Molecular epidemiology of CTX-M producing Enterobacteriaceae isolated from bloodstream infections in Rio de Janeiro, Brazil: emergence of CTX-M-15

OBJECTIVE: The present studywas designed to evaluate the molecular epidemiology of CTX-M producing Klebsiella pneumoniae, Enterobacter cloacae and Escherichia coli isolated from bloodstream infections at tertiary care hospitals in the State of Rio de Janeiro, Brazil. MATERIAL AND METHODS: A total of 231 nonduplicate Enterobacteriaceae were isolated from five Brazilian hospitals between September 2007 and September 2008. The antimicrobial susceptibility testing was performed by disk diffusion method according to the Clinical Laboratory Standard Institute. Isolates showing resistance to third-generation cephalosporins were screened for ESBL activity by the double-disk synergy test. The presence of blaCTX-M , blaCTX-M-15 and blaKPC genes was determined by Polymerase Chain Reaction (PCR) amplification andDNA sequencing. The molecular typing of CTX-M producing isolateswas performed by pulsed-field gel electrophoresis (PFGE). RESULTS AND DISCUSSION: Ninety-three isolates were screened as ESBL positive and 85 (91%) were found to carry CTX-M-type, as follows: K. pneumoniae 59 (49%), E. cloacae 15 (42%), and E. coli 11 (15%). Ten isolates resistant for carbapenems in K. pneumoniae were blaKPC-2 gene positive. Among CTX-M type isolates, CTX-M-15 was predominant in more than 50% of isolates for K. pneumoniae, E. coli, and E. cloacae. PFGE analysis of CTX-M producing isolates showed the predominance of CTX-M-15 in 10 of 24 pulsotypes in K. pneumoniae, 6 of 13 in E. cloacae and 3 of 6 in E. coli. CTX-M-15 was also predominant among KPC producing isolates. In conclusion, this study showed that CTX-M-15 was circulating in Rio de Janeiro state in 2007-2008. This data reinforce the need for continuing surveillance because this scenario may have changed over the years.

Factors associated with epidemic multiresistant Pseudomonas aeruginosa infections in a hospital with AIDS-predominant admissions

INTRODUCTION: Infections caused by multiresistant Pseudomonas aeruginosa (MR-PA) have been associated with persistent infections and high mortality in acquired immunodeficiency syndrome (AIDS) patients. Therefore, understanding the predisposing factors for infection/colonization by this agent is critical for controlling outbreaks caused by MR-PA in settings with AIDS patients. OBJECTIVEAND METHODS: To analyze the presence of factors associated with the acquisition of an epidemic MR-PA strain in a hospital with AIDS-predominant admission. A case-control study was carried out in which cases and controls were gathered from a prospective cohort of all hospitalized patients in an infectious disease hospital during a five-year study period. RESULTS: Multivariate logistic regression analysis demonstrated that enteral nutrition OR = 14.9), parenteral nutrition (OR = 10.7), and use of ciprofloxacin (OR = 8.9) were associated with a significant and independent risk for MR-PA acquisition. CONCLUSIONS: Although cross-colonization was likely responsible for the outbreaks, the use of ciprofloxacin was also an important factor associated with the acquisition of an epidemic MR-PA strain. More studies are necessary to determine whether different types of nutrition could lead to modification of gastrointestinal flora, thereby increasing the risk for infection/colonization by MR-PA in this population.

Outbreaks, persistence, and high mortality rates of multiresistant Pseudomonas aeruginosa infections in a hospital with AIDS-predominant admissions

INTRODUCTION: Authors have reported increased incidence of multiresistant Pseudomonas aeruginosa (MR-PA) infections worldwide over the last decade. Researchers have proposed multifaceted approaches to control MR-PA infections, but none have been reported in the acquired immunodeficiency syndrome (AIDS) setting. OBJECTIVE AND METHODS: Herein we report the impact of a multifaceted intervention for controlling MR-PA over five years in a hospital with AIDS-predominant admissions and describe the clinical characteristics of MR-PA infection in our patient population. The clinical outcomes of infected patients and molecular characteristics of the isolated strains were used as tools for controlling MR-PA infection rates. RESULTS: Significant temporary decrease of new infections was achieved after intervention, although a high level of diagnostic suspicion of nosocomial infection was maintained. We obtained 35 P. aeruginosa isolates with multiresistant profiles from 13 infected and 3 colonized patients and 2 environmental samples. Most of the patients (94 percent) were immunocompromised with AIDS (n = 10) or HTLV-1 infections (n = 5). Of the followed patients, 67 percent had persistent and/or recurrent infections, and 92 percent died. We observed differences in the antibiotic-resistance pattern of MR-PA infection/colonization during two outbreaks, although the genetic profiles of the tested strains were identical. CONCLUSIONS: Therefore, we concluded that early multidisciplinary interventions are essential for reducing the burden caused by this microorganism in patients with AIDS. Prolonged or suppressive antibiotic-based therapy should be considered for MR-PA infections in patients with AIDS because of the persistence characteristic of MR-PA in these patients.