Perioperative antimicrobial prophylaxis and prevention of hepatobiliary surgical site infections.

OBJECTIVE: To characterize the microbiology of hepatobiliary surgical site infections (SSIs) and to explore the relationship between specific antimicrobial prophylaxis regimens and the development of SSIs. DESIGN: Retrospective matched case-control study comparing patient, procedure, and antimicrobial prophylaxis characteristics among patients undergoing a hepatobiliary surgical procedure with and without an SSI. SETTING: A tertiary referral acute-care facility. METHODS: Patients undergoing procedures defined as "BILI" (bile duct, liver, or pancreas surgery) using National Healthcare Safety Network (NHSN) definitions, excluding those undergoing concomitant liver transplantation, from January 2013 through June 2016 were included in the study population. The SSIs were identified through routine infection control surveillance using NHSN definitions. All patients who developed an SSI were considered cases. Controls were selected randomly matched 2:1 with cases based on fiscal quarter of the procedure. Logistic regression modeling was performed to explore variables associated with SSI, including antimicrobial prophylaxis received. RESULTS: Among 975 procedures, 80 (8.2%) resulted in an SSI. Most cases involved an organism nonsusceptible to standard prophylaxis regimens, including cefazolin (68.8%), cefazolin plus metronidazole (61.3%), and ampicillin-sulbactam (52.5%). In a multivariate model, antimicrobial coverage against Enterococcus spp (aOR, 0.58; 95% confidence interval [CI], 0.17-2.04; P=.40) and against Pseudomonas spp (aOR, 2.40; 95% CI, 0.56-10.29; P=.24) were not protective against the development of an SSI. The presence of a documented ß-lactam allergy was significantly associated with the development of an SSI (aOR, 3.54; 95% CI, 1.36-9.19; P=.009). CONCLUSIONS: Although SSIs at the study institution were associated with pathogens nonsusceptible to the most commonly used prophylaxis regimens, broader-spectrum coverage was not associated with a reduction in SSIs.

Correlation of Hand Hygiene Compliance Measured by Direct Observation with Estimates Obtained from Product Usage.

Improving compliance with hand hygiene is a cornerstone of infection prevention. However, data regarding practical methods for monitoring compliance are limited. We found that product use metrics have a moderate correlation with direct observation in ward settings and limited correlation in intensive care units.Infect Control Hosp Epidemiol 2018;39:746-749.

Investigation of a Candida guilliermondii Pseudo-outbreak Reveals a Novel Source of Laboratory Contamination.

Candida guilliermondii was isolated from sterile specimens with increasing frequency over a several-month period despite a paucity of clinical evidence suggesting true Candida infections. However, a health care-associated outbreak was strongly considered due to growth patterns in the microbiology laboratory that were more consistent with true infection than environmental contamination. Therefore, an extensive investigation was performed to identify its cause. With the exception of one case, patient clinical courses were not consistent with true invasive fungal infections. Furthermore, no epidemiologic link between patients was identified. Rather, extensive environmental sampling revealed C. guilliermondii in an anaerobic holding jar in the clinical microbiology laboratory, where anaerobic plates were prereduced and held before inoculating specimens. C. guilliermondii grows poorly under anaerobic conditions. Thus, we postulate that anaerobic plates became intermittently contaminated. Passaging from intermittently contaminated anaerobic plates to primary quadrants of aerobic media during specimen planting yielded a colonial growth pattern typical for true specimen infection, thus obscuring laboratory contamination. A molecular evaluation of the C. guilliermondii isolates confirmed a common source for pseudo-outbreak cases but not for the one true infection. In line with Reason's model of organizational accidents, active and latent errors coincided to contribute to the pseudo-outbreak. These included organism factors (lack of growth in anaerobic conditions obscuring plate contamination), human factors (lack of strict adherence to plating order, leading to only intermittent observation of aerobic plate positivity), and laboratory factors (novel equipment). All of these variables should be considered when evaluating possible laboratory-based pseudo-outbreaks.

Health and economic burden of post-partum Staphylococcus aureus breast abscess.

OBJECTIVES: To determine the health and economic burdens of post-partum Staphylococcus aureus breast abscess. STUDY DESIGN: We conducted a matched cohort study (N = 216) in a population of pregnant women (N = 32,770) who delivered at our center during the study period from 10/1/03-9/30/10. Data were extracted from hospital databases, or via chart review if unavailable electronically. We compared cases of S. aureus breast abscess to controls matched by delivery date to compare health services utilization and mean attributable medical costs in 2012 United States dollars using Medicare and hospital-based estimates. We also evaluated whether resource utilization and health care costs differed between cases with methicillin-resistant and -susceptible S. aureus isolates. RESULTS: Fifty-four cases of culture-confirmed post-partum S. aureus breast abscess were identified. Breastfeeding cessation (41%), milk fistula (11.1%) and hospital readmission (50%) occurred frequently among case patients. Breast abscess case patients had high rates of health services utilization compared to controls, including high rates of imaging and drainage procedures. The mean attributable cost of post-partum S. aureus breast abscess ranged from $2,340-$4,012, depending on the methods and data sources used. Mean attributable costs were not significantly higher among methicillin-resistant vs. -susceptible S. aureus cases. CONCLUSIONS: Post-partum S. aureus breast abscess is associated with worse health and economic outcomes for women and their infants, including high rates of breastfeeding cessation. Future study is needed to determine the optimal treatment and prevention of these infections.

Risk factors for Staphylococcus aureus postpartum breast abscess.

BACKGROUND: Staphylococcus aureus (SA) breast abscesses are a complication of the postpartum period. Risk factors for postpartum SA breast abscesses are poorly defined, and literature is conflicting. Whether risk factors for methicillin-resistant SA (MRSA) and methicillin-susceptible SA (MSSA) infections differ is unknown. We describe novel risk factors associated with postpartum breast abscesses and the changing epidemiology of this infection. METHODS: We conducted a cohort study with a nested case-control study (n = 216) involving all patients with culture-confirmed SA breast abscess among >30 000 deliveries at our academic tertiary care center from 2003 through 2010. Data were collected from hospital databases and through abstraction from medical records. All SA cases were compared with both nested controls and full cohort controls. A subanalysis was completed to determine whether risk factors for MSSA and MRSA breast abscess differ. Univariate analysis was completed using Student's t test, Wilcoxon rank-sum test, and analysis of variance, as appropriate. A multivariable stepwise logistic regression was used to determine final adjusted results for both the case-control and the cohort analyses. RESULTS: Fifty-four cases of culture-confirmed abscess were identified: 30 MRSA and 24 MSSA. Risk factors for postpartum SA breast abscess in multivariable analysis include in-hospital identification of a mother having difficulty breastfeeding (odds ratio, 5.00) and being a mother employed outside the home (odds ratio, 2.74). Risk factors did not differ between patients who developed MRSA and MSSA infections. CONCLUSIONS: MRSA is an increasingly important pathogen in postpartum women; risk factors for postpartum SA breast abscess have not changed with the advent of community-associated MRSA.

Spread of methicillin-resistant Staphylococcus aureus in a large tertiary NICU: network analysis.

OBJECTIVE: Methicillin-resistant Staphylococcus aureus (MRSA) colonization in NICUs increases the risk of nosocomial infection. Network analysis provides tools to examine the interactions among patients and staff members that put patients at risk of colonization. METHODS: Data from MRSA surveillance cultures were combined with patient room locations, nursing assignments, and sibship information to create patient- and unit-based networks. Multivariate models were constructed to quantify the risk of incident MRSA colonization as a function of exposure to MRSA-colonized infants in these networks. RESULTS: A MRSA-negative infant in the NICU simultaneously with a MRSA-positive infant had higher odds of becoming colonized when the colonized infant was a sibling, compared with an unrelated patient (odds ratio: 8.8 [95% confidence interval [CI]: 5.3-14.8]). Although knowing that a patient was MRSA-positive and was placed on contact precautions reduced the overall odds of another patient becoming colonized by 35% (95% CI: 20%-47%), having a nurse in common with that patient still increased the odds of colonization by 43% (95% CI: 14%-80%). Normalized group degree centrality, a unitwide network measure of connectedness between colonized and uncolonized patients, was a significant predictor of incident MRSA cases (odds ratio: 18.1 [95% CI: 3.6-90.0]). CONCLUSIONS: Despite current infection-control strategies, patients remain at significant risk of MRSA colonization from MRSA-positive siblings and from other patients with whom they share nursing care. Strategies that minimize the frequency of staff members caring for both colonized and uncolonized infants may be beneficial in reducing the spread of MRSA colonization.