Carbapenem-resistant versus carbapenem-susceptible Acinetobacter baumannii bacteremia in a Greek intensive care unit: risk factors, clinical features and outcomes

Nosocomial, Healthcare-Associated, and Community-Acquired Acinetobacter baumannii in China: Clinical Characteristics, Antimicrobial Resistance Patterns and Risk Factors Associated with Carbapenem Resistance

Background

Acinetobacter baumannii (A. baumannii) is an widespread pathogen and carbapenem-resistant strains are great threat to hospitalized patients. This study is aimed to investigate the clinical characteristics, antimicrobial resistance patterns, and risk factors associated with carbapenem resistance in nosocomial, healthcare-associated (HCA), and community-acquired (CA) A. baumannii infections.

Methods

This study retrospectively reviewed cases in a tertiary hospital in southern China between January 1, 2019, and December 31, 2021. Univariate and multivariate logistic regression analyses were performed to identified the risk factors of carbapenem resistance in nosocomial, HCA and CA A. baumannii infections.

Results

A total of 391 patients with A. baumannii infection were included. Of these patients, 96 (24.6%) had nosocomial infections, 215 (55.0%) had HCA infections, and 80 (20.5%) had CA infections. The overall 30-day mortality rates of nosocomial and HCA infection patients was significantly higher than that of CA infection (P<0.05). The incidence of antimicrobial resistance was also higher in nosocomial and HCA bacteremia than that in CA bacteremia (P<0.05). Logistic regression analysis identified age ≥60 years, urethral catheterization, and exposure to two or more antibiotics as the independent risk factors for carbapenem-resistant A. baumannii (CRAB) infection in the nosocomial infection group and exposure to two or more antibiotics and endotracheal intubation in the HCA infection group. However, malignant tumors and hematological diseases were identified as protective factors against CRAB infection in the HCA group.

Conclusion

These data suggest that HCA A. baumannii infection is quite different from CA infection, with antimicrobial resistance and 30-day mortality rates similar to those of nosocomial infections. Additionally, the risk factors for CRAB development in the CA, HCA, and nosocomial groups were not the same, which may provides the help for controlling practices and instruction empirical clinical medication.

Acinetobacter spp. bloodstream infection in hematological patients: a 10-year single-center study

PURPOSE

This study investigated the clinical and antimicrobial characteristics of Acinetobacter spp. bloodstream infection (BSI) in hematological patients. Risk factors for 30-day mortality and carbapenem-resistant Acinetobacter spp. (CRA) BSI acquisition were also identified.

METHODS

We reviewed forty hematological patients with Acinetobacter spp. BSI in a large Chinese blood disease hospital between 2013 and 2022. The remaining CRA isolates were subjected to whole-genome sequencing.

RESULTS

The 30-day mortality rate was high at 35%. Hematological patients with Acinetobacter spp. BSI often presented with severe conditions and co-infections at multiple sites. All strains were colistin-susceptible and 40.0% were CR. Multivariate analysis identified several risk factors associated with CRA BSI acquisition, including previous exposure to carbapenems within 30 days and CRA colonization. Very severe aplastic anaemia, tetracycline-resistant Acinetobacter spp. BSI, and unresolved neutropenia after infection were closely associated with 30-day mortality. Non-survivors often presented with higher median PCT and CRP levels and severe complications, such as intracranial infection, cardiac dysfunction, respiratory failure, and severe sepsis or septic shock. Our study also identified inappropriate empirical antibiotic therapy as an independent predictor of 30-day mortality (OR: 11.234, 95% CI: 1.261-20.086, P = 0.030). This study was the first to report A. oleivorans as a human pathogen, and to identify its unique oxacillinase, OXA-325.

CONCLUSION

An environment-originated non-pathogenic species can become pathogenic when the body's immunity is compromised. Our results also highlighted the importance of improving neutropenia after infection, treating severe organ dysfunction, and administering appropriate empirical antibiotic therapy to reduce mortality in this patient population.

Antimicrobial peptide 2K4L disrupts the membrane of multidrug-resistant Acinetobacter baumannii and protects mice against sepsis

Antimicrobial peptides represent a promising therapeutic alternative for the treatment of antibiotic-resistant bacterial infections. 2K4L is a rationally-designed analog of a short peptide temporin-1CEc, a natural peptide isolated and purified from the skin secretions of the Chinese brown frog Rana chensinensis by substituting amino acid residues. 2K4L adopt an α-helical confirm in a membrane-mimetic environment and displayed an improved and broad-spectrum antibacterial activity against sensitive and multidrug-resistant Gram-negative and Gram-positive bacterial strains. Here, the action mechanism of 2K4L on multidrug resistant Acinetobacter baumannii (MRAB) and protection on MRAB-infected mice was investigated. The results demonstrated high bactericidal activity of 2K4L against both a multidrug resistant A. baumannii 0227 strain (MRAB 0227) and a sensitive A. baumannii strain (AB 22934), indicating a potential therapeutic advantage of this peptide. Strong positively-charged residues significantly promoted the electrostatic interaction on 2K4L with lipopolysaccharides (LPS) of the bacterial outer membrane. High hydrophobicity and an α-helical confirm endowed 2K4L remarkably increase the permeability of A. baumannii cytoplasmic membrane by depolarization of membrane potential and disruption of membrane integration, as well as leakage of fluorescein from the liposomes. Additionally, 2K4L at low concentrations inhibited biofilm formation and degraded mature 1-day-old MRAB 0227 biofilms by reducing the expression of biofilm-related genes. In an invasive A. baumannii infection model, 2K4L enhanced the survival of sepsis mice and decreased the production of the proinflammatory cytokines downregulating the phosphorylation level of signaling protein in MAPK and NF-κB signaling pathways, indicating that 2K4L represents a novel therapeutic antibiotic candidate against invasive multidrug-resistant bacterial strain infections.

Acinetobacter baumannii Bloodstream Infections: A Nationwide Study in Israel

Acinetobacter baumannii (Ab) bloodstream infections (BSIs) are a major public health concern and associated with high mortality. We describe the nationwide incidence, antimicrobial resistance, and mortality of Ab-BSI in Israel using laboratory-based BSI surveillance data from January 2018 to December 2019. During the study period, there were 971 Ab-BSI events (508 in 2018 and 463 in 2019), with an average annual incidence of 8.08/100,000 population. The median age of patients was 72 (IQR 62-83), and 56.4% were males. Two-thirds of Ab-BSI events were hospital-onset (HO), with median day of onset 16 (IQR 9-30). HO-BSI incidence was 0.62/10,000 patient-days (rate per 10,000 patient-days: 2.78, 1.17, and 0.2 for intensive care, medical, and surgical wards, respectively). Carbapenem susceptibility was 23.4%; 41.4% and 14.9% in community and HO events, respectively. The 14-day, 30-day, and 1-year mortality were 51.2%, 59.3%, and 81.4%, respectively. Carbapenem-resistant Ab-BSI were associated with a significantly higher 14-day, 30-day, and 1-year mortality (p < 0.001 for all). In the multivariable model, age (aHR 1.02) and carbapenem resistance (aHR 3.21) were independent predictors of 30-day mortality. In conclusion, Ab-BSIs pose a significant burden with high mortality, especially associated with antimicrobial resistance. Attention should be focused on prevention and improving treatment.

The significant role of Carbapenems-resistant Acinetobacter Baumannii in mortality rate of patients with COVID-19

Background: Infections caused by Acinetobacter baumannii, especially carbapenem-resistant (CR) strains, pose important challenges in patients with COVID-19 infection. Therefore, in the present study, we investigated co-infection and antimicrobial resistance patterns, as well as the role of A. baumannii in the outcome of patients with COVID-19.

Materials and methods: Between February 2019 and January 2021, 141 patients with A. baumannii infections were detected from seven different hospitals (A to G) in Arak, Iran, and the antibacterial susceptibility pattern of these isolates was evaluated using disk diffusion and E-test methods. Forty-seven of these patients were co-infected with COVID-19. During the study, the data about the clinical course, demographic data, and the role of A. baumannii infections in the mortality rate of COVID-19 patients were collected.

Results: Hospitals A and B reported the most patients, with 53 (38%) and 47 (33%), respectively. Additionally, most cases (105 cases, 75%) were reported from surgical and general ICUs. Mechanical ventilators were detected as predisposing factors in 95 (67%) patients, and infection was detected in 20% of patients on the 10th day after intubation. All of the A. baumannii isolates were resistant to different classes of antibiotics, such as carbapenems. Notably, 33% (47 patients) were also positive for COVID-19, and 68% (32 patients) died due to the infection. Statistical analysis showed a significant role of A. baumannii co-infection in the mortality rate of COVID-19 patients (p-value 0.05).

Conclusion: co-infection with A. baumannii is one of the most important challenges in COVID-19 patients. Our results showed that all isolated bacteria were CR and significantly increased mortality rates in COVID-19 patients.

The significant role of Carbapenems-resistant Acinetobacter Baumannii in mortality rate of patients with COVID-19

Background: Infections caused by Acinetobacter baumannii, especially carbapenem-resistant (CR) strains, pose important challenges in patients with COVID-19 infection. Therefore, in the present study, we investigated co-infection and antimicrobial resistance patterns, as well as the role of A. baumannii in the outcome of patients with COVID-19. Materials and methods: Between February 2019 and January 2021, 141 patients with A. baumannii infections were detected from seven different hospitals (A to G) in Arak, Iran, and the antibacterial susceptibility pattern of these isolates was evaluated using disk diffusion and E-test methods. Forty-seven of these patients were co-infected with COVID-19. During the study, the data about the clinical course, demographic data, and the role of A. baumannii infections in the mortality rate of COVID-19 patients were collected. Results: Hospitals A and B reported the most patients, with 53 (38%) and 47 (33%), respectively. Additionally, most cases (105 cases, 75%) were reported from surgical and general ICUs. Mechanical ventilators were detected as predisposing factors in 95 (67%) patients, and infection was detected in 20% of patients on the 10th day after intubation. All of the A. baumannii isolates were resistant to different classes of antibiotics, such as carbapenems. Notably, 33% (47 patients) were also positive for COVID-19, and 68% (32 patients) died due to the infection. Statistical analysis showed a significant role of A. baumannii co-infection in the mortality rate of COVID-19 patients (p-value 0.05). Conclusion: co-infection with A. baumannii is one of the most important challenges in COVID-19 patients. Our results showed that all isolated bacteria were CR and significantly increased mortality rates in COVID-19 patients.

A systematic review and meta-analysis for risk factor profiles in patients with resistant Acinetobacter baumannii infection relative to control patients

BACKGROUND

Acinetobacter baumannii is a major cause of nosocomial infections and high mortality rates. Evaluation of risk factors for such resistant infections may aid surveillance and diagnostic initiatives, as well as, can be crucial in early and appropriate antibiotic therapy.

OBJECTIVE

To identify the risk factors in patients with resistant A. baumannii infection with respect to controls.

METHODS

Prospective or retrospective cohort and case-control studies reporting the risk factors for resistant A. baumannii infection were collected through two data sources, MEDLINE/PubMed and OVID/Embase. Studies published in the English language were included while animal studies were excluded. The Newcastle-Ottawa Scale was used to assess the quality of studies. The odds ratio of developing antibiotic resistance in patients with A. baumannii infection was pooled using a random-effect model.

RESULTS

The results are based on 38 studies with 60878 participants (6394 cases and 54484 controls). A total of 28, 14, 25, and 11 risk factors were identified for multi-drug resistant (MDRAB), extensive-drug resistant (XDRAB), carbapenem-resistant (CRAB) and imipenem resistant A. baumannii infection (IRAB), respectively. In the MDRAB infection group, exposure to carbapenem (OR 5.51; 95% CI: 3.88-7.81) and tracheostomy (OR 5.01; 95% CI: 2.12-11.84) were identified with maximal pool odd's ratio. While previous use of amikacin (OR 4.94; 95% CI: 1.89-12.90) and exposure to carbapenem (OR 4.91; 95% CI: 2.65-9.10) were the foremost factors associated with developing CRAB infection. Further analysis revealed, mechanical ventilation (OR 7.21; 95% CI: 3.79-13.71) and ICU stay (OR 5.88; 95% CI: 3.27-10.57) as the most significant factors for XDRAB infection.

CONCLUSION

The exposure of carbapenem, amikacin (previous) and mechanical ventilation were the most significant risk factors for multidrug, extensive-drug, and carbapenem resistance in patients with A. baumannii infection respectively. These findings may guide to control and prevent resistant infections by identifying the patients at higher risk of developing resistance.

Multicenter Study of the Risk Factors and Outcomes of Bloodstream Infections Caused by Carbapenem-Non-Susceptible Acinetobacter baumannii in Indonesia

The prevalence of bacteremia caused by carbapenem-non-susceptible Acinetobacter baumannii (CNSAB) continues to increase, and it is associated with a high mortality rate. Early recognition of infection and mortality determinants risk factors is necessary for adequate antibiotic administration. We aimed to determine the risk factors and outcomes of CNSAB bacteremia in Indonesia. A multicenter case-control study was conducted in three referral hospitals in Indonesia. Data were collected retrospectively from January 2019 to December 2021. Cases were defined as patients with bacteremia where CNSAB was isolated from the blood, while the controls were patients with bacteremia caused by carbapenem-susceptible A. baumannii (CSAB). Risk factors for bacteremia and mortality associated with CNSAB bacteremia were determined using univariates analysis (chi-squared and Student's t-test or Mann-Whitney test) and multivariate logistic regression analysis. A total of 144 bacteremia patients were included, of whom 72 patients were for each case and control group. The final model of multivariate regression analysis revealed that bacteremia source from the lower respiratory tract (adjusted odds ratio (aOR): 3.24; 95% CI: 1.58-6.63, p = 0.001) and the use of central venous catheter (aOR: 2.56; 95% CI: 1.27-5.18; p = 0.009) were independent risk factors for CNSAB bacteremia. Charlson Comorbidity Index ≥ 4 (aOR: 28.56; 95% CI: 3.06-265.90, p = 0.003) and Pitt Bacteremia Score ≥ 4 (aOR: 6.44; 95% CI: 1.17-35.38; p = 0.032) were independent risk factors for mortality due to CNSAB bacteremia. Only high Pitt Bacteremia Score was an independent risk factor for mortality of CSAB bacteremia. In conclusion, we identified the risk factors for CNSAB-associated bacteremia and the risk factors for death, which are relevant for empiric therapy and infection control prevention, as well as prognosis evaluation of patients with bloodstream infections.

Adverse clinical outcomes associated with carbapenem-resistant Acinetobacter (CRA) infections: a systematic review and meta-analysis

Background

Carbapenem-resistant Acinetobacter (CRA) infections have been associated with increased morbidity and mortality in hospitalized patients. This systematic review and meta-analysis aimed to quantify the association between CRA infections and adverse clinical outcomes.

Methods

Three databases (i.e. PubMed, EMBASE and Scopus) were searched for epidemiological studies that compared mortality, severe sepsis or shock, or bacteraemia among adult inpatients with CRA infections and those with carbapenem-susceptible Acinetobacter (CSA) infections. The pooled ORs for the three outcomes were estimated using the inverse variance heterogeneity model.

Results

Thirty-four studies were included. Patients with CRA infections had higher odds of mortality (31 studies, OR = 2.10, 95% CI: 1.58–2.79, I²=60.6%) and severe sepsis or septic shock (7 studies, OR = 1.51, 95% CI: 1.09–2.09, I²=0%) compared with CSA-infected patients. There was no difference in the odds of bacteraemia (four studies, OR = 1.39, 95% CI: 0.79–2.46, I²=38.1%). CRA-infected patients presented with worse comorbidity at admission (e.g. APACHE score) (eight studies, standardized mean difference = 0.25, 95% CI: −0.01 to 0.52) and had lower frequency of appropriate antibiotic therapy. Results were consistent when pooling 16 study-adjusted risk estimates for mortality. There was no difference in risk of mortality from CRA infection when compared across geographical regions, country income, median year of enrolment and day of mortality from infection onset.

Conclusions

CRA-infected patients had worse clinical outcomes. This might be due to delay in appropriate antibiotic therapy, patients being sicker at admission and CRA strains potentially being more virulent than CSA strains. Improving appropriateness of antibiotic therapy in CRA-infected patients could reduce adverse clinical outcomes.

In vivo fitness of carbapenem-resistant Acinetobacter baumannii strains in murine infection is associated with treatment failure in human infections

OBJECTIVES

Mortality among patients with carbapenem-resistant Acinetobacter baumannii (CRAB) infections varies between studies. We examined whether in vivo fitness of CRAB strains is associated with clinical outcomes in patients with CRAB infections.

METHODS

Isolates were collected from patients enrolled in the AIDA trial with hospital-acquired pneumonia, bloodstream infections and/or urinary tract infections caused by CRAB. The primary outcome was 14-day clinical failure, defined as failure to meet all criteria: alive; haemodynamically stable; improved or stable Sequential Organ Failure Assessment (SOFA) score; improved or stable oxygenation; and microbiological cure of bacteraemia. The secondary outcome was 14-day mortality. We tested in vivo growth using a neutropenic murine thigh infection model. Fitness was defined based on the CFU count 24 hours after injection of an inoculum of 10⁵ CFU. We used mixed-effects logistic regression to test the association between fitness and the two outcomes.

RESULTS

The sample included 266 patients; 215 (80.8%) experienced clinical failure. CRAB fitness ranged from 5.23 to 10.08 log CFU/g. The odds of clinical failure increased by 62% for every 1-log CFU/g increase in fitness (OR 1.62, 95% CI 1.04-2.52). After adjusting for age, Charlson score, SOFA score and acquisition in the intensive care unit, fitness remained significant (adjusted OR 1.63, 95% CI 1.03-2.59). CRAB fitness had a similar effect on 14-day mortailty, although the association was not statistically significant (OR 1.56, 95% CI 0.95-2.57). It became significant after adjusting for age, Charlson score, SOFA score and recent surgery (adjusted OR 1.88, 95% CI 1.09-3.25).

CONCLUSIONS

In vivo CRAB fitness was associated with clinical failure in patients with CRAB infection.

The role of antimicrobial resistance on long-term mortality and quality of life in critically ill patients: a prospective longitudinal 2-year study

Background

In the recent era, antimicrobial resistance has been identified as one of the most important threats to human health worldwide. The rapid emergence of antibiotic-resistant pathogens (ABRP) in the modern intensive care unit (ICU) also represents a “nightmare scenario” with unknown clinical consequences. In the Greek ICU, in particular, gram negative ABRPs are now considered endemic. However, the possible longitudinal impact of ABRPs on long-term outcomes of ICU patients has not yet been determined.

Methods

In this two-year (January 2014-December 2015) single-centre observational longitudinal study, 351 non-neurocritical ICU patients ≥ 18 year-old were enrolled. Patients’ demographic, clinical and outcome data were prospectively collected. Quality-adjusted life years (QALY) were calculated at 6, 12, 18 and 24 months after ICU admission.

Results

Fifty-eight patients developed infections due to ABRP (ABRP group), 57 due to non-ABRP (non-ABRP group), and 236 demonstrated no infection (no-infection group) while in ICU. Multiple regression analysis revealed that multiple organ dysfunction syndrome score (OR: 0.676, 95%CI 0.584–0.782; P < 0.001) and continuous renal replacement therapy (OR: 4.453, 95%CI 1.805–10.982; P = 0.001) were the only independent determinants for ABRP infections in ICU. Intra-ICU, 90-day and 2-year mortality was 27.9%, 52.4% and 61.5%, respectively. Compared to the non-ABRP and no-infection group, the ABRP group demonstrated increased intra-ICU, 90-day and 2-year mortality (P ≤ 0.022), worse 2-year survival rates in ICU patients overall and ICU survivor subset (Log-rank test, P ≤ 0.046), and poorer progress over time in 2-year QALY kinetics in ICU population overall, ICU survivor and 2-year survivor subgroups (P ≤ 0.013). ABRP group was further divided into multi-drug and extensively-drug resistant subgroups [MDR (n = 34) / XDR (n = 24), respectively]. Compared to MDR subgroup, the XDR subgroup demonstrated increased ICU, 90-day and 2-year mortality (P ≤ 0.031), but similar 90-day and 2-year QALYs (P ≥ 0.549). ABRP infections overall (HR = 1.778, 95% CI 1.166–2.711; P = 0.008), as well as XDR [HR = 1.889, 95% CI 1.075–3.320; P = 0.027) but not MDR pathogens, were independently associated with 2-year mortality, after adjusting for several covariates of critical illness.

Conclusions

The present study may suggest a significant association between ABRP (especially XDR) infections in ICU and increased mortality and inability rates for a prolonged period post-discharge that requires further attention in larger-scale studies.

Nosocomial Non-fermentative gram negative bacteria bloodstream infections in children; Risk factors and clinical outcomes of carbapenem resistance

INTRODUCTION

Non-fermentative Gram-negative bacterias (NFGNBs) are a major cause of life threatening infections in hospitalized children. In this study, we aimed to evaluate the demographic and clinical characteristics of NFGNBs infections and identify the risk factors and outcomes of bloodstream infections (BSIs) caused by carbapenem-resistant (CR) NFGNBs infections.

METHODS

A retrospective cohort was designed to evaluate the patients with a BSI caused by NFGNBs between in January 2014 and December 2017.

RESULTS

A total of 131 episodes from 115 patients were evaluated. The mean age of the patients was 4.79±(4.74) year. The most commonly isolated NFGNBs species was Acinetobacter spp. (35.9%), Pseudomonas spp. (34.4%), and Stenotrophomonas maltophilia (13%). The rate of carbapenem-resistance was 38.2% in Acinetobacter spp. and 26.6% in Pseudomonas spp. The comparison of CR group with carbapenem-susceptible (CS) group showed statistical significance for the length of hospital stay prior to onset of infection and total hospital stay (P values were 0.001, 0.008). Based on the univariate analysis, requirement of mechanical ventilation, central venous catheter, nasogastric tube, Foley catheter, severe neutropenia (<100/mm3), prolonged neutropenia (≥14 days), prior intensive care unit admission and prior antimicrobial treatment (carbapenems, colistin, glycopeptide) were more common in carbapenem-resistant NFGNBs infections (P values are 0.001, 0.012, 0.000, 0.005, 0.042, 0.027, 0.007, 0.007). In patients with NFGNBs infections 14-day and 30-day mortality rates were %16.8 and 21.4%.

CONCLUSION

CR infections were more common in children with prolonged and severe neutropenia. Prior antimicrobial use and intensive care unit admission were more common in CR infections.

Prospective multi-center evaluation on risk factors, clinical characteristics and outcomes due to carbapenem resistance in Acinetobacter baumannii complex bacteraemia: experience from the Chinese Antimicrobial Resistance Surveillance of Nosocomial Infections (CARES) Network

Introduction. Increasing evidence demonstrates unfavourable outcomes in bloodstream infections (BSI) due to the carbapenem-resistant Acinetobacter baumannii complex (CRAB).Aim. To investigate the differences in risk factors, clinical characteristics and outcomes in patients with A. baumannii complex BSI stratified by carbapenem resistance, a prospective multi-center study was conducted.Methodology. Information was collected in a predefined form. A total of 317 cases was included for comparison between CRAB BSI vs. carbapenem-susceptible A. baumannii complex (CSAB) BSI. Among these cases, 229 cases were defined as CRAB BSI and 88 cases as CSAB BSI.Results. Univariable analysis showed that male gender, underlying neurologic disease, prior carbapenems exposure, intensive care unit (ICU) stay, presence of central venous catheter, endotracheal intubation, tracheotomy, Foley catheter, nasogastric intubation, lower respiratory tract infections and catheter-related infections were more prevalent in CRAB BSI. Only male gender, prior carbapenems exposure and presence of endotracheal intubation persisted as independent risk factors for acquiring CRAB BSI. Patients with CRAB BSI displayed unfavourable outcomes characterized by failure of pathogen clearance, continuous fever, disease aggravation and higher incidence of 30-day all-cause mortality. Multivariate analysis demonstrated carbapenem resistance as an independent risk factor for 30-day all-cause mortality.Conclusion. Our findings reveal the epidemiological differences between CRAB BSI and CSAB BSI in a Chinese cohort. Our data suggest that carbapenem resistance has a significant impact on mortality for patients with A. baumannii complex BSI, further strengthening the importance of active prevention and control strategies for the spread of CRAB in Chinese hospitals.

Predictive factors for sepsis by carbapenem resistant Gram-negative bacilli in adult critical patients in Rio de Janeiro: a case-case-control design in a prospective cohort study

Background

Studies have investigated risk factors for infections by specific species of carbapenem-resistant Gram-negative bacilli (CR-GNB), but few considered the group of GNB species and most of them were performed in the setting of bacteremia or hospital infection. This study was implemented to identify risk factors for sepsis by CR- and carbapenem-susceptible (CS) GNB in intensive care unit (ICU) patients to improve management strategies for CR-GNB sepsis.

Methods

We developed a case-case-control study from a prospective cohort of patients with systemic inflammatory response syndrome (SIRS), sepsis-2 or sepsis-3 criteria in which blood and other sample cultures were collected and antimicrobial therapy was instituted, in an adult clinical-surgical ICU, at tertiary public hospital in Rio de Janeiro, from August 2015 through March 2017.

Results

Among the total of 629 ICU admissions followed by 7797 patient-days, after applying inclusion and exclusion criteria we identified 184 patients who developed recurrent or single hospital-acquired sepsis. More than 90% of all evaluable cases of sepsis and 87% of control group fulfilled the modified sepsis-3 definition. Non-fermenting bacilli and ventilator-associated pneumonia predominated as etiology and source of CR-GNB sepsis. While Enterobacteriaceae and intra-abdominal surgical site plus urinary-tract infections prevailed in CS-GNB than CR-GNB sepsis. Carbapenemase production was estimated in 76% of CR-GNB isolates. Multivariate logistic regression analysis revealed previous infection (mostly hospital-acquired bacterial infection or sepsis) (OR = 4.28; 95% CI 1.77–10.35), mechanical ventilation (OR = 4.21; 95% CI 1.17–15.18), carbapenem use (OR = 3.42; 95% CI 1.37–8.52) and length of hospital stay (OR = 1.03; 95% CI 1.01–1.05) as independent risk factors for sepsis by CR-GNB. While ICU readmission (OR = 6.92; 95% CI 1.72–27.78) and nosocomial diarrhea (OR = 5.32; 95% CI 1.07–26.45) were factors associated with CS-GNB sepsis.

Conclusions

The investigation of recurrent and not only bacteremic episodes of sepsis was the differential of this study. The results are in agreement with the basic information in the literature. This may help improve management strategies and future studies on sepsis by CR-GNB.

Morbidity and mortality risk factors in emergency department patients with Acinetobacter baumannii bacteremia

BACKGROUND

Acinetobacter baumannii (AB) bacteremia is an increasingly common and often fatal nosocomial infection. Identification of morbidity and mortality risk factors for AB bacteremia in emergency department (ED) patients may provide ways to improve the clinical outcomes of these patients.

METHODS

The records for 51 patients with AB bacteremia and 51 patients without AB infection were collected and matched in a retrospective case-control study between 2013 and 2015 in a single-center ED. Risk factors were analyzed by Chi-square and multivariate logistic regression statistical models.

RESULTS

A significant risk factor for morbidity was the presence of a central venous catheter (CVC) (P<0.001). The mortality rate for the 51 patients with AB bacteremia was 68.6%. Risk factors for mortality were the presence of a CVC (P=0.021) and an ED stay longer than two weeks (P=0.015).

CONCLUSION

AB infections lead to high morbidity and mortality. The presence of a CVC was associated with higher morbidity and mortality in patients with AB bacteremia. Avoiding CVC insertions may improve outcomes in ED patients with AB bacteremia.

The clinical and epidemiological risk factors of infections due to multi-drug resistant bacteria in an adult intensive care unit of University Hospital Center in Marrakesh-Morocco

BACKGROUND

Intensive care units (ICUs) are considered epicenters of antibiotic resistance. The aim of this study is to determine clinical risk factors, epidemiology and the causative agents of multi-drug resistant bacteria in the ICU of the University Hospital in Marrakesh-Morocco.

METHODS

A one year case control study was carried out in our 10-bed clinical and surgical ICU from March 2015 to March 2016. The epidemiological surveillance was done by collecting data in the medical records with the help of a questionnaire. The antibiotic susceptibility testing was used following the recommendations of the Antibiogram Committee of the French Society of Microbiology and the European Committee for Antimicrobial Susceptibility Testing, 2015.

RESULTS

Among the 479 admitted patients, 305 bacteria were isolated and identified as Acinetobacter baumannii (31%), Enterobactereacae species (30%), and Staphylococcus (24%), P. aeruginosa (10%) and other bacterial strains (5%). The rate of MDR bacteria acquisition was 41% (124/305) with domination of A. baumannii resistant to imipenem (70%) and followed by Extended Spectrum β-lactamases producing Enterobacteriaceae, P. aeruginosa resistant to Ceftazidime, and Methicillin-resistant S. aureus (18%, 7%, and 5% respectively). The distribution of the common nosocomial infections were dominated by pneumonia, bacteremia, and catheter-related blood stream infections (39%, 29%, and 17%) respectively. Multivariate analysis identified lack of patient isolation precautions (OR: 7.500), use of quadri or triple therapy (OR: 5.596; OR: 5.175), and mechanical ventilation (OR: 4.926), as the most significant clinical and epidemiological factors associated with acquisition of MDR bacteria. The attributable mortality, in this ICU, of patients with MDR bacteria, is about 12%.

CONCLUSIONS

The incidence of MDR was higher compared with that of developed countries. The implementation of standard infection control protocols, active surveillance of MDR and generation of data on etiological agents and their antimicrobial susceptibility patterns are urgently needed in our hospital.

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.

Importance of control groups when delineating antibiotic use as a risk factor for carbapenem resistance, extreme-drug resistance, and pan-drug resistance in Acinetobacter baumannii and Pseudomonas aeruginosa: A systematic review and meta-analysis

BACKGROUND

Carbapenem-resistant (CR), extremely drug-resistant (XDR), and pan-drug-resistant (PDR) Acinetobacter baumannii and Pseudomonas aeruginosa pose a huge clinical threat. This study reviews the impact of control groups on the association of antecedent antibiotic use and the acquisition of CR/XDR/PDR A. baumannii and P. aeruginosa.

METHODS

Studies investigating the role of antibiotics as a risk factor for CR/XDR/PDR A. baumannii and P. aeruginosa acquisition in adult hospitalized patients from 1950 to 2016 were identified in the databases. These were divided into two groups: antibiotic-resistant versus antibiotic-sensitive pathogens (group I); antibiotic-resistant versus no infection (group II). A random-effects model was performed.

RESULTS

Eighty-five studies (46 A. baumannii, 38 P. aeruginosa, and one of both) involving 22 396 patients were included. CR was investigated in 60 studies, XDR in 20 studies, and PDR in two studies. Prior antibiotic exposure was associated with significant acquisition of CR/XDR/PDR A. baumannii and P. aeruginosa in both groups I and II (p<0.05). Antibiotic classes implicated in both groups included aminoglycosides, carbapenems, glycopeptides, and penicillins. Cephalosporin use was not associated with resistance in either group. Fluoroquinolone exposure was only associated with resistance in group I but not group II.

CONCLUSIONS

Control groups play an important role in determining the magnitudes of risk estimates for risk factor studies, hence careful selection is necessary. Antibiotic exposure increases the acquisition of highly resistant A. baumannii and P. aeruginosa, thus appropriate antibiotic use is imperative.

The prospective evaluation of risk factors and clinical influence of carbapenem resistance in children with gram-negative bacteria infection

BACKGROUND

Carbapenem-resistant gram-negative (CRGN) infections have been increasing in recent years and associated with significant morbidity, mortality, and health care costs. The aim of this study was to evaluate the epidemiologic and clinical risk characteristics, risk factors, and outcome of CRGN infections and to compare with carbapenem-sensitive gram-negative (CSGN) infections in children.

METHODS

Newly diagnosed CRGN infections in hospitalized children younger than age 18 years were prospectively recorded and all patients infected with a CSGN pathogen in the same unit within 48 hours of diagnosis were included in a control group between April 1, 2014, and December 31, 2014.

RESULTS

Twenty-seven patients with CRGN infections and 28 patients with CSGN infections were enrolled in this study. Ventilator-associated pneumonia was the most common type of infection in both groups. Prior exposure to carbapenems (relative risk [RR], 11.368; 95% confidence interval [CI], 1.311-98.589), prolonged hospitalization (RR, 5.100; 95% CI, 1.601-16.242) were found to be independent risk factors for acquiring CRGN infections. Septic shock was significantly more frequent in the CRGN group (RR, 9.450; 95% CI, 1.075-83.065). The in-hospital mortality was higher in the CRGN group (RR, 7.647; 95% CI, 1.488-39.290).

CONCLUSIONS

Prior carbapenem exposure and prolonged hospitalization are the most important risk factors for acquiring CRGN infections in our hospital. This study demonstrated, similar to previous reports, that carbapenem resistance increases morbidity, mortality, and health care costs.

Molecular epidemiology of carbapenem-resistant Acinetobacter baumannii in Greece: an extended review (2000–2015)

Carbapenem-resistant Acinetobacter baumannii (CRAB) is endemic in Greece. CRAB initially emerged in 2000 and since then, carbapenemases still have a crucial role in CRAB appearance, except for a few cases resulting from efflux pump or outer-membrane protein mechanisms. OXA-type carbapenemases present the highest prevalence worldwide and bla OXA-23-like and bla OXA-58-like are the most important genes found; VIM-yielding CRAB have also been detected, while a single CRAB isolate producing NDM has quite recently emerged in Greece. The predominant OXA-23 producers are associated with multilocus sequence typing Pasteur scheme sequence type 2 clonal strains of the international clone II. The emergence of colistin-resistant CRAB has complicated the treatment of such infections and the interpretation of susceptibility data. Infection control measures and adjusted antimicrobial treatment strategies could confine CRAB spread. The aim of this review is to go through the molecular epidemiology of CRAB, in an endemic area and highlight its potential future evolution.

Bloodstream infections in children caused by carbapenem-resistant versus carbapenem-susceptible gram-negative microorganisms: Risk factors and outcome

Carbapenems are often considered the last resort agents reserved for treatment of infections due to highly antimicrobial resistant organisms such as A. baumannii and P. aeruginosa. However, carbapenem-resistant Gram-negative (CRGN) pathogens have become much more prevalent in the last decade. The objective of this study was to determine risk factors for and outcome of bacteremia caused by Gram-negative microorganisms in a pediatric tertiary-care hospital. Among 97 patients with hospital-acquired Gram-negative bacteremia, 66 patients with carbapenem-susceptible Gram-negative pathogens (CSGN) were compared with the remaining 31 with CRGN isolates. The overall clinical response and microbiological response rates were 83.3% and 43.9% in CSGN group, and 54.8% and 32.3% in CRGN group, respectively (P=0.002 and P=0.004, respectively). The treatment failure and relapse rates were 18.2% and 6.1% in CSGN group, and 38.7% and 6.5% in CRGN group, respectively (P=0.03 in each). The infection-related mortality rates were 10.8% in the CSGN group and 32.3% in the CRGN group (P=0.01). The total length of stay in hospital before infection was longer in patients with CRGN bacteremia than that of the CSGN bacteremia (P=0.002). The extended spectrum antibiotic usage prior to infection was significantly different between the groups (P=0.008). Infections due to CRGN are generally associated with poorer patient outcomes. Longer hospital stay and extended spectrum antibiotic usage prior to infection are the most important risk factors for CRGN bacteremia in our cohort.

Association between infections caused by multidrug-resistant gram-negative bacteria and mortality in critically ill patients

The incidence of gram-negative multidrug-resistant (MDR) bacterial pathogens is increasing in hospitals and particularly in the intensive care unit (ICU) setting. The clinical consequences of infections caused by MDR pathogens remain controversial. The purpose of this review is to summarize the available data concerning the impact of these infections on mortality in ICU patients. Twenty-four studies, conducted exclusively in ICU patients, were identified through PubMed search over the years 2000-2015. Bloodstream infection was the only infection examined in eight studies, respiratory infections in four and variable infections in others. Comparative data on the appropriateness of empirical antibiotic treatment were provided by only seven studies. In ten studies the presence of antimicrobial resistance was not associated with increased mortality; on the contrary, in other studies a significant impact of antibiotic resistance on mortality was found, though, sometimes, mediated by inappropriate antimicrobial treatment. Therefore, a direct association between infections due to gram-negative MDR bacteria and mortality in ICU patients cannot be confirmed. Sample size, presence of multiple confounders and other methodological issues may influence the results. These data support the need for further studies to elucidate the real impact of infections caused by resistant bacteria in ICU patients.

Multidrug Resistance Acinetobacter Bacteremia Secondary to Ventilator-Associated Pneumonia: Risk Factors and Outcome

PURPOSE

Acinetobacter baumannii is a multidrug resistant (MDR), gram-negative bacterium commonly implicated in ventilator-associated pneumonia (VAP) in critically ill patients. Patients in the intensive care unit (ICU) with VAP often subsequently develop A baumannii bacteremia, which may significantly worsen outcomes.

MATERIALS AND METHODS

In this study, we retrospectively reviewed the clinical and laboratory records of 129 ICU patients spanning 6 years with MDR A baumannii VAP; 46 (35%) of these patients had concomitant MDR A baumannii bacteremia.

RESULTS

The ICU mortality rate was higher in patients with VAP having A baumannii bacteremia compared to nonbacteremic patients (32.4% vs 9.6% respectively, P < .005). Age >65 years, an Acute Physiology and Chronic Health Evaluation II (APACHE-II) score higher than 20, a Sequential Organ Failure Assessment (SOFA) score higher than 7 on the day of bacteremia, and the presence of comorbid disease (chronic obstructive pulmonary disease [COPD] and chronic renal failure) were found to be independent risk factors for in-hospital mortality in this population. Multidrug resistant A baumannii was not an independent risk factor for mortality.

CONCLUSION

Although the presence of comorbid diseases (COPD and chronic renal failure) and severity of disease (APACHE > 20 and SOFA >7) were found to be independent risk factors for ICU mortality, MDR A baumannii bacteremia was not an independent risk factor for mortality in our critically ill population.

Risk factors for extensive drug-resistance and mortality in geriatric inpatients with bacteremia caused by Acinetobacter baumannii

BACKGROUND

The aim of this study was to explore the risk factors for developing bacteremia caused by extensive drug-resistant (XDR) Acinetobacter baumannii and the associated mortality in geriatric inpatients.

METHODS

We conducted a retrospective study of 125 patients with A baumannii bacteremia between October 2008 and December 2013 at a medical center in China.

RESULTS

The 30-day hospital mortality rate was 55.2%. XDR A baumannii was detected in 31.2% of all cases. A logistic regression analysis suggested that chronic obstructive pulmonary disease, a bedridden status, and central venous catheters were associated with bacteremia caused by XDR A baumannii, with adjusted odds ratios (aORs) and 95% confidence intervals (CIs) of 2.59 (1.01-6.64), 4.08 (1.39-12.01), and 9.52 (1.90-47.56), respectively. Furthermore, intensive care unit (ICU) stay, bacteremia caused by XDR A baumannii, concurrent fungal infection, and age (70-80 years old and >80 years old) were associated with mortality, with aORs and 95% CIs of 3.16 (1.29-7.73), 4.01 (1.46-11.04), 3.20 (1.28-7.98), 4.31 (1.44-12.92), and 5.46 (1.94-15.35), respectively.

CONCLUSION

Bacteremia is associated with a high 30-day hospital mortality rate in geriatric inpatients. Furthermore, ICU stay, bacteremia caused by XDR A baumannii, concurrent fungal infection, and age are associated with increased mortality in geriatric inpatients with A baumannii bacteremia.

Risk factors for and impact of carbapenem-resistant Acinetobacter baumannii colonization and infection: matched case-control study

The objective of this investigation was to identify risk factors for carbapenem-resistant Acinetobacter baumannii (CRAB) and its association with mortality. A population-based matched case-control study using the computerized database of Clalit Health Services (CHS) in the period between 2007 and 2012 was conducted. Hospitalized patients with CRAB colonization or infection were compared to hospitalized patients without evidence of A. baumannii, matched by age, ward of hospitalization, season, Charlson score, and length of hospitalization. Risk factors for CRAB isolation were searched for using multivariate analysis. Association of CRAB and other risk factors with mortality were assessed in the cohort. A total of 1190 patients with CRAB were matched to 1190 patients without CRAB. Low socioeconomic status was independently associated with CRAB isolation and CRAB bacteremia [odds ratio 2.18, 95% confidence interval (CI) 1.02-5]. Other risk factors were invasive procedures and bacteremia with other pathogens prior to CRAB isolation, and various comorbidities. Among all patients, CRAB isolation was independently associated with increased mortality (hazard ratio 2.33, 95% CI 2.08-2.6). Socioeconomic status is associated with health outcomes. Our population-based study revealed an almost doubled risk for CRAB in patients at lower socioeconomic status and an association with healthcare exposure. CRAB was associated with mortality and might become a risk indicator for complex morbidity and mortality.

Mortality burden related to infection with carbapenem-resistant Gram-negative bacteria among haematological cancer patients: a retrospective cohort study

OBJECTIVES

Carbapenem-resistant Gram-negative bacteria (CRGNB) pose a clinical challenge. We attempted to estimate the mortality burden of CRGNB among haematological cancer patients.

METHODS

This was a retrospective cohort study. We included adult patients hospitalized in the haemato-oncological/bone marrow transplantation departments for chemotherapy, between 2008 and 2014, with Gram-negative aerobic bacteraemia. We compared patients with CRGNB and carbapenem-susceptible Gram-negative bacteraemia (CSGNB). The primary outcome was 14 day all-cause mortality. In addition, we assessed 1 year survival. Multivariable logistics regression analysis and adjusted Cox regression analysis were conducted. Analyses were adjusted to the propensity for CRGNB bacteraemia.

RESULTS

The cohort included mostly young patients (mean age 50.1 years) with acute leukaemia (264/423, 62.4%) and the median absolute neutrophil count at bacteraemia onset was 0 × 10(9)/L. The unadjusted 14 day mortality rate was higher for patients with CRGNB compared with CSGNB [45.6% (47/103) versus 15% (48/320), respectively (P < 0.001)]. Adjusting to baseline prognostic factors, infection characteristics and the propensity score retained a significant association between CRGNB and 14 day mortality (OR 5.14, 95% CI 2.32-11.38). Including only the first bacteraemic episode per patient, 1 year mortality was 74.7% (68/91) for patients with CRGNB versus 49.8% (119/239) for patients with CSGNB (P < 0.001). Adjusting for risk factors associated with 1 year mortality, the HR for mortality with CRGNB was 1.48 (95% CI 1-2.2). CRGNB bacteraemia was associated with several risk factors for mortality, including inappropriate empirical antibiotic treatment and less effective definitive antibiotics.

CONCLUSIONS

This study demonstrated a significant adjusted association between CRGNB and mortality up to 1 year among haemato-oncological patients receiving chemotherapy.

Which Multidrug-Resitant Bacteria are Emerging in Patients with Hematological Malignancies?: One-Year Report

The aim of this retrospective, observational study was to evaluate the outcomes of bacteremia attacks during neutropenic episodes caused by chemotherapy in patients with hematological cancers by assessing mortality, involved pathogens, antimicrobial therapy and treatment responses. Patients who were older than 14 years of age and developed at least one neutropenic episode after chemotherapy to treat hematological cancer between November 2011 and November 2012 were included in the study. We retrospectively collected demographic, treatment, and survival data for 68 patients with 129 neutropenic episodes. The mean age was 59.36 ± 15.22 years (range 17-80 years), and 41 cases were male. The mean Multinational Association of Supportive Care in Cancer score was 19.56 ± 9.04. A total of 37 (28 %) bacteremia attacks were recorded in 20 cases (29 %). Fatality rates were 50 % in the six cases with bacteremia caused by carbapenem-resistant Gram-negative bacteria; death occurred in two patients with carbapenem-resistant Acinetobacter baumannii and in one patient with carbapenem-resistant Pseudomonas aeruginosa. Clinical and microbiological responses were achieved using PIP-TAZ or CEP-SUL treatment in 80 % (16/20) of the cases with bacteremia caused by carbapenem-sensitive Gram-negative bacteria (CS-GNB). During 547 colonization-days in 21 (30 %) vancomycin-resistant enterococci (VRE)-colonized cases among 68 patients, vancomycin-resistant Enterococcus faecium bacteremia developed in two patients. Non-carbapenem-based therapy can cure most bacteremia attacks caused by CS-GNB in patients with hematological cancer. However, bacteremia and other infections caused by drug-resistant pathogens, such as A. baumannii, P. aeruginosa, and VRE, are a growing concern in hematological patients.

Mechanisms of β-lactam antimicrobial resistance and epidemiology of major community- and healthcare-associated multidrug-resistant bacteria

Alexander Fleming's discovery of penicillin heralded an age of antibiotic development and healthcare advances that are premised on the ability to prevent and treat bacterial infections both safely and effectively. The resultant evolution of antimicrobial resistant mechanisms and spread of bacteria bearing these genetic determinants of resistance are acknowledged to be one of the major public health challenges globally, and threatens to unravel the gains of the past decades. We describe the major mechanisms of resistance to β-lactam antibiotics - the most widely used and effective antibiotics currently - in both Gram-positive and Gram-negative bacteria, and also briefly detail the existing and emergent pharmacological strategies to overcome such resistance. The global epidemiology of the four major types of bacteria that are responsible for the bulk of antimicrobial-resistant infections in the healthcare setting - methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, Enterobactericeae, and Acinetobacter baumannii - are also briefly described.

Multidrug-resistant Acinetobacter baumannii infection among neonates in a neonatal intensive care unit at a medical center in central Taiwan

BACKGROUND

Few studies have focused on multidrug-resistant Acinetobacter baumannii (MDRAB) infection in neonates. The aim of this study was to investigate risk factors for mortality in neonates with MDRAB infection.

METHODS

This retrospective case-series study was conducted at the Children's Hospital of China Medical University, Taichung, Taiwan. All patients hospitalized between January 2010 and December 2013 in the neonatal intensive care unit (NICU) with MDRAB infections were reviewed.

RESULTS

A total of 67 isolates from 59 neonatal patients were positive for MDRAB. Of the 67 isolates, 38 were from blood (56.72%), 16 from sputum (23.88%), seven from pus (10.45%), three from ascites (4.48%), two from cerebrospinal fluid (2.99%), and one from pleural fluid (1.49%). There were five episodes of MDRAB clusters consisting of 28 cases during the study period. The mortality rate due to MDRAB sepsis was 20.34% (12/59). The statistically significant risk factors for mortality due to MDRAB infection were being infected with MDRAB within 7 days of admission to the NICU, use of umbilical vein catheters, absolute neutrophil count < 1500/mm(3), platelet count < 100,000/mm(3), and a delay in initiating adequate antibiotic treatment.

CONCLUSION

MDRAB infection is responsible for a high mortality rate among neonates in the NICU, especially in those who have neutropenia or thrombocytopenia. Infection control and appropriateness of the initial antimicrobial agent with colistin play an important role in reducing mortality.

Risk factors of mortality in patients with carbapenem-resistant Acinetobacter baumannii bacteremia

BACKGROUND/PURPOSE

Identification of risks of mortality for carbapenem-resistant Acinetobacter baumannii (CRAB), with early implementation of an appropriate therapy, is crucial for the patients' outcome. The aim of this study was to survey mortality risk factors in 182 patients with CRAB bacteremia in a medical center in Taiwan.

METHODS

A total of 182 isolates of CRAB bacteremia were collected from 2009 to 2012 in Mackay Memorial Hospital, Taipei, Taiwan These isolates were identified by using the genotypic method. Risk of attributable mortality analysis was carried out with a Cox proportional hazards model.

RESULTS

The 182 CRAB isolates belonged to 38 different pulsotypes. The attributable mortality rate of the 182 patients was 58.24%. The risk factors for attributable mortality included intensive care unit stay [hazard ratio (HR): 2.27; p = 0.011], an Acute Physiology and Chronic Health Evaluation II score of >20 (HR: 2.19; p < 0.001), respiratory tract as the origin of bacteremia (HR: 3.40; p < 0.001), and previous use of ceftriaxone (HR: 2.51; p = 0.011). The appropriateness of antimicrobial therapy was 18.87% (20/106) in the mortality group versus 88.16% (67/76) in the survivor group (p < 0.001). The sensitivity of CRAB to colistin was 100% and to tigecycline was 40.11%.

CONCLUSION

The risk factors for mortality for CRAB included intensive care unit stay, a high Acute Physiology and Chronic Health Evaluation II score, respiratory tract as the origin of bacteremia, and previous use of ceftriaxone. Early implementation of an antimicrobial agent that had the highest in vitro activity against CRAB in patients at risk of CRAB bacteremia and high mortality may improve their outcome.

Risk factors and outcome analysis of acinetobacter baumannii complex bacteremia in critical patients

OBJECTIVES

Acinetobacter baumannii complex bacteremia has been identified increasingly in critical patients admitted in ICUs. Notably, A. baumannii complex bacteremia has a high mortality rate, yet the risk factors associated with mortality remain unclear and controversial.

DESIGN

Retrospective study.

SETTING

All adult ICUs at a tertiary care medical center.

PATIENTS

All patients with A. baumannii complex bacteremia admitted in 2009-2010.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Risk factors for mortality were analyzed. Bacterial isolates were identified by 16S-23S ribosomal RNA intergenic spacer region sequencing for genospecies and genotyped by pulsed-field gel electrophoresis. Carbapenemase genes were detected by polymerase chain reaction and sequencing. A total of 298 patients met the inclusion criteria, including 73 (24.5%) infected by imipenem-resistant A. baumannii complex. The overall 30-day mortality was 33.6% (100 of 298). Imipenem-resistant A. baumannii complex bacteremia specifically showed a high mortality (69.9%) and was associated with prior use of broad-spectrum antibiotics for more than 5 days for treating ventilator-associated pneumonia before the occurrence of bacteremia. Mortality was associated with inappropriate initial antimicrobial therapy, which was correlated with imipenem-resistant A. baumannii complex but not with any specific genospecies. ISAba1-blaOXA-23-ISAba1 (Tn2006) was found in most (66.7%, 40 of 68) imipenem-resistant A. baumannii (genospecies 2) and also spread beyond species border to all imipenem-resistant genospecies 3 (2), 13TU (2), and 10 (1).

CONCLUSIONS

For critical patients with A. baumannii complex infection, ventilator-associated pneumonia in particular, the selective pressure from prior use of broad-spectrum antibiotics for 5 days or more increased risk of subsequent imipenem-resistant A. baumannii complex bacteremia. To reduce mortality, rapid identification of imipenem-resistant A. baumannii complex and early initiation of appropriate antimicrobial therapy in these high-risk patients are crucial.

Pathogenicity of clinical Acinetobacter baumannii isolates in a Galleria mellonella host model according to bla(OXA-40) gene and epidemiological outbreak status

Clinical studies have suggested that blaOXA-40-positive Acinetobacter baumannii isolates are associated with poor patient outcomes; however, reasons for unfavorable outcomes are difficult to discern in clinical studies. The objective of this study was to assess the virulence of carbapenem-resistant A. baumannii according to blaOXA-40 and epidemiological outbreak status in a Galleria mellonella model. Eight isolates of A. baumannii were studied. Nonoutbreak isolates and blaOXA-40-negative isolates more rapidly killed infected G. mellonella (P < 0.01).

Carbapenem resistance and mortality in patients with Acinetobacter baumannii infection: systematic review and meta-analysis

Acinetobacter baumannii has emerged as a major cause of healthcare-associated infections. Controversy exists as to whether antimicrobial resistance increases the risk of mortality. We conducted a systematic review and meta-analysis to examine this association. We searched MEDLINE and EMBASE databases up to May 2013 to identify studies comparing mortality in patients with carbapenem-resistant A. baumannii (CRAB) vs. carbapenem-susceptible A. baumannii (CSAB). A random-effects model was used to pool Odds Ratios (OR). Heterogeneity was examined using I(2). We included 16 observational studies. There were 850 reported deaths (33%) among the 2546 patients. Patients with CRAB had a significantly higher risk of mortality than patients with CSAB in the pooled analysis of crude effect estimates (crude OR = 2.22; 95% CI = 1.66, 2.98), although substantial heterogeneity was evident (heterogeneity I(2) = 55%). The association remained significant in the pooled adjusted OR of 10 studies. Studies reported that patients with CRAB compared to patients with CSAB were more likely to have severe underlying illness and also to receive inappropriate empirical antimicrobial treatment, which increases the risk of mortality. Our study suggests that carbapenem resistance may increase the risk of mortality in patients with A. baumannii infection. However, cautious interpretation is required because of the residual confounding factors and inadequate sample size in most studies.

Risk Factors for Mortality in Patients with Acinetobacter baumannii Bacteremia

Background

Acinetobacter baumannii, an opportunistic nosocomial pathogen that can cause significant morbidity and mortality, has emerged as a worldwide problem. The aim of this study was to evaluate the risk factors for mortality in patients with A. baumannii bacteremia.

Materials and Methods

We retrospectively evaluated 118 patients who had A. baumannii bacteremia between July 2003 and December 2011. The aim of this study was to identify the 30-day mortality in patients with A. baumannii bacteremia and relevant risk factors.

Results

The bacteremia-related 30-day mortality rate was 34.1%. Univariate analysis revealed that the risk factors for mortality included malignancy, longer hospital stay before bacteremia, intensive care unit (ICU) stay at the time of bacteremia, mechanical ventilation, use of a central venous catheter, unknown origin of bacteremia, bacteremia due to pneumonia, antimicrobial resistance to carbapenems, and elevated Acute Physiology and Chronic Health Evaluation II and Pitt bacteremia scores. Multivariate logistic regression analysis revealed that resistance to carbapenems (odds ratio [OR]: 4.01, 95% confidence interval [CI]: 1.51 to 0.68, P = 0.005), need for mechanical ventilation (OR: 3.97, 95% CI: 1.41 to 11.13, P = 0.005), and presence of malignancy (OR: 4.40, 95% CI: 1.60 to 12.08, P = 0.004) were significantly related to mortality risk.

Conclusions

Risk factors such as resistance to carbapenems, mechanical ventilation, and presence of malignancy were found to be associated with high mortality rates in the patients with A. baumannii bacteremia.

Clinical significance of multidrug-resistant Acinetobacter baumannii isolated from central venous catheter tip cultures in patients without concomitant bacteremia

BACKGROUND

The purpose of this study was to examine the clinical implications of a positive central venous catheter (CVC) tip culture with multidrug-resistant Acinetobacter baumannii (MRAB) in patients without concurrent bacteremia.

METHODS

This retrospective, multicenter study was conducted in 9 teaching hospitals in the Republic of Korea from May 2008 to April 2012. Study subjects included adult patients (aged ≥ 18 y) who yielded an MRAB-positive CVC tip culture without concurrent MRAB bacteremia. All patients were observed for the development of subsequent MRAB bacteremia for 6 months after CVC removal. Multivariable Firth logistic regression analysis was performed to determine predictors independently associated with subsequent MRAB bacteremia.

RESULTS

During the study period, subsequent MRAB bacteremia was observed in 18.8% of patients (21/112). Of the 112 patients, 23 (20.5%) did not show systemic inflammatory response syndrome (SIRS). None of the 23 patients without SIRS presented with subsequent MRAB bacteremia. Multivariable logistic regression analysis showed that prior administration of carbapenems (odds ratio (OR) 7.04, 95% confidence interval (CI) 1.43-34.77) or corticosteroids (OR 6.67, 95% CI 1.19-37.44), and C-reactive protein ≥ 40 mg/l (OR 18.11, 95% CI 2.22-148.07) were positive predictive factors. Prior acquisition of MRAB at a site other than the catheter (OR 0.10, 95% CI 0.03-0.39) was a negative predictive factor for developing MRAB bacteremia.

CONCLUSIONS

Our results suggest that patients with a CVC tip colonized with MRAB should be closely monitored for signs and symptoms of subsequent MRAB bacteremia.

Trends of mortality due to septicemia in Greece: an 8-year analysis

BACKGROUND

Infectious diseases are among the major causes of death worldwide. We evaluated the trends of mortality due to septicemia in Greece and compared it with mortality due to other infections.

METHODS

Data on mortality stratified by cause of death during 2003-2010 was obtained from the Hellenic Statistical Authority. Deaths caused by infectious diseases were grouped by site of infection and analyzed using SPSS 17.0 software.

RESULTS

45,451 deaths due to infections were recorded in Greece during the 8-year period of time, among which 12.2% were due to septicemia, 69.7% pneumonia, 1.5% pulmonary tuberculosis, 0.2% influenza, 0.5% other infections of the respiratory tract, 7.9% intra-abdominal infections (IAIs), 2.5% urinary tract infections (UTIs), 2.2% endocarditis or pericarditis or myocarditis, 1.6% hepatitis, 1% infections of the central nervous system, and 0.7% other infections. A percentage of 99.4% of deaths due to septicemia were caused by bacteria that were not reported on the death certificate (noted as indeterminate septicemia). More deaths due to indeterminate septicemia were observed during 2007-2010 compared to 2003-2006 (3,558 versus 1,966; p<0.05).

CONCLUSION

Despite the limitations related to the quality of death certificates, this study shows that the mortality rate due to septicemia has almost doubled after 2007 in Greece. Proportionally, septicemia accounted for a greater increase in the mortality rate within the infectious causes of death for the same period of time. The emergence of resistance could partially explain this alarming phenomenon. Therefore, stricter infection control measures should be urgently applied in all Greek healthcare facilities.

Impact of carbapenem resistance on clinical and economic outcomes among patients with Acinetobacter baumannii infection in Colombia

Acinetobacter baumannii is a major cause of healthcare-associated infection, often affecting critically ill patients. The purpose of the study was to examine the associations of carbapenem resistance with mortality, length of hospital stay and hospital costs among patients infected with A. baumannii in intensive-care units (ICUs) in Colombia. A prospective, multicentre cohort study was conducted among 165 patients with A. baumannii infection admitted to ICUs between April 2006 and April 2010. Patients with carbapenem-resistant A. baumannii had higher risk of 30-day mortality than patients with carbapenem-susceptible A. baumannii in the univariate analysis (unadjusted hazard ratio = 2.12; 95% CI 1.14-3.95; p 0.018). However, carbapenem resistance was not significantly associated with risk of mortality (adjusted hazard ratio = 1.45; 95% CI 0.74-2.87; p 0.28) after adjusting for APACHE II score and other confounding factors. We did not find a significant difference in length of stay in ICU after the onset of infection between the two groups in the multivariate analysis (adjusted mean = 13.1 days versus 10.5 days; p 0.14). The average total cost of hospitalization among patients with carbapenem-resistant A. baumannii was significantly higher than that among patients with carbapenem-susceptible A. baumannii in the multivariate analysis (adjusted cost; US$ 11 359 versus US$ 7049; p <0.001). Carbapenem resistance was not significantly associated with mortality, though we are unable to rule out an increased risk due to the limited sample size. Carbapenem resistance was associated with an additional cost of hospitalization.

Risk factors for carbapenem-resistant Gram-negative bacteremia in intensive care unit patients

PURPOSE

Carbapenem-resistant (CR) Gram-negative pathogens have increased substantially. This study was performed to identify the risk factors for development of CR Gram-negative bacteremia (GNB) in intensive care unit (ICU) patients.

METHODS

Prospective study; risk factors for development of CR-GNB were investigated using two groups of case patients: the first group consisted of patients who acquired carbapenem susceptible (CS) GNB and the second group included patients with CR-GNB. Both case groups were compared to a shared control group defined as patients without bacteremia, hospitalized in the ICU during the same period.

RESULTS

Eighty-five patients with CR- and 84 patients with CS-GNB were compared to 630 control patients, without bacteremia. Presence of VAP (OR 7.59, 95 % CI 4.54-12.69, p < 0.001) and additional intravascular devices (OR 3.69, 95 % CI 2.20-6.20, p < 0.001) were independently associated with CR-GNB. Presence of VAP (OR 2.93, 95 % CI 1.74-4.93, p < 0.001), presence of additional intravascular devices (OR 2.10, 95 % CI 1.23-3.60, p = 0.007) and SOFA score on ICU admission (OR 1.11, 95 % CI 1.03-1.20, p = 0.006) were independently associated with CS-GNB. The duration of exposure to carbapenems (OR 1.079, 95 % CI 1.022-1.139, p = 0.006) and colistin (OR 1.113, 95 % CI 1.046-1.184, p = 0.001) were independent risk factors for acquisition of CR-GNB. When the source of bacteremia was other than VAP, previous administration of carbapenems was the only factor related with the development of CR-GNB (OR 1.086, 95 % CI 1.003-1.177, p = 0.042).

CONCLUSIONS

Among ICU patients, VAP development and the presence of additional intravascular devices were the major risk factors for CR-GNB. In the absence of VAP, prior use of carbapenems was the only factor independently related to carbapenem resistance.

Anti-inflammatory and anti-superbacterial activity of polyphenols isolated from black raspberry

The fruit of the black raspberry (Rubus coreanus Miquel) has been employed in traditional medicine, and recent studies have demonstrated its measureable biological activities. However, the root of the black raspberry has not been studied. Therefore, in this study, we evaluated the anti-inflammatory and antibacterial properties of the root and unripe fruit polyphenols of the black raspberry. Both polyphenols proved to have anti-inflammatory activity as evidenced by the decreased nitric oxide (NO), cytokines (IL-1β , IL-6, and IL-10) and prostaglandin E2 (PGE₂) levels in lipopolysaccharide (LPS)-stimulated RAW 264.7 murine macrophages. However, root polyphenols showed stronger anti-inflammatory activity than fruit polyphenols. LPS-induced mRNA and protein expressions of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2 levels were also decreased, confirming the anti-inflammatory activity. Root polyphenols showed lethal activity against methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Acinetobacter baumannii (CRAB), and Bacillus anthracis. In contrast, the black raspberry fruit did not demonstrate these properties. These data provide the first demonstration that black raspberry root has potential anti-inflammatory and anti-superbacterial properties that can be exploited as alternatives for use in the food and cosmetic industries and/or as pharmaceuticals.

Risk factors and outcomes of carbapenem-resistant Acinetobacter baumannii bacteremia in neonatal intensive care unit: a case-case-control study

BACKGROUND

Carbapenem-resistant Acinetobacter baumannii (CRAB) has emerged as a serious threat among critically ill neonates.

METHODS

We performed a case-case-control study in a Thai neonatal intensive care unit to identify risk factors and outcomes for CRAB bacteremia. Case group (CG) I was defined as cases with CRAB (n = 14), and CG II was defined as cases with carbapenem-susceptible A. baumannii (n = 38) bacteremia. The control group (n = 44) was selected from all patients admitted before and after 3 days that CG I was identified, but had no infection.

RESULTS

The mean gestational age and birth weight of CG I, II and control were 33.5, 35.2 and 35.2 weeks and 1856.5, 2273.9 and 2309.5 g, respectively. By multivariate analysis, CG I was more likely to have had an umbilical artery catheter (adjusted odds ratio = 29.30; P = 0.019) whereas CG II was more likely exposed to ceftazidime (adjusted odds ratio = 5.19; P = 0.046) and aminoglycosides (adjusted odds ratio = 35.59; P = 0.002). There was a significant difference in history of cefoperazone/sulbactam (21.4% versus 0%; P = 0.01) and imipenem use (35.7% versus 0%; P < 0.001) among CG I compared with control. Crude mortality in CG I was higher than CG II (42.9% versus 13.2%; odds ratio = 5.0; P = 0.02).

CONCLUSION

Our cohort of neonatal CRAB bacteremia is characterized by a very high mortality. Infection-control interventions inclusive of strict adherence to infection-control process for central vascular line placement and maintenance as well as antimicrobial stewardship program are essential to help reduce CRAB bacteremia.

Epidemiology and antimicrobial resistance among commonly encountered bacteria associated with infections and colonization in intensive care units in a university-affiliated hospital in Shanghai

BACKGROUND/PURPOSE

The aim of this study was to classify intensive care unit (ICU) bacterial strains as either ICU-acquired or ICU-on-admission and to compare their epidemiological and antibiogram characteristics.

METHODS

The study was performed in a 1300-bed university-affiliated hospital from January 1, 2006 to December 31, 2010. Based on the time of ICU admission, ICU isolates were classified as ICU-acquired strains (appearing more than 48 hours after admission) or ICU-on-admission strains (appearing 48 hours or less from admission). The microbiological data before ICU admission, the microbiological data, and susceptibility testing were compared between the ICU-acquired and ICU-on-admission bacterial isolates.

RESULTS

The most common ICU-acquired strains were Acinetobacter baumannii (19.5%), Pseudomonas aeruginosa (15.6%), Stenotrophomonas maltophilia (11.5%), Staphylococcus aureus (10.7%), Enterococcus spp. (10.6%), and Klebsiella pneumoniae (9.7%). There were significant differences between ICU-acquired and ICU-on-admission isolates in the susceptibility rates of Gram-negative bacteria to antibiotics, especially the susceptibility of A. baumannii to imipenem [23.8% (ICU-acquired) vs. 44.4% (ICU-on-admission), p < 0.001] and meropenem (24.1% vs. 37.8%, p < 0.001), and the susceptibility of P. aeruginosa to imipenem (39.3% vs. 76.1%, p < 0.001) and meropenem (58.5% vs. 76.1%, p < 0.05). Furthermore, decreased susceptibility rates of A. baumannii and P. aeruginosa to carbapenems were correlated with an extended ICU stay (p < 0.05).

CONCLUSION

Because of decreasing susceptibility rates of pathogens (especially ICU-acquired strains) and a significant correlation with the length of ICU stay, intensivists should consider a patient's time of ICU admission and previous microbiological data and should distinguish ICU-acquired strains from non-ICU-acquired strains so as to initiate optimized empirical antibiotic therapy against ICU-acquired infections.

The influence of carbapenem resistance on mortality in solid organ transplant recipients with Acinetobacter baumannii infection

Background

Infection with carbapenem-resistant Acinetobacter baumannii has been associated with high morbidity and mortality in solid organ transplant recipients. The main objective of this study was to assess the influence of carbapenem resistance and other potential risk factors on the outcome of A. baumannii infection after kidney and liver transplantation.

Methods

Retrospective study of a case series of A. baumannii infection among liver and renal transplant recipients. The primary outcome was death associated with A. baumannii infection. Multivariate logistic regression was used to assess the influence of carbapenem resistance and other covariates on the outcome.

Results

Forty-nine cases of A. baumannii infection affecting 24 kidney and 25 liver transplant recipients were studied. Eighteen cases (37%) were caused by carbapenem-resistant isolates. There were 17 (35%) deaths associated with A. baumannii infection. In unadjusted analysis, liver transplantation (p = 0.003), acquisition in intensive care unit (p = 0.001), extra-urinary site of infection (p < 0.001), mechanical ventilation (p = 0.001), use of central venous catheter (p = 0.008) and presentation with septic shock (p = 0.02) were significantly related to a higher risk of mortality associated with A. baumannii infection. The number of deaths associated with A. baumannii infection was higher among patients infected with carbapenem-resistant isolates, but the difference was not significant (p = 0.28). In multivariate analysis, the risk of A. baumannii-associated mortality was higher in patients with infection acquired in the intensive care unit (odds ratio [OR] = 34.8, p = 0.01) and on mechanical ventilation (OR = 15.2, p = 0.04). Appropriate empiric antimicrobial therapy was associated with significantly lower mortality (OR = 0.04, p = 0.03), but carbapenem resistance had no impact on it (OR = 0.73, p = 0.70).

Conclusion

These findings suggest that A. baumannii-associated mortality among liver and kidney transplant recipients is influenced by baseline clinical severity and by the early start of appropriate therapy, but not by carbapenem resistance.