Persistent bacteremia caused by Ralstonia pickettii and Microbacterium: a case report.

BACKGROUND: Ralstonia pickettii is a low virulent, gram-negative bacillus that is rarely associated with human infections and may cause bacteremia. Microbacterium species are gram-positive coryneforms that are generally considered as a contaminant in Gram staining of blood cultures, especially when the time to positivity is longer than 48 h. Both these bacterial species are emerging opportunistic pathogens that may occasionally cause serious infections and even life-threatening health conditions. CASE PRESENTATION: Here, we report the case of a patient with bacteremia caused by both R. pickettii and Microbacterium. We advocate for providers to order rapid antibiotic susceptibility testing, since our patient's suffered two kinds of rare pathogens with the opposite of drug sensitivity results to imipenem. CONCLUSIONS: Our case present a patient suffered septic shock caused by R. pickettii and Microbacterium. Improving the antibiotic management based on the result of antimicrobial susceptibility tests is the key of successful treatment.

Bacterial peritonitis secondary to Capnocytophaga canimorsus.

We present the case of a patient with liver cirrhosis and several previous episodes of ascitic decompensation, who was admitted for bacterial peritonitis secondary to Capnocytophaga canimorsus infection. The initial clinical presentation, diagnosis, treatment and resolution are described. This is the first case described of peritonitis caused by this agent in a patient with similar characteristics.

Risk factors and outcome of Stenotrophomonas maltophilia infection after allogeneic hematopoietic stem cell transplantation: JSTCT, Transplant Complications Working Group.

Stenotrophomonas maltophilia (S. maltophilia) is an aerobic nonfermenting Gram-negative bacillus widely distributed in the environment that has inherent multidrug resistance to beta-lactam and carbapenem antibiotics. S. maltophilia infection (SMI) is known as an important fatal complication following allogeneic hematopoietic stem cell transplantation (HSCT), but its clinical characteristics have not been well clarified. A retrospective study to identify the incidence, risk factors, and outcomes of SMI after allogeneic HSCT was performed using the database of the Japanese nationwide registry, including 29,052 patients who received allogeneic HSCT in Japan between January 2007 and December 2016. A total of 665 patients developed SMI (sepsis/septic shock, 432; pneumonia, 171; other, 62). The cumulative incidence of SMI at 100 days after HSCT was 2.2%. Among risk factors identified for SMI (age ≥ 50 years, male, performance status 2-4, cord blood transplantation [CBT], myeloablative conditioning, Hematopoietic Cell Transplant-Comorbidity Index [HCT-CI] score 1-2, HCT-CI score ≥ 3, and active infectious disease at HSCT), CBT was the strongest risk factor (hazard ratio, 2.89; 95%CI, 1.94-4.32; p < 0.001). The survival rate at day 30 after SMI was 45.7%, and SMI before neutrophil engraftment was significantly associated with poor survival (survival rate 30 days after SMI, 40.1% and 53.8% in patients with SMI before and after engraftment, respectively; p = 0.002). SMI is rare after allogeneic HSCT, but its prognosis is extremely poor. CBT was a strong risk factor for SMI, and its development prior to neutrophil engraftment was associated with poor survival.

Gram-negative bacterial infection causes aggravated innate immune response in sepsis: Studies from clinical samples and cellular models.

Bacterial infection is the most common cause for sepsis. The purpose of this study was to evaluate the impact of different bacterial infection on sepsis based on human samples and cellular experiments. Physiological indexes and prognostic information of 121 sepsis patients were analysed based on whether they had a gram-positive or gram-negative bacterial infection. Moreover, murine RAW264.7 macrophages were treated with lipopolysaccharide (LPS) or peptidoglycan (PG) to simulate infection with gram-negative or gram-positive bacteria in sepsis, respectively. Exosomes derived from the macrophages were extracted for transcriptome sequencing. In patients with sepsis, most gram-positive bacterial infections were Staphylococcus aureus, and gram-negative infections were Escherichia coli. Gram-negative bacterial infection was significantly associated with high neutrophil and interleukin (IL)-6 levels in blood and shorter prothrombin (PT) and activated partial thromboplastin time (APTT). Intriguingly, the survival prognosis of sepsis patients was not affected by the type of bacterial infection, but it was significantly related to fibrinogen. Protein transcriptome sequencing of the macrophage-derived exosomes showed that differentially expressed proteins were significantly enriched in megakaryocyte differentiation, leukocyte and lymphocyte-mediated immunity, and complement and coagulation cascade pathways. The complement and coagulation-related proteins were significantly upregulated after LPS induction, which explained the shortened PT and APTT in gram-negative bacterial sepsis. Bacterial infection did not affect mortality in sepsis but did alter the host response. The immune disorder induced by gram-negative infection was more severe than that produced by gram-positive infection. This study provides references for the rapid identification and molecular research of different bacterial infections in sepsis.

Peritoneal dialysis-associated peritonitis presenting with Ralstonia pickettii infection: A novel series of three cases during the COVID-19 pandemic.

Peritoneal dialysis (PD)-associated peritonitis secondary to Ralstonia infection is very rare. Ralstonia pickettii is an organism that can grow in contaminated saline, water, chlorhexidine, and other medical products used in laboratories and the clinical setting. Infective endocarditis, prosthetic joint, and severe chest infections are previously reported with R. pickettii infection. We report a novel series of three cases diagnosed with PD-associated peritonitis caused by R. pickettii, where the cases appeared consecutively to our unit during a span of 4 weeks. During the COVID-19 pandemic, there were increased uses of non-sterile gloves by clinical staff as a form of personal protective equipment throughout patient interaction and PD exchange, as recommended by local hospital policy for all staff attending to patient care. A multidisciplinary team root cause analysis of our cases suggested non-sterile gloves being the likely source of environmental contamination, leading to PD-associated peritonitis caused by R. pickettii in this scenario.

Septic shock caused by Capnocytophaga canimorsus in a patient with heterozygous Pelger-Huët anomaly.

Capnocytophaga canimorsus is a Gram-negative bacillus of the commensal flora of dogs and cats that can cause infections in humans through bites, scratches or contact with oral secretions. It can be difficult to identify in clinical microbiology laboratories because of the need for specific culture media. We present the case of a patient with no relevant medical history who was admitted with septic shock, where blood smear examination was crucial for the etiologic diagnosis of Capnocytophaga canimorsus infection. The patient was also diagnosed Pelger-Huët anomaly, a condition causing a defect in neutrophil chemotaxis, which may have contributed to the severity of the infection.

Routine use of 16S rRNA PCR and subsequent sequencing from blood samples in septic shock: about two case reports of Capnocytophaga canimorsus infection in immunocompetent patients.

BACKGROUND: Capnocytophaga canimorsus infection happens frequently in immunosuppressed patients with reported domestic animal bites. Clinical presentation ranges from simple cellulitis to fulminant septic shock with disseminated intravascular coagulopathy, with an overall mortality of 30%. Conventional blood culture is often negative as this is a slow-growing pathogen. Nevertheless, the increasing use of 16S rRNA gene amplification and Sanger sequencing allows a much more rapid diagnostic confirmation. We present two case reports where 16S rRNA gene sequencing helped to diagnose Capnocytophaga canimorsus infection. CASE PRESENTATION: Case 1: A 53-year-old man with a history of non-cirrhotic chronic alcohol consumption was admitted to the intensive care unit (ICU) for septic shock and disseminated intravascular coagulopathy (DIC) of unknown origin. Blood cultures remained negative and a 16S rRNA PCR was performed leading to the identification of Capnocytophaga Canimorsus on day 4. Targeted antibiotic therapy with ceftriaxone for 14 days lead to overall recovery. Afterwards, the patient recalled a dog bite 2 days before hospitalization with a punctiform necrotic wound localized on a finger, which was not obvious at admission. Case 2: A 38-year-old man arrived to the emergency department for acute alcohol intoxication and history of a dog bite 2 days before. At admission, septic shock with purpura fulminans was diagnosed and required ICU hospitalization, invasive mechanical ventilation, vasopressor support and renal replacement therapy due to the rapid clinical deterioration. In the context of septic shock with purpura fulminans, DIC and recent dog bite, the diagnosis of Capnocytophaga canimorsus septic shock was suspected, and early confirmed by 16S rRNA PCR coupled to Sanger sequencing on day 2. Blood cultures became only positive for Capnocytophaga canimorsus 5 days after admission. Ceftriaxone alone was infused for 10 days in total, and the patient was discharged from the ICU on day 25. CONCLUSIONS: 16S rRNA gene PCR proves an important diagnostic tool when facing a sepsis of unknown origin. In these two cases of septic shock related to Capnocytophaga canimorsus, initial blood cultures remained negative at 24 h, whereas the diagnosis was achieved by 16S rRNA PCR sequencing performed from blood samples obtained at admission.

Diagnostic Value of Systemic Inflammatory Response Index for Catheter-Related Bloodstream Infection in Patients Undergoing Haemodialysis.

OBJECTIVE: This study was aimed at investigating the diagnostic value of the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), C-reactive protein-to-albumin ratio (CAR), and systemic inflammatory response index (SIRI) for catheter-related bloodstream infection (CRBSI) in patients undergoing haemodialysis. METHODS: A total of 296 patients undergoing haemodialysis with vascular access were selected and divided into the infected (58 patients) and uninfected (238 patients) groups. Their aetiological and general characteristics were retrospectively collected. The NLR, PLR, CAR, and SIRI were calculated. RESULTS: The NLR, PLR, CAR, and SIRI values in the infected group were significantly higher than those in the uninfected group (P < 0.05). After the anti-infective treatment, the NLR, PLR, CAR, and SIRI values in patients with CRBSI were significantly decreased (P < 0.05). The NLR, CAR, and SIRI showed diagnostic efficacy in patients with CRBSI with cut-off values of 4.485 (area under the curve (AUC) = 0.827, 95%confidence interval (CI) = 0.768-0.887), 0.975 (AUC = 0.836, 95%CI = 0.779-0.892), and 3.390 (AUC = 0.947, 95%CI = 0.919-0.976). The CAR and SIRI values in patients with gram-negative bacterial infection were significantly higher than those with gram-positive bacterial infection (P < 0.05). The AUCs of CAR and SIRI were 0.693 (0.537-0.848) and 0.821 (0.700-0.942) in differentiating gram-negative and gram-positive bacterial infections, respectively. CONCLUSION: Our results showed SIRI as a novel and efficient indicator for the early diagnosis of CRBSI in patients undergoing haemodialysis.

Population Pharmacokinetics and Dosing Optimization of Piperacillin-Tazobactam in Critically Ill Patients on Extracorporeal Membrane Oxygenation and the Influence of Concomitant Renal Replacement Therapy.

Critical illness and extracorporeal circulation, such as extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT), may alter the pharmacokinetics of piperacillin-tazobactam. We aimed to develop a population pharmacokinetic model of piperacillin-tazobactam in critically ill patients during ECMO or CRRT and investigate the optimal dosage regimen needed to achieve ≥90% of patients attaining the piperacillin pharmacodynamic target of 100% of dosage time above MIC of 16 mg/L. This prospective observational study included 26 ECMO patients, of which 13 patients received continuous venovenous hemodiafiltration (CVVHDF). A population pharmacokinetic model was developed using nonlinear mixed-effects models, and Monte Carlo simulations were performed to evaluate creatinine clearance (CrCL) and infusion method in relation to the probability of target attainment (PTA) in four patient groups according to combination of ECMO and CVVHDF. A total of 244 plasma samples were collected. In a two-compartment model, clearance decreased during ECMO and CVVHDF contributed to an increase in the volume of distribution. The range of PTA reduction as CrCL increased was greater in the order of intermittent bolus, extended infusion, and continuous infusion method. Continuous infusion should be considered in critically ill patients with CrCL of ≥60 mL/min, and at least 12, 16, and 20 g/day was required for CrCL of <40, 40 to 60, and 60 to 90 mL/min, respectively, regardless of ECMO or CVVHDF. In patients with CrCL of ≥90 mL/min, even a continuous infusion of 24 g/day was insufficient to achieve adequate PTA. Therefore, further research on permissible high continuous infusion dose focused on the risk of toxicity is required. (This trial has been registered at ClinicalTrials.gov under registration no. NCT02581280, December 1, 2014.) IMPORTANCE To the best of our knowledge, this is the first large prospective pharmacokinetic/pharmacodynamic (PK/PD) study of piperacillin-tazobactam in ECMO patients. We used piperacillin-tazobactam plasma concentration data from four different cases (concomitant use of ECMO and CVVHDF, receiving ECMO only, weaned from ECMO and receiving CVVHDF, and weaned from ECMO and not receiving CVVHDF) to provide preliminary insights into the incremental effects of critical illness, ECMO, and CVVHDF on PK. Our analysis revealed that volume of distribution increased in patients on CVVHDF and clearance decreased during ECMO and as creatinine clearance was reduced. When targeting 100% fT>MIC (16 mg/L, clinical breakpoint for Pseudomonas aeruginosa), continuous infusions would have achieved the highest percentage of target attainment compared to intermittent bolus or extended infusion if the total daily dose was the same. Continuous infusion should be considered in critically ill patients with creatinine clearance of ≥60 mL/min, regardless of ECMO or CVVHDF.

Ralstonia mannitolilytica sepsis after elective cesarean delivery: a case report.

BACKGROUND: Ralstonia mannitolilytica, a newly emerging opportunistic pathogen worldwide, has been reported to be responsible for human pneumonia, septicemia and meningitis. This is the first report of a case of Ralstonia mannitolilytica sepsis after elective cesarean delivery. CASE PRESENTATION: A 25-year-old woman, gravida 1 para 0, was scheduled for an elective cesarean delivery at 39+ 1 weeks of gestation. Sudden high fever and decreased blood pressure occurred a short time after the operation. Ralstonia mannitolilytica was identified in her blood culture 5 days after the operation. Based on the presence of sepsis and septic shock, massive fluid replacement, blood transfusion, vasoactive agents, imipenem/cilastatin and cefoperazone sulbactam sodium were applied. She was discharged after intensive care without complications. CONCLUSIONS: Although the incidence of sepsis due to Ralstonia mannitolilytica is relatively low, once infection occurs in a puerpera, severe symptoms develop abruptly. Thus, prompt diagnosis and appropriate treatment are key to the cure.

Peripheral Venous Catheter-related Bloodstream Infections in Hospitalized Children: The Role of Gram-negative Bacteria.

BACKGROUND: Peripheral venous catheter (PVC) is the most used vascular access device in medicine, allowing administration of intravenous fluids and medications. Known complications associated with PVC include extravasation, phlebitis and rarely bloodstream infection (BSI). Data regarding PVC-related BSI in children are lacking. Our aim was to evaluate the epidemiology, clinical and microbiologic characteristics of pediatric inpatients with PVC-related BSI. METHODS: A retrospective study was conducted in a pediatric tertiary care center. Children with BSI, admitted to general pediatric departments during 2010-2019, were identified and their medical records examined. Patients with BSI and phlebitis were further characterized and included in the analysis. We excluded patients with central venous catheters, other identified source of infection and with BSI upon admission. Data collected included patients' demographics and clinical and microbiologic characteristics. RESULTS: Twenty-seven children with PVC-related BSI were identified and included in the study, consisting of 0.2% of the total BSI cases. Patient's median age was 24 (range, 1.5-213) months, 14/27 (52%) were female and 6 (22%) were previously healthy while 21 (78%) had prior medical conditions. Sixteen (59.3%) patients had Gram-negative BSI and 6 (22.2%) Gram-positive bacteria. Polymicrobial infection occurred in 4 (14.8%) patients and Candida albicans in 1 (3.7%) patient. The most common isolated bacteria were Klebsiella spp and Staphylococcus aureus. Longer dwell-time was a predictor of Gram-negative bacteria. CONCLUSIONS: PVC-related BSI due to Gram-negative bacteria was more common than to Gram-positive bacteria. Clinicians should consider an initial broad-spectrum antibiotic coverage for PVC-related BSI in hospitalized pediatric patients.

Clinical and microbiological factors predicting outcomes of nonfermenting gram-negative bacilli peritonitis in peritoneal dialysis.

Peritonitis due to gram-negative bacilli (GNB), particularly nonfermenting GNB (NF-GNB), is a serious complication of peritoneal dialysis with a low resolution rate. Beyond the patient's condition, microbiological properties such as antimicrobial resistance, biofilm production and other virulence factors can explain the poor outcomes. This study aimed to evaluate the influence of patient condition, microbiological characteristics, including biofilm production, and treatment on peritonitis outcome. We reviewed the records of 62 index episodes caused by NF-GNB that occurred between 1997 and 2015 in our center. The etiologies were species of Pseudomonas (51.6%), Acinetobacter (32.2%), and other NF-GNB (16.1%). There was a high (72.9%) proportion of biofilm producer lineages. The in vitro susceptibility rate of Pseudomonas spp. to amikacin, ciprofloxacin, and ceftazidime was significantly greater than that of Acinetobacter spp. and other species; however, there was a similar low resolution rate (< 45%) among the episodes attributable to them. Preexisting exit-site infection was independently associated with nonresolution. No other factor, including biofilm production, was associated with the outcome. The higher in vitro susceptibility of Pseudomonas compared to other NF-GNB that presented a similar resolution rate suggests that bacterial virulence factors such as biofilms can act in concert, thereby worsening the outcome.

Impact of Donor-Derived Multi-drug-Resistant Organism Infections on Abdominal Solid Organ Transplantation Recipients in China.

BACKGROUND: Infection with multi-drug-resistant organisms (MDROs) is a life-threatening disease among abdominal solid organ transplantation recipients. Reports of donor-derived (DD) MDRO infections were few, but adverse clinical outcomes were severe, such as death or graft loss. METHODS: The medical records of 68 donation after citizens' death donors with MDRO infections and 20 recipients transmitted with infections between October 1, 2015, and September 1, 2020, were reviewed according to the Declaration of Helsinki and the Declaration of Istanbul. There were no grafts from prisoners, and no donors were not coerced or paid. RESULTS: Prevalence and mortality of DD-MDRO infection among abdominal solid organ transplantation recipients were 2.3% and 18.1%, respectively. The prevalence rate of DD-MDR gram-negative bacterial infection was higher than that of gram-positive bacterial infection (1.7% vs 0.6%). Negative culture of specimens occurred in 9 of 68 donors. Recipients with DD-MDR gram-negative bacterial infections had a significantly lower survival rate compared with DD-MDR gram-positive bacterial infections (P = .046). CONCLUSIONS: Donation after citizens' death donors and recipients had high MDRO infection rates, and gram-negative bacteria were the predominant pathogens. When a possible DD-MDRO infection occurs, there may be adverse outcomes with limited choice of antibiotics. A nationwide surveillance and communication network needs to be established in China.

Tunnelled hemodialysis catheter-related bloodstream infection with Ochrobactrum anthropi: a report of the first two cases from Bulgaria and a brief overview.

The use of central venous catheters for hemodialysis continues to grow worldwide, despite the efforts of many specialists. Patients with end-stage renal disease have impaired immunity, which is why infections are the most common complication seen in them. It worsens their quality of life and is a major cause of high morbidity and mortality, especially in hemodialysis patients.We report two cases of catheter-related bloodstream infection in hemodialysis patients caused by Ochrobactrum anthropi, which are the first reported cases in Bulgaria and present a brief literature review of the known facts.

First case report of Anaerobiospirillum succiniciproducens bacteremia in an HIV-infected patient in Taiwan - Molecular identification from a positive blood culture bottle.

Anaerobiospirillum succiniciproducens is a gram-negative, spiral-shaped anaerobe, that is a rare but potentially lethal cause of bacteremia in humans, particularly in immunocompromised hosts. We reported a 69-year-old HIV-infected male presenting with dysphagia, odynophagia and fulminant pneumonia who died. In addition, in a literature review, we summarized the characteristics of 19 adult patients with A. succiniciproducens bacteremia, which were confirmed by matrix-assisted laser desorption ionization-time of flight mass spectrometry or molecular methods. Among those, the presentation of gastrointestinal conditions was the only independent risk factor for mortality. Clinicians should be aware of this pathogen, especially when a culture is negative but a Gram stain reveals gram-negative spiral-shaped bacteria.

Stenotrophomonas maltophilia phenotypic and genotypic features through 4-year cystic fibrosis lung colonization.

Introduction. Stenotrophomonas maltophilia has emerged as one of the most common multi-drug-resistant pathogens isolated from people with cystic fibrosis (CF). However, its adaptation over time to CF lungs has not been fully established.Hypothesis. Sequential isolates of S. maltophilia from a Brazilian adult patient are clonally related and show a pattern of adaptation by loss of virulence factors.Aim. To investigate antimicrobial susceptibility, clonal relatedness, mutation frequency, quorum sensing (QS) and selected virulence factors in sequential S. maltophilia isolates from a Brazilian adult patient attending a CF referral centre in Buenos Aires, Argentina, between May 2014 and May 2018.Methodology. The antibiotic resistance of 11 S. maltophilia isolates recovered from expectorations of an adult female with CF was determined. Clonal relatedness, mutation frequency, QS variants (RpfC-RpfF), QS autoinducer (DSF) and virulence factors were investigated in eight viable isolates.Results. Seven S. maltophilia isolates were resistant to trimethoprim-sulfamethoxazole and five to levofloxacin. All isolates were susceptible to minocycline. Strong, weak and normomutators were detected, with a tendency to decreased mutation rate over time. XbaI PFGE revealed that seven isolates belong to two related clones. All isolates were RpfC-RpfF1 variants and DSF producers. Only two isolates produced weak biofilms, but none displayed swimming or twitching motility. Four isolates showed proteolytic activity and amplified stmPr1 and stmPr2 genes. Only the first three isolates were siderophore producers. Four isolates showed high resistance to oxidative stress, while the last four showed moderate resistance.Conclusion. The present study shows the long-time persistence of two related S. maltophilia clones in an adult female with CF. During the adaptation of the prevalent clones to the CF lungs over time, we identified a gradual loss of virulence factors that could be associated with the high amounts of DSF produced by the evolved isolates. Further, a decreased mutation rate was observed in the late isolates. The role of all these adaptations over time remains to be elucidated from a clinical perspective, probably focusing on the damage they can cause to CF lungs.

Optimal Antibiotic Duration for Bloodstream Infections Secondary to Intraabdominal Infection.

BACKGROUND: Bloodstream infections (BSIs) secondary to intraabdominal infections (IAIs) are common in the intensive care unit (ICU). The Surgical Infection Society guidelines recommend treatment duration after achieving source control in patients with secondary bacteremia; however, literature supporting this recommendation is limited. The purpose of this study was to compare outcomes in patients who received shorter versus extended duration of antibiotics for bacteremia secondary to IAI. MATERIALS AND METHODS: A retrospective cohort analysis was conducted in adult surgical ICU patients (n = 42) with BSIs and source control procedure(s) for IAI. The primary outcome was recurrent IAI. Secondary outcomes included surgical site infections (SSIs), Clostridium difficile infections (CDIs), secondary fungal infections, and in-hospital mortality. RESULTS: Forty-two patients met inclusion criteria and were divided into groups according to antimicrobial duration; 12 patients received <7 d, and 30 patients received >7 d of antibiotics. There were no differences in baseline characteristics between the two cohorts except for the presence of sepsis [4/12 (33.3%) versus 27/30 (90.0%); P = 0.001]. Thirty-one percent (13/42) of all organisms isolated from blood cultures were gram-negative bacteria, 12/42 (28.6%) were MDROs, and 2/42 (4.8%) patients experienced a culture mismatch in which cultured bacteria were not susceptible to empiric antibiotic therapy. Rates of recurrent IAI were similar between the two cohorts [1/12 (8.3%) versus 4/30 (13.3%), P = 0.554]. CONCLUSIONS: Among surgical ICU patients with BSI secondary to IAI, cessation of antibiotic therapy within 7 d of source control was not associated with an increased incidence of recurrent IAI.