Pharmacokinetics and relative bioavailability study of two cefquinome sulfate intramammary infusions in cow milk

In this study, two intramammary infusions of cefquinome sulfate were investigated for pharmacokinetics and bioavailability. Twelve lactating cows for each group were administered an effective dose of 75 mg/gland for cefquinome, with milk samples collected at various time intervals. The concentrations of cefquinome in milk at different times were determined by the UPLC-MS/MS method. Analyses of noncompartmental pharmacokinetics were conducted on the concentration of cefquinome in milk. Mean pharmacokinetic parameters of group A and group B following intramammary administration were as follows: AUClast 300558.57 ± 25052.78 ng/mL and 266551.3 ± 50654.85 ng/mL, Cmax 51786.35 ± 11948.4 ng/mL and 59763.7 ± 8403.2 ng/mL, T1/2 5.69 ± 0.62 h and 5.25 ± 1.62 h, MRT 7.43 ± 0.79 h and 4.8 ± 0.78 h, respectively. Pharmacokinetic experiments showed that the relative bioavailability of group B was 88.69% that of group A. From our findings, group B (3 g: 75 mg) shows a quicker drug elimination process than group A (8 g: 75 mg), which suggests that the withdrawal period for the new formulation may be shorter.

Variability of Beta-Lactam Broth Microdilution for Pseudomonas aeruginosa

Antimicrobial susceptibility testing for Pseudomonas aeruginosa is critical to determine suitable treatment options. Commercial susceptibility tests are typically calibrated against the reference method, broth microdilution (BMD). Imprecision of minimum inhibitory concentrations (MICs) obtained by BMD for the same isolate on repeat testing is known to exist. Factors that impact the extent of variability include concentration of the inoculum, operator effects, contents of the media, inherent strain properties, and the testing process or materials. We evaluated the variability of BMD for anti-pseudomonal beta-lactams (aztreonam, cefepime, ceftazidime, meropenem, piperacillin-tazobactam, ceftazidime-avibactam, ceftolozane-tazobactam) tested against a collection of P. aeruginosa isolates. Multiple replicate BMD tests were performed and MICs were compared to assess reproducibility, including the impact of the inoculum and operator. Overall, essential agreement (EA) was ≥ 90% for all beta-lactams tested. Absolute agreement (AA) was as low as 70% for some beta-lactams. Variability from the inoculum and operators impacted the reproducibility of MICs. Piperacillin-tazobactam exhibited the highest degree of variability with 74% AA and 94%% EA. The implications of MIC variability are extensive as the MIC is essential for multiple facets of microbiology, such as the development of new compounds and susceptibility tests, dose optimization and pharmacokinetic/pharmacodynamic (PK/PD) targets for individual patients.

Sensitivity Patterns of Bacterial Pathogens Isolated from Blood Cultures of Under-Five Children with Pneumonia and Clinical Sepsis

Treatment options for pneumonia and sepsis by antibiotics are limited due to the development of multidrug-resistant bacterial strains. This unmatched case-control study determined the antibiotic sensitivity against bacterial isolates obtained from septic and nonseptic children with pneumonia. Children of either sex aged 0–59 months with a history of cough or shortness of breath and radiologically confirmed pneumonia were enrolled in this study. Cases with clinical signs of sepsis at admission (n = 151) were compared to cases without sepsis as controls (n = 107). A total of 205 children had a performance of blood culture, with 123 children suffering from clinical sepsis. Blood cultures showed bacterial growth in 19% of the septic samples, with 8% coagulase-negative staphylococci and 2.4% Acinetobacter species. Only 1.6% of the cases were infected by Streptococcus pneumonia, Haemophilus influenzae, Salmonella typhi and Klebsiella. In contrast, children without sepsis presented positive blood cultures with growth of Salmonella typhi in 2.4% of the cases and growth of Klebsiella in 1.2%. Bacteria were sensitive to imipenem in 100% of the cases (86% for meropenem, 83% for ceftazidime and 76% for ciprofloxacin). The mortality rate was significantly higher in children with pneumonia complicated by sepsis (odds ratio (OR) = 3.02, 95% confidence interval (CI), 1.11–8.64, p < 0.027). Knowledge about specific laboratory characteristics in children with pneumonia will facilitate an early diagnosis and treatment of sepsis and reduce mortality.

Systematic review: the bioavailability of orally administered antibiotics during the initial phase of a systemic infection in non-ICU patients

Background

The systemic response to an infection might influence the pharmacokinetics of antibiotics. To evaluate the desired possibility of an earlier (< 24 h) IV-to-oral switch therapy in febrile non-ICU, hospitalized patients, a systematic review was performed to assess the effect of the initial phase of a systemic infection on the bioavailability of orally administered antibiotics in such patients.

Methods

An electronic search was conducted in MEDLINE and Embase up to July 2020. Studies were selected when outcome data were collected during the initial stage of a febrile disease. Outcome data were (maximum) serum concentrations, time of achieving maximum serum concentration, and the area-under-the-plasma-concentration-time curve or bioavailability of orally administered antibiotics. Risk of bias was assessed.

Results

We identified 9 studies on 6 antibiotics. Ciprofloxacin was the most frequently studied drug. Outcomes of the studies were heterogeneous and generally had a high risk of bias. Three small studies, two on ciprofloxacin and one on clarithromycin, compared the pharmacokinetics of febrile patients with those of clinically recovered patients and suggested that bioavailability was not altered in these patients. Other studies either compared the pharmacokinetics in febrile patients with reported pharmacokinetic values from earlier studies in healthy volunteers (n = 2), or provided no comparison at all and were non-conclusive (n = 4).

Conclusion

There is a clear knowledge gap regarding the bioavailability of orally administered antibiotics in non-ICU patients during the initial phase of a systemic infection. Well-designed studies on this topic are necessary to elucidate whether patients can benefit from the advantages of an earlier IV-to-oral switch.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-05919-w.

Best practice: antibiotic decision-making in ICUs

PURPOSE OF REVIEW

A major challenge in the ICU is optimization of antibiotic use. This review assesses current understanding of core best practices supporting and promoting astute antibiotic decision-making.

RECENT FINDINGS

Limiting exposure to the shortest effective duration is the cornerstone of antibiotic decision-making. The decision to initiate antibiotics should include assessment of risk for resistance. This requires synthesis of patient-level data and environmental factors to determine whether delayed initiation could be considered in some patients with suspected sepsis until sensitivity data is available. Until improved stratification scores and clinically meaningful cut-off values to identify MDR are available and externally validated, decisions as to which empiric antibiotic is used should rely on syndromic antibiograms and institutional guidance. Optimization of initial and maintenance doses is another enabler of enhanced outcome. Stewardship practices must be streamlined by re-assessment to minimize negative effects, such as a potential increase in duration of therapy and increased risk of collateral damage from exposure to multiple, sequential antibiotics that may ensue from de-escalation.

SUMMARY

Multiple challenges and research priorities for antibiotic optimization remain; however, the best stewardship practices should be identified and entrenched in daily practice. Reducing unnecessary exposure remains a vital strategy to limit resistance development.

Some Suggestions from PK/PD Principles to Contain Resistance in the Clinical Setting-Focus on ICU Patients and Gram-Negative Strains

The containment of the phenomenon of resistance towards antimicrobials is a priority, especially in preserving molecules acting against Gram-negative pathogens, which represent the isolates more frequently found in the fragile population of patients admitted to Intensive Care Units. Antimicrobial therapy aims to prevent resistance through several actions, which are collectively known as "antimicrobial stewardship", to be taken together, including the application of pharmacokinetic/pharmacodynamic (PK/PD) principles. PK/PD application has been shown to prevent the emergence of resistance in numerous experimental studies, although a straight translation to the clinical setting is not possible. Individualized antibiotic dosing and duration should be pursued in all patients, and even more especially when treating intensive care unit (ICU) septic patients in whom optimal exposure is both difficult to achieve and necessary. In this review, we report on the available data that support the application of PK/PD parameters to contain the development of resistance and we give some practical suggestions that can help to translate the benefit of PK/PD application to the bedside.

Pharmacologic optimization of antibiotics for Gram-negative infections

PURPOSE OF REVIEW

Antimicrobial resistance among Gram-negative organisms is a rapidly escalating global challenge. Pharmacologic dose optimization based on pharmacokinetic/pharmacodynamic principles is essential for managing Gram-negative infections. High-risk patient populations may receive nonoptimized antimicrobial dosing because pf physiologic changes in acute illness and/or medical interventions. The purpose of this review is to discuss opportunities for pharmacologic optimization of new agents and highlight patient populations that are often associated with poor drug exposure profiles.

RECENT FINDINGS

Dose optimization of the novel β-lactam-β-lactamase inhibitor combinations has been evaluated through optimizing exposure at the site of infection, evaluating target attainment of both the β-lactam and the β-lactamase-inhibitor in critically ill patients, and evaluating drug exposure to prevent the development of resistance. Plazomicin, a novel aminoglycoside, has pharmacodynamic optimization potential via therapeutic drug monitoring and nomogram-based dosing. Recent studies have evaluated the adequacy of dosing in varying degrees of renal function specifically acute kidney injury, continuous renal replacement therapy (CRRT), and augmented renal clearance (ARC).

SUMMARY

The application of fundamental pharmacokinetic/pharmacodynamic principles is required to optimize new antimicrobials in the treatment of serious Gram-negative infections. Exposure at the site of infection, pharmacokinetics in critically ill patients, and exposures to prevent resistance are all considerations to improve microbiologic and clinical outcomes. Therapeutic drug monitoring may be needed for high-risk patients.

Synergistic Combinations of Antibiotics with Cumin, Oregano and Rosewood Oils as a Strategy to Preserve the Antibiotic Repertoire

Background:

Formulations employing synergistic combinations of antibiotics with Essential Oils (EOs) could help preserve the antibiotic repertoire by improving their activity against resistant bacteria.

Objective:

Antimicrobial interactions between double and triple combinations of EOs, EO components and antibiotics were determined using the checkerboard method. The most active triple combinations were then assessed by a time-kill assay.

Methods:

Two synergistic EO-antibiotic combinations and eight additive EO-antibiotic combinations reduced the antibiotic minimum inhibitory concentration below clinical sensitivity breakpoints according to the checkerboard method. However, all the tested combinations were additive according to the time-kill assay; while the combinations completely killed S. aureus, E. coli and P. aeruginosa cells in 2 h. At least one EO compound from the combination alone completely killed the cells of test species.

Results:

Two synergistic EO-antibiotic combinations and eight additive EO-antibiotic combinations reduced the antibiotic minimum inhibitory concentration below clinical sensitivity breakpoints according to the checkerboard method. However, all the tested combinations were additive according to the time-kill assay; while the combinations completely killed S. aureus, E. coli and P. aeruginosa cells in 2 h. At least one EO compound from the combination alone completely killed the cells of test species.

Conclusion:

Positive interactions support the use of EOs or EO components to enhance antibiotic efficacy against antibiotic resistant bacteria. The EO-antibiotic combinations tested by the time kill assay were indifferent; therefore, the observed antimicrobial activity did not arise from synergistic mechanisms as indicated by the checkerboard method. Investigation of other synergistic combinations identified by the checkerboard method could reveal more promising candidates.

Evaluation of the impact of a nationwide massive online open course on the appropriate use of antimicrobials

Objectives

To evaluate the impact of a massive online open course (MOOC) design on the appropriate use of antimicrobial agents, to determine specific study areas with better learning outcomes and to identify weak points.

Methods

A pre- and post-intervention study in the context of a training course on infectious diseases aimed at health professionals. We designed a questionnaire with 30 questions related to the management of infectious diseases in different clinical situations. Participants had to answer the questions based on their competencies and training for these situations. We analysed the scores obtained before and after the course and the resulting progress. In addition, an open response section was provided to enable a qualitative evaluation.

Results

Two thousand one hundred and forty-eight health professionals were enrolled in the course. The questionnaire was completed before and after the course by 606 participants, mainly physicians (81.2%) and pharmacists (15.4%). The mean overall scores for the pre- and post-course questionnaires were 6.2 (SD 1.38) and 7.9 (SD 0.88), respectively (overall score increase = 1.8, SD 1.21, P < 0.001). A significant increase in self-assessment was detected (P < 0.001) for all the questions. Qualitative assessments were provided by 218 participants with 225 comments, most of which were very positive.

Conclusions

The course with a MOOC design showed a great teaching capacity in the infectious diseases area for all the clinical situations analysed, notably in the management of severe infections with higher mortality. For future editions of this training activity, the need to include other infectious diseases, especially infections in primary care, was highlighted.

The Role of Antibiotic Stewardship in Promoting Appropriate Antibiotic Use

Antibiotics are one of the most significant medical discoveries in human history. The widespread use of antibiotics has resulted in the emergence of antibiotic-resistant pathogens. This fact, coupled with the paucity of new antibiotic developments, has spurred efforts to combat antibiotic resistance. One of the most critical components of these efforts is antibiotic stewardship, a multidisciplinary endeavor, employing a collection of interventions in a variety of health care settings with the aim of promoting appropriate utilization of antibiotics. This article describes antibiotic stewardship programs and key practices used to minimize the development and spread of antibiotic-resistant pathogens including the optimization of antibiotic pharmacokinetics and pharmacodynamics, the application of rapid diagnostic tools, and the use of computerized provider order entry tools.

In vitro investigation of synergy among fosfomycin and parenteral antimicrobials against carbapenemase-producing Enterobacteriaceae

Intravenous fosfomycin is undergoing clinical development in the United States for treatment of complicated urinary tract infections (cUTIs) and may be prescribed as a component of dual antibiotic regimens against carbapenemase-producing Enterobacteriaceae (CPE). Fosfomycin, aztreonam, cefepime, ceftazidime, ceftazidime/avibactam, ceftolozane/tazobactam, meropenem, piperacillin/tazobactam, and tobramycin minimum inhibitory concentrations (MICs) were determined by gradient diffusion strip (GDS) against CPE isolates (N = 49). The GDS cross method was used to assess antibiotic interactions between fosfomycin and the aforementioned parenteral antibiotics. The resultant fractional inhibitory concentration index was used to classify interactions. Fosfomycin-containing combinations were evaluated only if nonsusceptible to the second agent. The fosfomycin MIC₅₀ was ≥1024 mg/L by GDS. Synergy or additivity was detected in 80 (22%) fosfomycin-containing combinations. Antagonism was not observed. Ceftolozane/tazobactam most frequently displayed synergy [8 (16.3%) isolates]. When CPE are isolated, clinical laboratories should consider performing GDS synergy tests to identify favorable antibiotic interactions.

Bacterial Resistance in Pneumonia in Developing Countries-A Role for Iron Chelation

Pneumonia represents one of the major infectious diseases in developing countries and is associated with high mortality, in particular in children under the age of five. The main causative bacterial agents are Streptococcus pneumoniae and Haemophilus influenzae type B, accounting for 33% and 16%, respectively, of the mortality in under-fives. Iron modulates the immune response in infectious diseases and increased iron levels can lead to complications such as sepsis and multiorgan failure. This review will look into the use of iron chelators in order to reduce microbial growth and attenuate a dysregulated immune response during infection. Our hypothesis is that temporary restriction of iron will lessen the incidence and complication rate of infections like pneumonia and result in a decrease of mortality and morbidity.

Quantitative and synthetic biology approaches to combat bacterial pathogens

Antibiotic resistance is one of the biggest threats to public health. The rapid emergence of resistant bacterial pathogens endangers the efficacy of current antibiotics and has led to increasing mortality and economic burden. This crisis calls for more rapid and accurate diagnosis to detect and identify pathogens, as well as to characterize their response to antibiotics. Building on this foundation, treatment options also need to be improved to use current antibiotics more effectively and develop alternative strategies that complement the use of antibiotics. We here review recent developments in diagnosis and treatment of bacterial pathogens with a focus on quantitative biology and synthetic biology approaches.

Impact of clinical pharmacist intervention on antimicrobial use in a small 164-bed hospital

Objectives

To study the impact of clinical pharmacist interventions (PIs) on antimicrobial prescriptions in terms of physician acceptance rates, clinical benefits and antimicrobial use/cost outcomes.

Methods

This study retrospectively analysed the impact of antimicrobial PIs over a 2-year period (October 2012 to October 2014) in a private non-teaching 164-bed hospital without a formal antimicrobial stewardship programme. Excluded from the study were outpatients and patients admitted to the intensive care unit or the emergency department. The PIs focused on appropriate indication and appropriate dosage; drug adverse events, allergies, intolerance and interactions; sequential therapy; therapeutic de-escalation; excessive duration of treatment and therapeutic drug monitoring. Carbapenems and linezolid were classified as special-vigilance drugs. Amoxicillin-clavulanic, piperacillin-tazobactam and vancomycin were classified as preferred drugs. Clinical benefits evaluated in accordance with internal guidelines, were classified as enhancing appropriate antimicrobial prescription or potentially reducing toxicity. Antimicrobial use and expenditure were compared with that of the previous 2-year period.

Results

386 PIs were implemented in 303 patients. The overall acceptance rate was 83.4%. The acceptance rate for appropriate prescription PIs was significantly lower than for toxicity PIs (73.7% vs 90.9%; p<0.0001). Significant reductions in the use of special-vigilance drugs (from 39.9 (22.2-86.0) to 28.0 (6.0-43.4) defined daily doses (DDD)/1000 patient-days; p=0.0003) were seen and increases in the use of piperacillin-tazobactam (from 13.2 (0-22.9) to 17.2 (6.9-44.8) DDD/1000 patient-days; p=0.007) and of cephalosporins (from 123.5 (61.8-196.6) to 149.1 (80.3-228.2) DDD/1000 patient-days; p=0.027). Overall cost savings were 5.1%.

Conclusions

PIs on antimicrobial prescriptions may be effective in enhancing appropriate use of antimicrobials, reducing their toxicity, reducing the use of special-vigilance drugs and reducing overall antimicrobial cost.

Management of KPC-producing Klebsiella pneumoniae infections

BACKGROUND

Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae (KPC-KP) has become one of the most important contemporary pathogens, especially in endemic areas.

AIMS

To provide practical suggestion for physicians dealing with the management of KPC-KP infections in critically ill patients, based on expert opinions.

SOURCES

PubMed search for relevant publications related to the management of KPC-KP infections.

CONTENTS

A panel of experts developed a list of 12 questions to be addressed. In view of the current lack of high-level evidence, they were asked to provide answers on the bases of their knowledge and experience in the field. The panel identified several key aspects to be addressed when dealing with KPC-KP in critically ill patients (preventing colonization in the patient, preventing infection in the colonized patient and colonization of his or her contacts, reducing mortality in the infected patient by rapidly diagnosing the causative agent and promptly adopting the best therapeutic strategy) and provided related suggestions that were based on the available observational literature and the experience of panel members.

IMPLICATIONS

Diagnostic technologies could speed up the diagnosis of KPC-KP infections. Combination treatment should be preferred to monotherapy in cases of severe infections. For non-critically ill patients without severe infections, results from randomized clinical trials are needed for ultimately weighing benefits and costs of using combinations rather than monotherapy. Multifaceted infection control interventions are needed to decrease the rates of colonization and cross-transmission of KPC-KP.

Potency of parenteral antimicrobials including ceftolozane/tazobactam against nosocomial respiratory tract pathogens: considerations for empiric and directed therapy

BACKGROUND

Empiric therapy decisions are predicated on knowledge of both the epidemiology and antimicrobial susceptibility of the probable infecting pathogen(s). The objective of this study was to evaluate the microbial distribution and phenotypic profiles of nosocomial respiratory isolates collected from multiple US hospitals and assess the clinical utility of various monotherapy and combination regimens.

METHODS

Hospitals provided consecutive non-duplicate adult inpatients Gram-negative nosocomial respiratory isolates from cultures received ≥48 h after hospital admission. Minimum inhibitory concentrations (MICs) for 12 antimicrobials were determined using broth microdilution methods. An antibiogram was constructed for monotherapy regimens as well as combinations inclusive of either tobramycin (TOB) or ciprofloxacin (CIP).

RESULTS

Six hospitals provided 518 nosocomial respiratory isolates. P. aeruginosa (PSA) comprised 28% of the population followed by Klebsiella pneumoniae (13%), Enterobacter spp. (13%), S. maltophilia (9%), S. marcesens (6%), A. baumannii (6%), and others (18%). When considering monotherapy for the Enterobacteriaceae & PSA ceftolozane/tazobactam (C/T) provided the highest (87%) percent susceptibility (%S) followed by meropenem (MEM), CIP, cefepime (FEP), ceftazidime (CAZ) and piperacillin-tazobactam (TZP) at 71-85%S. The addition of TOB > CIP improved the probability that the antimicrobial combination would provide ≥1 active agent.

CONCLUSIONS

PSA was the predominant nosocomial respiratory pathogen; however, the Enterobacteriaceae comprised an additional 53% in this survey. When considering empiric β-lactam monotherapy therapy for the entire spectrum of pathogens C/T provided the highest (78%) %S followed by MEM, FEP and TZP. The addition of either TOB > CIP to these β-lactams enhances the likelihood that an active agent would be selected when considering empirical therapy choices for nosocomial respiratory tract infections.

Comparative analysis of the cost and effectiveness of generic and brand-name antibiotics: the case of uncomplicated urinary tract infection

PURPOSE

Generic medications used for chronic diseases are beneficial in containing healthcare costs and improving drug accessibility. However, the effects of generic drugs in acute and severe illness remain controversial. This study aims to investigate treatment costs and outcomes of generic antibiotics prescribed for adults with a urinary tract infection in outpatient settings.

METHODS

The data source was the Longitudinal Health Insurance Database of Taiwan. We included outpatients aged 20 years and above with a urinary tract infection who required one oral antibiotic for which brand-name and generic products were simultaneously available. Drug cost and overall healthcare expense of the index consultation, healthcare cost during a 42-day follow-up period, and treatment failure rates were the main dependent variables. Data were compared between brand-name and generic users from the entire cohort and a propensity score-matched samples.

RESULTS

Results from the entire cohort and propensity score-matched samples were similar. Daily antibiotic cost was significantly lower among generic users than brand-name users. Significant lower total drug claims of the index consultation only existed in patients receiving the investigated antibiotics, while the drug price between brand-name and generic versions were relatively large (e.g., >50%). The overall healthcare cost of the index consultation, healthcare expenditure during a 42-day follow-up period, and treatment failure rates were similar between the two groups.

CONCLUSIONS

Compared with those treated with brand-name antibiotics, outpatients who received generic antibiotics had equivalent treatment outcomes with lower drug costs. Generic antibiotics are effective and worthy of adoption among outpatients with simple infections indicating oral antibiotic treatment. Copyright © 2016 John Wiley & Sons, Ltd.

Tracking Cefoperazone/Sulbactam Resistance Development In vivo in A. baumannii Isolated from a Patient with Hospital-Acquired Pneumonia by Whole-Genome Sequencing

Cefoperazone/sulbactam has been shown to be efficacious for the treatment of infections caused by Acinetobacter baumannii; however, the mechanism underlying resistance to this synergistic combination is not well understood. In the present study, two A. baumannii isolates, AB1845 and AB2092, were isolated from a patient with hospital-acquired pneumonia before and after 20 days of cefoperazone/sulbactam therapy (2:1, 3 g every 8 h with a 1-h infusion). The minimum inhibitory concentration (MIC) of cefoperazone/sulbactam for AB1845 and AB2092 was 16/8 and 128/64 mg/L, respectively. Blood samples were collected on day 4 of the treatment to determine the concentration of cefoperazone and sulbactam. The pharmacokinetic/pharmacodynamic (PK/PD) indices (%T_>MIC) were calculated to evaluate the dosage regimen and resistance development. The results showed that %T_>MIC of cefoperazone and sulbactam was 100% and 34.5% for AB1845, and 0% and 0% for AB2092, respectively. Although there was no available PK/PD target for sulbactam, it was proposed that sulbactam should be administered at higher doses or for prolonged infusion times to achieve better efficacy. To investigate the mechanism of A. baumannii resistance to the cefoperazone/sulbactam combination in vivo, whole-genome sequencing of these two isolates was further performed. The sequencing results showed that 97.6% of the genome sequences were identical and 33 non-synonymous mutations were detected between AB1845 and AB2092. The only difference of these two isolates was showed in sequencing coverage comparison. There was a 6-kb amplified DNA fragment which was three times higher in AB2092, compared with AB1845. The amplified DNA fragment containing the bla_OXA-23 gene on transposon Tn2009. Further quantitative real-time PCR results demonstrated that gene expression at the mRNA level of bla_OXA-23 was >5 times higher in AB2092 than in AB1845. These results suggested that the bla_OXA-23 gene had higher expression level in AB2092 via gene amplification and following transcription. Because gene amplification plays a critical role in antibiotic resistance in many bacteria, it is very likely that the bla_OXA-23 amplification results in the development of cefoperazone/sulbactam resistance in vivo.