Staphylococcus aureus bacteremia in patients with permanent pacemakers or implantable cardioverter-defibrillators.

BACKGROUND: Although cardiac device infections (CDIs) are a devastating complication of permanent pacemakers or implantable cardioverter-defibrillators, the incidence of CDI in patients with bacteremia is not well defined. The objective of this study was to determine the incidence of CDI among patients with permanent pacemakers or implantable cardioverter-defibrillators who develop Staphylococcus aureus bacteremia (SAB). METHODS AND RESULTS: A cohort of all adult patients with SAB and permanent pacemakers or implantable cardioverter-defibrillators over a 6-year period was evaluated prospectively. The overall incidence of confirmed CDI was 15 of 33 (45.4%). Confirmed CDI occurred in 9 of the 12 patients (75%) with early SAB (<1 year after device placement). Fifteen of 21 patients (71.5%) with late SAB (>/=1 year after device placement) had either confirmed (6 of 21, 28.5%) or possible (9 of 21, 43%) CDI. In 60% of the patients (9 of 15) with confirmed CDI, no local signs or symptoms suggesting generator pocket infection were noted. CONCLUSIONS: The incidence of CDI among patients with SAB and cardiac devices is high. Neither physical examination nor echocardiography can exclude the possibility of CDI. In patients with early SAB, the device is usually involved, and approximately 40% of these patients have obvious clinical signs of cardiac device involvement. Conversely, in patients with late SAB, the cardiac device is rarely the initial source of bacteremia, and there is a paucity of local signs of device involvement. The cardiac device is involved, however, in >/=28% of these patients.

Outcomes of an antimicrobial control program in a teaching hospital.

The clinical outcomes and cost-effectiveness of an antimicrobial control program (ACP) were studied. The impact of an ACP in a teaching hospital was analyzed by comparing clinical outcomes and intravenous antimicrobial costs over two two-year periods, the two years before the program and the first two years after the program's inception. Admission baseline data, length of stay, mortality, and readmission rates were gathered for each patient. Patients were identified by using the International Classification of Diseases. Multivariate logistic regression models were constructed for mortality and for lengths of stay of 12 or more days. The acquisition costs of intravenous antimicrobial agents for the second baseline year and the entire program period were tabulated and compared. The average daily inpatient census was determined. The ACP was associated with a 2.4-day decrease in length of stay and a reduction in mortality from 8.28% to 6.61%. Rates of readmission for infection within 30 days of discharge remained about the same. Inpatient pharmacy costs other than intravenous antimicrobials decreased an average of only 5.7% over the two program years, but the acquisition cost of intravenous antimicrobials for both program years yielded a total cost saving of $291,885, a reduction of 30.8%. The institution's average daily census fell 19% between the second baseline year and the second program year. An ACP directed by a clinical pharmacist trained in infectious diseases was associated with improvements in inpatient length of stay and mortality. The ACP decreased intravenous antimicrobial costs and facilitated the approval process for restricted and nonformulary antimicrobial agents.

Causes and consequences of discontinuation of the implantable cardioverter-defibrillator therapy in non-terminally ill patients.

Infection and implantable cardioverter-defibrillator shocks are important contributing factors to discontinuation of cardioverter-defibrillator therapy in non-terminally ill patients. These patients are at a high risk of sudden cardiac death despite continued antiarrhythmic drug therapy.

Transient data stream dissociation in computerized data acquisition system masquerading as a sensing abnormality.

During testing of a CPI model 1715 ICD, an apparent sensing abnormality was noted following shock delivery for VF. Close inspection of the recording prior to the defibrillation attempt revealed that the surface leads spontaneously lost 848 ms of data while the event marker was unaffected. Computer simulations revealed that an inadequate buffer size for the amplified (surface ECG) data was the likely source of data loss. It is important to recognize that a discordance between surface leads and event marker may represent an abnormality in the data acquisition system and simulate an ICD or lead malfunction.

Safety of slow pathway ablation in patients with long PR interval: further evidence of fast and slow pathway interaction.

Whether the presence of abnormal PR before selective slow pathway ablation for AV node reentrant tachycardia increased the risk of complete heart block remains controversial. We report our experience in seven patients with prolonged PR intervals undergoing catheter ablation for AV reentry tachycardia. Their mean age was 66 +/- 12 years; four patients were female and three were male. RF ablation was performed using an anatomically guided stepwise approach. In six patients, common type AV node reentry was induced and uncommon type was observed in the remaining patient. In all seven patients, successful selective slow pathway ablation was associated with no occurrence of complete heart block and was followed by shortening of the AH interval in five patients. In all seven patients, successful ablation was achieved at anterior sites (M1 in two patients and M2 in five patients). Despite AH shortening after ablation, the 1:1 AV conduction was prolonged after elimination of the slow pathway, excluding either sympathetic tone activation or parasympathetic denervation. In conclusion, selective slow pathway ablation can be performed safely in the majority of patients with prolonged PR interval before the procedure. Because successful ablation is achieved at anterior sites in most patients, careful selection and monitoring of catheter position is required.

Interactions between transvenous nonthoracotomy cardioverter defibrillator systems and permanent transvenous endocardial pacemakers.

Limited information is available regarding potential adverse interactions between transvenous nonthoracotomy cardioverter defibrillators and pacemakers. We describe our experience with 37 patients who have undergone successful implantation of both a transvenous defibrillator and pacemaker. The patients' mean age was 64 +/- 12.9 years. Thirty-three were male and four were female. The mean LVEF was 30.8% +/- 11.8%. The indications for pacemaker implantation included sick sinus syndrome in 13 patients, complete heart block in 15 patients, sinus bradycardia secondary to medications in 8 patients, and neurocardiogenic syncope in 1 patient. The indications for insertion of a defibrillator included medically refractory VT in 27 patients and sudden cardiac death in 10 patients. Twenty-three patients received an Endotak lead and 14 patients received a Transvene lead. Eighteen patients had a pacemaker prior to an ICD, 14 patients had an ICD prior to a pacemaker, and 4 patients had both devices placed simultaneously. Interaction was evaluated at implant of the second device and 1-3 days after both devices were placed. Detection of VF/VT was analyzed during asynchronous pacing (DOO/VOO) with maximum pacing output. In addition, in six patients, DFT was determined before and after pacemaker implantation. In 14 patients (38%), device interactions that could not always be optimally corrected were observed. In five patients, the pacemaker was reset to the "noise reversion" mode after high energy ICD discharge. Oversensing of atrial pacemaker stimuli resulted in inappropriate ICD firings in four patients. This was observed only with a specific device and could not be prevented by atrial lead repositioning in two of them, but required reprogramming of the pacemaker to the VVI mode. An increase in DFT was observed in five patients who had a pacemaker implanted after an ICD. Compared with previously published studies, a greater frequency of transvenous ICD and pacemaker interactions were observed. Considering that almost 50% of the patients already have a pacemaker at the time of ICD implant, the availability of defibrillators with dual chamber pacing capability will not eliminate the potential for this problem.

Evaluation of the effect of transthoracic cardioversion from ventricular tachycardia to sinus rhythm on left atrial mechanical function.

We measured left atrial function during sinus rhythm before and after ventricular tachycardia was induced in an electrophysiology laboratory, using peak transmitral A-wave velocity from pulsed-Doppler transthoracic echocardiography as a marker of left atrial mechanical function. The results of this prospective study do not support the hypothesis that a transthoracic shock of mild to moderate energy diminishes atrial mechanical function.

Protozoal colonization of the intestinal tract in institutionalized Romanian children.

To determine the prevalence of intestinal parasitic infections in 92 Romanian children institutionalized at Colentina Hospital (Bucharest, Romania) and at the Dystrophic Center (Vidra, Romania), medical charts were reviewed and complete physical examinations were performed. The nutritional status of each child was evaluated, and their sera were tested for the presence of antibodies to human immunodeficiency virus (HIV) and Cryptosporidium. Fecal samples were collected in 10% formalin and examined by an immunofluorescent assay and by trichrome staining for intestinal parasites. At least one protozoan was identified in 77% of the fecal specimens examined. Giardia lamblia (72% of cases), Cryptosporidium parvum (12%), and Entamoeba coli (4%) were the only parasites identified. Stepwise logistic regression revealed that the only factors predictive of giardia colonization were normal nutritional status (P < .01) and HIV seropositivity (P < .02), while cryptosporidium colonization was only associated with where the children lived (P < .01). Seventy-three percent of the children had IgA and/or IgG antibodies to Cryptosporidium in their sera. The presence of these antibodies was strongly associated with the severity of symptoms present in the HIV-infected children (P < .01). Protozoal colonization of the intestinal tract is common in institutionalized Romanian children and may play a role in causing morbidity and mortality in this high-risk group of children.

Treatment of lymphocutaneous and visceral sporotrichosis with fluconazole.

Thirty patients with documented sporotrichosis were treated with 200-800 mg of fluconazole daily. Fourteen patients had lymphocutaneous infection; only five (36%) of these patients had any underlying illnesses. Sixteen patients had osteoarticular or visceral sporotrichosis; 12 (75%) of these patients had underlying diseases, mostly alcoholism, diabetes mellitus, and chronic obstructive pulmonary disease. Eleven of the 30 patients had relapsed after prior antifungal therapy. Most patients were treated with 400 mg of fluconazole; however, four received 200 mg of fluconazole daily for the entire course, and four received 800 mg of fluconazole daily for a portion of their therapy or for the entire course of therapy. Fluconazole therapy cured 10 (71%) of 14 patients with lymphocutaneous sporotrichosis. However, only five (31%) of 16 patients with osteoarticular or visceral sporotrichosis responded to therapy; the conditions of two of these five patients improved only, and there was no documented cure of their infections. With the exception of alopecia in five patients, toxic effects were minimal. Fluconazole is only modestly effective for treatment of sporotrichosis and should be considered second-line therapy for the occasional patient who is unable to take itraconazole.

A Cryptosporidium parvum genomic region encoding hemolytic activity.

Successful parasitization by Cryptosporidium parvum requires multiple disruptions in both host and protozoan cell membranes as cryptosporidial sporozoites invade intestinal epithelial cells and subsequently develop into asexual and sexual life stages. To identify cryptosporidial proteins which may play a role in these membrane alterations, hemolytic activity was used as a marker to screen a C. parvum genomic expression library. A stable hemolytic clone (H4) containing a 5.5-kb cryptosporidial genomic fragment was identified. The hemolytic activity encoded on H4 was mapped to a 1-kb region that contained a complete 690-bp open reading frame (hemA) ending in a common stop codon. A 21-kDa plasmid-encoded recombinant protein was expressed in maxicells containing H4. Subclones of H4 which contained only a portion of hemA did not induce hemolysis on blood agar or promote expression of the recombinant protein in maxicells. Reverse transcriptase-mediated PCR analysis of total RNA isolated from excysted sporozoites and the intestines of infected adult mice with severe combined immunodeficiency demonstrated that hemA is actively transcribed during the cryptosporidial life cycle.

Enteral human serum immunoglobulin treatment of cryptosporidiosis in mice with severe combined immunodeficiency.

The anti-cryptosporidial immunoglobulin G antibodies in two commercially available human serum immunoglobulin (HSIG) products were quantified and characterized. The mean level of Cryptosporidium parvum-specific immunoglobulin G in HSIG was eightfold higher than the antibody level found in the sera of three immunocompetent individuals convalescing from cryptosporidiosis. However, HSIG products displayed no reactivity to cryptosporidial antigens in immunoblot analyses, while convalescent-phase sera demonstrated characteristic banding patterns. When HSIG was given to newborn severe combined immunodeficiency (scid) mice before and shortly after experimental infection, a decreased intensity of infection was observed in the intestines of the mice compared with that of control mice. However, there was no difference in mortality or histopathologic findings in the intestines of HSIG-treated and control mice when treatment was not started until 22 days of age. These results indicate that HSIG may be beneficial when given prophylactically; however, HSIG cannot eradicate cryptosporidia from mucosal surfaces in an established infection.

Apophysomyces elegans infection in a renal transplant recipient.

A 50-year-old cadaveric renal transplant recipient on immunosuppressive therapy is described with post-traumatic cutaneous infection caused by Apophysomyces elegans. He showed no evidence of hematogenous dissemination and recovered fully after therapy with extensive local debridement and amphotericin B lipid complex. An apparent drug-drug interaction between amphotericin B lipid complex and cyclosporine was encountered. The course of A elegans infection in transplant recipients may be similar to that described in immunocompetent hosts. A elegans infection should be considered in evaluation of post-traumatic cutaneous infection not readily responsive to antibacterial therapy.

Inability of interferon-gamma and aminoguanidine to alter Cryptosporidium parvum infection in mice with severe combined immunodeficiency.

Severe combined immunodeficiency (scid) mice have been useful in identifying specific host defense systems responsible for containing and eradicating Cryptosporidium parvum infection. Adult scid mice were given C. parvum oocysts and treated weekly with monoclonal antimurine interferon-gamma (anti-IFN-gamma). Anti-IFN-gamma-treated mice had more cryptosporidia seen in the intestines and had more severe morphologic changes associated with disease than control mice. To assess the mechanism of this effect, infected adult BALB/c and scid mice were treated with the nitric oxide synthase inhibitor, aminoguanidine. Infection in aminoguanidine-treated mice was not significantly different from that in control mice. Next, the effects of pharmacologic doses of IFN-gamma (10,000 IU) on the course of cryptosporidiosis in newborn scid mice were evaluated. IFN-gamma did not reverse the initial susceptibility of neonatal scid mice to cryptosporidiosis and continued treatment with IFN-gamma (10,000 IU weekly) did not alter survival. We conclude that IFN-gamma does not exert its anticryptosporidial effect by stimulation of nitric oxide production. Deficient IFN-gamma production by neonatal lymphocytes does not appear to be responsible for the increased severity of infection observed in neonatal animals. Also, IFN-gamma may not be useful in treating immunocompromised patients with cryptosporidiosis.

Evaluation of outpatients experiencing implantable cardioverter defibrillator shocks associated with minimal symptoms.

Patients receiving minimally symptomatic shocks from their implantable cardioverter defibrillators were studied prospectively using transtelephonic ECG loop monitoring. The time course to the first subsequent shock was evaluated. Twenty-nine consecutive patients who received a shock preceded by mild palpitations or no symptoms were given a transtelephonic ECG loop monitor and instructed to activate the monitor if a subsequent shock occurred. Kaplan-Meier analysis was used to quantitate the time to first shock during the study period. The point estimate +/- standard error of patients receiving a shock during the study period was 31% +/- 9% at 30 days, 41% +/- 9% at 60 days, and 60% +/- 9% at 120 days. The ECG was successfully transmitted in 7 of 13 patients who had shocks in the 60-day monitoring period, and demonstrated inappropriate shocks in 6 of 7. Determination of the cause of shock led to a change in subsequent management in all 7 patients. We conclude that the incidence of inappropriate shocks may be higher than estimated previously in patients with minimal symptoms prior to the shock. There are thousands of patients with implantable cardioverter defibrillators that have no storage function for treated tachycardias; transtelephonic ECG loop monitoring can determine the cause of implantable cardioverter defibrillator discharge in these patients, and the diagnosis is invaluable in their management.

Rhodococcus equi infections of humans. 12 cases and a review of the literature.

Increased recognition of Rhodococcus equi as a human pathogen has occurred since 1983, when the first review article summarized the world's literature of 12 cases. In this article, we present 12 cases from the University of Oklahoma Health Sciences Center and review 60 from the literature. Most cases occur in immunocompromised hosts and present as chronic cavitary pneumonias. Associated extrapulmonary disease is seen at diagnosis in 7% of patients with pneumonia, and relapse occurs at extrapulmonary sites in 13%, often without reappearance of pulmonary disease. Relapse may follow a course of antimicrobial therapy that is too brief, but can also occur during treatment. Infections also occur in the gastrointestinal tract, causing enteritis and regional adenitis with abscesses. Contaminated wounds may become infected. Isolated bacteremias may be a manifestation of latent infection recurring during a period of immune suppression. A common feature of human R. equi infection is delay in diagnosis. The insidious course of disease contributes to delay, as does failure to identify the organism. R. equi is easily cultured on nonselective media but commonly mistaken for a diphtheroid or occasionally for a mycobacterium based on acid-fast appearance. Form and duration of treatment are closely related to host immune status. Immunocompromised patients require prolonged or indefinite therapy with multiple antibiotics. Infections in immunocompetent hosts are easily treated with short courses of single agents. Infections related to contaminated wounds are treated primarily by irrigation and debridement. Infections in immunocompromised hosts are increasing in frequency largely due the AIDS epidemic. Infections in immunocompetent hosts, reported rarely before this series, may be underdiagnosed, perhaps because R. equi resembles common commensals and has limited virulence in this population. This report demonstrates that R. equi infections, including community-acquired pneumonias, occur in immunocompetent hosts.

Catheter ablation of sinoatrial node reentrant tachycardia.

OBJECTIVES: This study evaluates 1) the safety and efficacy of catheter delivery of radiofrequency current to eliminate sustained sinoatrial node reentrant tachycardia; 2) the incidence of sinoatrial node reentrant tachycardia in the current group of patients undergoing electrophysiologic study for paroxysmal supraventricular tachycardia; and 3) the association of sinoatrial node reentrant tachycardia with other tachyarrhythmias. BACKGROUND: Sustained sinoatrial node reentrant tachycardia is an uncommon cause of paroxysmal supraventricular tachycardia that is reported to occur infrequently in conjunction with other arrhythmias. Although pharmacologic and surgical therapies are available, there is limited information with regard to catheter ablation of sinoatrial node reentrant tachycardia. METHODS: Ten patients with sustained sinoatrial node reentrant tachycardia underwent electrophysiologic study and radiofrequency current ablation. Patients were followed up for 9.2 +/- 6.0 months. RESULTS: Of 343 consecutive patients referred for electrophysiologic evaluation of paroxysmal supraventricular tachycardia, 11 (3.2%) were found to have inducible sustained sinoatrial node reentrant tachycardia. Nine of the 11 patients had other associated arrhythmias, including atrioventricular (AV) node reentrant tachycardia (6 patients), AV reciprocating tachycardia (2 patients), ectopic atrial tachycardia (2 patients) and bundle branch reentrant tachycardia (1 patient). In 10 patients, direct ablation of sinoatrial node reentrant tachycardia was attempted and was successful in all (confidence interval for failure 0-0.26). Sinoatrial node reentrant tachycardia was eliminated with a median of four radiofrequency current applications (range 1 to 10) at 20 to 30 W. Successful ablation site characteristics during sinoatrial node reentrant tachycardia included 1) atrial activation > or = 35 ms (mean 44 +/- 8 ms) before the onset of the surface P wave, 2) atrial activation > or = 20 ms (mean 28 +/- 6 ms) before the onset of high right atrial activation, and 3) significantly prolonged and fractionated electrograms (mean duration 87 +/- 21 ms). No complications were encountered, and there have been no recurrences of sinoatrial node reentrant tachycardia. CONCLUSIONS: Sinoatrial node reentrant tachycardia may be effectively and safely treated with radiofrequency current ablation at the site of earliest atrial activation.