Determinants of Staphylococcus aureus nasal carriage.

Nasal carriage of Staphylococcus aureus has been identified as a risk factor for community-acquired and nosocomial infections. We screened 230 donors of diverse ethnic and socioeconomic backgrounds and identified 62 (27%) whose nasal secretions were colonized by S. aureus. In 18 donors in whom the various regions of the nasal luminal surface were separately sampled, the predominant region of S. aureus colonization was the moist squamous epithelium on the septum adjacent to the nasal ostium. Nasal fluid from carriers was defective in killing endogenous S. aureus and nasal carrier isolates of S. aureus but not a laboratory S. aureus strain. Transmission electron microscopy revealed that S. aureus isolates incubated in nasal fluid from carriers for 2 h at 37 degrees C were less damaged than those incubated in noncarrier fluid and were coated with an electron-dense layer. Compared with that from healthy donors and patients with acute rhinitis, nasal fluid from carriers contained elevated concentrations of the neutrophil-derived defensins human neutrophil peptides 1 to 3 (47- and 4-fold increases, respectively), indicative of a neutrophil-mediated inflammatory host response to S. aureus colonization. The concentration of the inducible epithelial antimicrobial peptide human beta-defensin 2 was also highly elevated compared to that in healthy donors, in whom the level was below the detection limit, or patients with acute rhinitis (sixfold increase). Thus, nasal carriage of S. aureus takes hold in nasal fluid that is permissive for colonization and induces a local inflammatory response that fails to clear the colonizing bacteria.     

Is E/E′ reliable in patients with regional wall motion abnormalities to estimate left ventricular filling pressure?

Background There is limited data on the diagnostic utility of the transmitral to mitral annular velocity (E/E′) by tissue Doppler imaging (TDI) in the presence of regional wall motion abnormalities (RWMA). We aimed to investigate whether the E/E′ is reliable in estimating left ventricular filling pressure (LVFP) despite RWMA. Methods One hundred thirty consecutive patients with myocardial infarction (MI) and subsequent RWMA referred for cardiac catheterization and echocardiography to measure LV pre-A pressure (LVP_PRE-A) and Doppler signals from the mitral inflow with tissue Doppler imaging (TDI) of the mitral annulus. All patients were classified into three groups according to RWMA of the segment adjacent to the E′-measuring point using TDI: 83 patients with normal wall motions of the basal septal and basal lateral segments (group A); 28 patients with RWMA of the basal septum (group B); and 19 patients with RWMA of the basal lateral segment (group C). Results Septal E/E′ correlated with LVP_PRE-A in groups A and C (r = 0.383, P < 0.001; r = 0.482, P = 0.037, respectively). Lateral E/E′ and LVP_PRE-A showed good correlation in groups A, B and C (r = 0.470, P < 0.001; r = 0.416, P = 0.028; r = 0.727, P < 0.001, respectively). The largest area under the receiver operating curve was obtained by the lateral E/E′ for the prediction of a high LVFP, irrespective of the location of RWMA. Conclusions In selected patients with abnormal wall motion of the basal septum, E/E′ measured at the septum was not representative for LVFP. Lateral E/E′ is reliable for the prediction of high LVFP, regardless of the site of RWMA.     

The pattern of Tpeak–Tend and QT interval,and J wave during therapeutic hypothermia

Background and Purpose

The electrocardiogram manifestations of hypothermia include J waves and prolongation of QT intervals. This study described changes in repolarization patterns during therapeutic hypothermia (TH).

Methods

We measured the QTc and the interval from the peak to the end of the T wave (TpTe) from the V₄ and V₆ leads in 20 patients with TH. The TpTe was also expressed as a ratio to the duration of QT ([TpTe/QT] × 100%), and to the corrected value for heart rate (TpTe/√RR).

Results

The QTc became prolonged in all patients during TH. While the TpTe/√RR did not change, the ([TpTe/QTe] × 100%] decreased significantly during TH. The J wave developed during TH in seven patients. With one patient, ventricular fibrillation occurred preceded by an abnormal J wave and prolonged TpTe during TH.

Conclusions

QTc prolongation without TpTe increase or abnormal J wave may not be arrhythmogenic during TH.