Activities of various β-lactams and β-lactam/β-lactamase inhibitor combinations against Acinetobacter baumannii and Acinetobacter DNA group 3 strains

Supercharged precision killers: Genetically engineered biomimetic drugs of screened metalloantibiotics against Acinetobacter baumanni

To eliminate multidrug-resistant bacteria of Acinetobacter baumannii, we screened 1100 Food and Drug Administration-approved small molecule drugs and accessed the broxyquinoline (Bq) efficacy in combination with various metal ions. Antibacterial tests demonstrated that the prepared Zn(Bq)2 complex showed ultralow minimum inhibitory concentration of ~0.21 micrograms per milliliter with no resistance after 30 passages. We then constructed the nano zeolitic imidazolate framework-8 (ZIF-8) as a drug carrier of Zn(Bq)2 and also incorporated the photosensitizer chlorin e6 (Ce6) to trace and boost the antibacterial effect. To further ensure the stable and targeted delivery, we genetically engineered outer membrane vesicles (OMVs) with the ability to selectively target A. baumannii. By coating the ZnBq/Ce6@ZIF-8 core with these OMV, the resulted drug (ZnBq/Ce6@ZIF-8@OMV) exhibited exceptional killing efficacy (>99.9999999%) of A. baumannii. In addition, in vitro and in vivo tests were also respectively carried out to inspect the remarkable efficacy of this previously unknown nanodrug in eradicating A. baumannii infections, including biofilms and meningitis.

Antibiotic Treatment of Acinetobacter baumannii Superinfection in Patients With SARS-CoV-2 Infection Admitted to Intensive Care Unit: An Observational Retrospective Study

Introduction

In COVID-19 patients on mechanical ventilation, VAP from Acinetobacter baumannii remains a crucial risk factor for death. Antibiotic resistance represents an important problem in treating this infection. This study aims to describe the evolution of the superinfection from PDR Acinetobacter baumannii in patients with acute respiratory failure from SARS-CoV-2 infection admitted to ICU and compare the impact of two different antibiotic strategies on microbiological negativization.

Methods

Single-center observational retrospective study, including patients admitted to our ICU from March 2020 to May 2021 for acute respiratory failure from SARS-CoV-2 infection who developed PDR Acinetobacter baumannii superinfection. Clinical data at ICU admission were collected, as well as the timing of isolation of Acinetobacter baumannii, its resistance profile, the site of infection, and the antibiotic therapy.

Results

Of the 32 patients enrolled, 10 patients (31.2%) were treated with the combination of high-dose ampicillin/sulbactam, high-dose tigecycline, intravenous and inhaled colistin (Protocol), the other 22 (68.8%) were treated with the combination of two antibiotics (Control). Of the 10 patients in the Protocol group, 8 patients (80%) received also fosfomycin. All patients (100%) in the Protocol group had microbiological negativization, while in the Control group microbiological negativization was observed in 8 (36.4%) patients, p < 0.01.

Conclusion

Our report shows microbiological negativization in all patients treated with the combination therapy of nebulized and intravenous colistin, high-dose tigecycline, and high-dose ampicillin/sulbactam. This combination of antibiotics seems to be a useful alternative when other treatments are not available or fail.

Discovery of the Lead Molecules Targeting the First Step of the Histidine Biosynthesis Pathway of Acinetobacter baumannii

Acinetobacter baumannii is a multidrug-resistant, opportunistic, nosocomial pathogen for which a new line of treatments is desperately needed. We have targeted the enzyme of the first step of the histidine biosynthesis pathway, viz., ATP-phosphoribosyltransferase (ATP-PRT). The three-dimensional structure of ATP-PRT was predicted on the template of the known three-dimensional structure of ATP-PRT from Psychrobacter arcticus (PaATPPRT) using a homology modeling approach. High-throughput virtual screening (HTVS) of the antibacterial library of Life Chemicals Inc., Ontario, Canada was carried out followed by molecular dynamics simulations of the top hit compounds. In silico results were then biochemically validated using surface plasmon resonance spectroscopy. We found that two compounds, namely, F0843-0019 and F0608-0626, were binding with micromolar affinities to the ATP-phosphoribosyltransferase from Acinetobacter baumannii (AbATPPRT). Both of these compounds were binding in the same way as AMP in PaATPPRT, and the important residues of the active site, viz., Val4, Ser72, Thr76, Tyr77, Glu95, Lys134, Val136, and Tyr156, were also interacting via hydrogen bonds. The calculated binding energies of these compounds were -10.5 kcal/mol and -11.1 kcal/mol, respectively. These two compounds can be used as the potential lead molecules for designing antibacterial compounds in the future, and this information will help in drug discovery programs against Acinetobacter worldwide.

A novel decoy strategy for polymyxin resistance in Acinetobacter baumannii

Modification of the outer membrane charge by a polymyxin B (PMB)-induced PmrAB two-component system appears to be a dominant phenomenon in PMB-resistant Acinetobacter baumannii. PMB-resistant variants and many clinical isolates also appeared to produce outer membrane vesicles (OMVs). Genomic, transcriptomic, and proteomic analyses revealed that upregulation of the pmr operon and decreased membrane-linkage proteins (OmpA, OmpW, and BamE) are linked to overproduction of OMVs, which also promoted enhanced biofilm formation. The addition of OMVs from PMB-resistant variants into the cultures of PMB-susceptible A. baumannii and the clinical isolates protected these susceptible bacteria from PMB. Taxonomic profiling of in vitro human gut microbiomes under anaerobic conditions demonstrated that OMVs completely protected the microbial community against PMB treatment. A Galleria mellonella-infection model with PMB treatment showed that OMVs increased the mortality rate of larvae by protecting A. baumannii from PMB. Taken together, OMVs released from A. baumannii functioned as decoys against PMB.

Wrapped in a thick, protective outer membrane, Acinetobacter baumannii bacteria can sometimes cause serious infections when they find their way into human lungs and urinary tracts. Antibiotics are increasingly ineffective against this threat, which forces physicians to resort to polymyxin B, an old, positively-charged drug that ‘sticks’ to the negatively-charged proteins and fatty components at the surface of A. baumannii.

Scientists have noticed that when bacteria are exposed to lethal drugs, they often react by releasing vesicles, small ‘sacs’ made of pieces of the outer membranes which can contain DNA or enzymes. How this strategy protects the cells against antibiotics such as polymyxin B remains poorly understood.

To investigate this question, Park et al. examined different strains of A. baumannii, showing that bacteria resistant to polymyxin B had lower levels of outer membrane proteins but would release more vesicles. Adding vesicles from resistant strains to non-resistant A. baumannii cultures helped cells to survive the drugs. In fact, this protective effect extended to other species, shielding whole communities of bacteria against polymyxin B. In vivo, the vesicles protected bacteria in moth larvae infected with A. baumannii, leading to a higher death rate in the animals. Experiments showed that the negatively-charged vesicles worked as decoys, trapping the positively-charged polymyxin B away from its target.

Taken together, the findings by Park et al. highlight a new strategy that allows certain strains of bacteria to protect themselves from antibiotics, while also benefitting the rest of the microbial community.

Phenotypic and WGS-derived antimicrobial resistance profiles of clinical and non-clinical Acinetobacter baumannii isolates from Germany and Vietnam

OBJECTIVES

This study aimed to combine in vitro phenotyping analysis and whole-genome-sequencing (WGS) to characterise the phenotype and genetic determinants associated with intrinsic resistance in 100 clinical and non-clinical Acinetobacter baumannii strains originating from Germany and Vietnam. Moreover, it aimed to assess whether powdered milk as a food source functions as a potential reservoir of antibiotic resistance and possesses similar antimicrobial resistance (AMR) genes as in clinical strains isolated from Germany.

METHODS

Antimicrobial susceptibility testing was performed using the broth microdilution method and the minimum inhibitory concentration (MIC) was determined for 18 antibiotics. The WGS data from all isolates were mapped to intrinsic genes known to be associated with phenotypic AMR.

RESULTS

The highest resistance frequency was observed for chloramphenicol (100%), followed by fosfomycin (96%) and cefotaxime (95%). The lowest resistant rates were observed for colistin (3%), trimethoprim/sulfamethoxazole (17%), tigecycline (19%), and amikacin (19%). Thirty-five percent of tested strains displayed resistance to at least one of the carbapenems. Resistance to fluoroquinolones, aminoglycosides, tigecycline, penicillins, trimethoprim/sulfamethoxazole, and fourth-generation cephalosporins was determined only in human strains. About one-quarter of isolates (24%) was multidrug-resistant (MDR) and all were of human origin. Among them, 16 isolates were extensively drug resistant (XDR) and 10 from those 16 isolates showed resistance to all tested antibiotics except colistin. In silico detection of intrinsic AMR genes revealed the presence of 36 β-lactamases and 24 non-β-lactamase resistance genes. Two colistin-resistant and 10 ertapenem-resistant strains were isolated from powdered milk produced in Germany. Thirty-eight AMR genes associated with resistance to antibiotics were found in isolates recovered from milk powder. Several resistance mechanisms towards many classes of antibiotics existed in A. baumannii including β-lactamases, multidrug efflux pumps and aminoglycoside-modifying enzymes.

CONCLUSION

The use of WGS for routine public health surveillance is a reliable method for the rapid detection of emerging AMR in A. baumannii isolates. Milk powder poses a risk to contain MDR Acinetobacter strains or resistance genes in Germany.

Acinetobacter baumannii Resistance: A Real Challenge for Clinicians

Acinetobacter baumannii (named in honor of the American bacteriologists Paul and Linda Baumann) is a Gram-negative, multidrug-resistant (MDR) pathogen that causes nosocomial infections, especially in intensive care units (ICUs) and immunocompromised patients with central venous catheters. A. baumannii has developed a broad spectrum of antimicrobial resistance, associated with a higher mortality rate among infected patients compared with other non-baumannii species. In terms of clinical impact, resistant strains are associated with increases in both in-hospital length of stay and mortality. A. baumannii can cause a variety of infections; most involve the respiratory tract, especially ventilator-associated pneumonia, but bacteremia and skin wound infections have also been reported, the latter of which has been prominently observed in the context of war-related trauma. Cases of meningitis associated with A. baumannii have been documented. The most common risk factor for the acquisition of MDR A baumannii is previous antibiotic use, following by mechanical ventilation, length of ICU/hospital stay, severity of illness, and use of medical devices. Current efforts focus on addressing all the antimicrobial resistance mechanisms described in A. baumannii, with the objective of identifying the most promising therapeutic scheme. Bacteriophage- and artilysin-based therapeutic approaches have been described as effective, but further research into their clinical use is required.

Spatio-Temporal Distribution of Acinetobacter baumannii in Germany-A Comprehensive Systematic Review of Studies on Resistance Development in Humans (2000-2018)

Acinetobacter (A.) baumannii has gained global notoriety as a significant nosocomial pathogen because it is frequently associated with multi-drug resistance and hospital-based outbreaks. There is a substantial difference in the incidence of A. baumannii infections between different countries and within Germany. However, its continuous spread within Germany is a matter of concern. A systematic literature search and analysis of the literature published between 2000 and 2018 on A. baumannii in humans was performed. Forty-four studies out of 216 articles met the criteria for inclusion, and were selected and reviewed. The number of published articles is increasing over time gradually. Case reports and outbreak investigations are representing the main body of publications. North Rhine-Westphalia, Hesse and Baden-Wuerttemberg were states with frequent reports. Hospitals in Cologne and Frankfurt were often mentioned as specialized institutions. Multiresistant strains carrying diverse resistance genes were isolated in 13 of the 16 German states. The oxacillinase blaOXA-23-like, intrinsic blaOXA-51-like, blaOXA-58 variant, blaNDM-1, blaGES-11, blaCTX-M and blaTEM are the most predominant resistance traits found in German A. baumannii isolates. Five clonal lineages IC-2, IC-7, IC-1, IC-4 and IC-6 and six sequence types ST22, ST53, ST195, ST218, ST944/ST78 and ST348/ST2 have been reported. Due to multidrug resistance, colistin, tigecycline, aminoglycosides, fosfomycin, ceftazidime/avibactam and ceftolozan/tazobactam were often reported to be the only effective antibiotics left to treat quadruple multi-resistant Gram-negative (4MRGN) A. baumannii. Dissemination and infection rates of A. baumannii are on the rise nationwide. Hence, several aspects of resistance development and pathogenesis are not fully understood yet. Increased awareness, extensive study of mechanisms of resistance and development of alternative strategies for treatment are required. One-Health genomic surveillance is needed to understand the dynamics of spread, to identify the main reservoirs and routes of transmission and to develop targeted intervention strategies.

Dual-channel Microchip Electrophoresis with Amperometric Detection System for Rapid Analysis of Cefoperazone and Sulbactam

A dual-channel microchip electrophoresis (ME) with in-channel amperometric detection was developed for cefoperazone and sulbactam determination simultaneously. In this study, a microelectrode detector was made of gold nanoparticles (GNPs) modified indium tin oxide (ITO)-coated poly-ethylene terephthalate (PET) film. The parameters including detection potential applied on working electrode, buffer concentration and pH value were optimized to improve the detection sensitivity and separation efficiency of cefoperazone and sulbactam. Under the optimal conditions, sensitive detection of cefoperazone and sulbactam was obtained with limits of detection (LODs) (S/N = 3) of 0.52 and 0.75 μg/mL, respectively. The plasma sample, which was from a patient with a brain injury taking Sulperazone, was successfully detected with a simple sample pretreatment process by dual-channel ME amperometric detection. This rapid and sensitive method possesses practical potential in clinical applications, and could provide a guidance for clinical rational drug use.

Bacterial etiology of bloodstream infections and antimicrobial resistance in Dhaka, Bangladesh, 2005-2014

Background

Bloodstream infections due to bacterial pathogens are a major cause of morbidity and mortality in Bangladesh and other developing countries. In these countries, most patients are treated empirically based on their clinical symptoms. Therefore, up to date etiological data for major pathogens causing bloodstream infections may play a positive role in better healthcare management. The aim of this study was to identify the bacterial pathogens causing major bloodstream infections in Dhaka, Bangladesh and determine their antibiotic susceptibility pattern.

Methods

From January 2005 to December 2014, a total of 103,679 single bottle blood samples were collected from both hospitalized and domiciliary patients attending Dhaka hospital, icddrb, Bangladesh All the blood samples were processed for culture using a BACT/Alert blood culture machine. Further identification of bacterial pathogens and their antimicrobial susceptibility test were performed using standard microbiological procedures.

Results

Overall, 13.6% of the cultured blood samples were positive and Gram-negative (72.1%) bacteria were predominant throughout the study period. Salmonella Typhi was the most frequently isolated organism (36.9% of samples) in this study and a high percentage of those strains were multidrug-resistant (MDR). However, a decreasing trend in the S. Typhi isolation rate was observed and, noticeably, the percentage of MDR S. Typhi isolated declined sharply over the study period. An overall increase in the presence of Gram-positive bacteria was observed, but most significantly we observed the percentage of MDR Gram-positive bacteria to double over the study period. Overall, Gram positive bacteria were more resistant to most of the commonly used antibiotics than Gram-negative bacteria, but the MDR level was high in both groups.

Conclusions

This study identified the major bacterial pathogens involved with BSI in Dhaka, Bangladesh and also revealed their antibiotic susceptibility patterns. We expect our findings to help healthcare professionals to make informed decisions and provide better care for their patients. Also, we hope this study will assist researchers and policy makers to prioritize their research options to face the future challenges of infectious diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s13756-016-0162-z) contains supplementary material, which is available to authorized users.

Sulbactam treatment for pneumonia involving multidrug-resistant Acinetobacter calcoaceticus-Acinetobacter baumannii complex

BACKGROUND

Multidrug-resistant (MDR) Acinetobacter calcoaceticus-Acinetobacter baumannii (Acb) complex has become an important cause of nosocomial pneumonia. Sulbactam is a β-lactamase inhibitor with antimicrobial activity against MDR Acb complex.

METHODS

To investigate outcomes of pneumonia involving MDR Acb complex treated with sulbactam or ampicillin/sulbactam for at least 7 days, we conducted a retrospective study of 173 adult patients over a 34 month period.

RESULTS

Of 173 patients, 138 (79.8%) received combination therapy, mainly with carbapenems (119/138, 86.2%). The clinical response rate was 67.6% and the 30 day mortality rate was 31.2%. The independent predictors of clinical failure were malignancy, bilateral pneumonia and shorter duration of treatment. In patients with sulbactam-susceptible strains, there was no difference in clinical and microbiological outcome between combination therapy and monotherapy. Compared to the sulbactam-susceptible group, the sulbactam-resistant group had a lower rate of airway eradication, a longer duration of treatment and a higher rate of combination therapy with predominantly carbapenems (p < 0.05). There was no significant difference between the two groups in clinical resolution and 30 day mortality rates.

CONCLUSIONS

Sulbactam could be a treatment option for pneumonia involving MDR Acb complex, and combination therapy with carbapenems could be considered for sulbactam-resistant cases.

Tracing the emergence of multidrug-resistant Acinetobacter baumannii in a Taiwanese hospital by evaluating the presence of integron gene intI1

Background

In Changhua County, Taiwan, the number of clinical Acinetobacter baumannii isolates has risen since 2002, and multidrug-resistant Acinetobacter baumannii (MDRAB) has spread rapidly throughout Taiwan. In this study, to reveal the mechanism involved with the rapid dissemination of MDRAB emergence, the utility of the class 1 integron, intI1 integrase gene, as an MDRAB-associated biomarker was examined. A cross-sectional, clinical epidemiological study was performed at Changhua Christian Hospital between January 1^st, 2001 and December 31^st, 2004. Besides the existence of intI1 gene was examined, the pulse-field gel electrophoresis (PFGE) was also performed to determine the epidemiological characteristics of the isolates.

Findings

The overall hospital infection rate was 5–6%, while the infection rate of the intensive care unit (ICU) fluctuated. No positive correlation was observed between MDRAB isolates and the presence of intI1 (r = 0.168, P = 0.254). Additionally, no positive correlation was observed between the infection rate in the ICU and the presence of intI1 (r = -0.107, P = 0.468) or between the hospital infection rate and the presence of intI1 (r = -0.189, P = 0.199). However, two predominant clones among the MDRAB isolates were identified by PFGE.

Conclusions

Although the presence of the intI1 gene does not seem suitable for tracing MDRAB emergence in Changhua County, two predominant clones were identified by PFGE, and subsequent studies to identify whether these clones were responsible for original nosocomial infection are needed.

The minimal inhibitory concentration for sulbactam was not associated with the outcome of infections caused by carbapenem-resistant Acinetobacter sp. treated with ampicillin/sulbactam

OBJECTIVE

The objective of this study was to evaluate whether the outcomes of carbapenem-resistant Acinetobacter infections treated with ampicillin/sulbactam were associated with the in vitro susceptibility profiles.

METHODS

Twenty-two infections were treated with ampicillin/sulbactam. The median treatment duration was 14 days (range: 3-19 days), and the median daily dose was 9 g (range: 1.5-12 g). The median time between Acinetobacter isolation and treatment was 4 days (range: 0-11 days).

RESULTS

The sulbactam minimal inhibitory concentration (MIC) ranged from 2.0 to 32.0 mg/L, and the MIC was not associated with patient outcome, as 4 of 5 (80%) patients with a resistant infection (MIC≥16), 5 of 10 (50%) patients with intermediate isolates (MIC of 8) and only 1 of 7 (14%) patients with susceptible isolates (MIC ≤4) survived hospitalization.

CONCLUSION

These findings highlight the need to improve the correlation between in vitro susceptibility tests and clinical outcome.

A European survey of professional bodies representing occupational medicine specialists

BACKGROUND

Professional societies and associations of occupational medicine (OM) play a key role in the development and cohesion of the speciality including its interaction with other disciplines.

AIMS

To understand the way the speciality operates across Europe, a survey of the current European professional bodies of OM specialists was conducted on behalf of the European Union of Medical Specialists (UEMS) section of OM.

METHODS

A cross-sectional survey was conducted asking country delegates of the UEMS section of OM to complete a questionnaire exploring the characteristics and activities of their professional associations/societies.

RESULTS

Twenty-four countries in total were contacted, with a response rate of 92%. In all, 78% of organizations were open to non-occupational physicians, nurses or other occupational health professionals; all except two had a fee under €200 per year, and 65% provided services with no dedicated administrative support. All organizations provided educational events, in addition to other services including website support, production of position documents, practice guidelines and quality assurance of professional practice.

CONCLUSIONS

The European associations of OM specialists deliver a wide range of services and educational activities despite limited resources. Further research is needed to explore the potential strategic and political effects associated with differing membership models, assess the nature and standard of medical education provided by the different organizations, and identify areas for collaboration within Europe. Future actions within OM associations would support the development of the speciality within Europe.

Emergence of resistance to carbapenems in Acinetobacter baumannii in Europe: clinical impact and therapeutic options

Despite having a reputation of low virulence, Acinetobacter baumannii is an emerging multidrug-resistant (MDR) pathogen responsible for community- and hospital-acquired infections that are difficult to control and treat. Interest in this pathogen emerged about one decade ago because of its natural MDR phenotype, its capability of acquiring new mechanisms of resistance and the existence of nosocomial outbreaks. Recent advances in molecular biology, including full genome sequencing of several A. baumannii isolates, has led to the discovery of the extraordinary plasticity of their genomes, which is linked to their great propensity to adapt to any environment, including hospitals. In this context, as well as the increasing antimicrobial resistance amongst A. baumannii isolates to the last-line antibiotics carbapenems and colistin, therapeutic options are very limited or absent in some cases of infections with pandrug-resistant bacteria. However, a large proportion of patients may be colonised by such MDR bacteria without any sign of infection, leading to a recurrent question for clinicians as to whether antibiotic treatment should be given and will be effective in the presence of resistance mechanisms. The worldwide emergence of A. baumannii strains resistant to colistin is worrying and the increasing use of colistin to treat infections caused by MDR bacteria will inevitably increase the recovery rate of colistin-resistant isolates in the future. Current knowledge about A. baumannii, including biological and epidemiological aspects as well as resistance to antibiotics and antibiotic therapy, are reviewed in this article, in addition to therapeutic recommendations.

Multidrug resistant acinetobacter

Emergence and spread of Acinetobacter species, resistant to most of the available antimicrobial agents, is an area of great concern. It is now being frequently associated with healthcare associated infections. Literature was searched at PUBMED, Google Scholar, and Cochrane Library, using the terms ‘Acinetobacter Resistance, multidrug resistant (MDR), Antimicrobial Therapy, Outbreak, Colistin, Tigecycline, AmpC enzymes, and carbapenemases in various combinations. The terms such as MDR, Extensively Drug Resistant (XDR), and Pan Drug Resistant (PDR) have been used in published literature with varied definitions, leading to confusion in the correlation of data from various studies. In this review various mechanisms of resistance in the Acinetobacter species have been discussed. The review also probes upon the current therapeutic options, including combination therapies available to treat infections due to resistant Acinetobacter species in adults as well as children. There is an urgent need to enforce infection control measures and antimicrobial stewardship programs to prevent the further spread of these resistant Acinetobacter species and to delay the emergence of increased resistance in the bacteria.

Executive Summary: Clinical Practice Guideline for the Use of Antimicrobial Agents in Neutropenic Patients with Cancer: 2010 Update by the Infectious Diseases Society of America

This document updates and expands the initial Infectious Diseases Society of America (IDSA) Fever and Neutropenia Guideline that was published in 1997 and first updated in 2002. It is intended as a guide for the use of antimicrobial agents in managing patients with cancer who experience chemotherapy-induced fever and neutropenia.

Recent advances in antimicrobial drug development and technology, clinical trial results, and extensive clinical experience have informed the approaches and recommendations herein. Because the previous iteration of this guideline in 2002, we have a developed a clearer definition of which populations of patients with cancer may benefit most from antibiotic, antifungal, and antiviral prophylaxis. Furthermore, categorizing neutropenic patients as being at high risk or low risk for infection according to presenting signs and symptoms, underlying cancer, type of therapy, and medical comorbidities has become essential to the treatment algorithm. Risk stratification is a recommended starting point for managing patients with fever and neutropenia. In addition, earlier detection of invasive fungal infections has led to debate regarding optimal use of empirical or preemptive antifungal therapy, although algorithms are still evolving.

What has not changed is the indication for immediate empirical antibiotic therapy. It remains true that all patients who present with fever and neutropenia should be treated swiftly and broadly with antibiotics to treat both gram-positive and gram-negative pathogens.

Finally, we note that all Panel members are from institutions in the United States or Canada; thus, these guidelines were developed in the context of North American practices. Some recommendations may not be as applicable outside of North America, in areas where differences in available antibiotics, in the predominant pathogens, and/or in health care–associated economic conditions exist. Regardless of venue, clinical vigilance and immediate treatment are the universal keys to managing neutropenic patients with fever and/or infection.

Septic arthritis of the knee caused by antibiotic-resistant Acinetobacter baumannii in a gout patient: a rare case report

Over recent years, the incidence of infection caused by antibiotic-resistant Acinetobacter baumannii (a conditional pathogenic bacterium) has showed an increasing trend in such hospital departments as ICUs. Infections caused by antibiotic-resistant A. baumannii have drawn much attention from the medical professionals because it is difficult to manage such infections, and because the mortality related to such infections is high. To date, no cure of gouty arthritis and septic arthritis meanwhile complicated by antibiotic-resistant A. baumannii infection has been reported. We cured such a patient of intractable knee infection caused by A. baumannii resistant to all conventional antibiotics including imipenem by taking comprehensive measures including surgery, and infection did not recur during the 14-month follow-up.

Drug treatment for multidrug-resistant Acinetobacter baumannii infections

Acinetobacter baumannii has emerged in the last decades as a major cause of healthcare-associated infections and nosocomial outbreaks. Multidrug-resistant (MDR) A. baumannii is a rapidly emerging pathogen in healthcare settings, where it causes infections that include bacteremia, pneumonia, meningitis, and urinary tract and wound infections. Antimicrobial resistance poses great limits for therapeutic options in infected patients, especially if the isolates are resistant to the carbapenems. Other therapeutic options include sulbactam, aminoglycosides, polymixyns and tigecycline. The discovery of new therapies coupled with the development of controlled clinical trial antibiotic testing combinations and the prevention of transmission of MDR Acinetobacter infection are essential to face this important hospital problem.

Acinetobacter baumannii: epidemiology, antimicrobial resistance, and treatment options

Multidrug-resistant Acinetobacter baumannii is recognized to be among the most difficult antimicrobial-resistant gram-negative bacilli to control and treat. Increasing antimicrobial resistance among Acinetobacter isolates has been documented, although definitions of multidrug resistance vary in the literature. A. baumannii survives for prolonged periods under a wide range of environmental conditions. The organism causes outbreaks of infection and health care-associated infections, including bacteremia, pneumonia, meningitis, urinary tract infection, and wound infection. Antimicrobial resistance greatly limits the therapeutic options for patients who are infected with this organism, especially if isolates are resistant to the carbapenem class of antimicrobial agents. Because therapeutic options are limited for multidrug-resistant Acinetobacter infection, the development or discovery of new therapies, well-controlled clinical trials of existing antimicrobial regimens and combinations, and greater emphasis on the prevention of health care-associated transmission of multidrug-resistant Acinetobacter infection are essential.

Sulbactam-containing beta-lactamase inhibitor combinations

Sulbactam irreversibly inhibits the hydrolytic activity of beta-lactamases. This compound is commercially available in combination with either ampicillin or cefoperazone. In each instance, the activity of the partner antibiotic against beta-lactamase-producing bacteria is restored. One of the particular advantages of using sulbactam-containing combinations is that sulbactam itself has inherent activity against some Acinetobacter baumannii. Sulbactam combinations have not demonstrated strong selective pressures for extended-spectrum beta-lactamase-producing Enterobacteriaceae and vancomycin-resistant enterococci. In contrast to clavulanate, sulbactam does not induce class I (Ampc) chromosomal beta-lactamases in Enterobacteriaceae.

Neumonía nosocomial por Acinetobacter baumannii

Acinetobacter baumannii is a significant cause of nosocomial pneumonia, especially late ventilator-associated pneumonia. In Spain, A. baumannii is the third leading pathogen after Pseudomonas aeruginosa and Staphylococcus aureus. Risk factors for pneumonia due to A. baumannii are head injury, neurosurgery, acute respiratory distress syndrome, aspiration, and previous antibiotic therapy. Definitive diagnosis requires respiratory samples and invasive techniques with quantitative cultures to differentiate true infections from simple colonizations. The crude mortality of patients with ventilator-associated A. baumannii pneumonia is high, although the attributable mortality is controversial. Adequate empirical antimicrobial therapy of A. baumannii pneumonia is a protective factor, even though the therapeutic options are often limited. The treatment of choice is imipenem and sulbactam may be considered an acceptable alternative. Nowadays, colistin is the treatment of choice in A. baumannii pneumonia caused by panresistant strains. The associations of imipenem and rifampin or imipenem and sulbactam may be acceptable alternatives to colistin in infections caused by these strains. Surveillance measures are essential to eradicate this multidrug-resistant pathogen in outbreaks and reduce the number of episodes in endemic situations. Although these measures are important throughout the hospital, intensive care units are especially high-risk areas.