Saturday, June 30, 2007
Changing Trends in Bacterial Infections: Staphylococcus aureus, Bacterial Pneumonia, Clostridium difficile
Top HIV Med. 2007 Jun-Jul;15
The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Changing bacterial diseases in the general population of which HIV practitioners should be aware include: new staphylococcal syndromes caused by community-acquired methicillin-resistant Staphylococcus aureus USA300 strains (eg, necrotizing skin infections, pneumonia, fasciitis); continued high rates of community-acquired pneumonia in the potent antiretroviral therapy era; increase rates and severity of Clostridium difficile-associated disease due to the fluoroquinolone-resistant NAP1 strain, and the new scare from extensively drug-resistant tuberculosis, primarily as a potential threat to health care in Africa.
This article summarizes a presentation on important bacterial infections made by John G. Bartlett, MD, at the International AIDS Society-USA course in New York in March 2007. The original presentation is available at IAS.
Topics IN HIV
Sunday, June 24, 2007
Vol.297 No.23, June 20, 2007
Lyme disease is an infection caused by a kind of bacteria (germ) called a spirochete. This bacterium, Borrelia burgdorferi, is transmitted by the bite of an infected deer tick. It is the most common tick-borne infection in both North America and Europe. Diagnosis is based on a variety of symptoms, physical findings, blood tests, and a history of exposure to infected ticks. The June 20, 2007, issue of JAMA includes an article that discusses a rash called erythema migrans (see below) as a clinical sign that is consistent with a diagnosis of early Lyme disease and other related tick-borne diseases.
Erythema migrans (EM)—About 70% to 80% of infected individuals will develop a red rash at the site of the tick bite. Over a period of days to weeks, the rash grows larger and the center may fade, creating a "bull's-eye" or ring appearance. The rash rarely may burn or itch.
Arthritis—About 60% of untreated individuals will go on to develop arthritis. The joints become swollen and painful, making daily activities burdensome.
Neurological symptoms—The spread of Lyme disease to the nervous system can cause Bell palsy (a facial droop due to muscle paralysis) or a form of meningitis. Later neurological symptoms may include memory loss, inability to concentrate, and muscle weakness with tingling and numbness in the arms and legs.
Other symptoms—Less common symptoms include eye inflammation (redness and swelling), fatigue, sleep disturbance, stiff neck, fever, and body aches.
Once the diagnosis has been made, Lyme disease is treated with antibiotics. Nonsteroidal anti-inflammatory drugs such as aspirin or ibuprofen are helpful for arthritis symptoms and fever.PREVENTION
The best way to prevent Lyme disease is to prevent tick bites:
Use protective clothing—wear long-sleeved shirts and pants.
Use insect repellents containing DEET or permethrin.
Apply an acaricide (a chemical that kills ticks) to your yard in the spring.
Check your skin, your children's skin, and your pets for ticks after time spent outdoors. The nymph stage of deer ticks, the most important source of Lyme disease transmission, is barely visible (less than 1/16 inch before feeding). You are not likely to get Lyme disease if the tick has been attached to your skin for less than 24 to 48 hours.
Remove plants that attract deer and periodically clean leaves, brush, tall grasses, and woodpiles from around your house.
Minimize exposure to wooded areas and shady grasslands during the spring and summer months.
FOR MORE INFORMATION
Centers for Disease Control and Prevention (CDC) Division of Vector-Borne Infectious Diseases
American Academy of Family Physicians (AAFP)
Monday, June 18, 2007
Bacteriophages: an appraisal of their role in the treatment of bacterial infections.
Int J Antimicrob Agents. 2007 Jun
School of Pharmacy and Biomolecular Sciences, University of Brighton, Moulsecoomb, Brighton BN2 4GJ, UK.
Bacteriophages were first used successfully to treat bacterial infections a decade before penicillin was discovered. However, the excitement that greeted those initial successes was short-lived, as a lack of understanding of basic phage biology subsequently led to a catalogue of clinical failures. As a consequence, bacteriophage therapy was largely abandoned in the West in favour of the newly emerging antibiotics.
Now, as the problem of antibiotic resistance becomes ever more acute, a number of scientists and clinicians are looking again at bacteriophages as a therapeutic option in the treatment of bacterial infections. The chances of success second time round would appear to be much better given our current extensive knowledge of bacteriophage biology following their important role in underpinning the advances in molecular biology.
We also have available to us the experience of nearly 80 years of clinical usage in the countries of the former Soviet Union and Eastern Europe as well as a political climate that encourages sharing of that knowledge.
This review outlines those features of bacteriophages that contribute to their utility in therapy and explores the potential for their re-introduction into Western medicine. An abundance of clinical evidence is available in the Soviet literature but much of this is technically flawed and a more realistic appraisal of the clinical value of phages can be obtained from animal studies conducted in the West. As interest in bacteriophages increases, a number of companies throughout the world have begun investing in phage technology and this has led to novel approaches to therapy, some of which will be discussed.
PMID: 17566713 [PubMed - as supplied by publisher]
Tuesday, June 12, 2007
Phagotrophic protozoa: A new weapon against pathogens?
Phagotrophic protozoa: A new weapon against pathogens?
Med Hypotheses. 2007 Jun 4
Immune suppression is one of the most important factors contributing mortality in systemic diseases like HIV, cancer or diabetes. Moreover, in autoimmune diseases immune suppression itself becomes the only choice of therapy. Finally, fatal bacterial infections occur. As antibiotics get stronger, severity of their side effects increase and more resistant organisms develop. The war between antibiotics and pathogens becomes a never ending story while human body gets weaker day by day. Therefore we should develop new methods against bacterial infections. We have suggested that the protists controlling the bacterial growth effectively in aquatic environments could be used in the human body to cope with human pathogens. Million years of a balanced aquatic ecosystem could be a clue for us to search for better and more natural fighting methods against human infectious agents.Elsevier
Sunday, June 10, 2007
Role of the innate immune system in host defence against bacterial infections: focus on the Toll-like receptors.
J Intern Med. 2007 Jun;
Albiger B, Dahlberg S, Henriques-Normark B, Normark S.
Medical Microbiology, Department of Laboratory Medicine, Lund University, Malmö, Sweden.
The innate immunity plays a critical role in host protection against pathogens and it relies amongst others on pattern recognition receptors such as the Toll-like receptors (TLRs) and the nucleotide-binding oligomerization domains proteins (NOD-like receptors, NLRs) to alert the immune system of the presence of invading bacteria. Since their recent discovery less than a decade ago, both TLRs and NLRs have been shown to be crucial in host protection against microbial infections but also in homeostasis of the colonizing microflora. They recognize specific microbial ligands and with the use of distinct adaptor molecules, they activate different signalling pathways that in turns trigger subsequent inflammatory and immune responses that allows a immediate response towards bacterial infections and the initiation of the long-lasting adaptive immunity.
In this review, we will focus on the role of the TLRs against bacterial infections in humans in contrast to mice that have been used extensively in experimental models of infections and discuss their role in controlling normal flora or nonpathogenic bacteria. We also highlight how bacteria can evade recognition by TLRs.
PMID: 17547708 [PubMed - in process]
What is the role of Toll-like receptors in bacterial infections?
Semin Immunol. 2007 Feb
Innate immunity relies on signalling by Toll-like receptors (TLRs) to alert the immune system of the presence of invading bacteria. TLR activation leads to the release of cytokines that allow for effective innate and adaptive immune responses. However, the contribution of different TLRs depends on the site of the infection and the pathogen. This review will describe the involvement of TLRs in the development of three different bacterial infections as well as our current understanding of the role of TLRs during microbial pathogenesis.Science Direct
Saturday, June 02, 2007
The Challenge of Treating Biofilm-associated Bacterial Infections
Clin Pharmacol Ther. 2007 May
Del Pozo JL, Patel R.
1Division of Infectious Diseases, Mayo Clinic, Rochester, Minnesota, USA.
Biofilm formation is a crucial step in the pathogenesis of many subacute and chronic bacterial infections, including foreign body-related infections. Biofilms are difficult to eradicate with conventional antimicrobial agents. Bacterial biofilms have several potential antimicrobial resistance mechanisms. Antimicrobial resistance mechanisms may act concurrently, and in some cases, synergistically. Persister cells play a major role in the tolerance of biofilm bacteria to antimicrobial agents. Understanding the mechanisms involved in biofilm-associated antimicrobial resistance is key to development of new therapeutic strategies.Clinical Pharmacology & Therapeutics advance online publication 30 May 2007. doi:10.1038/sj.clpt.6100247.
PMID: 17538551 [PubMed - as supplied by publisher]
Biofilms and antimicrobial resistance.
The pathogenesis of many orthopaedic infections is related to the presence of microorganisms in biofilms. I examine the emerging understanding of the mechanisms of biofilm-associated antimicrobial resistance. Biofilm-associated resistance to antimicrobial agents begins at the attachment phase and increases as the biofilm ages. A variety of reasons for the increased antimicrobial resistance of microorganisms in biofilms have been postulated and investigated. Although bacteria in biofilms are surrounded by an extracellular matrix that might physically restrict the diffusion of antimicrobial agents, this does not seem to be a predominant mechanism of biofilm-associated antimicrobial resistance.
Nutrient and oxygen depletion within the biofilm cause some bacteria to enter a nongrowing (ie, stationary) state, in which they are less susceptible to growth-dependent antimicrobial killing. A subpopulation of bacteria might differentiate into a phenotypically resistant state. Finally, some organisms in biofilms have been shown to express biofilm-specific antimicrobial resistance genes that are not required for biofilm formation.
Overall, the mechanism of biofilm-associated antimicrobial resistance seems to be multifactorial and may vary from organism to organism. Techniques that address biofilm susceptibility testing to antimicrobial agents may be necessary before antimicrobial regimens for orthopaedic prosthetic device-associated infections can be appropriately defined in research and clinical settings. Finally, a variety of approaches are being defined to overcome biofilm-associated antimicrobial resistance.