Friday, January 04, 2013

 

Growth Factor: How Bacterial Infections Persist Through Antibiotics


Growth Factor: How Bacterial Infections Persist Through Antibiotics

By Katherine Harmon | Scientific American

Some strains of nasty bacterial infections, such as MRSA (methicillin-resistant Staphylococcus aureus), come loaded with resistance to antibiotics built right into their genes. But certain infections seem to acquire an ability to persist in the face of drugs that should knock them out--without developing the genetic hallmarks of antibiotic resistance. For decades, researchers have thought this holdout occurred because many antibiotics target cell growth, so even though most of the bacteria were killed by the drug, a select group simply shut down, going into a sort of hibernation, thereby allowing the infection to persist. In other words: if the bacteria aren't growing, they're also not dying.
But a new study suggests that quite the opposite is occurring: some surviving bacteria are actually flourishing and multiplying while under antibiotic attack. The findings were published online January 3 in Science.
"We thought that surviving bacteria made up a fixed population that stopped dividing," Neeraj Dhar, of the Swiss Federal Institute of Technology in Lausanne and study co-author, said in a prepared statement. Instead, a stable overall population was hiding a "very dynamic" colony, he said.
The researchers studied Mycobacterium smegmatis, a species closely related to the bacterium that causes tuberculosis (Mycobacterium tuberculosis), which often resists antibiotic treatment and remains a major health threat in many countries. The traditional analysis of a persistent culture of these bacteria would reveal that the population was not growing, which is what had led scientists to think that the colony had been reduced to non-proliferating "persister cells" that could better ride out the antibiotic attack by laying low. But using time-lapse images taken through a microscope of cells in a microfluidic culture (allowing study of small-scale changes), the researchers saw quite a different story.
"Using microfluidics, we can now observe every bacterium individually, instead of having to count a population," John McKinney, also of the Swiss Federal Institute of Technology, said in a prepared statement. Not only were the surviving cells not playing dead, they were just as likely to be growing as cells that died off.
McKinney and his team observed that even after the introduction of an antibiotic and the death of most bacterial cells, a large percentage of the so-called persister cells continuing to divide--129 of 153 progenitor cells they followed divided at least once in the face of antibiotic treatment. And this cycle of growth, division and death kept up for at least 10 days of exposure to the antibiotic.
The antibiotic was isoniazid (known by the drug names Laniazid and Nydrazid), which has been a common first-line treatment for tuberculosis. This antibiotic becomes an activated bacterium killer when it comes into contact with an enzyme called KatG that the bacteria produces. The enzyme, however, was not produced consistently, the researchers found. Instead, individual cells generated it in seemingly random spurts. So the cells that happened to have had pauses in their KatG production at just the right time were often able to avoid activating the antibiotic--and thus were saved from certain death.
Tuberculosis cells that should have been essentially identical, genetically, showed different propensities for survival, pointing to a possible role of epigenetic differences (such as those in gene expression) in determining cell survival. "This diversity is critical for microbial persistence in fluctuating environments because it ensures that some individuals may survive a lethal stress that would otherwise extinguish the population," the researchers explained in their paper.
Because cell survival does not seem to be tied to permanent genetic change in this case, it means the bacterial colony should remain susceptible to future antibiotic treatment, which could be good news for treating infections. However, given the low level of continued growth and change during exposure to antibiotics, "the bacteria can mutate and thus develop resistance in the presence of the antibiotic," Dhar said.
This discovery now paints a clearer picture of how antibiotic resistance can develop in persistent bacterial infections. With so many individual bacteria reproducing, "some of them can adapt to stressors that they have not previously encountered, thanks to the selection of persistent individuals," McKinney said. Such findings could help inform the creation of more effective antibiotics and perhaps expand to other illnesses, such as the persistence of cancer cells, although the researchers acknowledge that the persistence behavior of other bacterial infections might be quite different.
Nevertheless, the insights offer "a new approach for trying to figure out why some infections are so difficult to eliminate," McKinney said.

News Yahoo

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# posted by Pat O'Connor @ 7:31 AM

Thursday, October 25, 2012

 

Postoperative infections in obstetrics and gynecology.


Postoperative infections in obstetrics and gynecology.


Dec 2012

Jaiyeoba O.

Source

Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, South Carolina.

Abstract


Postoperative infection is the most commonly seen complication of surgery in obstetrics and gynecology. The use of antibiotic prophylaxis has greatly decreased though not completely eliminated this adverse outcome. Postoperative infections include wound cellulitis, wound abscess, endomyometritis, pelvic cellulitis, and pelvic abscess. Infections usually manifest as fever and greater than normal postoperative pain. Refractory fevers maybe because of septic pelvic vein thrombophlebitis or maybe noninfectious in origin. Broad-spectrum antibiotics should be initiated as soon as possible when diagnosis of postoperative infection is made; most patients will respond to treatment within 24 to 48 hours when appropriate antibiotics are selected.

Lippincott, Williams & Wilkins

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# posted by Pat O'Connor @ 7:52 AM

Saturday, September 01, 2012

 

Study: Tattoo infections traced to tainted ink


Study: Tattoo infections traced to tainted ink


August 2012

ATLANTA — An outbreak of infected tattoos has led to an unlikely source: the ink.
With the growing popularity of tattoos, health officials say they are seeing more cases of a nasty skin infection caused by a common bacteria traced to the ink. In the largest outbreak, 19 people in Rochester, N.Y., ended up with bubbly rashes on their new tattoos, researchers reported Wednesday.
Infections from tattooing are nothing new. Hepatitis, staph infections and even the superbug known as MRSA have been tied to tattoos. Dirty needles and unsanitary conditions are often to blame.
But all the New York cases were linked to an unidentified artist who wore disposable gloves and sterilized his instruments. The problem, investigators concluded, was in the ink.
"Even if you get a tattoo from a facility that does everything right, it's not risk free," said Dr. Byron Kennedy, deputy director of the health department in New York's Monroe County. He is lead author of a report on last fall's Rochester cases was released by the New England Journal of Medicine on Wednesday.
In the past year, there have been 22 confirmed cases and more than 30 suspected cases of the skin infection in Colorado, Iowa, New York and Washington state, health officials said. The infections were tied to ink or water used to dilute the ink. Tattoo artists and ink makers should use only sterile water to dilute ink, health officials advise.
Scattered reports of the illness in tattoo customers have been reported over the past 10 years. But they may be growing more common as more people get tattoos, experts said. An estimated 1 in 5 U.S. adults have at least one tattoo, an increase from years past, according to polls.
The illnesses were caused by a bacterial cousin of tuberculosis named Mycobacterium chelonae (pronounced chell-OH-nay). The bacteria can cause itchy and painful pus-filled blisters that can take months to clear up, and involve treatment with harsh antibiotics with unpleasant side effects.
The bacteria are common in tap water, and have been seen in the past when tattoo artists used contaminated water to lighten dark ink. The ink used in New York was "gray wash," used for shaded areas of tattoos. The ink was recalled and has not returned to the market.
Companies that make gray wash sometimes use distilled water to lighten the ink, thinking it's clean of infection-causing contaminants. But the bacteria can live in that too, said Tara MacCannell, who led a related investigation by the Centers for Disease Control and Prevention. Her study appears in CDC's Morbidity and Mortality Weekly Report released Wednesday.
Some ink manufacturers add witch hazel or an alcohol preservative to lower risk of certain viruses, but those additives don't kill off the hardy chelonae bacteria, she added.
Investigators found the bacteria in opened and unopened bottles of ink at the New York tattoo parlor. They did not find it in water at the shop, MacCannell said.
Health officials say tattoo customers should ask what kind of ink is being used and what measures are in place to prevent infections.
WSJ Online

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# posted by Pat O'Connor @ 9:41 AM

Sunday, February 12, 2012

 

Treatment of chlamydial infections.

Treatment of chlamydial infections.


Feb 2012

Hammerschlag MR, Kohlhoff SA.

Source

SUNY Downstate Medical Center, Division of Infectious Diseases, Department of Pediatrics , 450 Clarkson Avenue, Brooklyn, NY 11203-2098 , USA +1 718 270 3097 ; +1 718 270 1985 ; mhammerschlag@downstate.edu.

Abstract


KeyWords: antibiotics, chlamydia pneumoniae, chlamydia trachomatis, chlamydiae

Introduction:

Chlamydiae are obligate intracellular bacterial pathogens whose entry into mucosal epithelial cells is required for intracellular survival and subsequent growth. The life cycle of Chlamydia spp. and the ability to cause persistent, often subclinical infection, has major ramifications for diagnosis and treatment of C. trachomatis and C. pneumoniae infections in humans.


Areas covered:

This up-to-date review describes the current state of knowledge of antimicrobial susceptibilities and treatment of genital infections due to C. trachomatis and respiratory infections due to C. pneumoniae. Expert opinion: Chlamydiae are susceptible to antibiotics that interfere with DNA and protein synthesis, including tetracyclines, macrolides and quinolones, which are the compounds that have been most extensively studied and used for treatment of humaninfection. Treatment of individuals with C. trachomatis genital infection prevents sexual transmission and complications, including pelvic inflammatory disease. Treatment of pregnant women will prevent the transmission of infection to infants during delivery. The benefits of treatment of respiratory infections due to C. pneumoniae are more difficult to assess, primarily because of the lack of FDA-approved, specific diagnostic tests for detection of the organism in clinical samples. The majority of published studies have relied on serology for diagnosis, making it difficult to assess microbiologic efficacy.

Informa World

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# posted by Pat O'Connor @ 8:01 AM

Tuesday, September 29, 2009

 

Hidradenitis suppurativa

Hidradenitis suppurativa

Tidsskr Nor Laegeforen. 2009 May

Tolaas E, Knudsen CW, Sviland L, Tønseth KA.

Hudavdelingen, Haukeland universitetssykehus, 5021 Bergen. etolaas@broadpark.no

BACKGROUND: Hidradenitis suppurativa is a chronic inflammatory skin disease characterized by recurrent tender nodules and boils, usually in the armpits and groins. Draining fistulas and hypertrophic scarring are hallmarks of more severe disease. The objective of this article is to review the clinical presentation, diagnostic considerations and treatment of the disease.

MATERIAL AND METHODS: The article is based on a non-systematic literature search in PubMed, review of dermatology textbooks and the author's personal clinical experience.

RESULTS: Hidradenitis suppurativa, also known as acne inversa, is a follicular occlusion disease that can severely reduce quality of life. Staphylococci and other pathogenic bacteria frequently colonize the lesions, but the disease is not primarily a bacterial infection. Smoking and obesity can worsen disease activity. Moderate and severe disease is usually treated with excisional surgery. Antibiotics, often tetracyclines, are indicated for mild disease and as an adjunct to surgery in more severe disease. Antibiotics, however, are not curative. New treatment options, such as TNF-alpha inhibitors and zinc gluconate should still be considered experimental.

INTERPRETATION: Hidradenitis suppurativa is probably underdiagnosed. The disease is often recalcitrant to treatment. The effect of medical treatment is not supported by high quality evidence.

PubMed

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# posted by Pat O'Connor @ 3:48 AM

Sunday, September 20, 2009

 

Complications of Infective Endocarditis.

Complications of Infective Endocarditis.
Cardiovasc Hematol Disord Drug Targets. 2009 Sep

Mocchegiani R, Nataloni M.
Via Tommasi 5, 60124 Ancona, Italy. r_mocc@yahoo.it.

Infective endocarditis (IE) is a lethal disease if not promptly treated with antibiotics, either in association with surgery or not. The incidence of disease has not decreased over the last decades due to the change of risk conditions. Complications of IE may involve cardiac structures when the infection spreads within the heart, or extra cardiac ones when the cause is usually from embolic origin; they may also be due to medical treatment or to the septic condition itself. A variety of complications may occur in most of patients. The literature reports one complication of IE in 57%, two in 26% and three or more in about 14% of patients examined. The frequency of specific complications depends on variables as the infecting pathogen, duration of disease before therapy and type of treatment. However it is often difficult to assess the true incidence of complications because the published reviews in literature are frequently based on retrospective chart reviews and different diagnostic criteria are used. The decision over either indication or timing of surgery should be individualized and based on a multidisciplinary approach involving at least cardiologists and cardiac surgeons. Congestive heart failure (CHF) is the most important complication of IE, which has the greatest impact on prognosis. Periannular abscesses are a relatively common complication of IE (42% to 85% of cases during surgery or at autopsy respectively), associated with a higher morbidity and mortality. Systemic embolization occurs in 22% to 50% of cases; emboli may involve major arteries, mostly affecting the central nervous system, but also other organs. Splenic abscess is a rare complication of IE, due to direct seeding of spleen by an embolus or bacterial seeding of a bland infarction. Neurological complications develop in 20% to 40% of patients with IE and represent a dangerous subset of complications. Mycotic aneurysms are rare, resulting from diffusion of infection to the vessel wall. Actually the clinical profile, the best treatment (medical or surgical approach) and outcome of complicated IE are not well defined. Changing trends in aetiology of IE with emerging infections from Staphylococci, bacteria of the HACEK group and Fungi have resulted in an increased frequency of culture negative IE. Sepsis or persistent fever despite appropriate antimicrobial therapy, recurrent emboli, heart failure or new pathologic murmurs suggest haemodynamic impairment and/or infection extending beyond the valve leaflet or prosthetic valvular annulus. The course of the disease will consequently get worse with an increasing need of surgery. Patients who develop abscesses are more likely to undergo surgery than those who do not (84-91% vs 36%), and also their in-hospital mortality rate is higher (19% vs 11%). A prompt detection of complications often allows an earlier surgical treatment which represents the best way to improve the outcome. The introduction of molecular methods techniques has increased the ability to identify the causal agents of IE, mostly in cases of culture negative endocarditis. Echocardiography, mainly from transesophageal (TEE) approach, has significantly improved the evaluation of IE allowing to detect the specific signs of the disease as vegetations, abscesses, valve insufficiency, prosthetic valve dehiscence, fistulas. In our 3rd referral Hospital (Lancisi Heart Hospital, Ancona, Italy) we performed a follow-up (mean 8.26 years) of 15 patients with periannular complications associated with IE. The long term follow-up showed low mortality rate, high incidence of reintervention, improved New York Heart Association (NYHA) class in survivors and no changes of the lesions at the echocardiographic examination, suggesting that periannular complications have not significantly influenced the overall survival in our patients at the follow-up.

PMID: 19751182 [PubMed - as supplied by publisher]

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# posted by Pat O'Connor @ 12:30 PM

Sunday, March 23, 2008

 

The Management of Clostridium difficile Infection: Antibiotics, Probiotics and Other Strategies

The Management of Clostridium difficile Infection: Antibiotics, Probiotics and Other Strategies

J Chemother. 2008 Feb

Senok AC, Rotimi VO.

Clostridium difficile-associated disease remains an important nosocomial infection associated with significant morbidity and mortality. In recent years, there has been an upward trend in the incidence of this condition with continuing high rates of recurrent disease with available treatment regimens. In this article, we review the current literature on the management of C. difficile-associated disease (CDAD). The potential role for alternative therapeutic options for the treatment of CDAD, including the use of bacteriotherapy in the form of probiotics, immunotherapy and ion-exchange resins as well as new drugs under investigation is explored.

The evidence indicates a need for innovative approaches to the management of this condition. The combined use of antibiotic therapy and replacement of gut microbiota using probiotics remains promising and we suggest a multi-pronged approach in the management of this challenging infection.

Journal of Chemotherapy

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# posted by Pat O'Connor @ 12:31 AM

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