Attributable mortality of Acinetobacter baumannii infections in critically ill patients: a systematic review of matched cohort and case-control studies

Risk factors for multidrug-resistant and extensively drug-resistant Acinetobacter baumannii infection of patients admitted in intensive care unit: a systematic review and meta-analysis

BACKGROUND

Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Acinetobacter baumannii infections pose challenges for clinical treatment and cause high mortality, particularly in intensive care units (ICUs).

AIM

To systematically summarize and analyse the risk factors for MDR/XDR A. baumannii-infected patients admitted to ICUs.

METHODS

PubMed, Embase, Web of Science, and the Cochrane Library were searched for eligible original studies published in English before October 2023. Meta-analysis was conducted where appropriate, with mean differences (MDs) and odds ratios (ORs) calculated for continuous and nominal scaled data. The quality of included studies was assessed using the Newcastle-Ottawa Scale (NOS).

FINDINGS

Ten studies reporting 1199 ICU patients (604 from general ICUs, 435 from neonatal ICUs, and 160 from paediatric ICUs) from eight countries were included in our analysis. Risk factors associated with MDR A. baumannii infection among patients admitted to general ICUs included high Acute Physiology And Clinical Health II (APACHE Ⅱ) score (mean difference (MD): 7.52; 95% confidence interval (CI): 3.24-11.80; P = 0.0006), invasive procedures (odds ratio (OR): 3.47; 95% CI: 1.70-7.10; P = 0.0006), longer ICU stay (MD: 3.40; 95% CI: 2.94-3.86; P < 0.00001), and use of antibiotics (OR: 2.69; 95% CI: 1.22-5.94; P = 0.01). In the sub-group analysis, longer neonatal ICU stay (MD: 16.88; 95% CI: 9.79-23.97; P < 0.00001) was associated with XDR A. baumannii infection.

CONCLUSION

Close attention should be paid to patients with longer ICU stays, undergoing invasive procedures, using antibiotics, and with high APACHE Ⅱ scores to reduce the risk of MDR and XDR A. baumannii infections.

Efficacy of combination therapy with standard-dose carbapenem for treating nosocomial pneumonia caused by carbapenem-resistant Acinetobacter baumannii in intensive care units: A multicentre retrospective propensity score-matched study

Carbapenem-resistant Acinetobacter baumannii (CRAB) infection is common worldwide. Despite carbapenem resistance, standard-dose carbapenems are still used in clinical practice. Hence in this study, we aimed to compare the efficacy and outcomes of a regimen containing standard-dose carbapenems with those of a regimen lacking carbapenems during the treatment of critically ill patients with CRAB nosocomial pneumonia in the intensive care unit (ICU). Initially, 735 patients were recruited for this multicentre retrospective cohort study. After exclusion, time-window bias adjustment, and propensity score matching, multiple clinical outcomes were compared between the carbapenem-containing (CC) (n = 166) and no carbapenem-containing (NCC) (n = 166) groups. The CC group showed a higher risk of clinical failure on day 7 than the NCC group (44.6% vs. 33.1%, P = 0.043). The lengths of ICU stay (21 and 16 days, P = 0.024) and hospital stay (61 and 44 days, P = 0.003) were longer in the CC group than in the NCC group. Multivariate analysis showed that the CC regimen was associated with higher clinical failure (adjusted odds ratio (aOR) = 1.64, 95% CI = 1.05-2.56, P = 0.031) and lower microbiological eradication (aOR = 0.48, 95% CI = 0.23-1.00, P = 0.049) at day 7 than the NCC group. Thus, a regimen containing a standard dose of carbapenem should be prescribed with caution for treating CRAB nosocomial pneumonia in the ICU.

Maternal septic shock due to Acinetobacter lwoffii infection:a case report

The incidence of Acinetobacter infections has increased in recent years. Acinetobacter infections are resistant to most antibiotics and can be found in hospitalized patients. Pregnancies complicated by severe sepsis or septic shock are associated with a higher rate of preterm labor and delivery, fetal infection, and operative delivery. This case report describes septic shock due to Acinetobacter lwoffii infection in the 31st week of gestation. A 47-year-old woman, with a gestation of 31 weeks and one day, presented with a fever, and signs of bacterial infection on laboratory tests. Although the patient was started on tazobactam/piperacillin, she went into septic shock, and was transferred to our hospital. Cesarean section was performed at a gestation of 31 weeks and 4 days because of severe maternal pneumonia and non-reassuring fetal status. A. lwoffii was detected in blood cultures collected at the previous hospital, and susceptibility to piperacillin and meropenem to A. lwoffii was confirmed. The pneumonia responded to antibiotic treatment and there were no findings of infection in the neonate. Maternal sepsis is an infrequent but important complication, causing significant maternal and fetal morbidity and fetal and neonatal mortality; therefore, early antibiotic therapy is required to improve the clinical outcome.

Excess mortality and long-term disability from healthcare-associated carbapenem-resistant Acinetobacter baumannii infections: A nationwide population-based matched cohort study

BACKGROUND

Carbapenem resistance is perceived as a clinical challenge in the management of debilitated and immunocompromised patients who eventually will die from underlying diseases. We aimed to examine whether carbapenem resistance per se, rather than the underlying diseases, negatively affect outcomes, by comparing the excess mortality and morbidity from healthcare-associated infections (HAIs) caused by carbapenem-resistant Acinetobacter baumannii (CRAB) and carbapenem-susceptible A. baumannii (CSAB).

METHODS

This was a nationwide retrospective matched cohort study of hospitalized patients in 96 hospitals which participated in Taiwan Nosocomial Infection Surveillance (TNIS). A total of 2,213 patients with A. baumannii HAIs were individually matched to 4,426 patients without HAIs. Main outcomes were excess risks for one-year all-cause mortality and one-year new-onset chronic ventilator dependence or dialysis-dependent end-stage renal disease.

RESULTS

Excess one-year mortality was 27.2% in CRAB patients, compared with their matched uninfected inpatients, as well as 15.4% in CSAB patients (also compared with their matched uninfected inpatients), resulting in an attributable mortality of 11.8% (P <0.001) associated with carbapenem resistance. The excess risk associated with carbapenem resistance for new-onset chronic ventilator dependence was 5.2% (P <0.001). Carbapenem resistance was also associated with an extra cost of $2,511 per case of A. baumannii HAIs (P <0.001).

CONCLUSION

Carbapenem resistance is associated with a significant disease burden in terms of excess mortality, long-term ventilator dependence, and medical cost. Further studies on effects of antimicrobial stewardship programs in decreasing this burden are warranted.

Global Risk Maps of Climate Change Impacts on the Distribution of Acinetobacter baumannii Using GIS

Impacts of climate change rank among the century's most significant ecological and medical concerns. As a result of climatic changes, the distribution of some bacterial species will alter across time and space. Numerous bacterial infections will reorganize as a result worldwide. Acinetobacter baumannii Bouvet and Grimont is one of the most significant and frequently occurring bacteria identified in soil and air. The COVID-19 pandemic has changed how bacteriologists perceive this species as a new threat to human health. In order to estimate the existing and future worldwide distribution of A. baumannii under various climate change scenarios, about 1000 A. baumannii occurrence records were employed. Given its superior accuracy and dependability versus alternative modeling techniques, maximum entropy implemented in MaxEnt was selected as the modeling tool. The bioclimatic variable that contributes the most to the distribution of A. baumannii is the mean temperature of the coldest quarter (bio_11). The created current distribution model agreed with the species' actual globally dispersed distribution. It is projected that A. baumannii will experience a severe range expansion due to the increase in temperature brought on by global warming in different regions of its range. According to the risk maps created for 2050 and 2070 using two alternative RCPs, there are various regions that will be under risk of this bacterium as a result of rising temperature. Future data science and GIS evaluation of the current results are necessary, especially on a local level.

Effect of Phenylalanine-Arginine Beta-Naphthylamide on the Values of Minimum Inhibitory Concentration of Quinolones and Aminoglycosides in Clinical Isolates of Acinetobacter baumannii

(1) Background: Acinetobacter baumannii has become the most important pathogen responsible for nosocomial infections in health systems. It expresses several resistance mechanisms, including the production of β-lactamases, changes in the cell membrane, and the expression of efflux pumps. (2) Methods: A. baumannii was detected by PCR amplification of the blaOXA-51-like gene. Antimicrobial susceptibility to fluoroquinolones and aminoglycosides was assessed using the broth microdilution technique according to 2018 CLSI guidelines. Efflux pump system activity was assessed by the addition of a phenylalanine-arginine beta-naphthylamide (PAβN) inhibitor. (3) Results: A total of nineteen A. baumannii clinical isolates were included in the study. In an overall analysis, in the presence of PAβN, amikacin susceptibility rates changed from 84.2% to 100%; regarding tobramycin, they changed from 68.4% to 84.2%; for nalidixic acid, they changed from 73.7% to 79.0%; as per ciprofloxacin, they changed from 68.4% to 73.7%; and, for levofloxacin, they stayed as 79.0% in both groups. (4) Conclusions: The addition of PAβN demonstrated a decrease in the rates of resistance to antimicrobials from the family of quinolones and aminoglycosides. Efflux pumps play an important role in the emergence of multidrug-resistant A. baumannii strains, and their inhibition may be useful as adjunctive therapy against this pathogen.

IgYs: on her majesty's secret service

There has been an increasing interest in using Immunoglobulin Y (IgY) antibodies as an alternative to "classical" antimicrobials. Unlike traditional antibiotics, they can be utilized on a continual basis without leading to the development of resistance. The veterinary IgY antibody market is growing because of the demand for minimal antibiotic use in animal production. IgY antibodies are not as strong as antibiotics for treating infections, but they work well as preventative agents and are natural, nontoxic, and easy to produce. They can be administered orally and are well tolerated, even by young animals. Unlike antibiotics, oral IgY supplements support the microbiome that plays a vital role in maintaining overall health, including immune system function. IgY formulations can be delivered as egg yolk powder and do not require extensive purification. Lipids in IgY supplements improve antibody stability in the digestive tract. Given this, using IgY antibodies as an alternative to antimicrobials has garnered interest. In this review, we will examine their antibacterial potential.

Healthcare-Associated Bloodstream Infections Due to Multidrug-Resistant Acinetobacter baumannii in COVID-19 Intensive Care Unit: A Single-Center Retrospective Study

Healthcare-associated infections are an emerging cause of morbidity and mortality in COVID-19 intensive care units (ICUs) worldwide, especially those caused by multidrug-resistant (MDR) pathogens. The objectives of this study were to assess the incidence of bloodstream infections (BSIs) among critically ill COVID-19 patients and to analyze the characteristics of healthcare-associated BSIs due to MDR Acinetobacter baumannii in an COVID-19 ICU. A single-center retrospective study was conducted at a tertiary hospital during a 5-month period. The detection of carbapenemase genes was performed by PCR and genetic relatedness by pulsed-field gel electrophoresis (PFGE) and multilocus-sequence typing. A total of 193 episodes were registered in 176 COVID-19 ICU patients, with an incidence of 25/1000 patient-days at risk. A. baumannii was the most common etiological agent (40.3%), with a resistance to carbapenems of 100%. The blaOXA-23 gene was detected in ST2 isolates while the blaOXA-24 was ST636-specific. PFGE revealed a homogeneous genetic background of the isolates. The clonal spread of OXA-23-positive A. baumannii is responsible for the high prevalence of MDR A. baumannii BSIs in our COVID-19 ICU. Further surveillance of resistance trends and mechanisms is needed along with changes in behavior to improve the implementation of infection control and the rational use of antibiotics.

Clinical Characteristics and Prognosis Analysis of Acinetobacter baumannii Bloodstream Infection Based on Propensity Matching

PURPOSE

In view of the fact that Acinetobacter baumannii bloodstream infection(BSI) is a great threat to human survival, early identification of the risk factors affecting prognosis will be of great benefit to the clinic.

PATIENTS AND METHODS

A propensity score matching method was used to collect patients identified with Acinetobacter baumannii BSI from 2016 to 2020 from a reputable hospital in China.

RESULTS

A total of 398 patients were considered. According to the 28-day prognosis, they were divided into the survival group 150 (37.7%) and the death group 248 (62.3%), and the prognosis was analyzed. Subsequently, Propensity score matching was adjusted for variables with p-values

CONCLUSION

The existence of drug resistance with Acinetobacter baumannii only leads to Inappropriate empirical antibiotic therapy, ultimately, Inappropriate empirical antibiotic therapy was the direct predictor of mortality.

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Key Words

• Acinetobacter baumannii
• bloodstream infection
• inappropriate empirical antibiotic therapy
• prognosis
• propensity score matching

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MESH Headings Collapse

Grants

• Young And Middle-aged Scientific And Technological Innovation Jie-qing Talent Project
• Henan Province’s Medical Science And Technology Research Provincial And Ministerial Joint Construction Of Key Projects
• Henan Province Science and Technology Research Project

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Affiliation(s)

Jinghui Wang Department of Intensive Care Unit, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, People’s Republic of China
Jun Zhang Department of Pharmacy, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, People’s Republic of China
Zhuang-hao Wu Department of Intensive Care Unit, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, People’s Republic of China
Lei Liu Department of Cardiovascular Surgery, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, People’s Republic of China
Zijun Ma Department of Intensive Care Unit, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, People’s Republic of China
Cheng-cheng Lai Department of Intensive Care Unit, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, People’s Republic of China
Yong-gang Luo Department of Intensive Care Unit, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, People’s Republic of China

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Co-isolates of Acinetobacter baumannii complex in polymicrobial infections: a meta-analysis

Background.Acinetobacter baumannii complex (ABC) infections are commonly polymicrobial. Examining which pathogens are most commonly co-isolated with ABC is an important first step for assessing disease potential due to pathogen-pathogen interactions.

Methods. Based on a systematic search of PubMed, Scopus and CENTRAL, we estimated percent proportions of co-isolates in polymicrobial pulmonary and bloodstream ABC infections using random-effects meta-analysis.

Efficacy of Eravacycline Versus Best Previously Available Therapy for Adults With Pneumonia Due to Difficult-to-Treat Resistant (DTR) Acinetobacter baumannii

BACKGROUND

Multidrug-resistant Acinetobacter baumannii remains challenging to treat. Although eravacycline has in vitro activity against this pathogen, there are no studies evaluating outcomes.

OBJECTIVE

To assess the efficacy of eravacycline compared with best previously available therapy in adults with difficult-to-treat resistant (DTR) A. baumannii pneumonia.

METHODS

This was a retrospective study of adults hospitalized for pneumonia with DTR A. baumannii. Patients receiving eravacycline were compared with those receiving best previously available therapy. The primary outcome was 30-day in-hospital mortality. Secondary outcomes included clinical cure at Day 14, hospital and intensive care unit (ICU) length of stay, microbiologic cure, and readmission within 90 days with a positive A. baumannii respiratory culture.

RESULTS

Ninety-three patients were included, with 27 receiving eravacycline. Eravacycline was associated with higher 30-day mortality (33% vs 15%; P = 0.048), lower microbiologic cure (17% vs 59%; P = 0.004), and longer durations of mechanical ventilation (10.5 vs 6.5 days; P = 0.016). At baseline, eravacycline patients had more A. baumannii bacteremia and coinfection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Among bacteremic patients, all 4 receiving eravacycline died by Day 30 and both patients receiving best previously available therapy survived. Upon exclusion of patients with bacteremia and SARS-CoV-2, there were no differences between the groups across any outcomes.

CONCLUSIONS

Eravacycline-based combination therapy had similar outcomes to best previously available combination therapy for adults with DTR A. baumannii pneumonia. However, eravacycline should be used with caution in the setting of bacteremia as outcomes were poor in this population.

C6 Hydroxymethyl-Substituted Carbapenem MA-1-206 Inhibits the Major Acinetobacter baumannii Carbapenemase OXA-23 by Impeding Deacylation

Acinetobacter baumannii has become a major nosocomial pathogen, as it is often multidrug-resistant, which results in infections characterized by high mortality rates. The bacterium achieves high levels of resistance to β-lactam antibiotics by producing β-lactamases, enzymes which destroy these valuable agents. Historically, the carbapenem family of β-lactam antibiotics have been the drugs of choice for treating A. baumannii infections. However, their effectiveness has been significantly diminished due to the pathogen’s production of carbapenem-hydrolyzing class D β-lactamases (CHDLs); thus, new antibiotics and inhibitors of these enzymes are urgently needed. Here, we describe a new carbapenem antibiotic, MA-1-206, in which the canonical C6 hydroxyethyl group has been replaced with hydroxymethyl. The antimicrobial susceptibility studies presented here demonstrated that this compound is more potent than meropenem and imipenem against A. baumannii producing OXA-23, the most prevalent CHDL of this pathogen, and also against strains producing the CHDL OXA-24/40 and the class B metallo-β-lactamase VIM-2. Our kinetic and mass spectrometry studies revealed that this drug is a reversible inhibitor of OXA-23, where inhibition takes place through a branched pathway. X-ray crystallographic studies, molecular docking, and molecular dynamics simulations of the OXA-23-MA-1-206 complex show that the C6 hydroxymethyl group forms a hydrogen bond with the carboxylated catalytic lysine of OXA-23, effectively preventing deacylation. These results provide a promising strategy for designing a new generation of CHDL-resistant carbapenems to restore their efficacy against deadly A. baumannii infections.

Microbiology and Outcome of Peritoneal Dialysis-Related Peritonitis in Elderly Patients: A Retrospective Study in China

Objective

The number of elderly patients on peritoneal dialysis (PD) has rapidly increased in the past few decades. We sought to explore the microbiology and outcomes of peritonitis in elderly PD patients compared with younger PD patients.

Methods

We conducted a retrospective study to analyze the clinical characteristics, causative organism distribution, and outcome of all PD patients who developed peritonitis between September 1, 2014 and December 31, 2020, from Second Xiangya Hospital, Central South University, China. Patients who experienced peritonitis were separated into elderly and younger groups. The elderly was defined as ≥ 65 years old at the initiation of PD.

Results

Among 1,200 patients, 64(33.9%) in elderly (n = 189) and 215 (21.3%) in younger (n = 1,011) developed at least one episode of peritonitis. A total of 394 episodes of peritonitis occurred in 279 patients. Of these, 88 episodes occurred in 64 elderly patients, and 306 episodes occurred in 215 younger patients. Gram-positive bacteria were the main causative organisms in elderly and younger patients (43.2% and 38.0%, respectively). Staphylococcus and Escherichia coli were the most common gram-positive and gram-negative bacteria, respectively. Fungal peritonitis in elderly patients was higher compared with younger patients (χ2 = 6.55, P = 0.01). Moreover, Acinetobacter baumannii (χ ²=9.25, P = 0.002) and polymicrobial peritonitis (χ ² = 6.41, P = 0.01) in elderly patients were also significantly higher than that in younger patients. Additionally, elderly PD patients had higher peritonitis-related mortality than younger patients (χ ² = 12.521, P = 0.000), though there was no significant difference in catheter removal between the two groups. Kaplan-Meier analysis showed that cumulative survival was significantly lower in elderly patients than younger patients (log rank = 7.867, p = 0.005), but similar technical survival in both groups (log rank = 0.036, p = 0.849).

Conclusions

This retrospective study demonstrated that elderly PD patients were more likely to develop Acinetobacter baumannii, fungal and polymicrobial peritonitis than younger PD patients. In addition, peritonitis-related mortality was significantly higher in elderly patients, whereas peritonitis-related catheter removal was comparable between elderly and younger PD patients. Understanding microbiology and outcome in elderly patients will help to reduce the incidence of PD-associated peritonitis and improve the quality of life.

High Frequency of Class I and II Integrons and the Presence of aadA2 and dfrA12 Gene Cassettes in the Clinical Isolates of Acinetobacter baumannii from Shiraz, Southwest of Iran

Background: Acinetobacter baumannii is a global concern that causes healthcare-associated infections due to multidrug resistance against commercially available antimicrobial agents. Objectives: The present study was conducted to determine the antimicrobial susceptibility of A. baumannii isolates from clinical specimens in Shiraz, Iran. In addition, the possible relationship of susceptibility patterns with the presence of integrons and related gene cassettes is investigated. Methods: A. baumannii isolates were collected, and their susceptibility to various antibiotics was tested using the Kirby-Bauer disk diffusion method. Moreover, molecular analyses were performed to detect the presence of the OXA-51-like gene, as well as class I, II, and III integrons, and associated gene cassettes. Results: The majority of isolates were resistant to imipenem (99.4%), piperacillin (98.2%), gentamycin (98.2%), meropenem (97.7%), ceftazidime (95.4%), amikacin (95.4%), and trimethoprim-sulfamethoxazole (90.8%). All strains showed multidrug resistance to the tested antibiotics. The distribution analysis of integrons genes revealed that 90.2, 72.4, and 12.1% of the isolates carried intI1, intI2, and intI3 genes, respectively. Moreover, two types of prevalent gene cassettes, including aad and dfr, were detected in class 1 integron-carrying strains. Conclusions: The current study showed the high prevalence of A. baumannii isolates harboring integrons in our investigated medical center, which may indicate the distribution of multidrug resistance events. The different gene cassette arrays in the present study highlight the remarkable role of geographical issues in disseminating multidrug-resistant isolates. This could be attributed to distinct therapeutic interventions in different areas. The results demonstrate the necessity of continuous surveillance to prevent the distribution of multidrug resistance among A. baumannii strains in Iran.

The Distribution of Multidrug-resistant Microorganisms and Treatment Status of Hospital-acquired Pneumonia/Ventilator-associated Pneumonia in Adult Intensive Care Units: a Prospective Cohort Observational Study

BACKGROUND

It is essential to determine the distribution of the causative microorganisms in the region and the status of local antibiotic resistance for the proper treatment of hospital-acquired pneumonia/ventilator-associated pneumonia (HAP/VAP). This study aimed to investigate the occurrence and causative strains of HAP/VAP, distribution of resistant bacteria, use of antibiotics, and the ensuing outcomes of patients in Korea.

METHODS

A multicenter prospective observational cohort study was conducted among patients with HAP/VAP admitted to the medical intensive care unit of 5 tertiary referral centers between August 2012 and June 2015. Patients' demographic and clinical data were collected.

RESULTS

A total of 381 patients were diagnosed with HAP/VAP. Their median age was 69 (59-76) years and 71% were males. A majority of the patients (88%) had late-onset (> 5 days) HAP/VAP. One-quarter of the patients (n = 99) had at least one risk factor for multidrug-resistant (MDR) pathogens, such as prior intravenous antibiotic use within the last 90 days. Microbiological specimens were mostly obtained noninvasively (87%) using sputum or endotracheal aspirates. Pathogens were identified in 235 (62%) of the 381 patients. The most common bacterial pathogen was Acinetobacter baumannii (n = 89), followed by Staphylococcus aureus (n = 52), Klebsiella pneumoniae (n = 25) and Pseudomonas aeruginosa (n = 22). Most of isolated A. baumannii (97%) and S. aureus (88%) were multidrug resistant. The most commonly used empirical antibiotic regimens were carbapenem-based antibiotics (38%), followed by extended-spectrum penicillin/β-lactamase inhibitor (34%). Glycopeptide or linezolid were also used in combination in 54% of patients. The 28-day mortality rate of the patients with HAP/VAP was 30% and the 60-day mortality was 46%. Patients who used empirical antibiotics appropriately had significantly lower mortality rates than those who did not (28-day mortality: 25% vs. 40%, P = 0.032; 60-day mortality: 41% vs. 55%, P = 0.032, respectively). Administration of appropriate empirical antibiotics (odds ratio [OR], 0.282; confidence interval [CI], 0.092-0.859; P = 0.026), Day 7 treatment failure (OR, 4.515; CI, 1.545-13.192; P = 0.006), and APACHE II score on day 1 (OR, 1.326; CI, 0.988-1.779; P = 0.012) were the factors that determined the 28-day mortality in patients with HAP who had identified bacteria as pathogens.

CONCLUSION

In HAP/VAP patients, there was a large burden of MDR pathogens, and their associated mortality rate was high. Proper selection of empirical antibiotics was significantly associated with the patient's prognosis; however, there was a discrepancy between major pathogens and empirical antibiotic therapy.

Whole-Genome Sequencing Elucidates the Epidemiology of Multidrug-Resistant Acinetobacter baumannii in an Intensive Care Unit

The nosocomial pathogen Acinetobacter baumannii is a frequent cause of healthcare-acquired infections, particularly in critically ill patients, and is of serious concern due to its potential for acquired multidrug resistance. Whole-genome sequencing (WGS) is increasingly used to obtain a high-resolution view of relationships between isolates, which helps in controlling healthcare-acquired infections. Here, we conducted a retrospective study to identify epidemic situations and assess the percentage of transmission in intensive care units (ICUs). Multidrug-resistant A. baumannii (MDR-AB) were continuously isolated from the lower respiratory tract of different patients (at the first isolation in our ICU). We performed WGS, pulsed-field gel electrophoresis (PFGE), and multilocus-sequence typing (MLST) analyses to elucidate bacterial relatedness and to compare the performance of conventional methods with WGS for typing MDR-AB. From June 2017 to August 2018, A. baumannii complex strains were detected in 124 of 796 patients during their ICU stays, 103 of which were MDR-AB. Then we subjected 70 available MDR-AB strains to typing with WGS, PFGE, and MLST. Among the 70 A. baumannii isolates, 38 (54.29%) were isolated at admission, and 32(45.71%) were acquisition isolates. MLST identified 12 unique sequence types, a novel ST (ST2367) was founded. PFGE revealed 16 different pulsotypes. Finally, 38 genotypes and 23 transmissions were identified by WGS. Transmission was the main mode of MDR-AB acquisition in our ICU. Our results demonstrated that WGS was a discriminatory technique for epidemiological healthcare-infection studies. The technique should greatly benefit the identification of epidemic situations and controlling transmission events in the near future.

Ten-Year Changes in Bloodstream Infection With Acinetobacter Baumannii Complex in Intensive Care Units in Eastern China: A Retrospective Cohort Study

Background: There is little evidence on the changing prevalence, microbiological profile, and outcome of nosocomial Acinetobacter baumannii complex (ABC)-caused bloodstream infection (ABCBSI) specified in intensive care units (ICUs) in long-term studies, especially in China. Objective: We aimed to investigate changes in incidence, antibiotic resistance, therapy, and prognosis of ABCBSI in ICUs in eastern China during 2009-2018. Methods: A multicenter retrospective cohort study was conducted, and microbiological and clinical data for patients with ABCBSI acquired in nine adult ICUs in eastern China from 2009 to 2018. Results: A total of 202 cases were enrolled. For the years 2009-2010, 2011-2012, 2013-2014, 2015-2016, and 2017-2018, the incidence of ABCBSI increased significantly, as did the percentage of pan-drug-resistant isolates and resistant rates to most of antimicrobial agents; the percentage of drug-sensitive isolates decreased (all P < 0.05). The frequency of treatment with carbapenems and tigecycline increased, and that of cephalosporins decreased. Compared with those in the first years (2009-2012), ABCBSI patients in the lattermost years (2017-2018) were less often treated with appropriate empirical therapy, more often underwent pneumonia-related ABCBSI and mechanical ventilation support, and had higher 28-day mortality rates. Multivariate Cox regression indicated that increase in the degree of ABC antibiotics resistance, pneumonia-related ABCBSI, and septic shock were risk factors of 28-day mortality and associated with significant lower survival days. Conclusions: The past decade has witnessed a marked increase in the incidence of ABCBSI and in antibiotic resistance, with increasing pneumonia-related infections and worrisome mortality in ICUs in China. Controlling increasing resistance and preventing nosocomial pneumonia may play important roles in combatting these infections.

Systematic review and meta-analysis of the proportion and associated mortality of polymicrobial (vs monomicrobial) pulmonary and bloodstream infections by Acinetobacter baumannii complex

BACKGROUND

Differentiating Acinetobacter baumannii complex (ABC) infection from colonization remains difficult and further complicated in polymicrobial infections.

PURPOSE

To assess the frequency of polymicrobial ABC infections and associated mortality. We hypothesized a lower mortality in polymicrobial infections if ABC isolation reflects colonization in some polymicrobial infections.

METHODS

A systematic review was conducted in PubMed, Scopus and CENTRAL for studies reporting ABC pulmonary and bloodstream infections. The proportion of infections that were polymicrobial and the magnitude of the association between polymicrobial (vs monomicrobial) infection and mortality were estimated with meta-analyses.

RESULTS

Based on 80 studies (9759 infections) from 23 countries, the pooled proportion of polymicrobial infection was 27% (95% CI 22-31%) and was similarly high for bloodstream and pulmonary infections. Polymicrobial infection was variably and insufficiently defined in most (95%) studies. Considerable heterogeneity (I² = 95%) was observed that persisted in subgroup analyses and meta-regressions. Based on 17 studies (2675 infections), polymicrobial infection was associated with lower 28-day mortality (OR = 0.75, 95% CI 0.58-0.98, I² = 36%). However, polymicrobial infection was not associated with in-hospital mortality (OR = 0.97, 95% CI 0.69-1.35, I² = 0%) based on 14 studies (953 infections). The quality of evidence (GRADE) for the association of polymicrobial (vs monomicrobial) infection with mortality was low and at high risk of bias.

CONCLUSION

Polymicrobial ABC infections are common and may be associated with lower 28-day mortality. Considering the heterogeneity of polymicrobial infections and limitations of the available literature, more research is required to clarify the clinical impact of polymicrobial (vs monomicrobial) ABC infection.

Mapping Global Prevalence of Acinetobacter baumannii and Recent Vaccine Development to Tackle It

Acinetobacter baumannii is a leading cause of nosocomial infections that severely threaten public health. The formidable adaptability and resistance of this opportunistic pathogen have hampered the development of antimicrobial therapies which consequently leads to very limited treatment options. We mapped the global prevalence of multidrug-resistant A. baumannii and showed that carbapenem-resistant A. baumannii is widespread throughout Asia and the Americas. Moreover, when antimicrobial resistance rates of Acinetobacter spp. exceed a threshold level, the proportion of A. baumannii isolates from clinical samples surges. Therefore, vaccines represent a realistic alternative strategy to tackle this pathogen. Research into anti-A. baumannii vaccines have enhanced in the past decade and multiple antigens have been investigated preclinically with varying results. This review summarises the current knowledge of virulence factors relating to A. baumannii–host interactions and its implication in vaccine design, with a view to understanding the current state of A. baumannii vaccine development and the direction of future efforts.

Colonization With Extensively Drug-Resistant Acinetobacter baumannii and Prognosis in Critically Ill Patients: An Observational Cohort Study

Background: Acinetobacter baumannii is one of the most frequently isolated opportunistic pathogens in intensive care units (ICUs). Extensively drug-resistant A. baumannii (XDR-AB) strains lack susceptibility to almost all antibiotics and pose a heavy burden on healthcare institutions. In this study, we evaluated the impact of XDR-AB colonization on both the short-term and long-term survival of critically ill patients. Methods: We prospectively enrolled patients from two adult ICUs in Qilu Hospital of Shandong University from March 2018 through December 2018. Using nasopharyngeal and perirectal swabs, we evaluated the presence of XDR-AB colonization. Participants were followed up for 6 months. The primary endpoints were 28-day and 6-month mortality after ICU admission. The overall survival rate was estimated by the Kaplan-Meier method. We identified risk factors associated with 28-day and 6-month mortality using the logistic regression model and a time-dependent Cox regression model, respectively. Results: Out of 431 patients, 77 were colonized with XDR-AB. Based on the Kaplan-Meier curve results, the overall survival before 28 days did not differ by colonization status; however, a significantly lower overall survival rate was obtained at 6 months in colonized patients. Univariate and multivariate analysis results confirmed that XDR-AB colonization was not associated with 28-day mortality, but was an independent risk factor of lower overall survival at 6 months (HR = 1.749, 95% CI = 1.174-2.608). Conclusions: XDR-AB colonization has no effect on short-term overall survival, but is associated with lower long-term overall survival in critically ill patients.

Minocycline Alone and in Combination with Polymyxin B, Meropenem, and Sulbactam against Carbapenem-Susceptible and -Resistant Acinetobacter baumannii in an In Vitro Pharmacodynamic Model

Acinetobacter baumannii is recognized as an urgent public health threat by the Centers for Disease Control and Prevention (CDC). Current treatment options are scarce, particularly against carbapenem-resistant Acinetobacter baumannii (CRAB). We simulated the impact of minocycline standard (200 mg load + 100 mg Q12h) and high (700 mg load + 350 mg Q12h) doses, polymyxin B (2.5 mg/kg Q12h), sulbactam (1 g Q6h and 9 g/24 h as continuous infusion), and meropenem (intermittent 1 or 2 g Q8h and 6 g/24 h as continuous infusion) alone or in combination against CRAB and non-CRAB isolates by simulating human therapeutic dosing regimens in a 72-h, in vitro pharmacodynamic (IVPD) model. There were no monotherapy regimens that demonstrated bactericidal activity against the tested non-CRAB and CRAB strains. Resistance development was common in monotherapy regimens. Against the CRAB isolate, the triple combination of high-dose minocycline (fAUC/MIC 21.2), polymyxin B (fAUC/MIC 15.6), and continuous-infusion sulbactam (67% T _>MIC) was the most consistently active regimen. Against non-CRAB, the triple therapy regimen of high-dose minocycline (fAUC/MIC 84.8) with continuous-infusion meropenem (100% T _>MIC) and continuous-infusion sulbactam (83% T _>MIC), as well as the double therapy of high-dose minocycline (fAUC/MIC 84.8) with continuous-infusion meropenem (100% T _>MIC), resulted in persistently bactericidal activity. In conclusion, triple therapy with high-dose minocycline, continuous-infusion sulbactam, and polymyxin B produced the most significant kill against the carbapenem-resistant Acinetobacter baumannii, with no regrowth and minimal resistance development.

[Risk factors of nosocomial meningitis in neurological intensive care unit. Results of a five-year prospective study]

Nosocomial meningitis (NM) is a serious complication in neurosurgery. Understanding the risk factors of nosocomial meningitis is important for their prevention.

OBJECTIVE

To determine the main risk factors of NM in neurological intensive care unit.

MATERIAL AND METHODS

A prospective study included all patients (n=2140) treated at the neurological intensive care unit for more than 48 hours between October 1, 2010 and October 31, 2015. Cases of nosocomial meningitis were registered. We analyzed risk factors in 2 groups of patients (with and without NM).

RESULTS AND DISCUSSION

The incidence of NM in neurological intensive care unit was 8.4% (95% CI 6.8-10.0) (n=180). Relative risk of NM under external ventricular drainage was 3.98 (99 cases of NM, p<0.05). Relative risk of NM in patients with CSF leakage (including nasal CSF leakage after transsphenoidal surgery) was 5.2 (49 cases of NM, p<0.05). The incidence of nosocomial meningitis was significantly higher among patients with surgery time ≥8 hours (17.68%, p<0.01). Nosocomial meningitis was also significantly more common after redo surgery (13.07%, p<0.05). Insertion of intracranial pressure sensor was not a significant risk factor of NM. The risk of meningitis was 2.67% if the above-mentioned factors were absent. Extracranial factors are not specific for NM. No significant relationship between certain neurosurgical disease and NM was found.

CONCLUSION

We found higher risk of NM in ICU patients with the following factors: external ventricular drainage, CSF leakage, redo surgery and surgery time.

Investigation of carbapenem resistant Acinetobacter baumannii ST2 in Iran

This study investigated carbapenem resistance among Acinetobacter baumannii isolated from respiratory specimens. Epidemiological relationship of the isolates was also evaluated. In this study, 81 respiratory specimens of A. baumannii from AL Zahra Hospital were confirmed by phenotypic and genotypic methods. Antimicrobial susceptibility was performed by disc diffusion method. Carbapenem resistance genes were identified by PCR. The isolates were typed by RAPD-PCR and multilocus sequence typing (MLST) methods. All isolates were resistant to imipenem and 80 isolates to meropenem. Frequency of oxacillinase genes was as follows: blaOXA-23 gene was positive in 74 (91.3%), blaOXA-24 gene in 50 (61.7%) and blaOXA-58 was not found in any isolates. On the other hand 22 (27.2%) isolates contained blaIMP-1, 3 (3.7%) isolates contained blaIMP-2 gene, 5 (6.2%) isolates contained blaVIM-1, 4 (5%) isolates had blaVIM-2 and none of the isolates had blaSIM-1 gene. RAPD-PCR typing identified 16 different patterns, with one pattern being the most frequent one in 26 isolates. In MLST 6 different sequence types were identified, the most predominant being ST2 belonging to clonal complex 2. The results of this study showed high resistance to carbapenems as well as high abundance of oxacillinase genes.

[Evaluation of Hygiene in Dry Powder Steroid Drug Inhalers Used by Elderly Asthma Patients]

Dry powder inhalers (DPI) are frequently used by asthmatic patients, and the usage rate increases every year. The pharmacists at our hospital provided initial inhalation instructions on how the inhaler must be used but did not elaborate on the cleaning of the device. Therefore, the cleaning status of the inhaler is unknown, and there is a possibility of bacterial growth. This study investigated the cleaning status and hygiene of steroid drug inhalers used by elderly asthma patients. We administered a questionnaire to investigate the inhaler cleaning status after inhalation, and conducted a cross-sectional survey on hygiene using ATP measurement and bacterial culture examination. Considering the responses by 53 patients, it became clear that the ATP values of patients who answered "never cleaned" after inhalation were significantly higher than those who answered "cleaned every time". Moreover, some bacteria were detected in 62% of inhalers; 4 patients' inhalers contained bacteria other than normal oral microbial flora. In conclusion, because the inhalers used by elderly patients are in poor hygienic conditions, we must give cleaning instructions accordingly. We believe that it is necessary to give proper medical instructions along with instructions on the cleaning method with dry cloth.

Control and management of multidrug resistant Acinetobacter baumannii: A review of the evidence and proposal of novel approaches

Hospital-acquired infections are on the rise and are a substantial cause of clinical and financial burden for healthcare systems. While infection control plays a major role in curtailing the spread of outbreak organisms, it is not always successful. One organism of particular concern is Acinetobacter baumannii, due to both its persistence in the hospital setting and its ability to acquire antibiotic resistance. A. baumannii has emerged as a nosocomial pathogen that exhibits high levels of resistance to antibiotics, and remains resilient against traditional cleaning measures with resistance to Colistin increasingly reported. Given the magnitude and costs associated with hospital acquired infections, and the increase in multidrug-resistant organisms, it is worth re-evaluating our current approaches and looking for alternatives or adjuncts to traditional antibiotics therapies. The aims of this review are to look at how this organism is spread within the hospital setting, discuss current treatment modalities, and propose alternative methods of outbreak management.

The effect of temporary closure and enhanced terminal disinfection using aerosolized hydrogen peroxide of an open-bay intensive care unit on the acquisition of extensively drug-resistant Acinetobacter baumannii

Background

At Makassed Hospital’s open-bay intensive care unit (ICU), enhanced terminal disinfection (ETD) using hydrogen peroxide (H₂O₂) was performed without a predefined schedule in extensively-drug-resistant Acinetobacter baumannii (XDR-AB) outbreaks. In this study, we aimed to check for the value of the temporary closure of the ICU and the use of ETD with aerosolized H₂O₂ and Ag⁺ on minimizing the rate of XDR-AB acquisition in patients admitted to the ICU of our facility, which might consequently help us determine the optimal schedule for such procedure in this unit.

Methods

This is a retrospective medical file review of patients admitted to the ICU between January 2016 and May 2018. We divided this period into numerical weeks (NW) after each closure and ETD episode. Risk factors of acquisition (RFA) were determined by comparing the characteristics of patients who acquired XDR-AB to those who didn’t. The proportion of patients residing in each NW was included in the RFA analysis.

Results

Out of 335 patients, 13% acquired XDR-AB. The overall incidence of XDR-AB acquisition was 14.6 cases/1000 patient days. RFA were XDR-AB contact pressure ≥ 3 days [Odds Ratio (OR) = 9.86, 95% Confidence Interval (CI) (3.65–26.64), P < 0.0001)], mechanical ventilation [OR = 4.99, 95%CI (1.76–14.15), P = 0.002)], and having a wound [OR = 3.72, 95%CI (0.99–13.96), P = 0.05)]. Patients who stayed during NW 7,11 and 14 were at risk of acquisition where the odds significantly increased by 6.5, 9.7 and 14.4 folds respectively (P = 0.03,0.01, and 0.01, respectively). We considered NW 7 as the most suitable time for temporary closure of the ICU and ETD with aerosolized H₂O₂.

Conclusion

Contact pressure, mechanical ventilation, and presence of a wound were RFA of XDR-AB. Temporary closure of the ICU with ETD using aerosolized H₂O₂ decreased the rate of XDR-AB acquisition, yet this effect fades away with time. The ETD was shown to be most efficiently done when repeated every 7 calendar weeks in our open-bay ICU as part of a prevention bundle.

The first nationwide multicenter study of Acinetobacter baumannii recovered in Serbia: emergence of OXA-72, OXA-23 and NDM-1-producing isolates

Background

The worldwide emergence and clonal spread of carbapenem-resistant Acinetobacter baumannii (CRAB) is of great concern. The aim of this nationwide study was to investigate the prevalence of CRAB isolates in Serbia and to characterize underlying resistance mechanisms and their genetic relatedness.

Methods

Non-redundant clinical samples obtained from hospitalized patients throughout Serbia were included in the prospective, observational, multicenter study conducted from January to June 2018. Samples were initially screened for the presence of Acinetobacter baumannii-calcoaceticus (Acb) complex using conventional bacteriological techniques. Acb complexes recovered from clinical samples obtained from inpatients with confirmed bacterial infections were further evaluated for the presence of A. baumannii. Identification to the species level was done by the detection of the bla_OXA-51 gene and rpoB gene sequence analysis. Susceptibility testing was done by disk diffusion and broth microdilution method. CRAB isolates were tested for the presence of acquired carbapenemases (bla_OXA-24-like, bla_OXA-23-like,bla_OXA-58-like, bla_OXA-143-like, bla_IMP, bla_VIM, bla_GIM, bla_SPM, bla_SIM, bla_NDM) by PCR. Clonal relatedness was assessed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).

Results

Acb complex was isolated in 280 out of 2401 clinical samples (11.6%). Overall, A. baumannii was identified in 237 out of 280 Acb complex (84.6%). CRAB prevalence was found to be 93.7% (237/222). The MIC₅₀/MIC₉₀ for imipenem and meropenem were 8/> 32 μg/mL and 16/> 32 μg/mL, respectively. Although susceptibility was high for colistin (95.7%; n = 227) and tigecycline (75.1%; n = 178), ten isolates (4.3%) were classified as pandrug-resistant. The following carbapenemases-encoding genes were found: 98 (44.2%) bla_OXA-24-like, 76 (34.5%) bla_OXA-23-like, and 7 (3.2%) bla_NDM-1. PFGE analysis revealed six different clusters. MLST analysis identified three STs: ST2 (n = 13), ST492 (n = 14), and ST636 (n = 10). Obtained results evaluated that circulating CRAB clones in Serbia were as follows: bla_OXA66/bla_OXA23/ST2 (32.4%), bla_OXA66/bla_OXA23/bla_OXA72/ST2 (2.7%), bla_OXA66/bla_OXA72/ST492 (37.8%), and bla_OXA66/bla_OXA72/ST636 (27.1%).

Conclusion

This study revealed extremely high proportions of carbapenem resistance among A. baumannii clinical isolates due to the emergence of bla_OXA-72, bla_OXA-23, and bla_NDM-1 genes among CRAB isolates in Serbia and their clonal propagation.

Dynamics of the lung microbiome in intensive care patients with chronic obstructive pulmonary disease and community-acquired pneumonia

Little is known about the composition and clinical implications of lung microbiome in patients with chronic obstructive pulmonary disease (COPD) and community-acquired pneumonia requiring invasive mechanical ventilation and intensive care unit admission. Therefore, this study aimed to explore the longitudinal changes in microbial airway composition and its variations between COPD patients with different weaning outcomes. Fifty-one endotracheal aspirate samples from 21 participants and 5 saline samples were collected as the patient and control group, respectively. Sequence analysis revealed significant increases and upward trends in the relative abundance of the Acinetobacter genus and Acinetobacter baumannii complex species in paired comparisons of sampling points and over time, respectively, in patients with failed weaning (p for trend = 0.012 and 0.012, respectively) but not in those with successful weaning (p for trend = 0.335 and 0.426, respectively). Furthermore, significant changes in the composition of the bacterial community were observed in paired comparisons of sampling points in patients with failed weaning compared with those with successful weaning. The alpha diversity did not differ between the patients with different weaning outcomes. These results further the understanding of longitudinal airway microbiome structure analysis and its clinical implications when managing critically ill patients with and without COPD.

Low-temperature laminar flow ward for the treatment of multidrug resistance Acinetobacter baumannii pneumonia

This study was designed to investigate the effect of low-temperature laminar flow ward (LTLFW) on the Acinetobacter baumannii pneumonia (MDR-ABP) in neurosurgical intensive care unit (NICU) patients. We evaluated whether patients in a LTLFW had significantly improved clinical outcomes as compared to those in nonconstant-temperature NICU (room temperature). The association of temperature with the prevalence of ABP and A. baumannii isolates (ABI) found in NICU patients was specifically investigated. In vitro microbiological experiments were conducted to measure the proliferation, antibiotic sensitivity, and genomic profiles of A. baumannii (AB) that grew in variable temperatures. MDR-ABP patients in LTLFW had significantly improved outcomes than those in the room temperature NICU. In addition, the numbers of ABI were positively associated with mean ambient outdoor temperatures (P = 0.002), with the incidence of ABP and average numbers of ABI among NICU patients being substantially lower in the winter as compared to other seasons. However, there were no significant seasonal variations in the other strains of the top five bacteria. Consistent with these clinical observations, AB growing at 20°C and 25°C had significantly reduced viability and antibiotic resistance compared to those growing at 35°C. The expression of genes related to AB survival ability, drug resistance, and virulence also differed between AB growing at 20°C and those at 35°C. LTLFW is effective in promoting the recovery of MDR-ABP patients because low temperatures reduced the density and virulence of AB and enhanced the efficacy of antibiotics, likely at the genetic level.

Hyper-expression of the efflux pump gene adeB was found in Acinetobacter baumannii with decreased triclosan susceptibility

OBJECTIVES

Triclosan is usually employed as a disinfectant in a wide range of medical and consumer care products, which may have imposed a selective pressure on bacteria. This study was designed to evaluate the resistance mechanisms of triclosan and molecular epidemiology of triclosan-resistant isolates of Acinetobacter baumannii in Wenzhou, China.

METHODS

A collection of 626 A. baumannii were isolated from the First Affiliated Hospital of Wenzhou Medical University during 2016-2017 and antimicrobial susceptibility testing of these isolates were performed via agar dilution method. Molecular mechanisms of triclosan resistance, including the existence of mutations in reductase (FabI) were investigated by PCR and sequencing. Furthermore, quantitative RT-PCR was conducted to evaluate the expression levels of the fabI gene and efflux pump genes (adeB, adeG, adeJ, abeM, amvA and abeS) at normal condition and sub-inhibitory concentration of triclosan, and the epidemiological characteristics were analyzed by PFGE and MLST.

RESULTS

2.7% (17/626) of A. baumannii exhibited resistance to triclosan. The FabI mutation Gly95Ser was found in one triclosan resistant strain. The expression of fabI and adeB gene were significant difference between triclosan-resistant and susceptible strains (P < 0.05). The expression of fabI, adeG, adeJ and abeM were increased after triclosan induction. The clones of these resistant isolates were diverse and sporadic.

CONCLUSIONS

The hyper-expression of fabI was probably the main mechanism of triclosan resistance in this study, and the efflux pump AdeB, AdeG, AdeJ and AbeM might also be related to decreased triclosan susceptibility.

Pattern of antimicrobial resistance of Gram-negative bacilli in surgical site infections in in-patients and out-patients at an apex trauma Center: 2013-2016

INTRODUCTION:

Antimicrobial resistance is an increasing problem worldwide especially among the surgical site infections (SSIs). SSI is becoming more serious due to hospital-acquired infections/nosocomial infections, which further leads to the overuse of broad-spectrum antibiotics. To investigate the antimicrobial resistance patterns among Gram-negative bacteria in SSI in in- and out-patients the present study was designed.

METHODOLOGY:

During the 4 years (January 2013–December 2016), the antimicrobial resistant pattern was studied in the admitted patients and in the patients who were followed up to the outpatients department (OPD) after discharge. Antimicrobial resistance pattern testing was done by the disk diffusion method on Mueller-Hinton agar and by E-test for ten antibiotics according to The Clinical and Laboratory Standards Institute guidelines for Gram-negative bacilli.

RESULTS:

A total of 2,447 strains were isolated from the studied population on over the period of 4 years. Of 2447, 1996 (81%) were isolated from patients who had SSI during the hospital stay, and 451 (18%) were from patients who attended the OPD after discharge. In the outpatients, who followed up in the OPD for the SSI, Escherichia coli (148), and Pseudomonas aeruginosa (93), whereas in the patients who develop SSI during their hospital stay, Acinetobacter baumannii (622), E. coli (424), and Klebsiella pneumoniae (315) were found to be common. A very high resistance pattern was observed in both the studied groups; however, a higher resistance pattern was seen in in-patients as compared to outpatients.

CONCLUSION:

In our study, we have reported resistance pattern in Gram-negative bacteria isolated from the patients who were came for the follow as well as in the inpatients. For the outpatients, it can be concluded that it could be a community-acquired infection which is also an alarming condition for our society.

A Study of Multidrug-Resistant, Colistin-Only-Sensitive Infections in Intubated and Mechanically Ventilated Patients Over 2 Years

Background and Aims

Multidrug-resistant, Gram-negative infections are increasingly common in the intensive care unit (ICU). This study compares the occurrence and outcome of colistin-only-sensitive (COS) infections among mechanically ventilated patients at a tertiary hospital ICU.

Methods

The study included adult patients admitted over a period of 2 years, who were intubated and mechanically ventilated for more than 48 h. They were divided into two groups, those with COS infections and those without, and their GCS and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, ICU length of stay, leukocyte count, and mortality were compared. COS patients were divided into neurosurgery, neurology, respiratory, and sepsis with bacteremia groups. The COS organisms in each group, their sources, ICU length of stay, ventilator-free days, and mortality were analyzed.

Results

Three hundred and one patients were selected, of whom 41 (13.6%) had COS infections. COS patients had a longer ICU length of stay than non-COS patients (P = 0.001) but comparable APACHE II and GCS scores, leukocyte count, and mortality. The sepsis group accounted for 8 out of 15 (53%) deaths among COS patients (P = 0.03). Acinetobacter baumannii accounted for 61% of the COS infections, Klebsiella pneumonia: 24.4%, Pseudomonas aeruginosa: 12.2%, and Escherichia coli: 2.4%. Endotracheal secretion cultures accounted for 65.8% of COS isolates, urine cultures 17%, pus cultures 7.3%, and blood cultures 4.9%. ICU length of stay, ventilator-free days, and mortality were similar between each COS organism.

Conclusion

Intubated patients with multidrug-resistant, COS infections have a longer stay in ICU than non-COS patients. COS infections associated with bacteremia have high mortality.

Toward a structome of Acinetobacter baumannii drug targets

Acinetobacter baumannii is well known for causing hospital-associated infections due in part to its intrinsic antibiotic resistance as well as its ability to remain viable on surfaces and resist cleaning agents. In a previous publication, A. baumannii strain AB5075 was studied by transposon mutagenesis and 438 essential gene candidates for growth on rich-medium were identified. The Seattle Structural Genomics Center for Infectious Disease entered 342 of these candidate essential genes into our pipeline for structure determination, in which 306 were successfully cloned into expression vectors, 192 were detectably expressed, 165 screened as soluble, 121 were purified, 52 crystalized, 30 provided diffraction data, and 29 structures were deposited in the Protein Data Bank. Here, we report these structures, compare them with human orthologs where applicable, and discuss their potential as drug targets for antibiotic development against A. baumannii.

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.

Mortality from acinetobacter infections as compared to other infections among critically ill patients in South India: A prospective cohort study

Background

Acinetobacter baumannii has become a common pathogen causing hospital-acquired infections (HAIs). Although acquiring any nosocomial infection is associated with increased mortality, we do not know if the acquisition of Acinetobacter infection confers a worse prognosis as compared to non-Acinetobacter-related HAI. The aim of the current study is to compare the clinical outcomes of ventilator-associated pneumonia (VAP) and central line associated blood stream infections (CLABSIs) caused by A. baumannii with those caused by other bacterial pathogens.

Materials and Methods

This prospective cohort study was conducted among critically ill adults admitted to a tertiary care hospital in South India from January 2013 to June 2014. We enrolled patients who developed new-onset fever ≥48 h after admission and fulfilled pre-specified criteria for VAP or CLABSI. The patients were followed up until the primary outcomes of death or hospital discharge.

Results

During the study period, 4047 patients were admitted in the intensive care units, among which 129 eligible HAI events were analysed. Of these, 95 (73.6%) were VAP, 34 (26.4%) were CLABSI, 78 (60.4%) were A. baumannii-related HAI (AR-HAI) and 51 (39.6%) were non-A. baumannii-related HAI (NAR-HAI). Mortality among AR-HAI was 57.6% compared to 39.2% in NAR-HAI (P = 0.04) which on multivariate analysis did not achieve statistical significance, although the trend persisted (odds ratio [OR] = 4.2, 95% confidence interval [CI]: 0.95-18.4, P = 0.06). The acquisition of VAP due to A. baumannii was associated with poor ventilator outcomes even after adjusting for confounders (adjusted OR = 3.5, 95% CI: 1.07-11.6, P = 0.04).

Conclusion

In our cohort of critically ill adults with VAP and CLABSI, AR-HAI was associated with poor ventilator outcomes and a trend towards higher mortality. These findings add to the evidence suggesting that A. baumannii is a dangerous pathogen, perhaps even more so than others.

Upregulation of the clpB gene in response to heat shock and beta-lactam antibiotics in Acinetobacter baumannii

The role of the clpB gene encoding HSP/chaperone ClpB was evaluated in the multiresistant antibiotic cells of Acinetobacter baumannii (RS4 strain) under stress-induced heat shock and different beta-lactams. The expression of the clpB gene was assessed by qPCR during heat shock at 45 °C and subinhibitory concentrations of ampicillin (30 μg mL^-1), amoxicillin + sulbactam (8/12 μg mL^-1), cefepime (30 μg mL^-1), sulfamethoxazole + trimethoprim (120/8 μg mL^-1) and meropenem (18 μg mL^-1). The results indicated a transient increase in clpB transcription in all treatments except cefepime. Both in the presence of ampicillin and amoxicillin/sulbactam for 20 min, the mRNA-clpB synthesis was 1.4 times higher than that of the control at time zero. Surprisingly, the mRNA-clpB levels were more than 30-fold higher after 10 min of incubation with meropenem and more than eightfold higher in the presence of trimethoprim/sulfamethoxazole. In addition, western blot assays showed that the RS4 strain treated with meropenem showed a marked increase in ClpB protein expression. Our data indicate that during exposure to beta-lactams, A. baumannii adjusts the transcription levels of the clpB mRNA and protein to respond to stress, suggesting that the chaperone may act as a key cellular component in the presence of antibiotics in this bacterium.

The global prevalence of multidrug-resistance among Acinetobacter baumannii causing hospital-acquired and ventilator-associated pneumonia and its associated mortality: A systematic review and meta-analysis

OBJECTIVE

The objective of this works was to assess the global prevalence of multidrug-resistance among A. baumannii causing hospital-acquired (HAP) and ventilator-associated pneumonia (VAP), and describe its associated mortality.

METHODS

We performed a systematic search of four databases for relevant studies. Meta-analysis was done based on United Nations geoscheme regions, individual countries and study period. We used a random-effects model to calculate pooled prevalence and mortality estimates with 95% confidence intervals (CIs), weighted by study size.

RESULTS

Among 6445 reports screened, we identified 126 relevant studies, comprising data from 29 countries. The overall prevalence of multidrug-resistance among A. baumannii causing HAP and VAP pooled from 114 studies was 79.9% (95% CI 73.9-85.4%). Central America (100%) and Latin America and the Caribbean (100%) had the highest prevalence, whereas Eastern Asia had the lowest (64.6%; 95% CI, 50.2-77.6%). The overall mortality estimate pooled from 27 studies was 42.6% (95% CI, 37.2-48.1%).

CONCLUSIONS

We observed large amounts of variation in the prevalence of multidrug-resistance among A. baumannii causing HAP and VAP and its mortality rate among regions and lack of data from many countries. Data from this review can be used in the development of customized strategies for infection control and antimicrobial stewardship.

Epidemiological investigation of non-fermentative bacterial infection in cirrhotic patients

Background: This study aimed to describe the clinical characteristics of NFGNB in patients with cirrhosis as well as the risk factors for short-term mortality. Methods: A retrospective analysis was performed in patients with cirrhosis and NFGNB infections from 2011 to 2016 . Results: 144 episodes in 134 patients with liver cirrhosis and NFGNB infections were found in total. Of these, 81.2% were hospital-acquired or healthcare- associated infections, while only 18.8% of NFGNB infections originated from the community. A. baumannii were the most frequently isolated bacteria (39 episodes), followed by S. maltophilia (38 episodes) and P. aeruginosa (31 episodes). MDR- and non-MDR-NFGNB comprised 62.5% and 37.5% of infections respectively. The Kaplan-Meier survival curve showed no significant difference between MDR and non-MDR NFGNB patients (74.1% vs 75.5%, P = 0.811). Neither MDR or the subgroup of common NFGNB (P. aeruginosa, A. baumannii, S. maltophilia) was associated with the 28-day mortality (all P >0.05). Low albumin levels and high Tbil levels were both independent risk factors for 28-day mortality (HR = 0.930, 95%CI (0.869, 0.995), P = 0.035; HR = 1.003, 95%CI (1.002, 1.005), P < 0.001, respectively). Conclusions: Diabetes increased 28-day mortality significantly, however, MDR status, site of infection and bacteria type did not.

DNA vaccine encoding OmpA and Pal from Acinetobacter baumannii efficiently protects mice against pulmonary infection

Acinetobacter baumannii (A. baumannii) is an opportunistic pathogen that causes serious infections in the lungs, blood, and brain in critically ill hospital patients, resulting in considerable mortality rates every year. Due to the rapid appearance of multi-drug resistance or even pan-drug resistance isolates, it is becoming more and more difficult to cure A. baumannii infection by traditional antibiotic treatment, alternative strategies are urgently required to combat A. baumannii infection. In this study, we developed a DNA vaccine encoding two antigens from A. baumannii, OmpA and Pal, and the immunogenicity and protective efficacy was further evaluated. The results showed that the DNA vaccine exhibited significant immune protective efficacy against acute A. baumannii infection in a mouse pneumonia model, and cross protective efficacy was observed when immunized mice were challenged with clinical strains of A. baumannii. DNA vaccine immunization induced high level of humoral response and a mixed Th1/Th2/Th17 cellular response, which protect against lethal bacterial challenges by decreased bacterial loads and pathology in the lungs, and reduced level of inflammatory cytokines expression and inflammatory cell infiltration in BALF. These results demonstrated that it is possible to prevent A. baumannii infection by DNA vaccine and both OmpA and Pal could be serve as promising candidate antigens.

Antibiotic resistance profile and co-production of extended spectrum beta lactamases and AmpC in Acinetobacter spp. in a level 1 trauma center from India

INTRODUCTION:

Acinetobacter baumannii has now emerged as a significant nosocomial pathogen in health-care setting ESP in intensive care units. Rapidly growing resistance among clinical isolates suggests a need to detect resistance mechanisms in this organism. The present study was designed to compare the various phenotypic tests available with the gold standard of genotype.

METHODOLOGY:

The present study was conducted to include all isolates of Acinetobacter spp. isolated over 3 years. Their resistance to various antibiotics was determined and extended spectrum beta-lactamases (ESBL) and AmpC production in the isolates showing resistance to ceftazidime/ceftriaxone/cefotaxime (CAZ/CTR/CTX) was determined. ESBL and AmpC production was confirmed using polymerase chain reaction (PCR).

RESULTS:

A total of 154 strains were isolated, and all the strains were tested for ESBL and AmpC detection. Of the strains tested, 15 (9.7%), 17 (11%), 24 (15.6%), 27 (17.5%), 54 (35%), 67 (43.5%), and 72 (46.7%) strains showed ESBL production using CTX/CTX-clavulanate double-disc synergy test (DDST), CTX/CTX-clavulanate E-test, CAZ/CAZ-clavulanate DDST, CAZ/CAZ-clavulanate E-test, Piperacillin/Piperacillin-tazobactam (TZ) DDST, CTR/CTR-Sulbactum DDST, and Piperacillin/Piperacillin-TZ E-test, respectively. 20 (12.9%) and 19 (12.3%) of strains were positive for AmpC production using AmpC disc test and Boronic acid inhibition test, respectively. Genotype analysis using PCR for TEM, SHV, CTXM, PER, and VEB genes was done and 69 (51.5%) strains were positive for TEM gene.

DISCUSSION:

ESBL detection in Acinetobacter spp. is difficult as standard guidelines for the same are not available unlike in enterobacteriaceae, and there are no zone diameter breakpoints for aztreonam and cefpodoxime. In comparison, piperacillin/piperacillin-TZ E-test had the best sensitivity and specificity for ESBL detection.

CONCLUSION:

Standard guidelines for ESBL detection in nil fermeners like Acinetobacter spp. must be laid down for ease of detection. Use of piperacillin/piperacillin-tazobactam E-test could be used as one of the standard methods.

Characteristics of pathogens and mortality predictors of older Chinese patients with nosocomial urinary tract infections

AIM

The aim of the present study was to investigate predominant pathogens and predictors of 28-day mortality of older Chinese patients with nosocomial urinary tract infections (NUTI).

METHODS

We retrospectively studied 1122 older patients (aged ≥60 years) with culture-positive NUTI in Guangdong General Hospital, Guangzhou, China, from January 2009 to December 2014. The clinical features, microbial distributions and outcomes of these patients were recorded and compared between survival and death patients. Multivariate logistic regression was carried out to identify independent predictors of 28-day mortality.

RESULTS

The present results showed the all-cause mortality was 8.3%, and NUTI mortality was 1.43%. The proportions of Candida albicans (P = 0.004), Acinetobacter baumannii (P = 0.045) and Candida tropicalis (P < 0.001) in the death group were significantly higher than those in the survival group. Multivariate analysis showed two novel risk factors for mortality of older patients with NUTI, which were higher Charlson Comorbidity Index (odds ratio [OR] 1.205, 95% confidence interval (CI) 1.088-1.334] and lower level of serum prealbumin (OR 0.995, 95% CI 0.990-0.999). Furthermore, previous use of antibiotics (OR 1.984, 95% CI 1.106-3.559), inappropriate antimicrobial therapy (OR 1.883, 95% CI 1.144-3.098), intensive care unit stay (OR 4.082, 95% CI 2.469-6.749) and higher concentration of serum C-reactive protein (OR 1.005, 95% CI 1.001-1.010) were independent prognostic factors for 28-day mortality in older patients with NUTI.

CONCLUSIONS

NUTI is associated with a high 28-day in-hospital mortality rate in older patients. We should evaluate the comorbidity, nutritional status, inflammatory markers, department staying and drug sensitivity test, and choose systematic therapy strategies for these older patients with NUTI. Geriatr Gerontol Int 2019; 19: 541-546.

The Role of Minocycline in the Treatment of Nosocomial Infections Caused by Multidrug, Extensively Drug and Pandrug Resistant Acinetobacter baumannii: A Systematic Review of Clinical Evidence

Treatment options for multidrug resistant Acinetobacter baumannii strains (MDR-AB) are limited. Minocycline has been used alone or in combination in the treatment of infections associated with AB. A systematic review of the clinical use of minocycline in nosocomial infections associated with MDR-AB was performed according to the PRISMA-P guidelines. PubMed-Medline, Scopus and Web of Science ^TM databases were searched from their inception until March 2019. Additional Google Scholar free searches were performed. Out of 2990 articles, 10 clinical studies (9 retrospective case series and 1 prospective single center trial) met the eligibility criteria. In total, 223 out of 268 (83.2%) evaluated patients received a minocycline-based regimen; and 200 out of 218 (91.7%) patients with available data received minocycline as part of a combination antimicrobial regimen (most frequently colistin or carbapenems). Pneumonia was the most common infection type in the 268 cases (80.6% with 50.4% ventilator-associated pneumonia). The clinical and microbiological success rates following minocycline treatment were 72.6% and 60.2%, respectively. Mortality was 20.9% among 167 patients with relevant data. In this systematic review, minocycline demonstrated promising activity against MDR-AB isolates. This review sets the ground for further studies exploring the role of minocycline in the treatment of MDR-AB associated infections.

Acinetobacter baumannii infection in a medical intensive care unit: The impact of strict infection control

Background

Acinetobacter baumannii is a waterborne organism that preferentially colonises aquatic environments. Infections usually involve organ systems that have a high fluid content. Multidrug-resistant (MDR) A. baumannii is recognised to be among the most difficult antimicrobial-resistant Gram-negative bacilli to prevent and treat in the nosocomial setting.

Objectives

To determine the utility of concomitant implementation of a strict antimicrobial stewardship programme and comprehensive infection control measures to control MDR A. baumannii in a medical intensive care unit (ICU).

Methods

We retrospectively compared the relative incidence of A. baumannii infections in our unit over a 1-year period before (2012) and after (2016) the implementation of strict infection control bundles. Patients with A. baumannii infections were identified using the microbiology database of the National Health Laboratory Service's central data warehouse. The total number of admissions and clinical data were derived from the ICU registry.

Results

A. baumannii was isolated from 43/263 patients (16.35%) in 2012 compared with 37/348 patients in 2016 (10.63%, p=0.03; relative risk reduction=35%). We found almost 100% sensitivity to colistin and tigecycline, but 90% resistance to carbapenem antibiotics.

Conclusion

The introduction of strict infection control bundles had a statistically significant and clinically meaningful impact on the incidence of nosocomial A. baumannii infection in the medical ICU.

Impact of an Acinetobacter baumannii outbreak on kidney events in a burn unit: A targeted machine learning analysis

BACKGROUND

Multidrug-resistant (MDR) bacteria outbreaks represent a major threat in intensive care units. Patients may then be exposed to drug-related direct toxicity during such outbreaks. The objective of this study was to explore the impact of an outbreak of imipenem-resistant Acinetobacter baumannii (IR-AB) on renal outcomes.

METHODS

We performed a before-and-after observational study in a French burn intensive care unit during an IR-AB outbreak: a 13-month period before (period A, October 2013-October 2014) and a 13-month period after outbreak control (period B, December 2014-December 2015). A total of 409 patients were included, 195 during period A and 214 during period B. The main endpoint was major adverse kidney events at day 90 (MAKE 90). Secondary endpoints were acute kidney injury (AKI) and persistent renal dysfunction.

RESULTS

Incidence of MAKE 90 was 15.9% during period A versus 11.2% during period B (P = .166) and AKI 28.2% versus 18.7% (P = .023). The use of colistin was associated with renal outcomes in univariate analysis. After adjustment of potential confounding factors using a targeted Machine Learning Analysis (ie, IR-AB-related infection, septic shock, severity scores, other nephrotoxics, chronic kidney disease, serum creatinine at admission, Staphylococcus aureus), colistin remained associated with the risk of MAKE and AKI (relative risk = 2.909, 95% confidence interval [CI] [1.364, 6.204], P = .006 for MAKE 90, and relative risk = 2.14, 95% CI [1.52, 3.02], P<.0001 for AKI).

CONCLUSIONS

The episode of IR-AB outbreak was associated with an increased risk of kidney events, which appears to be driven by the use of colistin.

Carbapenem-Nonsusceptible Acinetobacter baumannii, 8 US Metropolitan Areas, 2012-2015

In healthcare settings, Acinetobacter spp. bacteria commonly demonstrate antimicrobial resistance, making them a major treatment challenge. Nearly half of Acinetobacter organisms from clinical cultures in the United States are nonsusceptible to carbapenem antimicrobial drugs. During 2012–2015, we conducted laboratory- and population-based surveillance in selected metropolitan areas in Colorado, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon, and Tennessee to determine the incidence of carbapenem-nonsusceptible A. baumannii cultured from urine or normally sterile sites and to describe the demographic and clinical characteristics of patients and cases. We identified 621 cases in 537 patients; crude annual incidence was 1.2 cases/100,000 persons. Among 598 cases for which complete data were available, 528 (88.3%) occurred among patients with exposure to a healthcare facility during the preceding year; 506 (84.6%) patients had an indwelling device. Although incidence was lower than for other healthcare-associated pathogens, cases were associated with substantial illness and death.

Metabolic Responses to Polymyxin Treatment in Acinetobacter baumannii ATCC 19606: Integrating Transcriptomics and Metabolomics with Genome-Scale Metabolic Modeling

Multidrug-resistant (MDR) Acinetobacter baumannii has emerged as a very problematic pathogen over the past decades, with a high incidence in nosocomial infections. Discovered in the late 1940s but abandoned in the 1970s, polymyxins (i.e., polymyxin B and colistin) have been revived as the last-line therapy against Gram-negative "superbugs," including MDR A. baumannii. Worryingly, resistance to polymyxins in A. baumannii has been increasingly reported, urging the development of novel antimicrobial therapies to rescue this last-line class of antibiotics. In the present study, we integrated genome-scale metabolic modeling with multiomics data to elucidate the mechanisms of cellular responses to colistin treatment in A. baumannii. A genome-scale metabolic model, iATCC19606, was constructed for strain ATCC 19606 based on the literature and genome annotation, containing 897 genes, 1,270 reactions, and 1,180 metabolites. After extensive curation, prediction of growth on 190 carbon sources using iATCC19606 achieved an overall accuracy of 84.3% compared to Biolog experimental results. Prediction of gene essentiality reached a high accuracy of 86.1% and 82.7% compared to two transposon mutant libraries of AB5075 and ATCC 17978, respectively. Further integrative modeling with our correlative transcriptomics and metabolomics data deciphered the complex regulation on metabolic responses to colistin treatment, including (i) upregulated fluxes through gluconeogenesis, the pentose phosphate pathway, and amino acid and nucleotide biosynthesis; (ii) downregulated TCA cycle and peptidoglycan and lipopolysaccharide biogenesis; and (iii) altered fluxes over respiratory chain. Our results elucidated the interplay of multiple metabolic pathways under colistin treatment in A. baumannii and provide key mechanistic insights into optimizing polymyxin combination therapy. IMPORTANCE Combating antimicrobial resistance has been highlighted as a critical global health priority. Due to the drying drug discovery pipeline, polymyxins have been employed as the last-line therapy against Gram-negative "superbugs"; however, the detailed mechanisms of antibacterial killing remain largely unclear, hampering the improvement of polymyxin therapy. Our integrative modeling using the constructed genome-scale metabolic model iATCC19606 and the correlative multiomics data provide the fundamental understanding of the complex metabolic responses to polymyxin treatment in A. baumannii at the systems level. The model iATCC19606 may have a significant potential in antimicrobial systems pharmacology research in A. baumannii.

Sepsis in Intensive Care Unit Patients: Worldwide Data From the Intensive Care over Nations Audit

Background

There is a need to better define the epidemiology of sepsis in intensive care units (ICUs) around the globe.

Methods

The Intensive Care over Nations (ICON) audit prospectively collected data on all adult (>16 years) patients admitted to the ICU between May 8 and May 18, 2012, except those admitted for less than 24 hours for routine postoperative surveillance. Data were collected daily for a maximum of 28 days in the ICU, and patients were followed up for outcome data until death, hospital discharge, or for 60 days. Participation was entirely voluntary.

Results

The audit included 10069 patients from Europe (54.1%), Asia (19.2%), America (17.1%), and other continents (9.6%). Sepsis, defined as infection with associated organ failure, was identified during the ICU stay in 2973 (29.5%) patients, including in 1808 (18.0%) already at ICU admission. Occurrence rates of sepsis varied from 13.6% to 39.3% in the different regions. Overall ICU and hospital mortality rates were 25.8% and 35.3%, respectively, in patients with sepsis, but it varied from 11.9% and 19.3% (Oceania) to 39.5% and 47.2% (Africa), respectively. After adjustment for possible confounders in a multilevel analysis, independent risk factors for in-hospital death included older age, higher simplified acute physiology II score, comorbid cancer, chronic heart failure (New York Heart Association Classification III/IV), cirrhosis, use of mechanical ventilation or renal replacement therapy, and infection with Acinetobacter spp.

Conclusions

Sepsis remains a major health problem in ICU patients worldwide and is associated with high mortality rates. However, there is wide variability in the sepsis rate and outcomes in ICU patients around the globe.

Retrospective comparative analysis of risk factors and outcomes in patients with carbapenem-resistant Acinetobacter baumannii bloodstream infections: cefoperazone-sulbactam associated with resistance and tigecycline increased the mortality

Background

Carbapenem-resistant Acinetobacter baumannii (CRAB) is a rapidly emerging, life-threatening nosocomial infection. This study aimed to explore the risk factors, clinical features, antimicrobial therapy, and outcomes of CRAB bloodstream infections (BSIs).

Methods

This is a retrospective, comparative analysis of data from patients with A. baumannii BSI, treated from 2012 to 2015 at a tertiary teaching hospital. Risk factors associated with CRAB BSI and factors associated with the 28-day mortality were evaluated using logistic analyses.

Results

Data from 293 patients with confirmed A. baumannii BSI were included; 242 (82.6%) patients had CRAB BSI and 51 (17.4%) patients had non-CRAB BSI. Risk factors significantly associated with CRAB BSI were a previous intensive care unit (ICU) stay (P=0.029), cefoperazone–sulbactam use (P=0.030), and carbapenem use (P=0.004). Among 236 patients with A. baumannii BSI who were evaluable at 28 days after receiving antibacterial therapy, there were 86 deaths. Factors associated with the 28-day mortality were ICU stay after BSI (P=0.040), readmission within 90 days (P=0.029), Acute Physiology and Chronic Health Evaluation II (APACHE II) score at diagnosis >19 (P=0.012), tigecycline therapy (P=0.021), presence of septic shock (P=0.029), and multiple organ failure (P=0.016). Death rates in patients treated with tigecycline were 53.5% vs 24.1% in patients treated with other agents. Among 186 patients with CRAB BSI evaluable at 28 days, 84 patients died. The associated risk factors were an ICU stay after BSI (P=0.036), APACHE II score >19 at diagnosis (P = 0.002), presence of septic shock (P=0.030), and multiple organ failure (P=0.007).

Conclusion

This study demonstrated that an ICU stay and cefoperazone–sulbactam or carbapenem use were seen to be the risk factors associated with the development of CRAB BSI. Critical illness and tigecycline therapy were significantly associated with higher mortality of patients with A. baumannii BSI.