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1.
Allergy Asthma Proc ; 44(2): 130-135, 2023 03 01.
Article in English | MEDLINE | ID: mdl-36872442

ABSTRACT

Background: Pneumonia is the most common reason for pediatric hospitalizations. The impact of penicillin allergy labels among children with pneumonia has not been well studied. Objective: This study assessed the prevalence and impact of penicillin allergy labels among children admitted with pneumonia over a 3-year period at a large academic children's center. Methods: Inpatient charts of pneumonia admissions with a documented allergy to a type of penicillin from January to March in 2017, 2018, and 2019 were reviewed and compared with pneumonia admissions without the label over the same time with regard to days of antimicrobial treatment, route of antimicrobial therapy, and days of hospitalization. Results: There were 470 admissions for pneumonia during this time period, of which 48 patients (10.2%) carried a penicillin allergy label. Hives and/or swelling comprised 20.8% of the allergy labels. Other labels included nonpruritic rashes, gastrointestinal GI symptoms, unknown/undocumented reactions, or other reasons. There were no significant differences between those with a penicillin allergy label to those without regarding days of antimicrobial treatment (inpatient and outpatient), route of antimicrobial therapy, and days of hospitalization. Those with a penicillin allergy label were less likely to be prescribed a penicillin product (p < 0.002). Of the 48 patients who were allergy labeled, 23% (11/48) were given a penicillin medication without adverse reaction. Conclusion: Ten percent of pediatric admissions for pneumonia had a label of penicillin allergy, similar to the overall population. The hospital course and clinical outcome were not significantly affected by the penicillin allergy label. The majority of documented reactions were of low risk for immediate allergic reactions.


Subject(s)
Hypersensitivity, Immediate , Pneumonia , Urticaria , Humans , Child , Hospitalization , Penicillins
2.
J Neurosurg Case Lessons ; 5(4)2023 Jan 23.
Article in English | MEDLINE | ID: mdl-36692066

ABSTRACT

BACKGROUND: Multiple bilateral brain abscesses occur rarely in immunocompetent patients. Hematogenous spread to the central nervous system (CNS) allows suppuration and abscess formation in the privileged immune environment of the CNS; hematogenous spread to the spinal cord is extremely rare and the combination of multifocal brain abscesses and intramedullary abscesses has not been reported. This report presents a rare presentation and diagrams a treatment algorithm involving iterative minimal access surgeries and prolonged medical management. OBSERVATIONS: The authors present a case of an 18-year-old male with numerous multifocal and bilateral intraparenchymal abscesses and a medically resistant C5 intramedullary spinal cord abscess. The symptomatic patient had a left oculomotor palsy and left hemiparesis, ultimately undergoing ultrasound-guided aspiration of abscesses in the left frontal and left cerebral peduncle. Following transient motor improvement, he evolved tetraparesis prompting spinal cord imaging and emergent ultrasound-guided needle aspiration of an occult C5 intramedullary spinal cord abscess. The patient received appropriate medical therapy, completed inpatient rehabilitation, and made a full recovery. LESSONS: Needle- and ultrasound-guided catheter drainage of CNS abscesses should be considered for symptomatic lesions. Following the neurological examination closely is extremely important; if the expected neurological improvement is delayed or regresses, then expanded imaging is warranted.

3.
Childs Nerv Syst ; 38(3): 669-672, 2022 03.
Article in English | MEDLINE | ID: mdl-34097098

ABSTRACT

Depressed skull fractures from dog bites are common pediatric head injuries which are contaminated with native skin and canine oral flora. Outcomes can potentially be catastrophic. Thus, these injuries require proper initial management to prevent future complications. We present an 18-month-old female who was bitten by a Great Dane dog and resulted in a small left temporal depressed skull fracture with an underlying brain contusion. This was initially treated conservatively with antibiotics and bedside irrigation. Five weeks later, she developed a large multiloculated abscess with mass effect, which required surgical aspiration and wound debridement. After long-term antibiotics, she made a full neurologic recovery. Our case illustrates the importance of washing out a seemingly inconsequential depressed skull fracture from a dog bite to avoid development of a cerebral abscess.


Subject(s)
Bites and Stings , Craniocerebral Trauma , Skull Fracture, Depressed , Skull Fractures , Animals , Bites and Stings/complications , Child , Craniocerebral Trauma/surgery , Debridement , Dogs , Female , Humans , Skull Fracture, Depressed/diagnostic imaging , Skull Fractures/complications , Skull Fractures/diagnostic imaging
4.
Surg Neurol Int ; 12: 325, 2021.
Article in English | MEDLINE | ID: mdl-34345466

ABSTRACT

BACKGROUND: Intraparenchymal brain abscess is a collection of microbes caused by inoculation through direct extension or hematogenous spread. Although rare, intraparenchymal abscesses are potentially fatal and can be detected when patients are symptomatic due to local mass effect on adjacent neural tissue. Brain abscess treatment includes medical management with appropriate antibiotics alone or medical management in combination with surgical debridement. Treatment strategies depend on the size and location of disease, as well as the virulence of the microorganism. Similar to medical management strategies, surgical strategies among providers are not uniform, with variation in approaches from complete extirpation of the abscess, including the abscess wall, to minimally invasive stereotactic needle aspiration. In particular, for children, there are no guidelines for therapy. CASE DESCRIPTION: We report a case of giant Actinomycosis right frontal brain abscess in an immunocompetent child without risk factors. A review of the literature for the treatment of brain abscess caused very rarely by Actinomyces in children is performed. CONCLUSION: Successful treatment of brain access depends on organism and location. The even more uncommon giant intraparenchymal abscesses can be managed with minimal access and prolonged antibiosis, especially when slow-growing organisms are identified. Long-term follow-up should be employed to mitigate missed late failures.

6.
Perit Dial Int ; 40(1): 96-99, 2020 01.
Article in English | MEDLINE | ID: mdl-32063142

ABSTRACT

Fungal peritonitis in the peritoneal dialysis population is difficult to diagnose promptly due to the inherently slow cultivation-based methods currently required for identification of peritonitis pathogens. Because of the moderate risk for severe complications, the need for rapid diagnostics is considerable. One possible solution to this unmet need is the T2Candida Panel, a new technology designed to detect the most common pathogenic Candida spp. directly from whole blood specimens in as little as a few hours. We hypothesized that this technology could be applied to the detection of Candida in peritoneal dialysate, a matrix not currently approved by the Food and Drug Administration for testing by this system. Remnant dialysate samples from three healthy (noninfected) pediatric peritoneal dialysis patients were spiked with Candida glabrata, serially diluted, and tested in triplicate with unaltered dialysate specimens. The assay detected C. glabrata in 100% of spiked dialysate samples across the full spectrum of dilutions tested, and no assay inhibition or cross-reactivity was noted. These findings suggest one of possibly more applications of this technology. The positive clinical implications of this test will continue to be realized as its use is validated in peritoneal dialysate and other patient specimen types.


Subject(s)
Candida glabrata/isolation & purification , Candidiasis/diagnosis , Dialysis Solutions/analysis , Peritoneal Dialysis/adverse effects , Peritonitis/diagnosis , Peritonitis/microbiology , Humans , Kidney Failure, Chronic/therapy , Sensitivity and Specificity
7.
JAMA Netw Open ; 3(1): e1918565, 2020 01 03.
Article in English | MEDLINE | ID: mdl-31899532

ABSTRACT

Importance: Timely initiation of intravenous immunoglobulin plus aspirin is necessary for decreasing the risk of recrudescent fever and coronary artery abnormalities in children with Kawasaki disease (KD). The optimal dose of aspirin, however, remains unclear. Objective: To evaluate whether initial treatment with low-dose compared with high-dose aspirin in children with KD is associated with an increase in fever recrudescence. Design, Setting, and Participants: A retrospective cohort study of 260 children with KD at Riley Hospital for Children, Indianapolis, Indiana, between January 1, 2007, and December 31, 2018, was conducted. Children aged 0 to 18 years with a first episode of KD, identified by International Classification of Diseases, Ninth Revision and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision diagnosis codes treated within 10 days of symptom onset with high-dose intravenous immunoglobulin plus aspirin were eligible. Patients who received an alternative diagnosis, experienced a second episode of KD, did not receive intravenous immunoglobulin plus aspirin for initial treatment, were not treated within 10 days of symptoms, or had incomplete records were excluded. Exposures: High-dose (≥10 mg/kg/d) or low-dose (<10 mg/kg/d) aspirin therapy. Main Outcomes and Measures: The primary outcome was recrudescent fever necessitating retreatment of KD. The secondary outcomes were coronary artery abnormalities and hospital length of stay. Results: Among the 260 patients included, the median (interquartile range) age was 2.5 (1.6-4.3) years, 103 (39.6%) were girls, 166 (63.8%) were non-Hispanic white, 57 (21.9%) were African American, 22 (8.5%) were Asian, 11 (4.2%) were Hispanic, and 4 (1.5%) were of unknown race/ethnicity. One hundred-forty-two patients (54.6%) were treated with low-dose aspirin. There was no association between recrudescent fever and aspirin dose, with 39 children (27.5%) having recrudescent fever in the low-dose group compared with 26 children (22.0%) in the high-dose group (odds ratio [OR], 1.34; 95% CI, 0.76-2.37; P = .31), with similar results after adjusting for potential confounding variables (OR, 1.63; 95% CI, 0.89-2.97; P = .11). In a subset analysis of 167 children with complete KD, however, there was nearly a 2-fold difference in the odds of recrudescent fever with low-dose aspirin (OR, 1.87; 95% CI, 0.82-4.23; P = .14), although this difference did not reach statistical significance. In addition, no association was identified between treatment group and coronary artery abnormalities (low-dose, 7.4% vs high-dose, 9.4%; OR, 0.86; 95% CI, 0.48-1.55; P = .62) or median (interquartile range) length of stay (3 [3-5] days for both groups; P = .27). Conclusions and Relevance: In this study, low-dose aspirin for the initial treatment of children with KD was not associated with fever recrudescence or coronary artery abnormalities. Given the potential benefits, further study of low-dose aspirin to detect potentially clinically relevant outcome differences is warranted to inform treatment decisions and guideline development.


Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/administration & dosage , Aspirin/administration & dosage , Fever/prevention & control , Immunoglobulins, Intravenous/administration & dosage , Mucocutaneous Lymph Node Syndrome/drug therapy , Adolescent , Child , Child, Preschool , Coronary Artery Disease/epidemiology , Coronary Artery Disease/etiology , Coronary Artery Disease/prevention & control , Dose-Response Relationship, Drug , Drug Therapy, Combination , Female , Fever/epidemiology , Fever/etiology , Humans , Infant , Infant, Newborn , Male , Mucocutaneous Lymph Node Syndrome/complications , Recurrence , Retrospective Studies , Risk Factors , Treatment Outcome
8.
Diagn Microbiol Infect Dis ; 95(3): 114841, 2019 Nov.
Article in English | MEDLINE | ID: mdl-31422873

ABSTRACT

OBJECTIVES: To compare the performance and time-to-result (TTR) for antimicrobial susceptibility testing (AST) of positive blood cultures (PBC) using the Accelerate Pheno™ system (AXDX) and both a direct VITEK® 2 card inoculation workflow (DV2) and traditional FDA-approved VITEK® 2 workflow using subcultured isolates (V2). METHODS: Patient samples with monomicrobial Gram-negative rod bacteremia were tested on AXDX and DV2 in tandem and compared to V2 AST results. Categorical agreement (CA) errors were adjudicated using broth microdilution. Instrumentation times and AST TTR were compared. RESULTS: AXDX and DV2 had a CA of 93.4% and 97.4%, respectively, compared to V2. Postadjudication, AXDX, DV2, and V2 had CA of 94.7%, 95.7%, and 96.5%, respectively. Instrument run times were 6.6 h, 9.4 h, and 9.2 h, and AST TTR were 8.9 h, 12.9 h and 35.5 h, respectively. CONCLUSIONS: AXDX and DV2 ASTs are fast and reliable, which may have significant antimicrobial stewardship implications.


Subject(s)
Blood Culture , Diagnostic Tests, Routine/methods , Microbial Sensitivity Tests/methods , Antimicrobial Stewardship , Bacteremia/microbiology , Diagnostic Tests, Routine/instrumentation , Diagnostic Tests, Routine/standards , Gram-Negative Bacteria/isolation & purification , Gram-Negative Bacteria/metabolism , Gram-Negative Bacterial Infections/microbiology , Humans , Microbial Sensitivity Tests/instrumentation , Microbial Sensitivity Tests/standards , Prospective Studies , Time Factors , Workflow , beta-Lactamases/biosynthesis
9.
Contemp Clin Trials ; 79: 98-103, 2019 04.
Article in English | MEDLINE | ID: mdl-30840903

ABSTRACT

BACKGROUND: Although intravenous immunoglobulin (IVIG) is effective therapy for Kawasaki disease (KD), the most common cause of acquired heart disease in children, 10-20% of patients are IVIG-resistant and require additional therapy. This group has an increased risk of coronary artery aneurysms (CAA) and there has been no adequately powered, randomized clinical trial in a multi-ethnic population to determine the optimal therapy for IVIG-resistant patients. OBJECTIVES: The primary outcome is duration of fever in IVIG-resistant patients randomized to treatment with either infliximab or a second IVIG infusion. Secondary outcomes include comparison of inflammatory markers, duration of hospitalization, and coronary artery outcome. An exploratory aim records parent-reported outcomes including signs, symptoms and treatment experience. METHODS: The KIDCARE trial is a 30-site randomized Phase III comparative effectiveness trial in KD patients with fever ≥36 h after the completion of their first IVIG treatment. Eligible patients will be randomized to receive either a second dose of IVIG (2 g/kg) or infliximab (10 mg/kg). Subjects with persistent or recrudescent fever at 24 h following completion of the first study treatment will cross-over to the other treatment arm. Subjects will exit the study after their first outpatient visit (5-18 days following last study treatment). The parent-reported outcomes, collected daily during hospitalization and at home, will be compared by study arm. CONCLUSION: This trial will contribute to the management of IVIG-resistant patients by establishing the relative efficacy of a second dose of IVIG compared to infliximab and will provide data regarding the patient/parent experience of these treatments.


Subject(s)
Fever/drug therapy , Immunoglobulins, Intravenous/therapeutic use , Infliximab/therapeutic use , Mucocutaneous Lymph Node Syndrome/drug therapy , Adolescent , Child , Child, Preschool , Comparative Effectiveness Research , Cross-Over Studies , Drug Resistance , Echocardiography , Female , Fever/etiology , Humans , Immunoglobulins, Intravenous/administration & dosage , Immunoglobulins, Intravenous/adverse effects , Infant , Inflammation Mediators/analysis , Infliximab/administration & dosage , Infliximab/adverse effects , Length of Stay , Male , Mucocutaneous Lymph Node Syndrome/complications
10.
J Antimicrob Chemother ; 74(Suppl 1): i16-i23, 2019 01 01.
Article in English | MEDLINE | ID: mdl-30690542

ABSTRACT

Objectives: We evaluated the performance and time to result for pathogen identification (ID) and antimicrobial susceptibility testing (AST) of the Accelerate Pheno™ system (AXDX) compared with standard of care (SOC) methods. We also assessed the hypothetical improvement in antibiotic utilization if AXDX had been implemented. Methods: Clinical samples from patients with monomicrobial Gram-negative bacteraemia were tested and compared between AXDX and the SOC methods of the VERIGENE® and Bruker MALDI Biotyper® systems for ID and the VITEK® 2 system for AST. Additionally, charts were reviewed to calculate theoretical times to antibiotic de-escalation, escalation and active and optimal therapy. Results: ID mean time was 21 h for MALDI-TOF MS, 4.4 h for VERIGENE® and 3.7 h for AXDX. AST mean time was 35 h for VITEK® 2 and 9.0 h for AXDX. For ID, positive percentage agreement was 95.9% and negative percentage agreement was 99.9%. For AST, essential agreement was 94.5% and categorical agreement was 93.5%. If AXDX results had been available to inform patient care, 25% of patients could have been put on active therapy sooner, while 78% of patients who had therapy optimized during hospitalization could have had therapy optimized sooner. Additionally, AXDX could have reduced time to de-escalation (16 versus 31 h) and escalation (19 versus 31 h) compared with SOC. Conclusions: By providing fast and reliable ID and AST results, AXDX has the potential to improve antimicrobial utilization and enhance antimicrobial stewardship.


Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteremia/microbiology , Gram-Negative Bacteria/drug effects , Gram-Negative Bacteria/isolation & purification , Gram-Negative Bacterial Infections/microbiology , Microbial Sensitivity Tests/methods , Adolescent , Adult , Aged , Aged, 80 and over , Anti-Bacterial Agents/therapeutic use , Antimicrobial Stewardship , Blood Culture/methods , Blood Culture/standards , Child , Child, Preschool , Clinical Laboratory Techniques/methods , Clinical Laboratory Techniques/standards , Female , Gram-Negative Bacterial Infections/diagnosis , Gram-Negative Bacterial Infections/drug therapy , Humans , In Situ Hybridization, Fluorescence/methods , In Situ Hybridization, Fluorescence/standards , Infant , Male , Microbial Sensitivity Tests/standards , Middle Aged , Phenotype , Prospective Studies , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/standards , Young Adult
11.
JMM Case Rep ; 4(5): e005091, 2017 May.
Article in English | MEDLINE | ID: mdl-29026619

ABSTRACT

Introduction. It can be difficult to catalogue the individual organisms comprising polymicrobial patient infections, both because conventional clinical microbiological culture does not facilitate the isolation and enumeration of all members of a complex microbial community, and because fastidious organisms may be mixed with organisms that grow rapidly in vitro. Empiric antimicrobial treatment is frequently employed based on the anatomical site and the suspected source of the infection, especially when an appropriately collected surgical specimen is not obtained. Case presentation. We present a case of an intra-abdominal infection in a patient with complex anatomy and recurrent urinary tract infections. Imaging did not reveal a clear source of infection, no growth was obtained from urine cultures and initial abdominal fluid cultures were also negative. In contrast, 16S rRNA deep sequencing of abdominal fluid samples revealed mixed bacterial populations with abundant anaerobes, including Actinotignum schaalii (Actinobaculum schaalii). Ultimately, only Enterobacter cloacae complex and meticillin-resistant Staphylococcus aureus, both of which were identified by sequencing, were recovered by culture. Conclusion. The clinical application of 16S rRNA deep sequencing can more comprehensively and accurately define the organisms present in an individual patient's polymicrobial infection than conventional microbiological culture, detecting species that are not recovered under standard culture conditions or that are otherwise unexpected. These results can facilitate effective antimicrobial stewardship and help elucidate the possible origins of infections.

13.
Open Forum Infect Dis ; 3(3): ofw160, 2016 Sep.
Article in English | MEDLINE | ID: mdl-27704015

ABSTRACT

Background. Pediatric Kawasaki disease (KD) and human immunodeficiency virus (HIV)+ adult Kawasaki-like syndrome (KLS) are dramatic vasculitides with similar physical findings. Both syndromes include unusual arterial histopathology with immunoglobulin (Ig)A+ plasma cells, and both impressively respond to pooled Ig therapy. Their distinctive presentations, histopathology, and therapeutic response suggest a common etiology. Because blood is in immediate contact with inflamed arteries, we investigated whether KD and KLS share an inflammatory signature in serum. Methods. A custom multiplex enzyme-linked immunosorbent assay (ELISA) defined the serum cytokine milieu in 2 adults with KLS during acute and convalescent phases, with asymptomatic HIV+ subjects not taking antiretroviral therapy serving as controls. We then prospectively collected serum and plasma samples from children hospitalized with KD, unrelated febrile illnesses, and noninfectious conditions, analyzing them with a custom multiplex ELISA based on the KLS data. Results. Patients with KLS and KD subjects shared an inflammatory signature including acute-phase reactants reflecting tumor necrosis factor (TNF)-α biologic activity (soluble TNF receptor I/II) and endothelial/smooth muscle chemokines Ccl1 (Th2), Ccl2 (vascular inflammation), and Cxcl11 (plasma cell recruitment). Ccl1 was specifically elevated in KD versus febrile controls, suggesting a unique relationship between Ccl1 and KD/KLS pathogenesis. Conclusions. This study defines a KD/KLS inflammatory signature mirroring a dysfunctional response likely to a common etiologic agent. The KD/KLS inflammatory signature based on elevated acute-phase reactants and specific endothelial/smooth muscle chemokines was able to identify KD subjects versus febrile controls, and it may serve as a practicable diagnostic test for KD.

15.
JPEN J Parenter Enteral Nutr ; 40(8): 1194-1196, 2016 11.
Article in English | MEDLINE | ID: mdl-26150410

ABSTRACT

Malassezia species (formerly known as Pityrosporum) are part of normal human skin flora and have been associated with benign dermatologic conditions, such as seborrheic dermatitis and tinea versicolor. In rare cases, however, Malassezia has been associated with systemic disease in immunocompromised patients and infants in the neonatal intensive care unit. Malassezia species require long-chain fatty acids for growth and therefore have a known predilection for individuals receiving lipid containing intravenous parenteral nutrition (PN). Systemic infections are characterized by prolonged fevers and illness but can include nonspecific signs and symptoms. We present the diagnosis and management of a rare case of an immunocompetent, nonneonatal, PN-dependent child with Malassezia furfur pneumonia.


Subject(s)
Malassezia/isolation & purification , Parenteral Nutrition/adverse effects , Pneumonia/diagnosis , Pneumonia/microbiology , Child , Fat Emulsions, Intravenous/adverse effects , Fat Emulsions, Intravenous/chemistry , Female , Host-Pathogen Interactions , Humans , Immunocompromised Host , Intensive Care Units, Neonatal , Skin/microbiology , Williams Syndrome/microbiology , Williams Syndrome/therapy
16.
J Pharm Pract ; 28(4): 430-3, 2015 Aug.
Article in English | MEDLINE | ID: mdl-26033796

ABSTRACT

A 13-year-old female experienced a recurrence of baclofen pump-related central nervous system (CNS) infection caused by Achromobacter, despite absence of retained foreign material. Due to the failure of meropenem (120 mg/kg/d in divided doses every 8 hours and infused over 30 minutes) in the initial infection, the dose was infused over 4 hours during the recurrence. Meropenem is an antibiotic for which efficacy is time dependent, and 4-hour versus 30-minute infusions have been shown to prolong the time the concentration of the antibiotic exceeds the minimum inhibitory concentration (MIC) of the organism at the site of infection (T>MIC). Meropenem serum concentrations were obtained and indicated that T>MIC was at least 75% of the dosing interval. Our patient improved with no noted recurrences or adverse effects on the extended-infusion meropenem regimen. Utilization of extended-infusion beta-lactam dosing whenever possible in the treatment of serious infections caused by gram-negative organisms should be considered, as this dosing appears to be safe and improves the probability of achieving pharmacokinetic/pharmacodynamic goals.


Subject(s)
Achromobacter denitrificans/isolation & purification , Baclofen/administration & dosage , Meningitis, Bacterial/drug therapy , Thienamycins/administration & dosage , Adolescent , Anti-Bacterial Agents/administration & dosage , Anti-Bacterial Agents/therapeutic use , Drug Administration Schedule , Female , Gram-Negative Bacterial Infections/drug therapy , Gram-Negative Bacterial Infections/etiology , Gram-Negative Bacterial Infections/microbiology , Humans , Infusion Pumps, Implantable/adverse effects , Injections, Spinal , Meningitis, Bacterial/etiology , Meningitis, Bacterial/microbiology , Meropenem , Microbial Sensitivity Tests , Muscle Relaxants, Central/administration & dosage , Recurrence , Thienamycins/therapeutic use
18.
Pediatr Clin North Am ; 60(2): 507-27, 2013 Apr.
Article in English | MEDLINE | ID: mdl-23481114

ABSTRACT

Malaria, diarrhea, respiratory infections, and cutaneous larva migrans are common travel-related infections observed in children and adolescents returning from trips to developing countries. Children visiting friends and relatives are at the highest risk because few visit travel clinics before travel, their stays are longer, and the sites they visit are more rural. Clinicians must be able to prepare their pediatric-age travelers before departure with preventive education, prophylactic and self-treating medications, and vaccinations. Familiarity with the clinical manifestations and treatment of travel-related infections will secure prompt and effective therapy.


Subject(s)
Anti-Infective Agents/therapeutic use , Fever/etiology , Infections , Travel , Adolescent , Anti-Infective Agents/administration & dosage , Child , Child, Preschool , Diarrhea/etiology , Diarrhea/prevention & control , Eosinophilia/etiology , Humans , Infections/diagnosis , Infections/epidemiology , Infections/etiology , Infections/microbiology , Infections/parasitology , Infections/therapy , Infections/virology , Jaundice/etiology , Malaria/etiology , Malaria/prevention & control , Skin Diseases, Infectious/etiology , Skin Diseases, Infectious/prevention & control
19.
Arthritis Rheum ; 46(7): 1905-13, 2002 Jul.
Article in English | MEDLINE | ID: mdl-12124875

ABSTRACT

OBJECTIVE: To determine whether serum amyloid A (SAA) is internalized by and processed in macrophages en route to deposition as extracellular amyloid. METHODS: SAA was tracked in cultures of peritoneal macrophages, using a pulse-chase protocol. Macrophages were pulsed with either fluorescently (with Texas Red) tagged SAA (TxR-SAA) or iodinated SAA ((125)I-SAA). Cells were then rinsed and shifted to chase medium containing unlabeled SAA and amyloid-enhancing factor (AEF) to induce amyloid formation. At selected times, TxR-SAA in living cells was observed by confocal scanning microscopy. (125)I-SAA was visualized and quantified in cell lysates and medium by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and phosphorimaging. The presence of amyloid was confirmed by Congo red staining. RESULTS: Confocal microscopy immediately after the pulse revealed TxR-SAA in endosomal vesicles, with no extracellular or cell surface accumulation. After 24 hours and 72 hours of chase, virtually all TxR-SAA remained intracellular. By 10 days, extracellular fluorescence was very strong, indicating that SAA had moved out of cells. Congo red staining revealed amyloid colocalized with areas of extracellular fluorescence. Experiments using (125)I-SAA showed that while 90-95% of internalized (125)I-SAA was degraded within 24 hours, 5-10% persisted as intact SAA or SAA peptides. Immediately after the pulse, SAA was full-length, but within 24 hours, discrete (125)I-SAA peptides were seen. Each peptide had an intact SAA amino-terminus, as expected for AA protein. Amyloid was detected in cultures as early as 24 hours after initiation of treatment with SAA and AEF and appeared to be intracellular. CONCLUSION: The results of this study provide direct evidence that SAA internalized by and processed in macrophages forms extracellular amyloid. Based on the presence of (125)I-AA protein in macrophage lysates prior to the appearance of extracellular TxR-labeled amyloid, it was concluded that cleavage of SAA to AA occurs intracellularly.


Subject(s)
Apolipoproteins/metabolism , Endocytosis/physiology , Extracellular Space/metabolism , Macrophages, Peritoneal/physiology , Serum Amyloid A Protein/metabolism , Animals , Congo Red , Electrophoresis, Polyacrylamide Gel , Fluorescence , In Vitro Techniques , Iodine Radioisotopes , Macrophages, Peritoneal/metabolism , Mice , Microscopy, Confocal
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