Methicillin resistant Staphylococcus aureus among nurses in a tertiary care hospital in northern Sri Lanka

During the 2011 dengue outbreak, health care providers in Colombo, Sri Lanka noticed a slow rise in platelet counts in patients recovering from dengue fever when compared to the 2010 outbreak. This study was carried out to confirm this observation. The platelet recovery rates of two groups of patients from 2010 and 2011 (n=28 and n=25 respectively) were computed and compared. The platelet recovery rates, of patients from the 2011 outbreak were found to be slower than the platelet recovery rates of patients from the 2010 outbreak (p value=0.0089). Ceylon Medical Journal 2014; 59: 61-63 Introduction Dengue fever (DF) and dengue haemorrhagic fever (DHF) is endemic in Sri Lanka. Following the first reported dengue outbreak in 1965, the frequency and magnitude of dengue outbreaks are on the rise. Particularly large outbreaks were reported in the years 2002, 2004 and 2009 [1, 2]. Thrombocytopenia in DF recovers with clinical improvement. The increment of the platelet count is used as a feature of recovery as well as a discharge criterion in clinical practice [3]. During the 2011 outbreak, health care providers in Colombo, Sri Lanka observed a slow rise in platelet counts among patients recovering from DF/DHF when compared to the 2010 outbreak. This study was carried out to confirm or refute this observation. Methods The Central Hospital is a tertiary care private hospital located in the commercial capital Colombo. Records were retrieved of all patients confirmed with dengue fever who were admitted to the hospital, during the months of June, July and August in 2010 and 2011. Patients between the ages of 12-65 years, without any concurrent conditions were included in the study. They were confirmed to have DF/DHF through clinical assessment by the treating physician and laboratory confirmation by NS1 antigen positivity or positive IgM serology. The protocol for the Departments of 1Pathology and 2Clinical Medicine, Faculty of Medicine, University of Colombo and Department of 3Mathematics, Faculty of Science, University of Colombo, Sri Lanka. Correspondence: LG, e-mail: <viranjan.gooneratne@yahoo.co.uk>. Received 26 September 2012 and revised version accepted 25 November 2013. Competing interests: none declared. study was approved by the Ethics Review Committee of the Faculty of Medicine, University of Colombo. Serial platelet counts performed during the recovery period were extracted from each patient and scatter plots of platelet counts were drawn against time. The above model was converted to a linear curve using the natural logarithm of platelet count of each patient. The Gradient (α) and Intercept (ln (β)) of each regression line was recorded and average platelet recovery rate of each patient was calculated using α and β as follows. Where T is the time length in which platelet counts of relevant patients were recorded. The average platelet recovery rates of patients in 2010 were compared with patients in 2011 using the Mann Whitney test. The platelet recovery rates and lowest and highest platelet counts obtained from each patient are shown in Table 1. Results Forty four patients from the year 2010 (Group 1) and 42 patients from the year 2011 (Group 2) fulfilled the inclusion criteria for the study. Depending on the fit of the regression model, we were able to obtain recovery rates for 28 patients in group 1 and 25 patients in group 2. Therefore 16 patients from group 1 and 17 patients from group 2 had to be excluded from the data analysis as they did not have sufficient data points (less than four data points) to find a reasonable platelet recovery rate. The age (p=0.67) and sex (p=0.34) distribution between the groups did not differ significantly. The results of the Mann Whitney test is given below, n1 -Sample size of smaller group – Platelet recovery rate of 2011 = 25 n2 Sample size of larger group – Platelet recovery rate of 2010 = 28 R1 Sum of the ranks of group with n1 cases = 533 R2 Sum of the ranks of group with n2 cases =898 Platelet recovery rate at time t = dy = αβe α t dt Average platelet recovery rate = α t dt = β [eα t -1] ∫ Τ