergy testing methods, there is the absence of a gold standard and a lack of synergy correlation among methods. The most popular method (checkerboard) is labor-intensive and is not practical for clinical use. Most clinical laboratories use several gradient synergy methods which are quicker/easier to use. This study sought to evaluate three gradient synergy methods (direct overlay, cross, MIC:MIC ratio) with the checkerboard, and compare two interpretative criteria (the fractional inhibitory concentration index (FICI) and susceptibility breakpoint index (SBPI)) regarding these methods. We tested 70 multidrug-resistant Pseudomonas aeruginosa, using a tobramycin and ceftazidime combination. The agreement between the checkerboard and gradient methods was 60 to 77% for FICI, while agreements for SBPI that ranged between 67 and 82.86% were statistically significant (p ≤ 0.001). High kappa agreements were observed using SBPI (Ƙ > 0.356) compared to FICI (Ƙ < 0.291) criteria, and the MIC:MIC method demonstrated the highest, albeit moderate, intraclass correlation coefficient (ICC = 0.542) estimate. Isolate resistance profiles suggest method-dependent synergism for isolates, with ceftazidime susceptibility after increased exposure. The results show that when interpretative criteria are considered, gradient diffusion (especially MIC:MIC) is a valuable and practical method that can inform the treatment of cystic fibrosis patients who are chronically infected with P. aeruginosa.
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Bläckberg A, Falk L, Oldberg K, Olaison L, Rasmussen M. Infective Endocarditis Due to Corynebacterium Species: Clinical Features and Antibiotic Resistance. Open Forum Infect Dis 2021; 8:ofab055. [PMID: 33738317 PMCID: PMC7953647 DOI: 10.1093/ofid/ofab055] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 01/28/2021] [Indexed: 11/14/2022] Open
Abstract
Background Corynebacterium species are often dismissed as contaminants in blood cultures, but they can also cause infective endocarditis (IE), which is a severe condition. Antibiotic resistance of corynebacteria is increasing making treatment challenging. Reports on IE caused by Corynebacterium species are scarce and more knowledge is needed. Methods Cases of IE caused by Corynebacterium species were identified through the Swedish Registry of Infective Endocarditis. Isolates were collected for species redetermination by matrix-assisted laser desorption ionization-time of flight and for antibiotic susceptibility testing using Etests. Results Thirty episodes of IE due to Corynebacterium species were identified between 2008 and 2017. The median age of patients was 71 years (interquartile range, 60–76) and 77% were male. Corynebacterium striatum (n = 11) was the most common IE causing pathogen followed by Corynebacterium jeikeium (n = 5). Surgery was performed in 50% and in-hospital mortality rate was 13%. Patients with IE caused by Corynebacterium species were significantly more likely to have prosthetic valve endocarditis (70%), compared with patients with IE due to Staphylococcus aureus or non-beta-hemolytic streptococci (14% and 26%, respectively) (P < .0001). Vancomycin was active towards all Corynebacterium isolates, whereas resistance towards penicillin G was common. Conclusions Corynebacterium species cause IE, where prosthetic valves are mainly affected and surgery is often performed. Corynebacterium striatum is an important causative agent of IE within the genus. Antibiotic resistance of corynebacteria is relatively common but resistance towards vancomycin could not be detected in vitro.
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Affiliation(s)
- Anna Bläckberg
- Division of Infection Medicine, Department of Clinical Sciences Lund, Lund University, Sweden.,Division of Infectious Diseases, Skåne University Hospital, Lund, Sweden
| | - Linn Falk
- Division of Infection Medicine, Department of Clinical Sciences Lund, Lund University, Sweden
| | - Karl Oldberg
- Division of Infection Medicine, Department of Clinical Sciences Lund, Lund University, Sweden.,Department of Clinical Microbiology, Region Skåne, Lund, Sweden
| | - Lars Olaison
- Department of Infectious Diseases, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden.,Head of Swedish Registry of Infective Endocarditis, Swedish Society of Infectious Diseases, Sweden
| | - Magnus Rasmussen
- Division of Infection Medicine, Department of Clinical Sciences Lund, Lund University, Sweden.,Division of Infectious Diseases, Skåne University Hospital, Lund, Sweden
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Jahan S, Davis H, Ashcraft DS, Pankey GA. Evaluation of the in vitro interaction of fosfomycin and meropenem against metallo-β-lactamase-producing Pseudomonas aeruginosa using Etest and time-kill assay. J Investig Med 2020; 69:371-376. [PMID: 33122248 DOI: 10.1136/jim-2020-001573] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2020] [Indexed: 11/04/2022]
Abstract
Pseudomonas aeruginosa is a nosocomial pathogen containing various resistance mechanisms. Among them, metallo-β-lactamase (MBL)-producing Pseudomonas are difficult to treat. Fosfomycin is an older antibiotic that has recently seen increased usage due to its activity against a broad spectrum of multidrug-resistant organisms. Our aim was to evaluate the combination of fosfomycin and meropenem against 20 MBL-producing P. aeruginosa (100% meropenem-resistant and 20% fosfomycin-resistant) using both an Etest minimal inhibitory concentration (MIC): MIC method and time-kill assay. MICs for fosfomycin and meropenem were determined by Etest and by broth microdilution method for the latter. The combination demonstrated synergy by Etest in 3/20 (15%) isolates and 5/20 (25%) isolates by time-kill assay. Results from the Etest method and time-kill assay were in agreement for 14/20 (70%) of isolates. No antagonism was found. Comparing both methods, Etest MIC: MIC method may be useful to rapidly evaluate other antimicrobial combinations.
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Affiliation(s)
- Sanjida Jahan
- Infectious Disease Translational Research, Ochsner Clinic Foundation, New Orleans, Louisiana, USA
| | - Heather Davis
- Infectious Disease Translational Research, Ochsner Clinic Foundation, New Orleans, Louisiana, USA
| | - Deborah S Ashcraft
- Infectious Disease Translational Research, Ochsner Clinic Foundation, New Orleans, Louisiana, USA
| | - George A Pankey
- Infectious Disease Translational Research, Ochsner Clinic Foundation, New Orleans, Louisiana, USA .,Infectious Disease Translational Research, Ochsner Clinic Foundation, New Orleans, Louisiana, USA
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Vivas R, Dolabella SS, Barbosa AAT, Jain S. Prevalence of Klebsiella pneumoniae carbapenemase - and New Delhi metallo-beta-lactamase-positive K. pneumoniae in Sergipe, Brazil, and combination therapy as a potential treatment option. Rev Soc Bras Med Trop 2020; 53:e20200064. [PMID: 32401864 PMCID: PMC7269519 DOI: 10.1590/0037-8682-0064-2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 04/02/2020] [Indexed: 12/01/2022] Open
Abstract
INTRODUCTION Carbapenem-resistant Klebsiella pneumoniae infection lacks treatment options and is associated with prolonged hospital stays and high mortality rates. The production of carbapenemases is one of the most important factors responsible for this multi-resistance phenomenon. METHODS In the present study, we analyzed the presence of genes encoding carbapenemases in K. pneumoniae isolates circulating in one of the public hospitals in the city of Aracaju, Sergipe, Brazil. We also determined the best combination of drugs that display in vitro antimicrobial synergy. First, 147 carbapenem-resistant K. pneumoniae isolates were validated for the presence of blaKPC, bla GES, bla NDM, bla SPM, bla IMP, bla VIM, and bla OXA-48 genes using multiplex polymerase chain reaction. Thereafter, using two isolates (97 and 102), the role of double and triple combinational drug therapy as a treatment option was analyzed. RESULTS Seventy-four (50.3%) isolates were positive for bla NDM, eight (5.4%) for bla KPC, and one (1.2%) for both bla NDM and bla KPC. In the synergy tests, double combinations were better than triple combinations. Polymyxin B and amikacin for isolate 97 and polymyxin B coupled with meropenem for isolate 102 showed the best response. CONCLUSIONS Clinicians in normal practice use multiple drugs to treat infections caused by multi-resistant microorganism; however, in most cases, the benefit of the combinations is unknown. In vitro synergistic tests, such as those described herein, are important as they might help select an appropriate multi-drug antibiotic therapy and a correct dosage, ultimately reducing toxicities and the development of antibiotic resistance.
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Affiliation(s)
- Roberto Vivas
- Universidade Federal de Sergipe, Programa de Pós-Graduação em
Biologia Parasitária, São Cristóvão, SE, Brasil
| | - Silvio Santana Dolabella
- Universidade Federal de Sergipe, Programa de Pós-Graduação em
Biologia Parasitária, São Cristóvão, SE, Brasil
| | - Ana Andréa Teixeira Barbosa
- Universidade Federal de Sergipe, Programa de Pós-Graduação em
Biologia Parasitária, São Cristóvão, SE, Brasil
| | - Sona Jain
- Universidade Federal de Sergipe, Programa de Pós-Graduação em
Biologia Parasitária, São Cristóvão, SE, Brasil
- Universidade Tiradentes, Programa de Pós-Graduação em Biotecnologia
Industrial, Aracaju, SE, Brasil
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Gaudereto JJ, Neto LVP, Leite GC, Espinoza EPS, Martins RCR, Villas Boa Prado G, Rossi F, Guimarães T, Levin AS, Costa SF. Comparison of methods for the detection of in vitro synergy in multidrug-resistant gram-negative bacteria. BMC Microbiol 2020; 20:97. [PMID: 32299353 PMCID: PMC7161189 DOI: 10.1186/s12866-020-01756-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 03/20/2020] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND The use of combined antibiotic therapy has become an option for infections caused by multidrug-resistant (MDR) bacteria. The time-kill (TK) assay is considered the gold standard method for the evaluation of in vitro synergy, but it is a time-consuming and expensive method. The purpose of this study was to evaluate two methods for testing in vitro antimicrobial combinations: the disk diffusion method through disk approximation (DA) and the agar gradient diffusion method via the MIC:MIC ratio. The TK assay was included as the gold standard. MDR Gram-negative clinical isolates (n = 62; 28 Pseudomonas aeruginosa, 20 Acinetobacter baumannii, and 14 Serratia marcescens) were submitted to TK, DA, and MIC:MIC ratio synergy methods. RESULTS Overall, the agreement between the DA and TK assays ranged from 20 to 93%. The isolates of A. baumannii showed variable results of synergism according to TK, and the calculated agreement was statistically significant in this species against fosfomycin with meropenem including colistin-resistant isolates. The MIC:MIC ratiometric agreed from 35 to 71% with TK assays. The kappa test showed good agreement for the combination of colistin with amikacin (K = 0.58; P = 0.04) among the colistin-resistant A. baumannii isolates. CONCLUSIONS The DA and MIC:MIC ratiometric methods are easier to perform and might be a more viable tool for clinical microbiology laboratories.
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Affiliation(s)
- Juliana Januario Gaudereto
- Laboratório de Investigação Médica 49 - LIM-49, Instituto de Medicina Tropical, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Avenida Doutor Enéas de Carvalho Aguiar, 470, São Paulo, SP, 05403-000, Brazil
| | - Lauro Vieira Perdigão Neto
- Laboratório de Investigação Médica 49 - LIM-49, Instituto de Medicina Tropical, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Avenida Doutor Enéas de Carvalho Aguiar, 470, São Paulo, SP, 05403-000, Brazil
| | - Gleice Cristina Leite
- Laboratório de Investigação Médica 49 - LIM-49, Instituto de Medicina Tropical, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Avenida Doutor Enéas de Carvalho Aguiar, 470, São Paulo, SP, 05403-000, Brazil
| | - Evelyn Patricia Sanchez Espinoza
- Laboratório de Investigação Médica 49 - LIM-49, Instituto de Medicina Tropical, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Avenida Doutor Enéas de Carvalho Aguiar, 470, São Paulo, SP, 05403-000, Brazil
| | - Roberta Cristina Ruedas Martins
- Laboratório de Investigação Médica 49 - LIM-49, Instituto de Medicina Tropical, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Avenida Doutor Enéas de Carvalho Aguiar, 470, São Paulo, SP, 05403-000, Brazil
| | - Gladys Villas Boa Prado
- Laboratório de Investigação Médica 49 - LIM-49, Instituto de Medicina Tropical, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Avenida Doutor Enéas de Carvalho Aguiar, 470, São Paulo, SP, 05403-000, Brazil
| | - Flavia Rossi
- Divisão de Laboratório Central - Serviço de Microbiologia Clínica, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Thais Guimarães
- Laboratório de Investigação Médica 49 - LIM-49, Instituto de Medicina Tropical, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Avenida Doutor Enéas de Carvalho Aguiar, 470, São Paulo, SP, 05403-000, Brazil
| | - Anna Sara Levin
- Laboratório de Investigação Médica 49 - LIM-49, Instituto de Medicina Tropical, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Avenida Doutor Enéas de Carvalho Aguiar, 470, São Paulo, SP, 05403-000, Brazil
| | - Silvia Figueiredo Costa
- Laboratório de Investigação Médica 49 - LIM-49, Instituto de Medicina Tropical, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Avenida Doutor Enéas de Carvalho Aguiar, 470, São Paulo, SP, 05403-000, Brazil.
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In vitro synergy with fosfomycin plus doxycyclin against linezolid and vancomycin-resistant Enterococcus faecium. J Glob Antimicrob Resist 2020; 22:78-83. [PMID: 32007618 DOI: 10.1016/j.jgar.2020.01.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 12/05/2019] [Accepted: 01/20/2020] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE Linezolid and vancomycin-resistant Enterococcus faecium (LRVREF) is globally emerging as a urinary nosocomial pathogen. A decrease in the amount of successful treatment options has created a necessity for the development of novel antimicrobial therapies. Combination therapy may provide an effective alternative for treatment. Fosfomycin and doxycyclin are currently used individually for the treatment of urinary tract infections. Fosfomycin has recently seen increased use because of its persistent activity against a large spectrum of multidrug-resistant organisms. The purpose of this study was to investigate the interaction of fosfomycin plus doxycyclin against LRVREF isolates. METHODS MICs for fosfomycin and doxycyclin were determined for 24 unique clinical LRVREF isolates (4%, fosfomycin-susceptible; 92%, doxycyclin-susceptible). In vitro synergy testing with the combination of fosfomycin and doxycyclin was performed using an Etest method and time-kill assay. RESULTS The combination of fosfomycin and doxycyclin demonstrated synergy with the Etest method in 11/24 (46%) isolates and in 10/24 (42%) isolates by the time-kill assay. Results from the Etest method and time-kill assay were in agreement for 7/24 (29.2%) of isolates. No antagonism was found. CONCLUSIONS The combination of fosfomycin and doxycyclin should be evaluated further with additional LRVREF isolates. In vivo studies should also be performed before use in clinical situations.
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Gil Romero Y, Gómez-Garcés JL. In vitro activity of ceftaroline in combination with other antimicrobials active against Staphylococcus spp. Enferm Infecc Microbiol Clin 2020; 38:25-27. [PMID: 31072712 DOI: 10.1016/j.eimc.2019.03.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 03/03/2019] [Accepted: 03/12/2019] [Indexed: 11/25/2022]
Abstract
INTRODUCTION We evaluated the in vitro activity of the combination of ceftaroline with daptomycin, linezolid and vancomycin against methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococcus (CNS). MATERIAL AND METHODS We analysed 70 staphylococcal strains (31 S. aureus and 39 CNS) with the Etest using the MIC:MIC ratio method and calculation of fractional inhibitory concentration indexes. RESULTS The combination of ceftaroline with daptomycin showed an additive effect (53.2%) and synergy (6.6%) against methicillin-susceptible S. aureus, and an additive effect (81.2%) against methicillin-resistant S. aureus (MRSA). This combination also showed an additive effect against 33% of linezolid-susceptible CNS and was not synergistic against linezolid-resistant CNS. The combination of ceftaroline with vancomycin was synergistic (87%) and ceftaroline with linezolid was additive (37%) against MRSA. CONCLUSIONS The combinations of ceftaroline with daptomycin, vancomycin or linezolid showed additive and/or synergistic effects against methicillin-resistant Staphylococcus.
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Affiliation(s)
- Yolanda Gil Romero
- Servicio de Microbiología, Hospital Universitario de Móstoles, Móstoles, Madrid, España.
| | - José-Luis Gómez-Garcés
- Instituto de Investigación Biomédica, Hospital Universitario de Móstoles, Móstoles, Madrid, España
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Mashaly G, Shrief R. Candida glabrata complex from patients with healthcare-associated infections in Mansoura University Hospitals, Egypt: distribution, antifungal susceptibility and effect of fluconazole and polymyxin B combination. Germs 2019; 9:125-132. [PMID: 31646142 DOI: 10.18683/germs.2019.1167] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Revised: 06/26/2019] [Accepted: 06/29/2019] [Indexed: 01/31/2023]
Abstract
Introduction Candida glabrata complex is composed of three cryptic species, Candida glabrata sensu stricto, C. bracarensis and C. nivariensis. Its reduced susceptibility to fluconazole is responsible for treatment failure of its infections. Combination therapy is recommended to treat these resistant strains. This study assessed the distribution of C. glabrata complex collected from patients in Mansoura University Hospitals and their antifungal susceptibility, with evaluation of fluconazole and polymyxin B combination against them. Methods C. glabrata complex was collected from patients with healthcare-associated infections. The isolates were identified biochemically then the species were detected using multiplex PCR. The susceptibility of isolates to antifungals and polymyxin B was tested by the microdilution assay. The effect of fluconazole and polymyxin B combination was assessed by checkerboard microdilution and time kill assays. Results This study included 45 isolates of Candida glabrata complex. The common isolate was Candida glabrata sensu stricto (38 isolates). There were 4 isolates of C. bracarensis and three isolates of C. nivariensis. All isolates were susceptible to amphotericin B, and 17.8% were susceptible to itraconazole. Regarding fluconazole, 48.9% of isolates were susceptible dose-dependent and 51.1% were resistant. Synergistic effect of the combination was observed in 68.9% of isolates by the checkerboard method and in 66.7% of isolates using the time kill assay. Conclusions Candida glabrata sensu stricto is the main member of the complex. Combination of fluconazole and polymyxin B can be considered a treatment option for fluconazole resistant C. glabrata complex infections. In vivo studies are needed to validate these results.
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Affiliation(s)
- Ghada Mashaly
- MD, Department of Medical Microbiology and Immunology, Faculty of Medicine, Mansoura University, Mansoura, 35516, Egypt
| | - Raghdaa Shrief
- PhD, Department of Medical Microbiology and Immunology, Faculty of Medicine, Mansoura University, Mansoura, 35516, Egypt
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Brennan-Krohn T, Kirby JE. When One Drug Is Not Enough: Context, Methodology, and Future Prospects in Antibacterial Synergy Testing. Clin Lab Med 2019; 39:345-358. [PMID: 31383261 PMCID: PMC6686866 DOI: 10.1016/j.cll.2019.04.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Antibacterial combinations have long been used to accomplish a variety of therapeutic goals, including prevention of resistance and enhanced antimicrobial activity. In vitro synergy testing methods, including the checkerboard array, the time-kill study, diffusion assays, and pharmacokinetic/pharmacodynamic models, are used commonly in the research setting, but are not routinely performed in the clinical microbiology laboratory because of test complexity and uncertainty about their predictive value for patient outcomes. Optimized synergy testing techniques and better data on the relationship between in vitro results and clinical outcomes are needed to guide the rational use of antimicrobial combinations in the multidrug resistance era.
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Affiliation(s)
- Thea Brennan-Krohn
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, 3 Blackfan Circle - CLS0624, Boston, MA 02115, USA; Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - James E Kirby
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue - YA309, Boston, MA 02215, USA.
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13
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Papoutsaki V, Galani I, Papadimitriou E, Karantani I, Karaiskos I, Giamarellou H. Evaluation of in vitro methods for testing tigecycline combinations against carbapenemase-producing Klebsiella pneumoniae isolates. J Glob Antimicrob Resist 2019; 20:98-104. [PMID: 31398495 DOI: 10.1016/j.jgar.2019.07.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 07/26/2019] [Accepted: 07/26/2019] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVES Treatment of infections caused by carbapenemase-producing Klebsiella pneumoniae (CPKP) frequently involves combination therapy with various antimicrobial agents in the hope of achieving synergistic effects. Routine laboratory antimicrobial synergy testing is a service that is currently unavailable owing to the laborious nature of the reference time-kill assay (TKA) as well as the widely used chequerboard method. In this study, we explored whether easier methods, based on the Etest technique, might offer a suitable alternative. METHODS In vitro interactions of tigecycline combination with colistin, gentamicin, fosfomycin or meropenem against 26 CPKP isolates were evaluated employing the TKA, chequerboard method and three Etest methodologies (the MIC/MIC ratio, the cross formation and the agar/Etest method). Rates of consequent synergy and concordance of the studied methods were determined. RESULTS All antimicrobial combinations demonstrated some degree of synergy against the CPKP isolates tested. No antagonism was observed for any of the combinations. All methods showed poor synergy concordance with the TKA, producing non-significant kappa (κ) results. Etest methods (MIC/MIC ratio and agar/Etest) exhibited fair agreement (κ=0.29 and 0.38, respectively) with the chequerboard method. CONCLUSION There is a poor correlation between synergy testing methods of tigecycline combinations, which may be associated with their different endpoints. To elucidate method comparability and reliability, their correlation with clinical outcomes appears important.
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Affiliation(s)
| | - Irene Galani
- Infectious Diseases Laboratory, 4th Department of Internal Medicine, National and Kapodistrian University of Athens, School of Medicine, Athens, Greece
| | - Eleni Papadimitriou
- Infectious Diseases Laboratory, 4th Department of Internal Medicine, National and Kapodistrian University of Athens, School of Medicine, Athens, Greece
| | - Irene Karantani
- Microbiology Department, Hygeia General Hospital, Athens, Greece
| | - Ilias Karaiskos
- 1st Internal Medicine & Infectious Diseases Clinic, Hygeia General Hospital, 4 Erythrou Stavrou Str. & Kifisias Av., Marousi Athens, 151 23 Greece
| | - Helen Giamarellou
- 1st Internal Medicine & Infectious Diseases Clinic, Hygeia General Hospital, 4 Erythrou Stavrou Str. & Kifisias Av., Marousi Athens, 151 23 Greece.
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14
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Ojdana D, Gutowska A, Sacha P, Majewski P, Wieczorek P, Tryniszewska E. Activity of Ceftazidime-Avibactam Alone and in Combination with Ertapenem, Fosfomycin, and Tigecycline Against Carbapenemase-Producing Klebsiella pneumoniae. Microb Drug Resist 2019; 25:1357-1364. [PMID: 31295055 DOI: 10.1089/mdr.2018.0234] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The aim of this study was to investigate the synergy between ceftazidime-avibactam, ertapenem, fosfomycin, and tigecycline against carbapenemase-producing Klebsiella pneumoniae using the E test MIC:MIC (minimum inhibitory concentration) ratio synergy method. The results were interpreted using fractional inhibitory concentration index (FICI) to describe the effects of antimicrobial combinations in vitro. To assess the clinical significance of each antibiotic combination, the susceptible breakpoint index (SBPI) was calculated for each combination, and within each strain. The FICI method revealed that the most synergistic combinations against carbapenemase-producing K. pneumoniae were ceftazidime-avibactam with ertapenem and ceftazidime-avibactam with fosfomycin. This effect was demonstrated in 47% (9/19) of all tested clinical K. pneumoniae isolates. Considering the effects of all drug combinations in K. pneumoniae harboring blaKPC, blaNDM, and blaOXA-48 genes, we observed that the combination of ceftazidime-avibactam with fosfomycin was the most synergistic in New Delhi metallo-β-lactamase (NDM)-producing K. pneumoniae, and the combination of ceftazidime-avibactam with ertapenem was the most synergistic in K. pneumoniae carbapenemase (KPC)-producing K. pneumoniae. In addition, all tested combinations were synergistic against oxacillinase (OXA)-48-producing K. pneumoniae, except the combination of ceftazidime-avibactam with tigecycline. The SBPI index showed that ceftazidime-avibactam in combination with fosfomycin reduced the MIC to less than the susceptibility breakpoint among all tested carbapenemase-producing K. pneumoniae. Moreover, the combinations of ceftazidime-avibactam with ertapenem, and ceftazidime-avibactam with tigecycline were able to reduce the MIC to less than the susceptibility breakpoint in all KPC- and OXA-48-producing K. pneumoniae.
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Affiliation(s)
- Dominika Ojdana
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | - Anna Gutowska
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | - Paweł Sacha
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | - Piotr Majewski
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | - Piotr Wieczorek
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | - Elżbieta Tryniszewska
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
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15
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Abstract
Pneumonia, including community-acquired bacterial pneumonia, hospital-acquired bacterial pneumonia, and ventilator-acquired bacterial pneumonia, carries unacceptably high morbidity and mortality. Despite advances in antimicrobial therapy, emergence of multidrug resistance and high rates of treatment failure have made optimization of antibiotic efficacy a priority. This review focuses on pharmacokinetic and pharmacodynamic approaches to antibacterial optimization within the lung environment and in the setting of critical illness. Strategies for including these approaches in drug development programs as well as clinical practice are described and reviewed.
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Affiliation(s)
- Ana Motos
- Center for Anti-Infective Research and Development, Hartford Hospital, 80 Seymour Street, Hartford, CT 06102, USA; Division of Animal Experimentation, Department of Pulmonary and Critical Care, Hospital Clinic, 170 Villarroel Street, Barcelona 08036, Spain
| | - James M Kidd
- Center for Anti-Infective Research and Development, Hartford Hospital, 80 Seymour Street, Hartford, CT 06102, USA
| | - David P Nicolau
- Center for Anti-Infective Research and Development, Hartford Hospital, 80 Seymour Street, Hartford, CT 06102, USA; Division of Infectious Diseases, Hartford Hospital, 80 Seymour Street, Hartford, CT 06102, USA.
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16
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Avery LM, Sutherland CA, Nicolau DP. In vitro investigation of synergy among fosfomycin and parenteral antimicrobials against carbapenemase-producing Enterobacteriaceae. Diagn Microbiol Infect Dis 2019; 95:216-220. [PMID: 31213392 DOI: 10.1016/j.diagmicrobio.2019.05.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 05/06/2019] [Accepted: 05/16/2019] [Indexed: 11/30/2022]
Abstract
Intravenous fosfomycin is undergoing clinical development in the United States for treatment of complicated urinary tract infections (cUTIs) and may be prescribed as a component of dual antibiotic regimens against carbapenemase-producing Enterobacteriaceae (CPE). Fosfomycin, aztreonam, cefepime, ceftazidime, ceftazidime/avibactam, ceftolozane/tazobactam, meropenem, piperacillin/tazobactam, and tobramycin minimum inhibitory concentrations (MICs) were determined by gradient diffusion strip (GDS) against CPE isolates (N = 49). The GDS cross method was used to assess antibiotic interactions between fosfomycin and the aforementioned parenteral antibiotics. The resultant fractional inhibitory concentration index was used to classify interactions. Fosfomycin-containing combinations were evaluated only if nonsusceptible to the second agent. The fosfomycin MIC50 was ≥1024 mg/L by GDS. Synergy or additivity was detected in 80 (22%) fosfomycin-containing combinations. Antagonism was not observed. Ceftolozane/tazobactam most frequently displayed synergy [8 (16.3%) isolates]. When CPE are isolated, clinical laboratories should consider performing GDS synergy tests to identify favorable antibiotic interactions.
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Affiliation(s)
- Lindsay M Avery
- Center for Anti-Infective Research and Development, Hartford Hospital, Hartford, CT, USA
| | - Christina A Sutherland
- Center for Anti-Infective Research and Development, Hartford Hospital, Hartford, CT, USA
| | - David P Nicolau
- Center for Anti-Infective Research and Development, Hartford Hospital, Hartford, CT, USA; Division of Infectious Diseases, Hartford Hospital, Hartford, CT, USA.
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17
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Avery LM, Sutherland CA, Nicolau DP. Prevalence of in vitro synergistic antibiotic interaction between fosfomycin and nonsusceptible antimicrobials in carbapenem-resistant Pseudomonas aeruginosa. J Med Microbiol 2019; 68:893-897. [PMID: 31050629 DOI: 10.1099/jmm.0.000984] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
PURPOSE We assessed the synergistic potential of fosfomycin and parenteral antibiotics among carbapenem-resistant Pseudomonas aeruginosa (CRP). METHODOLOGY Minimum inhibitory concentrations (MICs) were determined by broth microdilution for all antibiotics except fosfomycin, for which the gradient diffusion strip (GDS) method was used. The GDS cross method was performed to assess interactions between fosfomycin and: aztreonam, cefepime, ceftazidime, ceftazidime/avibactam, ceftolozane/tazobactam, meropenem, piperacillin/tazobactam and tobramycin. Only organisms that were nonsusceptible to the second drug were assessed. RESULTS Among 153 clinical isolates, the fosfomycin MIC50/90 was 48/≥1024 mg l-1 . Synergy was detected in 131/604 (21.7 %) fosfomycin-antibiotic combinations among 76 (49.7 %) isolates. Ceftazidime (42/81, 51.9%) and ceftolozane/tazobactam (7/14, 50.0%) displayed synergy most frequently. Meropenem susceptibility was restored in 21 (13.7 %) isolates. Antagonism was not observed. CONCLUSION Fosfomycin synergy was commonly observed in vitro among CRP. These data may guide the selection of combination antibiotic therapy. The susceptibility to other antibiotics was restored in combination with fosfomycin, warranting further in vivo evaluation.
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Affiliation(s)
- Lindsay M Avery
- 1 Center for Anti-Infective Research and Development, Hartford Hospital, Hartford, CT, USA
| | - Christina A Sutherland
- 1 Center for Anti-Infective Research and Development, Hartford Hospital, Hartford, CT, USA
| | - David P Nicolau
- 2 Division of Infectious Diseases, Hartford Hospital, Hartford, CT, USA.,1 Center for Anti-Infective Research and Development, Hartford Hospital, Hartford, CT, USA
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18
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Colistin monotherapy versus colistin/rifampicin combination therapy in pneumonia caused by colistin-resistant Acinetobacter baumannii: A randomised controlled trial. J Glob Antimicrob Resist 2018; 17:66-71. [PMID: 30476654 DOI: 10.1016/j.jgar.2018.11.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 11/16/2018] [Accepted: 11/17/2018] [Indexed: 11/20/2022] Open
Abstract
OBJECTIVES The aim of this study was to confirm the synergistic effect of colistin/rifampicin combination therapy compared with colistin monotherapy in pneumonia caused by colistin-resistant Acinetobacter baumannii (CoRAB). The utility of the Etest was also assessed. METHODS Nine subjects with pneumonia caused by CoRAB were enrolled from 20 July 2016 to 21 June 2018. Subjects were randomised to colistin/rifampicin combination therapy or colistin monotherapy. After exclusion of one patient who dropped out, the microbiological response (MR) and clinical response (CR) on Day 14 and mortality on Day 30 were assessed. Etest was conducted using CoRAB isolated at study enrolment. RESULTS The MR rate in the colistin/rifampicin combination group (100.0%) was better than that in the colistin group (40.0%), however the difference was not statistically significant (P=0.196). The CR rate was not significantly different between the two groups. The MR (100.0%) and CR (100.0%) rates in subjects with 'partial synergy' as shown by Etest were higher than those (25.0% and 50.0%, respectively) in subjects with 'indifferent' results (i.e. no synergistic effect), however the difference was not statistically significant (P=0.143 and 0.429, respectively). Mortality occurred in two subjects with 'indifferent' results by Etest. CONCLUSIONS Colistin/rifampicin combination therapy may have potential to achieve MR in pneumonia caused by CoRAB; however, achieving CR with this treatment is doubtful. 'Partial synergy' of colistin and rifampicin, as shown by Etest, may be a good prognostic factor [ClinicalTrial.gov ID: NCT03622918].
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19
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Bläckberg A, Nilson B, Özenci V, Olaison L, Rasmussen M. Infective endocarditis due to Streptococcus dysgalactiae: clinical presentation and microbiological features. Eur J Clin Microbiol Infect Dis 2018; 37:2261-2272. [PMID: 30196469 DOI: 10.1007/s10096-018-3367-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 08/27/2018] [Indexed: 01/17/2023]
Abstract
Knowledge of infective endocarditis (IE) caused by Streptococcus dysgalactiae (SD) is limited. This study aimed to identify the clinical and microbiological features of SD-caused IE and to investigate any possible synergy between penicillin and gentamicin on SD isolates. Cases of IE 2008-2016 due to SD reported to the Swedish Registry of Infective Endocarditis (SRIE) were identified. Isolates were emm typed and synergy between antibiotics was determined in time-kill experiments. Medical records were reviewed and SD-cases were compared to cases of IE due to other pathogens reported to the SRIE. Fifty cases of SD-caused IE were confirmed. emm types stC74a, stG62647, and stG643 were most commonly encountered. The patients had a median age of 74 years (range 38-93) and were significantly older compared to patients with Staphylococcus aureus-caused IE, (65 years (p = 0.003)). The median time to diagnosis from symptom onset was 1 day for patients with SD-caused IE which was less compared to patients with IE due to the other pathogens (2-15 days). Embolization was seen in 46% and the in-hospital mortality was 8%. Etest-based methods did not indicate any synergy between penicillin and gentamicin whereas synergy was noted for four out of nine isolates applying time-kill assays. This is the largest study of SD-caused IE, a condition with an acute onset predominantly affecting elderly people. Synergy between penicillin and gentamicin against some SD isolates was distinguished but the potential benefit of this must be weighed against the risk of aminoglycoside side effects.
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Affiliation(s)
- Anna Bläckberg
- Department of Clinical Sciences, Division of Infection Medicine, Lund University, BMC B14 Baravägen 27, 223 63, Lund, Sweden.
| | - Bo Nilson
- Clinical Microbiology, Labmedicin, Region Skåne, Lund, Sweden.,Department of Laboratory Medicine Lund, Section of Medical Microbiology, Lund University, Lund, Sweden
| | - Volkan Özenci
- Department of Clinical Microbiology, Karolinska University Hospital, Huddinge, Stockholm, Sweden.,Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Lars Olaison
- Department of Infectious Diseases, Sahlgrenska University Hospital, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden.,Swedish Society of Infectious Diseases, Swedish Registry of Infective Endocarditis, Gothenburg, Sweden
| | - Magnus Rasmussen
- Department of Clinical Sciences, Division of Infection Medicine, Lund University, BMC B14 Baravägen 27, 223 63, Lund, Sweden
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20
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Laishram S, Pragasam AK, Bakthavatchalam YD, Veeraraghavan B. An update on technical, interpretative and clinical relevance of antimicrobial synergy testing methodologies. Indian J Med Microbiol 2018; 35:445-468. [PMID: 29405135 DOI: 10.4103/ijmm.ijmm_17_189] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Testing for antimicrobial interactions has gained popularity in the last decade due to the increasing prevalence of drug-resistant organisms and limited options for the treatment of these infections. In vitro combination testing provides information, on which two or more antimicrobials can be combined for a good clinical outcome. Amongst the various in vitro methods of drug interactions, time-kill assay (TKA), checkerboard (CB) assay and E-test-based methods are most commonly used. Comparative performance of these methods reveals the TKA as the most promising method to detect synergistic combinations followed by CB assay and E-test. Various combinations of antimicrobials have been tested to demonstrate synergistic activity. Promising results were obtained for the combinations of meropenem plus colistin and rifampicin plus colistin against Acinetobacter baumannii, colistin plus carbapenem and carbapenem plus fluoroquinolones against Pseudomonas aeruginosa and colistin/polymyxin B plus rifampicin/meropenem against Klebsiella pneumoniae. Antagonism was detected in only few instances. The presence of synergy or antagonism with a combination seems to correlate with minimum inhibitory concentration of the agent and molecular mechanism involved in the resistance. Further studies need to be conducted to assess the utility of in vitro testing to predict clinical outcome and direct therapy for drug-resistant organisms.
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Affiliation(s)
- Shakti Laishram
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu,, India
| | - Agila Kumari Pragasam
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu,, India
| | | | - Balaji Veeraraghavan
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu,, India
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21
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Assessing the in vitro activity of ceftazidime/avibactam and aztreonam among carbapenemase-producing Enterobacteriaceae: Defining the zone of hope. Int J Antimicrob Agents 2018; 52:688-691. [PMID: 30044946 DOI: 10.1016/j.ijantimicag.2018.07.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 07/06/2018] [Accepted: 07/14/2018] [Indexed: 11/23/2022]
Abstract
Ceftazidime/avibactam plus aztreonam (CZA+ATM) is an emerging option to combat carbapenemase-producing Enterobacteriaceae (CPE) expressing resistance via multiple β-lactamases within Ambler classes A, B, C, and D. The benefit of this combination is apparent when the pathogen-specific resistance genotype is characterized. However, rapid molecular diagnostic systems may be unavailable to allow this precision medicine-based approach. Using synergy tests with antibiotic gradient diffusion strips (GDSs), we aimed to prove that the defined phenotypic profile of CPE is reliably predicted by the genotype to confirm the utility of this method as a phenotypic profiling tool for use in the clinical setting. Synergy assessments for CPE (n=10) that co-produce serine- and metallo-β-lactamases were performed by crossing CZA and ATM antibiotic GDSs (Liofilchem® and Etest®). The minimum inhibitory concentration (MIC):MIC ratio method was also conducted for five CPE. All CPE were resistant to CZA and ATM when tested alone. Using classical fractional inhibitory concentration definitions, synergy (9/10) and additivity (1/10) was detected by at least one method for all isolates. As predicted by cross-coverage of genotypically defined serine- and metallo-β-lactamases, for all isolates CZA+ATM produced a phenotypic profile distinguished by sizeable zones of inhibited growth which we term the 'zone of hope'. In conclusion, simple procedures utilizing antibiotic GDSs were concordant with the known genotypic profile of the CPE selected for study. This approach appears to be a valuable tool for guiding therapy in the absence of molecular diagnostic systems. Furthermore, this study confirms potent in vitro activity of CZA+ATM against CPE expressing multiple β-lactamases.
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22
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Avery LM, Nicolau DP. Feasibility of routine synergy testing using antibiotic gradient diffusion strips in the clinical laboratory. J Antimicrob Chemother 2018; 73:2264-2265. [DOI: 10.1093/jac/dky165] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Lindsay M Avery
- Center for Anti-Infective Research and Development, Hartford Hospital, Hartford, CT, USA
| | - David P Nicolau
- Center for Anti-Infective Research and Development, Hartford Hospital, Hartford, CT, USA
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23
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Hooper RW, Ashcraft DS, Pankey GA. In vitrosynergy with fluconazole plus doxycycline or tigecycline against clinicalCandida glabrataisolates. Med Mycol 2018; 57:122-126. [DOI: 10.1093/mmy/myy008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 02/06/2018] [Indexed: 11/13/2022] Open
Affiliation(s)
- Randol W Hooper
- University of Queensland-Ochsner Clinical School, New Orleans, Louisiana, USA
| | - Deborah S Ashcraft
- Infectious Disease Translational Research Laboratory, Ochsner Clinic Foundation, New Orleans, Louisiana, USA
| | - George A Pankey
- Infectious Disease Translational Research Laboratory, Ochsner Clinic Foundation, New Orleans, Louisiana, USA
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24
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Wenzler E, Deraedt MF, Harrington AT, Danizger LH. Synergistic activity of ceftazidime-avibactam and aztreonam against serine and metallo-β-lactamase-producing gram-negative pathogens. Diagn Microbiol Infect Dis 2017; 88:352-354. [DOI: 10.1016/j.diagmicrobio.2017.05.009] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 05/08/2017] [Accepted: 05/12/2017] [Indexed: 11/24/2022]
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25
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Piedra-Carrasco N, Miguel L, Fàbrega A, Viñado B, Campany D, Mir A, Fox ML, Almirante B, Larrosa N, Ruiz-Camps I, González-López JJ. Effectiveness of a Double-Carbapenem Regimen in a KPC-Producing Klebsiella pneumoniae Infection in an Immunocompromised Patient. Microb Drug Resist 2017; 24:199-202. [PMID: 28708458 DOI: 10.1089/mdr.2017.0129] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The progressive increase of infections produced by extensively drug-resistant carbapenemase-producing Klebsiella pneumoniae (XDR-CPKP) represents an important threat to public health. Unfortunately, optimal therapeutic options are scarce. Retrospective studies have recommended combined therapy with more than one antibiotic and, more recently, a double-carbapenem regimen has been reported to be an effective alternative therapy. Here, we describe an episode of sepsis in an immunocompromised patient after allogeneic hematopoietic stem cell transplantation, caused by an XDR-CPKP. Several in vitro synergy tests revealed a synergistic effect combining ertapenem and meropenem, which were used as combination therapy achieving clinical and microbiological success.
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Affiliation(s)
- Nuria Piedra-Carrasco
- 1 Department of Clinical Microbiology, Hospital Vall d'Hebron, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona , Barcelona, Spain
| | - Lucia Miguel
- 2 Department of Infectious Diseases, Hospital Vall d'Hebron, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona , Barcelona, Spain
| | - Anna Fàbrega
- 1 Department of Clinical Microbiology, Hospital Vall d'Hebron, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona , Barcelona, Spain
| | - Belén Viñado
- 1 Department of Clinical Microbiology, Hospital Vall d'Hebron, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona , Barcelona, Spain
| | - David Campany
- 3 Department of Pharmacy, Hospital Vall d'Hebron, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona , Barcelona, Spain
| | - Alba Mir
- 1 Department of Clinical Microbiology, Hospital Vall d'Hebron, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona , Barcelona, Spain
| | - María Laura Fox
- 4 Hematology Department, Hospital Vall d'Hebron, Vall d'Hebron Institute of Oncology (VHIO) , Barcelona, Spain
| | - Benito Almirante
- 2 Department of Infectious Diseases, Hospital Vall d'Hebron, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona , Barcelona, Spain
| | - Nieves Larrosa
- 1 Department of Clinical Microbiology, Hospital Vall d'Hebron, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona , Barcelona, Spain
| | - Isabel Ruiz-Camps
- 2 Department of Infectious Diseases, Hospital Vall d'Hebron, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona , Barcelona, Spain
| | - Juan José González-López
- 1 Department of Clinical Microbiology, Hospital Vall d'Hebron, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona , Barcelona, Spain
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D'Arezzo S, Mazzarelli A, Venditti C, Nisii C, Petrosillo N, De Giuli C, Vulcano A, Paglia MG, Bordi E, Di Caro A, Taglietti F. Ceftaroline Plus Ampicillin Against Gram-Positive Organisms: Results from E-Test Synergy Assays. Microb Drug Resist 2017; 23:507-515. [PMID: 27526275 DOI: 10.1089/mdr.2016.0030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In an era of increasing drug resistance and limited numbers of antimicrobials in the drug production pipeline, healthcare-associated infections represent a growing public health threat. When therapeutic options are limited, clinicians often resort to using antimicrobial combinations that produce a synergistic effect on the target pathogen. Novel antibiotics are therefore welcome in the daily practice of medicine. For example, ceftaroline is a broad-spectrum cephalosporin active against a variety of bacteria, including methicillin-resistant Staphylococcus aureus, but with limited activity against enterococci, particularly Enterococcus faecium. In this study, we tested the efficacy of ceftaroline against clinical isolates of gram-positive bacteria (S. aureus, Enterococcus faecalis, and E. faecium) by the broth microdilution and E-test assays, and then evaluated the synergistic effect of ceftaroline and ampicillin using the E-test method. The time-kill assay was used to confirm the data on selected strains. This drug combination has been recently shown to be effective against E. faecalis and could offer the advantage of cost-effectiveness (compared to other synergistic associations) as well as good tolerability. The E-test was chosen because of its relative simplicity of use that makes it suitable for routine clinical laboratories as a quick tool to guide clinicians when confronted with difficult-to-treat infections that may require an empirical approach. Our results indicate the presence of a synergistic effect of ceftaroline and ampicillin on most of the strains used, especially E. faecium and E. faecalis. The fact that two of those Enterococcus strains were vancomycin resistant suggests that the possible use of this combination for combating the spread of vancomycin-resistant enterococci should be explored.
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Affiliation(s)
- Silvia D'Arezzo
- "Lazzaro Spallanzani" National Institute for Infectious Diseases IRCCS , Rome, Italy
| | - Antonio Mazzarelli
- "Lazzaro Spallanzani" National Institute for Infectious Diseases IRCCS , Rome, Italy
| | - Carolina Venditti
- "Lazzaro Spallanzani" National Institute for Infectious Diseases IRCCS , Rome, Italy
| | - Carla Nisii
- "Lazzaro Spallanzani" National Institute for Infectious Diseases IRCCS , Rome, Italy
| | - Nicola Petrosillo
- "Lazzaro Spallanzani" National Institute for Infectious Diseases IRCCS , Rome, Italy
| | - Chiara De Giuli
- "Lazzaro Spallanzani" National Institute for Infectious Diseases IRCCS , Rome, Italy
| | - Antonella Vulcano
- "Lazzaro Spallanzani" National Institute for Infectious Diseases IRCCS , Rome, Italy
| | - Maria Grazia Paglia
- "Lazzaro Spallanzani" National Institute for Infectious Diseases IRCCS , Rome, Italy
| | - Eugenio Bordi
- "Lazzaro Spallanzani" National Institute for Infectious Diseases IRCCS , Rome, Italy
| | - Antonino Di Caro
- "Lazzaro Spallanzani" National Institute for Infectious Diseases IRCCS , Rome, Italy
| | - Fabrizio Taglietti
- "Lazzaro Spallanzani" National Institute for Infectious Diseases IRCCS , Rome, Italy
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Hong DJ, Kim JO, Lee H, Yoon EJ, Jeong SH, Yong D, Lee K. In vitro antimicrobial synergy of colistin with rifampicin and carbapenems against colistin-resistant Acinetobacter baumannii clinical isolates. Diagn Microbiol Infect Dis 2016; 86:184-9. [PMID: 27475960 DOI: 10.1016/j.diagmicrobio.2016.07.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 07/13/2016] [Accepted: 07/15/2016] [Indexed: 01/12/2023]
Abstract
Increased use of colistin in a clinical setting had resulted in the emergence of colistin-resistant (CoR) Acinetobacter baumannii. Combination therapy has been studied as a new approach to treat infections caused by A. baumannii. Here, we investigated the in vitro antimicrobial synergistic activities of several antimicrobial agent combinations against CoR A. baumannii. A total of 41 non-duplicate clinical isolates of CoR A. baumannii from a tertiary care hospital in Korea were prospectively collected from April 2012 to December 2014. As a control group, 41 carbapenem-resistant but colistin-susceptible (CoS) A. baumannii strains were also evaluated. Minimum inhibitory concentrations (MICs) of antimicrobial agents were determined by Etest in triplicate, and in vitro synergy tests were performed by the Etest MIC:MIC ratio method. Synergistic activity was determined as the sum of each antimicrobial agent's fractional inhibitory concentration evaluated (ΣFIC): synergy, ≤0.5; indifference, >0.5-4; and antagonism, >4. Synergistic activities were more frequently observed in the CoR group than the CoS group for combinations of colistin-rifampicin (80.5% vs. 14.6%, P< 0.0001), colistin-meropenem (85.4% vs. 4.9%, P< 0.0001), and colistin-imipenem (46.3% vs. 2.4%, P< 0.0001). Combination with rifampicin or meropenem lowered colistin MICs against CoR A. baumannii clinical isolates to the susceptible range (≤ 2 μg/mL) more frequently (61.0%, 25/41, both) than combination with imipenem (29.3%, 12/41). Clinical trials are needed to prove the in vivo efficacy of those antimicrobial combinations that exhibited significant in vitro antimicrobial synergistic effects against CoR A. baumannii.
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Affiliation(s)
- Duck Jin Hong
- Department of Laboratory Medicine, Eone Reference Laboratory, Incheon, Seoul, Republic of Korea; Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jung Ok Kim
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Hyukmin Lee
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Eun-Jeong Yoon
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Seok Hoon Jeong
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Republic of Korea.
| | - Dongeun Yong
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Kyungwon Lee
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Republic of Korea
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28
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Sunnerhagen T, Nilson B, Olaison L, Rasmussen M. Clinical and microbiological features of infective endocarditis caused by aerococci. Infection 2015; 44:167-73. [PMID: 26119199 DOI: 10.1007/s15010-015-0812-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 06/13/2015] [Indexed: 10/23/2022]
Abstract
PURPOSE To define the clinical presentation of aerococcal infective endocarditis (IE) and the prevalence of synergy between penicillin and gentamicin on aerococcal isolates. METHODS Cases of aerococcal IE between 2002 and 2014 were identified in the Swedish Registry of Infective Endocarditis (SRIE). MALDI-TOF MS was used to confirm species determination. The medical records were analysed and compared to cases reported to the SRIE caused by other pathogens. RESULTS Sixteen cases of aerococcal IE, fourteen with Aerococcus urinae and two with Aerococcus sanguinicola, were confirmed. Etest-based methods and time-kill experiments suggested synergy between penicillin and gentamicin towards seven of fifteen isolates. The patients with aerococcal IE were significantly older than those with streptococci or Staphylococcus aureus IE. Most of the patients had underlying urinary tract diseases or symptoms suggesting a urinary tract focus of the infection. Seven patients with aerococcal IE presented with severe sepsis but ICU treatment was needed only in one patient and there was no fatality. Valve exchange surgery was needed in four patients and embolization was seen in three patients. CONCLUSIONS This report is the largest on aerococcal IE and suggests that the prognosis is relatively favourable despite the fact that the patients are old and have significant comorbidities.
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Affiliation(s)
- Torgny Sunnerhagen
- Division of Infection Medicine, Department of Clinical Sciences, Lund University, Tornavägen 10, BMC B14, 221 84, Lund, Sweden
| | - Bo Nilson
- Clinical Microbiology, Labmedicin, Region Skåne, Lund, Sweden.,Department of Laboratory Medicine Lund, Section of Medical Microbiology, Lund University, Lund, Sweden
| | - Lars Olaison
- Department of Infectious Diseases, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden.,Swedish Registry of Infective Endocarditis, Swedish Society of Infectious Diseases, Gothenburg, Sweden
| | - Magnus Rasmussen
- Division of Infection Medicine, Department of Clinical Sciences, Lund University, Tornavägen 10, BMC B14, 221 84, Lund, Sweden.
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29
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Sunnerhagen T, Nilson B, Rasmussen M. Antibiotic synergy against viridans streptococci isolated in infective endocarditis. Int J Antimicrob Agents 2015; 45:550-1. [PMID: 25697413 DOI: 10.1016/j.ijantimicag.2015.01.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 01/20/2015] [Accepted: 01/21/2015] [Indexed: 10/24/2022]
Affiliation(s)
- Torgny Sunnerhagen
- Division of Infection Medicine, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Bo Nilson
- Clinical Microbiology, Region Skåne, Lund, Sweden; Division of Medical Microbiology, Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Magnus Rasmussen
- Division of Infection Medicine, Department of Clinical Sciences, Lund University, Lund, Sweden.
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30
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A case of suspected infective endocarditis with Lactococcus garvieae: lack of in vitro synergy between ampicillin and gentamicin. JMM Case Rep 2015. [DOI: 10.1099/jmmcr.0.000018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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31
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Maraki S, Papadakis IS. Evaluation of antimicrobial combinations against colistin-resistant carbapenemase (KPC)-producing Klebsiella pneumoniae. J Chemother 2014; 27:348-52. [PMID: 25248023 DOI: 10.1179/1973947814y.0000000218] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Affiliation(s)
- S Maraki
- Department of Bacteriology, Parasitology, Zoonoses and Geographical Medicine, University Hospital of Heraklion , Crete, Greece
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32
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van Belkum A, Halimi D, Bonetti EJ, Renzi G, Cherkaoui A, Sauvonnet V, Martelin R, Durand G, Chatellier S, Zambardi G, Engelhardt A, Karlsson Å, Schrenzel J. Meropenem/colistin synergy testing for multidrug-resistant Acinetobacter baumannii strains by a two-dimensional gradient technique applicable in routine microbiology. J Antimicrob Chemother 2014; 70:167-72. [PMID: 25239465 DOI: 10.1093/jac/dku342] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
OBJECTIVES Precise assessment of potential therapeutic synergy, antagonism or indifference between antimicrobial agents currently depends on time-consuming and hard-to-standardize in vitro chequerboard titration methods. We here present a method based on a novel two-dimensional antibiotic gradient technique named Xact™. METHODS We used a test comprising a combination of perpendicular gradients of meropenem and colistin in a single quadrant. We compared test outcomes with those obtained with classical chequerboard microbroth dilution testing in a study involving 27 unique strains of multidrug-resistant Acinetobacter baumannii from diverse origins. RESULTS We were able to demonstrate 92% concordance between the new technology and classical chequerboard titration using the A. baumannii collection. Two strains could not be analysed by Xact™ due to their out-of-range MIC of meropenem (>128 mg/L). CONCLUSIONS The new test was shown to be diagnostically useful, easy to implement and less labour intensive than the classical method.
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Affiliation(s)
- Alex van Belkum
- Microbiology R&D, Microbiology Unit, bioMérieux SA, La Balme Les Grottes, France
| | - Diane Halimi
- Microbiology R&D, Microbiology Unit, bioMérieux SA, La Balme Les Grottes, France
| | - Eve-Julie Bonetti
- Genomic Research Laboratory, Service of Infectious Diseases, Geneva University Hospital (HUG), Geneva, Switzerland
| | - Gesuele Renzi
- Bacteriology Laboratory, Service of Infectious Diseases, Geneva University Hospital (HUG), Geneva, Switzerland
| | - Abdessalam Cherkaoui
- Bacteriology Laboratory, Service of Infectious Diseases, Geneva University Hospital (HUG), Geneva, Switzerland
| | - Véronique Sauvonnet
- Microbiology R&D, Microbiology Unit, bioMérieux SA, La Balme Les Grottes, France
| | - Roland Martelin
- Microbiology R&D, Microbiology Unit, bioMérieux SA, La Balme Les Grottes, France
| | - Géraldine Durand
- Microbiology R&D, Microbiology Unit, bioMérieux SA, La Balme Les Grottes, France
| | - Sonia Chatellier
- Microbiology R&D, Microbiology Unit, bioMérieux SA, La Balme Les Grottes, France
| | - Gilles Zambardi
- Microbiology R&D, Microbiology Unit, bioMérieux SA, La Balme Les Grottes, France
| | - Anette Engelhardt
- AB BIODISK Research Laboratories, Solna, Sweden Franchise Identification/Antimicrobial Susceptibility Testing, Microbiology Unit, bioMérieux Inc., St Louis, MO, USA
| | - Åsa Karlsson
- Microbiology R&D, Microbiology Unit, bioMérieux SA, La Balme Les Grottes, France AB BIODISK Research Laboratories, Solna, Sweden
| | - Jacques Schrenzel
- Genomic Research Laboratory, Service of Infectious Diseases, Geneva University Hospital (HUG), Geneva, Switzerland Bacteriology Laboratory, Service of Infectious Diseases, Geneva University Hospital (HUG), Geneva, Switzerland
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33
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Time-kill assay and Etest evaluation for synergy with polymyxin B and fluconazole against Candida glabrata. Antimicrob Agents Chemother 2014; 58:5795-800. [PMID: 25049251 DOI: 10.1128/aac.03035-14] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fluconazole-resistant Candida glabrata is an emerging pathogen that causes fungemia. Polymyxin B, a last-resort antibiotic used to treat multidrug-resistant Gram-negative bacterial infections, has been found to possess in vitro fungicidal activity and showed synergy with fluconazole against a single strain of C. glabrata. Since both agents may be used simultaneously in intensive care unit (ICU) patients, this study was performed to test for possible synergy of this combination against 35 C. glabrata blood isolates, using 2 methods: a time-kill assay and an experimental MIC-MIC Etest method. Thirty-five genetically unique C. glabrata bloodstream isolates were collected from 2009 to 2011, identified using an API 20C system, and genotyped by repetitive sequence-based PCR (rep-PCR). MICs were determined by Etest and broth microdilution methods. Synergy testing was performed using a modified bacterial Etest synergy method and time-kill assay, with final results read at 24 h. The Etest method showed synergy against 19/35 (54%) isolates; the time-kill assay showed synergy against 21/35 (60%) isolates. Isolates not showing drug synergy had an indifferent status. Concordance between methods was 60%. In vitro synergy of polymyxin B and fluconazole against the majority of C. glabrata isolates was demonstrated by both methods. The bacterial Etest synergy method adapted well when used with C. glabrata. Etest was easier to perform than time-kill assay and may be found to be an acceptable alternative to time-kill assay with antifungals.
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