scholarly journals Susceptibility of Bacterial Endophthalmitis Isolates to Vancomycin, Ceftazidime, and Amikacin

2021 ◽  
Author(s):  
Kuan-Jen Chen ◽  
Ming-Hui Sun ◽  
Chiun-Ho Hou ◽  
Hung-Chi Chen ◽  
Yen-Po Chen ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Vision Loss ◽  
Multidrug Resistant ◽  
Coagulase Negative Staphylococci ◽  
Gram Positive ◽  
In Vitro Susceptibility ◽  
Gram Negative ◽  
Tertiary Referral Center ◽  
Bacterial Endophthalmitis

Abstract Bacterial endophthalmitis is a rare intraocular infection, and prompt administration of intravitreal antibiotics is crucial for preventing severe vision loss. The retrospective study is to investigate the in vitro susceptibility to the antibiotics vancomycin, amikacin, and ceftazidime of bacterial endophthalmitis isolates in specimens at a tertiary referral center from January 1996 to April 2019 in Taiwan. Overall, 450 (49.9%) isolates were gram positive, 447 (49.6%) were gram negative, and 4 (0.4%) were gram variable. In gram-positive isolates, coagulase-negative staphylococci were the most commonly cultured bacteria (158, 35.1%), followed by streptococci (100, 22.2%), enterococci (75, 16.7%), and Staphylococcus aureus (70, 15.6%). In gram-negative isolates, they were Klebsiella pneumoniae (166, 37.1%) and Pseudomonas aeruginosa (131, 29.3%). All gram-positive organisms were susceptible to vancomycin, with the exception of one Enterococcus faecium isolate (1/450, 0.2%). Of the gram-negative isolates, 96.9% and 93.7% were susceptible to ceftazidime and amikacin, respectively. Nine isolates (9/447, 2.0%) were multidrug-resistant gram-negative bacteria, comprising Klebsiella pneumoniae (4/164, 2.4%), Acinetobacter baumannii (2/3, 67%), and Stenotrophomonas maltophilia (3/18, 17%). In conclusion, in vitro susceptibility testing revealed that vancomycin remains the suitable antibiotic treatment for gram-positive endophthalmitis. Ceftazidime and amikacin provide approximately the same degree of gram-negative coverage. Multidrug-resistant bacterial endophthalmitis was uncommon.

scholarly journals Susceptibility of bacterial endophthalmitis isolates to vancomycin, ceftazidime, and amikacin

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kuan-Jen Chen ◽  
Ming-Hui Sun ◽  
Chiun-Ho Hou ◽  
Hung-Chi Chen ◽  
Yen-Po Chen ◽  
...  
Keyword(s):  
Vision Loss ◽  
Multidrug Resistant ◽  
Coagulase Negative Staphylococci ◽  
Gram Positive ◽  
In Vitro Susceptibility ◽  
Gram Negative ◽  
Tertiary Referral Center ◽  
Bacterial Endophthalmitis ◽  
Severe Vision Loss

AbstractBacterial endophthalmitis is a rare intraocular infection, and prompt administration of intravitreal antibiotics is crucial for preventing severe vision loss. The retrospective study is to investigate the in vitro susceptibility to the antibiotics vancomycin, amikacin, and ceftazidime of bacterial endophthalmitis isolates in specimens at a tertiary referral center from January 1996 to April 2019 in Taiwan. Overall, 450 (49.9%) isolates were Gram positive, 447 (49.6%) were Gram negative, and 4 (0.4%) were Gram variable. In Gram-positive isolates, coagulase-negative staphylococci were the most commonly cultured bacteria (158, 35.1%), followed by Streptococci (100, 22.2%), Enterococci (75, 16.7%), and Staphylococcus aureus (70, 15.6%). In Gram-negative isolates, they were Klebsiella pneumoniae (166, 37.1%) and Pseudomonas aeruginosa (131, 29.3%). All Gram-positive organisms were susceptible to vancomycin, with the exception of one Enterococcus faecium isolate (1/450, 0.2%). Of the Gram-negative isolates, 96.9% and 93.7% were susceptible to ceftazidime and amikacin, respectively. Nine isolates (9/447, 2.0%) were multidrug-resistant Gram-negative bacteria, comprising K. pneumoniae (4/164, 2.4%), Acinetobacter baumannii (2/3, 67%), and Stenotrophomonas maltophilia (3/18, 17%). In conclusion, in vitro susceptibility testing revealed that vancomycin remains the suitable antibiotic treatment for Gram-positive endophthalmitis. Ceftazidime and amikacin provide approximately the same degree of Gram-negative coverage. Multidrug-resistant bacterial endophthalmitis was uncommon.

scholarly journals Cefepime/tazobactam as a new treatment option for multidrug resistant gram negative bacilli

2019 ◽  
Vol 7 (6) ◽  
pp. 2278
Author(s):  
Roshni Agarwal ◽  
Vaibhav Agarwal ◽  
Anjali Tewari ◽  
Parwati Upadhyay
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Klebsiella Pneumoniae ◽  
Multidrug Resistant ◽  
Diffusion Method ◽  
Resistant Bacteria ◽  
In Vitro Susceptibility ◽  
Gram Negative ◽  
E Coli ◽  
New Treatment

Background: Every time an antibiotic is used, whether appropriately or not, the probability of the development and spread of antibiotic resistant bacteria is increased. Thus, multidrug resistant bacteria particularly ESBL (Extended spectrum β­lactamase), Amp C and carbapenemases producing gram negative bacilli have emerged as a major health problem all over the world. Considering new treatment options as a carbapenems sparing and resistance prevention modality, this study was aimed to know the in vitro susceptibility pattern of Cefepime/Tazobactam (CPM/TZ) in comparison to other β-Lactam/ β-Lactamase inhibitors (BL/BLI) and carbapenems against GNB.Methods: A prospective study was conducted on all clinical samples received for a period of about 1 year. Identification and susceptibility of all isolates was done by Vitek 2 Compact system. Susceptibility of CPM/ TZ was done by disc diffusion method on the basis of CLSI guidelines. Both fermenters (E. coli and Klebsiella pneumoniae) and non-fermenters (Acintobacter baumanii and Pseudomonas aeruginosa) were included in the study.Results: Out of 550 GNB isolates the most common was E. coli (61.8%), Acintobacter baumanii (16%), Klebsiella pneumoniae (14.9%) and Pseudomonas aeruginosa (7.3%). Cefepime/tazobactam had a much higher susceptibility of 68% compared to cefepime (28%). Among the BL/BLI combinations tested cefepime/tazobactam (68%) showed the maximum percentage of susceptibility followed by cefoperazone/sulbactam (61.5%) and piperacillin/tazobactam (57.6%). Amongst all GNB isolates cefepime/tazobactam (68%) sensitivity was very much comparable to imipenem (71.8%) and meropenem (69.6%).Conclusions: CPM/TZ exhibited the best in vitro activity in comparison to the other BL/BLI. This new combination of cefepime/tazobactam appears to be a promising alternative therapeutic option to carbapenems. Clinical studies are needed to confirm this in vitro study result.

scholarly journals 519. Multidrug-resistant Gram-Negative Bacteremia in Pediatric Patients: Is It Time to Change to Empiric Meropenem?

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S250-S250
Author(s):  
Kanokporn Mongkolrattanothai ◽  
Leslie Stach ◽  
Regina Orbach
Keyword(s):  
Antimicrobial Agents ◽  
Pediatric Patients ◽  
Multidrug Resistant ◽  
Suspected Sepsis ◽  
In Vitro Susceptibility ◽  
Gram Negative ◽  
Gram Negative Bacteremia ◽  
Delayed Initiation ◽  
Poor Outcomes

Abstract Background The rise of antimicrobial resistance among gram-negative (GN) pathogens has been dramatic nationally. Delayed initiation of active antimicrobial agents has been associated with poor outcomes. We aimed at evaluating the prevalence and treatment of multi-drug-resistant gram-negative (MDR-GN) bacteremia in our pediatric patients. Methods All episodes of GN bacteremia from 2017–2018 at our institution were retrospectively reviewed. GN defined as MDR in our study were carbapenem-resistant organisms (CRO), extended-spectrum β-lactamase (ESBL) producers, and GN that were resistant to cefepime and ≥2 classes of non-cephalosporin antimicrobial agents. Stenotrophomonas maltophilia was excluded. Ineffective empirical treatment (IET) is defined as an initial antibiotic regimen that is not active against the identified pathogen[s] based on in vitro susceptibility testing results. Results A total of 292 episodes of GN bacteremia were identified and 6 S. maltophilia were excluded. Of these, 29 bacteremic episodes in 26 patients were caused by MDR-GN organisms including 18 ESBL, 7 CRO, 1 ESBL and CRO, 3 non-ESBL/non-CRO cefepime-resistant MDR-GN. None of the CRO had carbapenemase genes detected. However, there was a patient with multiple sites of infection simultaneously with non-NDM CR Acinetobacter bacteremia and NDM-mediated CR-Klebsiella ventriculitis. The annual rate of MDR-GN bacteremia increased from 8% in 2017 to 12% in 2018. Almost half (48%) of episodes were community onset. Among these, all but one had underlying medical conditions with hospital exposure and most patients had central venous devices at the time of infection. 52% (15/29) episodes of MDR-GN bacteremia had IET. Despite IET, 47% (7/15) had negative blood cultures prior to initiation of effective therapy (6 ESBL and 1 P. aeruginosa). Various antibiotic regimens were used for CRO therapy as shown in Table 1. Conclusion In our institution, MDR-GN infection is increasing. As such, empiric meropenem is currently recommended in BMT or neutropenic patients with suspected sepsis. However, empiric meropenem must be used judiciously as its widely use will lead to more selection of MDR pathogens. It is essential to continue monitoring of these MDR-GN to guide appropriate empiric regimens. Disclosures All authors: No reported disclosures.

scholarly journals In Vitro Activity of Ceftazidime-Avibactam against Isolates from Respiratory and Blood Specimens from Patients with Nosocomial Pneumonia, Including Ventilator-Associated Pneumonia, in a Phase 3 Clinical Trial

2020 ◽  
Vol 64 (5) ◽  
Author(s):  
Gregory G. Stone ◽  
Patricia A. Bradford ◽  
Margaret Tawadrous ◽  
Dianna Taylor ◽  
Mary Jane Cadatal ◽  
...  
Keyword(s):  
Nosocomial Pneumonia ◽  
Bacterial Pathogen ◽  
Multidrug Resistant ◽  
Ventilator Associated Pneumonia ◽  
Phase 3 ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type ◽  
Highly Active

ABSTRACT Nosocomial pneumonia (NP), including ventilator-associated pneumonia (VAP), is increasingly associated with multidrug-resistant Gram-negative pathogens. This study describes the in vitro activity of ceftazidime-avibactam, ceftazidime, and relevant comparator agents against bacterial pathogens isolated from patients with NP, including VAP, enrolled in a ceftazidime-avibactam phase 3 trial. Gram-positive pathogens were included if coisolated with a Gram-negative pathogen. In vitro susceptibility was determined at a central laboratory using Clinical and Laboratory Standards Institute broth microdilution methods. Of 817 randomized patients, 457 (55.9%) had ≥1 Gram-negative bacterial pathogen(s) isolated at baseline, and 149 (18.2%) had ≥1 Gram-positive pathogen(s) coisolated. The most common isolated pathogens were Klebsiella pneumoniae (18.8%), Pseudomonas aeruginosa (15.8%), and Staphylococcus aureus (11.5%). Ceftazidime-avibactam was highly active in vitro against 370 isolates of Enterobacteriaceae, with 98.6% susceptible (MIC90, 0.5 μg/ml) compared with 73.2% susceptible for ceftazidime (MIC90, >64 μg/ml). The percent susceptibility values for ceftazidime-avibactam and ceftazidime against 129 P. aeruginosa isolates were 88.4% and 72.9% (MIC90 values of 16 μg/ml and 64 μg/ml), respectively. Among ceftazidime-nonsusceptible Gram-negative isolates, ceftazidime-avibactam percent susceptibility values were 94.9% for 99 Enterobacteriaceae and 60.0% for 35 P. aeruginosa. MIC90 values for linezolid and vancomycin (permitted per protocol for Gram-positive coverage) were within their respective MIC susceptibility breakpoints against the Gram-positive pathogens isolated. This analysis demonstrates that ceftazidime-avibactam was active in vitro against the majority of Enterobacteriaceae and P. aeruginosa isolates from patients with NP, including VAP, in a phase 3 trial. (This study has been registered at ClinicalTrials.gov under identifier NCT01808092.)

Evaluation of in vitro susceptibility of Gram-positive pathogens from a tertiary care hospital in Singapore to a novel oxazolidinone, tedizolid, by a gradient diffusion method and broth microdilution

2018 ◽  
Vol 72 (2) ◽  
pp. 181-184
Author(s):  
Saugata Choudhury ◽  
Lee Kar Mun ◽  
Esme Ng Chu Xuan ◽  
Lee Shin Jia ◽  
Shawn Vasoo ◽  
...  
Keyword(s):  
Tertiary Care ◽  
Bloodstream Infections ◽  
Diffusion Method ◽  
Care Hospital ◽  
Broth Microdilution ◽  
Coagulase Negative Staphylococci ◽  
Gram Positive ◽  
In Vitro Susceptibility ◽  
Gradient Diffusion

We compared the in vitro antimicrobial activities of tedizolid and linezolid on the Sensititre broth microdilution system for Gram-positive cocci isolates (n=146) from skin and skin structure infections and bloodstream infections, bronchoalveolar lavage and sputum. These pathogens included 40 methicillin-resistant Staphylococcus aureus, 38 coagulase-negative staphylococci, 20 Enterococcus faecalis and 48 beta-haemolytic Streptococcus spp. Susceptibility was simultaneously determined for 48 vanA vancomycin-resistant enterococci isolates 2013–2016 from rectal swabs (23 E. faecalis and 25 E. faecium, of which 4 were linezolid-non-susceptible). MIC90s for tedizolid were fourfold to eightfold lower than linezolid on the Sensititre and ranged from 0.12 to 0.5 µg/mL for the different pathogen groups. All isolates were susceptible to tedizolid except two vanA E. faecium strains (MICs of 1 and 2 µg/mL, respectively). Categorical and essential agreement for tedizolid were 99.48% and 92%, respectively, between Liofilchem gradient diffusion and Sensititre methods. Overall, the drug exhibited excellent activity against the surveyed Gram-positive pathogens.

scholarly journals In Vitro Study of Antimicrobial Percutaneous Nephrostomy Catheters for Prevention of Renal Infections

2017 ◽  
Vol 61 (6) ◽  
Author(s):  
Nylev Vargas-Cruz ◽  
Ruth A. Reitzel ◽  
Joel Rosenblatt ◽  
Mohamed Jamal ◽  
Ariel D. Szvalb ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Biofilm Formation ◽  
In Vitro Study ◽  
Percutaneous Nephrostomy ◽  
Multidrug Resistant ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type ◽  
Fungal Organisms

ABSTRACT Percutaneous nephrostomy (PCN) catheters are the primary method for draining ureters obstructed by malignancy and preventing a decline of renal function. However, PCN catheter-related infections, such as pyelonephritis and urosepsis, remain a significant concern. Currently, no antimicrobial PCN catheters are available for preventing infection complications. Vascular catheters impregnated with minocycline-rifampin (M/R) and M/R with chlorhexidine coating (M/R plus CHD) have previously demonstrated antimicrobial activity. Therefore, in this study, we examined whether these combinations could be applied to PCN catheters and effectively inhibit biofilm formation by common uropathogens. An in vitro biofilm colonization model was used to assess the antimicrobial efficacy of M/R and M/R-plus-CHD PCN catheters against nine common multidrug-resistant Gram-positive and Gram-negative uropathogens as well as Candida glabrata and Candida albicans. Experimental catheters were also assessed for durability of antimicrobial activity for up 3 weeks. PCN catheters coated with M/R plus CHD completely inhibited biofilm formation for up to 3 weeks for all the organisms tested. The reduction in colonization compared to uncoated PCN catheters was significant for all Gram-positive, Gram-negative, and fungal organisms (P < 0.05). M/R-plus-CHD PCN catheters also produced significant reductions in biofilm colonization relative to M/R PCN catheters for Enterobacter spp., Escherichia coli, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, C. glabrata, and C. albicans (P < 0.05). M/R-plus-CHD PCN catheters proved to be highly efficacious in preventing biofilm colonization when exposed to multidrug-resistant pathogens common in PCN catheter-associated pyelonephritis. M/R-plus-CHD PCN catheters warrant evaluation in a clinical setting to assess their ability to prevent clinically relevant nephrostomy infections.

scholarly journals In Vitro Activities of RWJ-54428 (MC-02,479) against Multiresistant Gram-Positive Bacteria

2001 ◽  
Vol 45 (5) ◽  
pp. 1422-1430 ◽  
Author(s):  
Suzanne Chamberland ◽  
Johanne Blais ◽  
Monica Hoang ◽  
Cynthia Dinh ◽  
Dylan Cotter ◽  
...  
Keyword(s):  
Multidrug Resistant ◽  
Penicillin G ◽  
Significant Activity ◽  
Coagulase Negative Staphylococci ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Level Of Activity ◽  
Resistant Strains ◽  
High Level

ABSTRACT RWJ-54428 (MC-02,479) is a new cephalosporin with a high level of activity against gram-positive bacteria. In a broth microdilution susceptibility test against methicillin-resistant Staphylococcus aureus (MRSA), RWJ-54428 was as active as vancomycin, with an MIC at which 90% of isolates are inhibited (MIC90) of 2 μg/ml. For coagulase-negative staphylococci, RWJ-54428 was 32 times more active than imipenem, with an MIC90 of 2 μg/ml. RWJ-54428 was active against S. aureus, Staphylococcus epidermidis, and Staphylococcus haemolyticus isolates with reduced susceptibility to glycopeptides (RWJ-54428 MIC range, ≤0.0625 to 1 μg/ml). RWJ-54428 was eight times more potent than methicillin and cefotaxime against methicillin-susceptible S. aureus (MIC90, 0.5 μg/ml). For ampicillin-susceptible Enterococcus faecalis (including vancomycin-resistant and high-level aminoglycoside-resistant strains), RWJ-54428 had an MIC90 of 0.125 μg/ml. RWJ-54428 was also active against Enterococcus faecium, including vancomycin-, gentamicin-, and ciprofloxacin-resistant strains. The potency against enterococci correlated with ampicillin susceptibility; RWJ-54428 MICs ranged between ≤0.0625 and 1 μg/ml for ampicillin-susceptible strains and 0.125 and 8 μg/ml for ampicillin-resistant strains. RWJ-54428 was more active than penicillin G and cefotaxime against penicillin-resistant, -intermediate, and -susceptible strains ofStreptococcus pneumoniae (MIC90s, 0.25, 0.125, and ≤0.0625 μg/ml, respectively). RWJ-54428 was only marginally active against most gram-negative bacteria; however, significant activity was observed against Haemophilus influenzae andMoraxella catarrhalis (MIC90s, 0.25 and 0.5 μg/ml, respectively). This survey of the susceptibilities of more than 1,000 multidrug-resistant gram-positive isolates to RWJ-54428 indicates that this new cephalosporin has the potential to be useful in the treatment of infections due to gram-positive bacteria, including strains resistant to currently available antimicrobials.

scholarly journals In VitroActivity of AZD0914, a Novel Bacterial DNA Gyrase/Topoisomerase IV Inhibitor, against Clinically Relevant Gram-Positive and Fastidious Gram-Negative Pathogens

2015 ◽  
Vol 59 (10) ◽  
pp. 6053-6063 ◽  
Author(s):  
Douglas J. Biedenbach ◽  
Michael D. Huband ◽  
Meredith Hackel ◽  
Boudewijn L. M. de Jonge ◽  
Daniel F. Sahm ◽  
...  
Keyword(s):  
Bacterial Species ◽  
Dna Gyrase ◽  
Species Group ◽  
Coagulase Negative Staphylococci ◽  
Topoisomerase Iv ◽  
Gram Positive ◽  
Bacterial Dna ◽  
Gram Negative ◽  
Content Type

ABSTRACTAZD0914, a new spiropyrimidinetrione bacterial DNA gyrase inhibitor with a novel mode of inhibition, has activity against bacterial species commonly cultured from patient infection specimens, including fluoroquinolone-resistant isolates. This study assessed thein vitroactivity of AZD0914 against key Gram-positive and fastidious Gram-negative clinical isolates collected globally in 2013. AZD0914 demonstrated potent activity, with MIC90s for AZD0914 of 0.25 mg/liter againstStaphylococcus aureus(n= 11,680), coagulase-negative staphylococci (n= 1,923), streptococci (n= 4,380), andMoraxella catarrhalis(n= 145), 0.5 mg/liter againstStaphylococcus lugdunensis(n= 120) andHaemophilus influenzae(n= 352), 1 mg/liter againstEnterococcus faecalis(n= 1,241), and 2 mg/liter againstHaemophilus parainfluenzae(n= 70). The activity againstEnterococcus faeciumwas more limited (MIC90, 8 mg/liter). The spectrum and potency of AZD0914 included fluoroquinolone-resistant isolates in each species group, including methicillin-resistant staphylococci, penicillin-resistant streptococci, vancomycin-resistant enterococci, β-lactamase-producingHaemophilusspp., andM. catarrhalis. Based on thesein vitrofindings, AZD0914 warrants further investigation for its utility against a variety of Gram-positive and fastidious Gram-negative bacterial species.

scholarly journals In Vitro Activities of ME1036 (CP5609), a Novel Parenteral Carbapenem, against Methicillin-Resistant Staphylococci

2004 ◽  
Vol 48 (8) ◽  
pp. 2831-2837 ◽  
Author(s):  
Mizuyo Kurazono ◽  
Takashi Ida ◽  
Keiko Yamada ◽  
Yoko Hirai ◽  
Takahisa Maruyama ◽  
...  
Keyword(s):  
Multiple Drug ◽  
Gram Negative Bacteria ◽  
Coagulase Negative Staphylococci ◽  
Gram Positive ◽  
Gram Negative ◽  
Methicillin Resistant ◽  
Gram Positive Bacteria ◽  
Multiple Drug Resistant ◽  
Time Kill

ABSTRACT ME1036, formerly CP5609, is a novel parenteral carbapenem with a 7-acylated imidazo[5,1-b]thiazole-2-yl group directly attached to the carbapenem moiety of the C-2 position. The present study evaluated the in vitro activities of ME1036 against clinical isolates of gram-positive and gram-negative bacteria. ME1036 displayed broad activity against aerobic gram-positive and gram-negative bacteria. Unlike other marketed β-lactam antibiotics, ME1036 maintained excellent activity against multiple-drug-resistant gram-positive bacteria, such as methicillin-resistant staphylococci and penicillin-resistant Streptococcus pneumoniae (PRSP). The MICs of this compound at which 90% of isolates were inhibited were 2 μg/ml for methicillin-resistant Staphylococcus aureus (MRSA), 2 μg/ml for methicillin-resistant coagulase-negative staphylococci, and 0.031 μg/ml for PRSP. In time-kill studies with six strains of MRSA, ME1036 at four times the MIC caused a time-dependent decrease in the numbers of viable MRSA cells. The activity of ME1036 against MRSA is related to its high affinity for penicillin-binding protein 2a, for which the 50% inhibitory concentration of ME1036 was approximately 300-fold lower than that of imipenem. In conclusion, ME1036 demonstrated a broad antibacterial spectrum and high levels of activity in vitro against staphylococci, including β-lactam-resistant strains.

scholarly journals In Vitro Activity of Ceftazidime-Avibactam against Isolates from Patients in a Phase 3 Clinical Trial for Treatment of Complicated Intra-abdominal Infections

2018 ◽  
Vol 62 (7) ◽  
pp. e02584-17 ◽  
Author(s):  
Gregory G. Stone ◽  
Paul Newell ◽  
Patricia A. Bradford
Keyword(s):  
Clinical Trial ◽  
Pseudomonas Aeruginosa ◽  
Treatment Options ◽  
Multidrug Resistant ◽  
Phase 3 ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type ◽  
Abdominal Infections

ABSTRACT The increasing prevalence of multidrug-resistant Gram-negative pathogens has generated a requirement for new treatment options. Avibactam, a novel non-β-lactam–β-lactamase inhibitor, restores the activity of ceftazidime against Ambler class A, C, and some class D β-lactamase-producing strains of Enterobacteriaceae and Pseudomonas aeruginosa. The in vitro activities of ceftazidime-avibactam versus comparators were evaluated against 1,440 clinical isolates obtained in a phase 3 clinical trial in patients with complicated intra-abdominal infections (cIAI; ClinicalTrials.gov identifier NCT01499290). Overall, in vitro activities were determined for 803 Enterobacteriaceae, 70 P. aeruginosa, 304 Gram-positive aerobic, and 255 anaerobic isolates obtained from 1,066 randomized patients at baseline. Susceptibility was determined by broth microdilution. The most commonly isolated Gram-negative, Gram-positive, and anaerobic pathogens were Escherichia coli (n = 549), Streptococcus anginosus (n = 130), and Bacteroides fragilis (n = 96), respectively. Ceftazidime-avibactam was highly active against isolates of Enterobacteriaceae, with an overall MIC90 of 0.25 mg/liter. In contrast, the MIC90 for ceftazidime alone was 32 mg/liter. The MIC90 value for ceftazidime-avibactam (4 mg/liter) was one dilution lower than that of ceftazidime alone (8 mg/liter) against isolates of Pseudomonas aeruginosa. The ceftazidime-avibactam MIC90 for 109 ceftazidime-nonsusceptible Enterobacteriaceae isolates was 2 mg/liter, and the MIC range for 6 ceftazidime-nonsusceptible P. aeruginosa isolates was 8 to 32 mg/liter. The MIC90 values were within the range of susceptibility for the study drugs permitted per the protocol in the phase 3 study to provide coverage for aerobic Gram-positive and anaerobic pathogens. These findings demonstrate the in vitro activity of ceftazidime-avibactam against bacterial pathogens commonly observed in cIAI patients, including ceftazidime-nonsusceptible Enterobacteriaceae. (This study has been registered at ClinicalTrials.gov under identifier NCT01499290.)

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