Surveillance of methicillin-resistant Staphylococcus aureus in a pediatric hospital in Mexico City during a 7-year period (1997 to 2003): clonal evolution and impact of infection control.

Between 1997 and 2000 a single multidrug-susceptible methicillin-resistant Staphylococcus aureus clone, M (sequence type 30 [ST30]-staphylococcal cassette chromosome mec [SCCmec] type IV), was present in a pediatric hospital in Mexico City, Mexico. In 2001 the international multidrug-resistant New York-Japan clone (ST5-SCCmec type II) was introduced into the hospital, completely replacing clone M by 2002.

Prevalence of serological markers against measles, rubella, varicella, hepatitis B, hepatitis C, and human immunodeficiency virus among medical residents in Mexico.

BACKGROUND: Vaccination programs among health care workers are based on seroprevalence studies, which seldom include medical residents or students. The objective of this study was to determine the seroprevalence of antibodies against measles, rubella, varicella, hepatitis B (HBV), hepatitis C (HCV), and human immunodeficiency virus (HIV) among medical residents. METHODS: This study was designed as a prospective survey. A self-reported questionnaire was used to obtain the information. Serum samples were tested for antibodies by commercial immunoenzymatic assays. Statistical analysis was descriptive; history of exposure was evaluated as a diagnostic test and sensitivity, specificity, and predictive values were calculated according to Bayes theorem. RESULTS: Eighty-nine residents were included, the median age was 27 years, and 58 (65.2%) were female. Seventy-two (79.7%) had been vaccinated against HBV, but vaccination was complete in only 30/72 (41.6%). All were positive for measles and varicella, with the exception of one case for each. The serology for rubella was negative in 12 residents (10 women). Three residents had anti-core against HBV, with negative surface antigen. One positive case for HCV was confirmed by Western blot. All were negative for HIV. A history of prior varicella had a 100% positive predictive value; in contrast, the negative predictive value was quite low (7%). CONCLUSIONS: Negative serology for rubella among women and incomplete vaccination against HBV support the implementation of vaccination programs in medical schools in Mexico.

Blood culture and respiratory syncytial virus identification in acute lower respiratory tract infection.

Even though the incidence of pneumonia in developed and developing countries is similar, the mortality is five times higher in developing countries. This study aimed to determine the prevalence of bacteremia in children with acute lower respiratory tract infection (LRTI) and relative contribution of respiratory syncytial virus (RSV). One hundred and one children under five years of age who attended a primary care level clinic with diagnosis of acute LRTI, were enrolled. Diagnosis and management of pneumonia were done according to the WHO guidelines. Two blood cultures were drawn at the time of admission. A nasopharyngeal sample was taken for detection of RSV by indirect immunofluorescence. Blood cultures were positive for pathogenic bacteria (Streptococcus pneumoniae, Haemophilus influenzae and Staphylococcus aureus) in three patients. The detection for RSV was positive in 24 patients (23.7%). The clinical and radiographic presentations were not significantly different between patients with and without RSV (p > 0.05). RSV is a common cause of LRTI in children younger than five years old. Blood cultures are not commonly positive in outpatients with acute LRTI. The practice of obtaining blood cultures in primary and secondary care clinics is not useful to guide the treatment of patients with community-acquired pneumonia.