Variability of Staphylococcus Aureus Carriers on a Medicine Student’s Population

Para evaluar en estudiantes de medicina la variación del estado de portador de Staphylococcus aureus y su resistencia antimicrobiana, antes y después de la práctica clínica, se realizó un estudio longitudinal en una cohorte de 159 estudiantes de cuarto y noveno semestre universitario. Se tomaron muestras de las zonas periamigdalianas y/o pared posterior de orofaringe, de las fosas nasales y las manos, se cultivaron en agar sangre de cordero al 5% y se incubaron en aerobiosis a 37°C, durante 48 horas. La identificación de Staphylococcus aureus se realizó según las características macroscópicas y pruebas bioquímicas. La susceptibilidad a los antimicrobianos se evaluó mediante el método de difusión de disco, por la técnica de Kirby-Bauer, siguiendo las normas internacionales del Clinical and Laboratory Standards Institute (CLSI), con los siguientes antimicrobianos: ciprofloxacina, vancomicina, oxacilina, cefalotina,clindamicina y rifampicina. La edad promedio de los alumnos de cuarto semestre fue 19,1±1,2 años y el género femenino fue 2/1 más frecuente que el masculino. Se analizaron la presencia de antecedentes como: infecciones, alergias, estado de fumador, otras patologías no infecciosas, uso de antibióticos en los últimos tres meses y procedimientos quirúrgicos u hospitalizaciones seis meses previos a la toma de las muestras. No hubo relación significativa entre la incidencia del estado de portador y los antecedentes estudiados. Se observó un aumento significativo del 15,1%, con respecto al grupo de estudiantes de cuarto semestre, en el estado de portador de S. aureus en el grupo de estudiantes de noveno semestre, después de haber estado expuestos durante tres años al ambiente hospitalario, (p=0,001 Test exacto de Mc Nemar). De los portadores, el 16,4% presentó la bacteria en manos (p<0,001), el 13,8% en fosas nasales (p=0,0015) y el 3,2% en faringe. Por otra parte,el 35,8% de los portadores presentó persistencia, de los cuales el 25,2% fue en fosas nasales; el 4,4%, en faringe y el 3,8% en manos. En cuanto a la resistencia a los antimicrobianos, el 1,9% de las cepas aisladas de los estudiantes de cuarto semestre presentó resistencia: una a ciprofloxacina y dos a clindamicina (tres estudiantes). Por su parte, el 2,5% de las cepas aisladas de estudiantes de noveno semestre fue resistente: una a cefalotina, ciprofloxacina, oxacilina y clindamicina, una a cefalotina y oxacilina y dos a clindamicina (cuatro estudiantes). En el 1,3% del grupo estudiado se aislaron cepas de Staphylococcus aureus Resistentes a la Meticilina (MRSA, por sus siglas en inglés). Estos resultados no muestran diferencias significativas (p=1.000). This is a longitudinal study performed in a 159 medicine student’s cohort, of fourth and ninth study semester, in order to evaluate the variation of Staphylococcus aureus carriers and its antimicrobial susceptibility on students, before and after clinical practice. Clinical samples were taken with a swab from the tonsils, pharynx posterior wall, nasal fosses and hands and were cultured in 5% sheep blood and incubated at 37oC in aerobic conditions during 48 hours. The identification of Sthaphylococcus aureus was performed according to the phenotypic and biochemical test. The antimicrobial susceptibility was evaluated by the diffusion disc method using the Kirby-Bauer technique, according to Clinical and Laboratory Standards Institute (CLSI), with the following antibiotics: Ciprofloxacyn, Vancomycin, Oxacyclin, Cephalotine, Clyndamycin, and Ryphampycin. The average age of the fourth semester students was 19.1± 1,2 years and the female gender was 2/1 more frequent than the male. The history of infections, allergy, smoke habit, non infectious diseases, surgeries, antibiotic use during the last three months and hospitalizations six months before sampling was analyzed. There was no significant relationship between previous history analysis and the carrier state incidence (p=0.001 Mc Nemar exact Test). A significant increase of 15,1% for S. aureus carrier state was observed after three years of exposure to hospital environment on ninth semester students, compared to fourth semester students (p=0.001 Test Mc Nemar); from which 16.4% (p<0.001) was founded in hands, 13.8% in nasal fosses (p=0.0015) and 3.2% in pharynx. 35.8% of S. aureus carrier was persistent: 25.2% in nasal fosses, 4.4% in pharynx and 3.8% in hands. Antimicrobial resistance was observed in 1.9% of the bacterial strains isolated from fourth semester students: One to Ciprofloxacyn and two to Clyndamycin. Besides was observed 2.5% of bacterial strains isolated from ninth semester students: one to Ciprofloxacyn, Oxacyclin, Cephalotine and Clyndamycin, one to Cephalotine and Oxacyclin and two to Clyndamycin. Finally, Methycylin Resistant Sthaphylococcus Aureus (MRSA) strains were isolated from 1.3% of the studied group. This results didn’t show significant differences b(p=1.000)

Chlamydia trachomatis Frequency in a Cohort of HPV-Infected Colombian Women.

Chlamydia trachomatis (C. trachomatis), an obligate intracellular bacterium, is the commonest infectious bacterial agent of sexual transmission throughout the world. It has been shown that the presence of this bacteria in the cervix represents a risk regarding HPV persistence and, thereafter, in developing cervical cancer (CC). Prevalence rates may vary from 2% to 17% in asymptomatic females, depending on the population being analysed. This study reports the identification of C. trachomatis in a cohort of 219 HPV-infected Colombian females.C. trachomatis infection frequency was determined during each of the study's follow-up visits; it was detected by amplifying the cryptic plasmid sequence by polymerase chain reaction (PCR) using two sets of primers: KL5/KL6 and KL1/KL2. Infection was defined as a positive PCR result using either set of primers at any time during the study. Cox proportional risk models were used for evaluating the association between the appearance of infection and a group of independent variables.Base line C. trachomatis infection frequency was 28% (n = 61). Most females infected by C. trachomatis were infected by multiple types of HPV (77.42%), greater prevalence occurring in females infected with HPV-16 (19.18%), followed by HPV-58 (17.81%). It was observed that females having had the most sexual partners (HR = 6.44: 1.59-26.05 95%CI) or infection with multiple types of HPV (HR = 2.85: 1.22-6.63 95%CI) had the greatest risk of developing C. trachomatis.The study provides data regarding the epidemiology of C. trachomatis /HPV coinfection in different population groups of Colombian females and contributes towards understanding the natural history of C. trachomatis infection

The probability of the risk of the women in this cohort acquiring <i>C</i>. <i>trachomatis</i> infection as time elapsed.

<p>The probability of the risk of the women in this cohort acquiring <i>C</i>. <i>trachomatis</i> infection as time elapsed.</p

The time taken to clear <i>Chlamydia trachomatis</i> infection in the cohort of females initially infected by HPV and <i>C</i>. <i>trachomatis</i>.

<p>The time taken to clear <i>Chlamydia trachomatis</i> infection in the cohort of females initially infected by HPV and <i>C</i>. <i>trachomatis</i>.</p