George M. Viola

Rapidly growing mycobacterial bloodstream infections

About 20 species of rapidly growing mycobacteria species that are capable of infecting human beings and causing bloodstream infections have been identified. Many more of these species are being discovered worldwide, especially in resource-poor settings. These microorganisms have been known to cause outbreaks and pseudo-outbreaks. Although rapidly growing mycobacteria are not highly virulent or life threatening, they have a high predisposition to create biofilms and to colonise and infect intravascular catheters. Early detection and identification of specific species can help to estimate predictable antimicrobial susceptibility patterns. However, because susceptibility data originate from developed countries, studies in resource-poor settings urgently need to be done. The best outcome of cure without recurrence depends on a combination of at least 4 weeks of treatment with two or more active antimicrobial agents, plus removal of the intravascular catheter. We review and discuss the epidemiology, pathogenesis, diagnosis, management, and outcomes of rapidly growing mycobacterial bloodstream infections.

Norovirus gastroenteritis successfully treated with nitazoxanide.

Infectious diarrhea is a common occurrence in the immunosuppressed population. We present a 43-year-old individual with large-volume stool output Norovirus acute gastroenteritis in the setting of relapsed refractory acute myelogenous leukemia, hematopoietic stem cell transplantation, and biopsy-proven cutaneous and pulmonary graft-versus-host disease. Therapeutic options such as intravenous immunoglobulin or reduction of immunosuppressants were not a feasible choice. A prompt clinical cure was achieved with nitazoxanide, a broad-spectrum antimicrobial agent. Nitazoxanide may be a safe therapeutic alternative, in which a reduction in immunosuppression may not be a viable option.

Nonstaphylococcal Infections of Cardiac Implantable Electronic Devices

Background— Along with the rising use of cardiac implantable electronic devices (CIEDs), there has been a disproportional increase in the number of infections of such devices. Little is known about nonstaphylococcal CIED-related infections, which make up ≈10% to 30% of all CIED infections. Methods and Results— A retrospective review of hospital records of patients admitted with a CIED-related infection was conducted in 4 academic hospitals in Houston, Tex, between 2002 and 2009. Of the 504 identified patients with CIED-related infection, 80 (16%) had a nonstaphylococcal infection and were the focus of this study. The mean duration of CIED placement before infection was 109±27 weeks, whereas 44% had their device previously manipulated within a mean of 29.5±6 weeks. The mean duration of clinical symptoms before admission was 48±12.8 days. Furthermore, 13 patients (16%) presented with CIED-related endocarditis. Although not described in prior reports, we identified 3 definite and 2 suspected cases of secondary Gram-negative bacteria seeding of the CIED. Inappropriate antimicrobial coverage was provided in ≈50% of the cases with a mean period of 2.1 days. The overall mortality rate was 4%. Conclusions— Nonstaphylococcal CIED-related infections are prevalent and diverse with a relatively low virulence and mortality rate. Because nonstaphylococcal organisms are capable of secondarily seeding the CIED, a high suspicion for CIED-related infection is warranted in patients with bloodstream infection. In patients with suspected CIED infection, adequate Gram-positive and Gram-negative antibacterial coverage should be administered until microbiological data become available.

Management of rapidly growing mycobacterial bacteremia in cancer patients

Rapidly growing mycobacteria (RGM) are environmental organisms capable of causing a wide spectrum of diseases. We identified 116 cancer patients with RGM. Mycobacterium mucogenicum was the leading cause of disease. Removal of the catheter correlated with significant decrease in the bacteremia relapse rate (P = .007). A median duration of 4 weeks of therapy produced a good outcome.

Breast Tissue Expander—Related Infections: Perioperative Antimicrobial Regimens

OBJECTIVE The rate of postmastectomy tissue expander (TE) infection remains excessively high, ranging between 2% and 24%. We hypothesized that current perioperative antimicrobial regimens utilized for breast TE reconstruction may be outdated as a result of recent changes in microflora and susceptibility patterns. DESIGN AND METHODS We reviewed the records of all patients who had a TE reconstructive procedure and developed a definite breast TE infection between 2003 and 2010 at MD Anderson Cancer Center. Antimicrobials were stratified into 3 groups: systemic perioperative, local irrigation, and oral immediate postoperative antimicrobials. These were considered discordant if they did not target the isolated organisms, while a breakthrough infection was defined as an infection that occurred despite concordant antimicrobial coverage. RESULTS Overall, 75 patients with a definite TE infection were identified. The most common organisms identified were methicillin-resistant Staphylococcus epidermidis (29%), methicillin-resistant Staphylococcus aureus (15%), and gram-negative rods (26%). The use of systemic perioperative antimicrobials was deemed discordant in 51% of the cases. Although 79% of the patients received broad-spectrum perioperative local antimicrobial irrigation, 63% developed a breakthrough infection. Even though 61% received oral postoperative prophylactic antimicrobials, 63% of the times they were deemed discordant. CONCLUSIONS Contrary to the proven effectiveness of a single dose of perioperative antibiotics, the common use of local antimicrobial irrigation and prolonged postoperative oral antibiotics appears to be an inadequate component of our preventive armamentarium. Also, because methicillin-resistant staphylococcal and pseudomonal infections occurred approximately 60% of the time, at institutions that have observed an increase of these organisms, it may be prudent that perioperative antimicrobials target these microorganisms.

Successful Salvage of Central Venous Catheters in Patients with Catheter-Related or Central Line-Associated Bloodstream Infections by Using a Catheter Lock Solution Consisting of Minocycline, EDTA, and 25% Ethanol

ABSTRACT In cancer patients with long-term central venous catheters (CVC), removal and reinsertion of a new CVC at a different site might be difficult because of the unavailability of accessible vascular sites. In vitro and animal studies showed that a minocycline-EDTA-ethanol (M-EDTA-EtOH) lock solution may eradicate microbial organisms in biofilms, hence enabling the treatment of central line-associated bloodstream infections (CLABSI) while retaining the catheter in situ. Between April 2013 and July 2014, we enrolled 30 patients with CLABSI in a prospective study and compared them to a historical group of 60 patients with CLABSI who had their CVC removed and a new CVC inserted. Each catheter lumen was locked with an M-EDTA-EtOH solution for 2 h administered once daily, for a total of 7 doses. Patients who received locks had clinical characteristics that were comparable to those of the control group. The times to fever resolution and microbiological eradication were similar in the two groups. Patients with the lock intervention received a shorter duration of systemic antibiotic therapy than that of the control patients (median, 11 days versus 16 days, respectively; P < 0.0001), and they were able to retain their CVCs for a median of 74 days after the onset of bacteremia. The M-EDTA-EtOH lock was associated with a significantly decreased rate of mechanical and infectious complications compared to that of the CVC removal/reinsertion group, who received a longer duration of systemic antimicrobial therapy. (This study has been registered at ClinicalTrials.gov under registration no. NCT01539343.)

Infections of cardiac implantable electronic devices: A retrospective multicenter observational study

Infections of cardiac implantable electronic devices (CIED) can cause significant morbidity, mortality, and financial burden. Although staphylococcal organisms account for most infections of these cardiac devices, approximately 20% of all CIED-related infections are caused by non-Staphylococcus species. Herein we describe and compare the demographics, clinical presentation, and outcomes of Staphylococcus aureus and non-staphylococcal infections of CIED. We performed a retrospective, multicenter, observational study of patients from 4 academic hospitals in Houston between 2002 and 2009. All 80 identified non-staphylococcal CIED-related infections were matched, at a 1:1 ratio, to S. aureus infections. Although the demographics and general comorbidities in the 2 study groups were relatively similar, the S. aureus group had a higher proportion of patients with coronary artery disease, diabetes mellitus, and end-stage renal disease. Additionally, 81% of S. aureus compared with only 48.5% of the non-staphylococcal CIED-related infections were health care-associated (p < 0.001). Furthermore, when compared to non-staphylococcal infections, the S. aureus group had more indwelling intravascular foreign material (p < 0.001), more rapid clinical progression (p < 0.001), and overall worse clinical presentation (p < 0.001). However, after stratifying by clinical presentation, the mortality rates in the 2 groups were similar (p = 0.45). Since approximately one-fifth of all CIED-related infections are caused by non-staphylococcal organisms, and untimely antibiotic treatment can result in serious complications, it may be prudent to broaden empiric antimicrobial therapy to cover both Gram-positive and -negative bacteria, until the causative organism is identified. AbbreviationsCIED = cardiac implantable electronic devices, ESR = erythrocyte sedimentation rate, ICD = implantable cardioverter-defibrillators, MRSA = methicillin-resistant Staphylococcus aureus, MSSA = methicillin-sensitive Staphylococcus aureus, PPM = permanent pacemakers, TEE = transesophageal echocardiogram, TTE = transthoracic echocardiogram, WBC = white blood cell count

Incubation Alone Is Adequate as a Culturing Technique for Cardiac Rhythm Management Devices

ABSTRACT There exist no standardized methods for culturing cardiac rhythm management devices. To identify the most optimal culturing method, we compared various techniques that comprise vortex, sonication, and incubation or combinations thereof. Incubation alone yielded bacterial colony counts similar to those of other culturing combinations and is the least labor-intensive.

Improving Antimicrobial Regimens for the Treatment of Breast Tissue Expander-Related Infections.

Background: Infectious complications in tissue expander (TE) breast reconstruction can be devastating and costly. Therefore, to optimize care, we examined patient’s demographics, microbiology of TE infections, and the efficacy of empiric antimicrobial regimens and thereafter generated an algorithm for the treatment of these complex infections. Methods: We retrospectively reviewed all patients who underwent TE breast reconstruction between 2003 and 2012 and analyzed those patients who developed a “definite” device-related infection leading to TE explantation and had a positive intraoperative culture. Results: A total of 3,082 patients underwent immediate breast reconstruction with TE. Of these, 378 patients (12.3%) developed an infection, 189 (6.1%) eventually proceed with explantation, and 118 (3.8%) had a positive intraoperative culture. Gram-positive organisms caused 73% of infections, and Gram-negative organisms caused 27% of infections. Narrow-spectrum empiric antimicrobials with predominantly Gram-positive coverage were deemed appropriate in only 62% of cases, and those with Gram-negative coverage were appropriate in 46%. Broad-spectrum antimicrobials were used in 47% of cases, mainly recommended by infectious disease specialists, and were considered appropriate in >90% of the occasions. Conclusions: Current empiric antibiotic regimens do not cover the vast spectrum of organisms causing TE infections. To increase the salvage rate of an infected TE, at the first sign of infection, in addition to benefiting with an infectious diseases consultation, empiric coverage with broad-spectrum antibiotics active against biofilm-embedded organisms should be administered.

Cardiovascular Implantable Device Infections

As life expectancy continues to increase and biotechnology advances, the use of cardiovascular implantable devices will continue to rise. Unfortunately, despite modern medical advances, the infection and mortality rates remain excessively elevated. This article reviews the pathophysiology and general concepts of cardiac device–related infections, including the physical and chemical characteristics of the medical device, host response to the medical device, and the microbiologic virulence factors. Infections of the most commonly utilized cardiovascular implantable devices, including cardiovascular implantable electronic devices, bioprosthetic and mechanical valves, ventricular assist devices, total artificial hearts, and coronary artery stents, are reviewed in detail.