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.