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Biomedical subjects

L G Rubin

Publications and source records attributed to L G Rubin.

At least 19 recordsLinked to original sources
PubMed1998

Emergence of Candida parapsilosis as the predominant species causing candidemia in children.

An increase in the rate of isolation of Candida parapsilosis, relative to other Candida species, in our children's hospital led us to analyze the clinical and epidemiological variables associated with candidemia. We sought to determine if these variables are different for patients infected with C. parapsilosis. All episodes of candidemia occurring over a 7-year period were analyzed retrospectively. Of 81 episodes in 80 patients, 35 (43%) were in neonates, and 46 (57%) were in nonneonates. C. parapsilosis was isolated in 40 episodes (49%). C. parapsilosis was significantly more likely than non-C. parapsilosis species to be associated with prematurity (P = .001), presence of a central venous catheter (P = .002), and use of total parenteral nutrition (P = .03). C. parapsilosis has emerged as the predominant species in our children's hospital. The mortality rate associated with candidemia in children is lower than previously reported and may be associated with the high rate of isolation of C. parapsilosis.

Adolescent↗
PubMed1997

Relevance of the catheter hub as a portal for microorganisms causing catheter-related bloodstream infections.

Microorganisms causing vascular catheter-related sepsis gain access to the bloodstream through either the skin at the catheter insertion site or through the catheter hub. The catheter insertion site is probably the predominant portal for microorganisms in catheters in place for a short time, but the catheter hub may play an increasingly important role in infection in association with long-term catheters, particularly those that are subcutaneously tunneled. Although transient contamination of the catheter hub does not cause infection, certain microorganisms may migrate endoluminally and enter the bloodstream, causing bacteremia or fungemia.

Adult↗
PubMed1997

Duration of tick attachment as a predictor of the risk of Lyme disease in an area in which Lyme disease is endemic.

Animal studies have shown an exponential increase in the risk of Borrelia burgdorferi infection after 48-72 h of deer tick attachment. Persons with tick bites were prospectively studied to determine if those with prolonged tick attachment constitute a high-risk group for infection. Ticks were identified, measured for engorgement, and assayed by polymerase chain reaction (PCR) for B. burgdorferi DNA. Duration of attachment was determined from the scutal index of engorgement. Of 316 submissions, 229 were deer ticks; 14% were positive by PCR. Paired sera and an intact tick for determination of duration of attachment were available for 105 subjects (109 bites). There were 4 human cases (3.7% of bites) of B. burgdorferi infection. The incidence was significantly higher for duration of attachment > or =72 h than for <72 h: 3 (20%) of 15 vs. 1 (1.1%) of 94 (P = .008; odds ratio, 23.3; 95% confidence interval, 2.2-242). PCR was an unreliable predictor of infection. Tick identification and measurement of engorgement can be used to identify a small, high-risk subset of persons who may benefit from antibiotic prophylaxis.

Animals↗
PubMed1996

Meningococcemia.

Meningococcal infection is a contagious disease that is spread via the respiratory route through pharyngeal secretions. Clinical manifestations range from occult bacteremia to overwhelming septicemia or meningitis. Skin manifestations often develop and may be the first sign that leads to clinical suspicion of meningococcemia. Treatment consists of antibiotic therapy and supportive care, which may include aggressive fluid resuscitation, oxygen, ventilatory support, and inotropic support. The use of chemoprophylaxis and in certain circumstances vaccination are important in preventing secondary cases of meningococcal disease.

Bacteremia↗
PubMed1996

Randomized, double blind comparison of brand and generic antibiotic suspensions: I. A study of taste in adults.

BACKGROUND: A belief that brand oral liquid medications taste better than their generic counterparts may influence prescribing habits among pediatricians. METHODS: We undertook a prospective, randomized, double blinded, comparative evaluation of the taste of brand and generic erythromycin ethylsuccinate, cephalexin monohydrate, erythromycin ethylsuccinate/sulfisoxazole, penicillin V potassium and trimethoprim-sulfamethoxazole in 42 adult volunteers. Subjects tasted one class of brand and generic antibiotics and rated them according to smell, texture, taste and aftertaste. RESULTS: At least one generic preparation of cephalexin, erythromycin ethylsuccinate/sulfisoxazole and penicillin V potassium was rated equal in taste to the respective brand name products. However, brand erythromycin estolate and trimethoprim-sulfamethoxazole name brand suspensions rated significantly higher than the other products tested. CONCLUSIONS: Based on our results brand name oral antibiotic formulations do not necessarily taste better than their generic counterparts.

Administration, Oral↗
PubMed1996

Randomized, double blind comparison of brand and generic antibiotic suspensions: II. A study of taste and compliance in children.

BACKGROUND: The taste of oral liquid medications influences compliance in children. Generic preparations are prescribed to reduce cost and may taste worse than brand name products. METHODS: This was a prospective, randomized, double blind, crossover trial of the differences in taste and compliance between brand and generic antibiotic suspensions in children 3 to 14 years of age. Verbal and visual assessment methods were used to assess taste, and compliance was measured by the amount of drug returned after use. RESULTS: Ten children in each of the cephalexin and erythromycin-sulfisoxazole groups did not report that the brand and generic formulations tasted differently. Fifteen children thought that brand trimethoprim-sulfamethoxazole tasted better than the generic preparation. CONCLUSIONS: Brand name oral liquid antibiotics do not necessarily taste better than their generic counterparts. Despite preference for the taste of brand trimethoprim-sulfamethoxazole, all of the children in this study were compliant with both brand and generic medications.

Adolescent↗
PubMed1995

Synergy between protamine and vancomycin in the treatment of Staphylococcus epidermidis biofilms.

OBJECTIVES: To test for synergy between protamine and vancomycin by analyzing their bactericidal activities against slime-producing Staphylococcus epidermidis ATCC 35983 under planktonic and biofilm conditions. METHODS: We evaluated the activity of vancomycin and protamine separately against planktonic S epidermidis in broth by measuring the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for each agent according to the standard macrobroth dilution method. To assess the possibility of synergy between these two agents, planktonic S epidermidis was exposed to vancomycin and protamine together in varying concentrations. Biofilms containing S epidermidis were then prepared and subjected to incubation with vancomycin and protamine separately as well as combined in varying concentrations. The bacterial viability of S epidermidis in the planktonic and biofilm phases after exposure to these two agents was assessed by qualitative culture and determination of viable colony blots. RESULTS: Standard antibacterial susceptibility tests revealed that the MICs of protamine and vancomycin were 1 and 2 micrograms/mL, respectively, and their MBCs were 4 micrograms/mL. The MICs were unchanged when protamine and vancomycin were combined in varying concentrations. Neither agent exhibited significant bactericidal activity against S epidermidis in the biofilm phase at concentrations < or = 32 micrograms/mL. However, a combination of both agents, each at 32 micrograms/mL, resulted in a 7-log decrease in viable bacterial counts. CONCLUSIONS: Protamine alone exhibited significant antibacterial activity against planktonic S epidermidis. No synergy was noted between protamine and vancomycin against S epidermidis in the planktonic phase. However, synergy was demonstrated when a combination of protamine and vancomycin was used on S epidermidis in the biofilm phase. Thus, protamine shows promise as an adjunctive agent to vancomycin in the treatment of S epidermidis in biofilms.

Biofilms↗
PubMed1995

Phase-variable expression of the 145-kDa surface protein of Brazilian purpuric fever case-clone strains of Haemophilus influenzae biogroup aegyptius.

Clonally related strains of Haemophilus influenzae biogroup aegyptius have recently been associated with Brazilian purpuric fever (BPF). Antibodies to a 145-kDa minor outer membrane protein (P145) are bactericidal and protect against experimental bacteremia. To determine if P145 is conserved among case-clone strains, case-clone strains were screened for P145 expression. Assays of a large number of colonies of each strain using colony immunoblot revealed colonies reactive with anti-P145 sera in all 17 case-clone strains. P145 was expressed at a low frequency (0.08%-2.2% of colonies) in 14 strains and at a high frequency (> 98%) in 3 strains. Expression of P145 by reactive colonies was confirmed by SDS-PAGE. Also, anti-P145-nonreactive variant colonies of P145-expressing strains were detected in 0.4%-1.5% of colonies. These findings indicate P145 is conserved among BPF case-clone strains and is subject to phase-variable expression.

Animals↗
PubMed1995

Characterization of vancomycin resistance in Enterococcus durans.

During investigation of an outbreak of vancomycin resistant Enterococcus faecium in a paediatric hospital, an isolate of Enterococcus durans resistant to vancomycin, teicoplanin, ampicillin and highly resistant to gentamicin and streptomycin was found in the stools of a patient also colonized with a strain of E. faecium with the same resistance pattern. Minimal inhibitory concentrations of vancomycin and teicoplanin were 512 and 64 mg/mL, respectively. Resistance to vancomycin as well as high-level resistance to gentamicin was transferable to an E. faecium recipient strain. Both multiresistant E. faecium and E. durans isolates as well as the transconjugant presented only one plasmid. The vanA gene was detected and localized to the high molecular weight plasmid by DNA hybridization with a vanA gene probe. Growth in vancomycin resulted in induction of an approximately 40 kDa protein visible in membrane preparations from these cells. Genetic linkage between vancomycin and gentamicin resistance genes in the same plasmid is suggested.

Anti-Bacterial Agents↗
PubMed1995

Role of the 145-kilodalton surface protein in virulence of the Brazilian purpuric fever clone of Haemophilus influenzae biogroup aegyptius for infant rats.

Brazilian purpuric fever (BPF) is a fulminant infection associated with bacteremia with clonally related strains of Haemophilus influenzae biogroup aegyptius. Case-associated clone strains are more virulent for infant rats than are non-BPF case-associated H. influenzae biogroup aegyptius isolates. I sought to determine the possible role of P145, a 145-kDa surface protein of BPF case H. influenzae biogroup aegyptius clone isolates, in virulence. First, I compared the virulence of two case-associated clone isolates from the blood of children with BPF from Serrana, Brazil, which differed in P145 expression but were identical in all other phenotypic and genotypic characteristics studied. Twenty-four hours after intraperitoneal inoculation of infant rats, there was a significantly higher incidence (51 versus 26%; P = 0.035) and magnitude (2.9 +/- 5.8 versus 0.7 +/- 2.0 CFU/0.01 ml; P = 0.024) of bacteremia in rats inoculated with the P145-expressing strain. I next compared the virulence of a P145-expressing case-associated clone strain with two P145-nonexpressing phase variants of this strain. One variant exhibited a lower mean magnitude of bacteremia and one displayed a similar magnitude of bacteremia compared with that displayed the P145-expressing parental strain. P145-expressing revertants of the P145-nonexpressing strains exhibited the same virulence as the P145-negative variants from which they were derived. Colonies grown from blood cultures maintained the P145 phenotype of the inoculated strain. These results suggest that P145 expression does not contribute to the virulence of the BPF case clone strain for infant rats following intraperitoneal inoculation.

Animals↗
PubMed1995

Intravenous catheter-related infections.

Vascular catheter-related infection is an important cause of mortality and morbidity in hospitalized patients. The mean incidence of catheter-related bloodstream infection in hospitalized pediatric patients is 2.4 episodes per 1,000 days. Totally implantable central venous catheters may be associated with a lower risk of infection. Coagulase-negative staphylococci are the predominant cause and account for about one third of episodes of catheter-related bloodstream infection. The diagnosis of catheter-related bloodstream infection is often difficult because there are frequently no signs of inflammation around the catheter. Diagnosis depends on either a positive quantitative catheter culture yielding the same microorganism recovered from the bloodstream or differential quantitative blood cultures with significantly greater colony counts from blood drawn through the catheter than from blood drawn through a peripheral vein. Alternatively, probably catheter-related sepsis can be diagnosed when clinical sepsis is refractory to antimicrobial therapy but responds to catheter removal. Often these criteria are not met but catheter-related bloodstream infection is presumed because a common skin microorganism is isolated from the blood when clinical manifestations of bloodstream infection are present and there is no other apparent source of infection. Microorganisms causing catheter-related bloodstream infection gain access to the bloodstream predominantly from either the catheter insertion site or the catheter hub. Most catheter-related infections occurring shortly after catheter insertion probably gain access to the bloodstream by extraluminal migration along the catheter from the skin at the catheter insertion site. When catheters are in place for extended periods, especially greater than 30 days, the catheter hub probably plays a major role in microorganisms gaining access and then migrating endoluminally until reaching the bloodstream. Recently employed strategies for the prevention of catheter-related infections include topical antibiotics or antiseptics at the catheter insertion site, flush solutions containing vancomycin, and bonding antimicrobial agents to the catheter. Infection of peripheral and central venous catheters generally resolves after catheter removal. For tunneled silicone catheters, most episodes of catheter-related infection can be initially managed with antimicrobial therapy infused through the catheter without catheter removal. Staphylococcus aureus is generally more aggressive and associated with more complications than coagulase-negative staphylococci. Microorganisms that usually require catheter removal include Candida and Bacillus species. Adjunctive treatments of catheter infections include the use of urokinase. Catheter-related infection remains an important complication of vascular access. Novel prevention and treatment strategies are currently being investigated. In the near future bonding of antibiotics or other agents to catheters may become routine.(ABSTRACT TRUNCATED AT 400 WORDS)

Bacteremia↗
PubMed1993

A prospective study of the catheter hub as the portal of entry for microorganisms causing catheter-related sepsis in neonates.

The hypothesis that catheter-related sepsis (CRS) may be preceded by contamination of the catheter hub was tested in neonates with central venous catheters. Cultures of the catheter hub were obtained three times per week. One hundred thirteen catheters were placed in 88 patients. Of 35 episodes of sepsis, 28 were catheter-related, for a catheter sepsis rate of 1.03/100 catheter-days. CRS occurred in 26 (23%) of 113 catheters. In 10 of 28 episodes, the infecting microorganism was cultured from the hub before its culture from blood obtained at the time of clinical sepsis. In an additional 5 cases, a culture of the catheter hub at the time of clinical sepsis yielded the same isolate as the blood culture. Thus, 54% of episodes of CRS were preceded by or coincided with contamination of the hub. The catheter hub may be a major portal of entry for microorganisms causing sepsis in a neonatal intensive care unit.

Bacteremia↗
PubMed1993

Role of lipooligosaccharide in virulence of the Brazilian purpuric fever clone of Haemophilus influenzae biogroup aegyptius for infant rats.

Clonally related strains of Haemophilus influenzae biogroup aegyptius have recently been associated with Brazilian purpuric fever (BPF), a fulminant, systemic disease in children. Using an infant rat bacteremia model for BPF, we found that a rat blood-passaged BPF isolate of H. influenzae biogroup aegyptius was more virulent than the original strain was. When compared with the original strain, the animal-passaged variant was found to display an altered lipooligosaccharide (LOS) phenotype and to lack pili. To examine the role of LOS phenotype and pili in virulence, we isolated isogenic variants differing in LOS phenotype or expression of pili. The virulence of variants was compared by examining the results of blood cultures obtained 24 h after intraperitoneal inoculation with 10(5) CFU. Our results indicate that the LOS phenotype is a critical determinant of BPF clone virulence for infant rats. To a lesser extent, the absence of piliation and an undefined additional factor(s) contribute to virulence.

Animals↗
PubMed1993

Use of disinfectants to reduce microbial contamination of hubs of vascular catheters.

The vascular catheter hub is a potential portal of entry for microorganisms that cause catheter-related sepsis. Thus, a reduction in catheter hub contamination might reduce the incidence of catheter-related sepsis. To develop a regimen suitable for reducing microbial contamination of the catheter hub, we experimentally contaminated catheter hubs and assessed the efficacies of disinfectant solutions. Catheter hubs were incubated overnight with suspensions of Staphylococcus epidermidis, Pseudomonas aeruginosa, or Candida parapsilosis. After removal of unattached microorganisms, the catheter hubs were swabbed by rotating cotton swabs dipped in 1% chlorhexidine, 1% chlorhexidine in 70% ethanol, 70% ethanol, 97% ethanol, or normal saline. Posttreatment swabs of the catheter hub were obtained and cultured quantitatively. The cleaning regimens containing ethanol were the most effective. Seventy percent ethanol was more effective than chlorhexidine and is likely to be the safest treatment. We conclude that cleaning of the catheter hub with disinfectant can dramatically reduce microbial contamination.

Catheterization, Peripheral↗