scholarly journals Investigation of in vitro activity of colistin and tygecyclin against Stenotrophomonas maltophilia isolates

2021 ◽  
Vol 38 (4) ◽  
pp. 529-532
Author(s):  
Yeliz TANRIVERDİ ÇAYCI ◽  
İlknur BIYIK ◽  
Gonca YILMAZ ◽  
Kemal BİLGİN ◽  
Asuman BİRİNCİ
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Inhibitory Concentration ◽  
Treatment Options ◽  
Opportunistic Pathogen ◽  
Diffusion Method ◽  
Colistin Resistance ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
The Usa

Stenotrophomonas maltophilia has emerged as an important opportunistic pathogen, causing infections whose management is often problematic due to its inherent resistance to many antibiotics. In this study, we aimed to investigate the antimicrobial susceptibility of colistin and tygecyclin as an alternative treatment options for S. maltophilia infections. A total of 122 S. maltophilia isolates were tested. Minimum inhibitory concentration (MIC) values of colistin and tygecycline were determined by broth microdilution method. Susceptibility of TMP/SMX and levofloxacin (LVX) were determined by disc diffusion method and MIC value of ceftazidime (CAZ) was determined by using E-test. Out of 122 S. maltophilia isolates, 5 (4%) of them were resistant to TMP-SXM. MIC range was 0.125- >512 μg/ml and MIC50 64 μg/ml, MIC90 512 μg/ml for colistin. MIC range for tygecyclin was detected as 0.5- >8, MIC50 2 μg/ml and MIC90 8 μg/ml. Tygecyclin resistance was detected as 66.4% according to the EUCAST guideline and 13.1% according to the USA-FDA breakpoints. And colistin resistance was determined as 86.9% according to both guidelines.

scholarly journals In Vitro Evaluation of the activity of Ceftazidime-avibactam and Aztreonam-Avibactam against 76 Stenotrophomonas maltophilia isolates from a teaching hospital in Chongqing

2020 ◽  
Author(s):  
Qiuxia Lin ◽  
Hua Zou ◽  
Xian Chen ◽  
Menglu Wu ◽  
Deyu Ma ◽  
...  
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Combined Therapy ◽  
Treatment Options ◽  
Clinical Isolates ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Medical University ◽  
Selection Of

Abstract Background: Treatment options for Stenotrophomonas maltophilia (S. maltophilia) infections were limited. We assessed the efficacy of ceftazidime-avibactam (CAZ-AVI) and aztreonam-avibactam (ATM-AVI) against a selection of 76 S. maltophilia out of the 1179 strains isolated from the First Affiliated Hospital of Chongqing Medical University during 2011-2018. Methods: We investigated the antimicrobial resistance profiles of the 1179 S. maltophilia clinical isolates from the first affiliated hospital of Chongqing Medical University during 2011-2018, a collection of 76 isolates of which were available for further study of microbiological characterization. Minimum inhibitory concentrations (MICs) of ceftazidime (CAZ), ceftazidime-avibactam (CAZ-AVI), aztreonam (ATM) and aztreonam-avibactam (ATM-AVI) were determined via the broth microdilution method. We deemed that CAZ-AVI or ATM-AVI was more effective in vitro than CAZ or ATM alone when CAZ-AVI or ATM-AVI led to a category change from “Resistant” with CAZ or ATM alone to “Susceptible” or “Intermediate” with CAZ-AVI or ATM-AVI, or if the MIC of CAZ-AVI or ATM-AVI was at least 2-fold lower than the MIC of CAZ or ATM alone. Results: For the 76 clinical isolates included in the study, MICs of CAZ, ATM, CAZ-AVI and ATM-AVI ranged from 0.03-64, 1-1024, 0.016-64, and 0.06-64 μg/mL, respectively. In combined therapy, AVI was effective at restoring the susceptibility of 48.48% (16/33) and 89.71% (61/68) of S. maltophilia to CAZ and ATM, respectively. Furthermore, CAZ-AVI showed better results in terms of the proportion of susceptible isolates (77.63% vs.56.58%, P<0.001), MIC50 (2μg/mL vs. 8μg/mL, P<0.05), and MIC distribution (P<0.001) when compared to CAZ. According to our definition, CAZ-AVI was more effective in vitro than CAZ alone for 84.21% of the isolates. Similarly, ATM-AVI also showed better results in terms of the proportion of susceptible isolates (90.79%vs. 10.53%, P<0.001), MIC50 (2μg/mL vs. 64μg/mL, P<0.001), and MIC distribution (P<0.001) when compared to ATM. According to our definition, ATM-AVI was also more effective in vitro than ATM alone for 97.37% of the isolates. Conclusions: AVI potentiated the activity of both CAZ and ATM against S. maltophilia clinical isolates in vitro. We demonstrated that CAZ-AVI and ATM-AVI are both useful therapeutic options to treat infections caused by S. maltophilia.

Antimicrobial activity of POL7306 tested against clinical isolates of Gram-negative bacteria collected worldwide

2020 ◽  
Vol 75 (6) ◽  
pp. 1518-1524 ◽  
Author(s):  
Helio S Sader ◽  
Paul R Rhomberg ◽  
Leonard R Duncan ◽  
Hans H Locher ◽  
Glenn E Dale ◽  
...  
Keyword(s):  
Protein Targeting ◽  
Treatment Options ◽  
Asia Pacific ◽  
Surveillance Program ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
The Usa

Abstract Background POL7306 belongs to a new class of peptidomimetic outer-membrane-protein-targeting antibiotics with a novel mechanism of action. POL7306 is in development for the treatment of infections caused by antimicrobial-resistant Gram-negative bacteria and has demonstrated low cytotoxicity and nephrotoxicity. Methods A total of 891 isolates were collected by the SENTRY Antimicrobial Surveillance Program from 134 medical centres in Europe (n = 424; 41 centres in 18 nations), the USA (n = 411 isolates from 67 centres), the Asia-Pacific region (n = 24; 15 centres in 6 nations) and Latin America (n = 32; 11 centres in 9 nations) and included 558 Enterobacterales, 310 non-fermenters and 23 fastidious organisms. Susceptibility testing was performed using the reference broth microdilution method and the medium was supplemented with 0.002% polysorbate-80 for testing POL7306. Resistant subsets were characterized by WGS. Results POL7306 demonstrated potent in vitro activity against Enterobacterales [including carbapenem-resistant (MIC50/90, 0.06/0.25 mg/L), ESBL-producing (MIC50/90, 0.06/0.12 mg/L), KPC-producing (MIC50/90, 0.12/0.25 mg/L), MBL-producing (MIC50/90, 0.06/0.25 mg/L), colistin-non-susceptible, mcr-negative (MIC50/90, 0.5/2 mg/L) and mcr-positive (MIC50/90, 0.12/0.25 mg/L) Enterobacterales], Pseudomonas aeruginosa (MIC50/90, 0.25/0.25 mg/L), Acinetobacter baumannii (MIC50/90, 0.06/0.12 mg/L) and Stenotrophomonas maltophilia (MIC50/90, 0.06/0.25 mg/L). Conclusions POL7306 demonstrated potent activity against a large collection of Gram-negative organisms collected worldwide that included colistin-resistant, XDR and ESBL- and carbapenemase-producing isolates for which there are currently limited treatment options.

scholarly journals Avibactam potentiated the activity of both ceftazidime and aztreonam against S. maltophilia clinical isolates in vitro

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Qiuxia Lin ◽  
Hua Zou ◽  
Xian Chen ◽  
Menglu Wu ◽  
Deyu Ma ◽  
...  
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Combined Therapy ◽  
Treatment Options ◽  
Clinical Isolates ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Medical University ◽  
Selection Of

Abstract Background Treatment options for Stenotrophomonas maltophilia (S. maltophilia) infections were limited. We assessed the efficacy of ceftazidime (CAZ), ceftazidime-avibactam (CAZ-AVI), aztreonam (ATM), and aztreonam-avibactam (ATM-AVI) against a selection of 76 S. maltophilia out of the 1179 strains isolated from the First Affiliated Hospital of Chongqing Medical University during 2011–2018. Methods We investigated the antimicrobial resistance profiles of the 1179 S. maltophilia clinical isolates from the first affiliated hospital of Chongqing Medical University during 2011–2018, a collection of 76 isolates were selected for further study of microbiological characterization. Minimum inhibitory concentrations (MICs) of CAZ, CAZ-AVI, ATM and ATM-AVI were determined via the broth microdilution method. We deemed that CAZ-AVI or ATM-AVI was more active in vitro than CAZ or ATM alone when CAZ-AVI or ATM-AVI led to a category change from “Resistant” or “Intermediate” with CAZ or ATM alone to “Susceptible” with CAZ-AVI or ATM-AVI, or if the MIC of CAZ-AVI or ATM-AVI was at least 4-fold lower than the MIC of CAZ or ATM alone. Results For the 76 clinical isolates included in the study, MICs of CAZ, ATM, CAZ-AVI and ATM-AVI ranged from 0.03–64, 1–1024, 0.016–64, and 0.06–64 μg/mL, respectively. In combined therapy, AVI was active at restoring the activity of 48.48% (16/33) and 89.71% (61/68) of S. maltophilia to CAZ and ATM, respectively. Furthermore, CAZ-AVI showed better results in terms of the proportion of susceptible isolates (77.63% vs. 56.58%, P < 0.001), and MIC50 (2 μg/mL vs. 8 μg/mL, P < 0.05) when compared to CAZ. According to our definition, CAZ-AVI was more active in vitro than CAZ alone for 81.58% (62/76) of the isolates. Similarly, ATM-AVI also showed better results in terms of the proportion of susceptible isolates (90.79% vs.10.53%, P < 0.001) and MIC50 (2 μg/mL vs. 64 μg/mL, P < 0.001) when compared to ATM. According to our definition, ATM-AVI was also more active in vitro than ATM alone for 94.74% (72/76) of the isolates. Conclusions AVI potentiated the activity of both CAZ and ATM against S. maltophilia clinical isolates in vitro. We demonstrated that CAZ-AVI and ATM-AVI are both useful therapeutic options to treat infections caused by S. maltophilia.

scholarly journals In Vitro Evaluation of The Activity of Ceftazidime-Avibactam and Aztreonam-Avibactam Against 76 Stenotrophomonas Maltophilia Isolates From A Teaching Hospital in Chongqing

2020 ◽  
Author(s):  
Qiuxia Lin ◽  
Hua Zou ◽  
Xian Chen ◽  
Menglu Wu ◽  
Deyu Ma ◽  
...  
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Combined Therapy ◽  
Treatment Options ◽  
Clinical Isolates ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Medical University ◽  
Selection Of

Abstract Background: Treatment options for Stenotrophomonas maltophilia (S. maltophilia) infections were limited. We assessed the efficacy of ceftazidime-avibactam (CAZ-AVI) and aztreonam-avibactam (ATM-AVI) against a selection of 76 S. maltophilia out of the 1179 strains isolated from the First Affiliated Hospital of Chongqing Medical University during 2011-2018.Methods: We investigated the antimicrobial resistance profiles of the 1179 S. maltophilia clinical isolates from the first affiliated hospital of Chongqing Medical University during 2011-2018, a collection of 76 isolates of which were available for further study of microbiological characterization. Minimum inhibitory concentrations (MICs) of ceftazidime (CAZ), ceftazidime-avibactam (CAZ-AVI), aztreonam (ATM) and aztreonam-avibactam (ATM-AVI) were determined via the broth microdilution method. We deemed that CAZ-AVI or ATM-AVI was more effective in vitro than CAZ or ATM alone when CAZ-AVI or ATM-AVI led to a category change from “Resistant” with CAZ or ATM alone to “Susceptible” or “Intermediate” with CAZ-AVI or ATM-AVI, or if the MIC of CAZ-AVI or ATM-AVI was at least 2-fold lower than the MIC of CAZ or ATM alone.Results: For the 76 clinical isolates included in the study, MICs of CAZ, ATM, CAZ-AVI and ATM-AVI ranged from 0.03-64, 1-1024, 0.016-64, and 0.06-64 μg/mL, respectively. In combined therapy, AVI was effective at restoring the susceptibility of 48.48% (16/33) and 89.71% (61/68) of S. maltophilia to CAZ and ATM, respectively. Furthermore, CAZ-AVI showed better results in terms of the proportion of susceptible isolates (77.63% vs.56.58%, P<0.001), MIC50 (2μg/mL vs. 8μg/mL, P<0.05), and MIC distribution (P<0.001) when compared to CAZ. According to our definition, CAZ-AVI was more effective in vitro than CAZ alone for 84.21% of the isolates. Similarly, ATM-AVI also showed better results in terms of the proportion of susceptible isolates (90.79%vs. 10.53%, P<0.001), MIC50 (2μg/mL vs. 64μg/mL, P<0.001), and MIC distribution (P<0.001) when compared to ATM. According to our definition, ATM-AVI was also more effective in vitro than ATM alone for 97.37% of the isolates.Conclusions: AVI potentiated the activity of both CAZ and ATM against S. maltophilia clinical isolates in vitro. We demonstrated that CAZ-AVI and ATM-AVI are both useful therapeutic options to treat infections caused by S. maltophilia.

scholarly journals In Vitro Interaction of Caspofungin Acetate with Voriconazole against Clinical Isolates of Aspergillus spp

2002 ◽  
Vol 46 (9) ◽  
pp. 3039-3041 ◽  
Author(s):  
Sofia Perea ◽  
Gloria Gonzalez ◽  
Annette W. Fothergill ◽  
William R. Kirkpatrick ◽  
Michael G. Rinaldi ◽  
...  
Keyword(s):  
Inhibitory Concentration ◽  
Fractional Inhibitory Concentration ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
In Vitro Interaction ◽  
Vitro Data ◽  
In Vitro Data

ABSTRACT The interaction between caspofungin acetate and voriconazole was studied in vitro by using 48 clinical Aspergillus spp. isolates obtained from patients with invasive aspergillosis. MICs were determined by the NCCLS broth microdilution method. Synergy, defined as a fractional inhibitory concentration (FIC) index of <1, was detected in 87.5% of the interactions; an additive effect, defined as an FIC index of 1.0, was observed in 4.2% of the interactions; and a subadditive effect, defined as an FIC index of 1.0 to 2.0, was found in 8.3% of the interactions. No antagonism was observed. Animal models are required to validate the in vivo significance of these in vitro data presented for the combination of caspofungin and voriconazole.

Evaluation of the in vitro interaction of fosfomycin and meropenem against metallo-β-lactamase–producing Pseudomonas aeruginosa using Etest and time-kill assay

2020 ◽  
pp. jim-2020-001573
Author(s):  
Sanjida Jahan ◽  
Heather Davis ◽  
Deborah S Ashcraft ◽  
George A Pankey
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Inhibitory Concentration ◽  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Time Kill ◽  
In Vitro Interaction ◽  
Antimicrobial Combinations

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.

scholarly journals Ceftaroline-Heteroresistant Staphylococcus aureus

2014 ◽  
Vol 58 (6) ◽  
pp. 3133-3136 ◽  
Author(s):  
Stephanie N. Saravolatz ◽  
Hayley Martin ◽  
Joan Pawlak ◽  
Leonard B. Johnson ◽  
Louis D. Saravolatz
Keyword(s):  
Staphylococcus Aureus ◽  
Population Analysis ◽  
Large Population ◽  
Brain Heart Infusion ◽  
Content Type ◽  
Microdilution Method ◽  
Select Group ◽  
Broth Microdilution Method ◽  
The Usa

ABSTRACTHeteroresistance refers to the presence, within a large population of antimicrobial-susceptible microorganisms, of subpopulations with lesser susceptibilities. Ceftaroline is a novel cephalosporin with activity against methicillin-resistantStaphylococcus aureus(MRSA). The aim of this study was to detect the prevalence of ceftaroline heteroresistancein vitroin a select group ofS. aureusstrains. There were 57 isolates selected for evaluation, 20 MRSA, 20 vancomycin-intermediateS. aureus(VISA), 7 daptomycin-nonsusceptibleS. aureus(DNSSA), 6 linezolid-nonsusceptibleS. aureus(LNSSA), and 4 heteroresistant VISA (hVISA) isolates. MICs and minimal bactericidal concentrations were determined using the broth microdilution method according to CLSI guidelines. All of the isolates were analyzed by pulsed-field gel electrophoresis. The staphylococcal cassette chromosomemecelement (SCCmec) types were determined by a multiplex PCR. Population analysis profiles (PAPs) were performed to determine heteroresistance for all of the isolates using plates made by adding various amounts of ceftaroline to brain heart infusion agar. The frequencies of resistant subpopulations were 1 in 104to 105organisms. We determined that 12 of the 57 (21%) isolates tested were ceftaroline-heteroresistantS. aureus(CHSA). CHSA occurred among strains with reduced susceptibilities to vancomycin, daptomycin, and linezolid but occurred in none of the USA-300 isolates tested. Evaluation of the heteroresistant strains demonstrated that the phenotype was unstable. Further studies are needed to determine whether CHSA has a role in clinical failures and to determine the implications of our study findings.

scholarly journals Caspofungin in Combination with Amphotericin B against Candida parapsilosis

2006 ◽  
Vol 51 (3) ◽  
pp. 941-945 ◽  
Author(s):  
Francesco Barchiesi ◽  
Elisabetta Spreghini ◽  
Serena Tomassetti ◽  
Daniele Giannini ◽  
Giorgio Scalise
Keyword(s):  
Amphotericin B ◽  
Candida Parapsilosis ◽  
Inhibitory Concentration ◽  
Positive Interaction ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Disk Diffusion Assay ◽  
Higher Doses ◽  
Diffusion Assay

ABSTRACT Candida parapsilosis has emerged as an important nosocomial pathogen. In the present study, a checkerboard broth microdilution method was performed to investigate the in vitro activities of caspofungin (CAS) in combination with amphotericin B (AMB) against three clinical isolates of C. parapsilosis. Although there was a significant reduction of the MIC of one or both drugs used in combination, an indifferent interaction (fractional inhibitory concentration index greater than 0.50 and less than or equal to 4.0) was observed in 100% of cases. This finding was confirmed by killing curve studies. By a disk diffusion assay, the halo diameters produced by antifungal agents in combination were often significantly greater than those produced by each drug alone. Antagonism was never observed. In a murine model of systemic candidiasis, CAS at either 0.25 or 1 mg/kg/day combined with AMB at 1 mg/kg/day was significantly more effective than each single drug at reducing the colony counts in kidneys. Higher doses of the echinocandin (i.e., 5 and 10 mg/kg/day) combined with the polyene did not show any advantage over CAS alone. Overall, our study showed a positive interaction of CAS and AMB against C. parapsilosis.

scholarly journals In vitro efficacy of vancomycin combined with fosfomycin against Vancomycin-Resistant Enterococci strains

2019 ◽  
Vol 36 (2) ◽  
Author(s):  
Gulseren Aktas
Keyword(s):  
Inhibitory Concentration ◽  
Distinct Advantage ◽  
Creative Commons ◽  
Microdilution Method ◽  
Vancomycin Resistant Enterococci ◽  
Broth Microdilution Method ◽  
Vancomycin Resistant ◽  
Time Kill ◽  
Open Access Article

Objective: Enterococci have been isolated frequently worldwide and have difficulties in the treatment. Combination antibiotherapies have a distinct advantage over monotherapies in terms of their synergistic effect. In the study, it was aimed to investigate in vitro activity of vancomycin combined with fosfomycin against VRE strains. Methods: A total of 30 VRE strains were included in the study. Bacterial identifications of the strains were undertaken using conventional routine methods. The resistance to agents tested was investigated by using the broth microdilution method. Glucose-6-phosphate (25 mcg/mL) for fosfomycin were used in all experiments. The activity of antibiotics in combination was assessed using a broth microcheckerboard. The fractional inhibitory concentration index (FICI) was interpreted as follows: synergism, FICI ≤0.5. Additionally, two strains in 30 VRE were studied to determine the time-kill curves to verify the synergistic results. For each strain, antibiotics were studied alone and in combination at the minimum inhibitory concentration (1xMIC) values. Results: Susceptibility rate to fosfomycin was found at 26.6 % (8/30). The MIC50, MIC90 and MIC interval values of antimicrobials were 512, 512, and 512 - 1024 mcg/mL for vancomycin, and 128, 160, and 64 - 224 mcg/mL for fosfomycin, respectively. The rate of synergism was found as 100 % by both checkerboard and time-kill methods. Conclusion: The result shows that the combination of vancomycin with fosfomycin could be an alternative in the treatment of infections caused by VRE. doi: https://doi.org/10.12669/pjms.36.2.1347 How to cite this:Aktas G. In vitro efficacy of vancomycin combined with fosfomycin against Vancomycin-Resistant Enterococci strains. Pak J Med Sci. 2020;36(2):281-285. doi: https://doi.org/10.12669/pjms.36.2.1347 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

scholarly journals 1584. Minocycline Activity Against Stenotrophomonas maltophilia Isolated From Patients in US Hospitals

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S578-S578
Author(s):  
Dee Shortridge ◽  
S J Ryan Arends ◽  
Jennifer M Streit ◽  
Mariana Castanheira ◽  
Robert K Flamm
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Bloodstream Infections ◽  
Opportunistic Pathogen ◽  
Resistance Rate ◽  
Hospitalized Patients ◽  
Microdilution Method ◽  
Medical Centers ◽  
Drug Classes ◽  
Broth Microdilution Method ◽  
Infection Types

Abstract Background Stenotrophomonas maltophilia (SM) has emerged as a common hospital-associated opportunistic pathogen found in immunocompromised and immunocompetent patients. SM is intrinsically resistant to many common drug classes, including carbapenems, cephalosporins, and aminoglycosides. Only 4 antibiotics have CLSI breakpoints for SM: minocycline (MIN), ceftazidime (CAZ), levofloxacin (LVX) and trimethoprim-sulfamethoxazole (TMP-SMX). Minocycline is frequently used to treat SM infections. In this study, we analyzed susceptibilities of SM isolates collected as part of the SENTRY Program. We also examined the frequency of SM isolation from pneumonia in hospitalized patients (PIHP) among all Gram-negative (GN) species. Methods From 2014 to 2018, 990 SM isolates were collected from hospitalized patients in 32 US hospitals. Hospitals submitted 1 isolate per patient per infection episode that met local criteria for being the likely causative pathogen and submitted consecutive isolates from pneumonia. Isolates were tested for MIN susceptibility (S) using the CLSI broth microdilution method at JMI Laboratories. Other antimicrobials tested were CAZ, LVX, and TMP-SMX. TMP-SMX was tested 3 of 5 years. All infection types were included in the susceptibility analysis. The prevalence of SM isolates in PIHP during this period was also analyzed. Results There were 9,120 GN pathogens isolated from PIHP. The most commonly isolated species was P. aeruginosa (34.7%), followed by Klebsiella pneumoniae (12.6%), Escherichia coli (10.1%), and SM (7.9%). Among the 990 infections caused by SM, PIHP was the most common at 72.4%, followed by bloodstream infections (14.4%) and skin/skin structure infections (6.9%). The %S and MIC50/90 values of the 4 antimicrobials tested in this study are shown in the table. Conclusion SM was the fourth most frequent cause of GN PIHP in US medical centers. MIN was the most active drug tested against SM with 99.5%S, followed by TMP-SMX (94.7%), and CAZ was the least active with 28.5%S. This study suggests that MIN may be a consideration as a treatment for infections caused by SM, with a very low resistance rate based on CLSI breakpoints. Disclosures All authors: No reported disclosures.

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