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INTRODUCTION: Cytomegalovirus (CMV) is a classic opportunistic infection in transplant recipients. Treatment-refractory CMV infections are of concern, with growing identification of strains that have developed genetic mutations which confer resistance to standard antiviral therapy. Resistant and refractory CMV infections are associated with worse patient outcomes, prolonged hospitalization, and increased healthcare costs. AREAS COVERED: This article provides a comprehensive practical overview of resistant and refractory CMV infections in transplant recipients. We review the updated definitions for these infections, antiviral pharmacology, mechanisms of drug resistance, diagnostic workup, management strategies, and host-related factors including immune optimization. EXPERT OPINION: Resistant and refractory CMV infections are a significant contributor to post-transplant morbidity and mortality. This is likely the result of a combination of prolonged antiviral exposure and active viral replication in the setting of intensive pharmacologic immunosuppression. Successful control of resistant and refractory infections in transplant recipients requires a combination of immunomodulatory optimization and appropriate antiviral drug choice with sufficient treatment duration.

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Despite the significant progress made, CMV infection is one of the most frequent infectious complications in transplant recipients. CMV infections that become refractory or resistant (R/R) to the available antiviral drugs constitute a clinical challenge and are associated with increased morbidity and mortality. Novel anti-CMV therapies have been recently developed and introduced in clinical practice, which may improve the treatment of these infections. In this review, we summarize the treatment options for R/R CMV infections in adult hematopoietic cell transplant and solid organ transplant recipients, with a special focus on newly available antiviral agents with anti-CMV activity, including maribavir and letermovir.

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BACKGROUND: Invasive aspergillosis is associated with significant morbidity and mortality in patients with haematologic malignancies and haematopoietic cell transplant recipients. The prognosis is worse among patients who have failed primary antifungal treatment. OBJECTIVES: We aim to provide guidance on the diagnosis and management of refractory invasive pulmonary aspergillosis. SOURCES: Using PubMed, we performed a review of original articles, meta-analyses, and systematic reviews. CONTENT: We discuss the diagnostic criteria for invasive pulmonary aspergillosis and the evidence on the treatment of primary infection. We outline our diagnostic approach to refractory disease. We propose a treatment algorithm for refractory disease and discuss the role of experimental antifungal agents. IMPLICATIONS: For patients with worsening disease while on antifungal therapy, a thorough diagnostic evaluation is required to confirm the diagnosis of aspergillosis and exclude another concomitant infection. Treatment should be individualized. Current options include switching to another triazole, transitioning to a lipid formulation of amphotericin B, or using combination antifungal therapy.

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INTRODUCTION: Solid organ transplantation (SOT) and hematopoietic stem cell transplantation (HSCT) recipients are susceptible to cytomegalovirus (CMV) infection. The incidence of refractoriness to antivirals, with or without resistance, is unclear. The purpose of this review was to describe the epidemiology of refractory CMV infection in Spain to understand the current unmet needs. METHODS: PubMed, EMBASE, Cochrane and MEDES were searched systematically for relevant articles. We included randomized controlled trials and observational studies published during the period from January 1990 to June 2021. RESULTS: From 212 screened records, we selected 19 papers including 1973 transplant recipients. Refractory infection ranged from 3 to 10% in studies with SOT recipients. The incidence of CMV resistance ranged from 1% to 36% in these patients. The incidence of CMV refractory infection in HSCT recipients ranged from 11 to 50%, while values for resistant infection ranged from 0% to 21%. CONCLUSION: The wide range of definitions and values observed does not allow us to establish the true incidence of refractory CMV infection with or without resistances in SOT and HSCT patients in Spain. This review highlights the gap between clinical practice and clinical trials' definitions which needed to be updated to be easier followed in current clinical practice.

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OBJECTIVES: To explore the molecular characteristics of rpoB, encoding ß-subunit of DNA-directed RNA polymerase, and unravel the link to rifabutin-resistance in patients with refractory Helicobacter pylori infection. METHODS: From January 2018-March 2021, a total of 1590 patients were screened for eligibility to participate in the study. Patients with refractory H. pylori infection were confirmed by using the (13C)-urea breath assay. All enrolled patients underwent esophagogastroduodenoscopy, and biopsies were taken for H. pylori culture and antibacterial susceptibility testing. Sequence analysis of rpoB was conducted for all rifabutin-resistant isolates. RESULTS: In total, 70 patients were diagnosed with refractory H. pylori infection, and 39 isolates were successfully cultured. Amongst, 10 isolates were identified as rifabutin-resistance and nine isolates exhibited at least one amino acid substitution in RpoB. Isolates with a minimal inhibitory concentration >32 mg/l displayed a higher number of mutational changes in RpoB than the others. Additionally, more amino acid substitutions in RpoB correlated with developing a higher minimal inhibitory concentration for H. pylori rifabutin-resistance. CONCLUSION: Our findings highlight the relationship between rifabutin-resistance in refractory H. pylori infection and specific mutations in RpoB, which will aid the clinical selection of appropriate antibacterial agents with better therapeutic effects.

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BACKGROUND: Due to increasing resistance rates of Helicobacter pylori (H. pylori) to different antibiotics, failures in eradication therapies are becoming more frequent. Even though eradication criteria and treatment algorithms for first-line and second-line therapy against H. pylori infection are well-established, there is no clear recommendation for third-line and rescue therapy in refractory H. pylori infection. AIM: To perform a systematic review evaluating the efficacy and safety of rescue therapies against refractory H. pylori infection. METHODS: A systematic search of available rescue treatments for refractory H. pylori infection was conducted on the National Library of Medicine's PubMed search platform based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Randomized or non-randomized clinical trials and observational studies evaluating the effectiveness of H. pylori infection rescue therapies were included. RESULTS: Twenty-eight studies were included in the analysis of mean eradication rates as rescue therapy, and 21 of these were selected for analysis of mean eradication rate as third-line treatment. For rifabutin-, sitafloxacin-, levofloxacin-, or metronidazole-based triple-therapy as third-line treatment, mean eradication rates of 81.6% and 84.4%, 79.4% and 81.5%, 55.7% and 60.6%, and 62.0% and 63.0% were found in intention-to-treat (ITT) and per-protocol (PP) analysis, respectively. For third-line quadruple therapy, mean eradication rates of 69.2% and 72.1% were found for bismuth quadruple therapy (BQT), 88.9% and 90.9% for bismuth quadruple therapy, three-in-one, Pylera® (BQT-Pylera), and 61.3% and 64.2% for non-BQT) in ITT and PP analysis, respectively. For rifabutin-, sitafloxacin-, levofloxacin-, or metronidazole-based triple therapy as rescue therapy, mean eradication rates of 75.4% and 78.8%, 79.4 and 81.5%, 55.7% and 60.6%, and 62.0% and 63.0% were found in ITT and PP analysis, respectively. For quadruple therapy as rescue treatment, mean eradication rates of 76.7% and 79.2% for BQT, 84.9% and 87.8% for BQT-Pylera, and 61.3% and 64.2% for non-BQT were found in ITT and PP analysis, respectively. For susceptibility-guided therapy, mean eradication rates as third-line and rescue treatment were 75.0% in ITT and 79.2% in PP analysis. CONCLUSION: We recommend sitafloxacin-based triple therapy containing vonoprazan in regions with low macrolide resistance profile. In regions with known resistance to macrolides or unavailability of bismuth, rifabutin-based triple therapy is recommended.

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BACKGROUND: Amoxicillin resistance in Helicobacter pylori is mainly associated with mutations in penicillin-binding protein-1A (PBP-1A). However, the specific amino acid substitutions in PBP-1A that confer amoxicillin resistance in H. pylori remain to be investigated. OBJECTIVE: This study aimed to investigate the molecular mechanism underlying amoxicillin resistance in patients with refractory H. pylori infection. METHODS: Esophagogastroduodenoscopy (EGD) was performed in patients with persistent H. pylori infection after at least two courses of H. pylori eradication therapy between January-2018 to March-2021. Refractory H. pylori was cultured from the gastric biopsy specimens. Antibiotic susceptibility testing was conducted to determine the minimum inhibitory concentrations (MICs). Sequence analysis of pbp-1A was performed for amoxicillin-resistant strains. RESULTS: Thirty-nine successfully cultured isolates were classified as refractory H. pylori isolates, and seventeen isolates were resistant to amoxicillin (MIC > 0.125 mg/L). Sequence analysis of resistant strains showed multiple mutations in the C-terminal region of PBP-1A that conferred amoxicillin resistance in H. pylori. However, the number of PBP-1A mutations did not correlate with the high MICs of amoxicillin-resistant isolates. Notably, some amino acid substitutions were identified in all Taiwanese isolates with history of eradication failure but not in published amoxicillin-susceptible strains, suggesting that the mutations may play a role in conferring antibiotic resistance to these strains. CONCLUSIONS: Our results show that amoxicillin resistance in refractory H. pylori is highly correlated with numerous PBP-1A mutations that are strain specific. Continuous improvements in diagnostic tools, particularly molecular analysis approaches, can help to optimize current antimicrobial regimens.

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The discovery of the pathological role of Helicobacter pylori in various disease states, such as peptic ulcer disease (PUD) and Mucosa Associated Lymphoid Tissue (MALT) lymphoma, was ground-breaking in the field of gastroenterology. Given the potentially dire clinical implications of chronic H. pylori infection, it is important to achieve complete eradication. More importantly, the rising prevalence of H. pylori antimicrobial resistance, similar to other pathogens world-wide, is of particular concern. Despite evidence supporting the growing threat of antimicrobial resistance, clinically, it is also important to survey just how much of the failed treatment is truly a reflection of resistance versus poor treatment adherence. In this report, we detail the case of a 64-year-old female who was previously given six treatment courses for persistent H. pylori infection. Successful eradication was achieved with rifabutin triple therapy consisting of high-dose amoxicillin and strict adherence monitoring by a clinical pharmacist. This case highlights the importance of patient education, medication reconciliation, and close monitoring to ensure successful treatment of persistent H. pylori infection.

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BACKGROUND: Rapid diagnosis and appropriate treatment of Munchausen syndrome is important not only for the patient but also for health care workers because a delay in diagnosis can worsen patients' clinical outcomes, and result in a substantial medical cost. CASE PRESENTATION: A young and previously healthy 24-year-old Japanese woman, a nurse, presented with complaints of refractory abscess on her left upper limb for 3 months. A physical examination on admission revealed low-grade fever and a subcutaneous abscess in her left forearm. Laboratory data suggested mild systemic inflammation and liver dysfunction, but no abnormalities of the immune system, including changes in the number of lymphocytes and neutrophils, neutrophil phagocytic capacity, and natural killer (NK) cell activity, were observed. A human immunodeficiency virus test was also negative. Multiple modalities, including positron emission tomography-computed tomography, failed to detect any cause and focus of infection except her left upper limb. Streptococcus mitis and Prevotella buccae were detected from the wound, but no microorganisms were detected in a blood culture. The cellulitis promptly resolved; however, exacerbation of the subcutaneous abscess with polymicrobial bacteremia repeatedly occurred unexpectedly. Because of this puzzling clinical course, the possibility of self-injury was finally suspected. Three syringes with needles, with a turbid liquid, were found in our patient's bag. Enterobacter cloacae and Enterococcus faecalis were detected in the liquid, and an analysis via repetitive element sequence-based polymerase chain reaction determined that Enterococcus faecalis in the wound and syringe contents were genetically identical. She was diagnosed as having Munchausen syndrome and treated with the collaboration of a psychiatrist. She finally confessed that she had injected her own saliva and toilet water into the drip line and wound. CONCLUSIONS: This case report is valuable in that it is the first case in which this syndrome was diagnosed by a genetic method. Munchausen syndrome should not be neglected as a possible cause of refractory and recurrent infection.

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OBJECTIVES: Failure of Helicobacter pylori eradication is documented in 20% of patients. Some patients show a negative faecal antigen test (FAT) with persistent symptoms after therapy. The aim of this study was to detect occult H. pylori infection in patients with persistent symptoms despite FAT negativity following therapy. METHODS: A total of 200 symptomatic patients presenting with dyspepsia and positive FAT were treated with H. pylori triple therapy for 2 weeks. Refractory patients received levofloxacin-based salvage therapy. Upper gastrointestinal endoscopy was performed for patients with persistent symptoms despite negative FAT after salvage therapy. Gastric biopsies were exposed to rapid urease test and RFLP-PCR for clarithromycin resistance in domain V of 23S rRNA (2142/2143 point mutations) as well as culture and antimicrobial susceptibility testing (AST). RESULTS: A total of 136 patients responded to classic triple therapy with negative FAT, and 15 patients showed persistent symptoms with positive FAT and received salvage therapy. The remaining 49 patients showed persistent symptoms despite negative FAT, therefore gastric biopsies with rapid urease test were performed. Clarithromycin resistance was confirmed in 12/49 patients (24.5%). Cultures were most commonly susceptible to norfloxacin (n=18), moxifloxacin (n=13), doxycycline (n=11) and amikacin (n=8). Non-responders with negative FAT had moderate or severe fatty liver disease (26.5% and 32.7%, respectively), 40.9% had hepatitis C virus (HCV) infection, and they had significantly higher HOMA-IR and HbA1c. CONCLUSION: Diabetes mellitus, HCV and non-alcoholic fatty liver disease predispose to refractory H. pylori requiring culture and AST.

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Neutropenic patients with hematological diseases are prone to severe infections. Granulocyte transfusion therapy (GTX) is considered as a logical therapeutic approach for these problems. However, the efficacy and complications of GTX have not been well identified. We retrospectively analyzed the clinical outcomes of GTX therapy in our hospital from 2009 to 2015. After 117 granulocyte transfusions for 47 patients, 72.3% of these patients' infections were effectively improved, and the overall survival rates at 30 and 120 days were 66.0 and 57.5%, respectively. The patients who experienced neutrophil recovery within 10 days after their therapy initiation had a better response and long-term survival period (14/15, 93.3%, vs 20/32, 62.5%, P = 0.037). Higher-dose granulocytes (> 2.55 × 108/kg) might improve the effective rate of infection in the patients who had more than 10 days neutrophil recovery time (17/23, 73.9%, vs 3/9, 33.3%, P = 0.049). In addition, GTX benefited the patients who suffered from pulmonary bacterial infections (16/20, 80%) compared with the bloodstream infection group (7/12, 58.3%) and skin or mucous infection group (1/5, 20%). The primary data showed that GTX did not affect the incidence of graft-versus-host disease (GVHD) and cytomegalovirus viremia when patients received further HSCT treatment. Collectively, GTX was an adjunct treatment modality for severely neutropenic patients who were likely to experience hematopoietic recovery. More randomized trials are needed to verify the efficacy and complications of GTX therapy.

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OBJECTIVES: In patients with very severe aplastic anemia (VSAA), neutropenia is prolonged and persistent, resulting in refractory overwhelming infections. Hematopoiesis recovery is urgently needed. METHODS: Six patients with de novo VSAA lacking HLA-identical sibling donors and those who experienced refractory infections underwent haploidentical related donor (HRD) hematopoietic stem cell transplantation (HSCT) as a first-line therapy. The conditioning regimen consisted of busulfan, cyclophosphamide, and rabbit antithymocyte globulin. Culture-expanded allogeneic bone marrow-derived mesenchymal stromal cells were infused on day 0 and day +14. RESULTS: From diagnosis to HSCT, 6 patients experienced a total of 28 episodes of persistent fever, and the median number was 4 (range, 3-7). All cases developed major bacterial infections and invasive pulmonary fungal infection pre-HSCT. The median time from diagnosis to HSCT was 2 months (range, 1-3.5 months). All patients achieved sustained, full donor chimerism, and the median time of myeloid recovery and platelet engraftment was 13 days (range, 9-19 days) and 15.5 days (range, 10-23 days), respectively. One patient died of aGVHD, and 5 patients are alive after a median follow-up of 21 months (range 17-40.5). CONCLUSIONS: Upfront HRD-HSCT may be a safe and promising choice for patients with VSAA in critical situations without suitably matched donors.

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