The impact of early adequate antimicrobial therapy on 14-day mortality in patients with monomicrobial Pseudomonas aeruginosa and Acinetobacter baumannii bacteremia

The impact of colistin therapy for early adequate antimicrobial therapy on clinical outcomes has rarely been evaluated in patients with Pseudomonas aeruginosa bacteremia (PAB) or Acinetobacter baumannii bacteremia (ABB). We investigated the impact of early adequate antimicrobial therapy on 14-day mortality in 149 patients with monomicrobial PAB and ABB at two medical centers where colistin treatment was frequently used. Patients who survived the first 14 days of PAB/ABB received adequate antimicrobial therapy within 3 days of bacteremia more frequently than those who died (53.3 vs. 38.6 %), although this finding is not statistically significant (p = 0.10). After excluding patients who received adequate colistin therapy, the difference was statistically significant (94.6 vs. 58.8 %, p = 0.001). In a multiple regression model excluding patients who received colistin therapy, adequate antimicrobial therapy within 3 days of bacteremia was a preventive factor for 14-day mortality (adjusted OR = 0.23, 95 % CI = 0.07–0.80, p = 0.02). In another multiple regression model including patients who received colistin, compared to inadequate antimicrobial therapy, adequate non-colistin therapy was a preventive factor for 14-day mortality (aOR = 0.22, 95 % CI = 0.07–0.78, p = 0.019), but adequate colistin therapy was not (aOR = 8.20, 95 % CI = 1.07–62.90, p = 0.043). The favorable impact of early adequate antimicrobial therapy on 14-day mortality in patients with monomicrobial PAB/ABB may be lessened in the clinical practice of using colistin frequently. Further studies may be needed to evaluate the clinical impact of colistin therapy in patients with PAB or ABB.     

Performance of cobas® 4800 and m2000 real-time™ assays for detection of Chlamydia trachomatis and Neisseria gonorrhoeae in rectal and self-collected vaginal specimen

A prospective, multicenter trial was designed to compare the performance characteristics of the cobas® 4800 (Roche Diagnostics, Indianapolis, IN, USA) and m2000 real-time™ (Abbott Molecular Inc., Des Plaines, IL, USA) assays for detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) in rectal and self-collected vaginal swabs. Rectal (n = 234) or self-collected vaginal swabs (n = 687) were obtained from consenting individuals visiting their general practitioners, dermatologists, gynecologists, sexually transmitted disease clinics, or family planning centers from May 2010 to February 2011. High concordance rates (≥96%) were observed between the cobas® 4800 and m2000 real-time™ assays for CT/NG detection in both rectal and self-collected vaginal swabs. The performance profiles confirm the usefulness of both kinds of swab types for CT and NG detection using described nucleic acid amplification tests assays. Based on this study, rectal and self-collected vaginal swabs offer a noninvasive alternative, which may improve screening for CT and NG infections.     

Pathogenesis and prevention of immune reconstitution disease during antiretroviral therapy

A long-held doctrine is that bactericidal antibiotics are required for infections in neutropenic patients. We evaluated the available published evidence regarding the role of linezolid, a bacteriostatic antibiotic, in neutropenic patients with Gram-positive infection. We retrieved two prospective comparative studies (one of them a double-blind, randomized, controlled trial), a prospective cohort study, two retrospective studies and eight case reports that focused on the use of linezolid for Gram-positive bacterial infections in neutropenic patients. Linezolid was administered to 438 neutropenic patients, mainly on a compassionate-use basis, as other antibiotics failed to cure the infection or were associated with significant adverse events. The clinical cure rate ranged between 57 and 87.3% in the intention-to-treat population of the prospective studies. In total, 56 out of 438 (12.7%) neutropenic patients that received linezolid died during therapy. In the only randomized controlled trial that compared linezolid with vancomycin in the treatment of Gram-positive infections in neutropenic patients, mortality was 5.6 versus 7.6%, respectively (p = 0.4). In conclusion, the available evidence suggests that linezolid may be successful in a significant proportion of neutropenic patients with infection, despite the fact that it is a bacteriostatic agent. Such data seem to justify further studies regarding the role of linezolid in this patient population.     

Therapeutic utility of antibacterial peptides in wound healing

Cationic antimicrobial peptides were first thought to fight infection in animal models by disintegrating bacterial peptides and later by inhibiting bacteria-specific intracellular processes. However, ever increasing evidences indicate that cationic peptides accumulate around and modulate the immune system both systemically and in cutaneous and mucosal surfaces where injuries and infections occur. Native and designer antibacterial peptides as well as cationic peptides, never considered as antibiotics, promote wound healing at every step of cutaneous tissue regeneration. This article provides an introductory list of examples of how cationic peptides are involved in immunostimulation and epithelial tissue repair, eliminating wound infections and promoting wound healing in potential therapeutic utility in sight. Although a few antimicrobial peptides reached the Phase II clinical trial stage, toxicity concerns limit the potential administration routes. Resistance induction to both microbiology actions and the integrity of the innate immune system has to be carefully monitored.     

PCR for detection of respiratory viruses: seasonal variations of virus infections

Real-time PCR and related methods have revolutionized the laboratory diagnosis of viral respiratory infections because of their high detection sensitivity, rapidness and potential for simultaneous detection of 15 or more respiratory agents. Results from studies with this diagnostic modality have significantly expanded our knowledge about the seasonality of viral respiratory diseases, pinpointed the difficulties to make a reliable etiologic diagnosis without the aid of an unbiased multiplex molecular assay for respiratory viruses, and revealed previously unknown details as to possible infections with multiple agents as aggravating factors. The scope of this article is to review and discuss this new knowledge and its implications for diagnostic strategies and other measures essential for the clinical management of respiratory viral infections and for epidemiological surveillance of seasonal respiratory infections.