Tuesday, February 26, 2013

Gram-negative Bacteria Infections

Gram-negative Bacteria Infections

General Information about gram-negative bacteria.

Gram-negative bacteria cause infections including pneumonia, bloodstream infections, wound or surgical site infections, and meningitis in healthcare settings. Gram-negative bacteria are resistant to multiple drugs and are increasingly resistant to most available antibiotics. These bacteria have built-in abilities to find new ways to be resistant and can pass along genetic materials that allow other bacteria to become drug-resistant as well. CDC’s aggressive recommendations, if implemented, can prevent the spread of gram-negatives.
Gram-negative infections include those caused by KlebsiellaAcinetobacter, Pseudomonas aeruginosa, and E. coli., as well as many other less common bacteria.

CDC guidelines to address gram-negative bacteria

  • CDC Multi-Drug Resistant Organism Guidelines address reducing infections caused by all drug-resistant bacteria, including gram negatives.
  • CDC Guidance for Control of Infections with Carbapenem-resistant or Carbapenemase-producing Enterobacteriaceae in Acute Care Facilities contains specific recommendations for prevention and control of a specific emerging drug-resistant gram-negative.    

    Outbreak investigations

    Outbreak investigations have led to a better understanding of how to control these bacteria in healthcare. In the past 3 years, the Division of Healthcare Quality Promotion has assisted in at least 10 investigations of outbreaks of gram negative infections.
      • CDC has collaborated with state health departments in Maryland and Arizona to successfully control outbreaks of Multidrug-resistant-Acinetobacter infections occurring among intensive care unit patients.
      • CDC has worked with the Puerto Rico health department to control an outbreak of highly resistant Klebsiella at a neonatal intensive-care unit in Puerto Rico.
      • CDC assisted the Ohio health department’s investigation of infections caused by Acinetobacter. These outbreaks have occurred in various healthcare facilities in the state of Ohio and have been controlled by aggressive infection control interventions.
      • CDC worked with the state health department of Texas on separate outbreaks of B. cepacia and Pseudomonas
      • Additionally, CDC worked with the state health department in Georgia on an unrelated outbreak of B. cepacia.
      • CDC worked with the Department of Defense to investigate and control Acinetobacter infections occurring in soldiers injured in the Middle East. This collaboration led to important improvements in infection control in military medical facilities.
    • In addition to these outbreaks, CDC’s reference laboratory has confirmed carbapenemase resistance in bacteria for 32 other U.S. states.

    Laboratory tests for detecting resistance

    • CDC is collaborating with laboratory standards-setting institutions to identify and recommend laboratory tests for the accurate detection of carbapenemase-mediated resistance.  
    • CDC is working with states to identify isolates with unusual resistance and to determine new mechanisms of resistance among multidrug-resistant gram-negatives, including the recent identification of a new mechanism of resistance in patients returning from Asia.

    Monitoring gram-negative healthcare-associated infections

    • CDC’s National Healthcare Safety Network (NHSN) captures information on antibiotic resistance patterns in gram-negative bacteria in healthcare settings. 
    • The percentage of gram-negatives that are resistant to drugs is increasing. 
    • In 2008, based on NHSN data, 13% of E. coli and Klebsiella, 17% of P. aeruginosa and 74% of A. baumannii in intensive-care units were multidrug-resistant.

Pseudomonas bacteria

*Thought it might be good to have a brief apge on Psuedomonas, as it is an infection that so many lymphedema patients (including myself) see to "catch."*
Pseudomonas bacteria are any bacteria of the Pseudomonas genus of gamma proteobacteria. This type of bacteria is often infectious and has many characteristics in common with other pathogenic bacteria. They occur very commonly in water and some types of plant seeds, and for this reason, were observed very early on in the history of microbiology. The name Pseudomonas literally means “false unit.”
Pseudomonas bacteria are rod-shaped like many other bacterial strains, and are Gram-negative. This means that when stained with a certain violet-red dye according to the Gram staining protocol, they do not retain the dye’s color after being washed. This fact gives important clues about the structure of the cell wall of Pseudomonas bacteria. It shows that it is resistant to certain types of antibiotics, which fact is proving to be increasingly relevant.
One type of Pseudomonas bacteria is the Pseudomonas aeruginosa, which is responsible for an increasing number of infections in hospital patients, particularly those suffering from cancer or severe burns. This opportunistic pathogen has very minimal nutritional requirements, evidenced by the fact that it has been found growing in distilled water. Its preferred temperature for growth is 98.6 degrees Fahrenheit (37 degrees C), making it especially suited for infecting the tissues of the human body. It is important to note, though, that this bacterium is often found harmlessly on the skin and in the bodies of healthy persons.
Some kinds of Pseudomonas bacteria are also pathogenic to plant life. Many of these, interestingly enough, show a tendency to only infect certain plants in certain ways, and to use specific tactics in doing so. Even when not strictly a plant pathogen, Pseudomonas bacteria can affect agriculture in other ways, often causing problems in the cultivation of mushrooms.
Because of the infectious nature of these bacteria, they can actually be used to combat other agricultural pathogens. Since the 1980s, certain types of Pseudomonas bacteria, such as Pseudomonas fluorescens, have been applied directly to soils and seeds in order to prevent the growth of crop pathogens. This practice of deterring one type of pathogen with another is generally referred to as biocontrol. Another member of the Pseudomonas genus which has biocontrol properties is Pseudomonas chlororaphis, which itself produces an antibiotic which is active against certain fungi that attack plants. There is still much study to be done in the area of biocontrol, and Pseudomonas bacteria may yet prove to have additional helpful qualities.

From Wisegeek

Wednesday, February 13, 2013

Role of Bacterial Lipopolysaccharide in Enhancing Host Immune Response to Candida albicans.

Role of Bacterial Lipopolysaccharide in Enhancing Host Immune Response to Candida albicans.



Tissue Engineering and Reparative Dentistry, School of Dentistry, College of Biomedical and Life Sciences, Cardiff University, Heath Park, Cardiff CF14 4XY, UK.


Human infections involving yeast of the genus Candida often occur in the presence of bacteria, and, as such, it is important to understand how these bacteria influence innate host immunity towards Candida. Dectin-1 is a cell receptor of macrophages for Candida albicans recognition. The aim of this study was to examine dectin-1 expression by monocytes after stimulation with bacterial lipopolysaccharide (LPS), followed by heat-killed C. albicans (HKC). Freshly isolated human peripheral blood monocytes (PBMCs) and human monocytes cell line (THP-1) cells expressed low levels of dectin-1. Stimulation with LPS and GM-CSF/IL-4 was found to increase dectin-1 expression in both CD14(+) human PBMC and THP-1 cells. Enhanced dectin-1 expression resulted in increased phagocytosis of Candida. When THP-1 cells were challenged only with HKC, detectable levels of IL-23 were not evident. However, challenge by LPS followed by varying concentrations of HKC resulted in increased IL-23 expression by THP-1 cells in HKC dose-dependent manner. Increased expression of IL-17 by PBMC also occurred after stimulation with Candida and LPS. In conclusion, bacterial LPS induces an enhanced immune response to Candida by immune cells, and this occurs through increasing dectin-1 expression.

Thursday, February 7, 2013

Symptom burden and infection occurrence among individuals with extremity lymphedema.

Symptom burden and infection occurrence among individuals with extremity lymphedema.



School of Nursing, Vanderbilt University, Nashville, TN 37240, USA. sheila.ridner@vanderbilt.edu


Currently, there is a lack of data related to differences in symptoms and infection across different types and anatomical sites of lymphedema. The objective of this study was to examine differences in symptoms and infection status among individuals with lymphedema of the upper or lower extremities. The National Lymphedema Network initiated an online survey of self-report lymphedema data from March 2006 through January 2010. Descriptive statistics, Mann-Whitney tests, and Chi-square tests were used to analyze data. 723 individuals with upper extremity lymphedema and 1114 individuals with lower extremity ymphedema completed the survey. Individuals with extremity lymphedema experienced high symptom burden and infectious complications. Compared with individuals with upper extremity lymphedema, individuals with lower extremity lymphedema experienced more frequent and more severe symptoms (p<.001), infection episodes (p<.001), and infection-related hospitalizations (p<.001). No statistically significant differences of symptom burden and infection status were identified between individuals with lower extremity primary and secondary lymphedema. Individuals with extremity lymphedema experience substantial symptom burden and infectious complications; however, those with lower extremity lymphedema have more severe symptoms and more infections than those with upper extremity lymphedema.