title: Seasonal variations and influence of the weather on the appearance of peritoneal infection.
abstract: BACKGROUND
  Peritoneal infections are a common complication in patients undergoing peritoneal dialysis (PD) and are frequently the cause of the failure of the technique. Knowing the factors that can lead to their appearance helps to establish preventative measures.
  
  
  OBJECTIVE
  To understand the influence of climatic variables in the appearance of peritonitis, such as seasonal variation, the temperature and humidity in Asturias.
  
  
  METHODS
  A retrospective, observational study of all peritoneal infections that occurred in our PD department over a period of 5 years (2007-2011). The region was divided lengthways into three areas: the coast, central area and mountains, each of which has a climatological season for reference, which is defined by the State Meteorology Agency (AEMET) (in Gij&oacute;n, Oviedo and Mieres, respectively). The AEMET provided us with data on the humidity and average temperature of the months in which all the cases of peritonitis appeared.
  
  
  RESULTS
  There were 171 cases of peritonitis (0.498 episodes/patient/year) in 201 patients (58&plusmn;16 years, 59% males, 33% diabetics, 20&plusmn;19 months on technique). We did not find any differences according to age, sex, having diabetes, nasal carrier status for Staphylococcus aureus or therapeutic modality. Overall, there were no differences among seasons. However, using spring as a reference (value 1), the incidence rate of gram-negative peritonitis (95% confidence interval) in summer, autumn and winter was 0.666 (0.211-1.832), 0.248 (0.000-0.912) and 0.292 (0.000-0.833), respectively (P&lt;.001). We do not see this variation upon analysing the incidence rates of peritonitis caused by gram-positive bacteria. The average temperature of the days on which peritoneal infections were caused by gram-negative bacteria (15.46&plusmn;3.71&deg;C) was significantly higher than on those days when it was caused by gram-positive bacteria (13.61&plusmn;3.89 &deg;C) (P.022). There are no significant differences in relation to humidity (78.76 &plusmn; 4.40 vs. 77.5&plusmn;3.69 %) (P.227).
  
  
  CONCLUSIONS
  Overall, the rates of peritoneal infection are similar in all four seasons of the year, although in the case of gram-negative bacteria there is an increase in its incidence in spring and summer. The higher the temperature, the higher the risk that a peritoneal infection will be the result of a gram-negative bacterium.
authors.forename: Miguel
authors.initials: M
authors.lastname: Núñez-Moral
authors.forename: J Emilio
authors.initials: JE
authors.lastname: Sánchez-Álvarez
authors.forename: Isabel
authors.initials: I
authors.lastname: González-Díaz
authors.forename: Beatriz
authors.initials: B
authors.lastname: Peláez-Requejo
authors.forename: Aurora
authors.initials: A
authors.lastname: Quintana-Fernández
authors.forename: Carmen
authors.initials: C
authors.lastname: Rodríguez-Suárez
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002353:Carrier State / Q000453:epidemiology; D060085:Coinfection / Q000453:epidemiology; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000209:etiology; D003428:Cross Infection / Q000453:epidemiology / Q000209:etiology; D003928:Diabetic Nephropathies / Q000453:epidemiology / Q000628:therapy; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000453:epidemiology* / Q000209:etiology; D016908:Gram-Positive Bacterial Infections / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D007676:Kidney Failure, Chronic / Q000453:epidemiology / Q000628:therapy; D008297:Male; D008685:Meteorological Concepts; D008875:Middle Aged; D010530:Peritoneal Dialysis / Q000009:adverse effects*; D010538:Peritonitis / Q000453:epidemiology* / Q000209:etiology; D012189:Retrospective Studies; D012621:Seasons; D013030:Spain / Q000453:epidemiology; D013203:Staphylococcal Infections / Q000453:epidemiology; D013696:Temperature