Archive for June 9, 2012

National guidelines for decolonization of methicillin-resistant Staphylococcus aureus carriers: the implications of recent experience in the Netherlands

Journal of Antimicrobial Chemotherapy   Oct  2011 V.67  N.10  P.2195-2198

Evelina Tacconelli1,* and Alan P. Johnson2

1Department of Infectious Disease, Università Cattolica, largo F. Vito 1, 00168, Rome, Italy

2Department of Healthcare-associated Infections and Antimicrobial Resistance, Health Protection Agency Centre for Infections, London NW9 5EQ, UK

Screening of patients for carriage of methicillin-resistant Staphylococcus aureus (MRSA) coupled with interventions such as contact isolation is widely regarded as a means of reducing rates of MRSA infection and inter-patient transmission. Recent studies in the Netherlands have shown that introduction of a national guideline in which uncomplicated carriage is treated with mupirocin nasal ointment and chlorhexidine soap solution, and complicated carriage is treated using the same regimen supplemented with two oral antibiotics, was successful, with up to 80% of patients being decolonized. Increased success was seen in patients, particularly those with complicated carriage, whose treatment adhered closely to the guideline. As the Netherlands has a low level of MRSA, further work is required to see if this regimen will be as effective at reducing carriage in countries with higher rates of endemic MRSA, where re-colonization may be expected to occur more often.


June 9, 2012 at 9:36 pm

Severity of pneumococcal pneumonia associated with genomic bacterial load.

Chest. Feb 2009  V.136 N.3 P.832-40.

Rello J, Lisboa T, Lujan M, Gallego M, Kee C, Kay I, Lopez D, Waterer GW; DNA-Neumococo Study Group.

Critical Care Department, Hospital Universitari Joan XXIII, 43007 Tarragona, Spain.



There is a clinical need for more objective methods of identifying patients at risk for septic shock and poorer outcomes among those with community-acquired pneumonia (CAP). As viral load is useful in viral infections, we hypothesized that bacterial load may be associated with outcomes in patients with pneumococcal pneumonia.


Quantification of Streptococcus pneumoniae DNA level by real-time polymerase chain reaction (rt-PCR) was prospectively conducted on whole-blood samples from a cohort of 353 patients who were displaying CAP symptoms upon their admission to the ED.


CAP caused by S pneumoniae was documented in 93 patients (36.5% with positive blood culture findings). A positive S pneumoniae rt-PCR assay finding was associated with a statistically significant higher mortality (odds ratio [OR], 7.08), risk for shock (OR, 6.29), and the need for mechanical ventilation (MV) [OR, 7.96]. Logistic regression, adjusted for age, sex, comorbidities, and pneumonia severity index class, revealed bacterial load as independently associated with septic shock (adjusted odds ratio [aOR], 2.42; 95% CI, 1.10 to 5.80) and the need for MV (aOR, 2.71; 95% CI, 1.17 to 6.27). An S pneumoniae bacterial load of >or= 10(3) copies per milliliter occurred in 29.0% of patients (27 of 93 patients; 95% CI, 20.8 to 38.9%) being associated with a statistically significant higher risk for septic shock (OR, 8.00), the need for MV (OR, 10.50), and hospital mortality (OR, 5.43).


In patients with pneumococcal pneumonia, bacterial load is associated with the likelihood of death, the risk of septic shock, and the need for MV. High genomic bacterial load for S pneumoniae may be a useful tool for severity assessment.


June 9, 2012 at 9:33 pm

Population structure, virulence factors and resistance determinants of invasive, non-invasive and colonizing Streptococcus agalactiae in Poland.

J Antimicrob Chemother. Sept 2010 V.65 N.9 P.1907-14.

Sadowy E, Matynia B, Hryniewicz W.

National Medicines Institute, ul Chełmska 30/34, 00-725 Warsaw, Poland.



To analyse Streptococcus agalactiae (group B Streptococcus; GBS) isolates collected in Poland from various human infections and carriage in respect of their clonality, distribution of virulence factors and antimicrobial resistance determinants, including the detection of transposons involved in the dissemination of antimicrobial resistance.


One hundred and fourteen GBS isolates were analysed by multilocus sequence typing (MLST), serotyping and detection of alp genes of the alpha-like-protein (Alp) family. Determinants of resistance to macrolides and tetracycline, and associated transposons, were detected by PCR and analysed by sequencing.


GBS isolates represented 30 different sequence types (STs), grouped in four clonal complexes (CCs), and belonged to seven serotypes. Serotype III was predominant (36.0%), followed by Ia, V, Ib, II, IV and VI. The most common alp genes were rib (26.3%) and alp1/alp5 (23.7%). The bac gene encoding the beta-compound of the surface C-protein was present in 17.5% of isolates. Erythromycin resistance (18.4% of isolates) was found in all CCs, but was associated with serotype V and ST1. The most prevalent determinant of resistance was erm(B), usually located on the Tn3872-like transposon. Several changes were observed in the regulatory region of erm(B), some of them resulting in elevated ketolide MICs. Resistance to tetracycline was ubiquitous (91.2%) and its most common determinant was tet(M), occurring in several variants that were typically carried on Tn916-family transposons.


Analysis of bacterial serotypes, alp genes and antimicrobial resistance determinants in the background of MLST-based population structure strengthened evidence of the importance of horizontal gene transfer in GBS evolution.


June 9, 2012 at 9:30 pm

A superficial swab culture is useful for microbiologic diagnosis in acute prosthetic joint infections.

Clin Orthop Relat Res. Feb 2009 V.467 N.2 P.531-5.

Cuñé J, Soriano A, Martínez JC, García S, Mensa J.

Department of Orthopaedic Surgery and Traumatology, Hospital Clínic of Barcelona, C/Villarroel 170, 08036, Barcelona, Catalonia, Spain.


The literature documents poor concordance between superficial swab and intraoperative tissue cultures in chronic prosthetic joint infections but is less clear in acute postsurgical prosthetic joint infections. We evaluated the relationship between superficial swab and deep intraoperative cultures in 56 patients with acute postsurgical prosthetic joint infections from June 2003 to June 2007; patients receiving antibiotics were excluded. There were 30 hip and 26 knee prostheses. A superficial sample of the wound drainage was taken at admission and three deep samples were obtained during open débridement. Concordance was defined when at least one of the microorganisms isolated in the superficial samples also was found in the deep samples. The analysis also was performed according to the type of microorganism: Staphylococcus aureus, gram-negative bacilli, or other gram-positive microorganisms. Concordance between superficial and deep samples was 80.3% (45 of 56). The sensitivity, specificity, and positive and negative predictive values of superficial cultures to predict the microorganism isolated in deep cultures varied depending on the type of microorganism: 93.7%, 100%, 100%, and 97.5% for S. aureus; 90%, 91.6%, 85.7%, and 94.3% for gram-negative bacilli; and 50%, 75%, 60%, and 66.7% for other gram-positive microorganisms. We therefore believe the superficial swab culture is useful in identifying the etiologic microorganism of acute prosthetic joint infections, especially when S. aureus or gram-negative bacilli were identified. Level of Evidence: Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.



June 9, 2012 at 9:27 pm


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