title: Clinical and epidemiological features and prognosis of complicated pyelonephritis: a prospective observational single hospital-based study.
abstract: BACKGROUND
  Complicated pyelonephritis (cPN), a common cause of hospital admission, is still a poorly-understood entity given the difficulty involved in its correct definition. The aim of this study was to analyze the main epidemiological, clinical, and microbiological characteristics of cPN and its prognosis in a large cohort of patients with cPN.
  
  
  METHODS
  We conducted a prospective, observational study including 1325 consecutive patients older than 14 years diagnosed with cPN and admitted to a tertiary university hospital between 1997-2013. After analyzing the main demographic, clinical and microbiological data, covariates found to be associated with attributable mortality in univariate analysis were included in a multivariate logistic regression model.
  
  
  RESULTS
  Of the 1325 patients, 689 (52%) were men and 636 (48%) women; median age 63 years, interquartile range [IQR] (46.5-73). Nine hundred and forty patients (70.9%) had functional or structural abnormalities in the urinary tract, 215 (16.2%) were immunocompromised, 152 (11.5%) had undergone a previous urinary tract instrumentation, and 196 (14.8%) had a long-term bladder catheter, nephrostomy tube or ureteral catheter. Urine culture was positive in 813 (67.7%) of the 1251 patients in whom it was done, and in the 1032 patients who had a blood culture, 366 (34%) had bacteraemia. Escherichia coli was the causative agent in 615 episodes (67%), Klebsiella spp in 73 (7.9%) and Proteus ssp in 61 (6.6%). Fourteen point one percent of GNB isolates were ESBL producers. In total, 343 patients (25.9%) developed severe sepsis and 165 (12.5%) septic shock. Crude mortality was 6.5% and attributable mortality was 4.1%. Multivariate analysis showed that an age >75 years (OR 2.77; 95% CI, 1.35-5.68), immunosuppression (OR 3.14; 95% CI, 1.47-6.70), and septic shock (OR 58.49; 95% CI, 26.6-128.5) were independently associated with attributable mortality.
  
  
  CONCLUSIONS
  cPN generates a high morbidity and mortality and likely a great consumption of healthcare resources. This study highlights the factors directly associated with mortality, though further studies are needed in the near future aimed at identifying subgroups of low-risk patients susceptible to outpatient management.
authors.affiliation: Infectious Diseases Department, Regional University Hospital, Málaga, Spain. veronicabuonaiuto@yahoo.com.ar.|IBIMA, Malaga University, Malaga, Spain. veronicabuonaiuto@yahoo.com.ar.
authors.forename: Veronica A
authors.initials: VA
authors.lastname: Buonaiuto
authors.affiliation: Infectious Diseases Department, Regional University Hospital, Málaga, Spain. nacho.marquez83@gmail.com.|IBIMA, Malaga University, Malaga, Spain. nacho.marquez83@gmail.com.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Marquez
authors.affiliation: Microbiology Unit, Regional University Hospital, Malaga, Spain. inmadetoro@yahoo.es.|IBIMA, Malaga University, Malaga, Spain. inmadetoro@yahoo.es.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: De Toro
authors.affiliation: Critical Care and Emergency Departments, Regional University Hospital, Malaga, Spain. cjmcarolina@hotmail.com.|IBIMA, Malaga University, Malaga, Spain. cjmcarolina@hotmail.com.
authors.forename: Carolina
authors.initials: C
authors.lastname: Joya
authors.affiliation: Infectious Diseases Department, Regional University Hospital, Málaga, Spain. jdruizmesa@hotmail.com.|IBIMA, Malaga University, Malaga, Spain. jdruizmesa@hotmail.com.
authors.forename: Juan D
authors.initials: JD
authors.lastname: Ruiz-Mesa
authors.affiliation: Critical Care and Emergency Departments, Regional University Hospital, Malaga, Spain. rseara@hotmail.com.|IBIMA, Malaga University, Malaga, Spain. rseara@hotmail.com.
authors.forename: Raimundo
authors.initials: R
authors.lastname: Seara
authors.affiliation: Infectious Diseases Department, Regional University Hospital, Málaga, Spain. antonio-plata@hotmail.com.|IBIMA, Malaga University, Malaga, Spain. antonio-plata@hotmail.com.
authors.forename: Antonio
authors.initials: A
authors.lastname: Plata
authors.affiliation: Infectious Diseases Department, Regional University Hospital, Málaga, Spain. bea_sobrino@yahoo.es.|IBIMA, Malaga University, Malaga, Spain. bea_sobrino@yahoo.es.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Sobrino
authors.affiliation: Microbiology Unit, Regional University Hospital, Malaga, Spain. bpalop@hotmail.com.|IBIMA, Malaga University, Malaga, Spain. bpalop@hotmail.com.
authors.forename: Begoña
authors.initials: B
authors.lastname: Palop
authors.affiliation: Infectious Diseases Department, Regional University Hospital, Málaga, Spain. juan.colmenero.sspa@juntadeandalucia.es.|IBIMA, Malaga University, Malaga, Spain. juan.colmenero.sspa@juntadeandalucia.es.
authors.forename: Juan D
authors.initials: JD
authors.lastname: Colmenero
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016470:Bacteremia / Q000150:complications / Q000382:microbiology; D015331:Cohort Studies; D004926:Escherichia coli / Q000302:isolation & purification; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006785:Hospitals, University; D006801:Humans; D007709:Klebsiella / Q000302:isolation & purification; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D011704:Pyelonephritis / Q000150:complications / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology; D055815:Young Adult