![]() ![]() The rates of penicillin and ceftriaxone resistant strains of Streptococcus pneumoniae are relatively low in adults. ![]() Community-acquired MRSA pneumonia can also occur and accounts for 3% of bacterial pneumonia cases, usually being associated with younger patients, post-influenza, and necrotizing pneumonia. While most community-acquired pneumonia (CAP) cases are caused by Streptococcus pneumoniae, health care associated pneumonias (HCAPs), particularly ventilator-associated pneumonia (VAP), are often caused by MRSA. The microbiology of pneumonia varies considerably based on the presence of risk factors for antibiotic resistance. In the ICU, respiratory tract infections especially pneumonia, represent the most common infection and carry the highest mortality. Given these newly described resistance patterns, testing for susceptibility and adequate antibiotic dosing are of paramount importance for proper management of critically ill infected patients.įor the purpose of this review we will focus on the contribution of GPC to infections in critically ill patients emphasizing the agents available for their treatment. New resistance patterns are also emerging to include vancomycin - intermediate Staphylococcus aureus (VISA), increases in the Staphylococcus aureus minimum inhibitory concentration (MIC) to vancomycin without breaching the resistance threshold (i.e., MIC creep), vancomycin-resistant Staphylococcus aureus (VRSA) due to acquisition of the vanA gene, as well as daptomycin and linezolid resistance. A recent survey showed that GPC cause the majority of nosocomial infections with Staphylococcus aureus (16%, with more than 50% being methicillin-resistant ) and Enterococcus species (14%, with vancomycin-resistant enterococci accounting for approximately 3.5% of all infections) predominating. The microbiology in the ICU has changed in the last 2 to 3 decades so that Gram-positive cocci (GPC) now represent one of the dominant species. The administration of early appropriate antibiotics is recognized as one of the most important interventions linked to improving patient outcomes in sepsis. Sepsis represents a major heath care problem with half of the cases occurring in the critically ill and it is associated with a high mortality (50% for septic shock) for intensive care unit (ICU) patients. Similarly, the expansion of VRE as a pathogen in the ICU setting has required the development of agents targeting this important pathogen. Although vancomycin has traditionally been considered a first-line therapy for serious MRSA infections, multiple concerns with this agent have opened the door for alternative agents demonstrating efficacy in this role. When initiating empiric antibiotics, it is of vital importance that this therapy be timely and appropriate, as delays in treatment are associated with adverse outcomes. The increasing range of these pathogens, such as the emergence of community-associated MRSA clones, emphasizes that all specialties of physicians treating infections should have a good understanding of the infections caused by Gram-positive bacteria in their area of practice. At present, it is important that clinicians recognize the changing resistance patterns and epidemiology of Gram-positive bacteria as these factors may impact patient outcomes. This has led to the development of a number of new antibiotics for the treatment of Gram-positive bacteria. Over the last three decades infections with these pathogens has increased as has their overall resistance to available antimicrobial agents. Gram-positive bacteria to include methicillin-resistant Staphylococcus aureus (MRSA), methicillin-susceptible Staphylococcus aureus (MSSA), and enterococci, to include vancomycin-resistant enterococci (VRE), display a remarkable array of resistance and virulence factors, which have contributed to their prominent role in infections of the critically ill. ![]()
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