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.

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.

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.

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.

Effect of abrogation of natural killer cell activity on the course of candidiasis induced by intraperitoneal administration and gastrointestinal candidiasis in mice with severe combined immunodeficiency

Candida albicans CFU per gram of tissue recovered from livers, spleens, and kidneys of 12 severe combined immunodeficiency (scid) and 12 BALB/c mice 5 days after intraperitoneal (i.p.) administration of 10(7) C. albicans cells were not significantly different. Nine scid mice given normal rabbit serum (NRS) as a control and eight scid mice given anti-asialo-GM1 (alpha-ASGM1) had C. albicans CFU per gram recovered from livers and spleens 1 week after i.p. administration of C. albicans that were not significantly different, despite virtual elimination of natural killer (NK) cell activity in mice treated with alpha-ASGM1. At 2 weeks after i.p. administration, despite significantly increased NK cell activity in eight infected NRS-treated scid mice and virtual elimination of NK cell activity by alpha-ASGM1 treatment of eight scid mice, C. albicans CFU per gram recovered from livers and kidneys were not significantly different. At 2 weeks after intragastric administration of 2 x 10(6) C. albicans cells, eight NRS- and eight alpha-ASGM1-treated scid mice had identical proportions colonized with C. albicans and similar C. albicans CFU per gram recovered from feces. There was no evidence of hematogenous dissemination in either group. Similar results were seen 1 week after intragastric administration of 10(7) C. albicans cells. We conclude that NK cell activity is increased by i.p. administration of C. albicans in scid mice, but nontheless, abrogation of NK cell activity is not associated with enhanced susceptibility to candidiasis induced by i.p. administration and also is not associated with enhanced susceptibility to gastrointestinal colonization or hematogenous dissemination after intragastric administration of C. albicans.

Cryptosporidium parvum infection after abrogation of natural killer cell activity in normal and severe combined immunodeficiency mice

The role of natural killer (NK) cell activity in adult mice with severe combined immunodeficiency (scid mice) infected with Cryptosporidium parvum oocytes was evaluated. Adult BALB/c and scid mice were inoculated intragastrically with 10(6) C. parvum oocysts after the administration of anti-asialo-GM1 or control normal rabbit serum. Groups of animals were evaluated for splenic NK cell activity and examined histopathologically at 2, 4, and 6 wk postinfection. Virtual elimination of splenic NK cell activity by anti-asialo-GM1 treatment was demonstrated. Nonetheless, no differences in the occurrence of illness, death, or histopathologic evidence of infection were observed between anti-asialo-GM1-treated and control-treated BALB/c or scid mice. We conclude that NK cell activity, at least as measured in the spleen, does not play a significant role in murine host defense of cryptosporidial infection, even in the absence of functional B and T cells.

Symposium on antimicrobial therapy. VII. The fluoroquinolones

The fluoroquinolones represent an important addition to the antimicrobial armamentarium. They are, however, commonly overused. It is estimated that in 1989, ciprofloxacin was prescribed for 1 in every 44 Americans. This observation demonstrates not only the overusage, but the economic incentive for development of additional fluoroquinolones. In some situations, oral fluoroquinolone therapy can reduce costs by eliminating the need for parenteral therapy and reducing the need for or the duration of hospitalization. In most situations where oral antimicrobial agents are being considered, however, the fluoroquinolones are among the most expensive alternatives. In addition to concerns about cost factors, it is important to reiterate concern that widespread overuse of these agents will promote the development of microbial resistance and ultimately limit their usefulness. The clinical usefulness of the fluoroquinolones is summarized in Table 4. As can be seen, the fluoroquinolones are the "possibly preferred agent" in very few infections: complicated urinary tract infections due to Gram-negative bacilli resistant to other oral antimicrobial agents, severe bacterial gastroenteritis, exacerbations of lower respiratory tract infection in patients with cystic fibrosis, osteomyelitis due to Gram-negative bacilli sensitive to the fluoroquinolones, and invasive external otitis. They are alternative agents in a number of other infections when sensitive Gram-negative bacilli are the identified pathogens. A considerable literature exists on using these agents in these and other circumstances, but one must remain wary of limited reports of efficacy in comparison to known efficacy of established and less expensive agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastric colonization with Candida albicans

We adapted a rat model of gastrointestinal candidiasis for studies of in vivo gastric colonization with Candida albicans. Whereas normal rats cleared a single intragastric inoculum of 5 x 10(6) C. albicans from the stomach within 4 hours, rats pretreated with chloramphenicol and gentamicin achieved stable gastric colonization for at least 5 days after administration of this inoculum. We next used this model to study host modifications hypothesized to alter gastric colonization. A first group received dilute HCl 4 hr before yeast inoculation, to induce acute superficial gastric erosions; another group was treated with glucocorticosteroid beginning 12 days before yeast inoculation; and another group received famotidine therapy beginning 3 days before yeast inoculation, to neutralize gastric acidity. Recovery of yeasts from stomachs was significantly different from the control group only in rats treated with steroids; greater colonization was found in the rats so treated. In a final group of experiments, we attempted to inhibit in vivo gastric colonization with yeasts by preincubation of yeasts in vitro with a polyclonal antiserum raised in rabbits against heat-killed C. albicans. We were not able to demonstrate inhibition of gastric colonization by preincubation with this antiserum in this model system.

Clinical experience with HIV-infected patients at the University of Oklahoma Health Sciences Center: an update

We reviewed the course of 545 human immunodeficiency virus (HIV)-infected patients seen between 1983 and March 30, 1991. A majority were Caucasian homosexual or bisexual men, while parenteral drug abusers represented a smaller proportion than seen nationwide. In the 274 patients with the acquired immunodeficiency syndrome (AIDS), the distribution of AIDS-defining conditions was generally consistent with those reported in studies from elsewhere in the United States. However, toxoplasmosis remained relatively uncommon. There was a slightly higher incidence of disseminated histoplasmosis compared to other studies. HIV encephalopathy (AIDS dementia) was likely underdiagnosed. Although data suggested prolongation of the asymptomatic phase of HIV infection, median survival after AIDS diagnosis remained approximately 12 months.

Symposium on antimicrobial therapy. IV. The cephalosporins

Hopefully this review has brought some cephalosporin contentment to replace cephalosporin confusion. From the classification of these antibiotics in Table 1, we have made some significant reductions. One should know how to use cefazolin for staphylococcal/streptococcal infections and for surgical prophylaxis. One should know that cephalexin is massively overused, and really now not all that useful an agent. Cefuroxime is a useful agent for beta-lactamase producing H. influenzae infections. Cefotetan has a role in surgical prophylaxis in ob/gyn and represents the best antianaerobic activity of the cephalosporins; although no cephalosporin is a primary drug for anaerobic infections. Cefuroxime axetil or cefprozil can be useful for comparatively minor infections due to beta-lactamase producing H. influenzae. A third generation cephalosporin represents a reasonable alternative, in certain situations, to aminoglycoside therapy for infections due to multiply drug-resistant Gram-negative bacilli. Ceftazidime is an alternative antipseudomonal beta-lactam antibiotic. Despite the lack of indications for use of cephalosporins as drugs of choice, rational use of these agents can provide safe, effective, and efficient therapy for a variety of infectious diseases. They will likely remain an important part of the physicians' antimicrobial armamentarium for the foreseeable future.

Treatment of supraventricular tachycardias with transcatheter delivery of radiofrequency current

Medical therapy for the treatment of supraventricular tachycardias is frequently ineffective and associated with significant side effects, whereas curative surgical approaches have generally been limited by their considerable morbidity and cost. Greater understanding of the mechanisms underlying supraventricular tachycardias has improved our ability to precisely map endocardial areas critical to arrhythmogenesis. Advances in catheter ablation techniques and particularly the use of radiofrequency current to generate thermal energy for ablation have resulted in dramatic success rates for curative catheter ablation. This review examines the physics of radiofrequency current ablation and its application to the treatment of atrial fibrillation, atrial flutter, AV nodal reentrant tachycardia, and arrhythmias associated with the Wolff-Parkinson-White syndrome. The limitations, risks, and cost-effectiveness of this technique relative to medical and surgical approaches are also evaluated.

Cryptosporidiosis in adult and neonatal mice with severe combined immunodeficiency

Cryptosporidium parvum causes protracted diarrhoea in immunodeficient hosts. To characterize the role that T and B lymphocytes play in the eradication of the parasite from the intestinal mucosa, the course of infection in mice with severe combined immunodeficiency (SCID) was studied. Twenty-nine SCID and 26 BALB/c adult mice received 10(6) oocysts intragastrically. The course of infection in the two strains was similar until 2 months after inoculation, when moderate numbers of organisms were identified in the villous and crypt mucosa of the ileum and proximal colon of SCID mice. Three months after inoculation, SCID mice developed wasting and progressive intestinal and biliary tract disease. At 5 months, mortality of 72 and 0 per cent, respectively, was observed in the SCID and BALB/c mice. Twenty-four SCID and 26 BALB/c neonatal mice were also inoculated with C. parvum. Cryptosporidiosis occurred in SCID and BALB/c mice within 2 weeks of inoculation. Subsequently, BALB/c, but not SCID mice, eradicated the parasite from their intestinal mucosa. SCID mice developed progressively severe cryptosporidiosis which killed all animals within 7 weeks. Responses mediated by B or T cells, or both, appeared to play a role in eradicating C. parvum from the intestinal mucosa, since SCID mice were more severely affected than BALB/c mice. The different course of infection in adult and neonatal SCID mice indicated that other age-related factors also played a role in containing C. parvum infection.

A controlled trial of fluconazole to prevent fungal infections in patients undergoing bone marrow transplantation

BACKGROUND AND METHODS

Superficial and systemic fungal infections are a major problem among severely immunocompromised patients who undergo bone marrow transplantation. We performed a double-blind, randomized, multicenter trial in which patients receiving bone marrow transplants were randomly assigned to receive placebo or fluconazole (400 mg daily). Fluconazole or placebo was administered prophylactically from the start of the conditioning regimen until the neutrophil count returned to 1000 per microliter, toxicity was suspected, or a systemic fungal infection was suspected or proved.

RESULTS

By the end of the treatment period, 67.2 percent of the 177 patients assigned to placebo had a positive fungal culture of specimens from any site, as compared with 29.6 percent of the 179 patients assigned to fluconazole. Among these, superficial infections were diagnosed in 33.3 percent of the patients receiving placebo and in 8.4 percent of the patients receiving fluconazole (P less than 0.001). Systemic fungal infections occurred in 28 patients who received placebo as compared with 5 who received fluconazole (15.8 percent vs. 2.8 percent, P less than 0.001). Fluconazole prevented infection with all strains of candida except Candida krusei. Fluconazole was well tolerated, although patients who received it had a higher mean increase in alanine aminotransferase levels than patients who received placebo. Although there was no significant difference in overall mortality between the groups, fewer deaths were ascribed to acute systemic fungal infections in the group receiving fluconazole than in the group receiving placebo (1 of 179 vs. 10 of 177, P less than 0.001).

CONCLUSIONS

Prophylactic administration of fluconazole to recipients of bone marrow transplants reduces the incidence of both systemic and superficial fungal infections.

Catalase-negative listeria monocytogenes causing meningitis in an adult. Clinical and laboratory features

A 63-year-old previously healthy woman presented with acute meningitis. Cultures of the cerebrospinal fluid yielded a serotype 1/2a isolate of Listeria monocytogenes that was biochemically typical in all respects, other than the reproducible lack of catalase production. During therapy, the patient developed oculomotor dysfunction that was attributed to an abscess in the internal capsule. This case report documents the existence of catalase-negative L. monocytogenes indicating that catalase production should not be a strict criterion for identification of Listeria. Furthermore, this clinical experience extends in vitro and experimental animal studies indicating that catalase production is not a necessary virulence factor for invasion by Listeria.

Gastrointestinal candidiasis in a murine model of severe combined immunodeficiency syndrome

A murine model of severe combined immunodeficiency syndrome (scid mice) affords an opportunity to study the interaction of Candida albicans with a host lacking functional B- and T-cell mechanisms. We have previously reported no significant difference in yeast recovery after intravenous challenge of BALB/c mice and scid mice with C. albicans (S. Mahanty, R.A. Greenfield, W.A. Joyce, and P.W. Kincade, Infect. Immun. 56:3162-3166, 1988). In this study, we evaluate the course of gastrointestinal candidiasis after a single oral challenge with C. albicans. BALB/c and scid mice received H2O containing 10(6) C. albicans per ml for 16 h. Half the mice of each strain continuously received H2O containing 1 mg of tetracycline per ml. Stool samples were cultured for yeast twice weekly until they were negative three consecutive times or positive for 8 weeks. Mice were then sacrificed for quantitative cultures of liver, spleen, and kidneys. At eight weeks postinoculation, 2 of 13 BALB/c mice, 0 of 14 BALB/c mice receiving tetracycline, 6 of 12 scid mice, and 8 of 13 scid mice receiving tetracycline had positive stool cultures (P less than 0.05, likelihood ratio chi-square). Quantitative recovery of yeasts from stools was also higher in the scid mice. Cultures of liver, spleen, and kidneys wer negative in all BALB/c mice and essentially all negative in scid mice; a single colony was isolated from the kidney of one scid mouse and the liver of another scid mouse. We conclude that B cells and/or T cells and their products are important in gastrointestinal colonization with C. albicans but that even in their absence, dissemination of infection from the gastrointestinal tract does not consistently occur. Thus, other aspects of host defense must be critical in containing gastrointestinal Candida colonization.

Unusual skin sites of herpes simplex eruptions: delay in diagnosis

Whereas Herpes simplex labialis and genitalis are common and simple to diagnose, herpetic eruptions in other areas are relatively rare and often misdiagnosed. We report five cases of Herpes simplex eruption at unusual sites. Diagnosis was delayed up to 20 years and resulted in unnecessary antibiotic treatment. The recurrent nature of this eruption is the key to diagnosis.

Clinical experience with HIV-infected patients at the University of Oklahoma Health Sciences Center

Two hundred seventy-two patients infected with human immunodeficiency virus (HIV) have received care from the members of the adult infectious disease section at the University of Oklahoma Health Sciences Center. The majority of these patients met the diagnostic criteria for acquired immunodeficiency syndrome. This group of patients was characterized by relatively few parenteral drug abusers, a high incidence of disseminated histoplasmosis, and an unexpectedly low frequency of toxoplasmosis. The prevalence of risk behaviors and endemic disease may be responsible for these particular case distributions.

Inoculation candidiasis in a murine model of severe combined immunodeficiency syndrome

To further elucidate the importance of T- and B-lymphocyte-mediated responses in host defense against systemic infection with Candida albicans, we studied this infection in a murine model of severe combined immunodeficiency (SCID). The course of inoculation candidiasis in these mice, which lack functional T and B lymphocytes, was compared with that in immunologically normal BALB/c mice. Mice were inoculated intravenously with 10(5) yeast cells. Quantitative cultures of liver, spleen, and kidneys were performed with necropsy specimens obtained 1, 3, 7, 10, 14, and 21 days after this intravenous inoculation. The differences in the time courses of recovery of organisms from liver and spleen specimens were not significantly different in the SCID mice compared with the BALB/c mice. The recovery of C. albicans from the kidneys was significantly lower in the SCID mice, indicating less persistence of the organism in the kidneys of the SCID mice than in those of the BALB/c mice. These data indicate that defense mechanisms other than T- and B-lymphocyte-mediated mechanisms are primarily responsible for host defense against inoculation candidiasis.

Analysis of early infectious complications after autologous bone marrow transplantation

We reviewed the hospital course of 35 patients who underwent autologous bone marrow transplantation. Fever and profound neutropenia developed in all. Microbiologically confirmed infection developed in 22 patients, and unconfirmed but clinically evident infection developed in six. A bacterial infection developed in 21 patients (most commonly bacteremia without a detectable focus). Mucocutaneous fungal (12 patients) and viral (13 patients) infections were common, whereas invasive fungal (two patients) and viral (one patient) infections were uncommon. New pulmonary infiltrates developed in seven patients. Six deaths occurred during the initial hospitalization for transplantation, only one of which was directly attributable to infection. Stepwise logistic regression analysis retained male gender, total body irradiation, administration of trimethoprim/sulfamethoxazole, and development of mucositis or diarrhea as predictors of decreased survival, whereas higher pretreatment albumin levels and the administration of oral nonabsorbable antifungals were associated with an increased likelihood of survival. A comparison of these infectious complications with those found in allogeneic bone marrow transplant recipients shows similarities and differences with potentially important implications for patient management.

Comparison of antibody, antigen, and metabolite assays in rat models of systemic and gastrointestinal candidiasis

We compared serial measurements of antibodies to mannan and to a cytoplasmic antigen (enzyme-linked immunosorbent assays), detection of mannan and an unidentified candidal antigen (latex agglutination), and assays of mannose and arabinitol (gas chromatographic assay of per-O-acetylated aldonitrile derivatives). In a high-inoculum intravascular-infection model, antimannan assays were consistently positive beginning on day 2 postinoculation, anti-cytoplasmic antigen assays followed the same time course but were less sensitive, mannan was detected in all samples beginning on day 2 postinoculation, and serum mannose concentrations peaked on day 3 postinoculation and were less sensitive than mannan detection. Other assays were not useful. In a lower-inoculum intravascular-infection model, the antibody assays became positive after a similar interval and remained positive for 28 days, with antimannan again being the more sensitive. Mannan and mannose tests were positive in week 1 postinoculation only, with mannan detection being the more sensitive. In a gastrointestinal-colonization model, antimannan assays become positive after 2 weeks of colonization, whereas anti-cytoplasmic antigen and mannan tests remained negative. In a model of gastrointestinal colonization followed by invasive infection produced by induction of neutropenia, only mannan detection was diagnostically useful. These data, comparing this panel of modern serodiagnostic techniques in controlled models of clinically relevant syndromes of candidiasis, enhance understanding of previous efforts in serodiagnosis of candidiasis and provide a foundation for further prospective studies in patients.

Disruption of myofibrillar energy use: dual mechanisms that may contribute to postischemic dysfunction in stunned myocardium

The abnormalities in regional function produced by myocardial ischemia persist after the ischemic episode resolves. Since a close functional coupling exists between myofibrillar creatine kinase and myosin ATPase, a disruption of this coupling could adversely influence myocardial function and might provide a mechanism for the myocardial dysfunction observed. The purpose of the present study was to determine if an alteration in the activity of creatine kinase associated with the myofibril occurs in the postischemic period. Anesthetized open-chest dogs (n = 6) underwent coronary occlusion for 15 minutes, followed by reperfusion for 15 minutes. In reperfused myocardium, adenine nucleotide content was decreased (72 +/- 10% of nonischemic myocardium, p less than 0.05), documenting the presence of previous ischemia. The creatine phosphate content of reperfused myocardium returned to normal, indicating resumption of myocardial energy production. The creatine kinase activity of purified myofibrils isolated from reperfused myocardium was decreased by 17 +/- 7% compared to that of nonischemic myofibrils (p less than 0.03). In addition, the free adenosine diphosphate concentration in reperfused myocardium was calculated to be 96 microM and was less than the Km of adenosine diphosphate determined for myofibrillar creatine kinase (105 microM). The results suggest two putative mechanisms for disruption of energy use in postischemic myocardium: decreased creatine kinase activity associated with the myofibril, and limitation of substrate necessary for maximal creatine kinase activity.

Serial enzyme-linked immunosorbent assays for antibody to Candida antigens during induction chemotherapy for acute leukemia

Two or more sera were collected from 68 adult patients who received a total of 100 courses of induction chemotherapy for acute leukemia. Sera were tested by ELISAs for antibody to candidal mannan and a major cytoplasmic antigen. Twenty episodes of induction chemotherapy were accompanied by invasive candidiasis of skin, esophagus, or deeper organs. Levels of antibody to mannan rose more than 2.75 times normal activity in nine of these episodes and were already above this level in all sera in two episodes. Levels of antibody to mannan exceeded 2.75 times normal in only two of the remaining episodes in which invasive candidiasis was not observed. An eightfold increase in antibody to mannan occurred at some point in five of the 20 episodes complicated by invasive candidiasis but in only one of the remaining 80 episodes. Antibody to the major cytoplasmic antigen was detected infrequently in sera from episodes complicated by invasive candidiasis. Further studies of precise serial measurements of antibody to mannan therefore appear warranted.

Quantitation of antibody to Candida mannan by enzyme-linked immunosorbent assay

Early clinical diagnosis of invasive candidiasis is difficult. To facilitate rapid diagnosis of Candida infections, we developed an ELISA to quantitate levels of antibody to Candida mannan. The test was standardized by analysis of a nonselected inpatient population to determine a cutoff point defining the upper 5% of such a population as test-positive. Passively acquired sera from patients in intensive care units, patients with neoplastic disease or recent renal allografts, and other patients were analyzed. There was no significant difference between the number of positive tests obtained from patients in whom candidiasis was considered but cultures were negative and from the nonselected inpatient population. Positive tests were obtained from 18.5% of patients with Candida mucocutaneous colonization or infection and 40% and 63.6% of patients with probable and proven invasive candidiasis, respectively. Patients with neoplastic disease had lower test sensitivity than patients in other test categories. These results demonstrate the usefulness of a simple, rapid, standardized test for quantitation of levels of antibody activity to Candida mannan in the serodiagnosis of candidiasis.

Torulopsis glabrata pneumonia: value of serologic testing

An immunocompromised patient with severe hypoxemia was found by transbronchial lung biopsy to have Torulopsis glabrata as the sole pathogen in lung. An antibody response to this organism was demonstrated, confirming its role as a pathogen and indicating a role for serodiagnosis of T glabrata infection.