Potential importance of Legionella species as etiologies in community acquired pneumonia (CAP).

Large percentages of patients with community acquired pneumonia (CAP) do not have a defined etiology. Between 1992-1993, 99 acute and convalescent sera were collected from patients with CAP of unknown etiology. The sera were tested using an indirect immunofluorescence antibody assay (IFA) against the following antigens: Legionella pneumophila, serogroups 3,5,6 and 7 and L. longbeachae, L. anisa, L. bozemanii and Legionella-Like Amoebal Pathogens (LLAP). A four-fold rise in titer to at least one of the antigens tested, was seen in 14% of patients; 8% to L. bozemanii, 4% to L. anisa, 2% to S. lyticum, 2% to LLAP 10 and 1% each to LLAP 1, 6 and 9. Two patients reacted to several antigens. These results indicate that other species of legionella may be important in the etiology of CAP. L. bozemanii was the organism identified in the majority of these infections. Better diagnostic studies i.e. cultures, serologies and urinary antigen testing, which recognize legionella isolates other than L. pneumophila serogroup 1 need to be developed.

Incidence of community-acquired pneumonia requiring hospitalization. Results of a population-based active surveillance Study in Ohio. The Community-Based Pneumonia Incidence Study Group.

BACKGROUND: Pneumonia is the leading cause of death due to infectious diseases in the United States; however, the incidence of most infections causing community-acquired pneumonia in adults is not well defined. METHODS: We evaluated all adults, residing in 2 counties in Ohio, who were hospitalized in 1991 because of community-acquired pneumonia. Information about risk factors, symptoms, and outcome was collected through interview and medical chart review. Serum samples were collected from consenting individuals during the acute and convalescent phases, and specific etiologic diagnoses were assigned based on results of bacteriologic and immunologic tests. RESULTS: The incidence of community-acquired pneumonia requiring hospitalization in the study counties in 1991 was 266.8 per 100,000 population; the overall case-fatality rate was 8.8%. Pneumonia incidence was higher among blacks than whites (337.7/100,000 vs 253.9/ 100,000; P < .001), was higher among males than females (291.4 vs 244.8; P < .001), and increased with age (91.6/100,000 for persons aged < 45 years, 277.2/ 100,000 for persons aged 45-64 years, and 1012.3/ 100,000 for persons aged > or = 65 years; P < .001). Extrapolation from study incidence data showed the projected annual number of cases of community-acquired pneumonia requiring hospitalization in the United States to be 485,000. These data provide previously unavailable estimates of the annual number of cases that are due to Legionella species (8000-18,000), Mycoplasma pneumoniae (18,700-108,000), and Chlamydia pneumoniae (5890-49,700). CONCLUSIONS: These data provide information about the importance of community-acquired pneumonia and the relative and overall impact of specific causes of pneumonia. The study provides a basis for choosing optimal empiric pneumonia therapy, and allows interventions for prevention of pneumonia to be targeted at groups at greatest risk for serious illness and death.

Susceptibility of ninety-eight clinical isolates of Legionella to macrolides and quinolones using the Etest.

Isolates of Legionella from 98 patients with Legionnaires' disease hospitalized in Columbus, Ohio, USA between 1991 through 1995 were tested for antimicrobial susceptibility to macrolides and quinolones using the Etest. Most (87%) isolates were Legionella pneumophila serogroup 1. All isolates tested remain susceptible to erythromycin, azithromycin, clarithromycin, ciprofloxacin, ofloxacin, and levofloxacin. In vitro susceptibility testing of Legionella to representative macrolides and quinolones should be considered to detect the emergence of resistant isolates.

Stability of Legionella urinary antigens over time.

Twenty-two urine samples positive for Legionella pneumophila serogroup 1 antigen by EQUATE radioimmunoassay (RIA) (Binax, Portland, ME, USA) were stored at various temperatures and the RIA repeated at 1, 7, 30, 90, and 120 days to evaluate stability of the urinary antigens. The mean ratios of patient/negative control remained stable. Although there was a 10% decrease in the mean ratios after 1 month, changes were not significant. However, individual samples with ratios close to 3 may fall to < 3.

Injuries due to firearms in three cities.

BACKGROUND: To describe the incidence and outcome of injuries due to firearms, we conducted a population-based study of fatal and nonfatal gunshot wounds in three cities: Memphis, Tennessee; Seattle; and Galveston, Texas. METHODS: Records of the police, medical examiners, ambulance crews, and hospital emergency departments and hospital admissions were monitored to identify all injuries caused by firearms that were severe enough to prompt emergency medical treatment. These records were linked to generate a complete picture of each event. Census data were used to calculate rates of injury for various population groups. RESULTS: A total of 1915 cases of injury due to firearms were identified between November 16, 1992, and May 15, 1994. The crude rate of firearm injury per 100,000 person-years was 222.6 in Memphis, 143.6 in Galveston, and 54.1 in Seattle. Approximately 88 percent of the injuries were incurred during confirmed or probable assaults; 7 percent were sustained in the course of suicide or attempted suicide; unintentional injuries accounted for 4 percent of the cases. Handguns were used in 88 percent of the cases in which the type of weapon was recorded. Five percent of the 1677 victims who were brought to a hospital emergency department could not be resuscitated; 53 percent were hospitalized, and 42 percent were treated and released. Ninety-seven percent of the deaths occurred within 24 hours of the injury. Emergency department and inpatient charges exceeded $16.5 million. CONCLUSIONS: Injuries due to firearms, most involving handguns, are a major cause of morbidity and mortality in U.S. urban areas. The incidence varies greatly from city to city.

Nosocomial and community-acquired Staphylococcus aureus bacteremias from 1980 to 1993: impact of intravascular devices and methicillin resistance.

The rate of nosocomial bacteremia due to Staphylococcus aureus has increased over the past decade, but trends in community-acquired S. aureus bacteremia are less certain. This hospital-based observational study compares nosocomial and community-acquired S. aureus bacteremias during 1980-1983 and 1990-1993. The rate of nosocomial S. aureus bacteremia increased from 0.75 to 2.80 cases per 1,000 discharges, while the rate of community-acquired S. aureus bacteremia increased from 0.84 to 2.43 cases per 1,000 discharges. The number of nosocomial device-related bacteremias increased eightfold; 56% of S. aureus bacteremias were associated with devices during 1990-1993. Intravascular devices were associated with no community-acquired S. aureus bacteremias during 1980-1983 but with 22% during 1990-1993. Methicillin-resistant S. aureus (MRSA) seldom caused bacteremia during 1980-1983. From 1990 to 1993, MRSA caused 32% and 18.5% of nosocomial and community-acquired S. aureus bacteremias, respectively. The rates of both community-acquired and nosocomial S. aureus bacteremias have increased significantly since 1980. In addition to their role in nosocomial infections, MRSA and intravascular device-related S. aureus bacteremias are emerging problems in the nonhospital setting.

Risk factors for domestic acquisition of legionnaires disease. Ohio legionnaires Disease Group.

BACKGROUND: Legionnaires disease is a common cause of adult pneumonia. Outbreaks of legionnaires disease have been well described, but little is known about sporadically occurring legionnaires disease, which accounts for most infections. Exposure to contaminated residential water sources is I plausible means of disease acquisition. METHODS: Employing a matched case-control study design in 15 hospitals in 2 Ohio counties, we prospectively enrolled 146 adults diagnosed as having nonepidemic, community-acquired legionnaires disease and compared each with 2 hospital-based control patients, matched for age, sex, and underlying illness category. An interview regarding potential exposures was followed by a home survey that included sampling residential sources for Legionella. Interview and home survey data were analyzed to estimate the risk of acquiring legionnaires disease associated with various exposures. RESULTS: Multivariate analysis showed that a nonmunicipal water supply (odds ratio [OR], 2.26; 95% confidence interval [CI], 1.17-4.37), recent residential plumbing repair (OR, 2.39; 95% CI, 1.10-5.18), and smoking (OR, 3.48; 95% CI, 2.09-5.79) were independent risk factors for legionnaires disease. Univariate analysis suggested that electric (vs gas) water heaters (OR, 1.97; 95% CI, 1.10-3.52), working more than 40 hours weekly (OR, 2.13; 95% CI, 1.12-4.07), and spending nights away from home before illness (OR, 1.68; 95% CI, 1.03-2.74) were additional possible risk factors. Lower chlorine concentrations in potable water and lower water heater temperatures were associated with residential Legionella colonization. CONCLUSIONS: A proportion of sporadic cases of legionnaires disease may be residentially acquired and are associated with domestic potable water and disruptions in residential plumbing systems. Potential strategies to reduce legionnaires disease risk include consistent chlorination of potable water, increasing water heater temperatures, and limiting exposure to aerosols after domestic plumbing repairs.

Comparison of Binax Legionella Urinary Antigen EIA kit with Binax RIA Urinary Antigen kit for detection of Legionella pneumophila serogroup 1 antigen.

The Legionella Urinary Antigen EIA kit (Binax, Portland, Maine) was compared with the EQUATE RIA Legionella Urinary Antigen kit (Binax) for its ability to detect the presence of urinary antigens to Legionella pneumophila serogroup 1. Urine specimens from patients without Legionnaires' disease (n = 33) were negative by both methods (specificity, 100%). Twenty (77%) of 26 urine specimens from patients with Legionnaires' disease positive by the radioimmunoassay kit were also positive by the enzyme immunoassay (EIA) kit. If the cutoff for a positive EIA result were lowered to a ration of > or = 2.5, 23 of 26 (88%) urine specimens would have been positive by EIA and the specificity would remain 100%. Use of the EIA kit is an acceptable method for detecting L. pneumophila serogroup 1 urinary antigens by laboratories that do not want to handle radioactive materials.

Three-rescuer CPR: the method of choice for firefighter CPR?

STUDY OBJECTIVE: To compare the quality of CPR provided by firefighters performing three-rescuer CPR with that achieved by firefighters trained to provide standard two-rescuer CPR. DESIGN: Eight months after training a large number of firefighters to perform three-rescuer CPR, we used a quasi-experimental design to compare the performance of a randomly selected subset of these companies to that achieved by a control group of engine companies that received refresher training in standard two-rescuer CPR. Both groups used bag-valve masks to provide rescue ventilations. Testing was conducted on a no-notice basis with a recording mannequin. Key actions were scored by an experienced observer using explicit pass-fail criteria. Mannequin-generated strip charts were used to calculate the rate and depth of chest compressions and the ventilatory rate, volume, and minute ventilation in a blinded manner. SETTING: Fire stations of the Memphis Fire Department. The department is the sole provider of first-responder emergency care to the citizens of Memphis, Tennessee (population, 610,000). RESULTS: Three-rescuer teams delivered a mean minute ventilation substantially greater than that produced by two-rescuer teams (7.7 +/- 5.3 L versus 4.9 +/- 4.2 L, P < .001). Intergroup differences in the mean depth of chest compressions were less marked, but they were still significant (17.2 +/- 8.3 mm of recorder-needle deflection versus 13.7 +/- 7.0 mm, P < .001). CONCLUSION: Three rescuers can produce better CPR than two when a bag-valve-mask device is used. The technique is easily learned and readily retained.

Reevaluation of the definition of Legionnaires' disease: use of the urinary antigen assay. Community Based Pneumonia Incidence Study Group.

Cases of Legionnaires' disease have been categorized as definitive and presumptive. The sensitivity and specificity of antibody titers of > or = 256 and of urinary antigen ratios of > or = 3 were evaluated in 68 patients with "definitive" Legionnaires' disease and in 636 patients with pneumonia who had negative cultures and did not have fourfold rises in titers of antibody to Legionella pneumophila. An acute-phase antibody titer of > or = 256 did not discriminate between cases and noncases (10% vs. 6%; P = .29). The urinary antigen assay gave a positive result in fewer than 1% of noncases but was positive in 55.9% of all cases. This assay was most sensitive (80%) in cases in which L. pneumophila serogroup 1 was isolated. We propose that the case definition for definitive Legionnaires' disease be expanded to include positive urinary antigen assays and that the category of presumptive Legionnaires' disease--based on acute-phase or standing antibody titers of > or = 256 in the nonoutbreak setting--be discarded. The urinary antigen assay will be a valuable tool in the prompt diagnosis of Legionnaires' disease.

The in vitro and in vivo pharmacologic activity of the potent and selective leukotriene B4 receptor antagonist CP-105696.

CP-105696, (+)-1-(3S,4R)-[3-(4-phenyl-benzyl)-4-hydroxy-chroman-7-yl] cyclopentane carboxylic acid, is a structurally novel, selective and potent leukotriene B4 (LTB4) receptor antagonist. In vitro, CP-105696 inhibited [3H]LTB4 (0.3 nM) binding to high-affinity LTB4 receptors on human neutrophils with an IC50 value of 8.42 +/- 0.26 nM. Scatchard analyses of [3H]LTB4 binding to these high-affinity receptors indicated that CP-105696 acted as a noncompetitive antagonist. CP-105696 inhibited human neutrophil chemotaxis mediated by LTB4 (5 nM) in a noncompetitive manner with an IC50 value of 5.0 +/- 2.0 nM. Scatchard analyses of [3H]LTB4 binding to low-affinity receptors on neutrophils indicated that CP-105696 acted as a competitive antagonist at this receptor, and inhibition of LTB4-mediated CD11b upregulation on human neutrophils was competitively inhibited by CP-105696 (pA2 = 8.03 +/- 0.19). CP-105696 at 10 microM did not inhibit either human neutrophil chemotaxis or CD11b upregulation mediated through alternate (i.e., C5a, IL-8, PAF) G-protein coupled chemotactic factor receptors. In isolated human monocytes, LTB4 (5 nM)-mediated Ca++ mobilization was inhibited by CP-105696 with an IC50 value of 940 +/- 70 nM. In vivo, after oral administration, CP-105696 blocked neutrophil and eosinophil infiltration in cavine dermis mediated by either LTB4 or arachidonic acid with ED50 values of 0.3 +/- 0.1 mg/kg. 12(R)-Hydroxyeicosatetraenoic acid-mediated neutrophil infiltration was blocked by 76.4 +/- 14.8% at 3 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Leukotriene B4 plays a critical role in the progression of collagen-induced arthritis.

Leukotriene B4 (LTB4) is a product of the 5-lipoxygenase pathway of arachidonic acid metabolism. LTB4 is a potent chemotactic factor for neutrophils and has been postulated to play an important role in a variety of pathological conditions including rheumatoid arthritis (RA), psoriasis, and inflammatory bowel disease. The role of LTB4 in such diseases has not yet been defined but in this paper we provide direct evidence that LTB4 plays a critical role in a murine model of RA. CP-105,696, (+)-1-(3S,4R)-[3-(4-phenylbenzyl)- 4-hydroxychroman-7-yl]cyclopentane carboxylic acid, is an LTB4 receptor antagonist that inhibits LTB4 binding to human neutrophil membranes with an IC50 of 3.7 nM and inhibits LTB4-induced chemotaxis of these cells with an IC50 of 5.2 nM. CP-105,696 inhibits LTB4-induced neutrophil influx in mouse skin when administered orally with an ED50 of 4.2 mg/kg. CP-105,696 had a dramatic effect on both the clinical symptoms and histological changes of murine collagen-induced arthritis when administered at doses of 0.3-10 mg/kg. Inhibition was not associated with suppression of the humoral immune response to collagen and was equally effective if drug treatment was commenced just prior to the onset of arthritis or throughout the experiment. These results suggest that LTB4 receptor antagonists may be effective therapeutic agents for the treatment of RA.

Do blacks get bystander cardiopulmonary resuscitation as often as whites?

STUDY OBJECTIVE: To determine whether there is an association between the race of a victim of out-of-hospital cardiac arrest and the provision of bystander-initiated CPR. DESIGN: Record review of 1,068 consecutive cases of nontraumatic out-of-hospital cardiac arrest. SETTING: Memphis, Tennessee, a city of more than 600,000 with roughly equal numbers of white and black residents. PARTICIPANTS: Every adult who was seen by municipal emergency medical services personnel for nontraumatic cardiac arrest between March 1, 1989, and June 5, 1992. INTERVENTION: None. RESULTS: Although black and white cardiac arrest victims were similar in many respects, black victims received bystander CPR substantially less frequently than whites (9.8% versus 21.4%; odds ratio, 0.46; 95% confidence interval, 0.34 to 0.61). This difference was slightly more pronounced when the victim collapsed in a public place. In addition to race of the victim, location of the arrest outside the home and having the arrest witnessed were independent determinants of whether a victim was given bystander CPR. Multiple logistic regression analysis showed that the effect of race was independent of the other variables studied. CONCLUSION: Black victims of out-of-hospital cardiac arrest receive bystander CPR less frequently than white victims. Targeted training programs may be needed to improve the rates of bystander CPR among certain groups.

Early discharge after gynaecological surgery.

OBJECTIVE: To determine the safety and acceptability of early discharge after major gynaecological surgery. DESIGN: Retrospective study of patients discharged home on the third day after surgery. Questionnaire to determine patients' attitudes. SETTING: District general hospital with an associated 'Hospital at Home Scheme'. SUBJECTS: 102 women listed for major gynaecological surgery living within the catchment area of the Hospital at Home and considered good surgical risks. MAIN OUTCOME MEASURES: Safety, re-admission rates, nursing time planned and utilised, patients' attitudes. RESULTS: There were no serious complications. Only three patients required re-admission. Less nursing time was required than expected: allocated, 24 h; utilised, less than 10 h for 45%; no night cover for 70.5%. Patient aides performed most of the nursing. There was no excess burden for general practice (45.7% required a home visit). The scheme proved popular with patients. Analgesia and catheter care needed to be improved. CONCLUSION: Discharge on the third postoperative day into an augmented domiciliary care service is safe, popular and cost effective.

Impact of first-responder defibrillation in an urban emergency medical services system.

OBJECTIVE: To evaluate the impact of adding first-responder defibrillation by fire-fighters to an existing advanced life-support emergency medical services system. DESIGN: Nonrandomized, controlled clinical trial with periodic crossover. SETTING: Memphis, Tenn, a city of 610,337 people, which is served by a fire department-based emergency medical services system. All city ambulances provide advanced life support. PATIENTS: Adult victims of out-of-hospital cardiac arrest due to heart disease. INTERVENTION: Twenty of 40 participating engine companies were equipped with an automated external defibrillator and ordered to apply it immediately in all cases of cardiac arrest. The other 20 companies were ordered to start cardiopulmonary resuscitation (CPR) immediately and wait for paramedics to arrive. Every 75 days, group roles were reversed. Care otherwise proceeded according to 1986 American Heart Association guidelines. MAIN OUTCOME MEASURES: Return of spontaneous circulation in the field, survival to hospital admission, survival to hospital discharge, and neurological status at discharge. RESULTS: During the 39-month study interval, 879 patients were treated by a project engine company. Four hundred thirty-one (49%) of these were found in ventricular fibrillation. Bystander CPR was started in only 12% of cases. Overall, firefighters reached the scene a mean of 2.5 minutes faster than simultaneously dispatched paramedics. Although our automated external defibrillators proved to be reliable and efficacious for terminating ventricular fibrillation and pulseless ventricular tachycardia, patients treated by an automated external defibrillator-equipped engine company were no more likely than CPR-treated controls to be resuscitated (32% vs 34%, respectively), to survive to hospital admission (31% vs 29%), or to survive to hospital discharge (14% vs 10%). Neurological outcomes were also similar in the two treatment groups. CONCLUSIONS: In a fast-response, urban emergency medical services system served by paramedics, the impact of adding first-responder defibrillation appears to be small. Early defibrillation alone cannot overcome low community rates of bystander CPR. Careful attention to every link in the "chain of survival" is needed to achieve optimal rates of survival after cardiac arrest.

Gun ownership as a risk factor for homicide in the home.

BACKGROUND: It is unknown whether keeping a firearm in the home confers protection against crime or, instead, increases the risk of violent crime in the home. To study risk factors for homicide in the home, we identified homicides occurring in the homes of victims in three metropolitan counties. METHODS: After each homicide, we obtained data from the police or medical examiner and interviewed a proxy for the victim. The proxies' answers were compared with those of control subjects who were matched to the victims according to neighborhood, sex, race, and age range. Crude and adjusted odds ratios were calculated with matched-pairs methods. RESULTS: During the study period, 1860 homicides occurred in the three counties, 444 of them (23.9 percent) in the home of the victim. After excluding 24 cases for various reasons, we interviewed proxy respondents for 93 percent of the victims. Controls were identified for 99 percent of these, yielding 388 matched pairs. As compared with the controls, the victims more often lived alone or rented their residence. Also, case households more commonly contained an illicit-drug user, a person with prior arrests, or someone who had been hit or hurt in a fight in the home. After controlling for these characteristics, we found that keeping a gun in the home was strongly and independently associated with an increased risk of homicide (adjusted odds ratio, 2.7; 95 percent confidence interval, 1.6 to 4.4). Virtually all of this risk involved homicide by a family member or intimate acquaintance. CONCLUSIONS: The use of illicit drugs and a history of physical fights in the home are important risk factors for homicide in the home. Rather than confer protection, guns kept in the home are associated with an increase in the risk of homicide by a family member or intimate acquaintance.

Predicting the outcome of unsuccessful prehospital advanced cardiac life support.

OBJECTIVE: To determine if failure to achieve return of spontaneous circulation following prehospital advanced cardiac life support (ACLS) warrants termination of efforts at the scene. DESIGN: Retrospective case series. SETTING: Memphis, Tenn, a city of 610337 people that is served by a fire department-based emergency medical service system. All city ambulances provide ACLS. PATIENTS: Adult victims of out-of-hospital cardiac arrest due to heart disease. INTERVENTION: All patients received prehospital ACLS according to the 1986 American Heart Association guidelines. Following prehospital ACLS, all patients were transported to the nearest hospital emergency department whether or not a pulse was restored in the field. MAIN OUTCOME MEASURES: Survival to hospital admission, survival to hospital discharge, and neurological status at discharge. RESULTS: Over the 39-month study interval, the Memphis Fire Department treated 1068 victims of out-of-hospital cardiac arrest. Three hundred ten of these (29%) had return of spontaneous circulation prior to transport for some period. The remaining 758 patients (71%) never regained a pulse and were transported with ongoing cardiopulmonary resuscitation. Patients who had return of spontaneous circulation prior to transport were more likely to be admitted (69% vs 7.0%) and far more likely to be discharged alive (26.5% vs 0.4%) than patients who failed to respond to prehospital ACLS. Three patients who survived to hospital discharge despite failure to achieve return of spontaneous circulation prior to emergency medical service transport sustained their cardiac arrest after paramedic arrival. All three were discharged with moderate to severe cerebral disability. CONCLUSION: Rapid transport of adults who fail to respond to an adequate trial of prehospital ACLS does not result in meaningful rates of survival. In such cases, on-line emergency medical service physicians should authorize paramedics to cease efforts in the field.

Engineering excellence: options to enhance firefighter compliance with standing orders for first-responder defibrillation.

STUDY OBJECTIVE: To assess the quality of care delivered during first-responder defibrillation and to determine the potential efficacy of modifying existing automated external defibrillator designs to improve first-responder performance. DESIGN: Prospective case series. SETTING: An urban emergency medical services system providing first-responder defibrillation and paramedic care. TYPE OF PARTICIPANTS: Firefighters who completed a four-hour (two-session) course in automated external defibrillator operation. METHODS: Heartstart 2000 defibrillators (Laerdal Medical Corp, Armonk, New York) were used in 241 consecutive resuscitation attempts. Written reports and memory module printouts were abstracted to assess firefighter performance of 11 critical actions. The firefighter's response to each opportunity to perform a critical action was scored using explicit pass/fail criteria. RESULTS: Records of 235 automated external defibrillator uses (97.5%) were submitted for analysis. Firefighters shocked within 15 seconds of a "shock indicated" message in 95% of opportunities and reanalyzed the rhythm within 90 seconds of the third consecutive shock (ie, after one minute of CPR) in 80% of cases. However, firefighters reanalyzed the patient's rhythm too soon in 75% of cases, thereby interfering with recommended intervals of CPR. Firefighters failed to reanalyze the patient's rhythm after device-initiated "check patient" prompts 62% of the time. Memory modules were left in the automated external defibrillator during practice sessions in 64 cases, decreasing available memory to monitor automated external defibrillator use in the field. Three instances of failure to withhold CPR during rhythm analysis resulted in a single inappropriate patient shock. No firefighter was shocked inadvertently. CONCLUSION: Current device algorithms result in effective delivery of the initial three shocks. However, firefighters often fail to interpose recommended intervals of CPR between further attempts at defibrillation. Modification of existing device algorithms to provide additional visual and auditory cues may be preferable to relying on the user to recall accurately all the steps in this infrequently performed procedure.