Physician's Weekly Article - Conference Highlights: The ICAAC/IDSA 2008 Annual Meeting

       The Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) and the Infectious Diseases Society of America (IDSA), held its 2008 annual meeting from October 25th to October 28th in Washington, DC. The features below highlight just some of the news emerging from the meeting. For more information on these items and other research that was presented, go to www.icaacidsa2008.org/

      Acute Pneumonia Associated With MI

      The Particulars: Research has shown that inflammation resulting from infection plays a critical role in the progression of coronary heart disease. Acute pneumonia causes a significant inflammatory response in patients which thereby may increase inflammation in atherosclerotic lesions of coronary arteries. A retrospective study was conducted in which the association between acute pneumonia and myocardial infarction (MI) was evaluated.

      Data Breakdown: Medical records of 206 patients who were hospitalized for pneumonia due to Streptococcus pneumoniae or Haemophilus influenzae were compared with a control group of patients admitted for other reasons in order to evaluate the incidence of MI. Patients with pneumonia were eight times more likely than the control group to suffer an MI 15 days after being admitted to the hospital. The risk of suffering an MI during the first 15 days after a pneumonia diagnosis was increased 45-fold in each individual patient 1 year preceding and 1 year following the pneumonia infection.

      Take Home Pearl: Future studies are necessary to clarify the biologic mechanisms underlying the association between pneumonia and MI in order to identify patients at highest risk for suffering a cardiac event following acute pneumonia.

      Sinusitis Commonly Caused by MRSA

      The Particulars: Bacterial sinusitis is a common infection typically treated with antibiotics, such as penicillins, cephalosporins, macrolides, and fluoroquinolones. However, these therapies are often ineffective against MRSA. Researchers evaluated the role of MRSA in acute and chronic sinusitis.

      Data Breakdown: Cultures were obtained from 215 patients between 2001 and 2003 and 243 patients between 2004 and 2006. S aureus was found in 8% of patients with acute sinusitis between 2001 and 2003, and 30% of these were attributed to MRSA. S aureus was recovered from 10% of patients with acute sinusitis between 2004 and 2006, and 69% of these were attributed to MRSA. S. aureus was found in 16% of patients with chronic sinusitis between 2001 and 2003; 27% were attributed MRSA. Between 2004 and 2006, S aureus was recovered from 20% of the patients with chronic sinusitis, and 61% were attributed to MRSA. MRSA was isolated in 23% of patients with chronic sinusitis who were administered antibiotics, compared with an 11% rate in those not previously treated.

      Take Home Pearls: A significantly higher rate of MRSA occurred in patients with acute and chronic maxillary sinusitis between 2004 and 2006 as compared with 2001 through 2003. Previous use of antimicrobial therapy was associated with increased isolation of MRSA. Obtaining endoscopic sinus cultures in patients with sinusitis—particularly in those who have failed to respond to antibiotic therapy—may guide physicians in selecting appropriate antibiotic treatments.

      Improving the Treatment of Bacterial Infections

      The Particulars: MRSA infections are considered to be optimally treated with a broad spectrum of antibiotics. However, methicillin-susceptible strains are typically best treated with narrow-spectrum antibiotics. Current tests that determine drug susceptibility or resistance to S aureus typically take 2 to 3 days before results can be determined. This can lead to physicians overprescribing broad-spectrum antibiotics or underprescribing narrow-spectrum antibiotics.

      Data Breakdown: The MicroPhage test (MicroPhage, Inc.) is a 5-hour test that has been shown in studies to accurately identify S aureus in blood cultures. It can also determine whether or not S aureus is methicillin resistance or methicillin susceptible. Bacteriophage amplification technology is used to detect an S aureus host in a sample. In a test of 120 S aureus clinical isolates and 120 closely related non-pathogenic coagulase-negative Staphylococci, the MicroPhage test demonstrated a sensitivity of 93% and a specificity of 96%. Among the strains identified as S aureus, methicillin susceptibility was determined with 99% sensitivity and 99% specificity.

      Take Home Pearl: The MicroPhage test appears to be an important tool in aiding the diagnosis and treatment of S aureus bacteremia.

      Do Dental Procedures Impact Artificial Joints?

      The Particulars: Artificial joint replacement surgery is increasingly performed in patients with underlying arthritis. Antibiotic use for some dental procedures has been recommended in selected patients with joint arthroplasty. Investigators evaluated the risk of prosthetic joint infection due to dental procedures and the role of antibiotic prophylaxis.

      Data Breakdown: A total of 678 patients were enrolled in a prospective, single-center, case-control study. Half of the patients were hospitalized with an artificial hip or knee infection and half were hospitalized with an artificial hip or knee arthroplasty that was not infected. No increased risk of artificial hip or knee infection was found in patients undergoing high- or low-risk dental procedures who were not administered antibiotic prophylaxis as compared with patients who did not undergo a dental procedure. Antibiotic prophylaxis in high- or low-risk dental procedures did not appear to decrease the risk of subsequent artificial hip or knee infection.

      Take Home Pearls: Dental procedures were not risk factors for subsequent total hip or knee infection. However, the use of antibiotic prophylaxis in patients with a joint arthroplasty should be reevaluated.

      The Consequences of Hand Washing Noncompliance

      The Particulars: Hand hygiene is recognized as the most important modifiable cause of hospital-acquired infections, yet hand hygiene compliance among healthcare workers has been estimated at only 45%. Poor compliance with hand hygiene can result in extended hospital stays and may increase expenses incurred by hospitals. A study was performed using a computer model simulation to determine the impact of improved hand washing compliance.

      Data Breakdown: A computer model simulation that used published data on MRSA prevalence, transmission, and cost was run one million times. The expected cost of an episode of hand washing noncompliance with respect to MRSA transmission was determined. Investigators found that each incident of hand washing noncompliance by a healthcare worker cost the hospital $1.98. This translated into a total cost of $1.77 million each year for a 200-bed hospital.

      Take Home Pearl: A 1% improvement in hand washing compliance was predicted to result in more than $39,000 in annual savings to hospitals.