Immunological Evaluation of Individuals Infected with Acinetobacter baumannii.

Acinetobacter baumannii (A. baumannii) is a spherical rod-shaped Gram-negative non-lactose fermenting (Coccobacilli, Aerobic bacteria) bacteria. It is a member of the Moraxellacea family. A. baumannii is a pathogenic, opportunistic organism that infects humans in society and hospitals. In particular, patients with immune system defects are at risk, especially those with burn infections and those hospitalized in intensive care (ICU). It plays a vital role in many illnesses, including septicemia, pneumonia, meningitis, soft tissues, skin infection, endocarditis, and urinary tract infection (UTI). The current study included immunological evaluation of infection with A. baumannii. In the current study, 150 blood samples were obtained as follows: 100 blood samples were collected from infected individuals with A. baumannii admitted to hospitals in Baghdad. Fifty blood samples were obtained from healthy individuals and considered as the control. 10 ml of blood samples were collected from the venous blood of the participants. A. baumannii was collected and isolated from infected patients and diagnosed by traditional methods, using different culture media (MacConkey agar, blood agar, and Chromogenetic agar) and by biochemical assays, then the bacteria diagnosis was confirmed using the VITEK 2 ID-GN cards. Microscopic examination and culture diagnosis of bacteria were conducted, and the diagnosis was confirmed by complete biochemical examinations using VITEK2 Compact System. Assessments included the serum level of IL-17A and TNF-α for hospitalized patients infected with A. baumannii. The study recorded a significant increase in the serum level of IL-17A for patients infected with A. baumannii (479.83±26.21 pg/ml) compared to control subjects (69.32±4.53 pg/ml). The recorded data showed a significant increase in the serum level of TNF-α for patients infected with A. baumannii (98.05±28.89 pg/ml) compared to control (1.40±25.12 pg/ml).

Risk Factors Associated With 30-Day Mortality Among Neonates With A. baumannii Sepsis.

BACKGROUND: Acinetobacter baumannii sepsis constitutes an extreme threat with a poor prognosis and is a difficult infection to control, especially in Asia. Moreover, a knowledge gap in the risk of mortality in neonatal A. baumannii sepsis still exists. METHODS: This study aimed to identify the risk factors of mortality in neonates with A. baumannii sepsis in Thailand from 1996 to 2019. A multivariable logistic regression model was analyzed for nonsurvivors and survivors of neonatal A. baumannii sepsis. RESULTS: In a 24-year period, 91 neonates with A. baumannii sepsis were reviewed. The median (interquartile range) gestational age and birth weight were 33 (28.5, 37.5) weeks and 1740 (987.5, 2730.0) g, respectively. The 30-day case fatality rate was 36.3% (33/91). In univariable analysis, nonsurvivors of neonatal A. baumannii sepsis was associated with smaller neonates, lower Apgar scores, septic shock, mechanical ventilation, umbilical catheterization, neutropenia, severe thrombocytopenia, carbapenem-resistant A. baumannii sepsis, inadequate empiric antimicrobial therapy, and acute kidney injury. In multivariable analysis, nonsurvivors of neonatal A. baumannii sepsis were associated with septic shock (adjusted odds ratio [OR] = 41.38; 95% confidence intervals [CI]: 3.42-501.13; P = 0.003), severe thrombocytopenia (adjusted OR = 33.70; 95% CI: 3.44-330.55; P = 0.002), and inadequate empiric antimicrobial therapy (adjusted OR = 10.05; 95% CI: 1.40-71.98; P = 0.02). CONCLUSION: In high multidrug-resistant areas, empiric treatment with broader spectrum antimicrobials should be considered in neonates with sepsis shock or severe thrombocytopenia.

Monoclonal Antibody Therapy against Acinetobacter baumannii.

Extremely drug-resistant (XDR) Acinetobacter baumannii is a notorious and frequently encountered pathogen demanding novel therapeutic interventions. An initial monoclonal antibody (MAb), C8, raised against A. baumannii capsule, proved a highly effective treatment against a minority of clinical isolates. To overcome this limitation, we broadened coverage by developing a second antibody for use in a combination regimen. We sought to develop an additional anti-A. baumannii MAb through hybridoma technology by immunizing mice with sublethal inocula of virulent, XDR clinical isolates not bound by MAb C8. We identified a new antibacterial MAb, 65, which bound to strains in a pattern distinct from and complementary to that of MAb C8. MAb 65 enhanced macrophage opsonophagocytosis of targeted strains and markedly improved survival in lethal bacteremic sepsis and aspiration pneumonia murine models of A. baumannii infection. MAb 65 was also synergistic with colistin, substantially enhancing protection compared to monotherapy. Treatment with MAb 65 significantly reduced blood bacterial density, ameliorated cytokine production (interleukin-1ß [IL-1ß], IL-6, IL-10, and tumor necrosis factor), and sepsis biomarkers. We describe a novel MAb targeting A. baumannii that broadens immunotherapeutic strain coverage, is highly potent and effective, and synergistically improves outcomes in combination with antibiotics.

A Multiepitope Peptide, rOmp22, Encapsulated in Chitosan-PLGA Nanoparticles as a Candidate Vaccine Against Acinetobacter baumannii Infection.

BACKGROUND: The development of vaccines is a promising and cost-effective strategy to prevent emerging multidrug-resistant (MDR) Acinetobacter baumannii (A. baumannii) infections. The purpose of this study was to prepare a multiepitope peptide nanovaccine and evaluate its immunogenicity and protective effect in BALB/c mice. METHODS: The B-cell and T-cell epitopes of Omp22 from A. baumannii were predicted using bioinformatics methods and identified by immunological experiments. The optimal epitopes were conjugated in series by 6-aminocaproic acid and chemically synthesized multiepitope polypeptide rOmp22. Then, rOmp22 was encapsulated by chitosan (CS) and poly (lactic-co-glycolic) acid (PLGA) to prepare CS-PLGA-rOmp22 nanoparticles (NPs). The immunogenicity and immunoprotective efficacy of the vaccine were evaluated in BALB/c mice. RESULTS: CS-PLGA-rOmp22 NPs were small (mean size of 272.83 nm) with apparently spherical structures, positively charged (4.39 mV) and nontoxic to A549 cells. A high encapsulation efficiency (54.94%) and a continuous slow release pattern were achieved. Compared with nonencapsulated rOmp22, CS-PLGA-rOmp22 immunized BALB/c mice induced higher levels of rOmp22-specific IgG in serum and IFN-γ in splenocyte supernatant. Additionally, lung injury and bacterial burdens in the lung and blood were suppressed, and potent protection (57.14%-83.3%) against acute lethal intratracheal A. baumannii challenge was observed in BALB/c mice vaccinated with CS-PLGA-rOmp22. CONCLUSION: CS-PLGA-rOmp22 NPs elicited specific IgG antibodies, Th1 cellular immunity and protection against acute lethal intratracheal A. baumannii challenge. Our results indicate that this nanovaccine is a desirable candidate for preventing A. baumannii infection.

Analysis of virulence phenotypes and antibiotic resistance in clinical strains of Acinetobacter baumannii isolated in Nashville, Tennessee.

BACKGROUND: Acinetobacter baumannii is a gram-negative bacterium which causes opportunistic infections in immunocompromised hosts. Genome plasticity has given rise to a wide range of strain variation with respect to antimicrobial resistance profiles and expression of virulence factors which lead to altered phenotypes associated with pathogenesis. The purpose of this study was to analyze clinical strains of A. baumannii for phenotypic variation that might correlate with virulence phenotypes, antimicrobial resistance patterns, or strain isolation source. We hypothesized that individual strain virulence phenotypes might be associated with anatomical site of isolation or alterations in susceptibility to antimicrobial interventions. METHODOLOGY: A cohort of 17 clinical isolates of A. baumannii isolated from diverse anatomical sites were evaluated to ascertain phenotypic patterns including biofilm formation, hemolysis, motility, and antimicrobial resistance. Antibiotic susceptibility/resistance to ampicillin-sulbactam, amikacin, ceftriaxone, ceftazidime, cefotaxime, ciprofloxacin, cefepime, gentamicin, levofloxacin, meropenem, piperacillin, trimethoprim-sulfamethoxazole, ticarcillin- K clavulanate, tetracyclin, and tobramycin was determined. RESULTS: Antibiotic resistance was prevalent in many strains including resistance to ampicillin-sulbactam, amikacin, ceftriaxone, ceftazidime, cefotaxime, ciprofloxacin, cefepime, gentamicin, levofloxacin, meropenem, piperacillin, trimethoprim-sulfamethoxazole, ticarcillin- K clavulanate, tetracyclin, and tobramycin. All strains tested induced hemolysis on agar plate detection assays. Wound-isolated strains of A. baumannii exhibited higher motility than strains isolated from blood, urine or Foley catheter, or sputum/bronchial wash. A. baumannii strains isolated from patient blood samples formed significantly more biofilm than isolates from wounds, sputum or bronchial wash samples. An inverse relationship between motility and biofilm formation was observed in the cohort of 17 clinical isolates of A. baumannii tested in this study. Motility was also inversely correlated with induction of hemolysis. An inverse correlation was observed between hemolysis and resistance to ticarcillin-k clavulanate, meropenem, and piperacillin. An inverse correlation was also observed between motility and resistance to ampicillin-sulbactam, ceftriaxone, ceftoxamine, ceftazidime, ciprofloxacin, or levofloxacin. CONCLUSIONS: Strain dependent variations in biofilm and motility are associated with anatomical site of isolation. Biofilm and hemolysis production both have an inverse association with motility in the cohort of strains utilized in this study, and motility and hemolysis were inversely correlated with resistance to numerous antibiotics.

Virulence role of the outer membrane protein CarO in carbapenem-resistant Acinetobacter baumannii.

Novel approaches to treat carbapenem-resistant Acinetobacter baumannii (CRAB) infections are urgently needed and anti-virulence drugs represent promising alternatives, but our knowledge on potential targets is scarce. We searched for potential A. baumannii virulence factors by whole-genome sequencing-based comparisons of CRAB clinical isolates causing bloodstream infections secondary to ventilator-associated pneumonia from demographics and clinically homogeneous patients, who received optimal treatment but with different clinical outcomes. Thus, the carO gene was interrupted in CRAB isolates from surviving patients, while it was intact in isolates from non-surviving patients, and proteomic/immunoblot techniques corroborated it. When the virulence role of A. baumannii CarO was analyzed in model systems, isogenic ΔcarO mutants and a CRAB clinical isolate with truncated CarO, showed lower ability to adhere and invade A549 cells and in vivo virulence. This unnoticed virulence role for CarO postulate this A. baumannii outer membrane protein as a potential target for new therapies against CRAB infections.

CsrA Supports both Environmental Persistence and Host-Associated Growth of Acinetobacter baumannii.

Acinetobacter baumannii is an opportunistic and frequently multidrug-resistant Gram-negative bacterial pathogen that primarily infects critically ill individuals. Indirect transmission from patient to patient in hospitals can drive infections, supported by this organism's abilities to persist on dry surfaces and rapidly colonize susceptible individuals. To investigate how A. baumannii survives on surfaces, we cultured A. baumannii in liquid media for several days and then analyzed isolates that lost the ability to survive drying. One of these isolates carried a mutation that affected the gene encoding the carbon storage regulator CsrA. As we began to examine the role of CsrA in A. baumannii, we observed that the growth of ΔcsrA mutant strains was inhibited in the presence of amino acids. The ΔcsrA mutant strains had a reduced ability to survive drying and to form biofilms but an improved ability to tolerate increased osmolarity compared with the wild type. We also examined the importance of CsrA for A. baumannii virulence. The ΔcsrA mutant strains had a greatly reduced ability to kill Galleria mellonella larvae, could not replicate in G. mellonella hemolymph, and also had a growth defect in human serum. Together, these results show that CsrA is essential for the growth of A. baumannii on host-derived substrates and is involved in desiccation tolerance, implying that CsrA controls key functions involved in the transmission of A. baumannii in hospitals.

Pathogenic spectrum of blood stream infections and resistance pattern in Gram-negative bacteria from Aljouf region of Saudi Arabia.

BACKGROUND: The pathogenic spectrum of bloodstream infections (BSIs) varies across regions. Monitoring the pathogenic profile and antimicrobial resistance is a prerequisite for effective therapy, infection control and for strategies aimed to counter antimicrobial resistance. The pathogenic spectrum of BSIs in blood cultures was analysed, focusing on the resistance patterns of Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae, in Aljouf region. METHODS: This descriptive cross-sectional study analysed the culture reports of all non-duplicate blood samples collected from January 1 to December 31, 2019. Antibiograms of A. baumannii, E. coli, and K. pneumoniae were analysed for antibiotic resistance. The frequency and percentages of multi-drug, extensively-drug, pan-drug and carbapenem resistance were calculated. RESULTS: Of the 222 bloodstream infections, 62.2% and 36.4% were caused by gram-negative and gram-positive bacteria, respectively. Most BSIs occurred in patients aged ≥60 years (59.5%). Among the 103 isolates of the studied Gram-negative bacteria (GNB), 47.6%, 38.8%, and 2.9% were multi-drug, extensively drug and pan-drug resistant respectively. 46% of K. pneumoniae isolates were carbapenemase producers. Resistance to gentamycin, 1st-4th generation cephalosporins, and carbapenems was observed for A. baumannii. More than 70% of E. coli isolates were resistant to 3rd- and 4th-generation cephalosporins. Klebsiella pneumoniae presented a resistance rate of >60% to imipenems. CONCLUSIONS: Gram-negative bacteria dominate BSIs, with carbapenem-resistant K. pneumoniae most frequently detected in this region. Resistant GNB infections make it challenging to treat geriatric patients. Regional variations in antimicrobial resistance should be continually monitored.

Elevated serum procalcitonin predicts Gram-negative bloodstream infections in patients with burns.

BACKGROUND: Many studies have suggested that procalcitonin can predict bloodstream infection and also distinguish between Gram-negative, Gram-positive and fungal infections after burn. However, up to now, there is no literature on serum procalcitonin level of multidrug-resistant pathogens and non-multidrug-resistant pathogens among Gram-negative bloodstream infections after burn. The purpose of this study is to explore the value of serum procalcitonin in identifying Gram-negative bloodstream infection in patients with febrile critical burn and then to investigate the difference of serum procalcitonin level between multidrug-resistant pathogens and non-multidrug-resistant pathogens among Gram-negative bloodstream infections after burn. METHODS: Patients with febrile critical burn admitted to the burn department of our hospital from 1 January 2014 to 1 August 2018 were retrospectively analysed. Patients with positive blood culture whose blood samples were collected for simultaneous blood culture and procalcitonin testing were enrolled. All strains were identified by an automatic microorganism analyser, and procalcitonin was analysed by an automatic electrochemiluminescence immunoassay. RESULTS: Overall, a total of 119 patients with positive blood culture met the inclusion criteria. There were 64 Gram-negative bacilli, 38 Gram-positive bacteria, 8 C. albicans and 9 polymicrobial bloodstream infections. The median procalcitonin value in Gram-negative bloodstream infections (2.67 ng/mL, interquartile range (IQR) 1.58-6.08) was significantly higher than that in Gram-positive bloodstream infections (1.04 ng/mL, IQR 0.35-1.60, P < 0.01), or C. albicans bloodstream infections (1.09 ng/mL, IQR 0.82-2.30, P < 0.05). Receiver operating characteristic curve (ROC) analysis showed that in addition to polymicrobial bloodstream infections, the area of procalcitonin under the curve distinguishing Gram-negative bloodstream infections from all other blood culture-positive bloodstream infections was 0.761, the best critical value was 1.73 ng/mL, the sensitivity was 73%, the specificity was 74%, the positive predictive value was 80%, the negative predictive value was 67%, The level of procalcitonin was significantly higher in multidrug-resistant Gram-negative bacilli (A. baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa) (2.76 ng/mL, IQR 2.01-7.76) than in non-multidrug-resistant bacilli (1.01 ng/mL, IQR 0.58-1.56, P < 0.01). CONCLUSION: Elevated serum procalcitonin can identify Gram-negative bloodstream infections in patients with febrile critical burn. In Gram-negative bloodstream infections, high procalcitonin levels may be associated with multidrug-resistant Gram-negative bacilli (A. baumannii, K. pneumoniae and P. aeruginosa).

Sepsis 2019: What Surgeons Need to Know.

The definition of sepsis continues to be as dynamic as the management strategies used to treat this. Sepsis-3 has replaced the earlier systemic inflammatory response syndrome (SIRS)-based diagnoses with the rapid Sequential Organ Failure Assessment (SOFA) score assisting in predicting overall prognosis with regards to mortality. Surgeons have an important role in ensuring adequate source control while recognizing the threat of carbapenem-resistance in gram-negative organisms. Rapid diagnostic tests are being used increasingly for the early identification of multi-drug-resistant organisms (MDROs), with a key emphasis on the multidisciplinary alert of results. Novel, higher generation antibiotic agents have been developed for resistance in ESKCAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) organisms while surgeons have an important role in the prevention of spread. The Study to Optimize Peritoneal Infection Therapy (STOP-IT) trial has challenged the previous paradigm of length of antibiotic treatment whereas biomarkers such as procalcitonin are playing a prominent role in individualizing therapy. Several novel therapies for refractory septic shock, while still investigational, are gaining prominence rapidly (such as vitamin C) whereas others await further clinical trials. Management strategies presented as care bundles continue to be updated by the Surviving Sepsis Campaign, yet still remain controversial in its global adoption. We have broadened our temporal and epidemiologic perspective of sepsis by understanding it both as an acute, time-sensitive, life-threatening illness to a chronic condition that increases the risk of mortality up to five years post-discharge. Artificial intelligence, machine learning, and bedside scoring systems can assist the clinician in predicting post-operative sepsis. The public health role of the surgeon is key. This includes collaboration and multi-disciplinary antibiotic stewardship at a hospital level. It also requires controlling pharmaceutical sales and the unregulated dispensing of antibiotic agents globally through policy initiatives to control emerging resistance through prevention.

Diabetic status and the relationship of blood glucose to mortality in adults with carbapenem-resistant Acinetobacter baumannii complex bacteremia.

BACKGROUND/PURPOSE: Diabetes is associated with increased mortality in Acinetobacter baumannii (AB) complex infection. This study investigated the risk factors and relationship of diabetic status and glycemic indices to mortality in patients with carbapenem-resistant (CR) AB complex bacteremia. METHODS: Relationship of glycemic indices to mortality were compared in adult diabetes (DM) and nondiabetes (non-DM) patients with CRAB complex bacteremia hospitalized from January 2010 to December 2015 in MacKay Memorial Hospital, Taiwan. RESULTS: Of 317 patients with CRAB complex bacteremia, 146 (46.06%) had diabetes. DM patients were elderly (mean age of 69.23 years) and the mortality rate was higher (64.38% vs. 52.05%, p = 0.036) than in non-DM patients. By multivariate analysis, septic shock was associated with increased mortality in DM patients. Hypoglycemia was associated with increased mortality in non-DM patients only (100% vs. 50.33%, p = 0.006). The lowest mortality was for the blood glucose range 70-100 mg/dL in non-DM patients (43.24%) and 100-140 mg/dL for DM patients (56.52%). Increased glycemic variability (coefficient of variation (CV) > 40% compared to < 20%) was associated with increased mortality in non-DM patients (86.36% vs. 47.12%, p = 0.003). CONCLUSION: Effects of dysglycemia on mortality due to CRAB complex bacteremia differ according to diabetic status. Mortality was higher in DM patients. In non-DM patients, hypoglycemia and increased CV were associated with increased mortality. The lowest mortality was for the blood glucose range 70-100 mg/dL in non-DM patients and 100-140 mg/dL for DM patients.

Control of Acinetobacter baumannii outbreak in the neonatal intensive care unit in Latvia: whole-genome sequencing powered investigation and closure of the ward.

Background: Acinetobacter baumannii is an emerging pathogen capable of causing hospital-acquired infections (HAIs). It has the ability to survive on environmental surfaces for months, making transmission difficult to control. Our report describes the investigation and restriction of an outbreak of A.baumannii in the Neonatal Intensive Care Unit (NICU) using whole-genome sequencing (WGS) and multi-modal infection control measures. Methods: A prospective surveillance of HAIs was initiated in the NICU at the Pauls Stradins Clinical University Hospital (PSCUH) in Latvia on 1/9/2012 and identified an outbreak of A.baumannii. Case definitions for A.baumannii bloodstream infection (BSI) and colonization were implemented; surveillance cultures were obtained from all admitted patients to monitor the rate of colonization; an infection prevention and control team was formed and infection control interventions implemented. Environmental sampling of the NICU and Labour ward was performed. We employed WGS to differentiate phenotypically identical multidrug-resistant A.baumannii (MDRAB) strains from simultaneous intrahospital outbreaks in the adult Intensive Care Unit and NICU. Results: Between 1/9/2012 and 31/12/2017 the surveillance included 2157 neonates. A total of 17 neonates had A.baumannii BSI, with the highest rate of 30.0 cases per 1000 bed-days in November 2012. Rectal screening samples were positive for A.baumannii-complex in 182 neonates reaching 119.6 per 1000 bed-days in July 2015. All 298 environmental cultures were negative. Two phenotypically identical MDRAB isolates from the simultaneous intrahospital outbreaks were differentiated using WGS, ruling out an inter-ward transmission. Adherence to stringent infection control measures decreased BSI cases but colonization remained persistent. With several relapses, the outbreak was ongoing for four years. No new A.baumannii BSI cases were registered after total environmental decontamination in the NICU in July 2015. Colonization reappeared and persisted until in November 2016 when the ward was temporarily closed, relocated and renovated. No A.baumannii cases were registered after the renovation. Conclusion: The HAI surveillance system successfully detected and facilitated the control of the A.baumannii outbreak. Whole-genome sequencing was found to be a useful method for differentiation of phenotypically identical A.baumannii strains from the intrahospital outbreak. Only multi-modal infection control program, including closure, temporary relocation, and renovation of the ward, restricted the outbreak.

A Case-Control Study: Clinical Characteristics of Nosocomial Bloodstream Infections Versus Non-bloodstream Infections of Acinetobacter spp.

Background: Acinetobacter spp. are among the most common causes of bacterial nosocomial infections, including pneumonia and bloodstream infections. Previous studies on the risk factors of bloodstream Acinetobacter spp. infections (BSAcIs) primarily compared uninfected patients to those with BSAcIs. However, the identified risk factors contribute to either BSIs or Acinetobacter spp. infections. To the best of our knowledge, this is the first study to analyze the risk factors of BSAcIs in comparison to non-bloodstream Acinetobacter infections (non-BSAcIs). Methods: We retrospectively reviewed 10 years of medical records of BSAcIs from a teaching hospital in Shanghai. Clinical characteristics and treatment outcomes were compared between BSAcIs and non-BSAcIs. Treatment outcomes of carbapenem- and sulbactam-based regimens were also evaluated. Results: Respiratory tract infections (43.1%, 44/102) were the most common source of BSAcIs. The in-hospital mortality rate of BSAcIs (22.5%, 23/102) was significantly higher than that of non-BSAcIs (10.8%, 24/204). Compared with non-BSAcIs, the previous use of corticoids, proton pump inhibitor (PPI) usage, and the implementation of intracranial drainage were independent risk factors for BSAcIs. The clinical efficacy rate of antimicrobial treatment of carbapenem-susceptible BSAcIs was significantly higher than that of carbapenem-non-susceptible (CNS) BSAcIs (74.0% vs 44.3%). Sulbactam-based regimens had similar clinical efficacy rates as carbapenem-based regimens for treating CNS-BSAcIs (50.0% vs 45.8%). Conclusions: The in-hospital mortality rate of BSAcIs was significantly higher than that of non-BSAcIs. Glucocorticoids, PPI usage, and intracranial drainage were independent risk factors for BSAcIs. Sulbactam-based regimens had similar clinical efficacy rates as carbapenem-based regimens for treating CNS-BSAcIs.

Exploring a phage-based real-time PCR assay for diagnosing Acinetobacter baumannii bloodstream infections with high sensitivity.

In the present study, we developed a phage-based real-time quantitative PCR (qPCR) methodology for sensitive diagnosis of bloodstream infection (BSI) caused by Acinetobacter baumannii (A. baumannii). An isolated A. baumannii phage p53 was used for Taqman qPCR through detecting phage replication in live A. baumannii cells in serum samples. At the phage concentration of 103 PFU/mL, the sensitive detection of A. baumannii (down to 10 CFU in 100 µL serum) has been obtained within 4 h in spiked serum samples without bacteria isolation and DNA extraction. Subsequent testing of 22 simulated serum samples spiked by different strains has shown that the results from the phage-based Taqman qPCR method have 100% agreement with the spiked concentrations of the bacteria. The assay built in this study, gathering all the advantages for detections of high rapidity, high sensitivity, good specificity, being able to detect only live bacteria not dead bacteria and no DNA extraction or purifications, can be developed to detecting other bacterial pathogens in serum or other complicated samples through switching to other types of phages and realize the rapid and sensitive detection of bacteria in BSI, which would potentially be applied for fast diagnosis in sepsis clinically.

Plasma and Intrapulmonary Concentrations of ETX2514 and Sulbactam following Intravenous Administration of ETX2514SUL to Healthy Adult Subjects.

ETX2514 is a novel ß-lactamase inhibitor that broadly inhibits Ambler class A, C, and D ß-lactamases. ETX2514 combined with sulbactam (SUL) in vitro restores sulbactam activity against Acinetobacter baumannii ETX2514-sulbactam (ETX2514SUL) is under development for the treatment of A. baumannii infections. The objective of this study was to determine and compare plasma, epithelial lining fluid (ELF), and alveolar macrophage (AM) concentrations following intravenous (i.v.) ETX2514 and sulbactam. Plasma, ELF, and AM concentrations of ETX2514 and sulbactam were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in 30 healthy adult subjects following repeated dosing (ETX2514 [1 g] and sulbactam [1 g] every 6 h [q6h], as a 3-h i.v. infusion, for a total of 3 doses). A bronchoalveolar lavage (BAL) was performed once in each subject at either 1, 2.5, 3.25, 4, or 6 h after the start of the last infusion. Penetration ratios were calculated from area under the concentration-time curve from 0 to 6 h (AUC0-6) values for total plasma and ELF using mean and median concentrations at the BAL fluid sampling times. Respective ELF AUC0-6 values, based on mean and median concentrations, were 40.1 and 39.4 mg · h/liter for ETX2514 and 34.7 and 34.5 mg · h/liter for sulbactam. Respective penetration ratios of ELF to total/unbound plasma concentrations, based on mean and median AUC0-6 values, of ETX2514 were 0.37/0.41 and 0.36/0.40, whereas these same ratio values were 0.50/0.81 and 0.50/0.80 for sulbactam. ETX2514 and sulbactam concentrations in AM were measurable and fairly constant throughout the dosing interval (median values of 1.31 and 1.01 mg/liter, respectively). These data support further study of ETX2514SUL for the treatment of pneumonia caused by multidrug-resistant A. baumannii (This study has been registered at ClinicalTrials.gov under identifier NCT03303924.).

Identification of Acinetobacter seifertii isolated from Bolivian hospitals.

Acinetobacter seifertii is a recently described species that belongs to the Acinetobacter calcoaceticus-Acinetobacter baumannii complex. It has been recovered from clinical samples and is sometimes associated with antimicrobial resistance determinants. We present here the case of three A. seifertii clinical isolates which were initially identified as Acinetobacter sp. by phenotypic methods but no identification at the species level was achieved using semi-automated identification methods. The isolates were further analysed by whole genome sequencing and identified as A. seifertii. Due to the fact that A. seifertii has been isolated from serious infections such as respiratory tract and bloodstream infections, we emphasize the importance of correctly identifying isolates of the genus Acinetobacter at the species level to gain a deeper knowledge of their prevalence and clinical impact.

High Prevalence of Extensively Drug-resistant Acinetobacter baumannii at a Children Hospital in Bolivia.

Acinetobacter baumannii causes serious hospital-acquired infections and has been positioned as a priority organism by the World Health Organization. This study includes 36 A. baumannii isolates from a children hospital recovered between March 2014 and May 2015 in Cochabamba. The majority of the isolates were recovered from blood cultures (n = 10, 31.3%) and respiratory samples (n = 11, 34.4%); 53% of the patients were younger than 1 month old. Most of these isolates (n = 30, 80.6%) were extremely drug resistant and 8.3% were multidrug resistant. The circulation of 2 predominant clones including 25 isolates was determined by pulsed-field gel electrophoresis; 9 of the isolates were considered sporadic strains. The isolates grouped in the predominant clones and 5 of the unrelated sporadic strains were single-locus variant or double locus variant of clonal complex (CC110), belonging to international clone 7; the rest of the isolates were single-locus variant or double locus variant of another clonal complex. All the carbapenem-resistant isolates (88.9%) carried the blaOXA-23-like in a similar structure to Tn2008 located on the chromosome, and the aac(3)-IIa gene was present in all the aminoglycoside-resistant isolates (86.1%). Strong biofilm producers were found among these isolates, being the strongest ones those recovered from the hospital environment, catheter, blood and cerebrospinal fluid (CSF) all of them belonged to the unrelated sporadic strains. The present study demonstrated the predominance and spread of closely related extremely drug-resistant A. baumannii isolates, what confers increasing risk to children and is of major concern because of the kind of infections and the lack of therapeutic alternatives to treat them.

Extensively drug-resistant Acinetobacter baumannii bacteraemia in a multidisciplinary intensive care unit during a 6-year period: Risk factors for fulminant sepsis.

OBJECTIVES: This study aimed to determine potential host-, pathogen-, infection- and treatment-related risk factors that might predict a fulminant fatal course of bacteraemia caused by extensively drug-resistant Acinetobacter baumannii (XDR-Aba). METHODS: Eighty-seven patients with monomicrobial growth of XDR-Aba in blood cultures within a 6-year period (2011-2016) were studied. Patients were divided into three groups according to ICU outcome: Group A (n=40) consisted of patients who survived; Group B (n=10) included patients with fulminant sepsis who died early (≤48h); and Group C (n=37) included patients who died later (>48h) after the onset of bacteraemia. RESULTS: Regarding patient co-morbidities, patients who died from fulminant XDR-Aba bacteraemia had a significantly higher prevalence of chronic renal failure compared with patients who survived (40.0% vs. 7.5%; P=0.029). Patients with fulminant sepsis showed more severe organ dysfunction based on SOFA score compared with survivors (10.83±2.93 vs. 6.65±3.6; P=0.013). The primary to secondary bacteraemia ratio and appropriate treatment were similar among the three outcome groups. Patients with fulminant bacteraemia displayed higher rates of colistin-, tigecycline- and pandrug-resistant strains, although not statistically significant. CONCLUSIONS: Patients suffering from a fulminant course of XDR-Aba bacteraemia showed significantly higher rates of chronic renal failure and multiple organ dysfunction. Resistance patterns of XDR-Aba isolates and receipt of appropriate treatment did not affect outcomes. Further studies including larger samples of patients along with investigation of specific virulence determinants of individual Aba strains are needed.

[Establishment of Acinetobacter baumannii-induced pneumonia model in mice].

Objective To establish Acinetobacter baumannii (A. baumannii)-induced pneumonia models in C57BL/6 mice, and study the molecule mechanism of A. baumannii infection. Methods Eighty C57BL/6 mice were divided into normal control group, cyclophosphamide-treated group, A. baumannii infection group, and cyclophosphamide-pretreated A. baumannii infection group. Immunodeficient mice were prepared by injecting cyclophosphamide intraperitoneally. A. baumannii was isolated from intensive care unit (ICU) and fresh bacteria (1×108 CFU/mL) were prepared. Each normal or immunodeficient mouse was inoculated with 50 µL A. baumannii through trachea. The lung, bronchoalveolar lavage fluid (BALF) and blood were collected at 6, 24 and 72 hours after inoculation. The numbers of white blood cells (WBCs) and neutrophils were detected by cell counting. The histopathology of the lung was evaluated by HE staining. Cytokines such as granulocyte macrophage colony-stimulating factor (GM-CSF), interferon γ (IFN-γ), interleukin 1ß (IL-1ß), IL-2, IL-4, IL-5, IL-6, IL-10, IL-12, tumor necrosis factor α (TNF-α) were detected by ELISA. Results A. baumannii was eliminated within 72 hours after infection in normal mice, whereas the bacteria continued to replicate rapidly in the lungs and blood in the immunodeficient mice. The numbers of WBCs and neutrophils were elevated markedly 6 hours post infection, and return to the normal within 72 hours. However, the numbers of WBCs and neutrophils continuously increased in cyclophosphamide-pretreated A. baumannii infection group, and the pulmonary inflammatory was more severe than that in the normal mice. The cytokines of blood increased markedly 6 hours post infection, and then decreased until 72 hours. However, the cytokines continuously increased in cyclophosphamide-pretreated A. baumannii infection group. Conclusion A. baumannii-induced pneumonia models in C57BL/6 mice were established successfully.