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Biomedical subjects

J W Warren

Publications and source records attributed to J W Warren.

At least 91 records · Page 5Linked to original sources

MR/K hemagglutination of Providencia stuartii correlates with adherence to catheters and with persistence in catheter-associated bacteriuria.

Providencia stuartii was the most prevalent bacterial species isolated, for one year, from weekly urine specimens from 51 long-term catheterized patients. Significantly more strains causing bacteriuric episodes of long duration expressed MR/K (mannose-resistant/Klebsiella-like) hemagglutination (74%) than did those causing episodes of short duration (26%; P = .004). Isolates expressing MR/K hemagglutinin bound in higher numbers to catheter material (P = .023) than did those not expressing this hemagglutinin. Significantly more strains causing bacteriuric episodes of short duration expressed the mannose-sensitive (MS) hemagglutinin (43%) than did those causing episodes of long duration (7%; P = .014). Isolates expressing MS hemagglutinin bound significantly more 125I-labeled Tamm-Horsfall protein (THP) than did isolates not expressing this hemagglutinin (P = .0001). Our results indicate that MR/K hemagglutinin plays an important role in the ability of P. stuartii to persist and suggest that MR/K adheres to the catheter. Conversely, MS hemagglutinin binds to THP and may prevent persistence of P. stuartii in the catheterized urinary tract.

Aged↗

Acute pyelonephritis associated with bacteriuria during long-term catheterization: a prospective clinicopathological study.

Bacteriuria is virtually universal in long-term catheterized patients. This blinded autopsy study of 75 aged nursing home patients demonstrated that acute inflammation of the renal parenchyma was present in 38% of patients with a urinary catheter in place at death versus 5% of noncatheterized patients (P = .004). Of a number of clinical and demographic variables studied, only catheterization was significantly related to acute renal inflammation. Acute cystitis was uncommon, but each case was associated with inflammation of at least one kidney. The majority of kidneys showing acute inflammation (21 [68%] of 31) were not accompanied by acute pyelitis. Acute renal inflammation with or without pelvic inflammation is a common finding in nursing home patients dying with urethral catheters in place. This finding provides additional support for the development of alternatives to the indwelling urethral catheter.

Acute Disease↗

Commonly used methods of estimating creatinine clearance are inadequate for elderly debilitated nursing home patients.

We evaluated the Jelliffe and the Cockcroft and Gault methods of estimating creatinine clearance in elderly nursing home patients (65 years) with chronic indwelling urethral catheters. Although these relationships have been prospectively validated in hospitalized and ambulatory populations previously, we found that they produced poor estimates of creatinine clearance in this patient group. For the Jelliffe method, 11 of 19 estimates were 20% or greater from the measured value; 10 of 11 poor estimates were high. The Cockcroft-Gault method had 10 of 19 estimates 20% or greater from the measured value with 8 of 10 of the poor estimates being high. An altered relationship between body weight, muscle mass, and daily creatinine production is the most likely explanation for the bias in these creatinine-clearance estimations. New estimates of the relationships between age, weight, serum creatinine, and creatinine clearance need to be developed for this population.

Aged↗

Long-term urethral catheters in older women.

If other methods of managing urinary incontinence fail, a long-term urethral catheter may be considered. Bacteriuria invariably develops in patients with a catheter in place for 30 days or more. With long-term catheterization, bacteriuria becomes polymicrobial, including familiar and unfamiliar uropathogens. Some febrile episodes, particularly those with high temperatures, can be fatal.

Aged↗

Long-term catheter-associated bacteriuria: species at low concentration.

Polymicrobial bacteriuria in patients with long-term (greater than or equal to 30 days) indwelling urethral catheters is common and is associated with potentially serious acute and long-term complications. The dynamics of organisms at low concentration (less than 10(5) cfu/mL) in this setting has not been well-characterized; however, in patients with short-term catheters organisms initially present at low concentration (less than 10(5) cfu/mL) usually grow to high concentration (greater than or equal to 10(5) cfu/mL). At the time of catheter replacement for 7 long-term catheterized patients who were not receiving antibiotics, we identified all species at greater than or equal to 10(2) cfu/mL in fresh urine aspirated from the old indwelling catheter and the new sterile replacement catheter and then determined which of these species were present at high concentration two weeks later. A total of thirty-seven species, nineteen at high and eighteen at low concentration were detected in either the old or the new catheters. Eighteen of the nineteen initially detected at high concentration but only one of the eighteen initially detected at low concentration (p less than 0.001) were present at high concentration two weeks later. In patients with long-term indwelling urethral catheters, the number and multiplicity of species causing bacteriuria at low concentration rival that of species at high concentration; however, species at low concentration usually do not grow to high concentration in the presence of other species at high concentration.

Bacteriuria↗

Uropathogenicity in rats and mice of Providencia stuartii from long-term catheterized patients.

Providencia stuartii, a frequent and persistent isolate from the urinary tract of chronically catheterized elderly patients, is multiply antibiotic resistant and may cause fatal bacteremia in those patients. We studied P. stuartii strains in rats and mice to determine differences in uropathogenicity. Strains studied varied in expression of factors which contribute to pathogenicity of other bacterial species. Urinary tract responses following challenge with P. stuartii strain HO (factors expressed) were similar to responses reported for uropathogenic E. coli strains both in bacterial persistence and histologic change. In animals similarly challenged with P. stuartii strain RO (factors not expressed), responses were similar to those reported for non-uropathogenic E. coli strains. Results indicate that: a) animal model studies may be useful in differentiating P. stuartii strains based on uropathogenicity, b) P. stuartii uropathogenicity may be related to identifiable factors associated with virulence in other species, and c) the CBA mouse model appears to be the most suitable for studies of P. stuartii uropathogenicity.

Animals↗

Fever, bacteremia, and death as complications of bacteriuria in women with long-term urethral catheters.

Numbers of nursing home beds now exceed hospital beds in the United States and are usually occupied by women. Urinary incontinence is very common and may be managed with long-term urethral catheters. Bacteriuria invariably results, yet its clinical consequences are not well known. We studied 47 catheterized and bacteriuric women for almost 25 patient-years. The incidence of febrile episodes of possible urinary origin was 1.1 episodes/100 patient-days. Because these were diagnoses of exclusion, even this low incidence may be an overestimate. Most of these episodes were of less than or equal to 38.3 C (101.0 F), lasted for less than one day, and resolved without antibiotic therapy. Six deaths, half the total from all causes, occurred during these episodes, an incidence 60 times that during afebrile periods. Deaths and bacteremias were significantly associated with episodes of greater than or equal to 38.8 C (102.0 F). In the individual patient, these risks should be weighed against benefits of patient comfort, family satisfaction, and prevention and management of decubitus ulcers.

Aged↗

Recruitment of long-term care facilities for research.

We report the successful recruitment of a stratified random sample of nursing homes in the state of Maryland into three research studies funded by the National Institute on Aging. These studies examine the prevalence of infections and urinary tract instrumentation and the incidence of antimicrobial use in nursing home residents. Following selection of a facility, the administrator was telephoned and a meeting at the home was requested. At this meeting, the project was explained in detail using a packet of promotional information which included a project summary, a listing of project staff and their qualifications, and letters of support from influential organizations. A total of 61 eligible facilities were contacted in order to achieve a group of 53 participating homes with approximately 5000 beds. One hundred percent cooperation was achieved from all strata except small (less than or equal to 50 beds) proprietary comprehensive care facilities, and homes with both comprehensive and domiciliary beds. A direct, personal approach, backed by a carefully prepared study information and the support of medical and nursing home organizations resulted in successful recruitment of 53 (87%) of 61 homes sampled.

Aged↗

A practical method of estimating stature of bedridden female nursing home patients.

Accurate measurement of stature is important for the determination of several nutritional indices as well as body surface area (BSA) for the normalization of creatinine clearances. Direct standing measurement of stature of bedridden elderly nursing home patients is impossible, and stature as recorded in the chart may not be valid. An accurate stature obtained by summing five segmental measurements was compared to the stature recorded in the patient's chart and calculated estimates of stature from measurement of a long bone (humerus, tibia, knee height). Estimation of stature from measurement of knee height was highly correlated (r = 0.93) to the segmental measurement of stature while estimates from other long-bone measurements were less highly correlated (r = 0.71 to 0.81). Recorded chart stature was poorly correlated (r = 0.37). Measurement of knee height provides a simple, quick, and accurate means of estimating stature for bedridden females in nursing homes.

Aged↗

Urease-positive bacteriuria and obstruction of long-term urinary catheters.

Long-term urethral catheterization (greater than or equal to 30 days), a management technique for urinary incontinence, results in polymicrobial bacteriuria. We frequently found urease-producing bacteria: of 1,135 weekly urine specimens from 32 long-term-catheterized patients, 86% had urease-positive bacterial species at greater than or equal to 10(5) CFU/ml. The most common species were Proteus mirabilis and Morganella morganii, each found in over half the specimens. P. mirabilis, but not other urease-positive species, was significantly associated with the 67 obstructions observed in 23 patients. M. morganii had a more complex association and in some way may protect the catheter from obstruction.

Aged↗

Expression of type 1 fimbriae may be required for persistence of Escherichia coli in the catheterized urinary tract.

Long-term urinary catheterization results in polymicrobial bacteriuria and is complicated by fever, bacteremia, acute pyelonephritis, and death. Escherichia coli is a common urine isolate from catheterized patients and can persist for months. We hypothesized that fimbria-mediated adherence contributes to its persistence. For 1 year, urine specimens were collected from 51 patients greater than or equal to 65 years of age who were catheterized for greater than or equal to 30 days. E. coli was isolated at greater than or equal to 10(5) CFU/ml from 447 (36%) of 1,230 weekly urine specimens from 26 patients. Week 1 isolates from 52 definable episodes were tested for hemagglutination, hybridization with gene sequences from the pil and pap operons, in vitro adherence to catheter material, binding of 125I-labeled Tamm-Horsfall protein, hemolysin and colicin V production, and serum resistance. The proportions of isolates of short (1 week only), medium (2 to 11 weeks) and long (greater than or equal to 12 weeks) episodes of bacteriuria which expressed type 1 fimbriae as assayed by mannose-sensitive hemagglutination were 59, 65, and 92%, respectively. Isolates with the pil operon (the genome for type 1 fimbriae) from episodes lasting greater than 1 week expressed mannose-sensitive hemagglutination more frequently (P = 0.011) than pil-positive isolates from episodes of less than or equal to 1 week. Isolates from episodes of greater than 1 week also bound significantly more Tamm-Horsfall protein than isolates from episodes of less than or equal to 1 week (P = 0.044). Although nearly half of the isolates produced P fimbriae, an important virulence factor for the development of pyelonephritis, no correlation with persistence could be made. Overall, the E. coli isolates expressed traits similar to those of strains that caused cystitis. Type 1 fimbriae appear to be important for the persistence of E. coli in the long-term-catheterized urinary tract.

Aged↗

The use of proxy responses for aged patients in long-term care settings.

To evaluate the utility of proxy responses for aged residing in a long-term care institution, 106 non-severely cognitively impaired institutionalized patients and their designated proxies were interviewed using an identical interview schedule (53 pairs of patient-proxy interviews). Questions on selected diseases, symptoms and demographic characteristics were included and agreement between respondents and proxies was evaluated. Proxies attempted to provide information on most questions. For many medical diseases and demographic characteristics, proxies provided information which agreed with that provided by patients. However, proxies had more difficulty providing comparable answers about symptoms. It is concluded that a proxy's knowledge of a patient varies by topic. While proxy reports of specific diseases are consistent with the patient's responses, proxy reports of subjective items such as symptoms are not. Recommendations for future research in this area and the importance of these conclusions for other researchers relying on proxy reports are discussed.

Aged↗

Catheter-associated urinary tract infections.

The two most common indications for long-term catheterization are recalcitrant urinary incontinence and urinary obstruction that is not corrected by surgery. For incontinent patients, if behavioral changes, nursing care, special clothes, special bed clothes, and medications have not been successful, then a device to collect urine must be considered. For men such a device is a condom catheter; for women an analogous external collection device would be very useful. Suprapubic catheterization may offer an alternative but has been inadequately studied in this patient population. Long-term urinary catheterization has salutary effects for selected patients including patient comfort, family satisfaction, and nursing efficiency and effectiveness. To the patient for whom any physical movement is uncomfortable or painful, and indwelling catheter may be preferable to frequent changes of clothes. Similarly, the family of of severely impaired patients may want to accept the risks of urethral catheterization in order to keep the patient dry. Further, to the extent that the indwelling catheter is effective in decubitus ulcer prevention and/or management, long-term catheterization may diminish the risk of bacteremia or death from soft tissue infection. These benefits of long-term urethral catheterization, in addition to its risks, should be examined in future studies. Once a urethral catheter is in place, even with good catheter hygiene, bacterial entry can be postponed only temporarily; eventually all patients become bacteriuric. Indeed, as the catheter remains in place, organisms continue to enter, others leave or die, and the bacteriuria becomes complex, polymicrobial, and dynamic. Some organisms, particularly recognized uropathogens such as E. coli and K. pneumoniae, appear to reside in the urinary tract itself. Others, such as P. mirabilis, P. stuartii, and M. morganii, probably establish a niche within the urinary catheter, thus increasing their ability to cause subsequent bladder bacteriuria. The complications of long-term urinary catheterization include fevers, acute pyelonephritis, and bacteremias (such as seen in short-term catheterized patients), as well as catheter obstructions, urinary stones, chronic renal inflammation, local periurinary infections, vasicoureteral reflux, renal failure, and, for very long-term catheterized patients, bladder cancer. The thrust of catheter care for the long-term catheterized patient is to prevent complications of the omnipresent bacteriuria. Unfortunately, clinical opportunities for preventing complications are limited.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗

Identification of best electrocardiographic leads for diagnosing anterior and inferior myocardial infarction by statistical analysis of body surface potential maps.

In view of the increasing interest in quantifying and modifying the size of myocardial infarction (MI), it is important to look for clinically practical subsets of electrocardiographic leads that allow the earliest and most accurate diagnosis of the presence and electrocardiographic type of MI. A practical approach is described, taking advantage of the increased information content of body surface potential maps over standard electrocardiographic techniques for facilitating clinical use of body surface potential maps for such a purpose. Multivariate analysis was performed on 120-lead electrocardiographic data, simultaneously recorded in 236 normal subjects, 114 patients with anterior MI and 144 patients with inferior MI, using as features instantaneous voltages on time-normalized QRS and ST-T waveforms. Leads and features for optimal separation of normal subjects from, respectively, anterior MI and inferior MI patients were selected. Features measured on leads originating from the upper left precordial area, lower midthoracic region and the back correctly identified 97% of anterior MI patients, with a specificity of 95%; in patients with inferior MI, features obtained from leads located in the lower left back, left leg, right subclavicular area, upper dorsal region and lower right chest correctly classified 94% of the group, with specificity kept at 95%. Most features were measured in early and mid-QRS, although very potent discriminators were found in the late portion of the T wave.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗

Informed consent by proxy. An issue in research with elderly patients.

The need for clinical study of patients in nursing homes is growing as this population grows; yet many of these patients are mentally incompetent to give informed consent for such research, and the decision must therefore be left to family members or other proxies. We studied the decisions by the proxies for 168 patients in nursing homes about whether to permit the patients' participation in a study involving minimal risk. The proxies were family members in all but one case, and 78 of 168 (46 percent) refused consent. Refusal was significantly associated (P less than 0.001) with the views that research should not be done in nursing homes, that the study would disturb the patient, that the patient, if able, would refuse to participate in the study, and that the proxy would refuse to participate in such a study if asked. Of the 55 proxies who believed that the patient would refuse consent, however, 17 (31 percent) gave consent, in apparent opposition to the patient's wishes. We conclude that refusal by family members to allow incompetent elderly patients to participate in studies may be an important obstacle to research among the elderly. Both the selection of proxies and the bases for their decisions require further study and definition.

Aged↗

Adherence to uroepithelial cells of Providencia stuartii isolated from the catheterized urinary tract.

The long-term catheterized urinary tract appears to offer a niche for Providencia stuartii, otherwise an unusual clinical isolate. P. stuartii, the most frequent and persistent isolate from the urine of 51 long-term catheterized patients, was recovered from 761 of 1230 (62%) weekly urine specimens. To test the hypothesis that prevalence of this species may be due to adherence properties of the organism, 20 selected strains from 14 patients at two nursing homes, representing six distinct serotypes and harbouring combinations of nine different plasmid species, were tested for adherence to uroepithelial cells (UEC). Optimal conditions were determined for differentiating strains on the basis of in vitro adherence to UEC. These strains, grown in nutrient broth, were incubated with UEC isolated from the urine of a healthy adult female (10(8) bacteria per 10(5) cells). Washed UEC, retained on 8 micron pore diameter filters, were transferred to slides, fixed and stained; bacteria were counted on each of 40 cells. Fourteen of the 20 strains were defined as adherent to UEC by comparison of mean adherent bacteria and percentage of uroepithelial cells with more than 10 bacteria. Adherence was compared to that of a P-fimbriated strain of Escherichia coli. It was not inhibited by 50 mM-mannose. We conclude that the majority of P. stuartii isolates are adherent to UEC in vitro and suggest that this may play a role in the persistence of this organism in the catheterized urinary tract.

Bacterial Adhesion↗

Double-blind, prospective, multicenter trial comparing ceftazidime with moxalactam in the treatment of serious gram-negative infections.

Ceftazidime is a new antimicrobial agent possessing excellent in vitro activity against most members of the family Enterobacteriaceae and against Pseudomonas aeruginosa. We conducted a double-blind, prospective, multicenter trial to compare ceftazidime with moxalactam in the treatment of serious gram-negative infections. The overall favorable response rates for the two regimens were similar (93 of 106 [88%] and 84 of 97 [86%], respectively). Among these, the response rates of the 56 gram-negative bacteremias and the 23 P. aeruginosa infections were comparable. Both groups had similar incidences of subsequent infections with P. aeruginosa, enterococci, and yeasts. A total of 13% of the patients in the moxalactam group developed a prolonged prothrombin time (P less than 0.01), and three patients demonstrated clinical bleeding. These results suggest that although the overall efficacy of both regimens was similar, treatment with moxalactam resulted in a higher incidence of prolongation of prothrombin time with an attendant risk of bleeding. In nonneutropenic patients, ceftazidime as a single agent is safe and effective in gram-negative bacillary infections.

Adult↗