Risk factors for nosocomial imipenem-resistant Acinetobacter baumannii infections

Development and application of a risk nomogram for the prediction of risk of carbapenem-resistant Acinetobacter baumannii infections in neuro-intensive care unit: a mixed method study

OBJECTIVE

This study aimed to develop and apply a nomogram with good accuracy to predict the risk of CRAB infections in neuro-critically ill patients. In addition, the difficulties and expectations of application such a tool in clinical practice was investigated.

METHODS

A mixed methods sequential explanatory study design was utilized. We first conducted a retrospective study to identify the risk factors for the development of CRAB infections in neuro-critically ill patients; and further develop and validate a nomogram predictive model. Then, based on the developed predictive tool, medical staff in the neuro-ICU were received an in-depth interview to investigate their opinions and barriers in using the prediction tool during clinical practice. The model development and validation is carried out by R. The transcripts of the interviews were analyzed by Maxqda.

RESULTS

In our cohort, the occurrence of CRAB infections was 8.63% (47/544). Multivariate regression analysis showed that the length of neuro-ICU stay, male, diabetes, low red blood cell (RBC) count, high levels of procalcitonin (PCT), and number of antibiotics ≥ 2 were independent risk factors for CRAB infections in neuro-ICU patients. Our nomogram model demonstrated a good calibration and discrimination in both training and validation sets, with AUC values of 0.816 and 0.875. Additionally, the model demonstrated good clinical utility. The significant barriers identified in the interview include "skepticism about the accuracy of the model", "delay in early prediction by the indicator of length of neuro-ICU stay", and "lack of a proper protocol for clinical application".

CONCLUSIONS

We established and validated a nomogram incorporating six easily accessed indicators during clinical practice (the length of neuro-ICU stay, male, diabetes, RBC, PCT level, and the number of antibiotics used) to predict the risk of CRAB infections in neuro-ICU patients. Medical staff are generally interested in using the tool to predict the risk of CRAB, however delivering clinical prediction tools in routine clinical practice remains challenging.

Impact of antibiotic exposure on antibiotic-resistant Acinetobacter baumannii isolation in intensive care unit patients: a systematic review and meta-analysis

BACKGROUND

Acinetobacter baumannii (AB) poses a significant threat to critically ill patients in intensive care units (ICUs). Although an association between antibiotic exposure and resistant AB is reported in the literature, a synthesis of evidence in ICU patients is still lacking.

AIM

To summarize the evidence on the association between prior antibiotic exposure and the occurrence of resistant AB in ICU patients.

METHODS

Online databases were searched for cohort and case-control studies providing data on the association of interest. Carbapenem/multidrug-resistant AB isolation was compared with non-isolation; carbapenem/multidrug-resistant AB was compared with carbapenem/antibiotic-susceptible AB; and extensively drug-resistant AB isolation was compared with non-isolation. Each comparison was subjected to a restricted maximum likelihood random-effects meta-analysis per antibiotic class, estimating pooled ORs. Stratified meta-analyses were performed by study design, outcome type and association-measure adjustment.

FINDINGS

Overall, 25 high-quality studies were retrieved. Meta-analyses showed that carbapenem/multidrug-resistant AB isolation was associated with previous exposure to aminoglycosides, carbapenems, third-generation cephalosporines, glycylcyclines, and nitroimidazoles. Increased risk of isolation of carbapenem/multidrug-resistant AB isolation vs carbapenem/antibiotic-susceptible AB was shown for prior exposure to aminoglycosides, antipseudomonal penicillins, carbapenems, fluoroquinolones, glycopeptides, and penicillins. Third-generation cephalosporin exposure increased the risk of extensively drug-resistant AB isolation vs non-isolation.

CONCLUSION

This systematic review clarifies the role of antibiotic use in antibiotic-resistant AB spread in ICUs, although for some antibiotic classes the evidence is still uncertain due to the small number of adjusted analyses, methodological and reporting issues, and limited number of studies. Future studies need to be carried out with standardized methods and appropriate reporting of multivariable models.

Risk factors for progression to bacteremia among patients with nosocomial carbapenem-resistant Acinetobacter baumannii pneumonia in the Intensive Care Unit

Antibiotic-resistant Acinetobacter baumannii (A. baumannii) is a common cause of hospital-acquired infections. This study aimed to identify independent factors associated with progression from nosocomial pneumonia to bacteremia in patients infected with carbapenem-resistant A. baumannii (CR-AB). From 2019 to 2021, we conducted a retrospective anaylsis of the medical records of 159 nosocomial CR-AB pneumonia patients in our Intensive Care Unit (ICU). We employed both univariate and multivariable logistic regression models to identify factors associated with the progression of nosocomial CR-AB pneumonia to bacteremia. Among the 159 patients with nosocomial CR-AB pneumonia, 40 experienced progression to bacteremia and 38 died within 28 days following diagnosis. Patients who developed bacteremia had a significantly higher 28-day mortality rate compared to those without bloodstream infection (47.50% vs. 15.97%). Multivariable logistic regression revealed that higher levels of C-Reactive protein (CRP) (OR = 1.01) and the use of continuous veno-venous hemofiltration (CVVH) treatment (OR = 2.93) were independently associated with an elevated risk of developing bacteremia. Among patients who developed bloodstream infection, those who died within 28 days exhibited significantly higher level of interleukin-6 (IL-6), a greater frequency of antifungal drugs usage, and a longer duration of machanical ventilation compared to survivors. Furthermore, the use of antifungal drugs was the only factor that associated with 28-day mortality (OR = 4.70). In ICU patients with central venous catheters who have CR-AB pneumonia and are on mechanical ventilation, higher CRP levels and CVVH treatment are risk factors for developing bacteremia. Among patients with bacteremia, the use of antifungal drugs is associated with 28-day mortality.

Risk factors for acquiring Acinetobacter baumannii infection in the intensive care unit: experience from a Moroccan hospital

Introduction

Acinetobacter species are non-fermenting and ubiquitous Gram-negative coccobacilli, which in recent years have become the leading cause of healthcare-associated infections worldwide. Our objective here was to study the epidemiology and risk factors associated with Acinetobacter baumannii infections in the intensive care unit (ICU).

Methods

This retrospective case-control study was conducted collaboratively between the Medical Bacteriology Department and the two ICUs of the Military Hospital of Instruction Mohammed V-Rabat over a 3 month period.

Results

We included 180 patients, of whom 60 had A. baumannii infection. We observed a male predominance in both matched groups, with a sex ratio of 1.6. The median age was 67 years [interquartile range (IQR) 59.5-77]. The median length of stay in the ICU before infection was 8.5 days (IQR 5-14). Multivariate logistic regression analysis identified the risk factors statistically associated with A. baumannii infection at the ICU level as follows: duration of invasive procedures >7 days [odds ratio (OR)=1.02], parenteral nutrition (OR=3.514), mechanical ventilation (OR=3.024), imipenem (OR=18.72), colistin (OR=5.645), probabilistic antibiotic therapy >4 days (OR=9.063) and neoplastic pathology (OR=5.727).

Conclusion

Based on our results, it can be inferred that shortening the duration of stay in the resuscitation setting, implementing rational use of medical devices and optimizing antibiotic therapy could decrease the incidence of these infections.

Evaluation of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Molecular Typing of Acinetobacter baumannii in Comparison with Orthogonal Methods

Colonization and subsequent health care-associated infection (HCAI) with Acinetobacter baumannii are a concern for vulnerable patient groups within the hospital setting. Outbreaks involving multidrug-resistant strains are associated with increased patient morbidity and mortality and poorer overall outcomes. Reliable molecular typing methods can help to trace transmission routes and manage outbreaks. In addition to methods deployed by reference laboratories, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) may assist by making initial in-house judgments on strain relatedness. However, limited studies on method reproducibility exist for this application. We applied MALDI-TOF MS typing to A. baumannii isolates associated with a nosocomial outbreak and evaluated different methods for data analysis. In addition, we compared MALDI-TOF MS with whole-genome sequencing (WGS) and Fourier transform infrared spectroscopy (FTIR) as orthogonal methods to further explore their resolution for bacterial strain typing. A related subgroup of isolates consistently clustered separately from the main outbreak group by all investigated methods. This finding, combined with epidemiological data from the outbreak, indicates that these methods identified a separate transmission event unrelated to the main outbreak. However, the MALDI-TOF MS upstream approach introduced measurement variability impacting method reproducibility and limiting its reliability as a standalone typing method. Availability of in-house typing methods with well-characterized sources of measurement uncertainty could assist with rapid and dependable confirmation (or denial) of suspected transmission events. This work highlights some of the steps to be improved before such tools can be fully integrated into routine diagnostic service workflows for strain typing. IMPORTANCE Managing the transmission of antimicrobial resistance necessitates reliable methods for tracking outbreaks. We compared the performance of MALDI-TOF MS with orthogonal approaches for strain typing, including WGS and FTIR, for Acinetobacter baumannii isolates correlated with a health care-associated infection (HCAI) event. Combined with epidemiological data, all methods investigated identified a group of isolates that were temporally and spatially linked to the outbreak, yet potentially attributed to a separate transmission event. This may have implications for guiding infection control strategies during an outbreak. However, the technical reproducibility of MALDI-TOF MS needs to be improved for it to be employed as a standalone typing method, as different stages of the experimental workflow introduced bias influencing interpretation of biomarker peak data. Availability of in-house methods for strain typing of bacteria could improve infection control practices following increased reports of outbreaks of antimicrobial-resistant organisms during the COVID-19 pandemic, related to sessional usage of personal protective equipment (PPE).

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.

Reduction in the acquisition rate of carbapenem-resistant Acinetobacter baumannii (CRAB) after room privatization in an intensive care unit

BACKGROUND

Acinetobacter baumannii is one of the major pathogens responsible for healthcare-associated infections, especially in intensive care units (ICUs).

AIM

To evaluate the effect of room privatization in an ICU on the acquisition of carbapenem-resistant A. baumannii (CRAB).

METHODS

Between March and August 2017, a medical ICU was renovated from a multibed bay room to single rooms. Acquisition of CRAB was compared between patients admitted to the ICU over 18 months pre-renovation (September 2015 to February 2017) and post-renovation (September 2017 to February 2019). A Cox proportional hazard model was used with adjustment for demographics and comorbidities.

FINDINGS

Of the 901 patients, who contributed 8,276 patient-days, 95 (10.5%) acquired CRAB during their ICU stay. The CRAB acquisition rate was significantly higher during the pre-renovation period (1.87 per 100 patient-days) than during the post-renovation period (0.39 per 100 patient-days) (P < 0.001). In the multivariable Cox regression model, CRAB acquisition was significantly associated with the presence of a feeding tube (adjusted hazard ratio [aHR], 6.08; 95% confidence interval [CI], 2.46-15.06; P < 0.001), continuous renal replacement therapy (aHR, 1.66; 95% CI, 1.09-2.53; P = 0.019) and admission after renovation of the ICU to single rooms (aHR, 0.23; 95% CI, 0.12-0.41; P < 0.001).

CONCLUSIONS

Renovation of ICUs to single rooms is an efficient strategy to prevent transmission of multidrug-resistant organisms and hospital-acquired infections.

Beta-Lactamase Gene Expression Level of Hospital-Acquired CRAB Isolated from Children in Picu

Purpose

Acinetobacter baumannii is a major cause of hospital-acquired infections. Studies showed that carbapenem resistance was related to mortality. Carbapenem resistance depends on expression of β-lactamase in adults. The present study explores the relationship between β-lactamase gene expression and carbapenem resistance and outcomes in children with A. baumannii infections.

Patients and Methods

We gathered clinical data of 131 children diagnosed with hospital-associated A. baumannii infections from the pediatrics unit of Shengjing Hospital of China Medical University. We obtained 131 isolates of A. baumannii, determined the minimal inhibitory concentrations (MICs) for common antibiotics, and measured carbapenemase-encoding genes expression using real-time PCR.

Results

We isolated 131 strains, 89 of which were carbapenem-resistant (MIC ≥ 8 µg/mL), and 42 carbapenem-sensitive strains. Univariate analysis identified statistically significant differences between the carbapenem-resistant group and the carbapenem-sensitive group for in-hospital days before infection, previous deep vein catheterization, previous urinary catheterization, previous treatment with a carbapenem (meropenem/imipenem), and expression of oxa-51 and oxa-23. Logistic regression analysis of factors associated with carbapenem-resistant A. baumannii infections found significant associations with oxa-23 expression (hazard ratio [HR] 0.005, confidence interval [CI] 95% 0-0.153, P = 0.002) and previous carbapenem treatment (HR 0.031 CI 95% 0.1-0.959, P = 0.042). Of 131 patients, 27 died within 30 days. Cox regression analysis of factors associated with 30-day mortality from A. baumannii infections showed that cephalosporin combined with sulbactam (HR 0.271, CI 95% 0.101-0.723, P = 0.009) was associated with 30-day survival.

Conclusion

The expression of oxa-23 and the use of carbapenems were independent risk factors for carbapenem resistance. The use of cephalosporins combined with sulbactam was independently associated with 30-day survival. We recommend using cephalosporins combined with sulbactam in children infected with A. baumannii.

[A systematic review and expert's analysis of risk factors of infections in adults due to carbapenem-resistant Pseudomonas aeruginosa or Acinetobacter baumannii in Spain]

OBJECTIVE

The aim of the study is to identify risk factors associated to infections caused by carbapenem-resistant Pseudomonas aeruginosa (CRPA) and carbapenem-resistant Acinetobacter baumannii (CRAB) in adult patients through a systematic literature review, classify them according to their importance and provide recommendations by experts in the Spanish context.

METHODS

We developed a systematic literature review to identify risk factors associated to CRPA or CRAB infections and they were evaluated and discussed by a multidisciplinary panel of experts.

RESULTS

There were included 29 studies for P. aeruginosa and 23 for A. baumannii out of 593 identified through systematic literature review. We identified 38 risk factors for P. aeruginosa and 36 for A. baumannii. After risk factor evaluation by the panel of experts, results for CRPA were: 11 important, 10 slightly important and 15 unimportant risk factors; and for CRAB were: 9 important, 5 slightly important and 19 unimportant risk factors. For both pathogens, previous use of antibiotics and hospitalization were important risk factors.

CONCLUSIONS

We could identify the main risk factors associated to CRPA and CRAB through literature review. There is a need for developing additional studies with higher levels of evidence to identify sooner and better infected patients through associated risk factors.

Microbiology of Ventilator-associated Pneumonia in a Tertiary Care Cancer Hospital

Background

Ventilator-associated pneumonia (VAP) is an important cause of healthcare-associated infections, resulting in prolonged hospitalization with increased morbidity and mortality. Knowledge of predominant local pathogens and their antimicrobial susceptibility patterns helps in selection of appropriate initial antibiotic therapy in these critical cases.

Aim and objective

The aim and objective of this study is to characterize the microbiology and antimicrobial susceptibility patterns of VAP isolates in a tertiary cancer center.

Materials and methods

This is a 4-year qualitative observational study carried out at a tertiary care cancer hospital in Mumbai. All nondirect bronchoalveolar lavage specimens from patients with a clinical suspicion of VAP sent from the critical care unit to the department of microbiology were processed as per standard laboratory procedures. All isolates were identified to species level and an antimicrobial susceptibility testing was performed by the Kirby–Bauer disk diffusion method and/or the VITEK 2 automated identification and susceptibility system, according to Clinical and Laboratory Standards Institute guidelines.

Results

The study comprised 1,074 patients: 710 (66.10%) men and 364 (33.90%) women. A total of 827 bacterial isolates were obtained with 780 (94.32%) gram-negative organisms and 47 (5.68%) gram-positive organisms; of which Acinetobacter baumannii (38.7%), Pseudomonas aeruginosa (17.5%), and Klebsiella pneumoniae (16.6%) were the commonest. Of gram-negative bacilli, multidrug-resistant organisms constituted 87.50% and were susceptible to colistin.

Conclusions

VAP is associated with pathogens, such as A. baumannii, P. aeruginosa, and K. pneumoniae in our setting. High rates of resistance to aminoglycosides, β-lactam-β-lactamase inhibitor combinations, and carbapenems were noted.

How to cite this article

Sangale A, Bhat V, Kelkar R, Biswas S. Microbiology of Ventilator-associated Pneumonia in a Tertiary Care Cancer Hospital. Indian J Crit Care Med 2021;25(4):421–428.

Usos y limitaciones de la lámpara ultravioleta germicida portátil para la desinfección de superficies

RESUMENLa morbimortalidad causada por infecciones vinculadas a la atención sanatoria ha llevado a cuestionar si los métodos de desinfección convencionales son inadecuados y se requieren métodos complementarios, como la fumigación de la habitación y la irradiación ultravioleta. Ello ha dado lugar a la preocupación por que estos métodos alternativos puedan poner en riesgo al personal sanitario y a los pacientes.Objetivos. (1) Determinar la eficacia de la lámpara ultravioleta C germicida portátil para la desinfección de superficies, (2) evaluar el cambio de la humedad relativa (HR) y las distintas distancias específicas en las tasas de letalidad bacteriana, y (3) evaluar los posibles problemas a que conlleva la exposición.Métodos. En el presente estudio se investiga si una lámpara germicida portátil puede desinfectar de forma eficaz superficies tratadas con esporulación o germinación bacteriana y se evalúa el efecto de condiciones ambientales cambiantes, como la humedad relativa (HR), la posición y las distancias específicas, en las tasas de letalidad germicida.Resultados. Se constató una mejor tasa de letalidad con una HR de 40-65% y en un rango de temperatura de 21-24°C. Tanto la HR alta como la HR baja interfirieron con la capacidad de la radiación UV-C para inactivar la germinación microbiana. En el caso de la esporulación bacteriana, el aumento del secado de la superficie fue el factor de mayor importancia para aumentar la tasa de letalidad.Conclusiones. En esta investigación se demostró la eficacia de la radiación UV-C bajo condiciones óptimas, irradiación directa y una distancia específica corta (12.7 cm). Sin embargo, cuando es utilizada en condiciones que no son óptimas existen limitaciones. El aumento de la distancia y los ángulos de irradiación indirecta resultaron en tasas de letalidad más bajas. Cabe señalar que durante su uso es importante minimizar la exposición innecesaria de pacientes y personal sanitario.

Acinetobacter: An Enemy after Head and Neck Cancer Operations with Microvascular Free Flap Reconstruction?

Background: Patients after head and neck cancer reconstructive surgical procedures are predisposed to have post-operative surgical site infections (SSI) develop. They are very often caused by multi-drug resistant strains, including Acinetobacter baumannii as the most common one. Methods: The aim of the study was to determine important risk factors contributing to SSI of A. baumannii origin. The analysis included 134 head and neck cancer patients after salvage operations with microvascular free flap reconstruction. The A. baumannii was cultured in 27 of all 48 infected patients. Results: The following risk factors were significantly associated with A. baumannii infection: re-hospitalization before reconstructive operation (p = 0.00011), massive blood loss (p = 0.00277), and need of revision surgical procedure (p = 0.00419). Of patients with A. baumannii infection, 48% were hospitalized in a general intensive care unit (ICU) after operation that, together with prolonged intubation, constituted a strong risk factor of that infection (p = 0.01077). Mean time of hospital stay was significantly longer in the A. baumannii group (58 days vs. 35 days; p = 0.02697). Conclusions: Our analysis identified a subset of head and neck cancer patients after salvage operation with microvascular free flap reconstruction who are at high risk of A. baumannii infection developing. Previously hospitalized patients with extensive blood loss and need of surgical revision necessitate increased monitoring for the development of this complication. Mechanical ventilation and hospital stay in an ICU should be shortened maximally or avoided in that challenging group of patients. Early recognition of patients at high risk remains a key point to prevent or limit the spread of A. baumannii 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.

Antimicrobial resistance patterns and their encoding genes among clinical isolates of Acinetobacter baumannii in Ahvaz, Southwest Iran

Acinetobacter baumannii is one of the most important organisms in nosocomial infections. Antibiotic resistance in this bacterium causes many problems in treating patients. This study aimed to investigate antibiotic resistance patterns and resistance-related, genes in clinical isolates of Acinetobacter baumannii. This descriptive study was conducted on 124 isolates of Acinetobacter baumannii collected from clinical samples in two teaching hospitals in Ahvaz. The antibiotic resistance pattern was determined by disk diffusion. The presence of genes coding for antibiotic resistance was determined using the polymerase chain reaction method. Out of 124 isolates, the highest rate of resistance was observed for rifampin (96.8%). The resistance rate for imipenem, meropenem, colistin, and polymyxin-B were 78.2%, 73.4%, 0.8% and 0.8%, respectively. The distribution of qnrA, qnrB, qnrS, Tet A, TetB, and Sul1genes were 52.6%, 0%, 3.2%, 93.5% 69.2%, and 6.42%, respectively. High prevalence of tetA, tetB, and qnrA genes among Acinetobacter baumannii isolated strains in this study indicate the important role of these genes in multidrug resistance in this bacteria. • Acinetobacter baumannii is an important human pathogen that has attracted the attention of many researchers Antibiotic resistance in this bacterium causes many problems in treating patients. • The resistance rate for imipenem, meropenem, colistin, and polymyxin-B were 78.2%, 73.4%, 0.8% and 0.8%, respectively. The distribution of qnrA, qnrB, qnrS, Tet A, TetB, and Sul1genes were 52.6%, 0%, 3.2%, 93.5% 69.2%, and 6.42%, respectively.

Temporal association between carbapenems usage and antimicrobial resistance in gram-negative bacteria at a tertiary hospital in Nanjing, China

In this study, we investigated the temporal association between carbapenems usage and antimicrobial resistance among major Gram-negative bacteria, using the data of quarterly carbapenems consumptions and percentages of antibiotic resistance for Gram-negative bacteria from inpatients from 2013 to 2017 in a tertiary hospital from Jiangsu Province, China. First, carbapenems consumption showed an increasing trend in the past 5 years, accompanied with the rising rates of A. baumannii and P. aeruginosa resistance against imipenem. In A. baumannii, we identified correlations between carbapenems consumption and antimicrobial resistance against piperacillin/tazobactam, ceftazidime, ciprofloxacin and imipenem, respectively. Additionally, close correlations were observed between carbapenems consumption and antimicrobial resistance against ceftazidime and ciprofloxacin in E. coli. Our data indicated that a significant positive correlation between the usage of carbapenems and the rate of antimicrobial resistance among A. baumannii and E. coli, respectively. Carbapenems should be cautiously prescribed to prevent antimicrobial resistance outbreak in A. baumannii and E. coli.

Insights into Acinetobacter baumannii: A Review of Microbiological, Virulence, and Resistance Traits in a Threatening Nosocomial Pathogen

Being a multidrug-resistant and an invasive pathogen, Acinetobacter baumannii is one of the major causes of nosocomial infections in the current healthcare system. It has been recognized as an agent of pneumonia, septicemia, meningitis, urinary tract and wound infections, and is associated with high mortality. Pathogenesis in A. baumannii infections is an outcome of multiple virulence factors, including porins, capsules, and cell wall lipopolysaccharide, enzymes, biofilm production, motility, and iron-acquisition systems, among others. Such virulence factors help the organism to resist stressful environmental conditions and enable development of severe infections. Parallel to increased prevalence of infections caused by A. baumannii, challenging and diverse resistance mechanisms in this pathogen are well recognized, with major classes of antibiotics becoming minimally effective. Through a wide array of antibiotic-hydrolyzing enzymes, efflux pump changes, impermeability, and antibiotic target mutations, A. baumannii models a unique ability to maintain a multidrug-resistant phenotype, further complicating treatment. Understanding mechanisms behind diseases, virulence, and resistance acquisition are central to infectious disease knowledge about A. baumannii. The aims of this review are to highlight infections and disease-producing factors in A. baumannii and to touch base on mechanisms of resistance to various antibiotic classes.

Risk factors for the first episode of Acinetobacter baumannii resistant to colistin infection and outcome in critically ill patients

Introduction

To identify risk factors for the first episode of Acinetobacter baumannii resistant to colistin (ABCR) infection in critically ill patients.

Aim

Prospective observational study.

Methodology

ICU patients who required mechanical ventilation for >48 h during a 36 month period. Clinical and microbiological data were studied; characteristics of patients infected with ABCR were compared with those of critically ill patients who presented infection due to A. baumannii sensitive to colistin (ABCS).

Results

Twenty patients presented with ABCR infection, and 57 patients ABCS infection. Compared to patients with ABCS infection, patients suffering from ABCR infection had received more frequent and/or for longer duration dosing of several antibiotics active against Gram-negative bacteria (P<.05). Moreover, the duration of mechanical ventilation, and the presence of invasive procedures and tracheostomy prior to infection were associated with ABCR infections. The duration of carbapenem administration was an independent risk factor for ABCR infection [odds ratio (OR), 1.21; 95 % confidence interval (95 %, CI), 1.00 to 1.45; P=.049]. Mortality rate for patients with ABCR infection was higher (85 vs 39 % for the ABCS group). Sequential organ failure assessment score on admission, Charlson score and ABCR infection were independent risk factors for mortality.

Conclusion

ABCR infection is a life-threatening infection, which might be more common in patients with previous use of antibiotics, especially carbapenems.

Bystander Selection for Antimicrobial Resistance: Implications for Patient Health

Antimicrobial therapy promotes resistance emergence in target infections and in off-target microbiota. Off-target resistance emergence threatens patient health when off-target populations are a source of future infections, as they are for many important drug-resistant pathogens. However, the health risks of antimicrobial exposure in off-target populations remain largely unquantified, making rational antibiotic stewardship challenging. Here, we discuss the contribution of bystander antimicrobial exposure to the resistance crisis, the implications for antimicrobial stewardship, and some novel opportunities to limit resistance evolution while treating target pathogens.

Incidence, risk factors and outcome of multi-drug resistant Acinetobacter baumannii nosocomial infections during an outbreak in a burn unit

BACKGROUND

Multidrug-Resistant Acinetobacter baumannii (MR-AB) can cause outbreaks in burn units. We aimed to study the incidence, risk factors and outcome of MR-AB infections in a burn unit (BU).

METHODS

A prospective study was conducted from April to November, 2014 during an outbreak in a BU in Paris. Weekly surveillance cultures were performed to determine MR-AB colonization. MR-AB nosocomial infections, discharge or death without MR-AB infection were considered as competing events. To identify risk factors for MR-AB infection, baseline characteristics and time-dependent variables were investigated in univariate analyses using Cox models.

RESULTS

Eighty-six patients admissions were analyzed during the study period. Among them, 15 (17%) acquired MR-AB nosocomial infection. Median time to infection was 22days (interquartile range: 10-26 days). Cumulative incidence of MR-AB infections was 15% at 28days (95% CI=8-24). Risk factors for MR-AB infection in univariate analysis were SAPS II (Hazard Ratio (HR):1.08; 95% CI:1.05-1.12; P<0.0001) and ABSI (Abbreviated Burn Severity Index) scores (HR:1.32; 95% CI:1.12-1.56; P=0.001), MR-AB colonization (HR:10.2; 95%CI:2.05-50.3; P=0.004), invasive procedures (ventilation, arterial and/or venous catheter) (P=0.0001) and ≥2 skin grafts (HR:10.2; 95% CI:1.76-59.6; P=0.010). MR-AB infection was associated with an increased risk of death (HR: 7.11; 95%CI: 1.52-33.2; P=0.013) and longer hospital stay with a median estimated increase of 10days (IQR: 6; 14).

CONCLUSIONS

Incidence of MR-AB nosocomial infection was high during this outbreak, and was associated with prolonged hospitalization and increased risk of death. High patient severity scores, prior MR-AB colonization, invasive procedures and repeated skin grafts were associated with an increased risk of nosocomial infection.

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.

Identifying Risk Factors for Healthcare-Associated Infections Caused by Carbapenem-Resistant Acinetobacter baumannii in a Neonatal Intensive Care Unit

Objectives

Acinetobacter baumannii is a causative pathogen of various healthcare-associated infections (HAIs) and is particularly prevalent in high-risk hospital settings. This study aimed to determine risk factors associated with HAIs caused by carbapenem-resistant A. baumannii (CRAB) in a neonatal intensive care unit (NICU).

Methods

This prospective study was performed between January 2013 and June 2014 among NICU patients at the Mansoura University Children's Hospital, Mansoura, Egypt. Neonates who developed HAIs due to CRAB were assigned to a case group, while those infected with carbapenem-sensitive A. baumannii (CSAB) were assigned to a control group.

Results

Among the 124 neonates who developed A. baumannii-caused HAIs during the study period, 91 (73.4%) were caused by CRAB and 33 (26.6%) were caused by CSAB. Prematurity, premature rupture of the membranes (PROM), a previous stay in another hospital, prolonged NICU stay, the presence of invasive devices, previous exposure to carbapenems or aminoglycosides and prolonged antibiotic therapy before infection were significantly associated with CRAB-caused HAIs. A multivariate logistic regression analysis identified prematurity (adjusted odds ratio [aOR] = 25.3; P <0.01), mechanical ventilation (aOR = 18.9; P <0.01) and the previous use of carbapenems (aOR = 124.7; P <0.01) or aminoglycosides (aOR = 22.6; P = 0.04) to be independent risk factors for CRAB infections.

Conclusion

Various risk factors were significantly associated with CRAB-caused HAIs among the studied NICU patients.

Clinical and economic impact of antibiotic resistance in developing countries: A systematic review and meta-analysis

INTRODUCTION

Despite evidence of the high prevalence of antibiotic resistant infections in developing countries, studies on the clinical and economic impact of antibiotic resistance (ABR) to inform interventions to contain its emergence and spread are limited. The aim of this study was to analyze the published literature on the clinical and economic implications of ABR in developing countries.

METHODS

A systematic search was carried out in Medline via PubMed and Web of Sciences and included studies published from January 01, 2000 to December 09, 2016. All papers were considered and a quality assessment was performed using the Newcastle-Ottawa quality assessment scale (NOS).

RESULTS

Of 27 033 papers identified, 40 studies met the strict inclusion and exclusion criteria and were finally included in the qualitative and quantitative analysis. Mortality was associated with resistant bacteria, and statistical significance was evident with an odds ratio (OR) 2.828 (95%CI, 2.231-3.584; p = 0.000). ESKAPE pathogens was associated with the highest risk of mortality and with high statistical significance (OR 3.217; 95%CIs; 2.395-4.321; p = 0.001). Eight studies showed that ABR, and especially antibiotic-resistant ESKAPE bacteria significantly increased health care costs.

CONCLUSION

ABR is associated with a high mortality risk and increased economic costs with ESKAPE pathogens implicated as the main cause of increased mortality. Patients with non-communicable disease co-morbidities were identified as high-risk populations.

The uses and limitations of a hand-held germicidal ultraviolet wand for surface disinfection

The morbidity and mortality from healthcare associated infections has raised concern that conventional disinfection methods are inadequate and that other adjunct methods such as room fumigation and ultraviolet irradiation may be needed. There is also concern that these alternative methods may pose a risk to workers and patients.

OBJECTIVES

(1) Determine the efficacy of a germicidal UV-C wand for surface disinfection, (2) evaluate changing relative humidity (RH) and different target distances on bacteria kill rates, and (3) assess potential exposure concerns.

METHODS

This study investigates whether a hand-held germicidal wand can efficaciously disinfect surfaces treated with either a vegetative or spore forming bacterium and to evaluate the effect of changing environmental conditions such as relative humidity (RH), target position, and target distances on microbial kill rates.

RESULTS

Kill rate was best at 40-65% RH at a temperature range of 21-24°C. Both high and low RH interfered with the ability of UV-C to kill the vegetative microbe. In the case of the spore forming bacterium, increased surface drying time was the most significant factor increasing kill rate.

CONCLUSIONS

This research demonstrates that UV-C was efficacious under optimal conditions, a direct beam exposure, and a short target distance (12.7 cm). However, there are limitations when used in non-optimal conditions. Increased distance and indirect beam angles resulted in lower kill rates. It is also important to minimize unnecessary patient and worker exposure during its use.

The effect of immune modulation of Streptococcus constellatus SC10 strain upon Acinetobactor baumannii infection

Acinetobacter baumannii is a tiny, plump and rod-shaped Gram-negative coccobacillus, notorious as an opportunistic pathogen, which is now being considered by CDC as a serious public health threat. Preventing colonization may be a better therapeutic choice using microbiota to protect against A. baumannii transmission. Human microbiota not only regulates immune homeostasis as well provides essential health benefits therefore discovering the interface due microbiota in host immune system will allow to recognise novel immuno- or microbe-based therapies. Streptococcus constellatus frequently isolated from oral cavity was selected for this study to check if its guards against A. baumannii by improving the immune response and the immune signalling pathway. In a mouse model we explored various parameters which include mouse body weight, internal organ weight, level of sIgA and different cytokine changes to evaluate its prophylactic effect against A. baumannii. Administration of S. constellatus SC10 was able to control the weight lose induced by A. bumannii infection in both the protected and treated groups. Particularly resistant against infection was more in treated group where the different cytokine following administration of SC10 strain remarkably controlled the infection and induced more sIgA production. The level of different interleukins IL-4, IL-10, IL-12 and IFN-γ was suppressed in treatment and protected group after exposure of S. constellatus. The excretion of sIgA following infection was many folds high in both group treated and protected groups Study suggests that SC10 L16 have potential immunomodulating effect which is able to regulate cytokines and sIgA response at the early phase of infection and modulate the further progress of clinical symptoms during infection.

Emergence of Carbapenem Resistant Non-Fermenting Gram-Negative Bacilli Isolated in an ICU of a Tertiary Care Hospital

INTRODUCTION

The emergence and spread of Multi-Drug Resistant (MDR) Non-Fermenting Gram-Negative Bacilli (NFGNB) in Intensive Care Units (ICU) and their genetic potential to transmit diverse antibiotic resistance regardless of their ability to ferment glucose poses a major threat in hospitals. The complex interplay of clonal spread, persistence, transmission of resistance elements and cell-cell interaction leads to the difficulty in controlling infections caused by these multi drug-resistant strains. Among non-fermenting Gram-negative rods, the most clinically significant species Pseudomonas aeruginosa, Acinetobacter baumannii and Stenotrophomonas maltophilia are increasingly acquiring resistant to carbapenems. Carbapenems once considered as a backbone of treatment of life threatening infections appears to be broken as the resistance to carbapenems is on rise.

AIM

To document the prevalence of carbapenem resistance in non-fermenting Gram-negative bacilli isolated from patients with respiratory tract infections in the ICU of Himalayan Institute of Medical Sciences, Dehradun.

MATERIALS AND METHODS

This is a cross-sectional study conducted in ICU patients between October 2015 to March 2016. A total of 366 lower respiratory tract samples were collected from 356 patients with clinical evidence of lower respiratory tract infections in form of Endotracheal (ET) aspirate, Tracheal Tube (TT) aspirate and Bronchoalveolar Lavage (BAL) specimen. Organism identification and the susceptibility testing was done by using an automated system VITEK 2.

RESULTS

Out of 366 samples received 99 NFGNB were isolated and most common sample was ET aspirate sample 256 (64.5%). Acinetobacter baumannii was the most common NFGNB isolated 63 (63.63%) followed by Pseudomonas aeruginosa 25 (25.25%), Elizabethkingia meningoseptica seven (7.07%) and Strenotrophomonas maltophilia four (4.04%). We observed that 90.5% Acinetobacter baumannii were resistant to imipenem and 95.2% resistant to meropenem, Pseudomonas aeruginosa came out to be 52% resistant to imipenem and 56% resistant to meropenem while Stenotrophomonas maltophilia and Elizabethkingia meningoseptica were 100% resistant to carbapenems as they are intrinsically resistant to carbapenems.

CONCLUSION

The resistance rate of carbapenems for NFGNB infections is very high in our study and variable in different regions. Overall carbapenem resistance is on rise. So, the infection control team and microbiologist needs to work together to determine the risk carried by multi drug resistant non-fermenting gram-negative infections and the resistance surveillance programs are mandatory to control these bacteria in ICU settings.

Clinical Features and Risk Factors for Development of Breakthrough Gram-Negative Bacteremia during Carbapenem Therapy

With the increasing use of carbapenems, carbapenem-resistant Gram-negative bacteria have become a major concern in health care-associated infections. The present study was performed to evaluate the clinical and microbiological features of breakthrough Gram-negative bacteremia (GNB) during carbapenem therapy and to assess risk factors for development of breakthrough GNB. A case-control study was performed at a tertiary hospital from 2005 to 2014. Case patients were defined as individuals whose blood cultures grew Gram-negative bacteria while the patients were receiving carbapenems for at least 48 h before breakthrough GNB. Age-, sex-, and date-matched controls were selected from patients who received carbapenem for at least 48 h and did not develop breakthrough GNB during carbapenem treatment. A total of 101 cases of breakthrough GNB were identified and compared to 100 controls. The causative microorganisms for breakthrough GNB were Stenotrophomonas maltophilia (n = 33), Acinetobacter baumannii (n = 32), Pseudomonas aeruginosa (n = 21), and others (n = 15). Approximately 90% of S. maltophilia isolates were susceptible to levofloxacin and trimethoprim-sulfamethoxazole. The most common infection types were primary bacteremia (38.6%) and respiratory infections (35.6%). More than half of the patients died within a week after bacteremia, and the 30-day mortality rate was 70.3%. In a multivariate analysis, a longer hospital stay, hematologic malignancy, persistent neutropenia, immunosuppressant use, and previous colonization by causative microorganisms were significantly associated with breakthrough GNB. Our data suggest that S. maltophilia, A. baumannii, and P. aeruginosa are the major pathogens of breakthrough GNB during carbapenem therapy, in association with a longer hospital stay, hematologic malignancy, persistent neutropenia, immunosuppressant use, and previous colonization.

Multidrug Resistance of Acinetobacter Baumannii in Ladoke Akintola University Teaching Hospital, Osogbo, Nigeria

Acinetobacter baumannii is a ubiquitous pathogen that has emerged as a major cause of healthcare-associated infections at Ladoke Akintola University Teaching Hospital. Isolates were assayed according to standard protocol. The isolates were subjected to molecular techniques to detect blaOXA, blaTEM, blaCTX-M, and blaSHV genes in strains of the A. baumannii isolates.

The prevalence of A. baumannii was 8.5% and was most prevalent among patients in the age group 51–60 (36%); the male patients (63.6%) were more infected than their female counterparts. Patients (72.7%) in the intensive care unit (ICU) were most infected with this organism. The isolates showed 100% resistance to both amikacin and ciprofloxacin and 90.9% to both ceftriaxone and ceftazidime, while resistance to the other antibiotics used in this study were: piperacillin (81.8%), imipenem (72.7%), gentamycin (72.2%), and meropenem (63.6%). None of the isolates was, however, resistant to colistin. PCR results showed that blaOXA, blaTEM, and blaCTX-M genes were positive in some isolates, while blaSHV was not detected in any of the isolates.

This study has revealed that the strains of A. baumannii isolated are multiple drug resistant. Regular monitoring, judicious prescription, and early detection of resistance to these antibiotics are, therefore, necessary to check further dissemination of the organism.

Central Nervous System Depressants Poisoning and Ventilator Associated Pneumonia: An Underrated Risk Factor at the Toxicological Intensive Care Unit

BACKGROUND

Ventilator-Associated Pneumonia (VAP) is the main cause of nosocomial infection at intensive care units (ICUs), which causes high mortality and morbidity.

OBJECTIVES

The objective of the present survey was to identify the VAP risk and prognostic factors among poisoned patients, who were admitted to the toxicological ICU (TICU), especially central nervous system (CNS) depressants due to their prevalence and importance.

PATIENTS AND METHODS

A case-control study was conducted at the Loghman Hakim hospital between March 2013 and March 2014. Among 300 poisoned patients with mechanical ventilator ≥ 48 hours, 150 patients, who had developed microbiologically-confirmed VAP were considered as the VAP group and 150 without VAP were defined as the control group. The following data were collected; age, gender, type of poisoning, glasgow coma score, Acute physiology and chronic health evaluation (APACHE) II score, length of hospital stay, previous antibiotic use, microbial culture of the trachea, body temperature, leukocyte count, and patients' outcome. Based on the type of poisoning, patients were divided into three groups including: opioid, CNS depressants and others. All data were expressed as means (SD) for continuous variables and frequencies for categorical variables. Logistic regression was used to determine the relationship between risk factors and VAP.

RESULTS

The mean age of the patients was 33.9 ± 14.3 years. The probable VAP incidence and mortality were 22% and 18.6%, respectively. The rate of CNS depressant versus opioid use (odds ratio, 3.74; P < 0.027), APACHE II (odds ratio, 1.28; P < 0.000) and length of hospital stay (odds ratio, 2.15; P < 0.000) were the independent risk factors for VAP. While, the APACHE II score (odds ratio, 1.12; P < 0.044) and length of hospital stay (odds ratio, 2.15; P < 0.000) were the independent predictors of VAP mortality among these patients. The most common microorganisms in VAP cases were Methicillin-Resistant Staphylococcus aureus (MRSA) and Acinetobacter sp. (56.7% and 12.7%, respectively).

CONCLUSIONS

Central nervous system depressant was an important risk factor for VAP among poisoned patients. Hypoventilation due to CNS depression can lead to VAP. The APACHE II and length of hospital stay were shown as independent predictors of VAP and mortality among these patients.

Nosocomial Infections Caused by Acinetobacter baumannii: Are We Losing the Battle?

BACKGROUND

The incidence of nosocomial infections caused by multi-drug- and extended-drug resistant strains of Acinetobacter is constantly increasing all over the world, with a high mortality rate. We analyzed the in-hospital data on the sensitivity of Acinetobacter baumannii isolates and correlated them with antibiotic treatment and clinical outcomes of nosocomial infections over a 17-mo period.

METHODS

Retrospective analysis was performed at the Clinical Center "Bezanijska kosa," Belgrade, Serbia. Microbiologic data (number and sensitivity of A. baumannii isolates) and clinical data (medical records of 41 randomly selected patients who developed nosocomial infection caused by A. baumannii) were matched.

RESULTS

Acinetobacter baumannii, detected in 279 isolates and obtained from 19 patients (12% of all samples), was resistant to almost all antibiotics tested, including carbapenems, with the exception of colistin and tigecycline. It was obtained most often from the respiratory tract samples. Empiric treatment of the nosocomial infections (pneumonia in 75% of cases) involved cephalosporins, metronidazole, and carbapenems (80%, 66%, and 61% of patients, respectively), whereas tigecyclin and colistin were used primarily in targeted therapy (20% and 12% of patients, respectively). The mortality rate of patients treated empirically was significantly higher (p < 0.01), reaching 100% in the elderly.

CONCLUSIONS

Nosocomial A. baumannii infections represent a significant clinical problem because of their high incidence, lack of susceptibility to the most commonly used antibiotics, and the often inappropriate treatment, which favors the development of multi-drug-resistant strains.

Incidence of Multidrug-Resistant Pseudomonas Spp. in ICU Patients with Special Reference to ESBL, AMPC, MBL and Biofilm Production

BACKGROUND

Multidrug-resistant (MDR) Pseudomonas spp. have been reported to be the important cause of ICU infections. The appearance of ESBL, AmpC and MBL genes and their spread among bacterial pathogens is a matter of great concern. Biofilm production also attributes to antimicrobial resistance due to close cell to cell contact that permits bacteria to more effectively transfer plasmids to one another. This study aimed at determining the incidence of ESBL, AmpC, MBL and biofilm producing Pseudomonas spp. in ICU patients.

MATERIAL AND METHODS

The clinical specimens were collected aseptically from 150 ICU patients from February 2012 to October 2013. Identification and antimicrobial susceptibility was performed according to Clinical and Laboratory Standards Institute (CLSI) guidelines. ESBLs and AmpC were detected phenotypically and genotypically. MBL was detected by modified Hodge and imipenem-EDTA double-disk synergy test.

RESULTS

Pseudomonas spp. 35(28%) were the most prevalent pathogen in ICU infections. Multidrug resistance and biofilm production was observed in 80.1% and 60.4% isolates, respectively. Prevalence of ESBL, AmpC and MBL was 22.9%, 42.8% and 14.4%, respectively. The average hospital stay was 25 days and was associated with 20% mortality.

CONCLUSIONS

A regular surveillance is required to detect ESBL, AmpC and MBL producers especially in ICU patients. Carbapenems should be judiciously used to prevent their spread. The effective antibiotics, such as fluoroquinolones and piperacillin-tazobactum should be used after sensitivity testing.

Comparative Phosphoproteomics Reveals the Role of AmpC β-lactamase Phosphorylation in the Clinical Imipenem-resistant Strain Acinetobacter baumannii SK17

Nosocomial infectious outbreaks caused by multidrug-resistant Acinetobacter baumannii have emerged as a serious threat to human health. Phosphoproteomics of pathogenic bacteria has been used to identify the mechanisms of bacterial virulence and antimicrobial resistance. In this study, we used a shotgun strategy combined with high-accuracy mass spectrometry to analyze the phosphoproteomics of the imipenem-susceptible strain SK17-S and -resistant strain SK17-R. We identified 410 phosphosites on 248 unique phosphoproteins in SK17-S and 285 phosphosites on 211 unique phosphoproteins in SK17-R. The distributions of the Ser/Thr/Tyr/Asp/His phosphosites in SK17-S and SK17-R were 47.0%/27.6%/12.4%/8.0%/4.9% versus 41.4%/29.5%/17.5%/6.7%/4.9%, respectively. The Ser-90 phosphosite, located on the catalytic motif S(88)VS(90)K of the AmpC β-lactamase, was first identified in SK17-S. Based on site-directed mutagenesis, the nonphosphorylatable mutant S90A was found to be more resistant to imipenem, whereas the phosphorylation-simulated mutant S90D was sensitive to imipenem. Additionally, the S90A mutant protein exhibited higher β-lactamase activity and conferred greater bacterial protection against imipenem in SK17-S compared with the wild-type. In sum, our results revealed that in A. baumannii, Ser-90 phosphorylation of AmpC negatively regulates both β-lactamase activity and the ability to counteract the antibiotic effects of imipenem. These findings highlight the impact of phosphorylation-mediated regulation in antibiotic-resistant bacteria on future drug design and new therapies.

Modeling the impact of interventions against Acinetobacter baumannii transmission in intensive care units

The efficacy of infection control interventions against Acinetobacter baumannii remains unclear, despite such information being critical for effective prevention of the transmission of this pathogen. Mathematical modeling offers an alternative to clinical trials, which may be prohibitively expensive, unfeasible or unethical, in predicting the impact of interventions. Furthermore, it allows the ability to ask key “what if” questions to evaluate which interventions have the most impact. We constructed a transmission dynamic model to quantify the effects of interventions on reducing A. baumannii prevalence and the basic reproduction ratio (R₀) in intensive care units (ICUs). We distinguished between colonization and infection, and incorporated antibiotic exposure and transmission from free-living bacteria in the environment. Under the assumptions and parameterization in our model, 25% and 18% of patients are colonized and infected with A. baumannii, respectively; and R₀ is 1.4. Improved compliance with hand hygiene (≥87%), enhanced environmental cleaning, reduced length of ICU stay of colonized patients (≤ 10 days), shorter durations of antibiotic treatment of A. baumannii (≤6 days), and isolation of infected patients combined with cleaning of isolation rooms are effective, reducing R₀ to below unity. In contrast, expediting the recovery of the intestinal microbiota (e.g. use of probiotics) is not effective. This study represents a biologically realistic model of the transmission dynamics of A. baumannii, and the most comprehensive analysis of the effectiveness of interventions against this pathogen. Our study provides important data for designing effective infection control interventions.

Clinical importance and cost of bacteremia caused by nosocomial multi drug resistant acinetobacter baumannii

BACKGROUND

A. baumannii is an important nosocomial pathogen associated with high mortality, morbidity and medical cost.

AIM

The aim of this study was to investigate risk factors for MDR A. baumannii bacteremia and also evaluate cost of hospitalization of these patients.

METHODS

Study was conducted in Ankara Atatürk Training and Research Hospital. Patients who were hospitalized in ICU and diagnosed for nosocomial blood stream infection (BSI) between January 2007 and December 2010 were checked retrospectively. Patients with nosocomial BSI caused by multidrug resistant A. baumannii were compared with the patients who had BSI caused by other Gram-negative microorganisms in terms of risk factors, mortality and medical costs.

FINDINGS

In multivariate analysis previous use of carbapenem, quinolone and metronidazole, and SAPS II score were found as independent risk factors. In case group; immunosupression, SAPS II score, and hospital stay until infection were independently associated with mortality in multivariate analysis.

CONCLUSION

Our results suggest that the occurrence of MDR A.baumannii bacteremia was related with the usage of the wide spectrum antibiotics, and mortality rates were increased in patients that high SAPS II scores, long term hospitalization. Infection control procedures and limited antibiotic usage are very important for prevent nosocomial infections.

Acinetobacter baumannii infections in a South African paediatric intensive care unit

OBJECTIVES

To describe and compare characteristics and outcomes of patients colonized or infected with Acinetobacter baumannii (cases) to a control group.

METHODS

A retrospective case-controlled study of patients admitted to a South African paediatric intensive care unit (PICU) between January and December 2010.

RESULTS

Acinetobacter baumannii was isolated in 194 patients. Mortality was similar between cases (9.3%) and controls (9.8%). Median duration of PICU stay and mechanical ventilation in cases vs. controls was 10 vs. 2 (p < 0.0001) and 9 vs. 1 days (p < 0.0001), respectively. Admission diagnosis of traumatic brain injury [adjusted odds ratio (OR): 5.6, 95% CI: 1.2-27.0; p = 0.03] and duration of mechanical ventilation (adjusted OR: 1.4, 95% CI: 1.3-1.5; p < 0.0001) were independently associated with A. baumannii aquisition.

CONCLUSION

Acinetobacter baumannii acquisition was common and associated with increased morbidity, but not increased mortality.

Trimethoprim/sulfamethoxazole for Acinetobacter spp.: A review of current microbiological and clinical evidence

Clinicians nowadays are confronted with an epidemic of multidrug-resistant (MDR) Acinetobacter infections and are forced to consider every treatment alternative, including older antibiotic agents, not conventionally used. This review aimed to evaluate the published evidence on the antimicrobial activity and clinical effectiveness of trimethoprim/sulfamethoxazole (TMP-SMX) against Acinetobacter spp. Selected in vitro studies included antimicrobial surveillance reports, microbiological studies regarding the activity of TMP-SMX against MDR Acinetobacter isolates, and clinical studies published after the year 2000. Non-susceptibility rates for Acinetobacter spp. in surveillance studies ranged from 4% to 98.2%; in 23 of 28 studies, non-susceptibility to TMP-SMX was >50% and in a subset of 15 studies non-susceptibility was >70%. In studies regarding MDR Acinetobacter spp., non-susceptibility rates ranged from 5.9% to 100%; however, 19 of 21 studies reported >70% non-susceptibility. Extensively drug-resistant Acinetobacter baumannii complex had total (100%) resistance in five of six studies. Carbapenem-resistant Acinetobacter spp. had non-susceptibility rates to TMP-SMX of >80% in 22 of 26 studies. One study on polymyxin-resistant A. baumannii showed a susceptibility rate of 54.2% (13/24). Only seven case reports evaluated TMP-SMX for Acinetobacter spp. infections, mainly in combination with other agents; all cases were deemed therapeutic successes. Although TMP-SMX is not usually active against Acinetobacter spp., it might be considered in cases where there are no other options.

Risk factors of multidrug-resistant, extensively drug-resistant and pandrug-resistant Acinetobacter baumannii ventilator-associated pneumonia in a Medical Intensive Care Unit of University Hospital in Thailand

Ventilator-associated pneumonia (VAP) caused by Acinetobacter baumannii remains a significant cause of morbidity and mortality. Increasing antimicrobial resistance influences the selection of antibiotic treatment especially pandrug-resistant A. baumannii. A retrospective cohort study was conducted in the Medical Intensive Care Unit to identify the risk factors of VAP caused by multidrug-resistant A. baumannii (MDR-AB), extensively drug-resistant A. baumannii (XDR-AB) and pandrug-resistant A. baumannii (PDR-AB). All 337 adult patients with confirmed A. baumannii VAP were included. The incidence of MDR-AB, XDR-AB and PDR-AB were 72 (21.4%), 220 (65.3%) and 12 (3.6%), respectively. The risk factor for MDR-AB was prior use of carbapenems (OR 5.20; 95% CI 1.41-19.17). Risk factors for XDR-AB were the prior use of carbapenems (OR, 6.30; 95% CI, 1.80-21.97) and a high Sequential Organ Failure Assessment (SOFA) score (OR 1.35; 95% CI 1.07-1.71). In PDR-AB, the risk factors were the prior use of colistin (OR, 155.95; 95% CI, 8.00-3041.98), carbapenems (OR, 12.84; 95% CI, 1.60-103.20) and a high Simplified Acute Physiology Score (SAPS II) (OR 1.10; 95% CI 1.01-1.22). In conclusion, previous exposure to antibiotics and severity of VAP were risk factors of drug-resistant A. baumannii. Judicious use of carbapenems and colistin is recommended to prevent the antimicrobial-resistant strains of this organism.

Risk factors and outcomes of imipenem-resistant Acinetobacter bloodstream infection in North-Eastern Malaysia

OBJECTIVE

To determine the risk factors and outcomes of imipenem-resistant Acinetobacter baumannii (IRAB) bloodstream infection (BSI) cases, since there is very little publication on Acinetobacter baumannii infections from Malaysia.

METHODS

A cross sectional study of 41 cases (73.2%) of imipenem-sensitive Acinetobacter baumanii (ISAB) and 15 cases (26.8%) of IRAB was conducted in a teaching hospital which was located at North-Eastern state of Malaysia.

RESULTS

There was no independent risk factor for IRAB BSI identified but IRAB BSI was significantly associated with longer bacteraemic days [OR 1.23 (95% CI 1.01, 1.50)]. Although prior use of carbepenems and cephalosporin were higher among IRAB than ISAB group, statistically they were not significant. There was no significant difference in term of outcomes between the two groups.

CONCLUSIONS

Although statistically not significant, this analysis compliments previous publication highlighting the importance of appropriate empiric antibiotic usage in hospital especially carbepenems and need further evaluation with bigger subjects.

Surveillance cultures growing carbapenem-Resistant Acinetobacter baumannii predict the development of clinical infections: a retrospective cohort study

BACKGROUND

We aimed to determine the effect of the presence of carbapenem-resistant Acinetobacter baumannii in accordance with surveillance cultures on the subsequent development of clinical infections by this organism.

METHODS

This retrospective cohort study was conducted at a tertiary hospital from January 2010 to November 2011. We included all consecutive patients admitted to the trauma intensive care unit, who had weekly surveillance cultures performed (from rectum, and if intubated, respiratory secretions), and without evidence of A. baumannii infections prior to the collection of the first surveillance culture. Univariable and multivariable analyses were performed using log-binomial regression. Survival analyses were performed using Cox proportional hazards.

RESULTS

Three hundred sixty-four patients were included, of whom 49 (13.5%) had carbapenem-resistant A. baumannii on surveillance cultures. Patients with positive surveillance cultures had 8.4 (95% confidence interval [CI], 5.6-12.7; P < .0001) times the risk of developing a subsequent A. baumannii infection compared with patients who remained negative on surveillance cultures. Multivariable analysis showed significant associations between clinical infection and both positive surveillance cultures (relative risk [RR], 5.9 [95% CI, 3.8-9.3]; P < .0001) and mechanical ventilation (RR, 4.3 [95% CI, 1.03-18.2]; P = .05). On survival analyses, the only variable associated with the development of clinical infections was the presence of positive surveillance cultures (hazard ratio, 16.3 [95% CI, 9.1-29.1]; P < .001).

CONCLUSIONS

Presence of carbapenem-resistant A. baumannii on surveillance cultures is strongly associated with subsequent development of carbapenem-resistant A. baumannii infections. Prevention efforts should be focused at limiting the acquisition of this organism during hospitalization.

Risk factors for nosocomial burn wound infection caused by multidrug resistant Acinetobacter baumannii

Acinetobacter baumannii infections in burn patients may lead to delays in wound healing, graft losses, and development of sepsis. Determining the risk factors for multidrug resistant A. baumannii (MDR-AB) infections is essential for infection control. In the present study, the authors aimed to evaluate risk factors for wound infections caused by A. baumannii in burn patients. The study was conducted at Dicle University Hospital Burn Center, from April 2011 to July 2012, to investigate the risk factors for MDR-AB infections. The data of both the case and control group patients and the result of wound cultures were recorded on a daily basis, on individual forms given for each patient, and analyzed. A total of 30 cases infected with MDR-AB, and 60 uninfected control patients, were included in the study. The mean age (±SD) was 7.7 ± 15.4 years in infected patients and 11.4 ± 16.5 years in uninfected patients. The mean total burn surface area was 13.5 ± 10.9% in uninfected patients and 34.7 ± 16.2% in infected patients. The mean total burn surface area, the abbreviated burn severity index, acute physiological and chronic health evaluation II score, day of admission to hospital, length of hospital stay, first excision day, prior usage of third-generation cephalosporins, and stay in intensive care unit of the infected patients were significantly higher (P < .001) than those of patients without infection. Univariate analysis found that high acute physiological and chronic health evaluation II score, first excision time of wound, invasive device usage, admission day to hospital, and prior usage of broad-spectrum antibiotics were risk factors for nosocomial infections. This study showed that multiple factors contribute to multidrug resistance in A. baumannii. A combination of an early diagnosis of wound infections, appropriate antimicrobial treatments, surgical debridement, and early wound closure may be effective in the management.

Molecular characterisation and control of Acinetobacter baumannii isolates resistant to multi-drugs emerging in inter-intensive care units

BACKGROUND

A nosocomial outbreak of Acinetobacter baumannii (AB) infections occurred among intensive care units (ICU) (surgery, medical, cardiovascular surgery, coronary unit) of Recep Tayyip Erdogan University Medical School (Rize, Turkey) between January 2011 and May 2012. The identification of isolates and clonal relation among them were investigated by molecular techniques.

METHODS

A total of 109 AB isolates were obtained from 64 clinical materials from 54 ICU patients and 3 from the hands of healthcare workers (HCWs) of 42 environmental samples. The isolates were identified by 16S rDNA sequencing and OXA- specific PCR. The clonal relation between isolates was investigated by PFGE methods using ApaI restriction enzyme.

RESULTS

All isolates were determined as AB by 16S rDNA sequencing and OXA-spesific PCR. While the blaOXA-51-like gene was amplified in all isolates, the blaOXA-23-like gene was amplified from 103 isolates. The PFGE pattern generated 9 pulsotypes and showed that the isolates from patients, HCWs, and the environment were genetically related. In 7 of these pulsotypes, there were 107 strains (98%) showing similar PFGE profiles that cannot be distinguished from each other, ranging from 2 to 53. The remaining 2 pulsotypes were comprised of strains closely associated with the main cluster. Two major groups were discovered with similarity coefficient of 85% and above. The first group consisted of 97 strains that are similar to each other at 92.7% rate, and the second group consisted of 12 strains that are 100% identical.

CONCLUSIONS

The common utilization of the blood gas device among ICU was the reason for the contamination. AB strains can remain stable for a long period of time, although due to the disinfection procedures applied in hospitals, there is a small chance that the same clone might reappear and cause another epidemic. For that reason, the resistance profiles of the strains must be continuously followed with amplification-based methods, and these methods should be used to support the PFGE method in the short term.

Molecular characterisation and control of Acinetobacter baumannii isolates resistant to multi-drugs emerging in inter-intensive care units

BACKGROUND

A nosocomial outbreak of Acinetobacter baumannii (AB) infections occurred among intensive care units (ICU) (surgery, medical, cardiovascular surgery, coronary unit) of Recep Tayyip Erdogan University Medical School (Rize, Turkey) between January 2011 and May 2012. The identification of isolates and clonal relation among them were investigated by molecular techniques.

METHODS

A total of 109 AB isolates were obtained from 64 clinical materials from 54 ICU patients and 3 from the hands of healthcare workers (HCWs) of 42 environmental samples. The isolates were identified by 16S rDNA sequencing and OXA- specific PCR. The clonal relation between isolates was investigated by PFGE methods using ApaI restriction enzyme.

RESULTS

All isolates were determined as AB by 16S rDNA sequencing and OXA-spesific PCR. While the blaOXA-51-like gene was amplified in all isolates, the blaOXA-23-like gene was amplified from 103 isolates. The PFGE pattern generated 9 pulsotypes and showed that the isolates from patients, HCWs, and the environment were genetically related. In 7 of these pulsotypes, there were 107 strains (98%) showing similar PFGE profiles that cannot be distinguished from each other, ranging from 2 to 53. The remaining 2 pulsotypes were comprised of strains closely associated with the main cluster. Two major groups were discovered with similarity coefficient of 85% and above. The first group consisted of 97 strains that are similar to each other at 92.7% rate, and the second group consisted of 12 strains that are 100% identical.

CONCLUSIONS

The common utilization of the blood gas device among ICU was the reason for the contamination. AB strains can remain stable for a long period of time, although due to the disinfection procedures applied in hospitals, there is a small chance that the same clone might reappear and cause another epidemic. For that reason, the resistance profiles of the strains must be continuously followed with amplification-based methods, and these methods should be used to support the PFGE method in the short term.

Mathematical model to quantify the effects of risk factors on carbapenem-resistant Acinetobacter baumannii

Carbapenem-resistant Acinetobacter baumannii (CRAB) infections are increasing, and they are associated with an increased risk of mortality in hospitalized patients. Linear regression is commonly used to identify concurrent trends, but it cannot quantify the relationship between risk factors and resistance. We developed a model to quantify the impact of antibiotic consumption on the prevalence of CRAB over time. Data were collected from January 2007 to June 2013 from our institution. Quarterly antibiotic consumption was expressed as defined daily dose/1,000 inpatient days. Six-month prevalence of CRAB was expressed as a percentage of all nonrepeat A. baumannii isolates tested. Individual trends were identified using linear regression. Antibiotic consumption from 2007 to 2011 was input as a step function in a relationship with CRAB. Model fit was evaluated by visual inspection and the residual sum of squares. The final model was validated using the best-fit (95% confidence interval) parameter estimates and antibiotic consumption to predict CRAB prevalence from January 2012 to June 2013. Cefepime, ertapenem, and piperacillin-tazobactam consumption and CRAB prevalence increased significantly over time. CRAB prevalence was best correlated to ertapenem (use sensitive; r2=0.76), and accounting for additional concurrent antibiotic use did not significantly improve model fit. Prospective validation with ertapenem consumption correlated well with CRAB observations, suggesting good predicting ability of the model. Our model provided the quantitative impact of antibiotic consumption on CRAB. We plan to further refine this model to account for multiple risk factors. Interventions should focus on controlling risk factors with the highest impact on resistance.

Risk factors for acquisition of ventilator-associated pneumonia in adult intensive care units

Objective: Ventilator Associated Pneumonia (VAP) has an imperative place amongst nosocomial infections leading to increase morbidity and mortality rates. The present study aimed to determine risk factors for acquisition of ventilator- associated pneumonia in an intensive care unit (ICU).

Methods: A nested case-control study was carried out from September 2007 to June 2008. All 183 patients hospitalized at the adult ICU ward in Be’sat Hospital, Sanandaj city western Iran over a 48 hour period were included. Bacteriologic diagnosis and antibiotic susceptibility patterns were performed based on Edward & Ewing’s methods and CLSI system guidelines.

Results: Of the 149 samples which were taken from endotracheal tubes of 183 patients, 48 cases were diagnosed for VAP with an incidence rate of 26.2%. Mean duration of hospitalization was 23.4±10.2 days. The maximum and minimum antibiotic resistance for the gram negative bacteria was 93.3% for Cefalotin and 50% for Amikacin. The main risk factors for acquisition of ventilator- associated pneumonia were mechanical ventilation (Adjusted OR: 1.55, 95% CI: 1.37-1.74), history of antibiotic consumption (AOR: 8.92, CI: 1.16- 66.66) and fever (AOR: 3.11, CI: 1.22- 7.93).

Conclusions: VAP is significantly related to ICU hospitalization, mechanical ventilation and history of antibiotics consumption. Cefalotin and Amikacin showed the highest and lowest antibiotic resistance against gram negative bacteria respectively.