Successful Treatment of Postneurosurgical Ventriculitis Caused by Extensively Drug-resistant Acinetobacter baumannii in a Child: Case Report

Introduction: The incidence of postneurosurgical Acinetobacter baumannii ventriculitis/meningitis, primarily due to drug-resistant strains, has increased considerably in recent years. However, limited therapeutic options are available because most antibiotics poorly penetrate the blood-brain barrier, especially in pediatric patients. Case Presentation: A five-year-old boy developed ventriculitis due to extensively drug-resistant A. baumannii (XDRAB) after bilateral frontal external ventricular drainage for spontaneous intraventricular hemorrhage. The boy was safely and successfully treated with intraventricular (IVT)/intrathecal (ITH) polymyxin B together with intravenous tigecycline plus cefoperazone/sulbactam. Conclusions: In the present case, postneurosurgical XDRAB ventriculitis was closely associated with intraventricular hemorrhage and the placement of external ventricular drainage. IVT/ITH polymyxin B combined with intravenous tigecycline and cefoperazone sulbactam could be a therapeutic option against XDRAB ventriculitis in children.

Antimicrobial and anti-biofilm potencies of dermcidin-derived peptide DCD-1L against Acinetobacter baumannii: an in vivo wound healing model

Background The global emergence of Acinetobacter baumannii resistance to most conventional antibiotics presents a major therapeutic challenge and necessitates the discovery of new antibacterial agents. The purpose of this study was to investigate in vitro and in vivo anti-biofilm potency of dermcidin-1L (DCD-1L) against extensively drug-resistant (XDR)-, pandrug-resistant (PDR)-, and ATCC19606-A. baumannii. Methods After determination of minimum inhibitory concentration (MIC) of DCD-1L, in vitro anti-adhesive and anti-biofilm activities of DCD-1L were evaluated. Cytotoxicity, hemolytic activity, and the effect of DCD-1L treatment on the expression of various biofilm-associated genes were determined. The inhibitory effect of DCD-1L on biofilm formation in the model of catheter-associated infection, as well as, histopathological examination of the burn wound sites of mice treated with DCD-1L were assessed. Results The bacterial adhesion and biofilm formation in all A. baumannii isolates were inhibited at 2 × , 4 × , and 8 × MIC of DCD-1L, while only 8 × MIC of DCD-1L was able to destroy the pre-formed biofilm in vitro. Also, reduce the expression of genes involved in biofilm formation was observed following DCD-1L treatment. DCD-1L without cytotoxic and hemolytic activities significantly reduced the biofilm formation in the model of catheter-associated infection. In vivo results showed that the count of A. baumannii in infected wounds was significantly decreased and the promotion in wound healing by the acceleration of skin re-epithelialization in mice was observed following treatment with 8 × MIC of DCD-1L. Conclusions Results of this study demonstrated that DCD-1L can inhibit bacterial attachment and biofilm formation and prevent the onset of infection. Taking these properties together, DCD-1L appears as a promising candidate for antimicrobial and anti-biofilm drug development.

MacAB-TolC Contributes to the Development of Acinetobacter baumannii Biofilm at the Solid–Liquid Interface

Acinetobacter baumannii has emerged as one of the most problematic bacterial pathogens responsible for hospital-acquired and community infections worldwide. Besides its high capacity to acquire antibiotic resistance mechanisms, it also presents high adhesion abilities on inert and living surfaces leading to biofilm development. This lifestyle confers additional protection against various treatments and allows it to persist for long periods in various hospital niches. Due to their remarkable antimicrobial tolerance, A. baumannii biofilms are difficult to control and ultimately eradicate. Further insights into the mechanism of biofilm development will help to overcome this challenge and to develop novel antibiofilm strategies. To unravel critical determinants of this sessile lifestyle, the proteomic profiles of two A. baumannii strains (ATTC17978 and SDF) grown in planktonic stationary phase or in mature solid–liquid (S-L) biofilm were compared using a semiquantitative proteomic study. Of interest, among the 69 common proteins determinants accumulated in the two strains at the S-L interface, we sorted out the MacAB-TolC system. This tripartite efflux pump played a role in A. baumannii biofilm formation as demonstrated by using ΔmacAB-tolC deletion mutant. Complementary approaches allowed us to get an overview of the impact of macAB-tolC deletion in A. baumannii physiology. Indeed, this efflux pump appeared to be involved in the envelope stress response occurring in mature biofilm. It contributes to maintain wild type (WT) membrane rigidity and provides tolerance to high osmolarity conditions. In addition, this system is probably involved in the maintenance of iron and sulfur homeostasis. MacAB-TolC might help this pathogen face and adapt to deleterious conditions occurring in mature biofilms. Increasing our knowledge of A. baumannii biofilm formation will undoubtedly help us develop new therapeutic strategies to tackle this emerging threat to human health.

Variants of Tn 6924 , a Novel Tn 7 Family Transposon Carrying the bla NDM Metallo-β-Lactamase and 14 Copies of the aphA6 Amikacin Resistance Genes Found in Acinetobacter baumannii

To date, efforts to study the resistance mechanisms of carbapenem-resistant Acinetobacter baumannii have been largely focused on the two major globally distributed clones (GC1 and GC2). ST85 is an emerging sequence type, and unlike other clones, it is associated with the carriage of the bla NDM gene.

Rescuing Tetracycline Class Antibiotics for the Treatment of Multidrug-Resistant Acinetobacter baumannii Pulmonary Infection

Within intensive care unit settings, multidrug-resistant (MDR) Acinetobacter baumannii is a major cause of ventilator-associated pneumonia, and hospital-associated outbreaks are becoming increasingly widespread. Antibiotic treatment of A. baumannii infection is often compromised by MDR strains resistant to last-resort β-lactam (e.g., carbapenems), polymyxin, and tetracycline class antibiotics.

Complexo Acinetobacter calcoaceticus - Acinetobacter baumannii (ACB): ocorrência e perfil de resistência aos carbapenêmicos e polimixina B durante pandemia de SARS-CoV-2 em Pelotas, RS

Bactérias do complexo Acinetobacter calcoaceticus - Acinetobacter baumannii (ACB) são causa frequente das chamadas Infecções Relacionadas à Assistência à Saúde (IRAS). Durante a pandemia de COVID-19, causada pelo vírus SARS-CoV-2, coinfecções e aumento da resistência bacteriana aos antibióticos têm sido observados. Assim, o presente estudo verificou a ocorrência e perfil de resistência aos carbapenêmicos (no ano de 2020) e a polimixina B (de outubro de 2020 a março de 2021) em bactérias do complexo ACB, durante a pandemia de SARS-CoV-2, no Hospital Escola (HE) da Universidade Federal de Pelotas (UFPel/EBSERH). Duas metodologias foram aplicadas, a de identificação e avaliação da suscetibilidade bacteriana por automação (BD Phoenix™), e avaliação da resistência a polimixina B utilizando painel de microdiluição (CIM POLIMIXINA B, Laborclin). Oitenta e um isolados pertencentes ao complexo ACB foram identificados, sendo 69,1% (56) da espécie A. baumannii e 30,9% (25) de outras espécies do complexo ACB. Foi observado um aumento da resistência aos carbapenêmicos de 75% em 2019, para 94,3% em 2020. Dentre as bactérias do complexo ACB resistentes aos carbapenêmicos, 4 delas foram resistentes também a polimixina B. As bactérias do complexo ACB resistentes aos carbapenêmicos foram mais frequentes na UTI COVID-19, representando 44,9% em relação as outras unidades. Esses isolados resistentes foram obtidos de amostras de aspirado traqueal e sangue. Os dados obtidos revelam um aumento da resistência aos carbapenêmicos, além de uma maior frequência de bactérias do complexo ACB obtidas de aspirado traqueal de pacientes diagnosticados com COVID-19, o que pode estar relacionado a quadros de Pneumonia Associada a Ventilação Mecânica (PAVM).

Treatment, clinical outcomes, and predictors of mortality among a national cohort of admitted patients with Acinetobacter baumannii infection

Objectives: To analyze treatment, clinical outcomes, and predictors of mortality in hospitalized patients with Acinetobacter baumannii infection. Methods: Retrospective cohort study of inpatients with A. baumannii cultures and treatment from 2010-2019. Patients who died during admission were compared to those who survived to identify predictors of inpatient mortality, using multivariable unconditional logistic regression models. Results: We identified 4,599 inpatients with A. baumannii infection; 13.6% died during admission. Fluoroquinolones (26.8%), piperacillin/tazobactam (24%) and carbapenems (15.6%) were used for treatment. Tigecycline (3%) and polymyxins (3.7%) were not used often. Predictors of inpatient mortality included current acute respiratory failure (adjusted odds ratio [aOR] 3.94), shock (aOR 3.05), and acute renal failure (aOR 2.01); blood (aOR 1.94) and respiratory (aOR 1.64) infectious source; multidrug-resistant A. baumannii (MDRAB) infection (aOR 1.66); liver disease (aOR 2.15); and inadequate initial treatment (aOR 1.30). Inpatient mortality was higher in those with MDRAB vs. non-MDRAB (aOR 1.61) and in those with CRAB vs. non-CRAB infection (aOR 1.68). Length of stay >10 days was higher among those with MDRAB vs. non-MDRAB (aOR 1.25) and in those with CRAB vs. non-CRAB infection (aOR 1.31). Conclusions: In our national cohort of inpatients with A. baumannii infection, clinical outcomes were worse among those with MDRAB and/or CRAB infection. Predictors of inpatient mortality included several current conditions associated with severity, infectious source, underlying illness, and inappropriate treatment. Our study may assist healthcare providers in the early identification of admitted patients with A. baumannii infection who are at higher risk of death.

HIỆU QUẢ PHỐI HỢP KHÁNG SINH IN VITRO TRÊN VI KHUẨN GRAM ÂM KHÁNG CARBAPENEM

Đặt vấn đề: Theo Tổ chức Y tế thế giới (WHO), vi khuẩn (VK) Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella pneumoniae kháng carbapenem (APK-CR) là những vi khuẩn (VK) có mức cảnh báo cao nhất, cần ưu tiên phát triển các loại kháng sinh (KS) mới do tình trạng kháng thuốc đáng báo động [7]. Mục tiêu: Khảo sát MIC và hiệu quả phối hợp KS in vitro của meropenem (ME) - colistin (COL) và meropenem - ciprofloxacin (CIP) trên các chủng VK APK-CR. Phương pháp: Nghiên cứu mô tả cắt ngang. Các chủng APK-CR được phân lập tại Bệnh viện Đại học Y Dược TP. HCM từ tháng 12/2020 đến tháng 06/2021. Kết quả: Có 151 chủng gồm 51 chủng A. baumannii, 50 chủng P. aeruginosa và 50 chủng K. pneumoniae. MIC của ME và CIP trên các chủng APK-CR đều cao (chiếm 92-100%); có 6% chủng P. aeruginosa và 10% chủng K. pneumoniae là có MIC kháng COL. Hiệu quả hiệp đồng và cộng hợp trong phối hợp KS in vitro của ME-COL trên APK-CR có tỷ lệ lần lượt là 58,8% và 41,2%, 32% và 60%, 20% và 60%. Hiệu quả hiệp đồng và cộng hợp trong phối hợp KS in vitro của ME-CIP trên APK-CR có tỷ lệ lần lượt là 33,3% và 45,1%, 30% và 60%, 42% và 44%. Kết luận: APK-CR đề kháng với ME, CIP với tỷ lệ rất cao. Phối hợp ME-COL và ME-CIP trên APK-CR có kết quả hiệp đồng và cộng hợp làm giảm tỷ lệ đề kháng KS của APK-CR.