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Biomedical subjects

J N Longfield

Publications and source records attributed to J N Longfield.

11 recordsLinked to original sources
PubMed1995

Epidemic streptococcal disease among Army trainees, July 1989 through June 1991.

Outbreaks of group A streptococcal infection occurred at four of seven US Army basic training installations between 1 July 1989 and 30 June 1991. Study data were collected through a respiratory disease surveillance program and on-site epidemiologic investigations. Although hospitalizations were frequent (range, 191-334) during each outbreak, average rates of hospitalization were low (2.4-4.8 hospitalizations/1000 trainees/week). Outbreak-associated morbidity included streptococcal toxic shock syndrome (2 cases, 1 fatal), acute rheumatic fever (6), acute glomerulonephritis (1), scarlet fever (1), and numerous other invasive sequelae. Four serotypes of Streptococcus pyogenes (M-1, -3, -5, and -18) were identified; M-18 caused significant disease at 2 installations. Disease control was rapidly achieved through prophylaxis programs using benzathine penicillin G in nonallergic trainees. These outbreaks extend other reports that document an evolution of the nature and severity of circulating S. pyogenes in the United States.

Disease Outbreaks↗
PubMed1994

Transfusion-associated human immunodeficiency virus type 1 from screened antibody-negative blood donors.

Cases of human immunodeficiency virus type 1 (HIV-1) infection acquired from transfusion of screened antibody-negative blood have been reported since 1986. Recent reports have proposed new combination antibody assays or the addition of HIV-1 p24 antigen testing to enhance the screening of blood donations further. Since antibody testing for HIV-1 began in 1985, 700,000 donor units have been screened at US Army blood donor centers. The US Army blood donor/recipient "lookback" program recently identified two cases of HIV-1 infection that resulted from a screened negative donation. Samples from the implicated unit, as well as from previous donations from the same donor, were available for testing to assess the performance of current screening methods. Sequential donation samples were assayed by five different Food and Drug Administration-approved HIV-1 screening enzyme-linked immunosorbent assays, a Food and Drug Administration-approved Western blot, a recombinant envelope-based enzyme-linked immunosorbent assay, a p24 antigen capture assay, a radioimmunoprecipitation assay, and a polymerase chain reaction. The HIV-1 p24 antigen and genomic RNA material were detected in a donation that was screened as negative by four of the five Food and Drug Administration-licensed screening enzyme-linked immunosorbent assays. Two recipients of transfusion products from this donation became infected with HIV-1. A sample from a prior donation from this donor was negative for HIV-1 by all assays. The status of blood donors who are in the early stages of HIV-1 infection may not be detected by current screening methods. While this is a rare phenomenon, it highlights the need for technologic developments in screening methods to narrow the time between infection and detection. In addition, it emphasizes the need for more effective education and counseling to enhance the utility of self=deferral.

Adult↗
PubMed1990

Varicella outbreaks in Army recruits from Puerto Rico. Varicella susceptibility in a population from the tropics.

Two outbreaks of varicella consisting of a total of 105 cases occurred in a highly varicella-susceptible population of young adult Army recruits from Puerto Rico enrolled in the Defense Language Institute in San Antonio, Tex, between October 1986 and November 1987. Epidemiologic investigation found a significantly higher risk for enlisted recruits housed in open barracks than for officers housed in private rooms. The attack rate in the first outbreak was 30%, with an estimated attack rate of 71% among susceptible persons. Serologic testing of 810 adult recruits from Puerto Rico for varicella-zoster antibody by means of an enzyme-linked immunosorbent assay procedure found 42% to be seronegative, with no significant difference by sex. The enzyme-linked immunosorbent assay test had a positive predictive value for absence of disease development of 95% in the second outbreak. Serologic test results were successfully used as part of the outbreak control strategy, with a resultant decrease in attack rates to 19% overall and 30% among susceptible persons in the second outbreak. Uniquely susceptible adult populations placed in conditions with high likelihood of infection on exposure are potential candidates for the varicella vaccine after its licensure.

Adult↗
PubMed1985

Multiple-dose vials: persistence of bacterial contaminants and infection control implications.

Due to sporadic infections attributed to contaminated multiple-dose medication vials (MDV), some authorities have suggested discarding all MDV within 24 hours. We inoculated 11 commonly used medications with suspensions of 10 bacterial species previously associated with contaminated parenteral solutions and determined microbial persistence at both room and refrigerator temperature. At 22 degrees C, atropine, curare, folic acid, NPH insulin and triamcinolone did not allow microbial persistence beyond 4 hours. Lidocaine and heparin were sterile by 24 hours. Regular insulin, immune serum globulin, and myochrysine allowed persistence for up to 7 days. At 4 degrees C, bacterial persistence was significantly prolonged for all medications including those MDV requiring refrigeration. No organisms proliferated; however, F. meningosepticum and P. maltophilia were particularly persistent at both temperatures. The risk of persistent MDV contamination appears to be dependent upon specific pharmaceutical, microbe and storage temperature interactions. Recommendations for the refrigeration of MDV medications may require reevaluation on a product-by-product basis.

Bacteria↗
PubMed1985

Methicillin-resistant Staphylococcus aureus (MRSA): risk and outcome of colonized vs. infected patients.

A retrospective study of 204 patients culture positive for methicillin-resistant Staphylococcus aureus compared infected and colonized patients. Seventy-eight patients were colonized and never developed infection (C), 24 were colonized and subsequently infected (C----I), and 102 patients had 1 or more nosocomial infections with MRSA at time of first culture (I). The most prevalent sites of infection were wound (26.5%) and blood-stream (20.7%), whereas the respiratory tract and surgical wounds were both frequent sites of colonization. Stepwise discriminant analysis found the most important factors in differentiating likelihood of colonization vs. infection were recent prior hospitalization, history of wound debridement, and number of invasive procedures. Ten percent of (C) died and 25.5% of (I) died. MRSA contributed to death in 57.6% of the (I) deaths (p less than .05). These results underscore the importance of differentiating (C) vs. (I) in hospitals where MRSA is endemic so that early specific treatment may be initiated. Risk factors for infection should be discriminated from those for acquisition of the organism.

Cross Infection↗
PubMed1985

Comparison of single-dose tetracycline hydrochloride to conventional therapy of urinary tract infections.

Sixty-two women with signs and symptoms compatible with lower urinary tract infections were randomized to receive single-dose tetracycline (2 g), multi-dose tetracycline (500 mg four times per day for 10 days), or single-dose amoxicillin (3 g). Urine cultures were obtained upon entry into the study and on days 4, 14, and 28 after therapy. Single-dose tetracycline cured 12 of 16 (75%) of women with documented urinary tract infections, compared with 15 of 16 (94%) in the multi-dose tetracycline group and 7 of 13 (54%) receiving single-dose amoxicillin. Mild nausea in 3 of 20 patients (15%) was the only complication in the single-dose tetracycline group. Two grams of single-dose tetracycline is as effective as other reported regimens regardless of the susceptibility of the initial pathogen and has minimal toxicity.

Adolescent↗
PubMed1982

Teaching concepts of clinical measurement variation to medical students.

An exercise in clinical epidemiology was developed for medical students to demonstrate the process and limitations of scientific measurement using models that simulate common clinical experiences. All scales of measurement (nominal, ordinal and interval) were used to illustrate concepts of intra- and interobserver variation, systematic error, recording error, and procedural error. In a laboratory, students a) determined blood pressures on six videotaped subjects, b) graded sugar content of unknown solutions from 0 to 4+ using Clinitest tablets, c) measured papules that simulated PPD reactions, d) measured heart and kidney size on X-rays and, e) described a model skin lesion (melanoma). Traditionally, measurement variation is taught in biostatistics or epidemiology courses using previously collected data. Use of these models enables students to produce their own data using measurements commonly employed by the clinician. The exercise provided material for a meaningful discussion of the implications of measurement error in clinical decision-making.

Clinical Competence↗
PubMedDate not supplied

Comparison of broth and filtration methods for culturing of intravenous fluids.

Ninety-six specimens of intravenous fluid solutions (D5/025 NS) were inoculated with S. aureus, E. coli, P. aeruginosa, K. pneumoniae, E. agglomerans, or C. albicans in concentrations of .1, 1, 10, or 10(2) organisms/ml. They were cultured in tubes containing 5 ml of double enriched broth and after passage through a .45 mu pore membrane filter. After 24 hours of incubation, broth cultures were 68% as sensitive as the filter cultures (p less than .001). At the lowest concentration (.1 organism/ml) broth cultures wer only 45% as sensitive as the membrane filter technique after 24 hours of growth (p less than .001). Membrane filters provide a rapid method to accurately detect and quantitate the presence of microbial contamination even at very low levels of concentration. The simplicity and accuracy of the filtration method offers the clinician a valuable adjunct in managing suspected cases of intravenous fluid related sepsis.

Bacteria↗
PubMedDate not supplied

Interobserver and method variability in tuberculin skin testing.

Accurate measurement and interpretation of tuberculin skin tests is essential both to avoid unnecessary prophylactic treatment with potentially hepatotoxic drugs and to ensure the proper institution of therapy in tuberculin-positive individuals. Although two methods are currently used for reading tuberculin skin tests, palpation and ballpoint, the optimal technique has not been established. We compared measurements obtained by each method on 101 patients tested with intermediate tuberculin purified protein derivative. Fifty-eight of these patients were also tested using Mono-Vacc. Excellent interobserver agreement among the five raters was demonstrated for both the palpation and ballpoint techniques. There was no significant difference between the two methods for any reader using the normal 10-mm cutoff point for a positive intermediate tuberculin purified protein derivative test. For any individual observer the decision as to whether the test was positive or negative was unaffected by the method in at least 93% of readings. We conclude that readings by physicians using palpation and ballpoint methods are comparable for clinical decision making.

Adolescent↗