Archive for August, 2012

Vancomycin: a 50-something-year-old antibiotic we still don’t understand.

Cleve Clin J Med. 2011 Jul V.78  N.7  P.465-71.

Schilling A, Neuner E, Rehm SJ.

Department of Infectious Disease, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA.


Because a significant proportion of Staphylococcus aureus strains as well as most coagulase-negative staphylococci are resistant to penicillin and semisynthetic beta-lactam drugs, the need for vancomycin and related antibiotics has never been greater. Effective use of vancomycin requires knowledge of dosing parameters and selection of target trough levels appropriate to the specific infection and to the pathogen being treated. For clinicians, it is vital to remain up-to-date with evolving definitions for vancomycin susceptibility, with new interpretations of efficacy, and with information on toxicity.


August 28, 2012 at 9:24 pm

Clinical impact of a real-time PCR assay for rapid identification of staphylococcal bacteremia.

J Clin Microbiol. 2012 Jan V.50  N.1  P.127-33.

Frye AM, Baker CA, Rustvold DL, Heath KA, Hunt J, Leggett JE, Oethinger M.

Department of Pharmacy, Providence St. Vincent Medical Center, Portland, Oregon, USA.


The purpose of this study was to evaluate the impact of real-time PCR reporting both on timely identification of clustered Gram-positive cocci (GPC) in blood cultures and on appropriate antibiotic treatment. This retrospective, interventional cohort study evaluated inpatients with blood cultures positive for GPC in the pre-PCR (15 January 2009 to 14 January 2010) and post-PCR (15 January 2010 to 14 January 2011) periods. Post-PCR implementation, laboratory services completed batched PCR; results other than methicillin-resistant Staphylococcus aureus (MRSA) were reported in the electronic medical record without additional interventions. The assay’s sensitivity and specificity, time to identification of staphylococcal bacteremia, and clinically relevant outcomes, including time to optimal antibiotic therapy, were evaluated. Demographic information was also collected and analyzed. Sixty-eight and 58 patients with Staphylococcus aureus bacteremia from the pre- and post-PCR periods, respectively, met inclusion criteria. Similar numbers of consecutive patients with coagulase-negative staphylococci were analyzed for comparison. The time to identification was significantly reduced post-PCR implementation (mean, 13.2 h; 95% confidence interval [95% CI], 10.5 to 15.9 h; P < 0.0001). However, the time to optimal antibiotic therapy was not significantly reduced. We conclude that implementation of a PCR assay demonstrated the potential to improve appropriate antibiotic use based on clinically meaningful and statistically significant reductions in the time to microbiologic identification. However, in order to realize this potential benefit, processes must be optimized and additional interventions initiated to facilitate providers’ use of the PCR result.


August 28, 2012 at 9:23 pm

Epidemic of invasive pneumococcal disease, western Canada, 2005-2009.

Emerg Infect Dis. 2012 May  V.18 N.5  P.733-40.

Tyrrell GJ, Lovgren M, Ibrahim Q, Garg S, Chui L, Boone TJ, Mangan C, Patrick DM, Hoang L, Horsman GB, Van Caeseele P, Marrie TJ.

Provincial Laboratory for Public Health (Microbiology) Edmonton, Alberta, Canada.


In Canada before 2005, large outbreaks of pneumococcal disease, including invasive pneumococcal disease caused by serotype 5, were rare. Since then, an epidemic of serotype 5 invasive pneumococcal disease was reported: 52 cases during 2005, 393 during 2006, 457 during 2007, 104 during 2008, and 42 during in 2009. Of these 1,048 cases, 1,043 (99.5%) occurred in the western provinces of Canada. Median patient age was 41 years, and most (659 [59.3%]) patients were male. Most frequently representing serotype 5 cases (compared with a subset of persons with non-serotype 5 cases) were persons who were of First Nations heritage or homeless. Restriction fragment-length polymorphism typing indicated that the epidemic was caused by a single clone, which multilocus sequence typing identified as sequence type 289. Large pneumococcal epidemics might go unrecognized without surveillance programs to document fluctuations in serotype prevalence.


August 28, 2012 at 9:22 pm

Pneumonia in healthy Canadian children and youth: Practice points for management.

Paediatr Child Health. 2011 Aug  V.16 N.7  P.417-24.

Le Saux N, Robinson J.


Although immunization has decreased the incidence of bacterial pneumonia in vaccinated children, pneumonia remains common in healthy children. Unless it is totally impractical, a chest radiograph should be performed to confirm the diagnosis of pneumonia. Factors such as age, vital signs and other measures of illness severity are critical in the decision regarding whether to admit a patient to hospital. Because Streptococcus pneumoniae continues to be the most common cause of bacterial pneumonia in children, prescribing amoxicillin or ampicillin for seven to 10 days remains the mainstay of empirical therapy for non-severe pneumonia. If improvement does not occur, consideration should be given to searching for complications (empyema or lung abscess). Routine chest radiographs at the end of therapy are not recommended unless clinically indicated.


August 27, 2012 at 8:28 am

Streptococcus pneumoniae serotype 19A in Latin America and the Caribbean: a systematic review and meta-analysis, 1990-2010.

BMC Infect Dis. 2012 May 28  V.12  N.1  P.124.

Castañeda E, Agudelo CI, De Antonio R, Rosselli D, Calderón C, Ortega-Barria E, Colindres RE.



Pneumococcal conjugate vaccines (PCVs) are in the process of implementation in Latin America. Experience in developed countries has shown that they reduce the incidence of invasive and non-invasive disease. However, there is evidence that the introduction of PCVs in universal mass vaccination programs, combined with inappropriate and extensive use of antibiotics, could be associated to changes in non-PCV serotypes, including serotype 19A. We conducted a systematic review to determine the distribution of serotype 19A, burden of pneumococcal disease and antibiotic resistance in the region.


We performed a systematic review of serotype 19A data from observational and randomized clinical studies in the region, conducted between 1990 and 2010, for children under 6 years. Pooled prevalence estimates from surveillance activities with confidence intervals were calculated.


We included 100 studies in 22 countries and extracted data from 63. These data reported 19733 serotyped invasive pneumococcal isolates, 3.8% of which were serotype 19A. Serotype 19A isolates were responsible for 2.4% acute otitis media episodes, and accounted for 4.1% and 4.4% of 4,380 nasopharyngeal isolates from healthy children and in hospitalbased/ sick children, respectively. This serotype was stable over the twenty years of surveillance in the region. A total of 53.7% Spn19A isolates from meningitis cases and only 14% from non meningitis were resistant to penicillin.


Before widespread PCV implementation in this region, serotype 19A was responsible for a relatively small number of pneumococcal disease cases. With increased use of PCVs and a greater number of serotypes included, monitoring S. pneumoniae serotype distribution will be essential for understanding the epidemiology of pneumococcal disease.


August 27, 2012 at 8:26 am

Glycopeptide resistance in gram-positive cocci: a review.

Interdiscip Perspect Infect Dis. 2012 

Sujatha S, Praharaj I.

Department of Microbiology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry 605006, India.


Vancomycin-resistant enterococci (VRE) have emerged as important nosocomial pathogens in the past two decades all over the world and have seriously limited the choices available to clinicians for treating infections caused by these agents. Methicillin-resistant Staphylococcus aureus, perhaps the most notorious among the nosocomial pathogens, was till recently susceptible to vancomycin and the other glycopeptides. Emergence of vancomycin nonsusceptible strains of S. aureus has led to a worrisome scenario where the options available for treating serious infections due to these organisms are very limited and not well evaluated. Vancomycin resistance in clinically significant isolates of coagulase-negative staphylococci is also on the rise in many setups. This paper aims to highlight the genetic basis of vancomycin resistance in Enterococcus species and S. aureus. It also focuses on important considerations in detection of vancomycin resistance in these gram-positive bacteria. The problem of glycopeptide resistance in clinical isolates of coagulase-negative staphylococci and the phenomenon of vancomycin tolerance seen in some strains of Streptococcus pneumoniae has also been discussed. Finally, therapeutic options available and being developed against these pathogens have also found a mention.



August 27, 2012 at 8:23 am

Should surgeons scrub with chlorhexidine or iodine prior to surgery?

Interact Cardiovasc Thorac Surg. 2011 Jun;12(6):1017-21.

Jarral OA, McCormack DJ, Ibrahim S, Shipolini AR.

Department of Cardiothoracic Surgery, The London Chest Hospital, Bonner Road, London E2 9JX, UK.


A best evidence topic was written according to a structured protocol. The question addressed was whether chlorhexidine gluconate is equivalent or superior to the use of povidone-iodine during surgical hand scrub. A total of 593 papers were found using the reported searches of which eight represented the best evidence to answer the clinical question. The authors, date, journal, study type, population, main outcome measures and results are tabulated. We conclude that whilst both chlorhexidine and povidone-iodine reduce bacterial count after scrubbing, the effect of chlorhexidine is both more profound and longer lasting. The studies found analysed the difference in reduction in colony forming units or bacterial count following surgical scrub in order to conclude that chlorhexidine was superior. Four studies went further to analyse cumulative and residual activity by testing for bacterial reduction after using a scrub solution for a number of days, an area in which chlorhexidine showed consistent advantages over povidone-iodine. These findings are given more credibility by the clinical finding of a recent meta-analysis of over 5000 patients in which chlorhexidine as an antiseptic skin preparation was associated with significantly reduced surgical site infection (SSI) in clean-contaminated surgery. Despite this, there is no evidence suggesting the use of chlorhexidine during hand scrub reduces SSI, which perhaps explains why guidelines from the World Health Organization, the Centers for Disease Control and Prevention and the Association for Perioperative Practice do not recommend one specific antimicrobial over another for hand scrub.


August 27, 2012 at 8:21 am

Effect of serotype on focus and mortality of invasive pneumococcal disease: coverage of different vaccines and insight into non-vaccine serotypes.

PLoS One. 2012  V.7  N.7   e39150.

van Hoek AJ, Andrews N, Waight PA, George R, Miller E.

Immunisation, Hepatitis and Blood Safety Department, Health Protection Agency, London, United Kingdom.



Differences in pathogenicity between pneumococcal serotypes are important when assessing the potential benefit of different valency vaccines. We investigated the effect of serotype on clinical presentation, outcome, and quality of life lost from invasive pneumococcal disease (IPD) in the context of the 7, 10, and 13 valent pneumococcal conjugate vaccines (PCV7, PCV10, PCV13).


Serotyped IPD cases in England were linked to the national dataset of hospital admissions for April 2002 to March 2011. Based on patients’ diagnostic codes and vital status at the end of the admission, disease focus (meningitis, empyema, sepsis, or respiratory disease) and case fatality rates by serotype and age group (5, 5-64, and 65 years and over) were obtained. Using these data the quality adjusted life years (QALY) lost from the IPD remaining when use of PCV7 stopped in 2010 was estimated for the serotypes covered by higher valency vaccines.


The linked dataset contained 23,688 cases with information on diagnosis, mortality, and serotype. There were significant differences between serotypes in the propensity to cause meningitis, death, and QALY loss in each of the investigated age groups. As a result, vaccines’ coverage of disease burden differed by endpoint. For example, in children under 5 years in 2009/10, PCV10 covered 39% of meningitis, 19% of deaths and 28% of the QALY loss of attributable to IPD, whereas the respective percentages for PCV13 were 65%, 67%, and 66%. The highest QALY loss per serotype in this age group was for 6A. Non-PCV serotypes causing the highest QALY loss were 22F and 33F in <5 year olds and 31 in older individuals.


Marked differences exist between serotypes in clinical presentation and outcome, and these should be considered when evaluating the potential impact of higher valency vaccines on overall disease burden and associated QALY loss.


August 26, 2012 at 11:13 am

Infectious disease trends among immunocompromised hosts.

Singapore Med J. 2012 Apr  V.53 N.4  P.223-9.

Young B, Tambyah PA.

Communicable Diseases Centre, Tan Tock Seng Hospital, Singapore.


With our rapidly ageing population and advancing treatments for patients with haematological, oncologic and rheumatological diseases, there are increasing numbers of immunocompromised patients presenting to primary care and general hospitals with opportunistic infections. This review considers the trends of these infections across four representative subgroups: fungal infections following haematopoietic stem cell transplant; viral infections post solid organ transplant; mycobacterial infections during treatment with targeted biological agents; and bacterial infections as a cause of fever in neutropenia. We also consider the impact of host, pathogens, environments and treatments on the epidemiology and outcomes of these infections.


August 25, 2012 at 2:49 pm

Current concepts in antimicrobial therapy against select gram-positive organisms: methicillin-resistant Staphylococcus aureus, penicillin-resistant pneumococci, and vancomycin-resistant enterococci.

Mayo Clin Proc. 2011 Dec  V.86 N.12  P.1230-43.

Rivera AM, Boucher HW.

Division of Geographic Medicine and Infectious Diseases, Tufts Medical Center, Boston, MA 02111, USA.


Gram-positive bacteria cause a broad spectrum of disease in immunocompetent and immunocompromised hosts. Despite increasing knowledge about resistance transmission patterns and new antibiotics, these organisms continue to cause significant morbidity and mortality, especially in the health care setting. Methicillin-resistant Staphylococcus aureus poses major problems worldwide as a cause of nosocomial infection and has emerged as a cause of community-acquired infections. This change in epidemiology affects choices of empirical antibiotics for skin and skin-structure infections and community-acquired pneumonia in many settings. Throughout the world, the treatment of community-acquired pneumonia and other respiratory tract infections caused by penicillin-resistant Streptococcus pneumoniae has been complicated by resistance to β-lactam and macrolide antibacterial drugs. Vancomycin-resistant enterococci are a major cause of infection in the hospital setting and remain resistant to treatment with most standard antibiotics. Treatment of diseases caused by resistant gram-positive bacteria requires appropriate use of available antibiotics and stewardship to prolong their effectiveness. In addition, appropriate and aggressive infection control efforts are vital to help prevent the spread of resistant pathogens.



August 25, 2012 at 2:46 pm

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