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D E Low

Publications and source records attributed to D E Low.

At least 145 records · Page 8Linked to original sources
PubMed1994

Apparent lower rates of streptococcal toxic shock syndrome and lower mortality in children with invasive group A streptococcal infections compared with adults.

Since 1985 there have been worldwide reports of increases in severe invasive Group A streptococcal (IGAS) infections. We reviewed the charts of all children with IGAS infections (defined as isolation of Group A streptococcus from a normally sterile site) presenting to our institution over a 7-year period (January, 1985, to December, 1991) and the literature. Streptococcal toxic shock syndrome required hypotension and multisystem organ involvement. Twenty-four patients (mean age, 4.96 +/- 4.4 years) were identified with IGAS infection. One patient (presenting in 1989) met the criteria for probable streptococcal toxic shock syndrome and none died. Eight of 19 Group A streptococcal isolates tested were streptococcal pyrogenic exotoxin (SPE) A producers, most (90%) had the speC gene and all had the speB gene and produced the toxin. No M or T type predominated. The low rates of streptococcal toxic shock syndrome and fatalities among children with IGAS infection are consistent with other pediatric but not with adult series. The apparent differences in outcome of IGAS between children and adults were not explained by the virulence factors we examined and may warrant further investigation.

Adolescent↗
PubMed1994

Surveillance of susceptibility testing methodologies for Haemophilus influenzae in Canada, including evaluation of disk diffusion test.

We surveyed 75 clinical laboratories to determine if National Committee for Clinical Laboratory Standards (NCCLS) were being used for the susceptibility testing of Haemophilus influenzae. Of the 66 laboratories that performed susceptibility testing, all claimed to follow current NCCLS guidelines. However, upon further questioning, only 23, all of which used disk diffusion testing, accurately interpreted and followed the guidelines. Proficiency testing of 22 of these laboratories found that an unacceptable number of interpretive errors (> 10%) occurred. These results query the merit of routine disk diffusion susceptibility testing of H. influenzae to beta-lactam agents.

Anti-Bacterial Agents↗
PubMed1994

Efficacy of microbial identification system for epidemiologic typing of coagulase-negative staphylococci.

The lack of an adequate typing system hampers our understanding of the epidemiology of infections caused by coagulase-negative staphylococci (CoNS). CoNS have become recognized as important nosocomial pathogens and the principal cause of infections associated with invasive devices. Sensitive, specific, and convenient methods are needed to evaluate whether implementing infection control guidelines reduces the risk of nosocomial infections from CoNS and other pathogens. The Microbial Identification System (MIDI) (Microbial ID Inc., Newark, Del.), a semiautomated system for fatty acid methyl ester analysis, shows considerable promise for clinical and epidemiologic applications. Its predictive accuracy and reliability were tested by using epidemiologically related and replicated CoNS isolates as well as CoNS from epidemiologically unrelated clinical infections, which were obtained from five established hospital culture collections in diverse geographic locations. Two hundred isolates were fully characterized in 5 days by one person using MIDI, and the results were similar to those produced by more expensive and time-consuming conventional typing methods. MIDI appears to be a useful screening tool that could be used before more expensive and labor-intensive molecular methods. It offers important advantages to hospital epidemiologists and clinical microbiologists who must identify and type CoNS isolates.

Bacterial Typing Techniques↗
PubMed1994

Enterococcis: pathogens of the 90s.

The genus Enterococcus consists of at least 12 species, two of which account for over 95% of the clinically important strains, E faecalis (85%-90%) and E faecium (5%-10%). Despite their ubiquity and frequent isolation, they have not been thought to cause serious disease because they lack common virulence factors. Now, however, enterococci are regarded as true pathogens and are the second leading cause of nosocomial infections. This change results from their increasing antimicrobial resistance and the extensive use of antimicrobial drugs (for example-cephalosporins) that are not active against them. Serious infections should usually be treated with a beta-lactam and an aminoglycoside, but glycopeptides have been increasingly used during the last decade. Two novel resistance patterns of particular concern recently are high level aminoglycoside resistance (HLAR) and vancomycin resistance. The prevalence of HLAR is between 15% and 55%, and glycopeptide resistance has become widespread in various geographical areas. This poses a serious problem, as such resistance may spread to other Gram-positive organisms and is often associated with resistance to other antimicrobial drugs. This may theoretically result in groups of organisms for which there will be no effective antimicrobial treatment.

Abdominal Abscess↗
PubMed1994

Community-acquired pneumonia: the future of the microbiology laboratory: focused diagnosis or syndromic management?

The traditional classification of community-acquired pneumonia into typical and atypical pneumonia to facilitate successful empirical treatment is no longer optimal. An accurate prediction of cause and adequate empirical therapy cannot be provided with this approach in severely ill patients. There is an increasing spectrum of recognized treatable pathogens presenting as community-acquired pneumonia including Legionella species, Chlamydia pneumoniae, and Pneumocystis carinii in addition to the traditional community pathogens. The variability of presentation in severely ill or compromised hosts makes clinical prediction of cause inadequate. A more rational approach may involve the classification of patients by the severity of illness and underlying disease with little or no microbiological workup in mild illness unless the results will contribute to the epidemiological surveillance of resistance because these investigations have not been shown to affect outcome in this setting. Etiologic diagnosis should be more aggressively sought and the microbiology laboratory can be best used by providing the efficient and rapid diagnosis of this expanded range of pathogens in more severely ill patients. The mounting antimicrobial resistance of common pathogens such as Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus will require not only a critical review of empirical therapy, but an increased emphasis on epidemiological monitoring of resistance by laboratories and effective communication with clinicians.

Bacteria↗
PubMed1994

Management of the problem patient after antireflux surgery.

Long-term follow-up studies have confirmed the efficacy and durability of properly performed operations for gastroesophageal reflux; however, a significant number of patients develop trouble-some postoperative symptoms. Recurrent acid reflux and heartburn, dysphagia, gas bloat, diarrhea, and sliding and/or paraesophageal hernias may require medical or surgical intervention. Whereas some of these problems are transient, most require complete re-evaluations, and many require reoperations, ideally performed by surgeons with experience of these complex cases.

Gastroesophageal Reflux↗
PubMed1993

Emergence of vancomycin-resistant enterococci in New York City.

Enterococci, a common cause of nosocomial infection, are intrinsically resistant to most antimicrobials and readily acquire additional resistance. Vancomycin-resistant enterococci (VRE) have caused clusters of nosocomial infections since 1988. In April, 1991, the New York City Department of Health asked all city laboratories to submit suspected VRE isolates for confirmation. Clinical and epidemiological characteristics of the first 100 patients with VRE were identified, and antimicrobial susceptibility testing, restriction enzyme analysis, and DNA-DNA hybridisation with the vanA gene probe were done. From September, 1989, to October, 1991, 361 patients with VRE were identified at 38 hospitals. The number of hospitals reporting VRE increased from 1 in 1989 to 38 by October, 1991. 98% of 100 VRE infections were nosocomially acquired and 83% patients had received vancomycin and/or a cephalosporin in the 30 days before isolation of VRE. Of 23 isolates from 21 of the first 100 patients, 19 (83%) were resistant to all available antimicrobials. Four vanA probing patterns were noted, and restriction enzyme analysis of the 23 isolates revealed 14 strains. VRE have emerged rapidly in New York City. Molecular analyses suggest that a highly mobile genetic element--eg, a transposon--is responsible for the rapid spread of vancomycin resistance.

Aged↗
PubMed1993

Evidence for a clonal origin of methicillin resistance in Staphylococcus aureus.

Soon after methicillin was introduced into clinical practice in the early 1960s, resistant strains of Staphylococcus aureus (MRSA) appeared, bearing a newly acquired resistance gene, mecA, that encodes a penicillin binding protein, PBP2a. MRSA have spread throughout the world, and an investigation of the clonality of 472 isolates by DNA hybridization was performed. All 472 isolates could be divided into six temporally ordered mecA hybridization patterns, and three of these were subdivided by the chromomosomal transposon Tn554. Each Tn554 pattern occurred in association with one and only one mecA pattern, suggesting that mecA divergence preceded the acquisition of Tn554 in all cases and therefore that mecA may have been acquired just once by S. aureus.

Bacterial Proteins↗
PubMed1993

Detection of ampicillin resistance in Enterococcus spp. by disk diffusion and two commercial automated systems.

A total of 154 Enterococcus faecium and 48 Enterococcus faecalis isolates, 55% of which were ampicillin-resistant, were used to evaluate two commonly used automated systems, Vitek's GPS-TA card (bioMérieux, USA) and MicroScan's POS MIC Type 6 panel (Baxter Health-care, USA), and the NCCLS disk diffusion method for the detection of ampicillin resistance. MicroScan panels were read by the Walk/Away system and by visual inspection. The results were as follows: disk diffusion, 100% sensitive and specific; Vitek, 100% sensitive and 95% specific; and MicroScan, when read by the Walk/Away, 85% sensitive and 98% specific. When MicroScan was interpreted by visual inspection, however, sensitivity increased to 96%.

Ampicillin Resistance↗
PubMed1993

A cluster of surgical wound infections due to unrelated strains of group A streptococci.

Group A streptococci account for less than 1% of all surgical wound infections but are an important cause of nosocomial outbreaks. We report here a cluster of four group A streptococcal infections that occurred within an 11-day period on a single surgical service. The index case presented with toxic shock-like syndrome. Epidemiologic investigation did not identify any relationship between infections. Restriction endonuclease analysis and M and T typing found the four isolates to be unrelated. Restriction endonuclease analysis is a useful tool for determining relatedness of nosocomial isolates of group A streptococci.

Cluster Analysis↗
PubMed1993

Severe invasive group A streptococcal infections in Ontario, Canada: 1987-1991.

During the past few years, there has been an apparent increase in serious infections due to group A streptococci (GAS) worldwide. We describe our experience with severe invasive GAS infections in Ontario, Canada, during the past 5 years (February 1987 through December 1991). A case was defined as the isolation of GAS from blood or normally sterile tissue in association with hypotension (systolic blood pressure, < 90 mm Hg). Fifty cases were identified in patients ranging in age from 4 to 100 years (median age, 47 years); 29 (58%) of the patients died. A primary focus of infection was identified in 38 cases (76%), with soft tissue being the site involved most frequently (68%). No focus of infection was found in 12 patients, and 36 patients (72%) were bacteremic. Complications included acute respiratory distress syndrome (21 of 50), acute renal failure (20 of 50), hypocalcemia (19 of 24), elevated creatinine kinase values (21 of 27), coagulation abnormalities (15 of 21), and hepatitis (15 of 24). Eleven cases (22%) were nosocomial; one of these was secondary to another nosocomial case. Thirty-three isolates were available for M and T typing and for determination of the presence of the genes for streptococcal pyrogenic exotoxin (SPE). The most frequent types were M1T1 (10) and M12/T12 (8). Twelve isolates possessed the speA gene, and 16 isolates had the speC gene. Only three isolates possessed both speA and speC. All isolates possessed the speB gene.

Adolescent↗
PubMed1993

Canadian survey of antimicrobial resistance in Klebsiella spp. and Enterobacter spp. The Canadian Antimicrobial Resistance Study Group.

Increasing antimicrobial resistance has been reported for Klebsiella spp. and Enterobacter spp. The in-vitro activities of 14 antimicrobial agents against 656 clinical isolates of Klebsiella spp. and 630 isolates of Enterobacter spp. collected from seven cities in Canada were determined by microbroth dilution. There was no regional variation in the susceptibility patterns. Klebsiella spp. remain highly susceptible to most antimicrobials, only one isolate was resistant to third-generation cephalosporins. However, many isolates of Enterobacter spp. (> 16%) were resistant to the third-generation cephalosporins with marked cross-resistance to piperacillin (63.1%), piperacillin/tazobactam (44.9%), and aztreonam (76.6%). Gentamicin, tobramycin, imipenem, ciprofloxacin, cefepime, and cefpirome were consistently active against most isolates of Enterobacter spp. including those resistant to the third-generation cephalosporins.

Anti-Bacterial Agents↗
PubMed1993

Identification and characterization of multiple species of vancomycin-resistant enterococci, including an evaluation of Vitek software version 7.1.

A total of 374 clinical isolates of Enterococcus spp. were characterized to determine the species distribution and vancomycin resistance. The ability of the Vitek system (bioMerieux Inc, Hazelwood, St. Louis, Mo.) to identify enterococci to the species level and to recognize vancomycin resistance by using computer software version 7.1 was evaluated. Conventional methods were used for identification and agar dilution was used for susceptibility testing, the results of which were as follows (presented as number of vancomycin-resistant isolates/number of members of that species identified): 219/234 E. faecium, 9/112 E. faecalis, 2/3 E. mundtii, 0/1 E. durans, 0/1 E. hirae, 0/1 E. raffinosis, and 0/1 E. avium. Ten enterococci were in the vancomycin-intermediate category (six E. gallinarum, two E. casseliflavus, and one each of E. faecium and E. faecalis). The Vitek GPI card correctly identified 98% of E. faecium isolates, 99% of E. faecalis isolates, and only two isolates of other enterococcal species. The GPS-TA card was 98% sensitive and 95% specific for the detection of vancomycin resistance, generating a total of four very major (1.6%) and five minor errors (1.3%).

Drug Resistance, Microbial↗
PubMed1993

Utilization review of the use of BACTEC PLUS high-volume blood culture bottles.

The BACTEC PLUS 26 (NR26) (Becton Dickinson, Towson, Md.) high-volume blood culture bottle replaced the less expensive smaller-volume NR6A bottle in our hospital. An audit carried out several months after their introduction revealed that only 17.5% of the NR26 bottles received the required blood volume. Several audits and educational programs were required in order to achieve a compliance rate of > 60%.

Bacteremia↗
PubMed1993

Epidemiological typing of Moraxella catarrhalis by using DNA probes.

Small-fragment restriction enzyme analysis and DNA-DNA hybridization were used to compare 60 strains of Moraxella catarrhalis isolated from various geographic locations. Restriction enzyme analysis with HaeIII resulted in 46 different patterns, 7 of which were shared by more than one isolate. Hybridizations with two DNA probes resulted in 18 different patterns, 11 of which were shared by more than one isolate. Strains with the same restriction enzyme pattern always had the same hybridization pattern. However, of the 50 strains that shared the 11 hybridization patterns, 39 could be further differentiated by restriction enzyme analysis. We found that hybridization is a method that is specific for the epidemiological typing of M. catarrhalis, but because of limited sensitivity, combination with small-fragment restriction enzyme analysis may be necessary to better determine the relatedness of strains.

Bacterial Typing Techniques↗
PubMed1993

A study of the epidemiology of an endemic strain of staphylococcus haemolyticus (TOR-35) in a neonatal intensive care unit.

Coagulase-negative staphylococci (CNS) are among the most prevalent microorganisms that colonize and cause sepsis in neonatal intensive care units (NICU). We had previously identified a strain of CNS, Staphylococcus haemolyticus (TOR-35), in the NICU at Mount Sinai Hospital, that had been repeatedly isolated from blood cultures from neonates. We therefore carried out a prospective study to determine the frequency and time of colonization and the frequency of bacteremia in neonates over a 3.5 month period. This was accomplished by obtaining surface swabs within 1 h of birth and on days 3, 5, and 7 and by characterizing all blood culture isolates of CNS. We also determined what percentage of neonatal CNS bacteremias were due to this strain, between January 1, 1987 and December 31, 1990, by retrieving and typing all stock cultures of CNS from that period. All isolates were typed by species identification and antimicrobial susceptibility profile code. There were 76 (38%) neonates that became colonized with the TOR-35 strain at some time during their NICU stay. Lower birth weight was associated with colonization (p < 0.001), as was lower gestational age (p < 0.001). Only 1 neonate had a positive blood culture isolate for the TOR-35 strain during the prospective study. Of the 4 years of neonatal bacteremias that were studied retrospectively, there were 252 episodes of CNS bacteremia, of which 27 (11%) were due to the TOR-35 strain. The TOR-35 strain has become endemic in our NICU and appears to selectively colonize premature, low birth weight newborn infants, but only infrequently causes bacteremia.

Bacteremia↗
PubMed1993

The donor lung: infectious and pathologic factors affecting outcome in lung transplantation.

The prevalence of posttransplantation pulmonary infection and the importance of this complication with respect to morbidity in patients undergoing lung transplantation is significant. Over a 1-year period, case histories of all patients undergoing lung transplantation at Barnes Hospital, Washington University, were reviewed to examine the importance of organisms isolated in the donor lung in the development of subsequent invasive infection in transplant recipients. Twenty-eight of 29 bronchial washings (97%) taken from donors before retrieval grew at least one organism. The most common organisms identified were Staphylococcus and Enterobacter. In 12 of these cases (43%), similar organisms were isolated from the tracheobronchial tree of the recipients, and 6 of these recipients (21%) subsequently had invasive pulmonary infections as a result of the organism originally isolated in the donor. We recommend that antibiotic coverage in transplant recipients should be initiated on the basis of Gram stain results and modified on the basis of cultures obtained from the donor lungs. Pathologic analysis of donor lung tissue taken before transplantation was available in 12 cases. Four donors had histologic evidence of established pneumonia in the donor lung, and infections then developed in the recipients. One other patient who received a lung that had widespread bone marrow emboli and subsequent infarction later had a complete anastomotic dehiscence. An additional patient had profound early donor lung dysfunction without any evidence of rejection or infection. Pathologic findings from the donor in this case demonstrated preexistent acute vasculitis with emboli. We suggest that as preservation techniques improve, the opportunities for closer scrutiny of donor lung tissue before implantation will become increasing desirable and feasible.

Hospitals, University↗