Avish Nagpal

Microbiology and Pathogenesis of Cardiovascular Implantable Electronic Device Infections

Advancements in our understanding of cardiac conduction abnormalities and pathophysiology of congestive heart failure coupled with innovations in device manufacturing and programming have helped to create a demand for a plethora of newer cardiovascular devices over the past 3 decades. Appropriate use of cardiovascular implantable electronic devices (CIEDs) in carefully selected patients is associated with better survival and significant improvements in quality of life.1 Cardiac resynchronization therapy devices are the newest “breed” to join an existing and growing family of permanent pacemakers (PPMs) and implantable cardioverter-defibrillators (ICDs). The number of cardiac devices implanted each year continues to grow exponentially. Unfortunately, because of the invasive nature of the implantation procedures required for placement of these devices and multiple comorbid conditions in device recipients, the benefits of these devices can be eclipsed by infectious complications. Infection is a very serious and dreadful complication requiring complete removal of the infected device and systemic antimicrobial therapy.2–4 Moreover, the financial cost of managing device infections is enormous. In this article, we review the latest developments pertaining to CIED infections, with a special emphasis on pathogenesis and microbiology. Since their first conceptualization and use in the late 1950s,5 CIEDs have undergone significant enhancements in design and function, and their use continues to rise, with a growing number of indications for placement, improvements in implantation techniques, and enhancements in device programming and monitoring.1 Earlier investigations reported a highly variable CIED infection rate, ranging from 0.13% to 19.9%.6,7 However, a more recent review of case records from the Massachusetts General Hospital reported 21 (1.2%) ICD-related infections among 1700 patients who underwent device implantation procedures.8 In a study by Mela et al,8 CIED infection occurred in 1.8% of 1170 patients who underwent a primary implant, a generator change, …

A cluster of Mycobacterium wolinskyi surgical site infections at an academic medical center.

OBJECTIVE To study a cluster of Mycobacterium wolinskyi surgical site infections (SSIs). DESIGN Observational and case-control study. SETTING Academic hospital. PATIENTS Subjects who developed SSIs with M. wolinskyi following cardiothoracic surgery. METHODS Electronic surveillance was performed for case finding as well as electronic medical record review of infected cases. Surgical procedures were observed. Medical chart review was conducted to identify risk factors. A case-control study was performed to identify risk factors for infection; Fisher exact or Kruskal-Wallis tests were used for comparisons of proportions and medians, respectively. Patient isolates were studied using pulsed-field gel electrophoresis (PFGE). Environmental microbiologic sampling was performed in operating rooms, including high-volume water sampling. RESULTS Six definite cases of M. wolinskyi SSI following cardiothoracic surgery were identified during the outbreak period (October 1, 2008-September 30, 2011). Having cardiac surgery in operating room A was significantly associated with infection (odds ratio, 40; P = .0027). Observational investigation revealed a cold-air blaster exclusive to operating room A as well a microbially contaminated, self-contained water source used in heart-lung machines. The isolates were indistinguishable or closely related by PFGE. No environmental samples were positive for M. wolinskyi. CONCLUSIONS No single point source was established, but 2 potential sources, including a cold-air blaster and a microbially contaminated, self-contained water system used in heart-lung machines for cardiothoracic operations, were identified. Both of these potential sources were removed, and subsequent active surveillance did not reveal any further cases of M. wolinskyi SSI.

Disseminated microsporidiosis in a renal transplant recipient: case report and review of the literature

Microsporidia are opportunistic pathogens that usually cause a limited disease in the gastrointestinal tract. Occasionally, they can cause disseminated disease. In solid organ transplant recipients, disseminated disease has been reported only rarely. We describe a 68‐year‐old woman who presented with fever, cough, and acute kidney injury 6 months after kidney transplantation. Dissemination was confirmed by identification of microsporidial spores in urine and bronchoalveolar lavage fluid. Polymerase chain reaction analysis identified the species as Encephalitozoon cuniculi.

Prosthetic Vascular Graft Infections: A Contemporary Approach to Diagnosis and Management

Improvements in manufacturing and implantation techniques, coupled with an increasing prevalence of atherosclerosis in an aging population, have led to increased utilization of prosthetic vascular grafts. The infection rates of vascular grafts are low. However, when they do occur, high rates of morbidity and mortality can be expected. The purpose of this article is to review the published literature regarding epidemiology, risk factors, pathogenesis, and clinical manifestations of prosthetic vascular graft infections. Moreover, we provide a practical approach to the diagnosis and management of these complicated infections based on empirically grounded evidence.

Usefulness of Sonication of Cardiovascular Implantable Electronic Devices to Enhance Microbial Detection

The cardiovascular implantable electronic device (CIED) infection rate is rising disproportionately to the rate of device implantation. Identification of microorganisms that cause CIED infections is not always achieved using present laboratory techniques. We conducted a prospective study to determine whether device vortexing-sonication followed by culture of the resulting sonicate fluid would enhance microbial detection compared with traditional swab or pocket tissue cultures. Forty-two subjects with noninfected and 35 with infected CIEDs were prospectively enrolled over 12 months. One swab each from the device pocket and device surface, pocket tissue, and the CIED were collected from each patient. Swabs and tissues were cultured using routine methods. The CIED was processed in Ringers solution using vortexing-sonication and the resultant fluid semiquantitatively cultured. Tissue and swab growth was considered significant when colonies grew on ≥2 quadrants of the culture plate and device was considered significant when ≥20 colonies were isolated from 10 ml of sonicate fluid. In noninfected group, 5% of sonicate fluids yielded significant bacterial growth, compared with 5% of tissue cultures (p = 1.00) and 2% of both pocket and device swab cultures (p = 0.317 each). In infected group, significant bacterial growth was observed in 54% of sonicate fluids, significantly greater than the sensitivities of pocket swab (20%, p = 0.001), device swab (9%, p <0.001), or tissue (9%, p <0.001) culture. In conclusion, vortexing-sonication of CIEDs with semiquantitative culture of the resultant sonicate fluid results in a significant increase in the sensitivity of culture results, compared with swab or tissue cultures.

Shiga toxin producing E coli bloodstream infection secondary to Strongyloides penetration through intestinal mucosa.

A 51-year-old woman with diabetes, who immigrated to the USA 22 years ago from Laos, was admitted to the hospital for evaluation of fever, abdominal pain, vomiting and diarrhoea. A workup for acute gastroenteritis revealed a positive stool PCR for Shiga toxin-producing Escherichia coli. Two sets of blood cultures drawn at admission were positive for E coli. A review of her previous medical records revealed the presence of eosinophilia, up to 20%, 14 years prior to that was never investigated. Therefore, stool samples were examined and two of three specimens were positive for Strongyloides stercoralis larvae, confirming the diagnosis of Strongyloides hyperinfection syndrome.