Successful Treatment of Persistent Burkholderia cepacia Complex Bacteremia with Ceftazidime-Avibactam

First case of New Delhi metallo β-lactamase-1 (NDM-1)-producing Burkholderia cepacia complex in Iran

The Burkholderia cepacia complex (Bcc) is a gram-negative bacillus, which is intrinsically resistant to several used antibiotics, and is now recognized as a group of opportunistic pathogens in Cystic Fibrosis patients. Here, for the first time, we report the case of a patient with New Delhi metallo β-lactamase (NDM)-positive Bcc lower respiratory tract infection in Iran. The patient was a 57-year-old male admitted to our hospital due to breathlessness, with a history of pulmonary thromboembolism and hypertension. On day 14, the patient underwent bronchoscopy and a bronchoalveolar lavage (BAL) specimen was taken. BAL culture grew Bcc. The drug resistance analysis showed positive NDM resistance, with susceptibility to only quinolones, therefore, levofloxacin was prescribed to the patient. He was discharged from the hospital on the 20th day, 4 days after the initiation of levofloxacin therapy, and died at home on the fifth day after discharge. This is the first report of a lung infection caused by an extensively drug-resistant NDM-positive Bcc strain in Iran.

Species distribution and antimicrobial susceptibility of Burkholderia cepacia complex isolates in clinical infections: Experience from a tertiary care hospital, Southern India

PURPOSE

Burkholderia cepacia complex (Bcc) is a diverse group of environmental bacteria associated with opportunistic infections. The identification of Bcc using conventional methods poses challenges. Bcc infections are difficult to treat due to intrinsic antibiotic resistance. The study aimed to investigate the species distribution and antimicrobial susceptibility of clinical Bcc isolates.

METHODS

A total of 153 Bcc isolates obtained from clinical samples were analysed. Species identification was carried out using automated methods, including MALDI-TOF MS and VITEK2. Antimicrobial susceptibility testing was performed using the disc diffusion method.

RESULTS

Burkholderia cenocepacia (70.5%) emerged as the most prevalent species, followed by Burkholderia contaminans (9.8%) and Burkholderia cepacia (7.2%). Ventilator-associated pneumonia (38.6%) was the most common infection, followed by sepsis (28.1%). Co-existence of Bcc with other pathogens in many cases suggested potential co-infection scenarios. Antimicrobial susceptibility revealed that ceftazidime, co-trimoxazole and meropenem were the most effective drugs, while levofloxacin proved to be the least effective. Moderate susceptibility was noted to minocycline, with 4.6% of isolates exhibiting multi-drug resistance.

CONCLUSION

This study provides valuable insights into the prevalence, clinical associations, and antibiotic susceptibility of Bcc in India. It highlights the importance of Bcc as a nosocomial pathogen, especially in vulnerable patient populations. The findings contribute to understanding Bcc infections, their distribution, and emphasize the necessity for accurate identification methods in clinical settings.

In vitro activity of cefiderocol and comparator antibiotics against multidrug-resistant non-fermenting Gram-negative bacilli

Background

This study evaluated the in vitro activity of cefiderocol, ceftazidime/avibactam, and aztreonam/avibactam against clinically important multidrug-resistant non-fermenting Gram-negative bacilli.

Methods

Bacteraemic isolates of 126 multidrug-resistant Acinetobacter baumannii (MDRAB), 110 imipenem-resistant Pseudamoas aeruginosa [including 14 difficult-to-treat resistant P. aeruginosa (DTRPA)], 45 beta-lactam-non-susceptible Burkholderia cepacia complex (BCC), 47 levofloxacin or trimethoprim/sulfamethoxazole-non-susceptible Stenotrophomonas maltophilia and 22 ciprofloxacin-non-susceptible Elizabethkingia spp. collected between 2019 and 2021 were subjected to MIC determination for cefiderocol, ceftazidime/avibactam and aztreonam/avibactam.

Results

The MIC50/90s of cefiderocol for drug-resistant A. baumannii, P. aeruginosa, BCC, S. maltophilia and Elizabethkingia spp. were 0.25/2, 0.25/1, ≤0.06/≤0.06, ≤0.06/0.25 and >32/>32 mg/L, respectively. Cefiderocol inhibited 94.4% (119/126) of MDRAB, 100% of imipenem-resistant P. aeruginosa, 100% of DTRPA and 100% of BCC at an MIC ≤4 mg/L, and 97.9% (46/47) of S. maltophilia at ≤1 mg/L. Ceftazidime/avibactam inhibited 76.4% (84/110) of imipenem-resistant P. aeruginosa, 21.4% (3/14) of DTRPA and 68.9% (31/45) of BCC at an MIC ≤8 mg/L. Aztreonam/avibactam had MIC50/90s of 16/>32, 8/16 and 4/8 mg/L for imipenem-resistant P. aeruginosa, BCC and S. maltophilia, respectively. At ≤8 mg/L, aztreonam/avibactam inhibited 7.1% (1/14) of DTRPA and 93.6% (44/47) of S. maltophilia isolates. Elizabethkingia spp. demonstrated high MICs for cefiderocol, ceftazidime/avibactam and aztreonam/avibactam, with all MIC50s and MIC90s > 32 mg/L.

Conclusion

Cefiderocol may serve as an alternative treatment for multidrug-resistant A. baumannii, P. aeruginosa, BCC and S. maltophilia when other antibiotics have been ineffective or intolerable. The role of ceftazidime/avibactam and aztreonam/avibactam in the management of BCC or S. maltophilia infections warrants further investigation.

Novel Beta Lactam Antibiotics for the Treatment of Multidrug-Resistant Gram-Negative Infections in Children: A Narrative Review

Infections due to carbapenem-resistant Enterobacterales (CRE) are increasingly prevalent in children and are associated with poor clinical outcomes, especially in critically ill patients. Novel beta lactam antibiotics, including ceftolozane-tazobactam, ceftazidime-avibactam, meropenem-vaborbactam, imipenem-cilastatin-relebactam, and cefiderocol, have been released in recent years to face the emerging challenge of multidrug-resistant (MDR) Gram-negative bacteria. Nonetheless, several novel agents lack pediatric indications approved by the Food and Drug Administration (FDA) and the European Medicine Agency (EMA), leading to uncertain pediatric-specific treatment strategies and uncertain dosing regimens in the pediatric population. In this narrative review we have summarized the available clinical and pharmacological data, current limitations and future prospects of novel beta lactam antibiotics in the pediatric population.

New Antimicrobials for the Treatment of Neonatal Sepsis Caused by Multi-Drug-Resistant Bacteria: A Systematic Review

BACKGROUND

Infections by multi-drug-resistant (MDR) organisms are sharply increasing in newborns worldwide. In low and middle-income countries, a disproportionate amount of neonatal sepsis caused by MDR Gram negatives was recently reported. Newborns with infections by MDR organisms with limited treatment options may benefit from novel antimicrobials.

METHODS

We performed a literature search investigating the use in newborns, infants and children of novel antimicrobials for the treatment of MDR Gram negatives, namely ceftazidime/avibactam, ceftolozane/tazobactam, cefiderocol, meropenem/vaborbactam, imipenem/relebactam, and Gram positives with resistance of concern, namely ceftaroline and dalbavancin. PubMed, EMBASE, and Web of Science were searched.

RESULTS

A total of 50 records fulfilled the inclusion criteria. Most articles were case reports or case series, and ceftazidime/avibactam was the most studied agent. All studies showed favorable efficacy and safety profile in newborns and across different age cohorts.

CONCLUSIONS

novel antibiotics may be considered in newborns for the treatment of MDR Gram negatives with limited treatment options and for Gram positives with resistance concerns. Further studies are needed to address their effectiveness and safety in newborns.

Jumping into the future: overcoming pharmacokinetic/pharmacodynamic hurdles to optimize the treatment of severe difficult to treat-Gram-negative infections with novel beta-lactams

INTRODUCTION

The choice of best therapeutic strategy for difficult-to-treat resistance (DTR) Gram-negative infections currently represents an unmet clinical need.

AREAS COVERED

This review provides a critical reappraisal of real-world evidence supporting the role of pharmacokinetic/pharmacodynamic (PK/PD) optimization of novel beta-lactams in the management of DTR Gram-negative infections. The aim was to focus on prolonged and/or continuous infusion administration, penetration rates into deep-seated infections, and maximization of PK/PD targets in special renal patient populations. Retrieved findings were applied to the three most critical clinical scenarios of Gram-negative resistance phenotypes (i.e. carbapenem-resistant Enterobacterales; difficult-to-treat resistant Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii).

EXPERT OPINION

Several studies supported the role of PK/PD optimization of beta-lactams in the management of DTR Gram-negative infections for both maximizing clinical efficacy and preventing resistance emergence. Optimizing antimicrobial therapy with novel beta-lactams based on the so called 'antimicrobial therapy puzzle' PK/PD concepts may represent a definitive jump into the future toward a personalized patient management of DTR Gram negative infections. Establishing a dedicated and coordinated multidisciplinary team and implementing a real-time TDM-guided personalized antimicrobial exposure optimization of novel beta-lactams based on expert clinical pharmacological interpretation, could represent crucial cornerstones for the proper management of DTR Gram-negative infections.

Clinical characteristics and outcomes of non-cystic fibrosis patients with Burkholderia cepacia complex bacteremia at a medical center in Taiwan

BACKGROUND

Burkholderia cepacia complex (BCC) represents a group of multidrug-resistant gram-negative bacteria that cause infections among immunocompromised hosts. Bacteremia occurs in patients who are chronically ill and is associated with substantial morbidity and mortality. The aim of this study was to investigate the clinical characteristics and outcomes of BCC bacteremic patients without cystic fibrosis.

METHODS

We conducted a retrospective study at the National Taiwan University Hospital. Adults with BCC bacteremia from January 2015 to May 2019 were enrolled. The primary outcome was 14-day mortality. Multivariable logistic regression was performed for outcome analysis.

RESULTS

One-hundred and ninety-five patients were analyzed and their mean age was 67 years. Over 95% of the BCC isolates were susceptible to trimethoprim/sulfomethoxazole (TMP/SXT). Levofloxacin resistance rates were high, with only 25.1% of isolates being susceptible. Pairwise comparisons were made between different definitive regimens including meropenem-monotherapy, ceftazidime-monotherapy, levofloxacin-monotherapy, TMP/SXT-monotherapy, tigecycline-monotherapy as well as combination versus monotherapy. No regimen was significantly associated with survival in our study. Multivariable logistic regression showed that the Pitt bacteremia score (adjust odds ratio [aOR],1.46; 95% confidence interval [CI],1.19-1.79; p < 0.001), underlying metastatic cancer (aOR, 2.73; 95% CI, 1.01-7.39; p = 0.047), inappropriate definitive treatment independently predicted greater 14-day mortality (aOR, 8.21; 95% CI, 2.49-27.08; p < 0.001).

CONCLUSIONS

No single regimen is associated with improved mortality. After adjusting for other potential confounders, our data suggest selection of an appropriate antibiotic provide better clinical outcomes among patients with BCC bacteremia.

Ceftazidime/Avibactam in Ventilator-Associated Pneumonia Due to Difficult-to-Treat Non-Fermenter Gram-Negative Bacteria in COVID-19 Patients: A Case Series and Review of the Literature

Ventilator-associated pneumonia (VAP) in critically ill patients with COVID-19 represents a very huge global threat due to a higher incidence rate compared to non-COVID-19 patients and almost 50% of the 30-day mortality rate. Pseudomonas aeruginosa was the first pathogen involved but uncommon non-fermenter gram-negative organisms such as Burkholderia cepacea and Stenotrophomonas maltophilia have emerged as other potential etiological causes. Against carbapenem-resistant gram-negative microorganisms, Ceftazidime/avibactam (CZA) is considered a first-line option, even more so in case of a ceftolozane/tazobactam resistance or shortage. The aim of this report was to describe our experience with CZA in a case series of COVID-19 patients hospitalized in the ICU with VAP due to difficult-to-treat (DTT) P. aeruginosa, Burkholderia cepacea, and Stenotrophomonas maltophilia and to compare it with data published in the literature. A total of 23 patients were treated from February 2020 to March 2022: 19/23 (82%) VAPs were caused by Pseudomonas spp. (16/19 DTT), 2 by Burkholderia cepacea, and 6 by Stenotrophomonas maltophilia; 12/23 (52.1%) were polymicrobial. Septic shock was diagnosed in 65.2% of the patients and VAP occurred after a median of 29 days from ICU admission. CZA was prescribed as a combination regimen in 86% of the cases, with either fosfomycin or inhaled amikacin or cotrimoxazole. Microbiological eradication was achieved in 52.3% of the cases and the 30-day overall mortality rate was 14/23 (60.8%). Despite the high mortality of critically ill COVID-19 patients, CZA, especially in combination therapy, could represent a valid treatment option for VAP due to DTT non-fermenter gram-negative bacteria, including uncommon pathogens such as Burkholderia cepacea and Stenotrophomonas maltophilia.

Ceftazidime-Avibactam as Salvage Therapy in Pediatric Liver Transplantation Patients with Infections Caused by Carbapenem-Resistant Enterobacterales

Objective

There are few therapeutic options for infections caused by carbapenem-resistant Enterobacterales (CRE) in children following liver transplantation. Ceftazidime-avibactam (CAZ-AVI), a recently licensed antibacterial in China, was utilized as a salvage therapy against CRE in our center, and its efficacy and safety were therefore assessed.

Methods

The retrospective, observational study was conducted at the First Affiliated Hospital of Zhejiang University. Pediatric liver transplantation patients (≤12 years) who received CAZ-AVI as a salvage therapy against CRE infections were included from January 2020 to December 2021. Clinical success and all-cause death during hospitalization were the primary outcomes. Recurrence of infection, drug-related adverse events, and changes in inflammatory biomarkers were collected.

Results

Six children were enrolled, with a median age of 10.1 (interquartile range (IQR) 5.5–13.8) months. Primary intraperitoneal infections occurred in all patients, with five patients developing bloodstream infections. KPC carbapenemases were detected in most isolates, and the susceptibility results showed general sensitivity to tigecycline, polymyxin B, and CAZ-AVI. Tigecycline-based therapy was taken as the initial treatment and withdrawn because of clinical failure (5 cases) or cholestasis (1 case). After CRE infection, the median time to convert to CAZ-AVI was 7.5 (IQR 7.0–8.8) days, and the median CAZ-AVI treatment length was 21.0 (IQR 20.3–28.5) days. Clinical success was achieved in all patients, with a zero percent all-cause death rate. No CRE infections recurred throughout hospitalization, and no resistance to CAZ-AVI was detected. Patients experienced vomiting (1/6), skin rash (1/6), and a transient increase in cystatin C (2/6), γ-glutamyltransferase (2/6), and alkaline phosphatase (3/6).

Conclusion

CAZ-AVI was shown to be a successful salvage treatment for CRE infection in pediatric liver transplant recipients, with minor and temporary drug-related side effects.

Antibiotic Therapy for Difficult-to-Treat Infections in Lung Transplant Recipients: A Practical Approach

Lung transplant recipients are at higher risk to develop infectious diseases due to multi-drug resistant pathogens, which often chronically colonize the respiratory tract before transplantation. The emergence of these difficult-to-treat infections is a therapeutic challenge, and it may represent a contraindication to lung transplantation. New antibiotic options are currently available, but data on their efficacy and safety in the transplant population are limited, and clinical evidence for choosing the most appropriate antibiotic therapy is often lacking. In this review, we provide a summary of the best evidence available in terms of choice of antibiotic and duration of therapy for MDR/XDR P. aeruginosa, Burkholderia cepacia complex, Mycobacterium abscessus complex and Nocardia spp. infections in lung transplant candidates and recipients.

The anti-virulence activity of the non-mevalonate pathway inhibitor FR900098 towards Burkholderia cenocepacia is maintained during experimental evolution

Burkholderia cenocepacia infections are difficult to treat and there is an urgent need for alternative (combination) treatments. The use of anti-virulence therapies in combination with antibiotics is a possible strategy to increase the antimicrobial susceptibility of the pathogen and to slow down the development of resistance. In the present study we evaluated the β-lactam and colistin-potentiating activity, and anti-virulence effect of the non-mevalonate pathway inhibitor FR900098 against B. cenocepacia in various in vitro and in vivo models. In addition, we evaluated whether repeated exposure to FR900098 alone or when combined with ceftazidime leads to increased resistance. FR900098 potentiated the activity of colistin and several β-lactam antibiotics (aztreonam, cefepime, cefotaxime, ceftazidime, mecillinam and piperacillin) but not of imipenem and meropenem. When used alone or in combination with ceftazidime, FR900098 increased the survival of infected Galleria mellonella and Caenorhabditis elegans. Furthermore, combining ceftazidime with FR900098 resulted in a significant inhibition of the biofilm formation of B. cenocepacia. Repeated exposure to FR900098 in the C. elegans infection model did not lead to decreased activity, and the susceptibility of the evolved B. cenocepacia HI2424 lineages to ceftazidime, FR900098 and the combination of both remained unchanged. In conclusion, FR900098 reduces B. cenocepacia virulence and potentiates ceftazidime in an in vivo C. elegans model, and this activity is not lost during the experimental evolution experiment carried out in the present study.

Multiresistant organisms: bacteria and beyond

PURPOSE OF REVIEW

Infections with multiresistant organisms are an emerging problem, cause early mortality post lung transplantation and are sometimes associated with graft dysfunction. Frequently they raise questions about the selection of lung transplant candidates and therapeutic management post lung transplantation. There are no guidelines and management must be individualized. This review summarizes the available therapeutic options in cases of multidrug-resistant (MDR) organisms and outcomes after lung transplant.

RECENT FINDINGS

Improvements in diagnosis, new and more effective drugs and the experience gained in the management of these infections in lung transplantation, lead to a more optimistic horizon than that found a decade ago.

SUMMARY

Update on the management of Burkholderia cepacia complex, Mycobacterium abscessus complex, Aspergillus spp., Scedosporium spp. and Lomentospora prolificans infections. This review clarifies current posttransplant outcomes and adds a little hope in these scenarios.

Intravenous Ceftazidime-Avibactam in Extremely Premature Neonates With Carbapenem-Resistant Enterobacteriaceae: Two Case Reports

The increasing use of carbapenems has contributed to a notable distribution of carbapenem-resistant Enterobacteriaceae (CRE). Recently, the incidence of CRE-associated infections is increasing significantly in NICUs, which pose a grave challenge to clinical treatment. We report 2 cases of IV ceftazidimeavibactam use to treat CRE infections in extremely premature neonates. The first case was diagnosed with bacteraemia and meningitis and the second one was diagnosed with bacteraemia only. Due to the lack of neonatal-specific information for IV ceftazidime-avibactam, the usual pediatric dose (62.5 mg/kg/dose every 8 hours) was used in these patients. Clinical cure occurred in these 2 patients. Although blood cultures became sterile after starting ceftazidime-avibactam in the second case, the patient died, presumably owing to sepsis or various causes, such as prematurity and chronic lung disease. Large and randomized studies are necessary to ensure the safety and efficacy of IV ceftazidime-avibactam for the treatment of neonates with sepsis caused by multidrug resistant organisms.

Continuous versus intermittent infusion of antibiotics in Gram-negative multidrug-resistant infections

PURPOSE OF REVIEW

The aim of this review was to perform a critical reappraisal of the real-world evidence supporting administration by prolonged infusion of novel beta-lactams for the management of multidrug-resistant Gram-negative infections.

RECENT FINDINGS

Real-world evidence support the use of novel beta-lactams by prolonged infusion over intermittent infusion in terms of achieving aggressive pharmacokinetic/pharmacodynamic (PK/PD) target for either maximizing efficacy and clinical outcome or suppressing the emergence of resistance development. Continuous infusion of ceftolozane-tazobactam showed a marked superiority toward both intermittent and extended infusion (EI) in achieving a PK/PD target of 100%fT> 4 X MIC in infections caused by less-susceptible Pseudomonas aeruginosa isolates. No resistance development was found in critically ill or immunocompromised patients treated with EI ceftolozane-tazobactam compared to intermittent infusion. Prolonged infusion of ceftazidime-avibactam was negatively associated with mortality in patients affected by Klebsiella pneumoniae carbapenemase-producing K. pneumoniae infections. Different challenging scenarios (patients showing augmented renal clearance of affected by deep-seated infections) could benefit from prolonged infusion to optimize the efficacy of novel agents.

SUMMARY

Although available data are still limited, real-world evidence regarding mainly ceftolozane-tazobactam and ceftazidime-avibactam could support the administration of novel beta-lactams by prolonged infusion in some specific scenarios in which achievement of aggressive PK/PD target is quite challenging.

Does Cefiderocol Have a Potential Role in Cystic Fibrosis Pulmonary Exacerbation Management?

Cystic fibrosis (CF) is associated with frequent pulmonary exacerbations and the need for novel antibiotics against antimicrobial resistance. Cefiderocol is a newly approved therapeutic option active against a variety of multidrug resistant (MDR) bacteria such as gram-negative species commonly encountered by CF patients. This review describes the potential role of cefiderocol against Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Achromobacter xylosoxidans, and Burkholderia cepacia complex. Cefiderocol is a potential therapeutic option for MDR pathogens with minimum inhibitory concentrations (MICs) of ≤4 mg/L. Due to the lack of in vivo evidence in the CF population, cefiderocol may be utilized in patients in which alternative options are lacking due to MDR organisms or rapid pulmonary decline.

Activity of imipenem-relebactam against multi-drug and extensively-drug resistant Burkholderia cepacia complex and Burkholderia gladioli

The Burkholderia cepacia complex (Bcc) and Burkholderia gladioli are opportunistic pathogens that most commonly infect persons with cystic fibrosis or compromised immune systems. Members of the Burkholderia genus are intrinsically multidrug resistant (MDR), possessing both a PenA carbapenemase and an AmpC β-lactamase, which renders treatment of infection due to these species problematic. Here, we tested the β-lactam-β-lactamase inhibitor combination, imipenem-relebactam, against a panel of MDR Bcc and B. gladioli. The addition of relebactam to imipenem dramatically lowered the MICs for Bcc and B. gladioli with only 16% of isolates testing susceptible to imipenem vs. 71.3% being susceptible to the imipenem-relebactam combination. While ceftazidime-avibactam remained the most potent combination drug against this panel of Bcc and B. gladioli, imipenem-relebactam was active against 71.4% of the ceftazidime-avibactam-resistant isolates. Relebactam demonstrated potent inactivation of the Burkholderia multivorans PenA1 with a K_{i app} value of 3.2 μM. Timed mass spectrometry revealed that PenA1 formed a very stable adduct with relebactam, without any detectable desulfation up to 24 hours. Based on our results, imipenem-relebactam may represent an alternative salvage therapy for Bcc and B. gladioli infection, especially in cases where the isolates are resistant to ceftazidime-avibactam.

New Perspectives on Antimicrobial Agents: Cefiderocol

Bacterial resistance to carbapenem agents has reached alarming levels. Accordingly, collaborative efforts between national and international organizations and the pharmaceutical industry have led to an impressive expansion of commercially available β-lactam agents in recent years. No available agent comes close to the broad range of activity afforded by cefiderocol, a novel siderophore-cephalosporin conjugate. The novelty of and need for cefiderocol are clear, but available clinical data are conflicting, leaving infectious diseases specialists puzzled as to when to prescribe this agent in clinical practice. After a brief overview of cefiderocol pharmacokinetics and pharmacodynamics, safety data, cefiderocol susceptibility testing, and putative mechanisms of cefiderocol resistance, this review focuses on determining cefiderocol's role in the management of specific pathogens, including carbapenem-resistant Acinetobacter baumannii complex, carbapenem-resistant Pseudomonas aeruginosa, carbapenem-resistant Enterobacterales, and less commonly identified glucose-nonfermenting organisms such as Stenotrophomonas maltophilia, Burkholderia species, and Achromobacter species. Available preclinical, clinical trial, and postmarketing data are summarized for each organism, and each section concludes with our opinions on where to position cefiderocol as a clinical therapeutic.

Pharmacoepidemiology of Ceftazidime-Avibactam Use: A Retrospective Cohort Analysis of 210 US Hospitals

BACKGROUND

Ceftazidime-avibactam has in vitro activity against some carbapenem-resistant gram-negative infections (GNIs), and therefore may be a useful alternative to more toxic antibiotics such as colistin. Understanding ceftazidime-avibactam uptake and usage patterns would inform hospital formularies, stewardship, and antibiotic development.

METHODS

A retrospective cohort study assessed inpatient encounters in the Vizient database. Ceftazidime-avibactam and colistin administrations were categorized into presumed empiric (3 consecutive days of therapy or less with qualifying exclusions) versus targeted therapy (≥4 consecutive days of therapy) for presumed carbapenem-resistant GNIs. Quarterly percentage change (QPC) using modified Poisson regression and relative change in frequency of targeted ceftazidime-avibactam to colistin encounters was calculated. Factors associated with preferentially receiving targeted ceftazidime-avibactam versus colistin were identified using generalized estimating equations.

RESULTS

Between 2015 quarter (q) 1 and 2017q4, ceftazidime-avibactam was administered 21 215 times across 1901 encounters. Inpatient prescriptions for ceftazidime-avibactam increased from 0.44/10 000 hospitalizations in 2015q1 to 7.7/10 000 in 2017q4 (QPC, +11%; 95% CI, 10-13%; P < .01), while conversely colistin prescriptions decreased quarterly by 5% (95% CI, 4-6%; P < .01). Ceftazidime-avibactam therapy was categorized as empiric 25% of the time, targeted 65% of the time, and indeterminate 10% of the time. Patients with chronic kidney disease were twice as likely to receive targeted ceftazidime-avibactam versus colistin (RR, 2.02; 95% CI, 1.82-2.25), whereas those on dialysis were less likely to receive ceftazidime-avibactam than colistin (RR, 0.71; 95% CI, .61-.83).

CONCLUSIONS

Since approval in 2015, ceftazidime-avibactam use has grown for presumed carbapenem-resistant GNIs, while colistin has correspondingly declined. Renal function drove the choice between ceftazidime-avibactam and colistin as targeted therapy.

New β-Lactam-β-Lactamase Inhibitor Combinations

The limited armamentarium against drug-resistant Gram-negative bacilli has led to the development of several novel β-lactam-β-lactamase inhibitor combinations (BLBLIs). In this review, we summarize their spectrum of in vitro activities, mechanisms of resistance, and pharmacokinetic-pharmacodynamic (PK-PD) characteristics. A summary of available clinical data is provided per drug. Four approved BLBLIs are discussed in detail. All are options for treating multidrug-resistant (MDR) Enterobacterales and Pseudomonas aeruginosa Ceftazidime-avibactam is a potential drug for treating Enterobacterales producing extended-spectrum β-lactamase (ESBL), Klebsiella pneumoniae carbapenemase (KPC), AmpC, and some class D β-lactamases (OXA-48) in addition to carbapenem-resistant Pseudomonas aeruginosa Ceftolozane-tazobactam is a treatment option mainly for carbapenem-resistant P. aeruginosa (non-carbapenemase producing), with some activity against ESBL-producing Enterobacterales Meropenem-vaborbactam has emerged as treatment option for Enterobacterales producing ESBL, KPC, or AmpC, with similar activity as meropenem against P. aeruginosa Imipenem-relebactam has documented activity against Enterobacterales producing ESBL, KPC, and AmpC, with the combination having some additional activity against P. aeruginosa relative to imipenem. None of these drugs present in vitro activity against Enterobacterales or P. aeruginosa producing metallo-β-lactamase (MBL) or against carbapenemase-producing Acinetobacter baumannii Clinical data regarding the use of these drugs to treat MDR bacteria are limited and rely mostly on nonrandomized studies. An overview on eight BLBLIs in development is also provided. These drugs provide various levels of in vitro coverage of carbapenem-resistant Enterobacterales, with several drugs presenting in vitro activity against MBLs (cefepime-zidebactam, aztreonam-avibactam, meropenem-nacubactam, and cefepime-taniborbactam). Among these drugs, some also present in vitro activity against carbapenem-resistant P. aeruginosa (cefepime-zidebactam and cefepime-taniborbactam) and A. baumannii (cefepime-zidebactam and sulbactam-durlobactam).

Optimal Management of Complicated Infections in the Pediatric Patient: The Role and Utility of Ceftazidime/Avibactam

Antimicrobial resistance poses a substantial threat to global public health. The pursuit of new antibiotics has decreased and very few options have been investigated for the treatment of complicated multidrug-resistant Gram-negative (MDR-GN) infections in adult population and even less in pediatric patients. Ceftazidime-avibactam (CAZ-AVI) is novel cephalosporin/β-lactamase inhibitor (BL-BLI) combination with broad antibacterial spectrum. The aim of this review is to describe the current and future role CAZ-AVI in the pediatric population with suspected or confirmed MDR-GN infections.

Carbapenem-Resistant Gram-Negative Bacterial Infections in Children

Carbapenem-resistant organisms (CRO) are a major global public health threat. Enterobacterales hydrolyze almost all β-lactams through carbapenemase production. Infections caused by CRO are challenging to treat due to the limited number of antimicrobial options. This leads to significant morbidity and mortality. Over the last few years, several new antibiotics effective against CRO have been approved. Some of them (e.g., plazomicin or imipenem-cilastatin-relebactam) are currently approved for use only by adults; others (e.g., ceftazidime-avibactam) have recently been approved for use by children. Recommendations for antibiotic therapy of CRO infections in pediatric patients are based on evidence mainly from adult studies. The availability of pediatric pharmacokinetic and safety data is the cornerstone to broaden the use of proposed agents in adults to the pediatric population. This article provides a comprehensive review of the current knowledge regarding infections caused by CRO with a focus on children, which includes epidemiology, risk factors, outcomes, and antimicrobial therapy management, with particular attention being given to new antibiotics.

"Switching Partners": Piperacillin-Avibactam Is a Highly Potent Combination against Multidrug-Resistant Burkholderia cepacia Complex and Burkholderia gladioli Cystic Fibrosis Isolates

In persons with cystic fibrosis (CF), airway infection with Burkholderia cepacia complex (Bcc) species or Burkholderia gladioli presents a significant challenge due to inherent resistance to multiple antibiotics. Two chromosomally encoded inducible β-lactamases, a Pen-like class A and AmpC are produced in Bcc and B. gladioli Previously, ceftazidime-avibactam demonstrated significant potency against Bcc and B. gladioli isolated from the sputum of individuals with CF; however, 10% of the isolates tested resistant to ceftazidime-avibactam. Here, we describe an alternative antibiotic combination to overcome ceftazidime-avibactam resistance. Antimicrobial susceptibility testing was performed on Bcc and B. gladioli clinical and control isolates. Biochemical analysis was conducted on purified PenA1 and AmpC1 β-lactamases from Burkholderia multivorans ATCC 17616. Analytic isoelectric focusing and immunoblotting were conducted on cellular extracts of B. multivorans induced by various β-lactams or β-lactam-β-lactamase inhibitor combinations. Combinations of piperacillin-avibactam, as well as piperacillin-tazobactam plus ceftazidime-avibactam (the clinically available counterpart), were tested against a panel of ceftazidime-avibactam nonsusceptible Bcc and B. gladioli The piperacillin-avibactam and piperacillin-tazobactam-ceftazidime-avibactam combinations restored susceptibility to 99% of the isolates tested. Avibactam is a potent inhibitor of PenA1 (apparent inhibitory constant [K_{i app}] = 0.5 μM), while piperacillin was found to inhibit AmpC1 (K_{i app} = 2.6 μM). Moreover, piperacillin, tazobactam, ceftazidime, and avibactam, as well as combinations thereof, did not induce expression of bla _penA1 and bla _ampC1 in the B. multivorans ATCC 17616 background. When ceftazidime-avibactam is combined with piperacillin-tazobactam, the susceptibility of Bcc and B. gladioli to ceftazidime and piperacillin is restored in vitro Both the lack of bla _penA1 induction and potent inactivation of PenA1 by avibactam likely provide the major contributions toward susceptibility. With in vivo validation, piperacillin-tazobactam-ceftazidime-avibactam may represent salvage therapy for individuals with CF and highly drug-resistant Bcc and B. gladioli infections.

Lung transplantation in two cystic fibrosis patients infected with previously pandrug-resistant Burkholderia cepacia complex treated with ceftazidime-avibactam

We describe two cystic fibrosis patients infected with pandrug-resistant Burkholderia cepacia complex, with the exception of ceftazidime-avibactam, who received prophylaxis with this antibiotic during lung transplantation. Although both patients had a post-operative relapse of respiratory infection, one with positive blood cultures, ceftazidime-avibactam treatment yielded a favourable outcome. 12 months after transplantation, one patient presented an excellent clinical outcome. However, the other patient died 10 months later due to severe B. cepacia sinusitis with intracranial invasion.

Burkholderia Cepacia Complex Causing Pneumonia in an Immunocompetent Non-Cystic Fibrosis Patient: Case Report and Review of Literature

BACKGROUND

Burkholderia cepacia complex is widespread in the environment and has been recognized as a cause of opportunistic pulmonary infections, particularly in patients with Cystic Fibrosis (CF). The natural ecology of the bacteria as part of plant growth-promoting rhizosphere provides stark contrast to its infectious potential. Its preponderance as a nosocomial pathogen may be due to its ability to survive in antiseptic solutions, contaminate equipments and intrinsic antimicrobial resistance.

CASE

An elderly, diabetic male was evaluated for hemoptysis, fever and cough. Chest computed tomography showed a thick walled cavity in the left lung and hilar lymphadenopathy. Sputum examination showed Gram negative bacilli and no acid fast bacilli. Sputum culture yielded growth of non-fermentative Gram negative bacilli on two occasions, but blood culture was sterile. The isolate was identified as B. cepacia by Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS). The patient's general condition remained poor and in spite of initiation of antibiotics, the patient expired after an episode of massive hemoptysis.

CONCLUSION

This report raises concerns regarding the spread and severity of B. cepacia infection in non-compromised patients in the community and the need to suspect and identify it. Since the organism is inherently resistant to antipseudomonal penicillins, aminoglycosides and polymyxin B, differentiation from Pseudomonas spp. and determining antimicrobial susceptibility is paramount for treatment.