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Exclusion criteria were readmission to the MSICU within 30 days, and patients admitted to the unit for short-term post-operative monitoring.
Computerized medical records were reviewed and clinical information was abstracted for each patient. Institutional Review Board of the hospital approved the study. BSI was defined as infection confirmed by blood culture. Among the Gram-positive organisms, MDR was defined as methicillin resistance in Staphylococcus aureus and vancomycin resistance in Enterococcus spp. Polymicrobial BSI was described as the recovery of different organisms from one or more blood cultures within the same BSI episode [ 8 ].
Laboratory methods and susceptibility testing At least one set of blood culture per patient was drawn, and then sent to a reference microbiology laboratory Kings County Hospital, New York for processing. Isolates of microorganisms were identified by conventional biochemical and serological methods. A BSI was defined as isolation of at least one positive peripheral blood culture, except cases of infection with coagulase-negative staphylococci CNS , for which isolation of two positive blood cultures was required.
Antimicrobial susceptibility testing of isolated pathogens to clinically relevant antimicrobials was performed by using MicroScan panels or the Kirby Bauer diffusion methods, according to the guidelines published by the Clinical and Laboratory Standards Institute CLSI. Susceptibilities for linezolid, daptomycin, and tigecycline in cases of methicillin-resistant Staphylococcus aureus MRSA and vancomycin-resistant Enterococcus VRE were performed as per physician request, and not on routine basis.
Gram-negative organisms were tested for ESBL production in cases of isolates with reduced susceptibility to ceftriaxone or ceftazidime.
ESBL and carbapenem-resistant organisms were tested for susceptibility to polymyxins as per physician request. Susceptibility testing was not routinely performed for fungal organisms. Ninety-one The median age was 64 years A total of 20 patients Among the Enterococcus spp, 8 isolates All Streptococcus pneumoniae isolates were susceptible to penicillin.
A total of 13 The most common risk factors for MDR infections were diabetes mellitus and malignancy. Aspergillus niger was identified from one isolate, and was considered as environmental contaminant.
Discussion The global escalation in both community- and hospital-acquired antimicrobial-resistant bacteria is increasingly compromising effective antimicrobial therapy, particularly when it comes to empiric antimicrobial selection.
In the battle against MDR, several behavioral changes have been proposed to reduce or to improve antimicrobial therapy. However, the use of broad-spectrum antimicrobials in critically ill patients is deemed necessary due to small margins for error in choice of therapy, where initial selection of antimicrobials covering offending pathogens is of extreme importance [ 11 ]. Lipsitch et al concluded that use of antimicrobials for which resistance is not present will be positively associated at the individual level with carriage of bacteria resistant to another antimicrobial but negatively associated at the population level with the prevalence of resistance to the other antimicrobial [ 12 ].
Mortality seems to be strictly related to the severity of infection, underlying diseases, advanced age, and inadequate antimicrobial therapy. In our study, there was a slightly higher prevalence of Gram-positive bacteria over Gram-negative organisms causing BSI.
MRSA has emerged as the most common hospital acquired pathogen. Historically, vancomycin has been the cornerstone of treatment for patients with serious MRSA infections. As outlined in our report, the median MIC for vancomycin was 2. Unfortunately, susceptibility testing for linezolid, daptomycin, or tigecycline was not performed on routine basis.
In a large prospective surveillance study, Zhanel et al reported that Overall, it was the most commonly isolated organism in this study. In most cases are considered contaminants rather than a cause of true infection. Although distinguishing contaminant from true infection remains difficult without a gold standard, the rate of blood cultures contaminated with CNS in this report was much higher than in other studies [ 25 ], but similar to USA rates [ 17 ].
The emergence of VRE as an increasingly common nosocomial pathogen has created a formidable challenge for both clinicians and infection control officers since it was first described in [ 26 ]. In those patients, colonization occurs predominantly in the gastrointestinal tract facilitating widespread of the organism within hospitals.
Vancomycin administration in patients already colonized with VRE significantly increased the risk of prolonged VRE carriage, playing a critical role in the nosocomial epidemiology of this organism [ 27 ].
The results of this study showed an overwhelming high rate of VRE In one study, Zhanel et al reported that 6. Carbapenams antimicrobials are considered the first-line therapy for ESBL infections, but resistance to this antimicrobial class is becoming widespread. In several reports, the nationwide resistance percentage remained high, which suggests that this phenotype may be more widespread and more common than previously recognized [ 31 , 32 ].
Kallen et al reported 15, isolates of Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae from hospitals in USA. Exposure to long-term care facilities and previous exposure to broad-spectrum antimicrobials are risk factors that have been consistently associated with CRE infections.
Not surprisingly, patients with carbapenem-resistant infections also have significant comorbidities. It was most commonly found in Klebsiella pneumoniae and Acinetobacter baumannii isolates, similar as in previous studies. Literature regarding appropriate therapy for CRE infections is limited, as are the options of clinically available antimicrobials. Given the restricted antimicrobial options and the potential for further resistance to develop, most institutions have focused on aggressive infection control policies to limit transmission.
In our institution, empiric antimicrobial regimens composed by vancomycin plus a 4th-generation cephalosporin cefepime , or an anti-pseudomonal penicillin piperacillin-tazobactam , or a carbapenem doripenem , with or without a macrolide azithromycin or a fluoroquinolone moxifloxacin is usually initiated in patients admitted with sepsis with or without septic shock.
Although this report does not address patient outcomes, the suboptimal selection of empiric antimicrobial therapy for those patients likely had adverse impact on survival, and surely in length of stay and hospital costs. It is also important to address the higher rate 9.
Significant regional and geographic variations exist in the incidence of the different Candida spp. Candida glabrata is generally the second most commonly isolated pathogen in North America [ 13 , 40 ]. Our results showed slight predominance of non-albicans spp. The gold standard diagnostic test for invasive candidiasis has been isolation of the organism by blood culture. Detection of candidemia by blood culture often takes more than 24 hours.
For certain spp, such as Candida glabrata, the time can be even longer, leading to a significant delay in appropriate therapy and higher mortality [ 42 , 43 ]. None of the patients included in this study were receiving empiric antifungal therapy at the time the fungal organisms were isolated. It is difficult to quantify the burden of disease, expressed as increased mortality or prolonged length of stays due to infections caused by these antimicrobial-resistant organisms.
Routine surveillance cultures to steer empiric antimicrobial therapy may result in higher rates of initial appropriate therapy while including a substantial potential in the savings of last-line antimicrobial agents [ 44 ]. Specific impact of preventive measures certainly depends on the local epidemiology and resistance levels.
Infection control measures have important implications for daily practice, because more patients are already colonized with MDR organisms on arrival to ICU. Therefore, broad empiric antimicrobial coverage may be needed in several patients admitted to these units. In the absence of new antimicrobials, prevention of infections and optimizing adherence to universal infection control measures, along with restriction of antimicrobials consumption by a sensible hospital drug policy such as antimicrobial stewardships and promotion of a rational use of antibiotics, should stop or decreased the rising of MDR.
Conflicts of Interest No conflicts of interest among authors.
References 1. The rising problem of antimicrobial resistance in the intensive care unit. Ann Intensive Care. Prabaker K, Weinstein RA. Trends in antimicrobial resistance in intensive care units in the United States. Curr Opin Crit Care. Predictors of mortality in patients with bloodstream infection due to ceftazidime-resistant Klebsiella pneumoniae. Antimicrob Agents Chemother.
Once a film of bacteria forms, it is easier for other marine organisms such as barnacles to attach. Time in dry dock for refitting and repainting reduces the productivity of shipping assets, and the useful life of ships is also reduced due to corrosion and mechanical removal scraping of marine organisms from ships' hulls. Stromatolites are layered accretionary structures formed in shallow water by the trapping, binding and cementation of sedimentary grains by microbial biofilms, especially of cyanobacteria.
Stromatolites include some of the most ancient records of life on Earth, and are still forming today. Dental plaque[ edit ] Within the human body, biofilms are present on the teeth as dental plaque , where they may cause tooth decay and gum disease. These biofilms can either be in an uncalcified state that can be removed by dental instruments, or a calcified state which is more difficult to remove. Removal techniques can also include antimicrobials. The accumulation of microorganisms subjects the teeth and gingival tissues to high concentrations of bacterial metabolites which results in dental disease.
An ecologic shift away from balanced populations within the dental biofilm is driven by certain cariogenic microbiological populations beginning to dominate when the environment favours them.
The shift to an acidogenic , aciduric, and cariogenic microbiological population develops and is maintained by frequent consumption of fermentable dietary carbohydrate.
The resulting activity shift in the biofilm and resulting acid production within the biofilm, at the tooth surface is associated with an imbalance between demineralization and remineralisation leading to net mineral loss within dental hard tissues enamel and then dentin , the sign and symptom being a carious lesion.
By preventing the dental plaque biofilm from maturing or by returning it back to a non-cariogenic state, dental caries can be prevented and arrested.
A peptide pheromone quorum sensing signaling system in S. This system is optimally expressed when S. Biofilm grown S. Many different bacteria form biofilms, including gram-positive e. Bacillus spp, Listeria monocytogenes , Staphylococcus spp, and lactic acid bacteria , including Lactobacillus plantarum and Lactococcus lactis and gram-negative species e.
Escherichia coli , or Pseudomonas aeruginosa. Pseudomonas putida , Pseudomonas fluorescens , and related pseudomonads which are common plant-associated bacteria found on leaves, roots, and in the soil, and the majority of their natural isolates form biofilms. Cryptococcus laurentii  and microalgae. Among microalgae, one of the main progenitors of biofilms are diatoms , which colonise both fresh and marine environments worldwide.
Although many techniques have developed to identify planktonic bacteria in viable wounds, few have been able to quickly and accurately identify bacterial biofilms. Future studies are needed to find means of identifying and monitoring biofilm colonization at the bedside to permit timely initiation of treatment. The patients with biofilms were shown to have been denuded of cilia and goblet cells , unlike the controls without biofilms who had normal cilia and goblet cell morphology.
The species of bacteria from intraoperative cultures did not correspond to the bacteria species in the biofilm on the respective patient's tissue.
In other words, the cultures were negative though the bacteria were present. This sub-therapeutic level of antibiotic may result from the use of antibiotics as growth promoters in agriculture, or during the normal course of antibiotic therapy. The biofilm formation induced by low-level methicillin was inhibited by DNase, suggesting that the sub-therapeutic levels of antibiotic also induce extracellular DNA release.
When S. CSP also functions as a quorum-sensing peptide. It not only induces biofilm formation, but also increases virulence in pneumonia and meningitis. It has been proposed that competence development and biofilm formation is an adaptation of S.
Competent S. No matter the sophistication, microbial infections can develop on all medical devices and tissue engineering constructs. For example, many sewage treatment plants include a secondary treatment stage in which waste water passes over biofilms grown on filters, which extract and digest organic compounds.
In such biofilms, bacteria are mainly responsible for removal of organic matter BOD , while protozoa and rotifers are mainly responsible for removal of suspended solids SS , including pathogens and other microorganisms.
Slow sand filters rely on biofilm development in the same way to filter surface water from lake, spring or river sources for drinking purposes. What we regard as clean water is effectively a waste material to these microcellular organisms. Biofilms can help eliminate petroleum oil from contaminated oceans or marine systems.
The oil is eliminated by the hydrocarbon-degrading activities of microbial communities, in particular by a remarkable recently discovered group of specialists, the so-called hydrocarbonoclastic bacteria HCB. One species of bacteria that can be found in various industries and is a major cause of foodborne disease is Salmonella.
Salmonella is also found in the seafood industry where biofilms form from seafood borne pathogens on the seafood itself as well as in water. These new forms of cleaning procedures also have a profound effect on the environment, often releasing toxic gases into the groundwater reservoirs.
In the marine environment, biofilms could reduce the hydrodynamic efficiency of ships and propellers, lead to pipeline blockage and sensor malfunction, and increase the weight of appliances deployed in seawater.