Next-Generation-Sequencing-Based Hospital Outbreak Investigation Yields Insight into Klebsiella aerogenes Population Structure and Determinants of Carbapenem Resistance and Pathogenicity.

Klebsiella aerogenes is a nosocomial pathogen associated with drug resistance and outbreaks in intensive care units. In a 5-month period in 2017, we experienced an increased incidence of cultures for carbapenem-resistant K. aerogenes (CR-KA) from an adult cardiothoracic intensive care unit (CICU) involving 15 patients. Phylogenomic analysis following whole-genome sequencing (WGS) identified the outbreak CR-KA isolates to group together as a tight monoclonal cluster (with no more than six single nucleotide polymorphisms [SNPs]), suggestive of a protracted intraward transmission event. No clonal relationships were identified between the CICU CR-KA strains and additional hospital CR-KA patient isolates from different wards and/or previous years. Carbapenemase-encoding genes and drug-resistant plasmids were absent in the outbreak strains, and carbapenem resistance was attributed to mutations impacting AmpD activity and membrane permeability. The CICU outbreak strains harbored an integrative conjugative element (ICE) which has been associated with pathogenic Klebsiella pneumoniae lineages (ICEKp10). Comparative genomics with global K. aerogenes genomes showed our outbreak strains to group closely with global sequence type 4 (ST4) strains, which, along with ST93, likely represent dominant K. aerogenes lineages associated with human infections. For poorly characterized pathogens, scaling analyses to include sequenced genomes from public databases offer the opportunity to identify emerging trends and dominant clones associated with specific attributes, syndromes, and geographical locations.

Cumulative antibiotic exposures over time and the risk of Clostridium difficile infection.

BACKGROUND: Clostridium difficile infection (CDI) is a major cause of hospital-acquired diarrhea and is most commonly associated with changes in normal intestinal flora caused by administration of antibiotics. Few studies have examined the risk of CDI associated with total dose, duration, or number of antibiotics while taking into account the complex changes in exposures over time. METHODS: A retrospective cohort study conducted from 1 January to 31 December 2005 among hospitalized patients 18 years or older receiving 2 or more days of antibiotics. RESULTS: The study identified 10,154 hospitalizations for 7,792 unique patients and 241 cases of CDI, defined as the detection of C. difficile toxin in a diarrheal stool sample within 60 days of discharge. We observed dose-dependent increases in the risk of CDI associated with increasing cumulative dose, number of antibiotics, and days of antibiotic exposure. Compared to patients who received only 1 antibiotic, the adjusted hazard ratios (HRs) for those who received 2, 3 or 4, or 5 or more antibiotics were 2.5 (95% confidence interval [CI] 1.6-4.0), 3.3 (CI 2.2-5.2), and 9.6 (CI 6.1-15.1), respectively. The receipt of fluoroquinolones was associated with an increased risk of CDI, while metronidazole was associated with reduced risk. CONCLUSIONS: Cumulative antibiotic exposures appear to be associated with the risk of CDI. Antimicrobial stewardship programs that focus on the overall reduction of total dose as well as number and days of antibiotic exposure and the substitution of high-risk antibiotic classes for lower-risk alternatives may reduce the incidence of hospital-acquired CDI.

Non-ventilator health care-associated pneumonia (NV-HAP): Pathogenesis and microbiology of NV-HAP.

Studies demonstrate that those at risk for developing nonventilator associated pneumonia (NV-HAP) include the very young and the very old, as well as persons with compromised immune systems cardiovascular and/or pulmonary disease. This section includes a review of the pathogenesis and microbiology of NV-HAP, including bacterial as well as viral and fungal pathogens. Etiology, modes of transmission, and specific prevention strategies associated with various causative microorganisms are highlighted.

Student self-screening for methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization in hand hygiene education.

OBJECTIVE: To determine the feasibility and effectiveness of adding a hand hygiene exercise in self-screening for Methicillin-Resistant Staphylococcus Aureus (MRSA) nasal colonization to a health care delivery course for first-year pharmacy (P1) students. DESIGN: About one month after students were trained in hand hygiene technique and indications, faculty members demonstrated how to self-screen for MRSA nasal colonization. Students were then asked to screen themselves during the required class time. Aggregated class results were shared and compared to prevalence estimates for the general population and health care providers. ASSESSMENT: The 71 students present in class on the day of the self-screening exercise chose to participate. A survey comparing presecreening and postscreening responses indicated incremental improvements in student knowledge and awareness of health care associated infections and motivation to perform hand hygiene. On the written exam, student performance demonstrated improved knowledge compared to previous class years. CONCLUSION: Self-screening for MRSA nasal colonization in a health care delivery course for P1 students increased students' motivation to perform hand hygiene techniques and follow indications promulgated by the World Health Organization.

Decreased sepsis related to indwelling venous access devices coincident with implementation of universal leukoreduction of blood transfusions.

BACKGROUND: Randomized trials and animal models demonstrate that leukoreduction of transfusions can reduce the risk of post-operative infections. We performed a retrospective study of sepsis related to indwelling venous access devices (line related infections) before and after the July 2000 implementation of universal leukoreduction. METHODS: Line related infection data were collected from hospital infection control records for an 18-month period before and after July 2000. Transfusion histories were obtained from transfusion service records. RESULTS: Line related infections decreased in number from 150 to 98 (-35%) in transfused patients after implementation of universal leukoreduction, whereas line related infections increased from 41 to 45 (+10%) in nontransfused patients (p = 0.04). This corresponded to a decrease from 5.3 to 3.3 infections/10,000 patient days in transfused patients (p = 0.002). The infection rate remained stable in nontransfused patients at 1.5 infections/10,000 patient days both pre- and postimplementation of universal leukoreduction. Quantitatively similar decreases (33-45%) were seen in transfused surgical, medical and pediatric patients. CONCLUSIONS: A substantial and statistically significant decrease in line related infections occurred coincident with implementation of universal leukoreduction. These improved outcomes were observed in transfused but not nontransfused patients, across all clinical services, suggesting a causal relationship with universal leukoreduction.