The seven month study identified 53 cases of community-acquired pneumonia, or CAP, caused by the Staphylococcus aureus bacterium. This number is higher than expected based on anecdotal evidence and case studies. Lead researcher Alexander Kallen noted that case studies “tend to highlight the severest of cases and may present a biased picture.”

While CAP caused by staph may be more common than thought, the incidence of fatality may actually be lower than case studies suggested. Previously believed to be between 30% and 50%, the CDC study indicates a case-fatality rate of approximately 13%.

Methicillin-resistant Staphylococcus aureus, or MRSA, was responsible for just under half of the staph-related cases of CAP. The researchers discovered that nearly 40% of the pediatric patients with CAP caused by MRSA were given antibiotics that did not cover the resistant strain of staph. Medical professionals may not recognize MRSA as a significant cause of pneumonia during flu season, Alexander Kallen said.

Researchers indicated that further study is necessary to expand upon these preliminary results and build a more complete picture of this disease. The full findings of the study were presented on March 19 at the 2008 International Conference on Emerging Infectious Diseases.

The research supported by the National Institutes of Health revealed that squalene synthase inhibitors act as a sort of Kryptonite to Staphylococcus aureus bacteria by removing their natural defense: staphyloxanthin, a carotenoid pigment that gives staph a golden hue. S. aureus bacteria that lack that pigment have inhibited ability to fight off the human immune response, resulting in decreased virulence.

In studies, the squalene sythase inhibitor BPH-652 interfered with the enzyme responsible for producing the staphyloxanthin pigment. The resulting colorless staph bacteria were significantly weakened. Lab mice injected with S. aureus bacteria that also received BPH-652 exhibited a 98% reduction in bacterial counts.

Researchers are testing hundreds of additional compounds to determine if any are more effective in stripping staph bacteria of their color and virulence. The research is still in a very early stage – too early for human trials – but pigment reduction appears to be a promising area for further investigation.

The complete study results were reported in the article “A Cholesterol Biosynthesis Inhibitor Blocks Staphylococcus aureus Virulence” published in Science Express, the online edition of Science magazine.

Comparative genome sequencing methods were used by National Institute of Allergy and Infectious Diseases (NIAID) scientists to study the evolution of the USA300 group of CA-MRSA strains. Results showed that of 10 geographically diverse patient samples of USA300, the so-called “epidemic strain,” eight were virtually indistinguishable and two were more distantly related.

Researchers also noted that extremely small genetic differences found in evolving strains had a dramatic impact on drug-resistance and potential lethality in humans.

The study was led by Frank R. DeLeo, Ph.D., at NIAID’s Rocky Mountain Laboratories in Montana. “We anticipate that new USA300 derivatives will emerge within the next several years and that these strains will have a wide range of disease-causing potential,” said Dr. DeLeo, who noted the “extraordinary transmissibility and fitness” of the USA300 group of MRSA strains.

Dr. DeLeo and his colleagues hope this research will lead to the development of new diagnostic tests that can quickly identify individual strains of CA-MRSA.

The NIAID study will appear online this week in the Proceedings of the National Academy of Sciences.

More drug-resistant than the MRSA seen in schools and gyms, infections caused by this type of staph can be very serious, and even lethal when not treated appropriately. Like other staph infections, it spreads through casual contact, including sports and sexual activity. It often presents as an abscess or cellulitis in the buttocks, genitals, or perineum.

Gay male residents of San Francisco were 13 times more likely to have the infection than other residents of the city, according to a study published by the Annals of Internal Medicine on Monday. In Boston, up to half of gay men with staph infections are afflicted with the more drug-resistant strain, the study reported. Multidrug-resistant MRSA is also more prevalent in people with HIV.

This new variant of MRSA is so resistant to treatment by antibiotics that precious few options are available to medical practitioners. It is resistant to clindamycin, tetracycline, and mupirocin, as well as methicillin. It also causes more virulent infections that grow and spread rapidly.

The paper published in the Annals of Internal Medicine indicated that multidrug-resistant MRSA likely spread through sexual contact among the infected gay men that were studied. Spread of the multi-resistant staph among gay men was particularly associated with high risk behavior such as drug use and sex with multiple partners.

Researchers expressed a high degree of concern over the potential epidemic once multidrug-resistant MRSA spreads throughout the general population, cautioning that prevention is key. According to medical professionals, the best defenses against all types of staph infections are good hygiene and hand washing practices.

Another concern raised by the study is that multidrug-resistant MRSA may stigmatize gay men in much the same way that HIV/AIDS did in the 1980s. However, this pernicious superbug is not confined to gay males. For example, an 81-year-old woman in New York City was diagnosed with the infection, according to NPR’s All Things Considered program.

The full study, “Emergence of Multidrug-Resistant, Community-Associated, Methicillin-Resistant Staphylococcus aureus Clone USA300 in Men Who Have Sex with Men,” is currently available on the Annals of Internal Medicine Web site.

Light therapy may be the answer.

Current research in the area of photomedicine is poised to have a huge impact on how doctors respond to serious drug-resistant staph infections like methicillin-resistant Staphylococcus aureus, or MRSA. While antibiotics don’t always have the desired results, light therapy for MRSA-infected wounds is showing great promise, according to researchers at the Wellman Center for Photomedicine at Massachusetts General Hospital.

Therapeutic light is not new in the treatment of human ailments. Light therapy devices are successful at providing joint and muscle pain relief, and photodynamic therapies for cancer and dermatological conditions are currently under evaluation.

The light therapy wound treatments being studied at the Wellman Center could help reduce the high mortality rate of MRSA by providing faster cures without side effects. Estimates by the Centers for Disease Control indicate that MRSA kills more people than AIDS in the United States each year.

In animal tests performed by Wellman Center researchers, a deeply penetrating light focused on a wound colonized with MRSA was able to kill the bacteria in just 15 minutes. Treatment with antibiotic medicines takes days to weeks.

Light therapy for MRSA is also good news for patients concerned about the many side effects associated with traditional antibiotics. When focused on an infected wound, the light initiates chemical processes that are harmful to the bacteria, not the patient.

Wellman Center researchers will study the use of light therapy to treat MRSA infections in human populations next.

The APIC survey served as an informal six-month follow-up to the organization’s MRSA Prevalence Study released in June. The MRSA Prevalence Study indicated that MRSA was “significantly more widespread” than previously thought, with rates measuring eight times higher than earlier estimates.

The follow-up poll sought to gauge the impact of the MRSA Prevalence Study results on infection control measures in hospital settings. 41 percent of respondents said that their facility had not implemented any new prevention measures since June. Explanations indicated that “many infection prevention programs are still inadequately funded and that facilities lack resources, staff, and buy-in from senior management to prevent the transmission of MRSA, ” according to Kathy L. Warye, Chief Executive Officer of APIC.

APIC provides their membership with guidelines for implementing a MRSA transmission prevention program. Recommended components include risk assessment, surveillance, hand hygiene, contact precautions, proper housekeeping, and testing of new admissions and high risk groups. Controlling MRSA also requires the explicit support of hospital administrators, and a transformation of the facility’s culture, APIC guidelines suggest.