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Biomedical subjects

L A Mermel

Publications and source records attributed to L A Mermel.

At least 19 recordsLinked to original sources
PubMed1996

Community outbreak of Legionnaires' disease: an investigation confirming the potential for cooling towers to transmit Legionella species.

In August and September 1993, we investigated an outbreak of legionnaires' disease in Fall River, Massachusetts, that involved 11 persons; the attack rate was highest in Flint, a community of Fall River. All cases were infected with Legionella pneumophila serogroup 1 (Lp-1). A case-control study revealed that cases were more likely than matched controls to have visited sites in neighborhood A of Flint. Environmental sampling in Flint found that four of nine aerosol-producing devices sampled contained legionellae; only two, conjoined cooling towers on building A, contained Lp-1. Three independent methods of subtyping--monoclonal antibody subtyping, arbitrary primer polymerase chain reaction, and pulsed-field gel electrophoresis--revealed that Lp-1 isolates from three cases with culture-positive legionnaires' disease matched those from the cooling towers on building A. Water samples from the homes of cases with culture-positive legionnaires' disease contained no legionellae. The results of this epidemiologic and laboratory investigation indicate that the cooling towers on building A were the source of the outbreak of legionnaires' disease and confirm the importance of cooling towers in the transmission of legionnaires' disease.

Adult↗
PubMed1996

Miller-Fisher syndrome associated with Campylobacter jejuni bearing lipopolysaccharide molecules that mimic human ganglioside GD3.

A Campylobacter jejuni strain of serotype O:10 was isolated from a patient who had Miller-Fisher syndrome. In its biochemical reactions and cellular morphology, the isolate was characteristic of typical C. jejuni. Antibodies against extracted lipopolysaccharide (LPS) were detected by passive hemagglutination in the acute- and convalescent-phase patient sera. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting with the O:10 antiserum, it was demonstrated that the strain possessed both low- and high-molecular-weight molecules. Chemical analysis of the LPS revealed that the core oligosaccharide has a terminal trisaccharide epitope consisting of two molecules of sialic acid linked to galactose, a structure reflecting the terminal region of human ganglioside GD3. As this trisaccharide is also present in LPS cores of serotype O:19 strains from patients with Guillain-Barré syndrome but not in cores of nonneuropathic C. jejuni, a possible role for the trisaccharide in the etiology of neuropathies is indicated, and a difference for distinguishing neuropathic strains from nonneuropathic strains may be the presence of a sialyltransferase required for the synthesis of this trisaccharide.

Acute Disease↗
PubMed1996

Bacteriology, safety and prevention of infection associated with continuous intravenous infusions.

There are over 50,000 intravascular catheter-associated bloodstream infections in the United States each year; globally, the number of these infections is likely to be much higher. At least half of these bloodstream infections are caused by staphylococci. The source of most pathogens causing endemic catheter-associated bloodstream infections is the catheter insertion site or the catheter hub, whereby microbes migrate into the bloodstream along the outside or inside of the catheter, respectively. The pathogenesis of epidemic intravascular catheter-related bloodstream infections is quite different. Epidemic bloodstream infections are due to manufacturer-related contamination or contamination that occurs at the location of catheter use, such as the hospital. These epidemics have most often been traced to contamination of intravenous solutions such as hyperalimentation or medications, blood products, contaminated cutaneous antiseptics or faulty decontamination of reusable devices. The prevention of infection associated with continuous intravenous infusion of factor VIII poses a number of challenges. Assurances of the sterility of the product is of paramount importance, as is proper storage of the product prior to use. Prevention of infection will further require particular attention to the conditions surrounding insertion of the catheter, including the optimal site of insertion, maximal barrier precautions and optimal disinfection of the insertion sites, and also to conditions surrounding maintenance of the device after insertion, including proper disinfection and aseptic techniques when manipulating the catheter hub, daily assessment of the insertion site, and maintaining scheduled changes of the intravenous tubing. With proper precautions, the risk of serious infection associated with a continuous infusion of factor VIII should be minimal.

Bacteremia↗
PubMed1995

The risk of midline catheterization in hospitalized patients. A prospective study.

OBJECTIVE: To assess the risk associated with midline catheter use in hospitalized patients. DESIGN: Prospective, consecutive enrollment. SETTING: A 719-bed university-affiliated hospital. PATIENTS: Patients were enrolled if they were likely to require at least 7 days of intravascular catheterization while hospitalized. MEASUREMENTS: Patients were monitored for adverse reactions. Catheter segment, insertion site, hub, infusate, and blood cultures were assessed. RESULTS: From February 1993 through June 1994, 251 Landmark midline catheters were inserted in 238 patients. One hundred forty catheter cultures were obtained from 130 patients who remained hospitalized for the duration of catheterization. For these 130 patients, the mean duration of catheterization was 9 days, the incidence of catheter colonization was 5.0 per 1000 catheter days, and the incidence of catheter-related bloodstream infection was 0.8 per 1000 catheter days. During the study period, two severe, unexpected adverse reactions occurred that may have been associated with the use of Landmark midline catheters; no such reactions were associated with the insertion of 58,580 Teflon peripheral catheters (P < 0.00001; exact 95% lower bound of the odds ratio, 68.9). Fifty-three similar reactions associated with Landmark midline catheters, including two deaths, have been reported to the Food and Drug Administration through June 1994. CONCLUSION: The risk for midline catheter-related infection is low. However, Landmark midline catheters are associated with life-threatening adverse reactions that are probably attributable to the catheter material itself.

Catheterization↗
PubMed1995

Controlling vancomycin-resistant enterococci.

After controlling an epidemic of vanB-type vancomycin-resistant Enterococcus faecium (VRE), we contained a subsequent vanA E faecium outbreak by using prospective laboratory-based surveillance, placing patients with VRE in private rooms, requiring the use of both gowns and gloves by all personnel entering the patients' rooms, and conducting prevalence surveys of patients on affected wards.

Anti-Bacterial Agents↗
PubMed1995

Association of Legionnaires' disease with construction: contamination of potable water?

OBJECTIVE: To describe two cases of nosocomial legionellosis and discuss the epidemiology of this infection. DESIGN: Potable water was collected from multiple sites. Patient and environmental isolates were characterized by the Legionella slide agglutination test and monoclonal antibody subtyping. Concordance among isolates was confirmed by pulsed-field gel electrophoresis (PFGE). SETTING: A 713-bed university-affiliated hospital. RESULTS: There was widespread contamination of potable water with Legionella pneumophila during a period of major construction; cooling towers were without growth of Legionella. One patient's isolate was the same by PFGE as the environmental isolate collected from the water faucet in his room. Control measures included superheating water used in all patient care areas to 75 degrees C for 72 hours and flushing superheated water through faucets and showers; cleaning shower heads with a sonicator washer; and raising the hot water storage tank temperature from 43 degrees C to 52 degrees C. After these interventions, repeat environmental cultures over the next 6 months were without growth of Legionella, and no further cases of nosocomial legionnaires' disease were documented. An association between legionnaires' disease and construction is postulated. Heightened surveillance and preventive measures may be warranted during periods of excavation on hospital grounds or when potable water supplies are otherwise shut down and later repressurized.

Aged↗
PubMed1995

The significance of changing needles when inoculating blood cultures: a meta-analysis.

Several recent studies have concluded that the changing of needles prior to inoculation of blood culture bottles does not reduce the contamination rate, although there is a consistent trend toward a reduction in number of contaminated cultures when the needle is changed prior to inoculation. We performed a meta-analysis of available studies prospectively comparing blood culture contamination rates with and without a needle change prior to inoculation. The overall weighted contamination rate when the needle was changed prior to inoculation was 2.0%, compared to 3.7% when the needle was not changed. Since an increase of approximately $5,000 in costs per patient is associated with a contaminated blood culture, this reduction in contamination rate could save approximately $85,000 for every 1,000 cultures performed. Our meta-analysis demonstrates reduced blood culture contamination when the needle used for phlebotomy is changed prior to inoculation. This should be considered when setting clinical policy regarding the performance of blood cultures.

Blood↗
PubMed1995

Comparison of Legionella pneumophila isolates by arbitrarily primed PCR and pulsed-field gel electrophoresis: analysis from seven epidemic investigations.

Arbitrarily primed PCR (AP-PCR) and pulsed-field gel electrophoresis (PFGE) subtyping were applied to clinical and environmental isolates from seven unrelated outbreaks of Legionnaires' disease. The patterns observed with each method matched patient isolates and the epidemiologically linked source of disease for each of the seven outbreaks. PFGE allowed more discrimination among various isolates, although AP-PCR usually gave comparable results. With both methods, certain patterns appeared to predominate in the comparison of the seven outbreaks. Of five clinical isolates not associated with the outbreaks, three gave profiles distinct from those observed in the outbreaks by both methods. This suggests that there are at least two predominant subtypes of Legionella pneumophila serogroup 1 associated with outbreaks. Investigations of outbreaks of legionellosis should employ either PFGE or AP-PCR in addition to monoclonal antibody analysis.

Bacterial Typing Techniques↗
PubMed1994

A pseudo-epidemic involving bone allografts.

Preimplantation cultures of four sterile bone allograft specimens grew Comomonas acidovorans and Pseudomonas species. An epidemiological investigation, including molecular subtyping methods, revealed that the allograft specimens were contaminated in a microbiology laboratory sonicator water bath.

Bone Transplantation↗
PubMed1994

IS6770, an enterococcal insertion-like sequence useful for determining the clonal relationship of clinical enterococcal isolates.

Enterococci expressing resistance to antimicrobial agents are increasingly important nosocomial pathogens. Effective strategies to prevent or abort outbreaks of resistant enterococcal infection will rely on an accurate understanding of the mechanisms by which these organisms spread. A 1065-bp insertion-like sequence (IS6770) is present in varying copy numbers in > 90% of enterococcal strains thus far examined. Hybridization patterns resulting from hybridization of enterococcal genomic DNA with an internal IS6770 probe vary considerably between unrelated strains and correlate well with results of pulsed-field gel electrophoresis and field-inversion gel electrophoresis in identifying clonal relationships among enterococcal isolates. IS6770 analysis of several outbreaks of resistant enterococci has confirmed the spread of single resistant clones rather than the emergence of resistance within the resident flora. These results suggest that IS6770 hybridization will be a useful tool for tracing the epidemiology of nosocomial enterococcal infections.

Amino Acid Sequence↗
PubMed1994

A prospective, randomized trial of gauze and two polyurethane dressings for site care of pulmonary artery catheters: implications for catheter management.

OBJECTIVES: To compare the safety of a conventional polyurethane transparent dressing and a novel highly permeable polyurethane dressing, as compared with standard gauze and tape, as site dressings for pulmonary artery catheters; and to rigorously determine the sources of bloodstream infections deriving from these catheters. DESIGN: Prospective, randomized, clinical trial. SETTING: General adult intensive care units (ICUs) in a university hospital. PATIENTS: A total of 442 adult patients with pulmonary artery catheters were studied. Two thirds of the catheters had been inserted in the operating room and one third had been inserted in an ICU. INTERVENTIONS: Patients were randomized at the time of pulmonary artery catheter insertion to have one of three dressing regimens: a) sterile gauze and tape (control), replaced every 2 days; b) a conventional polyurethane dressing, replaced every 5 days; or c) a highly permeable polyurethane dressing, also replaced every 5 days. MEASUREMENTS AND MAIN RESULTS: The origin of each catheter-associated bloodstream infection was sought by quantitatively culturing the skin of the insertion site and all potential sources on the catheter, including the hub and infusate from each lumen of the introducer sheath and the pulmonary artery catheter, and intravascular segments of the introducer sheath and pulmonary artery catheter. Bloodstream infection was confirmed by demonstrating concordance between isolates from the device and blood cultures by pulsed-field electrophoresis of genomic DNA, digested with low-frequency-cleavage, restriction endonucleases. One hundred thirty catheters were randomized to be dressed with sterile gauze and tape (control), 127 with the conventional polyurethane dressing, and 185 with the highly permeable polyurethane dressing. Patients and catheters in the three dressing groups were very comparable. Ninety-six (21.7%) of the 442 catheters studied showed colonization of the introducer sheath or the pulmonary artery catheter, and five (1.1%) catheters caused bloodstream infection. Catheter-related bloodstream infections were associated with concordant cutaneous colonization of the insertion site (n = 2), a contaminated catheter hub or infusate (n = 3), contamination of the extravascular segment of a repositioned catheter beneath the external protective plastic sleeve (n = 1), or hematogenous colonization of the catheter (n = 1). All pulmonary artery catheter-related bloodstream infections occurred with catheters (introducers) in place for > or = 5 days (p < .001). Cutaneous colonization under the dressing at catheter removal was lowest with gauze (10(1.3) colony-forming units), intermediate with the new highly permeable polyurethane dressing (10(1.8) colony-forming units; p < .01), and highest with the conventional polyurethane dressing (10(2.0) colony-forming units; p < .001). There were no significant differences in catheter colonization (20.0 to 25.2 cases per 100 catheters) or catheter-related bloodstream infection (0.8 to 1.6 cases per 100 catheters) between the three groups. CONCLUSIONS: The incidence of pulmonary artery catheter-related bloodstream infection has decreased over the past 5 yrs. Pulmonary artery catheter-related bloodstream infections originate from multiple sources, indicating that measures to prevent bacteremic infections of these devices must focus both on reducing cutaneous colonization at the insertion site and averting contamination of infusate and catheter hubs. Efforts should be made to limit the duration of catheterization with pulmonary artery catheters (including the introducer) to no longer than 4 days. The polyurethane dressings studied appear to be safe for use with pulmonary artery catheters and may be left on for up to 5 days between dressing changes.

Aged↗
PubMed1993

Detection of bacteremia in adults: consequences of culturing an inadequate volume of blood.

The yield of blood cultures depends on the volume of blood cultured. We recently discovered that 15% of blood-culture specimens from adults in our hospital were being collected in 3.5-mL pediatric tubes and that another 5%, drawn in 10-mL adult tubes, contained less than 5 mL of blood. A comparison of 829 matched pairs of standard-volume (mean, 8.7 mL) and low-volume (mean, 2.7 mL) blood cultures showed that standard-volume cultures had a substantially higher detection rate for bloodstream infection than did low-volume cultures (92% compared with 69%; difference, 23% [95% CI, 9% to 37%]; P < 0.001). Our data, together with an analysis of previous studies, show that the yield of blood cultures in adults increases approximately 3% per millilitre of blood cultured. A survey of 158 U.S. clinical microbiology laboratory directors in the American Society of Clinical Pathologists showed that only 20% of 71 responding laboratories record the volume of blood submitted for culture and that the practice of culturing suboptimal volumes of blood from adults is widespread. Clinical laboratories should routinely monitor the volume of blood cultured as a quality-assurance measure. Blood-culture specimens from adults should not be drawn using small pediatric tubes.

Adult↗
PubMed1993

Surface antimicrobial activity of heparin-bonded and antiseptic-impregnated vascular catheters.

Most Swan-Ganz pulmonary artery catheters have heparin bonded to the surface with benzalkonium chloride, a cationic surfactant, to reduce thrombosis. Since benzalkonium is bactericidal, the antimicrobial activity of heparin-bonded pulmonary artery catheters was investigated in an in vitro assay. Each catheter exhibited activity against a wide variety of potential microbial pathogens, including Candida albicans. The magnitude of activity against individual organisms correlated strongly with their in vitro susceptibility to benzalkonium chloride (r = .94, P < .002). A chlorhexidine-silver sulfadiazine-impregnated catheter exhibited even greater activity than the heparin-bonded catheters (P = .01). When exposed to serum for 24 h, heparin-bonded catheters lost > or = 50% of their antimicrobial activity, whereas the activity of the chlorhexidine-silver sulfadiazine-impregnated catheter was minimally affected. The fortuitous surface antimicrobial activity of heparin-bonded catheters may account for the low incidence of catheter-related bacteremia (mean, 1.0%) compared with Swan-Ganz catheters of the same materials but not coated with benzalkonium-heparin (mean, 2.8%).

Benzalkonium Compounds↗
PubMed1992

Nosocomial sepsis due to Serratia odorifera biovar 1.

Serratia odorifera biovar 1 has been infrequently isolated from humans, and infection caused by this organism rarely has been documented. We report what is, to our knowledge, the first case of nosocomial sepsis due to S. odorifera biovar 1 and review the literature for which English-language abstracts were available on this organism. We also discuss the biochemical characteristics and the antimicrobial susceptibility pattern of this organism.

Aged↗
PubMed1991

The pathogenesis and epidemiology of catheter-related infection with pulmonary artery Swan-Ganz catheters: a prospective study utilizing molecular subtyping.

To delineate the pathogenesis and epidemiology of catheter-related infection with Swan-Ganz pulmonary artery (PA) catheters, a prospective clinical study of hospitalized adult medical and surgical patients was done. Role of catheter material was assessed by randomizing insertions to heparin-bonded PA catheters made of polyvinylchloride or polyurethane. Sources of infection and pathogenesis were studied by culturing skin, the introducer, the PA catheter tip, all hubs, infusate from each lumen, and the extravascular portion of the PA catheter beneath the external protective plastic sleeve. Concordance between isolates from sources and infected catheters was determined by speciation, antibiogram, and for coagulase-negative staphylococci, plasmid profile analysis. Risk factors for infection were determined by stepwise logistic regression. Overall, 65 (22%) of 297 Swan-Ganz catheters showed local infection of the introducer (58 catheters) or the intravascular portion of the PA catheter (20 catheters); only two catheters (0.7%) caused bacteremia. Eighty percent of infected Swan-Ganz catheters (the introducer or PA catheter) showed concordance with organisms cultured from skin of the insertion site, 17% with a contaminated hub and 18% with organisms contaminating the extravascular portion of the PA catheter beneath the sleeve. Isolates from infected PA catheters were most likely to show concordance with concomitantly infected introducers (71%). Cutaneous colonization of the insertion site with greater than 10(2) cfu/10 cm2 (relative risk [RR] 5.5; p less than 0.001), insertion into an internal jugular vein (RR 4.3; p less than 0.01), catheterization greater than 3 days (RR 3.1; p less than 0.01), and insertion in the operating room using less stringent barrier precautions (RR 2.1; p = 0.03) were each associated with a significantly increased risk of catheter-related infection. The risk of bacteremic infection with Swan-Ganz catheters is now low, in the range of 1%, with reasonable care. Swan-Ganz catheters are vulnerable to contamination from multiple sources, but the patient's skin is the single most important source of organisms causing invasive infection, which in most cases involves the introducer rather than the PA catheter. Heavy colonization of the insertion site, percutaneous insertion in the internal jugular vein rather than subclavian vein, catheterization longer than 3 days, and insertion with less stringent barrier precautions significantly increase the risk of catheter-related infection. These findings hold promise for application to management of Swan-Ganz catheters and research in catheter design to reduce the risk of catheter-related infection.

Adolescent↗