Therapeutic evaluation of the Acinetobacter baumannii phage Phab24 for clinical use

Phages have shown to be effective in treating bacterial infections. However, when evaluating the therapeutic potential of novel phage isolates which have the ability to infect and kill a pathogen, it is important to include parameters such as stability (crucial for storage and delivery), infection dynamics in vitro and in vivo (for efficacy and dosing), and an in-depth genome analysis (to exclude the presence of virulence or lysogeny genes), among others. In this study, we characterized bacteriophage Phab24, which infects a colistin-resistant strain of the notorious nosocomial pathogen Acinetobacter baumannii. Our study is crucial for the use of Phab24 in therapy, while also advancing our understanding of phage predation.

Bacteriophage therapeutics to confront multidrug-resistant Acinetobacter baumannii - a global health menace

We have already entered the post-antibiotic era as the outbreaks of numerous multidrug-resistant strains in the community as well as hospital-acquired infections are ringing alarm bells in the health sector. Acinetobacter baumannii is one such pathogen that has been considered a worldwide threat as it acquires multidrug resistance. It is one of the most challenging hospital-acquired pathogens as World Health Organization has listed carbapenem-resistant A. baumannii as a critical priority pathogen with limited therapeutic options. There is an urgent need to develop novel strategies against such pathogens to tackle the global crisis. Bacteriophages (phages), especially the lytic ones have re-emerged as a potential therapeutic approach. This review encompasses vast majority of phages against A. baumannii strains with special references related to single phage or monophage therapy, use of phage cocktails, combination therapy with antibiotics, use of phage-derived enzymes like endolysins and depolymerases to combat the pathogen and explore their therapeutic aspects. The concurrent ecological as well as evolutionary interplay between the phages and host bacteria demands in depth-research and knowledge, so as to utilize the maximum potential of the bacteriophage therapy.

Preclinical Assessment of Bacteriophage Therapy against Experimental Acinetobacter baumannii Lung Infection

Respiratory infections caused by multidrug-resistant Acinetobacter baumannii are difficult to treat and associated with high mortality among critically ill hospitalized patients. Bacteriophages (phages) eliminate pathogens with high host specificity and efficacy. However, the lack of appropriate preclinical experimental models hampers the progress of clinical development of phages as therapeutic agents. Therefore, we tested the efficacy of a purified lytic phage, vB_AbaM_Acibel004, against multidrug-resistant A. baumannii clinical isolate RUH 2037 infection in immunocompetent mice and a human lung tissue model. Sham- and A. baumannii-infected mice received a single-dose of phage or buffer via intratracheal aerosolization. Group-specific differences in bacterial burden, immune and clinical responses were compared. Phage-treated mice not only recovered faster from infection-associated hypothermia but also had lower pulmonary bacterial burden, lower lung permeability, and cytokine release. Histopathological examination revealed less inflammation with unaffected inflammatory cellular recruitment. No phage-specific adverse events were noted. Additionally, the bactericidal effect of the purified phage on A. baumannii was confirmed after single-dose treatment in an ex vivo human lung infection model. Taken together, our data suggest that the investigated phage has significant potential to treat multidrug-resistant A. baumannii infections and further support the development of appropriate methods for preclinical evaluation of antibacterial efficacy of phages.

Monoclonal IgM Antibodies Targeting Candida albicans Hyr1 Provide Cross-Kingdom Protection Against Gram-Negative Bacteria

Recent years have seen an unprecedented rise in the incidence of multidrug-resistant (MDR) Gram-negative bacteria (GNBs) such as Acinetobacter and Klebsiella species. In view of the shortage of novel drugs in the pipeline, alternative strategies to prevent, and treat infections by GNBs are urgently needed. Previously, we have reported that the Candida albicans hypha-regulated protein Hyr1 shares striking three-dimensional structural homology with cell surface proteins of Acinetobacter baumannii. Moreover, active vaccination with rHyr1p-N or passive immunization with anti-Hyr1p polyclonal antibody protects mice from Acinetobacter infection. In the present study, we use molecular modeling to guide design of monoclonal antibodies (mAbs) generated against Hyr1p and show them to bind to priority surface antigens of Acinetobacter and Klebsiella pneumoniae. The anti-Hyr1 mAbs block damage to primary endothelial cells induced by the bacteria and protect mice from lethal pulmonary infections mediated by A. baumannii or K. pneumoniae. Our current studies emphasize the potential of harnessing Hyr1p mAbs as a cross-kingdom immunotherapeutic strategy against MDR GNBs.

Bloodstream infections caused by carbapenem-resistant Acinetobacter baumannii: Clinical features, therapy and outcome from a multicenter study

OBJECTIVES

bloodstream infections (BSI) due to multidrug-resistant (MDR) Acinetobacter baumannii (AB) have been increasingly observed among hospitalized patients.

METHODS

prospective, observational study conducted among 12 large tertiary-care hospitals, across 7 Italian regions. From June 2017 to June 2018 all consecutive hospitalized patients with bacteremia due to MDR-AB were included and analyzed in the study.

RESULTS

During the study period 281 episodes of BSI due to MDR-AB were observed: 98 (34.8%) episodes were classified as primary bacteremias, and 183 (65.2%) as secondary bacteremias; 177 (62.9%) of them were associated with septic shock. Overall, 14-day mortality was observed in 172 (61.2%) patients, while 30-day mortality in 207 (73.6%) patients. On multivariate analysis, previous surgery, continuous renal replacement therapy, inadequate source control of infection, and pneumonia were independently associated with higher risk of septic shock. Instead, septic shock and Charlson Comorbidity Index >3 were associated with 14-day mortality, while adequate source control of infection and combination therapy with survival. Finally, septic shock, previous surgery, and aminoglycoside-containing regimen were associated with 30-day mortality, while colistin-containing regimen with survival.

CONCLUSIONS

BSI caused by MDR-AB represents a difficult challenge for physicians, considering the high rates of septic shock and mortality associated with this infection.

Analysis of colony phase variation switch in Acinetobacter baumannii clinical isolates

Reversible switching between opaque and translucent colony formation is a novel feature of Acinetobacter baumannii that has been associated with variations in the cell morphology, surface motility, biofilm formation, antibiotic resistance and virulence. Here, we assessed a number of phenotypic alterations related to colony switching in A. baumannii clinical isolates belonging to different multi-locus sequence types. Our findings demonstrated that these phenotypic alterations were mostly strain-specific. In general, the translucent subpopulations of A. baumannii produced more dense biofilms, were more piliated, and released larger amounts of outer membrane vesicles (OMVs). In addition, the translucent subpopulations caused reduced fertility of Caenorhabditis elegans. When assessed for effects on the immune response in RAW 264.7 macrophages, the OMVs isolated from opaque subpopulations of A. baumannii appeared to be more immunogenic than the OMVs from the translucent form. However, also the OMVs from the translucent subpopulations had the potential to evoke an immune response. Therefore, we suggest that OMVs may be considered for development of new immunotherapeutic treatments against A. baumannii infections.

Natural prognosis of carbapenem-resistant Acinetobacter baumannii bacteremia in patients who did not receive appropriate antibiotic treatment: A retrospective multicenter study in Korea

Carbapenem-resistant Acinetobacter baumannii (CRAB) infection is a major issues in current era. The aim of study was to investigate the natural prognosis and prognostic factors associated with 28-day mortality in patients with CRAB bacteremia who were not receiving appropriate antibiotic treatment.Adult patients with CRAB bacteremia were retrospectively identified between April 2012 and March 2015 at 5 tertiary hospitals in Republic of Korea. Patients who were transferred to another hospital within 28 days of onset of bacteremia and who receive appropriate antibiotics more than 48 hours were excluded. We investigated prognostic factors associated with 28-day mortality in patients with CRAB bacteremia without appropriate antibiotic treatment.Of enrolled 205 patients, 143 (69.8%) patients died within 28 days after blood culture. Of patients with 28-day mortality, 88.9% (127/143) of patients died within 5 days. Of 78 patients who survived more than 5 days, the 28-day mortality was 20.5% (16/78). Diabetes mellitus (adjusted odds ratio [aOR] 3.81, 95% confidence interval [95% CI] 1.19-12.20), immunocompromised (aOR 8.72, 95% CI 2.62-29.70), sequential organ failure assessment (SOFA) ≥ 10 (aOR 13.87, 95% CI 3.70-51.96), vasopressor use (aOR 7.03, 95% CI 1.79-27.60), and pneumonia (aOR 4.44, 95% CI 1.67-11.78) were found to be the factors independently associated with the 28-day mortality.The 28-day mortality in patients with CRAB bacteremia without appropriate treatment was high, although some patients could survive. Severity and underlying conditions were important prognostic factors in patients with CRAB bacteremia.

The Capsular Polysaccharide of Acinetobacter baumannii Is an Obstacle for Therapeutic Passive Immunization Strategies

Acinetobacter baumannii has become an important concern for human health due to rapid development and wide spread of antimicrobial-resistant strains and high mortality associated with the infection. Passive immunizations with antisera targeting outer membrane proteins (OMPs) have shown encouraging results in protecting mice from A. baumannii infection, but monoclonal anti-OMP antibodies have not been developed, and their potential therapeutic properties have not been explored. The goal of this report is to evaluate the antibacterial activity of monoclonal antibodies (MAbs) targeting outer membrane protein A (OmpA) of A. baumannii Five anti-OmpA MAbs were developed using hybridoma technology and showed strong binding to strain ATCC 19606. However, low antibody binding was observed when they were tested against six clinical isolates, which included extensively drug-resistant strains. In contrast, high binding to an isogenic K1 capsule-negative mutant (AB307.30) was shown, suggesting that capsular polysaccharide mediated the inhibition of MAb binding to OmpA. Anti-OmpA MAbs increased the macrophage-mediated bactericidal activity of AB307.30 but failed to increase phagocytic killing of capsule-positive strains. Capsular polysaccharide was also protective against complement-mediated bactericidal activity in human ascites in the presence and absence of opsonization. Lastly, passive immunization with anti-OmpA MAbs did not confer protection against challenge with AB307-0294, the encapsulated parent strain of AB307.30, in a mouse sepsis infection model. These results reveal the important role of capsule polysaccharide in shielding OmpA and thereby inhibiting anti-OmpA MAb binding to clinical isolates. This property of capsule hindered the therapeutic utility of anti-OmpA MAbs, and it may apply to other conserved epitopes in A. baumannii.

The role of surgery in necrotizing otitis externa

This retrospective case review describes a subset of 5 patients with necrotizing otitis externa (NOE) with a refractory disease course who underwent surgery as part of their management plan between 2008 and 2013. Surgery promoted the cure of 4 of the 5 patients, and a fungal pathogen was recovered in 4 of 5 surgical samples. We conclude that surgery may be a necessary diagnostic and treatment adjunct in selective cases of NOE, especially in patients with a refractory disease course or with a suspected fungal etiology.

The Role of Endoscopic Lavage in Recalcitrant Multidrug-Resistant Gram-Negative Ventriculitis Among Neurosurgical Patients

INTRODUCTION

Ventriculitis is a serious infection associated with high mortality even when both intravenous (IV) and intrathecal (IT) antibiotics are administered. Poor outcome in patients with ventriculitis indicates the need to be more aggressive in our attempts to expeditiously eradicate the infection. The purpose of this study was to evaluate the role of endoscopic lavage (EL) in patients with severe purulent ventriculitis, unresponsive to IV and IT antibiotics.

METHODS

All consecutive patients with severe ventriculitis caused by multidrug-resistant gram-negative bacteria, undergoing EL after failure of prolonged courses of IV and IT antibiotics, were included in the study. The outcome in all these patients was otherwise expected to be uniformly dismal.

RESULTS

There were 5 males and 2 females. The age range was one month to 45 years. All patients had frank intraventricular pus. Acinetobacter baumannii was the most common organism grown in cultures. Two patients had multiple bacterial growth in cerebrospinal fluid cultures. The duration of pre-EL IV/IT antibiotics ranged from 3 to 8 weeks. Microbiological cure was achieved in all (7/7) and clinical cure in 86% of patients (6/7). One patient died despite achieving cerebrospinal fluid sterilization 3 months later as a result of progressive white matter edema.

CONCLUSIONS

The addition of IT antibiotics has resulted in improved outcome in patients with ventriculitis; however, some patients continue to be unresponsive to antibiotics. EL can play a complementary role in eradicating such recalcitrant infections. EL should be considered in any patient with ventriculitis, if infection persists even after ∼7-10 days of IVand IT antibiotics.

Clinical manifestations of pneumonia according to the causative organism in patients in the intensive care unit

BACKGROUND/AIMS

Whether the causative organism influences the clinical course of pneumonia in the intensive care unit (ICU) is controversial. We assessed the clinical manifestations and prognosis of pneumonia according to the causative pathogens in patients in a medical ICU.

METHODS

A retrospective observational study was performed in a medical ICU. Among 242 patients who were admitted to the ICU, 103 who were treated for pneumonia were analyzed.

RESULTS

The causative pathogen was identified in 50 patients (49.0%); 22 patients (21.6%) had multidrug-resistant (MDR) pathogens. The distribution of causative micro-organisms was Staphylococcus aureus (20%), Pseudomonas species (16%), Klebsiella pneumoniae (14%), and Acinetobacter baumannii (12%). No significant difference in ICU mortality rate, duration of ICU stay, duration of mechanical ventilation, or frequencies of re-intubation and tracheostomy were detected based on the identification of any pathogen. In sub-analyses according to the pneumonia classification, the number of pathogens identified did not differ between pneumonia types, and a higher incidence of identified MDR pathogens was detected in the hospital-acquired pneumonia group than in the community-acquired or healthcare- acquired pneumonia groups. However, the clinical outcomes of pneumonia according to identification status and type of pathogen did not differ significantly between the groups.

CONCLUSIONS

Neither the causative micro-organism nor the existence of MDR pathogens in critically ill patients with pneumonia was associated with the clinical outcome of pneumonia, including ICU mortality. This result was consistent regardless of the pneumonia classification.

SUCCESSFUL TREATMENT OF MULTIDRUG-RESISTANT ACINETOBACTOR BAUMANII BLISTERS ON THE KNEE

Acinetobacter baumannii (A. baumannii), nosocomial infections, especially those due to multi-drug resistant (MDR) strains, are increasingly detected. This study reports the case of a 50-year-old man with blisters on the right knee for 8 months, first admitted through the outpatient department for incisional biopsy. Microbiological and histo-pathological examination confirmed the diagnosis of blisters extending deeply up to the knee joint caused by MDR- A. baumannii. A broad spectrum antibiotic therapy was administered and later readjusted according to the results of microbiological culture and biopsy report. Intensive hemodynamic support was required. An extensive surgical debridement was promptly performed and repeated until complete control of the infection with intravenous colistins. Blisters were excised; wounds were dressed daily with chlorhexidine dressings and polymyxine-impregnated dressing. Wounds were finally covered with split-thickness skin grafts. The infection was overcome 120 days after admission. The graft take was 40%. Postoperative rehabilitation was required because of the functional limitation of lower limb movements at the knee joint. Follow-up at 8 months showed no functional deficit and an acceptable aesthetic result. AB-MDR affecting soft tissues is a life-threatening disease, especially in patients with poor immunity and limited access to health facilities, whose clinical diagnosis may sometimes be challenging. Early recognition and treatment represent the most important factors influencing survival.

Optimized polymeric film-based nitric oxide delivery inhibits bacterial growth in a mouse burn wound model

Nitric oxide (NO) has many biological roles (e.g. antimicrobial agent, promoter of angiogenesis, prevention of platelet activation) that make NO releasing materials desirable for a variety of biomedical applications. Localized NO release can be achieved from biomedical grade polymers doped with diazeniumdiolated dibutylhexanediamine (DBHD/N2O2) and poly(lactic-co-glycolic acid) (PLGA). In this study, the optimization of this chemistry to create film/patches that can be used to decrease microbial infection at wound sites is examined. Two polyurethanes with different water uptakes (Tecoflex SG-80A (6.2±0.7wt.%) and Tecophilic SP-60D-20 (22.5±1.1wt.%)) were doped with 25wt.% DBHD/N2O2 and 10wt.% of PLGA with various hydrolysis rates. Films prepared with the polymer that has the higher water uptake (SP-60D-20) were found to have higher NO release and for a longer duration than the polyurethane with the lower water uptake (SG-80A). The more hydrophilic polymer enhances the hydrolysis rate of the PLGA additive, thereby providing a more acidic environment that increases the rate of NO release from the NO donor. The optimal NO releasing and control SG-80A patches were then applied to scald burn wounds that were infected with Acinetobacter baumannii. The NO released from these patches applied to the wounds is shown to significantly reduce the A. baumannii infection after 24h (∼4 log reduction). The NO release patches are also able to reduce the level of transforming growth factor-β in comparison to controls, which can enhance re-epithelialization, decrease scarring and reduce migration of bacteria. The combined DBHD/N2O2 and PLGA-doped polymer patches, which could be replaced periodically throughout the wound healing process, demonstrate the potential to reduce risk of bacterial infection and promote the overall wound healing process.

[Lower respiratory tract infections related to Stenotrophomonas maltophilia and Acinetobacter baumannii]

Stenotrophomonas maltophilia and Acinetobacter baumannii are both non-fermenting ubiquitous Gram-negative bacilli. The incidence of lower respiratory tract infections related to these microorganisms is increasing, especially in intensive care units. Their capacity to acquire resistance against several antimicrobials is challenging for clinicians and microbiologists. Despite their low virulence, these pathogens are responsible for colonization and infection in patients with comorbidities, immunosuppression, and critically ill patients. S. maltophilia and A. baumannii are mainly identified in nosocomial infections: ventilator-associated pneumonia, bacteremia and surgical wound infection. Infections related to these microorganism are associated with high mortality and morbidity. Trimethoprime-sulfamethoxazole and carbapenem are the first line treatment for infections related to S. maltophilia and A. baumannii respectively. However, the increasing rate of resistance against these agents results in difficulties in treating patients with infections related to these pathogens. New antimicrobial agents and further randomized studies are needed to improve the treatment of these infections. Prevention of spared of these multidrug-resistant bacteria is mandatory, including hand-hygiene, environment cleaning, and limited usage of large spectrum antibiotics.

A case of fulminant community-acquired Acinetobacter baumannii pneumonia in Korea

Acinetobacter baumannii (AB) is a common pathogen found in patients with hospital-acquired pneumonia all over the world. Community-acquired AB pneumonia, however, is very rare and has seldom been reported in Asia-Pacific countries. Community-acquired AB pneumonia has a fulminant course and is associated with a higher mortality than hospital-acquired AB pneumonia. In Korea, no case of fatal community-acquired AB pneumonia has been reported to date. Here, we describe the first fatal case of fulminant community-acquired AB pneumonia in Korea.

[CSF otorrhea: case report and management]

Mr G, sixty-seven years old, was admitted to our hospital for a liver transplant. He suffered from a cirrhosis due to an HBV infection, complicated by an hepatocellular carcinoma. During the perioperative care, a left otorrhea was discovered. According to the clinical history, this otorrhea had been present for six weeks and followed the completion of a myringotomy. The myringotomy had been performed with a view to place a transtympanic ventilation tube for the treatment of a serous otitis media inducing a conductive hearingloss. Clinical, biological, and radiological explorations revealed a CSF leak caused by the fact that the myringotomy had been done in a temporal meningo-encephalocele. A conservative treatment allowed to stop the otorrhea. We present a short discussion about temporal meningoencephalocele and, more generally, about CSF otorrhea.

Isolation and characterization of φkm18p, a novel lytic phage with therapeutic potential against extensively drug resistant Acinetobacter baumannii

AIMS

To isolate phages against extensively drug resistant Acinetobacter baumannii (XDRAB) and characterize the highest lytic capability phage as a model to evaluate the potential on phage therapy.

METHODS AND RESULTS

Eight phages were isolated from hospital sewage and showed narrow host spectrum. Phage φkm18p was able to effectively lyse the most XDRAB. It has a dsDNA genome of 45 kb in size and hexagonal head of about 59 nm in diameter and no tail. Bacterial population decreased quickly from 10(8) CFU ml(-1) to 10(3) CFU ml(-1) in 30 min by φkm18p. The 185 kDa lysis protein encoded by φkm18p genome was detected when the extracted protein did not boil before SDS-PAGE; it showed that the lysis protein is a complex rather than a monomer. Phage φkm18p improved human lung epithelial cells survival rates when they were incubated with A. baumannii. Combination of phages (φkm18p, φTZ1 and φ314) as a cocktail could lyse all genotype-varying XDRAB isolates.

CONCLUSION

Infections with XDRAB are extremely difficult to treat and development of a phage cocktails therapy could be a therapeutic alternative in the future. Phage φkm18p is a good candidate for inclusion in phage cocktails.

Multidrug-resistant Acinetobacter baumannii infection following para-articular steroid injection in the knee--a case report

Acinetobacter baumannii is an emerging gram-negative nosocomial pathogen that rarely causes infections in orthopaedic patients. We report a case of imipenem-resistant Acinetobacter baumannii paraarticular infection of the knee occurring in a healthy patient following one ambulatory steroid injection for the treatment of quadriceps tendinopathy. The infection was reduced by early surgical debridement of infected tissues, abscess drainage, and prolonged antibiotic therapy with colistin. To our knowledge, this is the first case in the literature reporting such an infection following single steroid injection in orthopaedic patients.

[Acinetobacter baumannii bacteremia]

Acinetobacter baumannii has emerged as an important nosocomial pathogen. It is difficult to control and treat. The most seriously ill patients and those previously infected are more likely than others to be infected or colonized by A. baumannii. The epidemiology of A. baumannii infection is complex, with the coexistence of epidemic and endemic infections. The A. baumannii are the species isolated in 90% of the nosocomial infections and in 92% of the nosocomial bacteremias. The intensive care units presented the greater number of nosocomial bacteremias by A. baumannii. The most common sources of A. baumannii are respiratory tract, surgical wound, catheter, urinary tract and others. The most frequently clinical manifestation is sepsis and a fulminating course is observed when the patient presents septic shock. Progressive resistance of A. baumannii to antimicrobial limits the therapeutic options. The patients with A. baumannii multidrug-resistant present an excessive rate of attributed mortality, length of stay and costs.

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.

[Multidrug-resistant Acinetobacter baumannii infection in respiratory intensive care unit]

Multidrug-resistant Acinetobacter boumannii is a challenge in the treatment and control of nosocomial infections. This retrospective study was aimed to investigate the prevalence of multidrug resistant A. boumannii in a respiratory intensive care unit (ICU), related risk factors and its impact on disease prognosis. Of 218 patients who were hospitalized in our ICU during the last two years; 37 (17%) patients (21 males, mean age 61.6 +/- 19.8 years) developed pneumonia and/or bacteremia due to multidrug-resistant A. baumannii. Previous antibiotic therapy was detected in 51.4% and hospitalization in 70.3% of the cases. Pneumonia (59.5%) was the most frequent cause of hospitalization and chronic obstructive pulmonary disease (21.6%) was the second one; 81.1% of patients had co-morbidity. Invasive mechanical ventilation was performed in 31 (83.7%) patients during the follow-up. Ventilator-associated pneumonia developed in 22 (59.5%) patients and bacteraemia in 9 (24.3%) patients. Multidrug-resistance was observed in 23 (62.2%) of patients. Highest rates of resistance (100%) was detected against piperacillin-tazobactam, ampicillin-sulbactam and ciprofloxacin, followed by imipenem and cefepime (78%), meropenem and ceftazidime (55%), cefoperazone-sulbactam (43%) and netilmicin (35.1). The rates of re-intubation and tracheotomy were higher in patients infected with A. boumannii compared to the control group (59.5% vs. 7.7%, p < 0.0001 and 21.6% vs. 3.9%, p = 0.001, respectively). There was no significant difference between two groups in terms of mortality, however, durations of ICU and hospital stays were longer in patients with multidrug-resistant A. baumannii infection than without infection (24.2 +/- 18.3 vs. 8.2 +/- 8.3 days, p < 0.001 and 33.3 +/- 19.8 vs. 15.4 +/- 11.4 days, p < 0.001, respectively). In conclusion, due to the high rates of drug-resistance in nosocomial A.baumannii isolates, the use of invasive procedures and durations of ICU and hospital stays exhibit an increasing trend.

Acinetobacter-- serious danger for burn patients

A retrospective study of infection in burn patients admitted to the Clinic for Burns and Reconstructive Surgery Kosice-Saca in the period 2003 to 2006 confirms the increased trend of Acinetobacter (Acb) strains, as a multi-drug-resistant potential pathogen. Over 270 patients are admitted every year to our burn clinic with serious burn injuries, and 75 (on average) to the ICU. Since 1992 the bacterial strain A. baumannii has been sporadically isolated from the wound swabs of the patients admitted to Intensive Care Units (ICU); in 1999 there was a rapid increase in the number of isolates of A. baumannii with increasing resistance to the usual antimicrobials, without clinical manifestation. In 2003, 11% of all hospitalized patients were colonized with A. baumannii, but in 2004 the figure for patients in ICU was 10%. In 2006, 3 patients developed sepsis, 5 patients had uroinfection, 2 patients had pneumonia, and 7 patients had serious wound infections. Wound colonization was confirmed in 17 patients that year. A. baumanii resistance significantly increased after 2003, before the introduction of effective antibiotics against A. baumannii: Ampicilin/Sulbactam (from 16% to 55%), Gentamycin (72%-90%), and Meropenem (from 0% to 4%). The first multi-drug-resistant Acinetobacter baumannii was recorded in 2006 in 8 patients (11%); two patients died of sepsis. Consequently, intensive surveillance of A. baumannii isolates was initiated. The objectives of this investigation were to define the epidemiology of the outbreak and to determine the risk factors for colonization or infection with A. baumannii.

Acinetobacter pneumonia: a review

Acinetobacter species are becoming a major cause of nosocomial infections, including hospital-acquired and ventilator-associated pneumonia. Acinetobacter species have become increasingly resistant to antibiotics over the past several years and currently present a significant challenge in treating these infections. Physicians now rely on older agents, such as polymyxins (colistin), for treatment. This paper reviews the epidemiology, treatment, and prevention of this emerging pathogen.

Novel therapies of multidrug-resistant Pseudomonas aeruginosa and Acinetobacter spp . infections: the state of the art

Gram-negative non-fermenting bacilli, particularly Pseudomonas aeruginosa and Acinetobacter spp., are important opportunistic pathogens in hosppitalized patients, contributing to their morbidity and mortality. Recently, a rapid increase in frequency of multidrug-resistant clinical strains is being recorded, making the available therapeutic options very limited. Apart from the development of novel classes of antimicrobials, there is renewed interest in the use of old agents or new combinations of available drugs. Numerous in vitro investigations have been reported on the efficacy of different antimicrobials; however, they should be evaluated in experimental infection models and clinical trials. Novel approaches are being investigated, such as inhibition of virulence factor expression by pathogens or inhibition of their metabolic pathways. The use of bacteriophages, particularly those genetically modified, remains an alternative option in the therapy of infections caused by multidrug-resistant strains. Several vaccines against P. aeruginosa are under development. Apart from therapy with antimicrobial agents, eradication of outbreaks comprises implementation of strict infection control measures and prudent use of antimicrobials.

Prosthetic Valve Endocarditis Caused by Acinetobacter lwoffi

We are reporting a case of recurrent prosthetic-valve endocarditis (PVE) caused by an unusual pathogen. The patient suffered 2 consecutive relapses of Acinetobacter lwoffi bacteremia, although he had completed a full course of treatment with antibiotics to which the microorganism was susceptible. He was finally successfully operated with replacement of the infected aortic valve. Acinetobacter spp are relatively low-grade but potentially virulent pathogens, and endocarditis caused by these species can be fulminant, accompanied by septic complications, and fatal. Although some patients with relapsed PVE may respond to a second course of antibiotics and medical treatment rather than early valve replacement is suggested in A lwoffi PVE, combined antibiotic treatment and early surgical intervention may be considered as the first option in these patients. There are only a few cases of Acinetobacter endocarditis in the literature, and it is the first case reported in Greece to our knowledge.

Acinetobacter and Staphylococcus Aureus Ulcerative Keratitis After Laser in situ Keratomileusis Treated With Antibiotics and Phototherapeutic Keratectomy

PURPOSE

To report a method of treatment for through-the-flap multibacterial ulcerative keratitis after laser in situ keratomileusis (LASIK).

METHODS

Bacterial ulcerative keratitis after LASIK was treated with topical and systemic antibiotics followed by flap lifting, cleaning, and phototherapeutic keratectomy (PTK). Follow-up examinations included in vivo confocal microscopy, corneal topography, and wavefront analysis.

RESULTS

Rapid recovery of the ulcerative keratitis was observed after flap lifting and cleaning of the interface and PTK combined with topical and systemic antibiotics. Two years postoperatively, corneal topography showed a slight depression of the ulcer area and decentration of the photoablation. Wavefront analysis revealed an irregular scan with a pronounced coma-like aberration, which with a wavefront-guided custom test lens correction provided 20/16 visual acuity.

CONCLUSIONS

Ulcerative bacterial keratitis is a possible sight-threatening complication of LASIK refractive surgery. Lifting and rinsing the flap combined with cleaning of the flap interface with PTK may be helpful in these conditions when regression of the ulcer does not occur with topical and oral antibiotic treatment.

Relapsing peritonitis in continuous ambulatory peritoneal dialysis and an unconventional approach to treatment

Relapsing peritonitis is usually attributable to persistent catheter infection, assuming that the appropriate antibiotic is used to treat each time and that intraabdominal pathology has been ruled out. Removal of the peritoneal dialysis (PD) catheter frequently is curative. We describe here a case in which partial removal of a presternal catheter resulted in resolution of relapsing peritonitis.

Endophthalmitis caused by Acinetobacter calcoaceticus. A profile

PURPOSE

To report the clinical and microbiological profile of endophthalmitis caused by Acinetobacter calcoaceticus.

METHODS

A retrospective study of case series of Acinetobacter calcoaceticus endophthalmitis. Outcome measures included ability to sterilise the eye, anatomical result (clear media and attached retina) and visual recovery (visual acuity > 6/60).

RESULTS

Of the 20 cases studied, 10 were cases of postoperative endophthalmitis, 3 were posttraumatic, 6 were endogenous and one was bleb-related endophthalmitis. Specific features of interest observed were relative chronicity of presentation and absence of any obvious predisposing factor in endogenous endophthalmitis cases. All cases could be sterilised except one, which needed evisceration. Cases with postoperative endophthalmitis had better anatomical outcome (7/10 with attached retina and clear media) and visual outcome (4/10 regained vision > 6/18). Higher smear positivity was seen in vitreous samples (72.2%) compared to aqueous samples (37.5%). Culture positivity was higher from the vitreous cavity compared to aqueous. The organism was sensitive to ciprofloxacin in a high percentage (88.9%) of cases.

CONCLUSIONS

Visual recovery in Acinetobacter calcoaceticus endophthalmitis is modest. Ciprofloxacin is the antibiotic of choice.

[The treatment of necrotizing otitis externa with a combination of surgery, antibiotics, specific immunoglobulins and hyperbaric oxygen therapy. Results of the Ulm Treatment Concept]

BACKGROUND

Even today, necrotizing otitis externa is still a life-threatening condition. The standard treatment concepts based on antibiotic therapy, topical treatment and--if necessary--surgical debridement of necrotic tissue, remain ineffective in many cases. In advanced stages, necrotizing otitis externa can therefore be expected to result in severe functional impairment or even a fatal outcome.

PATIENTS AND METHODS

We describe our experience with a multimodal treatment concept that we have been using with great success at the Federal Armed Forces Hospital in Ulm since 1987. This treatment is based on four pillars: 1. Surgical debridement, 2. Use of a combination of antibiotics, and 3. Administration of specific immunoglobulins, accompanied by, 4. Hyperbaric oxygen therapy

RESULTS

Over a period of more than 5 years 16 of the 22 patients treated on the basis of this multimodal concept remained free of recurrences. In addition, significant reductions in analgesic use and in the insulin doses needed by diabetic patients were possible.

CONCLUSIONS

The treatment concept under scrutiny has proved particularly successful. The various modes involved and the results of this combined therapy are discussed.

[Therapeutical options in partial infected aorto- bifemoral prosthetic grafts]

PURPOSE

To asses the use of synthetic or autologous conduits for the reconstruction of iliofemural sector in the cases of partial, limited infections of aortobifemural prosthetic grafts.

METHOD

We present two cases, both of them with infection recognized at the groin; the first one by a vascular fistula bleeding intermittently, the second by a draining groin sinus with fever and leukocytosis.

RESULTS

The PTFE conduit was the material utilized at the first case and the superficial femoral vein in the second case. The patients presented completed resolution of the infectious signs and symptoms and the revascularisation of the legs was successfully done. Evan with an extra-anatomical bridge or an autogenous material, sometimes is possible to resolve a regional infection of the aortobifemural graft only with a partial resection of one leg of the prosthesis and replacing with another sterile material.

Eradication of multi-drug resistant Acinetobacter from an intensive care unit

BACKGROUND

Acinetobacter baumannii is a gram-negative coccobacillus that causes outbreaks of nosocomial infections in ICUs. Due to resistance to multiple antibiotics, management of clusters of A. baumannii is useful as a model in eradication of multi-drug resistant infections. We outline the evolution of an A. baumannii outbreak, focusing on methods of transmission and multidisciplinary measures aimed at eliminating it from the ICU.

METHODS

Patients in an urban, tertiary care medical center from November 1996 to December 1997 having positive cultures for multi-drug resistant A. baumannii are included in this study. A. baumannii was isolated on blood agar and MacConkey cultures and identified by Vitek panel. Disk diffusion including amikacin, imipenem, polymyxin B, and sulbactam were used to determine resistance.

RESULTS

An outbreak of 52 patients (27 infected, 25 colonized) with 68 positive sites began with the transfer of a colonized >50% total body surface area burn patient from an outside hospital. Within 3 days, the index patient was in the burn ICU, coronary care unit, and medical ICU. Soon, clusters of patients with A. baumannii infections sensitive only to polymyxin B were seen in those units and, ultimately, the surgical ICU. On typing, 2 strains were found, PFGE B and C. Given the level of antibiotic resistance, patients with colonization or infection were cohorted and placed on contact isolation. Strict antiseptic measures, such as hand-washing, barrier isolation, equipment and room cleaning, sterilization of ventilator equipment, and dedication of medical equipment to each patient were instituted. Still, positive environmental cultures were found in ventilator water traps, sinks, and bedrails. Sporadic cases continued for a total of 13 months, with 10 deaths resulting from the infections.

CONCLUSION

A. baumannii is a mildly virulent organism that becomes resistant to antimicrobials. Because of multiple antibiotic resistance, strict contact isolation cohorting and antiseptic technique are the primary modes of containment. This outbreak serves as a model of eradication of multi-drug resistant organisms from ICUs. These measures will become of greater importance as nosocomial organisms develop increasing resistance to antimicrobials.

Bronchoalveolar interleukin-1 beta: a marker of bacterial burden in mechanically ventilated patients with community-acquired pneumonia

OBJECTIVE

To assess the relationship between concentrations of bronchoalveolar cytokines and bacterial burden (quantitative bacterial count) in intubated patients with a presumptive diagnosis of community-acquired pneumonia.

DESIGN

A cross-sectional and clinical investigation. SETTING Medical/surgical and respiratory intensive care unit of a tertiary 1,200-bed medical center.

PATIENTS

According to the time course of community-acquired pneumonia at the time of study with bronchoalveolar lavage, 69 mechanically ventilated patients were divided into three subgroups: primary (n = 11), referral (n = 23), and treated (n = 35) community-acquired pneumonia.

INTERVENTIONS

Bronchoalveolar lavage was performed in the most abnormal area on chest radiograph by fiberoptic bronchoscope. Bronchoalveolar lavage fluid was processed for quantitative bacterial culture. The concentrations of bronchoalveolar lavage cytokines (tumor necrosis factor-alpha, interleukin-1 beta, interleukin-6, interleukin-8, and interleukin-10) also were measured.

MEASUREMENTS AND MAIN RESULTS

Thirty-two patients had a positive bacterial culture (bronchoalveolar lavage > or = 10 colony-forming units/mL)., and made up 76% of pathogens recovered at high concentrations. The concentrations of bronchoalveolar lavage interleukin-1 beta were 199.1 +/- 32.1 and 54.9 +/- 13.0 pg/mL (mean +/- se) in the patients with positive and negative bacterial culture, respectively (p < .001). Bronchoalveolar lavage interleukin- 1 beta was significantly higher in the patients with a high bacterial burden (p < .001), with mixed bacterial infection (p < .001), and with pneumonia (p < .001), compared with values in patients without these features. The relationship between bacterial load and concentrations of bronchoalveolar lavage interleukin-1 beta was very strong in the patients with primary and referral community-acquired pneumonia but was borderline in treated community-acquired pneumonia.

CONCLUSIONS

The common pathogens were similar to the core pathogens of hospital-acquired pneumonia, probably due to antibiotic effects, delayed sampling, and superimposed nosocomial infection. Since the concentration of bronchoalveolar lavage interleukin-1 beta was correlated with bacterial burden in the alveoli, it may be a marker for progressive and ongoing inflammation in patients who have not responded to pneumonia therapy and who have persistence of bacteria in the lung.

Thyroid abscess due to Acinetobacter calcoaceticus: case report and review of the causes of and current management strategies for thyroid abscesses

Thyroid abscess was a common condition in the era before antibiotics. In the current medical environment, however, it is a clinical entity that is seldom encountered. We report the case of a unique cause of thyroid abscess, the environmental Gram-negative bacterium Acinetobacter calcoaceticus. Review of the published causes of thyroid abscess since 1980 demonstrated that although Gram-positive bacteria (Staphylococcus and Streptococcus species) remain the most common causes, there has been a marked decrease in the number of cases caused by mycobacteria, Salmonella species, and anaerobes when compared with the early part of the 20th century. Patients infected with the human immunodeficiency virus, however, still develop mycobacterial and fungal thyroid infections with some regularity. Reported modes of management of thyroid abscess vary, but drainage remains an integral component of therapy for resolution of the infection.

[Nosocomial infection/colonization of the respiratory tract caused by Acinetobacter baumannii in an Internal Medicine ward]

BACKGROUND

To present the epidemiology of the outbreak and the description of patients with infection or colonization of the respiratory tract caused by A. baumannii in an Internal Medicine ward.

METHODS

20 consecutively patients hospitalized in the Internal Medicine ward were studied during 18 months with isolation of multiresistant A. baumanni in respiratory tract specimens with or without clinical signs of infection.

RESULTS

Starting on an index case, that was a patient coming from other hospital with diagnosis of nosocomial Acinetobacter pneumonia, we detected 20 patients. The age of the patients ranged from 48 to 95 years, with a mean of 71.4 years. Eighty percent were males. The clinical features were similar: advanced age, with chronic diseases (35 percent diabetics, 45 percent with chronic lung diseases), and use of broad-spectrum antibiotics agents, fundamentally third generation cephalosporin (70 percent), clarithromycin (55 percent) and quinolones (30 percent). 75 percent of patients were in the same ward. Eight (40 percent) of the patients with chronic lung diseases were subjects with COPD, two with asthma and chronic glucocorticoids treatment, and one with a sleep apnea. In four cases the isolation was considered a colonization. The mean stay was 26.15 days, and the mortality 40 percent.

CONCLUSIONS

The nosocomial infection caused by Acinetobacter baumannii is responsible of a high morbi-mortality between the patients hospitalized in an Internal Medicine ward, and produce an increase in length of stay. It is necessary a combination of control measures to prevent the transmission in the hospital and the outbreak of new multiresistant strains.

[Community-acquired Acinetobacter baumannii pneumonia]

We report two cases of community-acquired Acinetobacter baumannii pneumonia. Although most infections occur in hospitalized patients, a few cases of community-acquired pneumonia have been described. This disease occurs predominantly in men, and is often associated with underlying conditions such as cigarette smoking, alcohol abuse, diabetes mellitus, and chronic pulmonary diseases. Community-acquired Acinetobacter baumannii pneumonia cases are generally reported from tropical areas, especially during wet season. Microbiological identification in blood or sputum can be difficult because of frequent misinterpretation and possible confusion with Staphylococcus or Haemophilus infuenzae or neisseriae. Early antibiotherapy is required because of the fulminant clinical course, with approximatively 50% fatality rate.

Acinetobacter calcoaceticus pneumonia and the formation of pneumatoceles

Pneumatoceles are cystic lesions of the lungs often seen in children with staphylococcal pneumonia and positive-pressure ventilation. Acinetobacter calcoaceticus is an aerobic, short immobile gram-negative rod, or coccobacillus, which is an omnipresent saprophyte. The variant anitratus is the most clinically significant pathogen in this family, usually presenting as a lower respiratory tract infection. Acinetobacter has been demonstrated to be one of the most common organisms found in the ICU. We present three critically ill surgery patients with Acinetobacter pneumonia, high inspiratory pressures, and the subsequent development of pneumatoceles. One of these patients died from a ruptured pneumatocele, resulting in tension pneumothorax. Treatment of pneumatoceles should center on appropriate intravenous antimicrobial therapy. This should be culture directed but is most often accomplished with Imipenem. Percutaneous, computed tomographic-guided catheter placement or direct tube thoracostomy decompression of the pneumatocele may prevent subsequent rupture and potentially lethal tension pneumothorax.

Infective endocarditis of an interventricular patch caused by Acinetobacter haemolyticus

A case of infective endocarditis caused by Acinetobacter haemolyticus affecting and interventricular patch is reported. The patient, a 21-year-old man with a Fallot's tetralogy who had undergone cardiovascular surgery several years before, received imipenem and gentamicin for 6 and 4 weeks respectively and showed a good response without needing surgical treatment. Endocarditis by Acinetobacter species is very unusual and, to our knowledge, this is the first reported case of infective endocarditis caused by A. haemolyticus. As the clinical characteristics and the response to antibiotics appear to be similar to those reported for infective endocarditis by Acinetobacter lwoffi, prosthetic infective endocarditis by A. haemolyticus is apparently not always an indication for surgical treatment.

Treatment of experimental infections of mice with bacteriophages

Bacteriophages for Acinetobacter baumanii, Pseudomonas aeruginosa and Staphylococcus aureus were tested in experimental infections of mice to investigate their potential for the treatment of infections of man. As few as 10(2) particles of an acinetobacter phage protected mice against 5 LD50 (1 x 10(8)) of a virulent strain of A. baumanii, and phage was demonstrated to have multiplied in the mice. A pseudomonas phage protected mice against 5 LD50 of a virulent strain of P. aeruginosa, with a PD50 of 1.2 x 10(7) particles. A staphylococcal phage failed to protect mice infected with a strain of S. aureus. These studies support the view that bacteriophages could be useful in the treatment of human infections caused by antibiotic-resistant strains of bacteria.

Infection with Acinetobacter in a burns unit

In recent months 17 patients on the Burns Unit at St Lawrence Hospital have been infected with Acinetobacter anitratus. We present 4 patients who have been extremely ill and in whom Acinetobacter was considered to have played a prominent role. We stress the importance of opportunistic infection in burns patients and antibiotic resistance in this organism.

Ventriculitis from Acinetobacter calcoaceticus variant anitratus

Ventriculitis from infection with Acinetobacter calcoaceticus variant anitratus occurred in an infant two weeks after surgical repair of a lumbosacral meningomyelocele and ventriculoperitoneal shunting. Recovery took place on replacing the shunt with an extraventricular deviation device and giving gentamicin and ampicillin intravenously.