In vitro antimicrobial activity of cefoperazone-sulbactam combinations against 554 clinical isolates including a review and beta-lactamase studies

Novel Siderophore Cephalosporin and Combinations of Cephalosporins with β-Lactamase Inhibitors as an Advancement in Treatment of Ventilator-Associated Pneumonia

In an era of increasing antibiotic resistance among pathogens, the treatment options for infectious diseases are diminishing. One of the clinical groups especially vulnerable to this threat are patients who are hospitalized in intensive care units due to ventilator-associated pneumonia caused by multidrug-resistant/extensively drug-resistant Gram-negative bacteria. In order to prevent the exhaustion of therapeutic options for this life-threatening condition, there is an urgent need for new pharmaceuticals. Novel β-lactam antibiotics, including combinations of cephalosporins with β-lactamase inhibitors, are proposed as a solution to this escalating problem. The unique mechanism of action, distinctive to this new group of siderophore cephalosporins, can overcome multidrug resistance, which is raising high expectations. In this review, we present the summarized results of clinical trials, in vitro studies, and case studies on the therapeutic efficacy of cefoperazone-sulbactam, ceftolozane-tazobactam, ceftazidime-avibactam, and cefiderocol in the treatment of ventilator-associated pneumonia. We demonstrate that treatment strategies based on siderophore cephalosporins and combinations of β-lactams with β-lactamases inhibitors show comparable or higher clinical efficacy than those used with classic pharmaceuticals, like carbapenems, colistin, or tigecycline, and are often associated with a lower risk of adverse events.

Current Therapeutic Approaches for Multidrug-Resistant and Extensively Drug-Resistant Acinetobacter baumannii Infections

The treatment of Acinetobacter baumannii infections remains a challenge for physicians worldwide in the 21st century. The bacterium possesses a multitude of mechanisms to escape the human immune system. The consequences of A. baumannii infections on morbidity and mortality, as well on financial resources, remain dire. Furthermore, A. baumannii superinfections have also occurred during the COVID-19 pandemic. While prevention is important, the antibiotic armamentarium remains the most essential factor for the treatment of these infections. The main problem is the notorious resistance profile (including resistance to carbapenems and colistin) that this bacterium exhibits. While newer beta lactam/beta-lactamase inhibitors have entered clinical practice, with excellent results against various infections due to Enterobacteriaceae, their contribution against A. baumannii infections is almost absent. Hence, we have to resort to at least one of the following, sulbactam, polymyxins E or B, tigecycline or aminoglycosides, against multidrug-resistant (MDR) and extensively drug-resistant (XDR) A. baumannii infections. Furthermore, the notable addition of cefiderocol in the fight against A. baumannii infections represents a useful addition. We present herein the existing information from the last decade regarding therapeutic advances against MDR/XDR A. baumannii infections.

Heterogeneity in M. tuberculosis β-lactamase inhibition by Sulbactam

For decades, researchers have elucidated essential enzymatic functions on the atomic length scale by tracing atomic positions in real-time. Our work builds on possibilities unleashed by mix-and-inject serial crystallography (MISC) at X-ray free electron laser facilities. In this approach, enzymatic reactions are triggered by mixing substrate or ligand solutions with enzyme microcrystals. Here, we report in atomic detail (between 2.2 and 2.7 Å resolution) by room-temperature, time-resolved crystallography with millisecond time-resolution (with timepoints between 3 ms and 700 ms) how the Mycobacterium tuberculosis enzyme BlaC is inhibited by sulbactam (SUB). Our results reveal ligand binding heterogeneity, ligand gating, cooperativity, induced fit, and conformational selection all from the same set of MISC data, detailing how SUB approaches the catalytic clefts and binds to the enzyme noncovalently before reacting to a trans-enamine. This was made possible in part by the application of singular value decomposition to the MISC data using a program that remains functional even if unit cell parameters change up to 3 Å during the reaction.

Durlobactam, a Broad-Spectrum Serine β-lactamase Inhibitor, Restores Sulbactam Activity Against Acinetobacter Species

Sulbactam-durlobactam is a pathogen-targeted β-lactam/β-lactamase inhibitor combination in late-stage development for the treatment of Acinetobacter infections, including those caused by multidrug-resistant strains. Durlobactam is a member of the diazabicyclooctane class of β-lactamase inhibitors with broad-spectrum serine β-lactamase activity. Sulbactam is a first-generation, narrow-spectrum β-lactamase inhibitor that also has intrinsic antibacterial activity against Acinetobacter spp. due to its ability to inhibit penicillin-binding proteins 1 and 3. The clinical utility of sulbactam for the treatment of contemporary Acinetobacter infections has been eroded over the last decades due to its susceptibility to cleavage by numerous β-lactamases present in this species. However, when combined with durlobactam, the activity of sulbactam is restored against this problematic pathogen. The following summary describes what is known about the molecular drivers of activity and resistance as well as results from surveillance and in vivo efficacy studies for this novel combination.

Heterogeneity in the M. tuberculosis β-Lactamase Inhibition by Sulbactam

For decades, researchers have been determined to elucidate essential enzymatic functions on the atomic lengths scale by tracing atomic positions in real time. Our work builds on new possibilities unleashed by mix-and-inject serial crystallography (MISC) 1-5 at X-ray free electron laser facilities. In this approach, enzymatic reactions are triggered by mixing substrate or ligand solutions with enzyme microcrystals 6 . Here, we report in atomic detail and with millisecond time-resolution how the Mycobacterium tuberculosis enzyme BlaC is inhibited by sulbactam (SUB). Our results reveal ligand binding heterogeneity, ligand gating 7-9 , cooperativity, induced fit 10,11 and conformational selection 11-13 all from the same set of MISC data, detailing how SUB approaches the catalytic clefts and binds to the enzyme non-covalently before reacting to a trans- enamine. This was made possible in part by the application of the singular value decomposition 14 to the MISC data using a newly developed program that remains functional even if unit cell parameters change during the reaction.

Cefoperazone/sulbactam: New composites against multiresistant gram negative bacteria?

Sulbactam, a class A β-lactamase inhibitor, added to cefoperazone either at a fixed 8 mg/L level of sulbactam or at a level of fixed cefoperazone: sulbactam ratio (2:1) would constitute a combination form of cefoperazone/sulbactam, which has better activities against Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii than cefoperazone alone. Cefoperazone/sulbactam (1:1 or 1:2) has greater in-vitro activity against most multidrug-resistant organisms (ESBL- and AmpC-producing Enterobacteriaceae and carbapenem-resistant A. baumannii except for carbapenem-resistant P. aeruginosa) than a 2:1 ratio. However, increased sulbactam concentration may induce AmpC production. Besides, sulbactam concentration might not be readily achievable in serum if the susceptibility rates were defined by the breakpoints of higher sulbactam composites, such as ≤16/16 (1:1) or 16/32 (1:2) mg/L. Carbapenemases (KPC-, OXA-type enzymes and metallo-β-lactamases) can't be inhibited by sulbactam. Some in-vitro studies showed that increasing sulbactam composites of cefoperazone/sulbactam had no effect on carbapenem-resistant P. aeruginosa, suggesting the presence of carbapenemases or AmpC overproduction that could not be overcome by increasing sulbactam levels to recover cefoperazone activity. Sulbactam alone has good intrinsic activity against carbapenem-resistant Acinetobacter strains sometimes even in the presence of carbapenemase genes, suggesting unsteady levels of carbapenemases. In conclusion, appropriate composites of cefoperazone and β-lactamase inhibitor sulbactam may expand the clinical use if the pharmacokinetic optimization could be achieved in the human serum.

Dietary Xanthan Gum Alters Antibiotic Efficacy against the Murine Gut Microbiota and Attenuates Clostridioides difficile Colonization

Dietary fiber provides a variety of microbiota-mediated benefits ranging from anti-inflammatory metabolites to pathogen colonization resistance. A healthy gut microbiota protects against Clostridioides difficile colonization. Manipulation of these microbes through diet may increase colonization resistance to improve clinical outcomes. The primary objective of this study was to identify how the dietary fiber xanthan gum affects the microbiota and C. difficile colonization. We added 5% xanthan gum to the diet of C57BL/6 mice and examined its effect on the microbiota through 16S rRNA gene amplicon sequencing and short-chain fatty acid analysis. Following either cefoperazone or an antibiotic cocktail administration, we challenged mice with C. difficile and measured colonization by monitoring the CFU. Xanthan gum administration is associated with increases in fiber-degrading taxa and short-chain fatty acid concentrations. However, by maintaining both the diversity and absolute abundance of the microbiota during antibiotic treatment, the protective effects of xanthan gum administration on the microbiota were more prominent than the enrichment of these fiber-degrading taxa. As a result, mice that were on the xanthan gum diet experienced limited to no C. difficile colonization. Xanthan gum administration alters mouse susceptibility to C. difficile colonization by maintaining the microbiota during antibiotic treatment. While antibiotic-xanthan gum interactions are not well understood, xanthan gum has previously been used to bind drugs and alter their pharmacokinetics. Thus, xanthan gum may alter the activity of the oral antibiotics used to make the microbiota susceptible. Future research should further characterize how this and other common dietary fibers interact with drugs.IMPORTANCE A healthy gut bacterial community benefits the host by breaking down dietary nutrients and protecting against pathogens. Clostridioides difficile capitalizes on the absence of this community to cause diarrhea and inflammation. Thus, a major clinical goal is to find ways to increase resistance to C. difficile colonization by either supplementing with bacteria that promote resistance or a diet to enrich for those already present in the gut. In this study, we describe an interaction between xanthan gum, a human dietary additive, and the microbiota resulting in an altered gut environment that is protective against C. difficile colonization.

Safety and Efficacy of Cefoperazone Plus Sulbactam versus Ceftazidime in the Empiric Treatment of Febrile Neutropenia

Objective:

To compare the safety and efficacy of cefoperazone plus sulbactam (CPZ + SB) (3 g [2:1] every 8 h) and ceftazidime (CTZ) (2 g every 8 h) as monotherapy in the empiric treatment of febrile neutropenia in patients with cancer.

Patients:

One hundred eighteen cancer patients with chemotherapy-associated neutropenia and fever. Most patients (82) received norfloxacin and fluconazole as prophylaxis.

Results:

Fifty-nine patients were enrolled in the CPZ + SB group, and 59 were enrolled in the CTZ group. The mean duration of antibiotic therapy was less than 10 days in both groups. Forty-three patients (19 in the CPZ + SB group and 24 in the CTZ group) were bacteremic, and 7 others had cellulitis. Of the 56 microorganisms producing bacteremia, 51 were gram-positive bacteria, mostly staphylococci (28 isolates) and streptococci (22 isolates). Gram-positive cocci were more frequently resistant to CTZ than to CPZ + SB (77% vs. 40%, respectively; p < 0.002). However, the clinical response rate at 72 hours of therapy was 53% in the CPZ + SB group and 52% in the CTZ group (p = 1.0). At the end of therapy, clinical responses were similar in the two groups (p = 0.19). Clinical success with antibiotic modification was seen in 42% of the CPZ + SB recipients and in 58% of CTZ recipients (p = 0.10). Bacteriologic eradication among bacteremic patients appeared to be slightly better in the CPZ + SB group (79% vs. 54%; p = 0.09). Except for rashes in 3 patients (1 in the CPZ + SB group and 2 in the CTZ group), both drugs were well tolerated. Adverse events included superinfections, transient elevation of serum transaminase concentrations, diarrhea, and chills.

Conclusions:

CPZ + SB was superior to CTZ in its in vitro activity against aerobic gram-positive cocci encountered in the study; however, the clinical efficacy and safety of the two drug treatments were similar in the empiric therapy for febrile neutropenia.

Comparison of efficacy of cefoperazone/sulbactam and imipenem/cilastatin for treatment of Acinetobacter bacteremia

Multiple antibiotic resistance threatens successful treatment of Acinetobacter baumannii infections worldwide. Increasing interest in the well-known activity of sulbactam against the genus Acinetobacter has been aroused. The purpose of this study was to compare the outcomes for patients with Acinetobacter bacteremia treated with cefoperazone/sulbactam versus imipenem/cilastatin. Forty-seven patients with Acinetobacter baumannii bacteremia were analyzed through a retrospective review of their medical records for antibiotic therapy and clinical outcome. Thirty-five patients were treated with cefoperazone/sulbactam, and twelve patients with imipenem/cilastatin. The percentage of favorable response after 72 hours was not statistically different between cefoperazone/sulbactam group and imipenem/cilastatin group. The mortality rate was not statistically different, too. Cefoperazone/sulbactam was found to be as useful as imipenem/cilastatin for treating patients with Acinetobacter bacteremia.

In vitro activities of beta-lactam antibiotics alone and in combination with sulbactam against Gram-negative bacteria

The resistance rates of ampicillin/sulbactam 2:1 against imipenem-susceptible and -resistant Acinetobacter baumannii were 23.5 and 30%, respectively. Ceftazidime/sulbactam combination showed significant reduction of resistant rates against Enterobacter cloacae, A. baumannii, ESBL Klebsiella pneumoniae. MIC90 of cefoperazone against E. cloacae, Serratia marcescens, A. baumannii and ESBL K. pneumoniae were > 128 mg/l. Addition of sulbactam enhanced the antimicrobial activities significantly. When imipenem was combined with sulbactam, the resistant rates against imipenem-resistant A. baumanni were significantly reduced. Cefepime/sulbactam combination was active against imipenem-resistant A. baumanni. The resistance rates of aztreonam/sulbactam combination against E. cloacae, imipenem-sensitive and resistant A. baumannii, ESBL K. pneumoniae were lowered significantly. The cefotaxime/sulbactam combination showed a significant improvement of activities against E. cloacae, S. marcescens, A. baumannii and ESBL K. pneumoniae.

Multiresistant Acinetobacter infections: a role for sulbactam combinations in overcoming an emerging worldwide problem

Recent studies have highlighted the emergence of infections involving multiresistant Acinetobacter clinical isolates. Sulbactam offers direct antimicrobial activity against Acinetobacter species. Accordingly, co-administration of sulbactam with ampicillin or cefoperazone offers the potential of effective empirical therapy against Acinetobacter and other bacteria such as Enterobacteriaceae in institutions in which they are susceptible. Many in vitro studies have indicated that Acinetobacter remains fully susceptible to ampicillin-sulbactam or cefoperazone-sulbactam. Furthermore, ampicillin-sulbactam has proven clinically effective and well tolerated in the treatment of severe acinetobacter infections, including bacteremia. Therefore, ampicillin-sulbactam is a sensible option for the treatment of life-threatening acinetobacter infections.

Therapy with cefoperazone plus sulbactam against disseminated infection due to cefoperazone-resistant Pseudomonas aeruginosa and Escherichia coli in granulocytopenic mice

Using a granulocytopenic murine model, we evaluated the efficacy of cefoperazone plus sulbactam against disseminated infection due to isolates of beta-lactamase-producing, cefoperazone-resistant (MIC, > or = 50 micrograms/ml) Escherichia coli and Pseudomonas aeruginosa. Both isolates were susceptible in vitro to cefoperazone plus sulbactam (MIC, < or = 6.3 micrograms/ml). Mice rendered granulocytopenic with cyclophosphamide were divided into three groups: group A--infected, untreated mice (controls); group B--infected, cefoperazone-treated mice (700 mg/kg of body weight); and group C--infected, cefoperazone-plus-sulbactam-treated mice (700 mg plus 350 mg). In the E. coli experiment, survival rates in groups A, B, and C were 25, 46, and 73%, respectively. In the experiment with P. aeruginosa, survival rates in groups A, B, and C were 0, 10, and 50%, respectively (P < 0.001). Highly significant differences also were noted for colony counts in the blood, liver, and spleen of group C mice versus group A or B mice in both experiments. Thus, cefoperazone plus sulbactam appears to be a promising combination for the treatment of infections due to certain cefoperazone-resistant gram-negative bacilli, including P. aeruginosa.

Antibacterial activity of cefoperazone and cefoperazone plus sulbactam in a neutropenic site model

Efficacy of cefoperazone versus cefoperazone plus sulbactam was studied in a rabbit neutropenic site infection model against a broad range of clinical isolates including six isolates each of staphylococci, enterococci, pneumococci, Enterobacteriaceae, and Pseudomonas aeruginosa. Therapy of cefoperazone plus sulbactam demonstrated enhanced efficacy against the staphylococci, pseudomonads, and Enterobacteriaceae. The activity of cefoperazone against enterococci and pneumococci was not enhanced or inhibited by the addition of sulbactam. Increased concentrations of cefoperazone found at the infection sites when sulbactam was added to the therapeutic regimen indicates that sulbactam provided a protection to cefoperazone from beta-lactamases produced by staphylococci and Enterobacteriaceae. The combination improved the efficacy of cefoperazone in this animal model.

In-vitro susceptibility of cefoperazone-susceptible and -resistant gram-negative rods to cefoperazone plus sulbactam, other beta-lactams, aminoglycosides and quinolone

We compared the in-vitro activity of cefoperazone-sulbactam (2:1), other beta-lactams, amino-glycosides and ciprofloxacin against cefoperazone-susceptible and -resistant nosocomial gram-negative bacilli. Resistant isolates including Pseudomonas aeruginosa were susceptible to cefoperazone-sulbactam; the susceptible isolates had modestly increased susceptibility to the combination. Sulbactam, by itself, was poorly active. Among others tested, ciprofloxacin and imipenem were the most active. No inoculum effect was seen with cefoperazone-sulbactam and this drug combination had a prolonged post-antibiotic effect. Cefoperazone-sulbactam is an attractive candidate for evaluation in the treatment of nosocomial infections due to aerobic gram-negative bacilli.

In vitro comparison of cefoperazone/sulbactam with selected antimicrobials against 300 bacteroides isolates. Inhibitory activity and time-kill kinetic studies

The susceptibilities of 258 Bacteroides fragilis group isolates and 42 other Bacteroides species isolates against cefoperazone, cefoperazone/sulbactam (2:1 ratio) and selected other antimicrobials were determined by broth microdilution method. All isolates were susceptible to cefoperazone/sulbactam, ampicillin/sulbactam, ticarcillin/clavulanate, metronidazole, and imipenem. Other antibiotics showed variables levels of resistance (5-30%). Killing curves with the cef/sulb against selected B. fragilis group isolates were performed and showed excellent bactericidal activity at two to four times the minimum inhibitory concentration (MIC) after 12 hr incubation, even against the isolates with high cefoperazone MICs (greater than or equal to 64 micrograms ml). There was no regrowth at 24 hr. Cefoperazone/sulbactam is a compound with excellent inhibitory and bactericidal activity against B. fragilis group isolates.

In vitro assessment of sulbactam plus cefoperazone in the treatment of bacteria isolated from cancer patients

Cefoperazone is a broad-spectrum cephalosporin that has been used extensively to treat infections in cancer patients. A recent survey demonstrated only a 6% resistance to this drug among Gram-negative bacteria. The combination of cefoperazone plus sulbactam was studied in vitro against consecutive isolates causing bacteremia in cancer patients as well as those selected for resistance to cefoperazone. Both a fixed ratio of sulbactam/cefoperazone (2:1 w/w) and selected concentrations of sulbactam (2, 4, 8, and 16 micrograms/ml) were studied. Sulbactam was shown to increase the susceptibility of various unselected Gram-negative bacilli; this effect increased with larger concentrations of sulbactam. The addition of sulbactam at optimum concentration levels made 29 of 65 cefoperazone-resistant Gram-negative bacilli susceptible. This effect was seen most markedly for Acinetobacter spp.

Criteria for disk susceptibility tests and quality control guidelines for the cefoperazone-sulbactam combination

For in vitro susceptibility tests with cefoperazone and sulbactam (a beta-lactamase inhibitor), 75/30-micrograms disks may be used with the interpretive zone size breakpoints that are currently used for 75-micrograms cefoperazone disks. For dilution tests, a 2:1 ratio of cefoperazone to sulbactam is recommended. For quality control purposes, MIC limits that are used to monitor cefoperazone tests were also applied to tests with the combination of drugs. For gram-negative control strains, zone size limits were calculated to be 1 mm smaller than those used for cefoperazone disks. To monitor the sulbactam portion of the combination, Acinetobacter calcoaceticus subsp. anitratus ATCC 43498 was selected; zones with 75/30-micrograms disks were 26 to 32 mm in diameter, and broth microdilution MICs ranged from 1.0/0.5 to 8.0/4.0 micrograms/ml. With cefoperazone alone, MICs for Acinetobacter calcoaceticus subsp. anitratus were 16 to 64 micrograms/ml and zones ranged from 14 to 18 mm in diameter. For anaerobic dilution tests, only Bacteroides thetaiotaomicron ATCC 29741 is recommended for cefoperazone-sulbactam; MICs ranged from 8.0/4.0 to 32/16 micrograms/ml.

Pharmacokinetics and pharmacodynamics of cefoperazone-sulbactam in patients on continuous ambulatory peritoneal dialysis

This study was conducted to determine the pharmacokinetics of the fixed combination antibiotic cefoperazone-sulbactam in patients receiving continuous ambulatory peritoneal dialysis (CAPD). In addition, the pharmacodynamic profile of this combination was determined by the use of mean bactericidal titers against selected bacterial strains. Six noninfected CAPD patients were given a fixed dose of cefoperazone (2 g) and sulbactam (1 g) either intravenously or intraperitoneally over 10 min in a randomized, two-way crossover fashion. The mean peak cefoperazone concentration in serum after intravenous administration was 280.9 micrograms/ml. The mean peak concentration in serum after intraperitoneal cefoperazone administration was 38.9 micrograms/ml and occurred 2 to 4 h postdose. The mean peak sulbactam concentration in serum after intravenous administration was 82.2 micrograms/ml. The mean peak concentration in serum after intraperitoneal sulbactam administration was 24.4 micrograms/ml and occurred at 6 h. The absolute bioavailability of the intraperitoneal dose was 61% for cefoperazone and 70% for sulbactam. Cefoperazone total body and renal clearances were unaffected by renal failure and dialysis. However, both clearance values for sulbactam were reduced markedly. Only intraperitoneal dosing provided peak inhibitory and bactericidal titers in dialysate for all organisms tested. Intravenous dosing provided satisfactory dialysate titers only for very susceptible bacterial strains. End-stage renal disease and CAPD do not alter cefoperazone pharmacokinetics; however, sulbactam dosing may need to be adjusted.

Effect of beta-lactamase inhibitors on the antimicrobial activity of cefoperazone, cefotaxime, and ceftizoxime against aerobic and anaerobic beta-lactamase producing bacteria

Clavulanic acid (2.0 micrograms/ml) lowered the minimal inhibitory concentrations (MICs) of ceftizoxime and cefotaxime against 49 strains of the Bacteroides fragilis group by a mean of 4.0 and 3.4 log2 concentrations, respectively. Sulbactam plus ceftizoxime gave almost identical results. Sulbactam lowered cefoperazone MICs by a mean of 2 log2 concentrations. Against 52 aerobic and facultative isolates producing a variety of beta-lactamase types, the use of beta-lactamase inhibitors (sulbactam) was most effective in reducing the MICs of cefoperazone.

In vitro antimicrobial spectrum, occurrence of synergy, and recommendations for dilution susceptibility testing concentrations of the cefoperazone-sulbactam combination

Broth microdilution tests and an antimicrobial interaction (synergy) studies using various combinations of cefoperazone and sulbactam were performed in an effort to determine the most appropriate in vitro dilution test system. The test results with cefoperazone and sulbactam were categorized as synergistic (complete or partial) for nearly 80% of the strains isolated from clinical trial patients. The results indicate that the cefoperazone-sulbactam fixed ratio (2:1) maximized the cefoperazone spectrum of activity and best approximated the parenteral formulation of the drug. The cefoperazone-sulbactam combination had a greater antimicrobial activity than did the other comparison beta-lactams, except for imipenem, tested against strains of the family Enterobacteriaceae. To be consistent with the National Committee for Clinical Laboratory Standards interpretive breakpoints for cefoperazone alone, the following MIC breakpoints should be applied to the combination (2:1 ratio): less than or equal to 16/8 micrograms/ml, susceptible; 32/16 micrograms/ml, moderately susceptible; and greater than or equal to 64/32 micrograms/ml, resistant.