Some current issues in the pharmacokinetics/pharmacodynamics of antimicrobials in intensive care.

Infections, particularly those caused by resistant pathogens, are a common cause of morbidity and mortality in critically ill patients. However, the availability of effective antimicrobial agents is limited. Critical illness itself can influence the pharmacokinetic/pharmacodynamic (PK/PD) parameters of antimicrobials by altering their volume of distribution and the rate of their excretion and elimination and by impairing their penetration into tissues. Therefore, when designing a treatment regimen, the intensivist should consider and take advantage of antibiotic PK/PD properties. There is significant but inconclusive evidence that critically ill patients may benefit more when antibiotics with time-dependent action are administered in a continuous/prolonged infusion regimen. On the other hand, aminoglycosides exhibit a concentration-dependent pattern of killing and should be administered at high doses once daily or at extended intervals, and their levels in the plasma should by strictly monitored to avoid both underexposure and toxicity. The problem of antimicrobial resistance now involves agents traditionally considered reliable in that aspect, such as vancomycin. Strict monitoring of vancomycin MIC for methicillin-resistant Staphylococcus aureus and the prudent use of the available alternative agents as well as de-escalation strategies might be reasonable strategies for dealing with this problem.

Rifampicin combined regimens for gram-negative infections: data from the literature.

Multidrug-resistant (MDR) gram-negative bacterial infections are associated with high morbidity and mortality. Given the lack of availability of new highly effective antimicrobial drugs against multiresistant strains, combination regimens are administered that include rifampicin for its demonstrated in vitro synergism with multiple drugs. A literature review was performed of clinical studies reporting the use of rifampicin in the treatment of MDR gram-negative bacterial infections. Nineteen studies were found, including only one randomised controlled study. Data in the literature on combined therapeutic regimens with rifampicin are limited and refer mostly to uncontrolled studies. Therefore, the real clinical benefit of using rifampicin-containing therapies for the treatment of gram-negative multiresistant bacteria in terms of clinical outcome and survival rates still needs to be assessed.

The novel influenza A (H1N1) virus pandemic: An update.

In the 4 months since it was first recognized, the pandemic strain of a novel influenza A (H1N1) virus has spread to all continents and, after documentation of human-to-human transmission of the virus in at least three countries in two separate World Health Organization (WHO) regions, the pandemic alert was raised to level 6. The agent responsible for this pandemic, a swine-origin influenza A (H1N1) virus (S-OIV), is characterized by a unique combination of gene segments that has not previously been identified among human or swine influenza A viruses. As of 31th July 2009, 168 countries and overseas territories/communities have each reported at least one laboratory-confirmed case of pandemic H1N1 infection. There have been a total of 162,380 reported cases and 1154 associated deaths. Influenza epidemics usually take off in autumn, and it is important to prepare for an earlier start this season. Estimates from Europe indicate that 230 millions Europe inhabitants will have clinical signs and symptoms of S-OIV this autumn, and 7- 35% of the clinical cases will have a fatal outcome, which means that there will be 160,000- 750,000 H1N1-related deaths. A vaccine against H1N1 is expected to be the most effective tool for controlling influenza A (H1N1) infection in terms of reducing morbidity and mortality and limiting diffusion. However, there are several issues with regard to vaccine manufacture and approval, as well as production capacity, that remain unsettled. We searched the literature indexed in PubMed as well as the websites of major international health agencies to obtain the material presented in this update on the current S-OIV pandemic.

Surgical site infections in HIV-infected patients: results from an Italian prospective multicenter observational study.

BACKGROUND: The quality of life of the HIV-infected population in developed countries has substantially improved over the years. Accordingly, the clinical limitations in the surgical treatment of the HIV-infected patients are becoming fewer, and the number of HIV-infected patients undergoing surgical interventions of all types is increasing. However, available data on the incidence and risk factors for post-surgical complications, such as surgical site infections (SSI), in HIV-infected patients are still limited and often controversial. The aim of this study was to determine the incidence and the associated risk factors for SSI in HIV-infected patients. METHODS: A 1-year observational prospective multicenter surveillance study was conducted in 11 Italian Infectious Diseases Clinical Centers from which 305 consecutive HIV-infected patients undergoing different surgical procedures were enrolled. Postdischarge surveillance was conducted within 30 days after surgery. A number of variables were included in a multivariate analysis aimed at assessing potential risk factors for SSI, including body mass index, diabetes, Hepatitis C (HCV) and hepatitis B virus infection, lipodistrophy, HIV viral load, CD4 cell count and white blood cell count, preoperative hospital stay, National Nosocomial Infection Surveillance (NNIS) risk score, and any antimicrobial prophylaxis. RESULTS: SSI occurred in 29 of 305 (9.5%) patients, of which 17 (58.6%) SSI occurred during hospital stay, and 12 (41.4%) occurred during the postdischarge period. The SSI of the 29 patients were classified as superficial (21, 72.4%), deep (four, 13.8%), organ/space (one, 3.4%), and sepsis (three, 10.3%). Nearly 50% of the superficial and 50% of the deep SSI occurred during the postdischarge period. Organ/space infection and sepsis accounted for 13.7% of all SSI and were observed during the in-hospital stay. The multivariate analysis revealed that HCV co-infection was significantly associated to SSI occurrence. Total hospital stay was longer among patients with SSI than among those without SSI (p = 0.041). CONCLUSION: Although 92.5% of our HIV-infected patients presented a NNIS score < or = 1, the SSI rate was twofold higher than that reported in Italian and European studies for the general population, with more severe clinical presentations. This is the first report of an association between HCV-HIV co-infection and SSI occurrence. Additionally, the viro-immunological status of our patients was not related to SSI occurrence, which suggests the need for further research for other potential risk factors that may be implicated in the occurrence of SSI.

Bone marrow toxicity in HCV genotype 5a-infected patient after peg-IFN alpha-2a and ribavirin therapy.

The optimal therapy for HCV-related chronic hepatitis is the combination of pegylated interferon alpha (peg-IFN alpha) plus ribavirin (RBV). Unfortunately, both peg-IFN alpha and RBV are responsible for a wide range of adverse events and potentially severe toxicities, particularly hematological alterations. Indeed, RBV is generally responsible for anemia through hemolysis, while peg-IFN alpha induces more commonly leukopoenia and thrombocytopenia, presumably through bone marrow toxicity. Actually, data regarding histopathological bone marrow alterations in HCV-infected patients following IFN-alpha therapy is scanty. We report a case of a HCV-infected cirrhotic patient, who developed bone marrow alterations following one-year peg-IFN alpha plus RBV treatment, and we describe the associated histopathological features. Our case report provides new significant insight on the histopathological changes occurring in bone marrow of HCV-infected cirrhotic patients during peg-IFN alpha-2a plus RBV treatment, providing also additional information on potential bone marrow toxicity in the course of IFN-based treatments.

Increased hepatitis C virus (HCV)-specific CD4+CD25+ regulatory T lymphocytes and reduced HCV-specific CD4+ T cell response in HCV-infected patients with normal versus abnormal alanine aminotransferase levels.

CD4+CD25+ T regulatory cells may play a role in the different clinical presentations of chronic hepatitis C virus (HCV) infection by suppressing CD4+ T cell responses. Peripheral CD4+CD25+ T cells from chronic HCV carriers with normal and abnormal alanine aminotransferase (ALT) were analysed for specificity and effect on HCV-specific CD4+ T cell reactivity by flow cytometry for intracellular cytokine production and proliferation assay. HCV-specific CD4+CD25(+high) T cells consistently produced transforming growth factor (TGF)-beta but only limited amounts of interleukin (IL)-10 and no IL-2 and interferon (IFN)-gamma. The HCV-specific TGF-beta response by CD4+CD25(+high) T cells was significantly greater in patients with normal ALT compared to patients with elevated ALT. In addition, a significant inverse correlation was found between the HCV-specific TGF-beta response by CD4+CD25(+high) T cells and liver inflammation. In peripheral blood mononuclear cells (PBMC), both HCV antigen-induced IFN-gamma production and proliferation of CD4+ T cells were greater in patients with elevated ALT compared with patients with normal ALT. Depletion of CD4+CD25+ cells from PBMC resulted in an increase of both IFN-gamma production and proliferation of HCV-specific CD4+ T cells that was significantly greater in patients with normal ALT levels compared with patients with elevated ALT. In addition, CD4+CD25+ T cells from patients with normal ALT levels proved to be significantly more potent to suppress CD4+ T cell reactivity with respect to those from patients with elevated ALT. In conclusion, these data support the hypothesis that CD4+CD25+ cells may play a role in controlling chronic inflammatory response and hepatic damage in chronic HCV carriers.