Dual ß-lactam for treatment of pulmonary Mycobacterium abscessus in a child.

Treatment of Mycobacterium abscessus infection presents significant challenges, exacerbated by the emergence of macrolide-resistant strains that necessitate the use of multiple antimicrobials in combination and carry the potential for significant toxic effects. Select dual beta-lactam combinations, with or without beta-lactamase inhibitors, have been shown to be highly active in vitro. Herein, we describe a 6-year-old child with underlying mild bilateral lower lobe cylindrical bronchiectatic lung disease who developed pulmonary Mycobacterium abscessus infection and was treated with a multi-drug regimen including two ß-lactam antibiotics, achieving both early clinical and microbiological cure. This case highlights the potential benefit of dual ß-lactam therapy for the treatment of drug-resistant Mycobacterium abscessus infection.

Case Commentary: Another prong of attack? Topical antibiotic instillation with negative pressure wound therapy for nontuberculous mycobacterial skin and soft tissue infections.

Nontuberculous mycobacteria (NTM) skin infections remain therapeutically challenging. Given the diversity in infections, host responses, and antimicrobials, clinical guidelines are often built on case series and observational studies. In this commentary, we respond to a paper by Stemkens et al. that introduces an emerging strategy: adjunctive negative pressure wound therapy with instillation and dwell time combined with topical antibiotics for refractory NTM skin and soft tissue infections. We delve into the primary considerations surrounding this innovative approach.

"One-Two Punch": Synergistic ß-Lactam Combinations for Mycobacterium abscessus and Target Redundancy in the Inhibition of Peptidoglycan Synthesis Enzymes.

Mycobacterium abscessus subsp. abscessus is one of the most difficult pathogens to treat and its incidence in disease is increasing. Dual ß-lactam combinations act synergistically in vitro but are not widely employed in practice. A recent study shows that a combination of imipenem and ceftaroline significantly lowers the minimum inhibitory concentration of clinical isolates, despite both drugs targeting the same peptidoglycan synthesis enzymes. The underlying mechanism of this effect provides a basis for further investigations of dual ß-lactam combinations in the treatment of M. abscessus subsp. abscessus, eventually leading to a clinical trial. Furthermore, dual ß-lactam strategies may be explored for other difficult mycobacterial infections.

Insights into the l,d-Transpeptidases and d,d-Carboxypeptidase of Mycobacterium abscessus: Ceftaroline, Imipenem, and Novel Diazabicyclooctane Inhibitors.

Mycobacterium abscessus is a highly drug-resistant nontuberculous mycobacterium (NTM). Efforts to discover new treatments for M. abscessus infections are accelerating, with a focus on cell wall synthesis proteins (M. abscessus l,d-transpeptidases 1 to 5 [LdtMab1 to LdtMab5] and d,d-carboxypeptidase) that are targeted by ß-lactam antibiotics. A challenge to this approach is the presence of chromosomally encoded ß-lactamase (BlaMab). Using a mechanism-based approach, we found that a novel ceftaroline-imipenem combination effectively lowered the MICs of M. abscessus isolates (MIC50 ≤ 0.25 µg/ml; MIC90 ≤ 0.5 µg/ml). Combining ceftaroline and imipenem with a ß-lactamase inhibitor, i.e., relebactam or avibactam, demonstrated only a modest effect on susceptibility compared to each of the ß-lactams alone. In steady-state kinetic assays, BlaMab exhibited a lower Ki app (0.30 ± 0.03 µM for avibactam and 136 ± 14 µM for relebactam) and a higher acylation rate for avibactam (k2/K = 3.4 × 105 ± 0.4 × 105 M-1 s-1 for avibactam and 6 × 102 ± 0.6 × 102 M-1 s-1 for relebactam). The kcat/Km was nearly 10-fold lower for ceftaroline fosamil (0.007 ± 0.001 µM-1 s-1) than for imipenem (0.056 ± 0.006 µM-1 s-1). Timed mass spectrometry captured complexes of avibactam and BlaMab, LdtMab1, LdtMab2, LdtMab4, and d,d-carboxypeptidase, whereas relebactam bound only BlaMab, LdtMab1, and LdtMab2 Interestingly, LdtMab1, LdtMab2, LdtMab4, LdtMab5, and d,d-carboxypeptidase bound only to imipenem when incubated with imipenem and ceftaroline fosamil. We next determined the binding constants of imipenem and ceftaroline fosamil for LdtMab1, LdtMab2, LdtMab4, and LdtMab5 and showed that imipenem bound >100-fold more avidly than ceftaroline fosamil to LdtMab1 and LdtMab2 (e.g., Ki app or Km of LdtMab1 = 0.01 ± 0.01 µM for imipenem versus 0.73 ± 0.08 µM for ceftaroline fosamil). Molecular modeling indicates that LdtMab2 readily accommodates imipenem, but the active site must widen to ≥8 Å for ceftaroline to enter. Our analysis demonstrates that ceftaroline and imipenem binding to multiple targets (l,d-transpeptidases and d,d-carboxypeptidase) and provides a mechanistic rationale for the effectiveness of this dual ß-lactam combination in M. abscessus infections.

Evaluation of in vitro activity of ceftazidime/avibactam and ceftolozane/tazobactam against MDR Pseudomonas aeruginosa isolates from Qatar.

OBJECTIVES: To investigate the in vitro activity of ceftazidime/avibactam and ceftolozane/tazobactam against clinical isolates of MDR Pseudomonas aeruginosa from Qatar, as well as the mechanisms of resistance. METHODS: MDR P. aeruginosa isolated between October 2014 and September 2015 from all public hospitals in Qatar were included. The BD PhoenixTM system was used for identification and initial antimicrobial susceptibility testing, while Liofilchem MIC Test Strips (Liofilchem, Roseto degli Abruzzi, Italy) were used for confirmation of ceftazidime/avibactam and ceftolozane/tazobactam susceptibility. Ten ceftazidime/avibactam- and/or ceftolozane/tazobactam-resistant isolates were randomly selected for WGS. RESULTS: A total of 205 MDR P. aeruginosa isolates were included. Of these, 141 (68.8%) were susceptible to ceftazidime/avibactam, 129 (62.9%) were susceptible to ceftolozane/tazobactam, 121 (59.0%) were susceptible to both and 56 (27.3%) were susceptible to neither. Twenty (9.8%) isolates were susceptible to ceftazidime/avibactam but not to ceftolozane/tazobactam and only 8 (3.9%) were susceptible to ceftolozane/tazobactam but not to ceftazidime/avibactam. Less than 50% of XDR isolates were susceptible to ceftazidime/avibactam or ceftolozane/tazobactam. The 10 sequenced isolates belonged to six different STs and all produced AmpC and OXA enzymes; 5 (50%) produced ESBL and 4 (40%) produced VIM enzymes. CONCLUSIONS: MDR P. aeruginosa susceptibility rates to ceftazidime/avibactam and ceftolozane/tazobactam were higher than those to all existing antipseudomonal agents, except colistin, but were less than 50% in extremely resistant isolates. Non-susceptibility to ceftazidime/avibactam and ceftolozane/tazobactam was largely due to the production of ESBL and VIM enzymes. Ceftazidime/avibactam and ceftolozane/tazobactam are possible options for some patients with MDR P. aeruginosa in Qatar.

Durlobactam, a Diazabicyclooctane ß-Lactamase Inhibitor, Inhibits BlaC and Peptidoglycan Transpeptidases of Mycobacterium tuberculosis.

Peptidoglycan synthesis is an underutilized drug target in Mycobacterium tuberculosis (Mtb). Diazabicyclooctanes (DBOs) are a class of broad-spectrum ß-lactamase inhibitors that also inhibit certain peptidoglycan transpeptidases that are important in mycobacterial cell wall synthesis. We evaluated the DBO durlobactam as an inhibitor of BlaC, the Mtb ß-lactamase, and multiple Mtb peptidoglycan transpeptidases (PonA1, LdtMt1, LdtMt2, LdtMt3, and LdtMt5). Timed electrospray ionization mass spectrometry (ESI-MS) captured acyl-enzyme complexes with BlaC and all transpeptidases except LdtMt5. Inhibition kinetics demonstrated durlobactam was a potent and efficient DBO inhibitor of BlaC (KI app 9.2 ± 0.9 µM, k2/K 5600 ± 560 M-1 s-1) and similar to clavulanate (KI app 3.3 ± 0.6 µM, k2/K 8400 ± 840 M-1 s-1); however, durlobactam had a lower turnover number (tn = kcat/kinact) than clavulanate (1 and 8, respectively). KI app values with durlobactam and clavulanate were similar for peptidoglycan transpeptidases, but ESI-MS captured durlobactam complexes at more time points. Molecular docking and simulation demonstrated several productive interactions of durlobactam in the active sites of BlaC, PonA1, and LdtMt2. Antibiotic susceptibility testing was conducted on 11 Mtb isolates with amoxicillin, ceftriaxone, meropenem, imipenem, clavulanate, and durlobactam. Durlobactam had a minimum inhibitory concentration (MIC) range of 0.5-16 µg/mL, similar to the ranges for meropenem (1-32 µg/mL) and imipenem (0.5-64 µg/mL). In ß-lactam + durlobactam combinations (1:1 mass/volume), MICs were lowered 4- to 64-fold for all isolates except one with meropenem-durlobactam. This work supports further exploration of novel ß-lactamase inhibitors that target BlaC and Mtb peptidoglycan transpeptidases.

Synergistic effects of sulopenem in combination with cefuroxime or durlobactam against Mycobacterium abscessus.

Mycobacterium abscessus (Mab) affects patients with immunosuppression or underlying structural lung diseases such as cystic fibrosis (CF). Additionally, Mab poses clinical challenges due to its resistance to multiple antibiotics. Herein, we investigated the synergistic effect of dual ß-lactams [sulopenem and cefuroxime (CXM)] or the combination of sulopenem and CXM with ß-lactamase inhibitors [BLIs-avibactam (AVI) or durlobactam (DUR)]. The sulopenem-CXM combination yielded low minimum inhibitory concentration (MIC) values for 54 clinical Mab isolates and ATCC19977 (MIC50 and MIC90 ≤0.25 µg/mL). Similar synergistic effects were observed in time-kill studies conducted at concentrations achievable in clinical settings. Sulopenem-CXM outperformed monotherapy, yielding ~1.5 Log10 CFU/mL reduction during 10 days. Addition of BLIs enhanced this antibacterial effect, resulting in an additional reduction of CFUs (~3 Log10 for sulopenem-CXM and AVI and ~4 Log10 for sulopenem-DUR). Exploration of the potential mechanisms of the synergy focused on their interactions with L,D-transpeptidases (Ldts; LdtMab1-LdtMab4), penicillin-binding-protein B (PBP B), and D,D-carboxypeptidase (DDC). Acyl complexes, identified via mass spectrometry analysis, demonstrated the binding of sulopenem with LdtMab2-LdtMab4, DDC, and PBP B and CXM with LdtMab2 and PBP B. Molecular docking and mass spectrometry data suggest the formation of a covalent adduct between sulopenem and LdtMab2 after the nucleophilic attack of the cysteine residue at the ß-lactam carbonyl carbon, leading to the cleavage of the ß-lactam ring and the establishment of a thioester bond linking the LdtMab2 with sulopenem. In conclusion, we demonstrated the biochemical basis of the synergy of sulopenem-CXM with or without BLIs. These findings potentially broaden the selection of oral therapeutic agents to combat Mab. IMPORTANCE: Treating infections from Mycobacterium abscessus (Mab), particularly those resistant to common antibiotics like macrolides, is notoriously difficult, akin to a never-ending struggle for healthcare providers. The rate of treatment failure is even higher than that seen with multidrug-resistant tuberculosis. The role of combination ß-lactams in inhibiting L,D-transpeptidation, the major peptidoglycan crosslink reaction in Mab, is an area of intense investigation, and clinicians have utilized this approach in the treatment of macrolide-resistant Mab, with reports showing clinical success. In our study, we found that cefuroxime and sulopenem, when used together, display a significant synergistic effect. If this promising result seen in lab settings, translates well into real-world clinical effectiveness, it could revolutionize current treatment methods. This combination could either replace the need for more complex intravenous medications or serve as a "step down" to an oral medication regimen. Such a shift would be much easier for patients to manage, enhancing their comfort and likelihood of sticking to the treatment plan, which could lead to better outcomes in tackling these tough infections. Our research delved into how these drugs inhibit cell wall synthesis, examined time-kill data and binding studies, and provided a scientific basis for the observed synergy in cell-based assays.

A 40-Year-Old Female With Mycobacterium abscessus Successfully Treated With a Dual Beta-Lactam Combination.

Nontuberculous mycobacteria (NTM) infections are difficult to treat conditions, specially Mycobacterium abscessus (Mab) lung disease. The most recent ATS/ERS/ESCMID/IDSA clinical practice guidelines (2020) recommend regimens of multiple intravenous (IV) and oral antibiotics. Recent in vitro studies on M. abscessus show that the combination of two beta-lactam antibiotics, as well as select beta-lactamase inhibitors, provides significant synergy in its treatment. We present the first in vivo case of the successful treatment of Mycobacterium abscessus with imipenem and amoxicillin in addition to macrolides, clofazimine, and inhaled liposomal amikacin.

Eradicating Pulmonary Mycobacterium abscessus: The Promise of Dual ß-Lactam Therapy.

Macrolide resistance has rendered the treatment of Mycobacterium abscessus extremely difficult and is fueling a crisis. Recently, there has been dramatically increased incidence of infections by M abscessus. Select dual ß-lactam combinations have shown promising in vitro results. Herein, we present a patient whose M abscessus infection cured using dual ß-lactams as part of multidrug regimen.

Containment of COVID-19 outbreak at a veterans affairs community living center.

Asymptomatic and pre-symptomatic staff and residents likely contribute to widespread transmission of COVID-19 in long-term care settings. Here, we describe the successful containment of a COVID-19 outbreak on one floor of a 163-bed Veterans Affairs (VA) Community Living Center (CLC). Testing using nasopharyngeal swabs with a rapid turn-around-time identified 3 of 28 (11%) residents and 2 of 41 (5%) healthcare personnel (HCP) with COVID-19. Both HCP likely worked on the floor while pre-symptomatic. When one HCP reported a cough to the secondary (employee) screening clinic, she was erroneously advised to work. Protocols to limit the risk for HCP to import COVID-19 were reinforced with Community Living Center staff as well as with personnel in secondary screening. Further, the CLC implemented an expanded screening tool that assessed residents for typical and atypical symptoms of COVID-19. No further cases of COVID-19 were detected on the CLC floor in the subsequent 6 weeks. Swift recognition and response helped contain the outbreak and prevent further COVID-19 infections among other residents and staff.

Inhibiting Mycobacterium abscessus Cell Wall Synthesis: Using a Novel Diazabicyclooctane ß-Lactamase Inhibitor To Augment ß-Lactam Action.

Mycobacterium abscessus (Mab) infections are a growing menace to the health of many patients, especially those suffering from structural lung disease and cystic fibrosis. With multidrug resistance a common feature and a growing understanding of peptidoglycan synthesis in Mab, it is advantageous to identify potent ß-lactam and ß-lactamase inhibitor combinations that can effectively disrupt cell wall synthesis. To improve existing therapeutic regimens to address serious Mab infections, we evaluated the ability of durlobactam (DUR), a novel diazobicyclooctane ß-lactamase inhibitor to restore in vitro susceptibilities in combination with ß-lactams and provide a biochemical rationale for the activity of this compound. In cell-based assays, susceptibility of Mab subsp. abscessus isolates to amoxicillin (AMOX), imipenem (IMI), and cefuroxime (CXM) was significantly enhanced with the addition of DUR. The triple drug combinations of CXM-DUR-AMOX and IMI-DUR-AMOX were most potent, with MIC ranges of ≤0.06 to 1 µg/mL and an MIC50/MIC90 of ≤0.06/0.25 µg/mL, respectively. We propose a model by which this enhancement may occur, DUR potently inhibited the ß-lactamase BlaMab with a relative Michaelis constant (Ki app) of 4 × 10-3 ± 0.8 × 10-3 µM and acylation rate (k2/K) of 1 × 107 M-1 s-1. Timed mass spectrometry captured stable formation of carbamoyl-enzyme complexes between DUR and LdtMab2-4 and Mab d,d-carboxypeptidase, potentially contributing to the intrinsic activity of DUR. Molecular modeling showed unique and favorable interactions of DUR as a BlaMab inhibitor. Similarly, modeling showed how DUR might form stable Michaelis-Menten complexes with LdtMab2-4 and Mab d,d-carboxypeptidase. The ability of DUR combined with amoxicillin or cefuroxime and imipenem to inactivate multiple targets such as d,d-carboxypeptidase and LdtMab2,4 supports new therapeutic approaches using ß-lactams in eradicating Mab. IMPORTANCE Durlobactam (DUR) is a potent inhibitor of BlaMab and provides protection of amoxicillin and imipenem against hydrolysis. DUR has intrinsic activity and forms stable acyl-enzyme complexes with LdtMab2 and LdtMab4. The ability of DUR to protect amoxicillin and imipenem against BlaMab and its intrinsic activity along with the dual ß-lactam target redundancy can explain the rationale behind the potent activity of this combination.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid contamination of surfaces on a coronavirus disease 2019 (COVID-19) ward and intensive care unit.

On coronavirus disease 2019 (COVID-19) wards, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid was frequently detected on high-touch surfaces, floors, and socks inside patient rooms. Contamination of floors and shoes was common outside patient rooms on the COVID-19 wards but decreased after improvements in floor cleaning and disinfection were implemented.

Drug-Resistant Tuberculosis: A Glance at Progress and Global Challenges.

Multidrug-resistant Mycobacterium tuberculosis remains a major public health threat; its management poses a significant economic burden. Treatment requires a programmatic approach with access to laboratory services, second-line medications, and adequate clinical resources. In recent years, we have seen rapid developments in diagnostic techniques with whole genome sequencing-based drug susceptibility prediction now in reach, an array of new drugs that transform treatment regimens to purely oral formulations, and a steady stream of multinational trials that inform us about most efficient combinations. Our hope is that the current momentum keeps the ambitious goal to end tuberculosis in 2030 in reach.

SARS-CoV-2 infection in a patient on chronic hydroxychloroquine therapy: Implications for prophylaxis.

People exposed to COVID-19 have a risk of developing disease, and health care workers are at risk at a time when they are badly needed during a health care crisis. Hydroxychloroquine and chloroquine have been used as treatment and are being considered as prophylaxis. Our patient developed COVID-19 while on hydroxychloroquine and although more work is needed, this calls into question the role of these medications as preventive therapy.

Prevalence of Venous Thromboembolism in Critically Ill COVID-19 Patients: Systematic Review and Meta-Analysis.

Background: Recent studies revealed a high prevalence of venous thromboembolism (VTE) events in coronavirus disease 2019 (COVID-19) patients, especially in those who are critically ill. Available studies report varying prevalence rates. Hence, the exact prevalence remains uncertain. Moreover, there is an ongoing debate regarding the appropriate dosage of thromboprophylaxis. Methods: We performed a systematic review and proportion meta-analysis following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We searched PubMed and EMBASE for studies exploring the prevalence of VTE in critically ill COVID-19 patients till 25/07/2020. We pooled the proportion of VTE. Additionally, in a subgroup analysis, we pooled VTE events detected by systematic screening. Finally, in an exploratory analysis, we compared the odds of VTE in patients on prophylactic compared with therapeutic anticoagulation. Results: The review comprised 24 studies and over 2,500 patients. The pooled proportion of VTE prevalence was 0.31 [95% confidence interval (CI) 0.24, 0.39; I 2 94%], of VTE utilizing systematic screening was 0.48 (95% CI 0.33, 0.63; I 2 91%), of deep venous thrombosis was 0.23 (95% CI 0.14, 0.32; I 2 96%), and of pulmonary embolism was 0.14 (95% CI 0.09, 0.20; I 2 90%). Exploratory analysis of few studies, utilizing systematic screening, VTE risk increased significantly with prophylactic, compared with therapeutic anticoagulation [odds ratio (OR) 5.45; 95% CI 1.90, 15.57; I 2 0%]. Discussion: Our review revealed a high prevalence of VTE in critically ill COVID-19 patients. Almost 50% of patients had VTE detected by systematic screening. Higher thromboprophylaxis dosages may reduce VTE burden in this patient's cohort compared with standard prophylactic anticoagulation; however, this is to be ascertained by ongoing randomized controlled trials.

Progressive and disseminated histoplasma infection and hemophagocytic lymphohistiocytosis in an immunocompetent adult.

Hemophagocytic lymphohistiocytosis (HLH) in adults is a life-threatening underdiagnosed disorder that complicates different infectious syndromes and overlaps with sepsis. No guidelines are available for the management of HLH in adults. A high index of suspicion is required in patients with disseminated histoplasmosis.

Impact of Diabetes Mellitus on the Presentation and Response to Treatment of Adults With Pulmonary Tuberculosis in Qatar.

BACKGROUND: Persons with diabetes mellitus (DM) have a 3-fold increased risk of tuberculosis (TB). Atypical radiographic findings and differences in bacteriologic response during anti-TB treatment have been reported in earlier studies; however, the findings have varied. We evaluated the effect of DM on manifestations and response to treatment in adults with pulmonary TB in Qatar. METHODS: The impact of DM on the clinical and radiographic presentations of pulmonary TB and bacteriologic response during anti-TB treatment was evaluated between January 2007 and December 2011, comparing patients with and without DM. This is a retrospective unmatched case-control study conducted at a large national hospital. Cases and controls were randomly selected from patients diagnosed with pulmonary TB over a 5-year period. Sputum culture conversion was assessed after 2 months of anti-TB treatment. RESULTS: Clinical symptoms were similar between patients with and without DM. Patients with DM had a higher initial sputum acid-fast bacillus (AFB) smear grade and were less likely to have cavitary lesions on initial chest radiographs than patients without DM. Of 134 adults with DM and TB, 71 (53%) remained sputum culture positive after 2 months of anti-TB treatment, compared with 36 (27%) patients without DM. CONCLUSIONS: DM was associated with atypical radiographic findings and delayed sputum culture conversion at 2 months in adults with pulmonary TB in Qatar. Increased health education of patients with DM about symptoms of TB, low thresholds for evaluation for active TB, and close monitoring of bacteriologic response to treatment among patients with TB and DM are warranted.

Renal infarction in vascular Ehlers-Danlos syndrome masquerading as pyelonephritis.

Symptoms associated with numerous diseases can be indistinguishable from those of the urinary system disorders because receptors of many visceral organs as well as the body wall transmit sensation through pain fibers shared with the kidneys. Disregarding important family background of genetic disorder can be detrimental for some patients.

Ibrutinib Therapy and Mycobacterium chelonae Skin and Soft Tissue Infection.

Ibrutinib is an irreversible inhibitor of Bruton's tyrosine kinase approved for the treatment of B-cell malignancies. There is growing concern about the risk of opportunistic infections following ibrutinib therapy. Herein, we describe the first case of Mycobacterium chelonae skin and soft tissue infection in a patient receiving ibrutinib and recount the challenges in treating this infection.