Alison Galdys

Prevalence and Duration of Asymptomatic Clostridium difficile Carriage among Healthy Subjects in Pittsburgh, Pennsylvania

ABSTRACT Previous studies suggested that 7 to 15% of healthy adults are colonized with toxigenic Clostridium difficile. To investigate the epidemiology, genetic diversity, and duration of C. difficile colonization in asymptomatic persons, we recruited healthy adults from the general population in Allegheny County, Pennsylvania. Participants provided epidemiological and dietary intake data and submitted stool specimens. The presence of C. difficile in stool specimens was determined by anaerobic culture. Stool specimens yielding C. difficile underwent nucleic acid testing of the tcdA gene segment with a commercial assay; tcdC genotyping was performed on C. difficile isolates. Subjects positive for C. difficile by toxigenic anaerobic culture were asked to submit additional specimens. One hundred six (81%) of 130 subjects submitted specimens, and 7 (6.6%) of those subjects were colonized with C. difficile. Seven distinct tcdC genotypes were observed among the 7 C. difficile-colonized individuals, including tcdC genotype 20, which has been found in uncooked ground pork in this region. Two (33%) out of 6 C. difficile-colonized subjects who submitted additional specimens tested positive for identical C. difficile strains on successive occasions, 1 month apart. The prevalence of C. difficile carriage in this healthy cohort is concordant with prior estimates. C. difficile-colonized individuals may be important reservoirs for C. difficile and may falsely test positive for infections due to C. difficile when evaluated for community-acquired diarrhea caused by other enteric pathogens.

Asymptomatic Clostridium difficile colonization as a reservoir for Clostridium difficile infection

Clostridium difficile (CD) infection (CDI) is the leading cause of healthcare associated diarrhea despite intense hospital infection prevention programs. A substantial proportion of the population is asymptomatically colonized with CD, and evidence is mounting that these individuals serve as a reservoir for CDI. The purpose of this review is to discuss the mechanisms by which individuals may harbor toxigenic CD but remain asymptomatic, the evidence that asymptomatically colonized individuals serve as a source of CDI, and the implications of this potential CD reservoir for healthcare infection prevention.

Risk Factors for Surgical Site Infections Following Neurosurgical Spinal Fusion Operations: A Case Control Study

OBJECTIVE To determine risk factors for the development of surgical site infections (SSIs) in neurosurgery patients undergoing spinal fusion. DESIGN Retrospective case-control study. SETTING Large, academic, quaternary care center. PATIENTS The study population included all neurosurgery patients who underwent spinal fusion between August 1, 2009, and August 31, 2013. Cases were defined as patients in the study cohort who developed an SSI. Controls were patients in the study cohort who did not develop an SSI. METHODS To achieve 80% power with an ability to detect an odds ratio (OR) of 2, we performed an unmatched case-control study with equal numbers of cases and controls. RESULTS During the study period, 5,473 spinal fusion procedures were performed by neurosurgeons in our hospital. With 161 SSIs recorded during the study period, the incidence of SSIs associated with these procedures was 2.94%. While anterior surgical approach was found to be a protective factor (OR, 0.20; 95% confidence interval [CI], 0.08-0.52), duration of procedure (OR, 1.58; 95% CI, 1.29-1.93), American Society of Anesthesiologists score of 3 or 4 (OR, 1.79; 95% CI, 1.00-3.18), and hospitalization within the prior 30 days (OR, 5.8; 95% CI, 1.37-24.57) were found in multivariate analysis to be independent predictors of SSI following spinal fusion. Prior methicillin-resistant Staphylococcus aureus (MRSA) nares colonization was highly associated with odds 20 times higher of SSI following spinal fusion (OR, 20.30; 95% CI, 4.64-8.78). CONCLUSIONS In additional to nonmodifiable risk factors, prior colonization with MRSA is a modifiable risk factor very strongly associated with development of SSI following spinal fusion. Infect Control Hosp Epidemiol 2017;38:348-352.

1646Evidence of hospital-associated Clostridium difficile transmission between patients with asymptomatic carriage and patients with Clostridium difficile infection

Background. Despite strategies to reduce transmission, Clostridium difficile (CD) remains a leading cause of morbidity in health care settings. The aims of our study were (1) to determine if asymptomatic inpatient CD carriers can be liked by molecular epidemiology to other inpatients with CD infection (CDI) and (2) to determine if active surveillance testing (AST) criteria to identify inpatients at risk for vancomycin-resistant Enterococcus (VRE) colonization are sufficiently sensitive to capture asymptomatic CD carriage. Methods. Over a 5 day period, all inpatients at University of Pittsburgh Medical Center – Presbyterian Hospital (UPMC) were targeted for one-time AST for CD via perirectal sampling. Archived stool specimens were obtained from (1) clinical CDI cases 7 weeks prior to AST for CD, (2) clinical CDI cases during AST for CD, and (3) clinical hospital-associated CDI (HA-CDI) cases 12 weeks after AST for CD. CD carriage was defined as AST positivity in the absence of clinical CDI during or +/3 months from AST; clinical CDI was defined as clinician-requested, nucleic stool test positivity for toxigenic CD. Specimens were cultured for CD using broth enrichment. CD isolates were typed using tcdC and multilocus variable number tandem repeat (MLVA) genotyping. Isolates whose MLVA genotypes had a summed tandem-repeat difference of ≤2 were considered highly related. “Probable” transmission events were inferred when patients exhibited simultaneous occupancy of the same inpatient ward and their isolates were highly related. “Possible” transmission events were inferred when patients exhibited simultaneous occupancy of the hospital, but not the same inpatient ward, and their isolates were highly related. AST for VRE was performed according to UPMC policy throughout. Results. 53 (10%) inpatients were identified as CD carriers. 123 clinical CDI cases were identified; isolates from 101 (83%) of these episodes were obtained. 6 (5.9%) clinical CDI isolates were highly related to CD carrier isolates, 4 of which were HA and could be linked epidemiologically to CD carriers – 2 by probable and 2 by possible transmission events. None of the CD carriers implicated in transmission events underwent VRE AST. Conclusion. Hospital-wide AST for CD carriage may identify a reservoir of CD involved in CDI. Disclosures. All authors: No reported disclosures.