Major biologic characteristics of Acinetobacter baumannii isolates from hospital environmental and patients' respiratory tract sources

NDM-1- and OXA-23-producing Acinetobacter baumannii in wastewater of a Nigerian hospital

IMPORTANCE

Acinetobacter baumannii is a leading cause of hospital-associated infections globally. A. baumannii reservoirs outside hospital settings are still unknown, and their occurrence in the environment is linked to clinical and anthropogenic activities. Although the risk of transmission of A. baumannii from environmental sources to humans is not fully understood, these sources pose significant risks for the continued dissemination of A. baumannii and their resistance traits. This study provides evidence that diverse and clinically relevant A. baumannii strains, many of which are resistant to carbapenems, are constantly being discharged into the environment through inadequately treated hospital wastewater. We further elucidate potential transmission routes between the environment and clinical infections and demonstrate the high prevalence of carbapenem resistance genes on highly mobile transposons among these strains. Our findings highlight the pressing need to address hospital wastewater as a crucial factor in curtailing the spread of carbapenem-resistant A. baumannii.

Isolation of virulent phages against multidrug-resistant Acinetobacter baumannii recovered from inanimate objects of Jimma Medical Center, Southwest Ethiopia

BACKGROUND

Because of the multidrug resistance features of Acinetobacter baumannii, endurance to diverse conditions, and causing health fatalities in healthcare settings, the global health system is looking for the development of new antimicrobials for such bacteria. As the new antimicrobial drugs pipeline is running dry, it is imperative to look for eco-friendly bio-control strategies. In this regard, phages are one to combat the biofilm producer and MDR A. baumannii. Thus, the study aimed to isolate and examine the role of phages against biofilm producers and MDR A. baumannii from inanimate objects at Jimma Medical Center (JMC), Ethiopia.

METHOD

Institution-based cross-sectional study was conducted from June to November 2019. A total of 309 swab samples were collected from inanimate objects and the environment in JMC. Isolation of A. baumannii, antimicrobial susceptibility testing, and biofilm detection were carried out according to standard protocol. Kirby Bauer disk diffusion and microliter plate were methods for AST and biofilm detection, respectively. Specific phage was isolated and characterized from sewage at JMC compound. The data were analyzed by SPSS version 25.0, and chi-square (X2) cross-tabulation was used to determine the correlation of variables. A P-value of < 0.05 was considered a statistically significant association.

RESULT

A. baumannii from inanimate objects and surfaces of different environments at JMC was detected in 6.5% of the samples. From 20 of the isolates, 85% were biofilm producers, and 60% were MDR. The lytic phage isolated specifically against A. baumannii was found host specific, and thermally stable ranging from 10-50°C. The phage was active against 42% of MDR A. baumannii, 40% of both biofilm-producing and MDR A. baumannii (MDRAB), and 35.3% of the biofilm-producing isolates.

CONCLUSION

The good activity of phages towards MDRAB isolates, its biofilm degradation capability, thermal stability, and host specificity in our study encourages viewing the potential use of phages as a bio-control agent besides the routine cleansing agents. Therefore, we recommend isolation of specific phages in the eradication of MDRAB from health facilities with additional efforts to characterize in detail and assess their efficacy in animal models.

Multidrug-resistant Acinetobacter baumannii in healthcare settings in Africa

The emergence of multidrug-resistant Acinetobacter baumannii is a major concern to healthcare providers and facilities in many parts of the world. This bacterial pathogen is commonly implicated in hospital-acquired infections, particularly in critically ill patients admitted to the intensive care unit (ICU). The extensive use of antibiotics, particularly in ICUs, and the lack of proper infection control interventions in many hospitals have led to an increased emergence of multidrug-resistant A. baumannii. Infections due to multidrug-resistant A. baumannii are associated with prolonged hospital stays and high morbidity and mortality, particularly among hospitalized ICU patients. The lack of antibiotic stewardship programmes in many healthcare facilities has exacerbated the burden of A. baumannii infections in many parts of Africa. This review discusses the prevalence and antibiotic-resistance pattern of the multidrug-resistant A. baumannii, and the possible ways to address or minimise its emergence in healthcare settings in Africa.

Multidrug-Resistant Acinetobacter baumannii in Jordan

Background: Acinetobacter baumannii is a common cause of multi-drug (MDR)-resistant infections worldwide. The epidemiological and molecular characteristics of MDR-A. baumannii in Jordan is not known. Methods: A. baumannii isolates were collected from 2010 to 2020 from three tertiary hospitals in Jordan. Demographic and clinical data, isolates information, antibiotic susceptibility patterns, phenotypic, and molecular characterization of carbapenem resistance genes were performed. Results: A total of 622 A. baumannii isolates were collected during the study period. Most isolates were from males, aged 18−60 years, Jordanian, from infected wounds, and were patients in surgery or critical care units. Among patients from whom A. baumannii was isolated, associated risk factors for MDR were adults over 60, males, critically ill patients and infected wounds (OR 4.14, 2.45, 10, 7, respectively, p < 0.0001). Incidence rates from 2010 to 2015 showed a slight increase in MDR (3.75/1000 to 4.46/1000). Resistance patterns indicated high resistance for most cephalosporins, carbapenems, and fluoroquinolones, moderate resistance for trimethoprim/sulfamethoxazole and ampicillin/sulbactam, low resistance for aminoglycosides and tetracyclines, while colistin and tigecycline, have the lowest resistance rates. 76.8% of A. baumannii isolates were MDR and 99.2% were carbapenem-resistant. All isolates were positive for the OXA-51 gene (100%), 98.5% were positive for the OXA-23 gene, 26.6% for the VIM gene, while KPC and IMP genes were almost not detected (0% and 0.8% respectively). Conclusions: This is the first large, multicentric, prolonged study that provides insights into A. baumannii infections in Jordan. Attention to patients at higher risk is important for early identification. Colistin and tigecycline were the most effective antimicrobials.

Novel Phage Lysin Abp013 against Acinetobacter baumannii

As antimicrobial resistance (AMR) continues to pose an ever-growing global health threat, propelling us into a post-antibiotic era, novel alternative therapeutic agents are urgently required. Lysins are bacteriophage-encoded peptidoglycan hydrolases that display great potential as a novel class of antimicrobials for therapeutics. While lysins against Gram-positive bacteria are highly effective when applied exogenously, it is challenging for lysins to access and cleave the peptidoglycan of Gram-negative bacteria due to their outer membrane. In this study, we identify a novel phage lysin Abp013 against Acinetobacter baumannii. Abp013 exhibited significant lytic activity against multidrug-resistant strains of A. baumannii. Notably, we found that Abp013 was able to tolerate the presence of human serum by up to 10%. Using confocal microscopy and LIVE/DEAD staining, we show that Abp013 can access and kill the bacterial cells residing in the biofilm. These results highlight the intrinsic bacteriolytic property of Abp013, suggesting the promising use of Abp013 as a novel therapeutic agent.

Emerging Status of Multidrug-Resistant Bacteria and Fungi in the Arabian Peninsula

Simple Summary

The incidence and developing status of multidrug-resistant bacteria and fungi, as well as their related mortality, is reviewed by a systematic published literature search from nine countries in the Arabian Peninsula. In order to analyse the emerging status and mortality, a total of 382 research articles were selected from a comprehensive screening of 1705 papers. More than 850 deaths reported since 2010 in the Arabian Peninsula due to the infection of multidrug-resistant bacteria and fungi. Multidrug-resistant bacteria Acinetobacter baumannii, Mycobacterium tuberculosis, Staphylococcus aureus, and fungi Candida auris are the most prevalent and causing high deaths. To control these infections and associated deaths in the Arabian Peninsula, continuous preventive measures, accurate methods for early diagnosis of infection, active surveillance, constant monitoring, developing vaccines, eradicating multidrug resistance modulators, and data sharing among countries are required.

Abstract

We aimed to identify the prevalence and emerging status of multidrug-resistant bacteria and fungi and their associated mortality in nine countries in the Arabian Peninsula. Original research articles and case studies regarding multidrug-resistant bacteria and fungi in the Arabian Peninsula, published during the last 10 years, were retrieved from PubMed and Scopus. A total of 382 studies were included as per the inclusion and exclusion criteria, as well as the PRISMA guidelines, from a thorough screening of 1705 articles, in order to analyse the emerging status and mortality. The emerging nature of >120 multidrug-resistant (MDR) bacteria and fungi in the Arabian Peninsula is a serious concern that requires continuous monitoring and immediate preventive measures. More than 50% (n = 453) of multidrug-resistant, microbe-associated mortality (n = 871) in the Arabian Peninsula was due to MDR Acinetobacter baumannii, Mycobacterium tuberculosis and Staphylococcus aureus infection. Overall, a 16.51% mortality was reported among MDR-infected patients in the Arabian Peninsula from the 382 articles of this registered systematic review. MDR A. baumannii (5600 isolates) prevailed in all the nine countries of the Arabian Peninsula and was one of the fastest emerging MDR bacteria with the highest mortality (n = 210). A total of 13,087 Mycobacterium tuberculosis isolates were reported in the region. Candida auris (580 strains) is the most prevalent among the MDR fungal pathogen in the Arabian Peninsula, having caused 54 mortalities. Active surveillance, constant monitoring, the development of a candidate vaccine, an early diagnosis of MDR infection, the elimination of multidrug resistance modulators and uninterrupted preventive measures with enhanced data sharing are mandatory to control MDR infection and associated diseases of the Arabian Peninsula. Accurate and rapid detection methods are needed to differentiate MDR strain from other strains of the species. This review summarises the logical relation, prevalence, emerging status and associated mortality of MDR microbes in the Arabian Peninsula.

High Carbapenem Resistance Caused by VIM and NDM Enzymes and OprD Alteration in Nonfermenter Bacteria Isolated from a Libyan Hospital

Acinetobacter baumannii and Pseudomonas aeruginosa are among the most prevalent pathogens causing a wide range of serious infections in hospitalized patients and contaminating intensive care units and inanimate surfaces. The purpose of this study was to investigate the mechanism of carbapenem resistance in clinical and hospital environmental isolates of A. baumannii and P. aeruginosa recovered from a Libyan hospital. From a total of 82 Gram-negative bacteria, 8 isolates of A. baumannii and 3 isolates of P. aeruginosa exhibited resistance to imipenem with minimum inhibitory concentrations ranging from 16 to >32 μg/mL. Five isolates of A. baumannii harbored bla_OXA-23 gene, from which three isolates were collected from patients and two from hospital environment. Only one isolate harbored bla_NDM-1 gene, which was responsible for carbapenem resistance in A. baumannii. The OprD gene seems to be disturbed by an insertion sequence (IS) in two isolates and affected by polymorphism in one isolate. Pulsed-field gel electrophoresis results showed high genetic diversity among carbapenemase producing A. baumannii. This study highlights the dissemination of bla_OXA-23 and bla_NDM-1 genes in a Libyan setting. Therefore, infection prevention and control practices, antimicrobial stewardship initiatives, and antimicrobial resistance surveillance systems should be implemented to prevent the wide spread of antimicrobial resistance.

Prevalence and molecular epidemiology of carbapenem-resistant Gram-negative bacilli and their resistance determinants in the Eastern Mediterranean Region over the last decade

Carbapenem resistance in Enterobacteriaceae, Acinetobacter baumannii and Pseudomonas aeruginosa is increasing worldwide, which has led the World Health Organization (WHO) to list these bacteria in the critical priority pathogens group. Infections by such pathogens pose a serious threat to hospitalised patients and are associated with clinical and economic consequences. What worsens the case is the weak pipeline of available antimicrobial agents to treat such infections and the absence of new drugs. The aim of this review was to shed light on all studies tackling carbapenem resistance in Enterobacteriaceae, A. baumannii and P. aeruginosa in the Eastern Mediterranean region, with indication for each country, description of studies timeline, prevalence of carbapenem resistance, and carbapenem resistance-encoding genes detected in these countries.

Phagoburst Response Level of Neutrophils to Septic and Non-Septic Acinetobacter baumannii Isolates

Background:

Acinetobacter baumannii is an opportunistic pathogen causing community-acquired and nosocomial infections. Dissemination of infection to blood causes septicemia associated with serious morbidity and mortality of patients. Neutrophils are essential for the control of A. baumannii infections by different mechanisms, including oxidative burst.

Aims:

This study was conducted as an attempt to determine the effect of septicemic and non-septicemic A. baumannii isolates on the phagoburst response of neutrophils.

Methods:

Neutrophils were isolated from an immunocompetent individual; chronic myeloid leukemia (CML) and lung solid tumor (ST) patients. The phagoburst response of these neutrophils to various strains of A. baumannii isolated from septic and non-septic patients was investigated by flow cytometer.

Results:

The presence of this pathogen lowered the phagoburst response in the different types of neutrophils compared to their response to the opsonized Escherichia coli. The phagoburst response of the neutrophils from the immunocompetent individual was significantly higher than that of neutrophils from the immunodeficient patients when stimulated by the septicemic or nonsepticemic A. baumannii isolates. The isolate type (septicemic or non-septicemic) had no significant effect on the neutrophil phagoburst response of the immunocompetent individual and a significant effect on the phagoburst response of neutrophils from the immunodeficient patients. The phagoburst response of the neutrophils from the immunodeficient patients stimulated by septicemic A. baumannii isolates was significantly lower than that when neutrophils stimulated by the nonsepticemic isolates. Also, there was a significant difference in the phagoburst response of neutrophils from the CML and ST patients when stimulated by the septicemic and non-septicemic isolates. This observation might be due to the combined effect of virulent A. baumannii isolates and the chemotherapy regime the patient was undertaking.

Conclusion:

The results suggest that both the isolate type and the source of neutrophils have a significant effect on the neutrophil phagoburst response. The potential virulence of the septicemic A. baumannii isolates and dissemination to blood may be dependent on the host’s immune status and the neutrophils phagoburst response.

Design of a Multi-epitope Vaccine Against Acinetobacter baumannii Using Immunoinformatics Approach

Acinetobacter baumannii is one of the most successful pathogens causing nosocomial infections and has significantly multidrug-resistant. So far, there are no certain treatments to protect against infection with A. baumannii, therefore an effective A. baumannii vaccine needed. The purpose of this study was to predict antigenic epitopes of CarO protein for designing the A. baumannii vaccine using immunoinformatics analysis. CarO protein is one of the most important factors in the resistance against the antibiotic Carbapenem. In this study, T and B-cell epitopes of CarO protein were predicted and screened based on the antigenicity, toxicity, allergenicity features. The epitopes were linked by suitable linkers. Four different adjuvants were attached to the vaccine constructs which among them, vaccine construct 3 was chosen to predict the secondary and the 3D structure of the vaccine. The refinement process was performed to improve the quality of the 3D model structure; the validation process is performed using the Ramachandran plot and ProSA z-score. The designed vaccine's binding affinity to six various HLA molecules and TLR 2 and TLR4 were evaluated by molecular docking. Finally, in silico gene cloning was performed in the pET28a (+) vector. The findings suggest that the vaccine may be a promising vaccine to prevent A. baumannii infection.

A 5-year surveillance on antimicrobial resistance of Acinetobacter isolates at a level-I trauma centre of India

INTRODUCTION:

Acinetobacter spp. has emerged as a major cause of nosocomial outbreaks. Multiple antibiotic resistance is an important problem in Acinetobacter isolates in recent years. The aim of this study was to evaluate the rate of antimicrobial resistance and changes in resistance pattern over a period of 5 years (2012–2016) in Acinetobacter spp. isolated from trauma patients.

MATERIALS AND METHODS:

Acinetobacter spp. was identified by VITEK 2 and antibiotic susceptibility of isolates was investigated by disc-diffusion method and VITEK 2 automated system. Interpretation of susceptibility results was based on the Clinical and Laboratory Standards Institute guidelines.

RESULTS:

Out of the total 16,210 isolates obtained throughout the period of 5 years, Acinetobacter spp. accounted for 3744 (28.9%). Out of which, the species which was maximally isolated was Acinetobacterbaumannii (98.5%), followed by Acinetobacterlwoffii (1.4%) and Acinetobacterhemolyticus (0.1%). The highest number of clinical isolates of Acinetobacter were recovered from neurosurgical ward (n = 1210), followed by the neurosurgical intensive care unit (ICU) (n = 1000) and surgical ICU (n = 948) and the most common sample of Acinetobacter isolation was from tracheal aspirate (37.1%), followed by wound swab (18.8%). The highest level of resistance was observed against ciprofloxacin (96%), followed by cefepime (95%), ceftazidime (95%), piperacillin (95%), and amikacin (92%). The trend of antibiotic resistance was found to be statistically significant (P < 0.001) for most of the antibiotics being tested such as amikacin and carbapenems.

CONCLUSION:

The high rate of antibiotic resistance of the Acinetobacter strains indicated that there is an urgent need for controlled antibiotic usage and appliance of hospital infection control measures.

Effect of prior receipt of antibiotics on the pathogen distribution: a retrospective observational cohort study on 27,792 patients

Background

There have been no systematic studies of microbiological differences before and after antibiotics treatment. The aim of this study was to evaluate the effect of prior receipt of antibiotics on the microorganism distribution.

Methods

A retrospective, observational cohort study was conducted in a 3200-bed tertiary, referral, teaching hospital in eastern China. During a 2-year period, all hospitalized patients treated with antimicrobial agents were enrolled in this study. Among 48,692 patients evaluated, the 27,792 (57.1%) who were sampled within 2 days before or after administration of the first dose of antimicrobial agents were included. Distribution of clinical specimens and the microorganism were compared between before and after antibiotic drug treatment groups.

Results

Compared to specimens taken after antibiotics exposure, specimens taken before antibiotics exposure had a higher proportion of blood and urine specimens and a higher culture positive rate (all P < 0.001). Higher percentages of Staphylococcus aureus (9.9% vs. 8.5%, P = 0.041), non-fermenting bacteria (27.7% vs. 19.9%, P < 0.001), and fungi (8.4% vs. 4.0%, P < 0.001) were isolated from the group after antibiotics exposure, while the percentages of Streptococcus spp. (4.8% vs. 2.7%, P < 0.001), Haemophilus influenzae (2.3% vs. 0.8%, P < 0.001), and Moraxella catarrhalis (0.7% vs. 0.1%, P < 0.001) were higher in the group before antibiotics exposure. Further analysis found significant differences of microbes derived from respiratory secretions, blood or urine samples. We found, after antibiotics exposure, the separation rate of non-fermenting bacteria was significantly increased (all P < 0.05), and the separation rate of Candida spp. was higher, with statistical significance in airway secretion and urine samples (both P < 0.05), but the separation rate of Staphylococcus aureus among the three groups was not affected by antibiotics. In addition, the isolation rate of Streptococcus spp. in blood and urine samples decreased significantly (both P < 0.05) after antibiotics exposure. Interestingly, no statistical difference was found for microbes isolated from body fluid specimens between the two groups.

Conclusions

The outcome revealed that antibiotic-insensitive organisms such as non-fermentative bacteria and fungi were more frequently isolated after antibiotics exposure. However, this trend might be specimen dependent and was not obvious in body fluid specimens.

Prevalence of Multi-drug Resistant Acinetobacter baumannii (MDRAB) in Amman Jordan During 2018

PURPOSE

Acinetobacter baumannii is an opportunistic pathogen, and is among the most problematic nosocomial infections as well as community-acquired infections. This retrospective study was conducted as an attempt to determine the prevalence of multidrug-resistant A. baumannii (MDRAB) isolates from the north and central Jordan area during 2018.

METHODS

Patients' records provided by an accredited central private laboratory located in Amman, were examined for A. baumannii isolates identified during this period. The isolates were identified to the species level using the API-10S system and the antimicrobial sensitivity testing was determined using the Kirby-Bauer disc diffusion method.

RESULTS

A total of 43 unduplicated isolates were obtained and classified according to clinical sampling source into: Group I (blood), Group II (urine) and Group III (wound, pus, sputum, bedsore and others). Total MDRAB isolates recorded were 29 (67.4 %). Resistance to imipenem was found to be 36% and 94% among groups II and III, respectively, and resistance to meropenem was 60% and 88% among the same groups, respectively.

CONCLUSION

Antimicrobial stewardship programs at a national scale are needed to calculate the actual proportion of MDRAB in the country and to combat its increasing emergence and decrease the magnitude of antibiotic resistance.

Understanding the Epidemiology of Multi-Drug Resistant Gram-Negative Bacilli in the Middle East Using a One Health Approach

In the last decade, extended-spectrum cephalosporin and carbapenem resistant Gram-negative bacilli (GNB) have been extensively reported in the literature as being disseminated in humans but also in animals and the environment. These resistant organisms often cause treatment challenges due to their wide spectrum of antibiotic resistance. With the emergence of colistin resistance in animals and its subsequent detection in humans, the situation has worsened. Several studies reported the transmission of resistant organisms from animals to humans. Studies from the middle east highlight the spread of resistant organisms in hospitals and to a lesser extent in livestock and the environment. In view of the recent socio-economical conflicts that these countries are facing in addition to the constant population mobilization; we attempt in this review to highlight the gaps of the prevalence of resistance, antibiotic consumption reports, infection control measures and other risk factors contributing in particular to the spread of resistance in these countries. In hospitals, carbapenemases producers appear to be dominant. In contrast, extended spectrum beta lactamases (ESBL) and colistin resistance are becoming a serious problem in animals. This is mainly due to the continuous use of colistin in veterinary medicine even though it is now abandoned in the human sphere. In the environment, despite the small number of reports, ESBL and carbapenemases producers were both detected. This highlights the importance of the latter as a bridge between humans and animals in the transmission chain. In this review, we note that in the majority of the Middle Eastern area, little is known about the level of antibiotic consumption especially in the community and animal farms. Furthermore, some countries are currently facing issues with immigrants, poverty and poor living conditions which has been imposed by the civil war crisis. This all greatly facilitates the dissemination of resistance in all environments. In the one health concept, this work re-emphasizes the need to have global intervention measures to avoid dissemination of antibiotic resistance in humans, animals and the environment in Middle Eastern countries.

Carbapenem-resistant Acinetobacter baumannii from Air and Patients of Intensive Care Units

To understand the molecular epidemiology and antibiotic resistance of air and clinical isolates of Acinetobacter baumannii, the intensive care unit settings of a hospital in Northern China were surveyed in 2014. Twenty non-duplicate A. baumannii isolates were obtained from patients and five isolates of airborne A. baumannii were obtained from the wards’ corridors. Pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were used to analyze the homology relationships of isolates. Resistance and resistance genes were detected by drug susceptibility test and PCR. The results demonstrated that all isolates can be classified into eight PFGE types and four sequence types (ST208, ST195, ST369 and ST530). A pair of isolates from patients (TAaba004) and from the air (TAaba012) that share 100% similarity in PFGE was identified, indicating that air might be a potential and important transmission route for A. baumannii. More than 80% of the isolates were resistant to carbapenems and aminoglycoside antibiotics. Twenty-four isolates, which were resistant to carbapenems, carried the bla_OXA-23-like gene. The data indicated that air might be an alternative way for the transmission of A. baumannii. Hospitals should pay more attention to this route, and design new measures accordingly.

Molecular epidemiology of multidrug-resistant Acinetobacter baumannii infection in two hospitals in Central Brazil: the role of ST730 and ST162 in clinical outcomes

PURPOSE

Acinetobacter baumannii is a major cause of multidrug-resistant nosocomial infections. The characteristics of A. baumannii at two hospitals in a city in Central Brazil are described by analysing the phenotypes and molecular profiles of isolates recovered from 87 patients.

METHODOLOGY

The isolates were identified and their antimicrobial susceptibility was evaluated using the the Bact/Alert 3D and Vitek2 methods. Patients' clinical data were obtained from medical files. Genes associated with resistance to carbapenems were analysed by multilocus sequence typing, clinical and bacteriological variables were analysed by descriptive statistics, and logistic models were generated to adjust the associations.

RESULTS

Sixty-four (73.5 %) out of 87 A. baumannii isolates analysed were from patients in intensive care. The mortality rate was 43.7 %. Eighty (91.9 %) isolates were resistant to imipenem and 86 were susceptible to colistin (98.8 %). The blaOXA-23 gene (78.2 %) and its upstream insertion ISAba1 (55.2 %) were predominant, followed by blaOXA-24 (55.2 %) and blaOXA-143 (28.7 %). The blaOXA-23 gene and ISAba1 were independently associated with resistance to imipenem (P<0.05). There were 13 different sequence types (STs) among the 35 isolates. ST1 (nine; 25.7 %), ST162 (eight; 22.8 %) and ST730 (six; 17.1 %) were the most common, and four new STs were identified. The isolates were grouped into five clonal complexes (CC1, CC15, CC79, CC108 and CC162) plus a singleton using eburst.

CONCLUSION

Respiratory infection, age >60 years and use of noradrenaline were factors associated with fatality. ST730 (CC79) was associated with higher mortality (P<0.05) and ST162 (CC162) was associated with increased survival probability (P<0.05).

Survival of ESKAPE pathogen Acinetobacter baumannii in water of different temperatures and pH

Bacterium Acinetobacter baumannii is an emergent pathogen associated with nosocomial infections, which can be also found in natural waters. The impact of ecological factors on A. baumannii is insufficiently investigated. The aim was to examine the influence of temperatures (-20 to 80 °C) and pH values (2 to 12) on the survival of environmental and clinical isolates of A. baumannii in nutrient-deprived spring water (SW) and nutrient-rich diluted nutrient broth during 5 months. A. baumannii successfully survived at -20 to 44 °C and neutral pH for 5 months, which is consistent with the persistence of this pathogen in the hospital environment. At temperatures 50 to 80 °C the survival of A. baumannii ranged from 5 days to 5 min. The pH 2 was the most lethal with survival time up to 3 hours, suggesting that acidic conditions are promising for disinfection of water contaminated with A. baumannii. Although the type of media was not statistically significant for long-time survival, the extensively resistant or pandrug-resistant isolates survived better in SW than susceptible or multidrug-resistant isolates. Two distinct colony phenotypes were recorded at extreme temperatures and pH values. The results of this study provide insight into the behaviour of this emerging pathogen in the environment.

Epidemiology of common resistant bacterial pathogens in the countries of the Arab League

No uniformly organised collection of data regarding antimicrobial resistance has occurred in the countries of the Arab League. 19 countries of the Arab League have published data for antimicrobial susceptibility for the WHO priority organisms, and seven of 14 of these organisms are included in this Review (Escherichia coli, Klebsiella spp, Pseudomonas aeruginosa, Acinetobacter baumannii, Salmonella spp, Staphylococcus aureus, and Streptococcus pneumoniae). Although E coli and Klebsiella spp resistance to third-generation cephalosporins is common in all countries, with prevalence reaching more than 50% in Egypt and Syria, carbapenem resistance is emerging, albeit with a prevalence of less than 10%. Conversely, a large amount of carbapenem resistance has been reported for P aeruginosa and A baumannii across the Arab League, reaching 50% and 88% of isolates in some countries. As for Salmonella spp, the prevalence of fluoroquinolone resistance has exceeded 30% in several areas. With regards to the Gram-positive pathogens, the prevalence of meticillin resistance in S aureus is reported to be between 20% and 30% in most countries, but exceeds 60% in Egypt and Iraq. The prevalence of penicillin non-susceptibility among pneumococci has reached more than 20% in Algeria, Egypt, Morocco, Saudi Arabia, and Tunisia. These findings highlight the need for structured national plans in the region to target infection prevention and antimicrobial stewardship.

Genomic and Biochemical Characterization of Acinetobacter Podophage Petty Reveals a Novel Lysis Mechanism and Tail-Associated Depolymerase Activity

The increased prevalence of drug-resistant, nosocomial Acinetobacter infections, particularly from pathogenic members of the Acinetobacter calcoaceticus-baumannii complex, necessitates the exploration of novel treatments such as phage therapy. In the present study, we characterized phage Petty, a novel podophage that infects multidrug-resistant Acinetobacter nosocomialis and Acinetobacter baumannii Genome analysis reveals that phage Petty is a 40,431-bp ϕKMV-like phage, with a coding density of 92.2% and a G+C content of 42.3%. Interestingly, the lysis cassette encodes a class I holin and a single-subunit endolysin, but it lacks canonical spanins to disrupt the outer membrane. Analysis of other ϕKMV-like genomes revealed that spaninless lysis cassettes are a feature of phages infecting Acinetobacter within this subfamily of bacteriophages. The observed halo surrounding Petty's large clear plaques indicated the presence of a phage-encoded depolymerase capable of degrading capsular exopolysaccharides (EPS). The product of gene 39, a putative tail fiber, was hypothesized to possess depolymerase activity based on weak homology to previously reported phage tail fibers. The 101.4-kDa protein gene product 39 (gp39) was cloned and expressed, and its activity against Acinetobacter EPS in solution was determined. The enzyme degraded purified EPS from its host strain A. nosocomialis AU0783, reducing its viscosity, and generated reducing ends in solution, indicative of hydrolase activity. Given that the accessibility to cells within a biofilm is enhanced by degradation of EPS, phages with depolymerases may have enhanced diagnostic and therapeutic potential against drug-resistant Acinetobacter strains.IMPORTANCE Bacteriophage therapy is being revisited as a treatment for difficult-to-treat infections. This is especially true for Acinetobacter infections, which are notorious for being resistant to antimicrobials. Thus, sufficient data need to be generated with regard to phages with therapeutic potential, if they are to be successfully employed clinically. In this report, we describe the isolation and characterization of phage Petty, a novel lytic podophage, and its depolymerase. To our knowledge, it is the first phage reported to be able to infect both A. baumannii and A. nosocomialis The lytic phage has potential as an alternative therapeutic agent, and the depolymerase could be used for modulating EPS both during infections and in biofilms on medical equipment, as well as for capsular typing. We also highlight the lack of predicted canonical spanins in the phage genome and confirm that, unlike the rounding of lambda lysogens lacking functional spanin genes, A. nosocomialis cells infected with phage Petty lyse by bursting. This suggests that phages like Petty employ a different mechanism to disrupt the outer membrane of Acinetobacter hosts during lysis.

Antimicrobial resistance and putative virulence genes of Pseudomonas aeruginosa isolates from patients with respiratory tract infection

Introduction

Pseudomonas aeruginosa is a common agent causing community acquired and nosocomial respiratory tract infections, with particularly life-threatening manifestations in patients who are immunocompromised of who have cystic fibrosis. This study investigated the occurrence of extended-spectrum β-lactamases (ESBLs) and metallo β-lactamase (MBL) in association with important putative virulence genes and genotypes variation among P. aeruginosa isolates from respiratory tract infection of Jordanian patients.

Methods

Over a period of 8-month, a total of 284 respiratory tract samples were obtained from patients diagnosed with respiratory tract infection while attending the Pulmonary Clinic/Intensive Care Unit, Jordan University Hospital (JUH). At the time of sampling most were inpatients (86.9%). Samples were cultured specifically for P. aeruginosa.

Results

A total of 61/284 (21.5%) P. aeruginosa isolates were recovered from respiratory samples of patients. The percentage of MDR P. aeruginosa isolates was 52.5%, and all isolates were susceptible to colistin with lower rates of susceptibility to other tested antibiotics. Positive genes of bla_CTX-M, bla_VEB, bla_TEM, bla_GES and bla_SHV were detected in 68.9%, 18.9%, 18.9%, 15.6% and 12.5% of isolates, respectively. Genotyping revealed no significant genetic relationship among MDR P. aeruginosa isolates from hospitalized patients as judged by the constructed dendrogram and the presence of 14 genotypic groups. The percentages of the virulence genes algD, lasB, toxA, exoS, and exoU among P. aeruginosa isolates were 98%, 98%, 80%, 33% and 33%, respectively, and 87% of isolates produced pyocyanin.

Conclusion

The present study demonstrates high occurrence of MDR P. aeruginosa isolates carrying bla_CTX-M genes. No specific associations were found between antibiotic resistance, virulence genes and genotypes among MDR isolates.

Evaluating Adherence of Health-Care Team to Standard Guideline of Colistin Use at Intensive Care Units of a Referral Hospital in Shiraz, Southwest of Iran

Purpose: To evaluate colistin use according to global standard drug consumption in intensive care units of a referral hospital in Shiraz, Iran

Methods: A prospective, interventional study was performed during an 11 month period on 100 patients admitted to ICUs of a teaching hospital being treated with colistin for at least 3 subsequent doses. Required demographic, clinical, and paraclinical data were gathered by a pharmacist. Fifteen indexes were considered to evaluate colistin use. A clinical pharmacist reviewed indication and dose of colistin at the time of prescribing this agent.

Results: In our study population, pneumonia (69%) was the main indication of colistin. In 87% of patients, colistin administration was based on microbiological laboratory evidence. Continuation of therapy was inappropriate in 5% of cases. By the intervention of the clinical pharmacist, colistin was discontinued in all patients in whom empirical therapy was continued incorrectly. None of the patients received loading dose of colistin. The maintenance dose, dose interval, and duration of treatment of colistin were appropriate in 76%, 71%, and 100% of patients, respectively. For none of the patients, the pharmacokinetic dosing method was used. In all patients, serum creatinine and WBC count were evaluated on daily basis. The sum indexes of colistin use were relevant to standard guidelines in 67.33% of the cases.

Conclusion: The results of this study highlight the necessity of the pharmaceutical care team participation in all stages of treatment with antibiotics. After pharmacist interventions, some criteria of colistin utilization were corrected and brought closer to standard values.

Correlation between ability of biofilm formation with their responsible genes and MDR patterns in clinical and environmental Acinetobacter baumannii isolates

Acinetobacter baumannii potential to form biofilm and exhibit multiple antibiotic resistances may be responsible in its survival in hospital environment. Accordingly, our study was aimed to determine the correlation between ability of biofilm formation and the frequency of biofilm related genes with antibiotic resistance phenotypes, and also the categorization of their patterns in clinical and environmental isolates. A total of 75 clinical and 32 environmental strains of the A. baumannii were collected and identified via API 20NE. Antibiotic susceptibility was evaluated by disk diffusion and microdilution broth methods. Biofilm formation assay was performed by microtiter plate method. OXA types and biofilm related genes including Bla_OXA-51, Bla_OXA-23, Bla_OXA-24, Bla_OXA-58, bap, bla_PER-1, and ompA were amplified by PCR. The rate of MDR A. baumannii in clinical isolates (100%) was higher than environmental (81.2%) isolates (p < 0.05). Among 10 antibiotypes, the predominant resistance pattern in clinical and environmental isolates was antibiotypes I (85.3 and 78.1%, respectively). Analysis of the frequency of bla_OXA-23 gene revealed a statistically significant difference between clinical (85.3%) and environmental (68.7%) isolates (p < 0.05). The prevalence of strong biofilm producers in clinical and environmental isolates were 31.2%-58.7%, respectively. In the clinical and environmental isolates, the frequencies of ompA, bla_RER-1 and bap genes were 100%, 53.3%, 82.7% and 100%, 37.5%, 84.4% respectively. Statistical analysis revealed a significant correlation between the frequency of MDR isolates and biofilm formation ability (p = 0.008). The high frequency of antibiotype I would be indicated that an outbreak has been happened earlier and an endemic strain is currently being settled in the hospital environment. It would be suggested that if there was no difference in the frequency of pattern I and biofilm formation ability between clinical and environmental isolates, it is a critical point representing the higher risk of bacterial transmission from environment to the patients. The resulting data would be assisted in the improvement of disinfection strategies to better control of nosocomial infections. One dominant resistance pattern has shown among clinical and environmental isolates. The frequency of blaOXA-23 had significant difference between clinical and environmental isolates. The presence of bap gene in the A. baumannii isolates was associated with biofilm formation. There was a significant correlation between multiple drug resistance and biofilm formation. The clinical isolates had a higher ability to form strong biofilms compared to the environmental samples.

Silver-embedded screens in the intensive care unit. A new tool to control multi-drug resistant bacterial cross-transmission

The purpose of this study was to assess the effectiveness of silver-embedded surfaces (BactiBlock®) to prevent surface colonization by multi-resistant bacteria (MRB) and to reduce the incidence of MRB colonization and infection in patients admitted to an intensive care unit (ICU). A 6-month prospective observational study in a 24-bed mixed ICU divided into two identical subunits (12 beds each) was designed. Seven solid mobile screens were placed in one of the subunits while in the other cloth screens remained. Solid screens were constructed with high-density polyethylene embedded in Bactiblock®. To evaluate the effectiveness of screens coated with Bactiblock®, number of MRB isolates on screens were compared for 6 months. Likewise, numbers of new patients and ICU-stays with MRB colonization in the two subunits were compared. One hundred forty screen samples were collected in 10-point prevalent days. MRB were detected on 28 (20.0%) samples. Over the 70 samples taken on cloth folding screens, MRB were detected in 25 (35.7%), while only 3 (4.3%) of the 70 samples taken on Bactiblock® screens were positive for MRB (p < 0.001). The unit with Bactiblock® screens presented fewer number of ICU stays with MRB colonization (27.8% vs 47.1%; p < 0.001). No significant differences were found in the global incidence of MRB nosocomial infection. The presence of Bactiblock® embedded in solid folding screens avoided MRB surface colonization and reduced MRB transmission to patients admitted to critical care units, proving to be an useful tool in the control of MRB.

Current Trends of Drug Resistance Patterns of Acinetobacter baumannii Infection in Blood Transfusion-dependent Thalassemia Patients

Objective

The present study aimed to evaluate the current trends of drug resistance patterns of Acinetobacter baumannii infection in blood transfusion-dependent thalassemia patients.

Study Design

This study was a cross sectional study, conducted at the Liaquat University of Medical and Health Sciences, Jamshoro/Hyderabad, Sindh, Pakistan from October 2014 to January 2016.

Subjects and Methods

Of 921 blood samples, A. baumannii strains were isolated from 100 blood samples. Blood samples were processed for the isolation, identification, and drugs sensitivity as per the Clinical and Laboratory Standards Institute. A. baumannii strains were identified by microbiological methods and Gram's staining. API 20 E kit (Biomeriuex, USA) was also used for identification. Data were analyzed on Statisti × 8.1 (USA).

Results

Mean ± standard deviation age was 11.5 ± 2.8 years. Nearly 70% were male and 30% were female (P = 0.0001). Of 921 blood transfusion-dependent thalassemia patients, 100 (10.8%) patients showed growth of A. baumannii. Drug resistance was observed against the ceftazidime, cefixime, cefepime, imipenem, meropenem, amikacin, minocycline, tigecycline, and tazocin except for the colistin.

Conclusion

The present study reports drug-resistant A. baumannii in blood transfusion-dependent thalassemia patients. National multicenter studies are recommended to estimate the size of the problem.

Is airborne transmission of Acinetobacter baumannii possible: A prospective molecular epidemiologic study in a tertiary care hospital

BACKGROUND

Understanding the dynamics of aerial spread of Acinetobacter may provide useful information for production of effective control measurements. We investigated genetic relationships between air and clinical isolates of Acinetobacter baumannii in an intensive care unit (ICU) setting.

METHODS

We conducted a prospective surveillance study in a tertiary care hospital for 8 months. A total of 186 air samples were taken from 2 ICUs. Clonal characteristics of air isolates were compared with the prospective clinical strains and the previously isolated strains of ICU patients over a 23-month period.

RESULTS

Twenty-six (11.4%) air samples yielded A baumannii, of which 24 (92.3%) isolates were carbapenem-resistant. The Acinetobacter concentration was the highest in bedside sampling areas of infected patients (0.39 CFU/m³). Air isolates were clustered in 13 genotypes, and 7 genotypes (including 18 air strains) were clonally related to the clinical strains of 9 ICU patients. One clone continued to be cultured over 27 days in ICU air, and air isolates could be clonally related to 7-week retrospective and approximately 15-week prospective clinical strains.

CONCLUSIONS

The results of this study suggest that infected patients could spread significant amounts of Acinetobacter to ICU air. These strains could survive in air for some weeks and could likely still infect new patients after some months. Special control measurements may be required against the airborne spread of Acinetobacter in ICUs.

Clonal relatedness and biofilm formation of OXA-23-producing carbapenem resistant Acinetobacter baumannii isolates from hospital environment

Carbapenem-resistant Acinetobacter baumannii (CRAB) is a serious threat for hospitalized patients and it can survive for long periods in hospital settings, particularly on inanimate surfaces. The environment occupied by these resistant and resilient isolates may act as a reservoir for cross-colonization and outbreaks. Here, we aimed to determine the distribution of CRAB in the hospital environment and to characterize their clonal relatedness, susceptibility profile, carriage of bla_OXA genes, and biofilm formation. A total of 1080 samples were collected from various environmental surfaces and equipment of two referral hospitals in Tehran, Iran. The A. baumannii isolates were subjected to gyrB multiplex PCR, antibiotic susceptibility testing, biofilm formation assay, pulsed field gel electrophoresis (PFGE), and multiplex PCR for bla_OXA-58, bla_OXA-24, and bla_OXA-23 genes. Eighteen Acinetobacter spp. were isolated; 8 were identified as A. baumannii and 10 as A. lwoffii. Five of A. baumannii isolates were CRAB and exhibited the multidrug-resistant (MDR) phenotype as well. All CRAB isolates produced biofilm, albeit with different levels. Four of CRAB isolates harbored the bla_OXA-23. The CRAB isolates were clustered into 3 distinct pulsotypes (PTs). The CRAB isolates belonging to PT1 were detected in two geographically distinct hospitals whereas those belonging to PT3 were found in two different units of same hospital. This study revealed the presence of clonally related OXA-23-producing CRAB in high risk units of referral hospitals as inter- or intra-hospital dissemination. The distribution of multiresistant A. baumannii on several surfaces and areas may increase the risk of transmission of resistant isolates to vulnerable patients.

Acinetobacter infections prevalence and frequency of the antibiotics resistance: comparative study of intensive care units versus other hospital units

INTRODUCTION

This study aims to determine the Acinetobacter sp clinical isolates frequency and its antibiotic susceptibility pattern by comparing results obtained from the Intensive Care Units (ICUs) to that of other units at the Mohammed V Military Teaching Hospital in Rabat.

METHODS

This is a retrospective study over a 2-years period where we collected all clinical isolates of Acinetobacter sp obtained from samples for infection diagnosis performed on hospitalized patients between 2012 to 2014.

RESULTS

During the study period, 441 clinical and non-repetitive isolates of Acinetobacter sp were collected representing 6.94% of all bacterial clinical isolates (n = 6352) and 9.6% of Gram negative rods (n = 4569). More than a half of the isolates were from the ICUs and were obtained from 293 infected patients of which 65, 2% (191 cases) were males (sex ratio = 1.9) and the median age was 56 years (interquartile range: 42-68 years). Acinetobacter clinical isolates were obtained from respiratory samples (44.67%) followed by blood cultures (14.51%). The resistance to ciprofloxacin, ceftazidime, piperacillin / tazobactam, imipenem, amikacin, tobramycin, netilmicin, rifampicin and colistin was respectively 87%, 86%, 79%, 76%; 52%, 43%, 33% 32% and 1.7%. The difference in resistance between the ICUs and the other units was statistically significant (p <0.05) except for colistin, tetracycline and rifampicin.

CONCLUSION

This paper shows that solving the problem of prevalence and high rate of multidrug resistant Acinetobacter infection which represents a therapeutic impasse, requires the control of the hospital environment and optimizing hands hygiene and antibiotics use in the hospital.

Point-prevalence survey of healthcare-associated infections in Beijing, China: a survey and analysis in 2014

BACKGROUND

Point-prevalence studies can identify priorities for infection control.

AIM

In May 2014, the Beijing Nosocomial Infection Control and Quality Improvement Centre organized a point-prevalence survey in 124 acute care hospitals in Beijing province. By analysing the survey results and factors affecting the point prevalence of healthcare-associated infections (HCAIs) in secondary and tertiary acute care hospitals in a certain area of China, this study provides evidence and reference to monitor HCAIs in a wide variety of hospitals.

METHODS

An epidemiological cross-sectional survey conducted by infection control practitioners was used to assess the point-prevalence rate of HCAIs by reviewing cases and performing bedside surveys.

FINDINGS

In total, 124 hospitals and 61,990 patients were surveyed, and 1389 (2.2%) HCAIs were diagnosed in 1294 (2.1%) patients. Respiratory tract infections were the most common HCAIs (54.4%, 51.7-56.9%), followed by urinary tract infections (15.0%, 13.2-16.9%), gastrointestinal tract infections (7.7%, 6.3-9.1%), surgical site infections (6.3%, 5.1-7.6%) and bloodstream infections (5.5%, 4.3-6.8%). In this survey, the top three pathogens were Pseudomonas aeruginosa, Acinetobacter baumannii and Escherichia coli. Rates of central vein catheter insertion, urethral catheterization and mechanical ventilation were 9.9%, 12.4% and 3.8%, respectively. Overall, 23.7% of the patients underwent surgery on or before the date of the survey. HCAIs were present in 14.5% of intensive care unit patients, 2.3% of medical patients and 2% of surgical patients. Diarrhoea was found in 0.8% of the assessed cases; however, tests for Clostridium difficile are not routinely available in China.

CONCLUSION

In areas with limited personnel and resources, regular investigation of the point prevalence of HCAIs can be performed in lieu of comprehensive monitoring to elucidate risk factors and disease burdens of HCAIs.

Clinical isolates of Acinetobacter baumannii from a Portuguese hospital: PFGE characterization, antibiotic susceptibility and biofilm-forming ability

Acinetobacter baumannii is an emerging pathogen associated with nosocomial infections that in addition has shown an increasing resistance to antibiotics. In this work the genetic diversity of A. baumannii isolates from a Portuguese hospital, their antibiotic resistance profiles and ability to form biofilms was studied. Seventy-nine clinical A. baumannii isolates were characterized by pulsed-field gel electrophoresis (PFGE) with 9 different PFGE profiles being obtained. Concerning the antimicrobial susceptibility, all A. baumannii isolates were resistant to 12 of the 17 tested antibiotics and classified as multidrug-resistant (MDR). In addition, 74.7% of the isolates showed biofilm formation ability, however no statistical significance with antibiotic resistance was observed. In contrast, urine samples isolates were more likely to form biofilms than strains isolated from other sources. Our findings highlight the high number of MDR A. baumannii isolates and the importance of the formation of biofilms as a potential virulence factor.

Multidrug Resistance Related to Biofilm Formation in Acinetobacter baumannii and Klebsiella pneumoniae Clinical Strains from Different Pulsotypes

The emergence of Acinetobacter baumannii and Klebsiella pneumoniae strains in the hospital environment has been associated with the presence of multiple genetic elements, virulence factors and the ability to form biofilms. This study evaluated the biofilm formation ability of clinical and environmental A. baumannii and K. pneumoniae strains, isolated from various sources and presenting different molecular characteristics, resistance profiles and pulsed-field gel electrophoresis patterns. Fifty-three isolates were recovered from 2009 to 2014 in a Brazilian university hospital. Investigation of biofilm formation was performed for 10 strains of each species assessed by an initial adhesion assay, biofilm cell concentration and biofilm biomass, evaluated by quantitative assays in replicates, in three independent experiments. All strains of A. baumannii were able to attach to polystyrene plates, although two strains adhered to a lesser degree than the control. K. pneumoniae strains showed opposite behaviour, where only three strains adhered significantly when compared to the control. Quantitative evaluation revealed that in five A. baumannii and four K. pneumoniae isolates the biomass production could be characterised as moderate. None of the isolates were strong biofilm producers. Our results demonstrate: (1) biofilm formation is a heterogeneous property amongst A. baumannii and K. pneumoniae clinical strains and it was not associated with certain clonal types; (2) no relationship between multidrug resistance and biofilm production was observed; (3) more virulent K. pneumoniae strains tended to present higher production of biofilm.

Novel phage lysin capable of killing the multidrug-resistant gram-negative bacterium Acinetobacter baumannii in a mouse bacteremia model

Acinetobacter baumannii, a Gram-negative multidrug-resistant (MDR) bacterium, is now recognized as one of the more common nosocomial pathogens. Because most clinical isolates are found to be multidrug resistant, alternative therapies need to be developed to control this pathogen. We constructed a bacteriophage genomic library based on prophages induced from 13 A. baumannii strains and screened it for genes encoding bacteriolytic activity. Using this approach, we identified 21 distinct lysins with different activities and sequence diversity that were capable of killing A. baumannii. The lysin (PlyF307) displaying the greatest activity was further characterized and was shown to efficiently kill (>5-log-unit decrease) all tested A. baumannii clinical isolates. Treatment with PlyF307 was able to significantly reduce planktonic and biofilm A. baumannii both in vitro and in vivo. Finally, PlyF307 rescued mice from lethal A. baumannii bacteremia and as such represents the first highly active therapeutic lysin specific for Gram-negative organisms in an array of native lysins found in Acinetobacter phage.

Laboratory Maintenance of Acinetobacter baumannii

Acinetobacter baumannii has recently drawn great interest in the microbiology research community due to the increase in clinical antibiotic resistance of this organism, and persistence of this bacterial species in the hospital environment. This unit outlines protocols for the growth and maintenance of A. baumannii in the laboratory.