Percentage Of Susceptibility Research Articles

Antimicrobial resistance profile of Staphylococcus spp. isolates in cattle herds from Western Amazon

Staphylococcus is one of the most frequent etiological agents of bovine mastitis, causing economic losses to milk farming. This study aimed to describe the milk production and management practices in 15 herds located in three microregions of the State of Rondônia and to identify the antimicrobial resistance profile of 97 isolates of the genus Staphylococcus from these herds. The isolates were subjected to antimicrobial susceptibility tests using the agar diffusion method. Twenty-nine S. aureus isolates were selected to determine their minimum inhibitory concentration (MIC). In the farms studied, the breeding system was semi-intensive, with the Girolando breed being predominant. Milking was performed predominantly using a mechanical milking system (86.7%), twice a day (66.7%), in the presence of the calf (53.8%). The average number of lactating cows in the farms was 24, with an average milk production of 204.9 L d-1 and a milk productivity of 10.2 L animal-1 d-1. The use of antimicrobials for the treatment and prevention of bovine mastitis was reported for all properties, and therapy for dry cows was adopted in 80% of the herds. The percent susceptibility to antimicrobials ranged from 85.5% to 100% for S. aureus, 22.2% to 88.9% for coagulase-positive staphylococci (CPS), and 69.2% to 100% for coagulase-negative staphylococci (CNS), with the highest resistance frequencies for penicillin, ampicillin, and tetracycline. Among the S. aureus isolates, 100% susceptibility to oxacillin, cefalexin, and gentamicin was observed, and among the CNS isolates, 100% susceptibility to gentamicin was observed. None of the antimicrobials tested showed 100% in vitro effectiveness for CPS. CPS and CNS presented lower percentages of susceptibility to penicillin, ampicillin, and tetracycline than the S. aureus isolates. Twelve resistance patterns were detected, six of which were multiresistance patterns. The most prevalent resistance patterns were penicillin and ampicillin (PEN-AMP) and penicillin, ampicillin, and tetracycline (PEN-AMP-TET). Results of the MIC assay revealed that all 29 S. aureus isolates were susceptible to cephalothin, cefoxitin, tetracycline, and erythromycin, whereas 25 (86.2%) were susceptible to penicillin.

Determination of Anti-Pseudomonal Activities of Cocoa (Theobroma cacao) Pod Husk using Time-Kill-Test and Agar-Well Diffusion Techniques

Aim: To determine the antimicrobial effectiveness of cocoa pod husk against P. aeruginosa.
 Study Design: An experimental research
 Place and Duration of Study: Department of Medical Microbiology, Olabisi Onabanjo University Teaching Hospital, Sagamu, Ogun State, Nigeria, between June 2015 and Sept. 2016.
 Materials and Methods: Seventy-seven (77) isolates of P. aeruginosa obtained from three (3) teaching hospitals were involved in this study. Cocoa pod husk was processed into crude extract and its effectiveness against the isolates of P. aeruginosa were examined using agar well diffusion, time-kill test techniques and Anova.
 Results: The percentage susceptibility of P. aeruginosa to Cocoa pod husk at 500 mg/mL and 250 mg/mL inhibited all the P. aeruginosa but only 14.29% were sensitive at a lower concentration of 31.25 mg/mL. Moreover, the comparison between the broth micro and macro dilution method of determining the MIC of cocoa pod husk against P. aeruginosa highlighted a significant decrease in the mean MIC value of the broth micro dilution method when compared with the broth macro dilution technique (T=13.519, P<0.05). The time kill test emphasized that P. aeruginosa was killed at a lower concentration of 62.5mg/ml at 150mins of introduction in to the Cocoa pod husk suspension.
 Conclusion: This study revealed that the Cocoa pod husk possesses antibacterial properties. An increase in the concentration of cocoa pod husk increased its antibacterial activity against Pseudomonas aeruginosa. Moreover, the broth micro dilution technique is sensitive for determining the anti-pseudomonal activity.

1063. ARGONAUT-V: Susceptibility of Multidrug-Resistant (MDR) Pseudomonas aeruginosa to Cefepime-Taniborbactam

1063. ARGONAUT-V: Susceptibility of Multidrug-Resistant (MDR) <i>Pseudomonas aeruginosa</i> to Cefepime-Taniborbactam

1011. Geospatial Analysis of Antibiotic Susceptibility in Wisconsin

BackgroundThe global threat of antimicrobial resistance (AMR) varies regionally. Regional differences may be related to socio-economic factors such as the Area Deprivation Index (ADI) score. Our hypothesis is that AMR spatial distribution is not random. MethodsPatient level antibiotic susceptibility data was collected from three regionally distinct Wisconsin health systems (UW Health, Fort HealthCare, Marshfield Clinic Health System [MCHS]). Patient addresses were geocoded to coordinates and joined with US Census Block Groups. For each culture source, we included the initial E. coli isolate per patient per year with a patient address in Wisconsin. Percent susceptibility was calculated by block group. Spatial autocorrelation was determined by Global Moran’s I, which quantifies the attribute being analyzed as spatially dispersed, randomly distributed, or clustered by a range of −1 to +1. Linear regression correlated ADI to susceptibility. Hot spot analysis identified blocks with statistically significant higher and lower susceptibility (Figure 1).Figure 1. Geographic example of hot spot analysis and interpretation. ResultsThe UW Health results included more urban areas, more block groups and greater isolate geographic density (n = 44,629 E. coli, 2009-2018), compared to Fort HealthCare (n = 6,065 isolates, 2012-2018) and MCHS (50,405 isolates, 2009-2018). A positive spatially clustered pattern was identified from the UW Health data for ciprofloxacin (Moran’s I = 0.096, p = 0.005) and trimethoprim/sulfamethoxazole (TMP/SMX) susceptibility (Moran’s I = 0.180, p < 0.001; Figures 2-3). Fort HealthCare and MCHS distribution was likely random for TMP/SMX and ciprofloxacin by Moran’s I. Linear regression of ADI (scale 1-10, least to most disadvantaged) and susceptibility did not find significance, but susceptibility was lower in more disadvantaged block groups. At the local level, we identified hot and cold spots with 90%, 95%, and 99% confidence, with more hot spots in rural regions.Figure 2. Results from Moran’s Index analysis identifying geographically clustered ciprofloxacin susceptibility results. Figure 3. Results from Moran’s Index analysis identifying geographically clustered sulfamethoxazole/trimethoprim susceptibility results. ConclusionOverall, Moran’s I analysis is more able to identify a clustered pattern in urban versus rural areas. Yet, the local hot spot results indicate that variations in antibiotic susceptibility may be more common in rural areas. The results are limited to data from patients with access to the health systems included. Disclosures Warren Rose, PharmD, MPH, Merck (Grant/Research Support)Paratek (Grant/Research Support, Advisor or Review Panel member)

1077. In Vitro Activity of Delafloxacin Agent Against Bacterial Isolates Recovered from Patients with Cancer

Abstract Background Fluoroquinolones have been used for infection prevention in patients with cancer (PWC). They are active against many Gram-negative bacilli (GNB) but are less active against Gram-positive organisms (GPO). Quinolone resistance is increasing and many institutions are using combination regimens for antimicrobial prophylaxis. We evaluated the in vitro activity of delafloxacin (DLX), a novel fluoroquinolone, and selected comparators against 560 bacterial isolates from PWC. Methods Isolates were from recent blood cultures. Susceptibility testing and time kill studies (TKS) were performed using CLSI approved methodology. Appropriate ATCC control strains were used. We calculated MIC50, MIC90, MIC ranges and percent susceptibility using FDA breakpoints when available. TKS were performed on 4 streptococcus mitis isolates at concentrations of MIC, 4x MIC, and 8x MIC. Results DLX was more active than ciprofloxacin (CIP) and levofloxacin (LEV) against methicillin-susceptible (MSSA), and resistant (MRSA) S. aureus, coagulase-negative staphylococci (CoNS), and viridans group streptococci (VGS), and had similar activity against beta-hemolytic streptococci. It also had low MICs for Bacillus species (SPP.), Listeria monocytogenes, Micrococcus spp., and Rothia spp. Overall GPO susceptibility was 73% to DLX, 42% to CIP, and 52% to LEV. The activity of DLX against Enterobacterales was similar to CIP and LEV. All 3 agents had moderate activity against Citrobacter spp., and non-MDR P. aeruginosa. Notably, all 3 quinolones had poor activity against E. coli, P. mirabilis, and MDR P. aeruginosa, all common pathogens in PWC. All 3 had low MICs for Acinetobacter spp. DLX and LEV achieved peak bactericidal activity at 6-8 h against all 4 VGS isolates (maximum activity at 8x MIC) but this was not always sustained at 24 h. Table 1. Percent Susceptibility of selected Gram-positive isolates to Delafloxacin, Ciprofloxacin and Levofloxacin Table 2. Percent Susceptibility of selected Gram-negative isolates to Delafloxacin, Ciprofloxacin and Levofloxacin Figure 1. Bactericidal Activity of DLX at 1x , 4x, and 8x MIC against VGS - Time Kill Study Conclusion DLX is more active than CIP and LEV against many GPO from PWC (including S. aureus and VGS), but like these agents there are significant gaps in its coverage against GNB. It is probably not suitable as a single agent for antimicrobial prophylaxis in high-risk PWC. The current practice of combining a quinolone with a beta-lactam probably still represents the best option in PWC who need prophylaxis. Disclosures Kenneth Rolston, MD, Tetraphase Pharmaceuticals (Grant/Research Support)

1245. In Vitro Activities of Ceftaroline and Comparator Agents Against Bacterial Pathogens Collected from Patients with Skin and Skin Structure Infections: ATLAS Global Surveillance Program 2012-2019

BackgroundCeftaroline fosamil, the prodrug of ceftaroline, is a parenteral cephem approved for the treatment of patients with skin and skin structure infections (SSSIs) caused by Staphylococcus aureus (both methicillin-susceptible [MSSA] and methicillin-resistant [MRSA] isolates), β-hemolytic streptococci (Streptococcus pyogenes, S. agalactiae, S. dysgalactiae), and select species of Enterobacterales (Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca). The current study is part of the ATLAS (Antimicrobial Testing Leadership and Surveillance) program and evaluated the current activities of ceftaroline and comparator agents against commonly encountered bacterial isolates associated with SSSIs.MethodsFrom 2012 to 2019 the ATLAS program received 124,694 bacterial isolates that had been cultured by 493 clinical laboratories in 71 countries from samples of patients diagnosed with SSSIs. All isolates were transported to IHMA, (Schaumburg, IL, USA) where their identities were confirmed using MALDI-TOF mass spectrometry and antimicrobial susceptibility testing performed following standardized CLSI broth microdilution methodology (M07). Percent susceptibilities were determined using 2021 CLSI MIC breakpoints. Phenotypic extended-spectrum β-lactamase (ESBL) screening and confirmatory testing were performed using the CLSI M100 method.ResultsThe in vitro activity of ceftaroline is summarized in the following table. Overall, >99.9% of MSSA and 92.8% of MRSA from SSSI were susceptible to ceftaroline (MIC ≤1 µg/ml); 7.1% of MRSA isolates were ceftaroline-susceptible dose-dependent (MIC 2-4 µg/ml) with greatest proportion being from Chile (53.3% of 392 isolates), S. Korea (29.3% of 321 isolates), and China (24.7% of 652 isolates). Twelve ceftaroline-resistant MRSA were observed, consisting of 11 of 109 isolates from Thailand (10.1%) and 1 of 161 from China (0.6%). All S. pyogenes and 88.0% of ESBL-negative Enterobacterales were susceptible to ceftaroline.Results Table ConclusionCeftaroline continues to demonstrate potent in vitro activity against clinically relevant pathogens associated with SSSIs.Disclosures Meredith Hackel, PhD MPH, IHMA (Employee)Pfizer, Inc. (Independent Contractor) Gregory Stone, PhD, AztraZeneca (Shareholder, Former Employee)Pfizer, Inc. (Employee) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor)

1260. In Vitro Activity of Eravacycline Against Clinically Significant Bacteria Isolated from Patients with Cancer

Abstract Background Bacterial infections are common in patients with cancer (PWC). Many bacteria have developed resistance to currently used antibiotics, posing therapeutic challenges. we evaluated the in vitro activity of eravacycline (a novel fluorocycline) against clinical bacteria recently (2018-2019) isolated from PWC. Methods All 565 isolates tested were from blood cultures. CLSI approved broth microdilution method was used. Appropriate ATCC controls were included. MIC50, MIC90, MIC ranges and percent susceptibility calculations were made using FDA breakpoints when available. Eravacycline susceptibility breakpoint for most Gram-positive organisms (GPO) is ≤ 0.06 mg/L and for Enterobacterales is ≤ 0.5 mg/L. Results Eravacycline had potent activity against Staphylococcus aureus (methicillin-susceptible and resistant strains), oxacillin-susceptible coagulase-negative staphylococci (CoNS) including Staphylococcus lugdunensis, viridans group streptococci, beta-hemolytic streptococci. Streptococcus pneumoniae. Bacillus spp., Corynebacterium spp., and Micrococcus spp. It was slightly less active against oxacillin-resistant CoNS, and vancomycin-susceptible Enterococcus faecalis (MIC90 0,125 mg/L respectively) and was moderately active against vancomycin-resistant Enterococcus faecium (MIC50, 0.06, and MIC90. 0.25 mg/L). Eravacycline had potent activity against Escherichia coli (including ESBL producing strains), Citrobacter spp., and non-ESBL Klebsiella spp. Eravacycline inhibited 83% of ESBL positive K. pneumoniae, 83% of Enterobacter cloacae, and 80% of carbapenem-resistant Enterobacteriaceae (CRE) isolates at ≤ 0.5 mg/L. The presence of ESBLs increased MIC90 value no more than 2 fold. Eravacycline was also active against many non-fermentative GNB (Achromobacter spp., Acinetobacter spp., Sphingomonas paucimobilis, and Stenotrophomonas maltophilia). Table 1. Percent Susceptibility of Gram-negative isolates to Eravacycline Table 2. Percent Susceptibility of Gram-positive isolates to Eravacycline Conclusion Our data demonstrate that eravacycline has promising activity against clinically significant bacterial pathogens isolated from PWC including many drug resistant strains such as CRE and non--fermentative GNB. it might play an important role in the treatment of bacterial infections in PWC and warrants clinical evolution in this setting. Disclosures Samuel L. Aitken, PharmD, MPH, BCIDP, Melinta Therapeutoics (Individual(s) Involved: Self): Consultant, Grant/Research Support Kenneth Rolston, MD, Tetraphase Pharmaceuticals (Grant/Research Support)

155. In Vitro Evaluation of Delafloxacin Activity Against Contemporary US Isolates from Community-Acquired Pneumonia and Community-Acquired Lower Respiratory Tract Infections: Results from the SENTRY Antimicrobial Surveillance Program (2014-2020)

155. <i>In Vitro</i> Evaluation of Delafloxacin Activity Against Contemporary US Isolates from Community-Acquired Pneumonia and Community-Acquired Lower Respiratory Tract Infections: Results from the SENTRY Antimicrobial Surveillance Program (2014-2020)

1055. ARGONAUT-IV: Susceptibility of Carbapenem-resistant Klebsiellae to Ceftibuten/VNRX-5236

1055. ARGONAUT-IV: Susceptibility of Carbapenem-resistant <i>Klebsiellae</i> to Ceftibuten/VNRX-5236

133. ARGONAUT-III: Susceptibility of Carbapenem-resistant Klebsiellae to Cefepime-Taniborbactam

133. ARGONAUT-III: Susceptibility of Carbapenem-resistant <i>Klebsiellae</i> to Cefepime-Taniborbactam

Antibiotic Use and Resistance at Intensive Care Unit of a Regional Public Hospital in Bali: A 3-Year Ecological Study

Antibiotic resistance at Intensive Care Unit (ICU) has been impacted by several factors, including high utilization and selectivity. The consumption rate and its selective pressure appear very extensive, with regular opportunities for cross-transmissions. In addition, ICU patients are susceptible to carriage acquisition and subsequent infections with high resistant bacteria. Therefore, this study investigates the relationship between the use and resistance of antibiotics in the ICU of a regional public hospital. The results potentially serve as confirmations for planning programs necessary to control ICU-related antibiotic consumption levels. This ecological analysis was also based on inpatient retrospective data from a regional public hospital in Bali from 2017–2019. Subsequently, the amount of intake expressed as daily doses (DDDs) per 100 patient days, and percentage of resistant bacterial isolates were examined using Spearman rank correlation. The largest segment of the antibiotics was determined by drug utilization 90% (DU90%) and the phenotypic class was defined by Centers for Disease Control and Prevention (CDC). Similarly, the most predominantly applied antibiotics were levofloxcacin, ceftriaxone, ampicillin, cefotaxime, ciprofloxacin, ampicillin-sulbactam and gentamycin. Meanwhile, the major gram-negative bacteria were Acinetobacter baumannii, Enterobacter cloacae, Enterococcus faecalis, Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa. Furthermore, 5 multi drug resistant (MDR) bacteria were observed, including A. baumannii, E. cloacae, E. coli, K. pneumonia and P. aeruginosa, while A. baumannii and E. cloacae occurred as carbapenem resistant (CR) and extended-spectrum cephalosporin-resistant (ESCR), respectively. However, only E. coli showed a negative significant correlation between antibiotic utilization and the percentage of ICU bacterial sensitivity (r=–0,543; p=0,024). Therefore, higher consumption of antibiotics decreases its percentage susceptibility.

In vitro activity of the novel siderophore cephalosporin, cefiderocol, in Gram-negative pathogens in Europe by site of infection

ObjectivesWe assessed the activity of the novel siderophore cephalosporin, cefiderocol and selected other antibacterial agents against Gram-negative bacterial isolates in Europe. MethodsIsolates were obtained between 2013 and 2018 from European countries participating in the SIDERO-WT and SIDERO-Proteeae multinational surveillance studies. Isolates were categorised by infection site, focusing on bloodstream infections, hospital-acquired/ventilator-associated bacterial pneumonia (HABP/VABP), complicated intra-abdominal infections and complicated urinary tract infections. Cefiderocol activity was compared with ceftazidime–avibactam, ceftolozane–tazobactam, colistin and meropenem using standard susceptibility testing methods. European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints were used to interpret susceptibility data. ResultsIsolates (n = 20 911) were collected from 145 sites in 24 countries in Europe, the highest proportion (34%) being from patients with HABP/VABP. Enterobacterales (66.6% of isolates) were more frequent than glucose non-fermenting species (33.4%) overall, with some differences between infection sites. Across all infection sites, the MIC50/MIC90 for cefiderocol was ≤0.5/≤2 mg/L for Enterobacter spp., ≤0.25/<2 mg/L for Klebsiella spp., 0.12/2 mg/L for Acinetobacter spp., ≤0.25/1 mg/L for Pseudomonas aeruginosa and ≤0.12/≤0.5 mg/L for Stenotrophomonas maltophilia. Across all infection sites, cefiderocol MICs were ≤2 mg/L for ≥96% of Enterobacter spp., ≥95% of Klebsiella spp., ≥90% of Acinetobacter spp. and ≥99% of Pseudomonas aeruginosa and Stenotrophomonas maltophilia isolates. Cefiderocol maintained high activity in carbapenem-resistant isolates, and the difference in activity between carbapenem-resistant (percentage susceptibility at EUCAST breakpoint: E. coli 77.8%, Klebsiella spp. 69.2%, Pseudomonas aeruginosa 97.5%, Acinetobacter spp. 90.7%, Stenotrophomonas maltophilia 99.6%) and carbapenem-susceptible (percentage susceptibility at EUCAST breakpoint: E. coli 99.4%, Klebsiella spp. 98.0%, Pseudomonas aeruginosa 99.7%, Acinetobacter spp. 94.9%) isolates was lower for cefiderocol than other agents. ConclusionsCefiderocol had excellent activity against all Gram-negative species, independent of key infection site and carbapenem MIC. Cefiderocol is a useful addition to the therapeutic options available for these difficult-to-treat infections.

Comparative in vitro effectiveness of ceftolozane/tazobactam against pediatric gram-negative drug-resistant isolates

Ceftolozane/tazobactam (C/T), a cephalosporin/beta-lactamase inhibitor combination, was evaluated in vitro vs. 10 comparators against 299 pediatric extended-spectrum-cephalosporin-resistant or carbapenem-resistant (ESC-R/CR) Gram-negative Enterobacteriaceae from three freestanding pediatric centers. Isolates were from urine or other sterile sites of children and adolescents through 21 years of age. Susceptibilities were assayed by microbroth dilution via custom Sensititre plates (Thermo Fisher Scientific). Susceptibility was determined using the Sensititre Vizion® system (Thermo Fisher Scientific). Susceptibility breakpoint criteria were those of the Clinical and Laboratory Standards Institute (CLSI) for 2017, except for colistin (EUCAST 2019). Overall, 87.5% isolates were C/T susceptible (MIC ≤2 μg/ml; MIC50/90, 0.25/4 μg/ml). Susceptibility to C/T was detected more frequently as compared to all other antimicrobials tested except for colistin (95.4%) and meropenem (97.4%). Percent susceptibility to C/T was high for E. coli (91%) and Klebsiella spp. (73.3%). C/T demonstrated good in-vitro activity and high potency against most beta-lactam resistant pediatric Enterobacteriaceae from three geographically diverse U.S. regions.

The host status of glyphosate-tolerant soybean genotypes to Meloidogyne incognita and Pratylenchus infection

The host status of South African adapted, genetically modified (GM) glyphosate-tolerant soybean genotypes to root-knot (field and glasshouse) and lesion (field) nematodes were assessed. Analyses of root and soil samples of 29 genotypes (collected from seven production areas during the 2014/15 season) enabled the identification of nine plant-parasitic nematode genera and 10 species. Predominant endoparasitic genera in root samples were Meloidogyne (Meloidogyne incognita and M. javanica) and Pratylenchus (Pratylenchus brachyurus, P. zeae and P. teres). Rotylenchulus parvus was the predominant semi-endoparasite in soil, followed by Scutellonema brachyurus and Helicotylenchus sp. Only ‘PAN 1583 R’ and ‘PAN 1521 R’ maintained less than 10% of the Meloidogyne spp. densities present in roots of the most susceptible genotype, while all genotypes were susceptible to the Pratylenchus spp. The host status of 36 soybean genotypes to M. incognita infection, evaluated in two follow-up glasshouse experiments terminated 56 days after inoculation of ca. 1000 M. incognita eggs and second-stage juveniles (J2) per seedling, varied substantially for final population density (Pf), reproduction factor (Rf) and relative percentage susceptibility (%S). Only ‘PRF-GCI7’ and the resistant reference ‘LS 5995’ had Rfs < 1 for both experiments, despite higher minimum and maximum temperatures recorded for the second experiment. Continuous evaluation of soybean genotypes for their host status to predominant nematode pests and their use to reduce densities of such species in producer’s fields are crucial to enable sustainable crop production, and contribute towards food provision and security.

Bacteriological Assessment and Antibiotic Susceptibility Profile of Bacteria Recovered from &amp;lt;i&amp;gt;Clarias gariepinus&amp;lt;/i&amp;gt; Selected from Various Fish Farms in Anambra North Senatorial Zones in Anambra State, Nigeria

Fishes are cheap sources of protein and are commonly reared in artificial pond in Nigeria. Bacterial infested fishes have been a serious public health concern. This study was aimed at isolating and identifying bacteria associated with the internal organs (gills, liver, guts) of Clarias gariepinus (African Catfish) in fish ponds in Anambra North Senatorial zones in Anambra State, Nigeria, and to determine the seasonal bacterial load of the organs and antibiotic susceptibility profile of the isolates to conventional antibiotics. A total of 720 African catfish were sampled from randomly selected fish farms during rainy and dry seasons. Bacteria isolates inoculated on Blood and Nutrient agar plates were identified based on morphological and biochemical characteristics. Susceptibility of the isolates to antibiotics was carried out using the Kirby-Bauer disc diffusion method. Isolates from the fish organs include species of Vibrio, Aeromonas, Pseudomonas, Lactobacillus, Staphylococcus, Microbacterium, Serratia, Proteus, Bacillus, Streptococcus, Citrobacter and Micrococcus. Results also revealed that there was significant difference (p value Bacillus sp. was the most abundant gram positive bacterium in the organs of the fish samples during the rainy and dry season, while Citrobacter sp., a gram negative organism, was relatively abundant in the liver and gut. Percentage susceptibility of the bacteria to antibiotics was highest with vancomycin (100%) and least with erythromycin (75.0%). The most susceptible isolates were species of Staphylococcus, Microccoccus and Microbacterium while Bacillus sp. was the most resistant bacterium. This study has shown that high bacteria load are found in the internal organs of the fish and a good number of the bacteria are resistant to some of the antibiotics tested. There is, therefore, need for adherence to proper sanitary measures to avoid bacterial contamination of fish.

1600. Closing the gap on moxifloxacin breakpoints for Stenotrophomonas maltophilia

BackgroundMoxifloxacin (MOX) has in vitro activity against Enterobacterales and Stenotrophomonas maltophilia (SM). Although MOX commonly displays lower minimum inhibitory concentration (MIC)50/90 values against SM when compared to levofloxacin, there are currently no established MOX breakpoints for treatment of SM. The Clinical and Laboratory Standards Institute (CLSI) has established interpretive categories and MIC breakpoints for levofloxacin (S ≤2µg/ml) against SM. The US Food and Drug Administration and European Committee on Antimicrobial Susceptibility Testing provide MOX breakpoints for Enterobacterales with susceptible MICs represented at ≤ 2 µg/mL and ≤ 0.25 µg/mL, respectively. The purpose of this study was to evaluate MOX MIC distribution against SM strains recovered from clinical specimens.MethodsClinical samples from patients with suspected infection during calendar year 2018 and 2019 were processed in the microbiology lab of Wake Forest Baptist Medical Center. After incubation, SM colonies were identified by MALDI-TOF system. MOX susceptibility testing was performed for these clinical isolates by gradient diffusion strip methodologies. Results were displayed as MIC (µg/mL) without interpretation. MIC50/90 and susceptibility rates at potential breakpoints were calculated.ResultsA total of 211 isolates were tested, 112 from 2018 and 99 from 2019. MOX MIC50 and MIC90 for all isolates was 0.25 µg/mL and 2 µg/mL, respectively. The range of MIC distribution was ≤ 0.006 µg/mL to ≥ 64 µg/mL. Percent susceptibilities at incremental MICs, including established MOX breakpoints against Enterobacterales and established levofloxacin breakpoints against SM, are represented in Table 1. MIC distribution was plotted in Figure 1.Table 1. Susceptibility rates of S. maltophilia to moxifloxacin at theoretical breakpoints Figure 1. Moxifloxacin MIC Distribution against All S. maltophilia Isolates ConclusionWith no established breakpoint, these data represent one of the largest samples of MOX MICs against SM in the United States. Using the CLSI breakpoint for levofloxacin in SM (MIC of ≤2ug/ml) the overall susceptibility rate is 93%. This finding highlights the importance of performing susceptibility testing to this agent by the microbiology laboratory and the critical need for MOX breakpoints in SM.Disclosures Tyler J. Stone, PharmD, Paratek (Research Grant or Support) John Williamson, PharmD, Paratek (Research Grant or Support) Elizabeth Palavecino, MD, Paratek (Grant/Research Support)Paratek (Grant/Research Support)

1565. In Vitro Activities of Ceftaroline and Comparator Agents against Bacterial Pathogens Collected from Patients with Skin and Skin Structure Infections: ATLAS Global Surveillance Program 2012-2018

BackgroundCeftaroline fosamil, the prodrug of ceftaroline, is a parenteral cephem approved for the treatment of patients with skin and skin structure infections (SSSIs) caused by Staphylococcus aureus (both methicillin-susceptible [MSSA] and methicillin-resistant [MRSA] isolates), β-hemolytic streptococci (Streptococcus pyogenes, Streptococcus agalactiae), and select species of Enterobacterales (Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca). The current study is part of the ATLAS (Antimicrobial Testing Leadership and Surveillance) program and evaluated the current activities of ceftaroline and comparator agents against commonly encountered bacterial isolates associated with SSSIs.MethodsFrom 2012 to 2018 the ATLAS program received 90,119 bacterial isolates that had been cultured by 370 clinical laboratories in 56 countries from samples of patients diagnosed with SSSIs. All isolates were transported to IHMA, Inc., (Schaumburg, IL, USA) where their identities were confirmed using MALDI-TOF mass spectrometry and antimicrobial susceptibility testing performed following standardized CLSI broth microdilution methodology (M07). Percent susceptibilities were determined using 2020 CLSI MIC breakpoints. Phenotypic ESBL screening and confirmatory testing were performed using the CLSI M100 method.ResultsThe in vitro activity of ceftaroline is summarized in the following table. Overall, 100% of MSSA and 93.8% of MRSA from SSSI were susceptible to ceftaroline (MIC ≤1 µg/ml); 6.2% of MRSA isolates were ceftaroline -susceptible dose-dependent (MIC 2-4 µg/ml) with greatest proportion being from Chile (57.1% of 1,669 isolates), Thailand (36.5% of 2,318 isolates), and S. Korea (29.3% of 1,231 isolates). No ceftaroline-resistant MRSA were observed. All S. pyogenes and 88.5% of ESBL-negative Enterobacterales were also susceptible to ceftaroline.Table ConclusionCeftaroline continues to demonstrate potent in vitro activity against clinically relevant pathogens associated with SSSIs.Disclosures Greg Stone, PhD, AztraZeneca (Shareholder, Former Employee)Pfizer, Inc. (Employee) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Consultant)Shionogi & Co., Ltd. (Independent Contractor)

1594. Antimicrobial Resistance Monitoring through the ATLAS Global Surveillance Program 2012-2018

BackgroundAntimicrobial resistance is an increasingly serious threat to global public health. The Antimicrobial Testing Leadership and Surveillance (ATLAS) program has provided reliable, global, regional and local in vitro susceptibility data, including mechanisms of resistance, since 2004. In this analysis, data from the ATLAS program are used to measure the in vitro activity of several key gram-negative/gram-positive agents against major global pathogens.MethodsA total of 251,837 gram-negative and 132,363 gram-positive non-duplicate, clinical isolates were collected from multiple infection sources from 743 unique sites in 74 countries during 2012-2018 in the ATLAS program. Identification was confirmed to the species level using MALDI-TOF spectrometry. Only one clinically relevant causative isolate per patient was accepted into the study. MICs were determined by broth microdilution following CLSI guidelines and interpreted using 2020 CLSI breakpoints. Phenotypic ESBL screening and confirmatory testing were performed using the CLSI M100 method.ResultsThe in vitro activities of selected antimicrobial agents are provided in the table below. Based on percent susceptibility, ceftazidime-avibactam, amikacin, tigecycline, meropenem, and ceftolozane-tazobactam were the most active agents against most gram-negative isolates. The CRE rate among Enterobacterales isolates was 3.2%, with tigecycline and ceftazidime-avibactam the most active among this resistant subgroup. Ceftazidime-avibactam, ceftolozane-tazobactam, and amikacin were the most active agents against Pseudomonas aeruginosa. Ceftaroline, linezolid, tigecycline and vancomycin all showed good activity against gram-positive isolates.Table ConclusionCeftazidime-avibactam, ceftolozane-tazobactam, tigecycline, meropenem, and amikacin all showed good activity against a global collection of Enterobacterales. Ceftaroline, tigecycline, linezolid and vancomycin all exhibited excellent activity against gram-positive isolates. Continued monitoring of susceptibility patterns among common pathogens will provide useful information for determining treatment strategies.DisclosuresDaniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Consultant)Shionogi & Co., Ltd. (Independent Contractor) Michael Dowzicky, MS, M.T. A.S.C.P., Pfizer, Inc. (Employee)

1184. Activity of anti-pseudomonal antibiotics among all Pseudomonas aeruginosa (PSA) at an academic medical health system, including β-lactam, multi-drug (MDR) and extensively drug resistant (XDR) strains

BackgroundPSA with MDR and XDR are a growing threat, and appropriate initial treatment of this organism is critical. C/T is a novel antibiotic with broad gram-negative in vitro susceptibility among surveillance studies. However comprehensive susceptibility analyses of C/T among PSA clinical isolates in comparison with other anti-PSA antibiotics remain limited, since routine clinical C/T susceptibility testing is not typically performed.MethodsThis study assessed all adult inpatient cultures positive for PSA from 32 months at an academic health system. Antimicrobial susceptibility was prospectively performed using Kirby Bower disk diffusion and interpreted by BIOMIC V3 during routine clinical care. Initial susceptibility testing included C/T along with amikacin, aztreonam, cefepime, ciprofloxacin, doripenem, gentamicin, imipenem, meropenem, piperacillin/tazobactam, and tobramycin. MDR and XDR isolates were identified using established definitions. The primary outcome was to quantify C/T resistant PSA (includes intermediate and resistant strains). Secondary outcomes were to determine resistance to other anti-PSA antibiotics and to identify C/T activity among isolates with MDR, XDR and pan-β-lactam resistance (PBLR = all β-lactams except C/T).ResultsA total of 2990 PSA isolates from 2339 cultures in 1311 individual patients were collected. Most cultures were from the lung (45%), followed by urine (30%), and body fluids (10%). For the primary outcome, 121/2990 (4%) of PSA isolates were C/T resistant. All PSA blood cultures were susceptible to C/T. Table 1 summarizes in vitro activity of all anti-PSA agents evaluated. C/T had the greatest percent susceptibility across all culture locations including MDR/XDR PSA isolates with median MICs of 8 µg/mL. For PBLR strains 35/66 (53%) were susceptible to C/T with a median MIC of 8 µg/mL.Table 1 ConclusionC/T susceptibility testing during routine care over a 2.5-year period revealed 96% susceptibility among PSA. C/T showed the highest susceptibility among all anti-PSA antibiotics for all culture locations and for MDR and XDR isolates. Given the high rates of resistance to traditional anti-PSA agents, the value of new agents with high rates of in vitro susceptibility in the gram-negative armamentarium is high.DisclosuresWarren Rose, PharmD, MPH, Merck (Grant/Research Support)Paratek (Grant/Research Support) Janet Radaatz, PharmD, Merck (Employee) Laura A. Puzniak, PhD, Merck (Employee) Ryan J. Dillon, MSc, Merck & Co., Inc., (Employee)

157. A Multidisciplinary Approach to Carbapenem Stewardship at a Large Community Hospital in Brooklyn, New York

BackgroundCarbapenem-resistant gram-negative organisms are a continuously mounting threat, underscoring the need for effective antimicrobial stewardship interventions to improve the use of carbapenems. We sought to implement several multidisciplinary antimicrobial stewardship interventions beginning in January 2019 in an effort to reduce unnecessary meropenem use and the incidence of carbapenem-resistant gram-negatives.MethodsProspective audit and feedback was utilized daily in combination with weekly stewardship rounds between an Infectious Diseases pharmacist and physician in the Intensive Care Units. A second Infectious Diseases physician attended weekly interdisciplinary rounds on meropenem high-use units. Meropenem Days of Therapy (DOT) per 1,000 patient days and the incidence of meropenem resistant Pseudomonas aeruginosa and Klebsiella pneumoniae were compared by the chi-square test of proportions.ResultsBetween 2018 and 2019 the institution’s meropenem DOT per 1,000 patient days decreased 33%, from 57 to 38 days per 1,000 patient days (difference, 19 days per 1,000 patient days; p< 0.001). In the hospital antibiogram, the meropenem susceptibility of Pseudomonas aeruginosa over the same time period increased from 71% to 77% of isolates (difference, 6%; p = 0.009). A non-significant decrease in the susceptibility of meropenem to Klebsiella pneumoniae was also observed from 92 to 90% (difference, 2%: p = 0.1658).ConclusionThese data support the need for antimicrobial stewardship efforts targeting broad-spectrum antimicrobials such as meropenem. In the setting of a sustained decrease in meropenem use over 12 months, we observed a significant improvement in the percent susceptibility rate of Pseudomonas aeruginosa to meropenem for the first time in five years.Disclosures All Authors: No reported disclosures