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Biomedical subjects

W G Barnes

Publications and source records attributed to W G Barnes.

At least 37 records · Page 2Linked to original sources

Clinical significance of serotype, biotype, and beta-lactamase production of respiratory isolates of Hemophilus influenzae.

The correlation between clinical significance and serotype, biotype, and beta-lactamase production of 101 respiratory isolates of Hemophilus influenza from nonbacteremic patients was determined. Six of 33 (18.2%) isolates from patients with definite or probable infection were serotypable; only two of 67 (3%) isolates from colonized patients were serotypable. Eight-seven and one-half per cent of the serotypable strains were biotypes I or IV; 78.8% of nonserotypable strains were biotypes II, III, or V. Biotype distribution among isolates from patients with definite or probable infection were similar to isolates from colonized patients. beta-lactamase production was not helpful in evaluating clinical significance. Nonserotypable H. influenzae is an important cause of nonbacteremic pneumonia in elderly men.

Adult↗

Nasal dermatitis in the Mongolian gerbil.

The prevalence of nasal dermatitis in two breeding colonies of Mongolian gerbils was determined; 56 of 302 (18.5%) were affected in Colony A, and 2 of 54 (3.7%) were affected in Colony B. The presence of nasal lesions did not correlate with sex, tail barbering, or epilepsy. There was a positive correlation between presence of nasal lesions and forepaw dermatitis, periocular alopecia, and protrusion of the nictitating membrane. Lesions were most common in the superior labial and lateral nasal regions. Histopathologic changes in the nasal area included acanthosis, mild hyperkeratosis, and inflammation of the dermis. Isolates of beta-hemolytic Staphylococcus aureus of several phage types were cultured from the nasal area of affected and nonaffected animals in both colonies. Staphylococcus saprophyticus isolates were associated with the development of early nasal lesions.

Animals↗

Generalized exfoliation associated with Staphylococcus aureus infection.

A 67-year-old man presented with a rash that was refractory to systemic corticosteroid therapy. Physical examination revealed sloughing skin on his hands, soles, and lower extremities. Stroking involved and uninvolved skin produced Nikolsky's sign. Skin biopsies revealed the plane of cleavage to be in the basal epidermal layer. Cultures of the patient's skin, blood, nose, and throat grew Staphylococcus aureus. These isolates produced an epidermal toxin that caused Nikolsky's sign in neonatal mice. The toxin caused cleavage in the basal epidermal layer of neonatal mice, was heat labile, and was not neutralized by exfoliatin antitoxin.

Aged↗

Nosocomial Aeromonas hydrophila cellulitis and bacteremia in a nonimmunocompromised patient.

An elderly man, without heat in his home for two days, presented with cold, painful, swollen feet. Second-degree frostbite was present. After having moist packs applied to his feet for five days, the patient became febrile and hypotensive, and wet gangrene necessitated left below-knee and right above-knee amputations. Aeromonas hydrophila was isolated from the patient's blood and cultures of the pedal wounds. An etiologic role of the moist pack therapy is postulated.

Aeromonas↗

Examination of major disagreements in susceptibility test results by Autobac-1 and MS-2.

Major disagreements between two automated susceptibility test instruments, Autobac-1 and MS-2, generated from 4,213 tests on 630 bacterial isolates, were analyzed. The major disagreement rate between the instruments was only 7.4%. The highest major disagreement rates for bacteria were with Staphylococcus epidermidis, enterococci, gram-positive bacilli, and Providencia species, and those for antibiotics were with ampicillin and penicillin G. With most other bacteria and antibiotics, the instruments disagreed at a rate less than 10% and frequently at a rate less than 4%. However, 32 specific bacterium-antibiotic combinations exceeded a 10% rate. Possible reasons for some of these higher disagreement rates are discussed. Reconciliation of instrument results with the standard agar disk diffusion result for each major disagreement revealed that about 15% were irreconcilable and, of the remaining 259, 177 agreed with MS-2 and 82 agreed with Autobac-1. Major disagreements between instruments seemed random, but there appeared to be tendencies, with certain bacteria and certain antibiotics, for MS-2 to detect susceptible reactions more consistently than resistant ones and for Autobac-1 to detect resistant reactions more consistently than susceptible ones.

Anti-Bacterial Agents↗

Susceptibility of Legionella pneumophila to three cooling tower microbicides.

Investigation of epidemic outbreaks of Legionnaires disease by Center for Disease Control personnel has resulted in the isolation of Legionella pneumophila from water in the air-conditioning cooling towers or evaporative condensers at the site of the outbreak. It is suspected that improperly maintained open, recirculating water systems may play a role in the growth and dissemination of this pathogen. The objective of this study was to determine the antimicrobial activity of three chemically different, commercially available, cooling tower microbicides against L. pneumophila. Using two in vitro test systems, a combination of N-alkyl dimethyl benzyl ammonium chloride and bis (tri-n-butyltin) oxide was found to kill L. pneumophila at a concentration 25 times less than the minimum recommended use concentration, whereas N-alkyl 1,3-propanediamine and methylene bis (thiocyanate) were active at concentrations equal to or greater than the concentrations recommended for use by the manufacturer.

Benzalkonium Compounds↗

Misdiagnosis caused by fungal contaminant in a histological stain solution.

Silver stains on tissue and cytology specimens are important in the evaluation of patients with suspected fungal infections. Care must be taken, however, to prevent misinterpretation of contamination artifacts. Two cases presenting such a problem are reported. The first patient had granulomatous leg lesions that microscopically showed characteristics of erythema induratum but with budding yeastlike organisms demonstrated by Grocott methenamine silver stain. Cultures and subsequent biopsies were negative for fungi. The second patient had a steroid-dependent chronic obstructive lung disease, and during evaluation for possible Pneumocystis carinii pneumonia, the Grocott methenamine silver stain on expectorated sputum showed budding yeastlike organisms. Sputum cultures were negative for fungi. Examination of the two Grocott light-green counterstain solutions demonstrated black, budding yeast cells similar to those seen in the specimens from the patients. Culture of the counterstain grew Exophiala (Phialophora) jeanselmei. Further studies revealed that this cause of misdiagnosis could be prevented by either filtering or adding thymol to the counterstain solution. Care regarding contamination of histological stain solutions is emphasized.

Granuloma↗

Clinical evaluation of automated antibiotic susceptibility testing with the MS-2 system.

The MS-2 (Abbott Laboratories) system for automated antimicrobial susceptibility testing was evaluated for both accuracy and general utility in our clinical laboratory. A total of 984 fresh clinical bacterial isolates (745 gram-negative, 239 gram-positive) were tested with the MS-2 system, and results were compared directly with those from a conventional agar disk diffusion method. Discrepancies between the two methods were categorized as very major, major, and minor. For gram-positive isolates, full accord (all discrepancies considered) was 91.6%, and essential accord (minor discrepancies not included) was 96.2%. With gram-negative isolates, full accord was found to be 93.9%, with essential accord of 97.9%. Aggrement as a function both of organism group and of antimicrobial agent was determined. Full accord of 90% or more was found for all major organism groups tested, with the exception of enterococci, where discrepant results between the two methods were observed. Mean test time for all isolates tested was 4.3 h. The MS-2 was found to be an accurate and highly automated instrument which required minimal technician time and was readily adaptable to work flow in our clinical laboratory.

Anti-Bacterial Agents↗

Pseudobacteremia caused by Clostridium sordellii.

Thirteen of 280 (4.6%) blood cultures collected over a 12-day period were positive for Clostridium sordellii, a spore-forming anaerobe, rarely considered a human pathogen. Nosocomial bacteremia and intrinsic contamination of material used to culture blood were excluded as the source of the organism. Contaminated tincture of thimerosal used to swab the rubber stoppers of blood culture bottles prior to venting (aerobic) or during blind subculturing after 24 hours of incubation (anaerobic) in the clinical microbiology laboratory was determined to be the cause of the pseudobacteremia. After appropriate safe-guards were implemented, we have continued to use tincture of thimerosal for these procedures with no further growth of C sordellii from blood cultures. The importance of less-conspicuous steps in the routine processing of culture material have been reemphasized.

Blood Specimen Collection↗

Complications with heparin-lock needles.

The incidence of phlebitis was determined for heparin-lock needles after use of three different methods of skin preparation and follow-up care. Phlebitis was significantly more frequent when iodophor solution and iodophor ointment, respectively, were used than when iodophor solution alone was used for heparin-lock needles in use longer than 48 hours, with more than ten manipulations of the systems, and when only one drug was infused through the systems. Iodophor solution skin preparation followed by daily application of iodophor solution is recommended to minimize the occurrence of associated phlebitis.

1-Propanol↗

A Pseudomonas pyocin typing method applicable to the clinical laboratory.

A new pyocin typing method for the identification of specific strains of Pseudomonas aeruginosa is described. The method involves a bilayer agar technique in which the pyocin produced by the organism diffuses from the top agar layer number 2 through a filter paper into the bottom agar layer number 1. The filter paper permits the removal of agar layer number 2 and exposes layer number 1 which is then streaked with the indicator strains. Pyocin typing of fifty clinical isolates using both the bi-layer method and the scrap-chloroform reference method of Gillies and Govan produced identical typing results. A total of 375 clinical isolates has been typed by this inexpensive and time-saving bi-layer agar method.

Agar↗

Clinical significance of citrobacter isolates.

Little is know about the clinical significance of isolating Citrobacter in the clinical laboratory. During a one-year period, 116 Citrobacter isolates were obtained from 77 patients with 83 suspected infectious episodes. The majority of the suspected infectious episodes involved the urinary tract (45%) or respiratory tract (41%). Citrobacter diversus was associated with 42% of the episodes, Citrobacter freundii with 29%, and Citrobacter species with 29%. In 42% of the suspected infectious episodes, the presence of Citrobacter was considered clinically significant; in the others, the significance of the Citrobacter isolates was indeterminate or considered to be commensal. Two thirds of the significant infections were hospital-acquired. Most patients (73%) from whom Citrobacter was cultured had underlying diseases or factors predisposing to infection. These data suggest that Citrobacter is a cause of significant opportunistic nosocomial infection in the hospital.

Adult↗

Community-acquired bacteremic Achromobacter xylosoxidans type IIIa pneumonia in a patient with idiopathic IgM deficiency.

A man was hospitalized with bacteremic Achromobacter xylosoxidans type IIIa pneumonia. The authors are aware of no previously reported similar infections caused by this bacterium. A clinical cure was achieved with a combination of carbenicillin and kanamycin therapy. Microtiter susceptibility testing revealed that carbenicillin was the antibiotic to which A. xylosoxidans IIIa was most sensitive (minimal inhibitory concentration, 1.6 microgram/ml) and that synergy between carbenicillin and kanamycin existed. During the patient's hospitalization, deficiency of IgM (21 mg/dl) was found. Specific serum activity against A. xylosoxidans IIIa was detected by the agglutination method. Specific anti-A. xylosoxidans IIIa IgG, but not IgM, was detected by indirect immunofluorescence. It appears that a defect in immunologic recognition of A. xylosoxidans IIIa as an invasive bacterium, a defect in synthesis of specific IgM, or both, contributed to this patient's infection.

Agglutination Tests↗

Zygomycosis of the maxillary sinus and palate caused by Basidiobolus haptosporus.

Basidiobolus haptosporus is known to cause subcutaneous zygomycosis in tropical Africa and Asia. We cared for a 49-year-old hyperglycemic, asplenic man who had never traveled outside the United States and who was seen initially for a painless palatal ulcer with cutaneous hypesthesia of the right cheek and upper lip. An invasive process involved the right middle nasal turbinate, maxillary antrum, maxillary division of the trigeminal nerve, and bony palate. Histological examination of biopsy tissue showed necrotizing granulomata with broad, nonseptate hyphae. Basidiobolus haptosporus was cultured from this tissue. Various laboratory studies revealed no immunologic defect and his lesions responded to therapy with amphotericin B. To our knowledge, this represents the first case of zygomycosis caused by B haptosporus in the Americas and the first culture-documented case of invasive mycosis caused by this mold.

Fungi↗

The absence of bacteremia during colonoscopy.

Seventy-nine blood cultures were obtained from 15 patients undergoing diagnostic colonoscopy. Aerobic and anaerobic culture technics showed no evidence of bacteremia during or after the procedure. The colonoscope was passed to the cecum in 12 of the 15 patients. The time of the procedure varied from 15-60 minutes with an average of 30 minutes. The results of this study supplies further evidence that bacteremia during colonoscopy is an infrequent occurrence.

Colon↗