Associations among antimicrobial use and antimicrobial resistance of Salmonella spp. isolates from 60 Alberta finishing swine farms

The study objectives were to identify potential associations between reported antimicrobial use (AMU) practices and antimicrobial resistance (AMR) of fecal and environmental Salmonella spp. isolates (n = 322 isolates) recovered from 60 Alberta finishing swine farms, and to estimate the amount of pen and farm level variation in AMR. The AMU data were collected through a questionnaire. Separate multilevel logistic regression models were built for six antimicrobials with prevalence of resistance >or=5% using the Generalized Linear Latent and Mixed Model (GLLAMM) procedure. In-feed use of tylosin in finishers was associated with increased odds of resistance in Salmonella isolates to ampicillin (OR = 61.56), streptomycin (OR = 11.70), and multiple antimicrobials (OR = 4.90). Injectable penicillin use in growers was associated with decreased odds of resistance in Salmonella isolates to streptomycin (OR = 0.06), kanamycin (OR = 0.03), and multiple antimicrobials (OR = 0.12). Injectable penicillin use in finishers was associated with decreased odds of resistance in Salmonella isolates to ampicillin (OR = 0.007) and chloramphenicol (OR = 0.04). Overall, these results indicate that AMU in pig production is inconsistently associated with AMR in Salmonella from finishing swine. Variation in AMR prevalence of Salmonella isolates of swine was moderate to high at pen and farm levels for most antimicrobials suggesting that interventions at the pen and farm levels might be beneficial in reducing the emergence of AMR Salmonella in swine populations.

Antimicrobial resistance of fecal Escherichia coli isolated from grow-finish pigs in 20 herds in Alberta and Saskatchewan

Escherichia coli (n = 1439), isolated from the feces of apparently healthy grow-finish pigs in 20 herds in Alberta and Saskatchewan, were tested for susceptibility to 16 antimicrobials. All isolates were susceptible to amikacin, ceftriaxone, and ciprofloxacin and less than 1% was resistant to amoxicillin-clavulanic acid, cefoxitin, ceftiofur, gentamicin, and nalidixic acid. Resistance was most common to tetracycline (66.8%), sulfamethoxazole (46.0%) and streptomycin (33.4%). Twenty-one percent of the isolates were susceptible to all drugs, while 57% were resistant to 2 or more antimicrobials. Unconditional associations between resistances provided insight into the potential for co-selection. Every resistance-outcome was associated with at least 2 other drug-resistances. These associations illustrate the propensity for resistance phenotypes to occur together and the importance of considering co-selection in antimicrobial use decisions. A 2nd analysis explored the associations between resistance phenotypes in E. coli and Salmonella spp. from the same herd. Only 2 resistances in Salmonella were associated with herd-level E. coli resistance, indicating that E. coli is a poor sentinel for Salmonella AMR within herds. Herd-level management, including antimicrobial use, could affect antimicrobial resistance. The intra-class correlation between isolates within herds ranged from 0.1 to 0.46, which confirmed resistance clustered within herds. This suggests herd-level interventions might mitigate antimicrobial resistance. Overall, these results reflect the on-farm selection pressure for resistance and the potential food-safety risk from near-market animals. These data provide a baseline for comparisons with future on-farm monitoring of antimicrobial resistance in E. coli.

Prevalence of antimicrobial resistance in fecal generic Escherichia coil isolated in western Canadian cow-calf herds. Part I--beef calves

The objective of this study was to describe antimicrobial resistance patterns in fecal generic Escherichia coli obtained from calves in western Canadian cow-calf herds. Susceptibility testing was completed on 1677 isolates obtained from 480 beef calves in 91 herds in the spring, and from 1187 isolates obtained from 394 calves in 45 herds in the fall of 2002. Resistance was rare to antimicrobials classified as being of very high importance to human health. Isolates were most commonly resistant to tetracycline, sulphamethoxazole, and streptomycin. Resistance to at least one antimicrobial was identified in 48.8% of the isolates collected in the spring, and 7.0% of those collected in the fall. Spring or fall calf resistance status was not associated with calf gender, breed, age of the dam, or if the calf was treated before sample collection. Calves < or = 3 days of age were less likely to be resistance positive than calves > 10 days of age.

Comparison of antimicrobial resistance in generic Escherichia coil and Salmonella spp. cultured from identical fecal samples in finishing swine

The objectives of this study were to investigate the associations between antimicrobial resistance patterns in generic Escherichia coli and Salmonella spp. isolates recovered from identical pen pooled fecal samples, and to evaluate potential clustering of multiple isolates of these organisms within identical fecal samples. Up to 5 generic E. coli (n = 922 isolates) and Salmonella spp. (n = 922 isolates) isolates were obtained from each of 188 pen pooled fecal samples that had been collected from 45 finishing swine farms in Alberta in 2000, and tested for susceptibility to 15 antimicrobials. No isolates of either organism were resistant to 3rd generation cephalosporins or fluoroquinolones, which in Canada are considered antimicrobials of very high importance to human health. Approximately twice as many generic E. coli isolates as Salmonella spp. isolates were resistant to at least 1 antimicrobial. In addition, E. coli isolates showed more multidrug-resistance patterns. No significant association was observed between the resistance phenotypes of Salmonella spp. and E. coli at the fecal sample level. More clustering at the sample level was observed for proportions of antimicrobial resistance (AMR) in Salmonella spp. isolates than E. coli indicating that in future studies it might be sufficient to test fewer than 5 Salmonella spp. isolates per sample.

Prevalence of antimicrobial resistance in fecal generic Escherichia coil isolated in western Canadian beef herds. Part II--cows and cow-calf pairs

The objective of this study was to describe antimicrobial resistance in fecal generic Escherichia coli isolated from cows and cow-calf pairs from western Canadian beef herds. Susceptibility testing was completed on 1555 E. coli isolates (n = 533 cows from 69 herds) harvested from fresh fecal samples in the spring of 2002, and 630 isolates (n = 105 cow-calf pairs from 10 herds) collected in the spring of 2003. Only 1 cow isolate was resistant to an antimicrobial classified by Health Canada as being of very high importance to human medicine. Resistance to at least 2 antimicrobials was detected in 7.1% of the 2002 cow isolates, in 3.4% of the 2003 cow isolates, and 23.2% of the 2003 calf isolates. In the cows, resistance to at least 1 antimicrobial was not associated with cow breed (P = 0.16), cow age (P = 0.14), or previous cow treatment (P = 0.56). In the calves, resistance to at least 1 antimicrobial was not predicted by whether or not its dam was resistant to at least 1 antimicrobial (P = 0.36).

Antimicrobial resistance of fecal Salmonella spp. isolated from all phases of pig production in 20 herds in Alberta and Saskatchewan

Salmonella spp. (n = 468), isolated from the feces of sows, nursery, and grow-finish pigs in 20 farrow-to-finish herds in Alberta and Saskatchewan, were tested for susceptibility to 16 antimicrobials. No resistance was identified to amikacin, amoxicillin-clavulanic acid, ceftiofur, ceftriaxone, ciprofloxacin or nalidixic acid, and less than 1% of the isolates were resistant to cefoxitin and gentamicin. Isolates were most commonly resistant to tetracycline (35%) and sulfamethoxazole (27%). Overall, 59% of the Salmonella were susceptible to all 16 drugs (pansusceptible). Isolates from sows were more likely to be pansusceptible than isolates from nursery or grow-finish pigs. Resistance to 2 or more drugs occurred in 29% of the isolates and was significantly more likely to occur in Salmonella from nursery pigs than from sows. The odds of resistance to 4 of the drugs, streptomycin, ampicillin, kanamycin and cephalothin, were significantly higher in isolates from nursery pigs than grow-finish pigs, while the odds of resistance to 2 drugs, tetracycline and streptomycin, were higher in Salmonella from nursery pigs than from sows. More age-specific risk factor studies are needed to investigate these differences between production phases.

Antimicrobial resistance in generic Escherichia coli isolated from swine fecal samples in 90 Alberta finishing farms

The objective of this study was to determine the prevalence of antimicrobial resistance in generic Escherichia coli isolates obtained from 90 Alberta finisher swine farms. Up to 5 isolates were obtained from each of 269 pooled fecal samples and were classified as susceptible or resistant according to Clinical and Laboratory Standards Institute guidelines. Of the 1322 isolates, 166 (12.6%) were susceptible to all 15 antimicrobials. No resistance to amikacin, ceftiofur, ceftriaxone, or ciprofloxacin, antimicrobials of importance in human medicine, was observed. Relatively low frequencies of resistance were observed to gentamicin (1.1%), amoxicillin/clavulanic acid (0.7%), and cefoxitin (0.7%). Higher frequencies of resistance were observed for tetracycline (78.9%), sulfisoxazole (49.9%), streptomycin (49.6%), ampicillin (30.6%), chloramphenicol (17.6%), kanamycin (10%), and trimethoprim/ sulfamethoxazole (6.4%). Among the isolates resistant to > or = 2 antimicrobial classes, 20.8%, 20.6%, 18.2%, 7.0%, 1.8%, 0.2%, and 0.2% were resistant to 2, 3, 4, 5, 6, 7, and 8 antimicrobials, respectively. The most common multidrug-resistance patterns (resistance to > or = 2 antimicrobial classes) were streptomycin-tetracycline (9.4%), streptomycin-sulfisoxazole-tetracycline (6.2%), and ampicillin-streptomycin-sulfisoxazole-tetracycline (6.1%). More clustering (higher intra-class correlation coefficients) in antimicrobial resistance was observed for isolates at the same visit than for isolates from different visits in the same farm, indicating that sampling more farms, testing fewer isolates per visits, and taking longer periods between visits may be appropriate and more efficient for a better understanding of potential shifts in resistance over time.

Farm-level risk factors for the presence of Salmonella in 89 Alberta swine-finishing barns

This study investigated potential risk factors for the presence of Salmonella on 89 Alberta swine-finishing farms with the use of a questionnaire. Salmonella status was regressed on each fixed effect in a logistic mixed regression model, with farm as the random effect. Eleven variables were significant at the 10% level: farm type, number of square feet per pen, number of pigs per pen, source of feed, ration type, dust control measures, cat presence, reported effective mouse-control measures, time required to be away from pigs before visiting the farm, precautions taken when entering or leaving the farm, and reported use of antimicrobials through water. Three factors remained significant at the 5% level in the multivariable analysis: farm type, ration type, and precautions taken when entering or leaving the farm. Finishing barns at multisite operations or individual grow-to-finish farms had a greater risk of the presence of Salmonella at a single visit than did finishing barns at farrow-to-finish farms. The use of pelleted and wet feed was associated with higher odds of the presence of Salmonella than was the use of meal feed. Farms that required their personnel or visitors to shower before entering and before leaving had increased odds of the presence of Salmonella compared with farms that provided boots and coveralls; no significant difference was observed between the latter category and farms that used boot disinfection. Further work is necessary to better understand the effectiveness of all-in/all-out pig management and disinfection practices in reducing the presence of Salmonella in swine and to evaluate the association with certain types of feed.

A real-time PCR assay for the detection of Salmonella in a wide variety of food and food-animal matricest

Conventional culture methods have traditionally been considered the "gold standards" for the isolation and identification of foodborne pathogens. However, culture methods are labor-intensive and time-consuming. We have developed a real-time PCR assay for the detection of Salmonella in a variety of food and food-animal matrices. The real-time PCR assay incorporates both primers and hybridization probes based on the sequence of the Salmonella invA gene and uses fluorescent resonance energy transfer technology to ensure highly sensitive and specific results. This method correctly classified 51 laboratory isolates of Salmonella and 28 non-Salmonella strains. The method was also validated with a large number of field samples that consisted of porcine feces and cecal contents, pork carcasses, bovine feces and beef carcasses, poultry cecal contents and carcasses, equine feces, animal feeds, and various food products. The samples (3388) were preenriched in buffered peptone water and then selectively enriched in tetrathionate and Rappaport-Vassiliadis broths. Aliquots of the selective enrichment broths were combined for DNA extraction and analysis by the real-time PCR assay. When compared with the culture method, the diagnostic sensitivity of the PCR assay for the various matrices ranged from 97.1 to 100.0%, and the diagnostic specificity ranged from 91.3 to 100.0%. Kappa values ranged from 0.87 to 1.00, indicating excellent agreement of the real-time PCR assay to the culture method. The reduction in time and labor makes this highly sensitive and specific real-time PCR assay an excellent alternative to conventional culture methods for surveillance and research studies to improve food safety.

Longitudinal study of Salmonella species in 90 Alberta swine finishing farms

The aim of this study was to determine the farm prevalence of Salmonella in 90 Alberta finishing swine farms over a 5-month period, to evaluate Salmonella distribution in the farm environment and to describe Salmonella serovar diversity on these farms. Ten veterinary practitioners selected 90 Alberta swine farms based on an annual production of > or =2000 market pigs per farm and the willingness of the producers to participate in the study. Between May and September 2000, twenty samples were collected from finishing swine and the environment of each farm. The annual production of selected farms represented approximately 25% of the market swine production in Alberta. Participating farms were geographically representative of major swine production areas in Alberta. Sixty (66.7%) farms had at least one Salmonella-positive sample, with confidence interval (CI) of 57.1-77.2%. Salmonella were detected in 14.3% of fecal and 20.1% of environmental samples. The number of Salmonella-positive samples per farm ranged from 1 to 19. Among environmental samples, Salmonella were most frequently recovered from boots (38.6%) and the main drain (31.8%). Twenty-two serovars were detected on the 60 Salmonella-positive farms. Serovars Typhimurium (78 isolates), Derby (71 isolates) and Infantis (47 isolates) were the most common. A single serovar was detected on 58 farms, while 2, 3 and >3 serovars were detected on 15, 10 and 7 farms, respectively. The Salmonella farm status changed frequently over the 5-month period indicating the dynamic nature of Salmonella infections on these farms.

Antimicrobial resistance of isolated from finishing swine and the environment of 60 Alberta swine farms

The study objective was to describe and evaluate antimicrobial resistance profiles in Salmonella isolated from Alberta swine finishing farms. Salmonella isolates (n = 322) were obtained from 192 fecal and 84 environmental samples of the 60 Salmonella-positive swine finishing farms. Isolates were classified susceptible, intermediate or resistant based on NCCLS guidelines. More than half of the isolates (53.4%) were susceptible to all of the 18 antimicrobials in the testing panel. No resistance was observed to amikacin, amoxicillin/clavulanic acid, cefoxitin, ceftiofur, ceftriaxone, cephalothin, ciprofloxacin, imipenem or nalidixic acid. Less than 1% of isolates were resistant to apramycin, gentamicin and trimethoprim/sulfamethoxazole. Higher frequencies of resistance were observed for chloramphenicol (4.7%), ampicillin (7.8%), kanamycin (11.8%), sulfamethoxazole (21.1%), streptomycin (25.5%) and tetracycline (38.8%). Eleven Salmonella serovars had isolates with resistance to > or =3 antimicrobials. The most frequently resistant serovar was Salmonella Derby, with 27 (38.0%) isolates resistant to > or =3 antimicrobials, including resistance to five and six antimicrobials. An absence of resistance to cephalosporins and fluoroquniolones and a low proportion of isolates resistant to amikacin, amoxicillin/clavulanic acid, apramycin, gentamicin and trimethoprim/sulfamethoxazole are encouraging findings from public health and animal health perspectives. Frequent resistance observed for ampicillin, kanamycin, sulfamethoxazole, streptomycin and tetracycline, antimicrobials commonly used in veterinary medicine for decades, indicates an urgent need to utilize these antimicrobials more prudently if their benefits are to be preserved.

Glucocorticoid feedback sensitivity and adrenocortical responsiveness in posttraumatic stress disorder

BACKGROUND

Decreased basal cortisol levels have been reported in individuals with posttraumatic stress disorder (PTSD). There is evidence for enhanced negative feedback sensitivity of the hypothalamic-pituitary-adrenal (HPA) axis in PTSD, which could account for this, but other possible mechanisms have not been ruled out. We examined the HPA axis employing a metyrapone-cortisol infusion protocol designed to study negative feedback sensitivity.

METHODS

Vietnam combat trauma-exposed subjects met DSM-IV criteria for PTSD. Exclusion criteria included substance abuse and most medications. Endogenous feedback inhibition was removed by blocking cortisol synthesis with oral metyrapone and reintroduced by intravenous infusion of cortisol. In a placebo condition, subjects received oral placebo and normal saline infusion. Serial blood samples drawn over 4 hours were assayed for adrenocorticotrophic hormone (ACTH), cortisol, and 11-deoxycortisol. Selected samples were assayed for cortisol binding globulin (CBG) and dehydroepiandrosterone (DHEA).

RESULTS

Basal plasma cortisol was significantly decreased in PTSD subjects (n = 13) compared with control subjects (n = 16). No significant difference in the ACTH response to cortisol infusion following metyrapone was observed; however 11-deoxycortisol was significantly decreased in PTSD subjects. In addition, CBG was significantly increased in PTSD subjects, and DHEA was significantly decreased in both PTSD and combat-exposed control subjects.

CONCLUSIONS

These observations suggest decreased adrenocortical responsiveness may be an additional or alternative mechanism accounting for low cortisol in PTSD.

Trauma, symptoms of posttraumatic stress disorder, and associated problems among incarcerated veterans

OBJECTIVE

To help improve treatment for incarcerated veterans, the study examined exposure to trauma, symptoms of posttraumatic stress disorder (PTSD), functional status, and treatment history in a group of incarcerated veterans.

METHODS

A convenience sample of 129 jailed veterans who agreed to receive outreach contact completed the Life Event History Questionnaire, the PTSD Checklist-Civilian Version (PCL-C), and the Addiction Severity Index. Participants who had scores of 50 or above on the PCL-C, designated as screening positive for PTSD, were compared with those whose scores were below 50, designated as screening negative for PTSD.

RESULTS

Some 112 veterans (87 percent) reported traumatic experiences. A total of 51 veterans (39 percent) screened positive for PTSD, and 78 veterans (60 percent) screened negative. Compared with veterans who screened negative for PTSD, those who screened positive reported a greater variety of traumas; more serious current legal problems; a higher lifetime use of alcohol, cocaine, and heroin; higher recent expenditures on drugs; more psychiatric symptoms; and worse general health despite more previous psychiatric and medical treatment as well as treatment for substance abuse.

CONCLUSIONS

The findings encourage the development of an improved treatment model to keep jailed veterans with PTSD from repeated incarceration.

Multidimensional assessment of anger in Vietnam veterans with posttraumatic stress disorder

This study examined the effects of combat exposure and posttraumatic stress disorder (PTSD) on dimensions of anger in Vietnam veterans. Vietnam combat veterans were compared with Vietnam era veterans without war zone duty on the Multidimensional Anger Inventory (MAI). Combat veterans were not significantly more angry than their veteran peers who did not serve in Southeast Asia. Additionally, various parameters of war zone duty were not highly associated with anger scores. However, combat veterans with PTSD scored significantly higher than veterans without PTSD on measures of anger arousal, range of anger-eliciting situations, hostile attitudinal outlook, and tendency to hold anger in. These results suggest that PTSD, rather than war zone duty, is associated with various dimensions of angry affect.

Behavioral and neuroendocrine responses to sodium lactate infusion in subjects with posttraumatic stress disorder

OBJECTIVE

Sodium lactate infusion has induced flashbacks accompanied by panic attacks in male combat veterans with posttraumatic stress disorder (PTSD) and concurrent panic disorder. This study addressed whether sodium lactate induces flashbacks or other intrusive PTSD symptoms in PTSD patients free of concurrent panic disorder.

METHOD

Behavioral, cardiovascular, catecholamine, and cortisol responses to infusion of 0.5 M sodium lactate were compared among seven subjects with PTSD without panic disorder, seven subjects with panic disorder only, and seven healthy subjects.

RESULTS

Six of the seven PTSD subjects but no panic disorder or healthy subjects reported flashbacks or other intrusive PTSD symptoms during lactate infusion. Flashbacks were accompanied by substantial anxiety symptoms. Cortisol levels were low in the PTSD subjects.

CONCLUSIONS

Sodium lactate induces flashbacks in persons with PTSD without comorbid panic disorder. The relationship between anxiety responses accompanying a PTSD flashback and those in a panic attack remains unclear.

Plasma norepinephrine kinetics in patients with posttraumatic stress disorder

To determine whether basal sympathetic nervous system (SNS) function is increased in patients with posttraumatic stress disorder (PTSD), we used a radioisotope dilution technique to assess basal arterialized plasma norepinephrine (NE) kinetics in 12 men who were Viet Nam combat veterans with PTSD and six normal controls. In addition to determining the rates of appearance of NE into, and clearance of NE from, plasma, we measured basal arterialized plasma levels of epinephrine (EPI), and also vital signs, in both groups. Patients with PTSD actually manifested lower arterialized plasma levels of NE, and had lower rates of appearance of NE into plasma, than did controls. The rate of NE clearance from plasma was unaltered in PTSD patients. Patients with PTSD also showed a trend toward lower arterialized EPI levels than controls, but manifested a trend toward higher diastolic blood pressure. Our data indicate that basal SNS activity is not increased in patients with PTSD and that previous reports of increased resting SNS activity in this population may instead reflect SNS reactivity.

Posttraumatic stress disorder symptoms and precombat sexual and physical abuse in Desert Storm veterans

The purpose of this research was to study the association between precombat sexual and physical abuse and combat-related posttraumatic stress disorder (PTSD) symptoms in a clinical sample of male and female Desert Storm veterans. Two hundred ninety-seven veterans provided data on precombat sexual and physical abuse, precombat psychiatric problems, sociodemographics, Desert Storm combat exposure, and PTSD symptomatology using the Mississippi Scale. Men reported significantly higher levels of combat exposure, and women described significantly more frequent precombat abuse. Precombat-abused veterans reported more frequent precombat psychiatric histories. Analysis of covariance revealed that gender significantly modified the impact of precombat abuse on combat-related and other PTSD symptomatology after adjusting for precombat psychiatric history and level of combat exposure. Specifically, females describing precombat abuse reported much greater PTSD symptomatology than did females denying precombat abuse. These results in conjunction with previous research suggest that a relationship between precombat abuse and combat-related PTSD may exist. Prospective, longitudinal studies of both men and women are needed.

Combat-related posttraumatic stress disorder and severity of substance abuse in Vietnam veterans

This study examined the effects of Vietnam war-zone duty and combat-related posttraumatic stress disorder (PTSD) on severity of drug- and alcohol-abuse disorders among veterans seeking treatment for substance dependence. Combat-exposed Vietnam-theater veterans (N = 108) were compared with Vietnam-era veterans without war-zone duty (N = 151) on psychometric measures of drug and alcohol abuse. There were no differences between theater and era veterans on these measures. However, Vietnam-theater veterans with PTSD experienced more severe drug- and alcohol-abuse problems than did theater veterans without PTSD and were at greater risk for having both forms of substance abuse. Further analyses showed that PTSD was significantly related to some dimensions of drug- and alcohol-abuse problems but not to other dimensions. These findings indicate that PTSD, rather than combat stress per se, is linked to severity of substance abuse. Finally, reexperiencing and avoidance/numbing components of PTSD were more strongly associated with drug abuse than alcohol abuse, but physiological arousal symptoms of PTSD were more highly correlated with alcohol abuse.

Basal sympathoadrenal function in posttraumatic distress disorder

Research has consistently shown that patients with posttraumatic stress disorder (PTSD) manifest greater changes in heart rate, blood pressure, and plasma epinephrine than controls when exposed to trauma-related laboratory stressors. However, findings are equivocal as to whether PTSD subjects differ from controls on basal, or tonic, measures of autonomic activity. In this study, PTSD patients (n = 11) and asymptomatic controls (n = 11) were compared on measures of basal sympathoadrenal function, including plasma norepinephrine and epinephrine as well as heart rate and blood pressure. Results showed that PTSD patients were not significantly different from control subjects on any measure. Although phasic alterations in autonomic function in PTSD have been consistently found in previous research, this study suggests that tonic sympathetic nervous system activity in PTSD patients may not differ from that of healthy controls.

Frequency of symptoms and concurrent psychiatric disorder in Vietnam veterans with chronic PTSD

The frequency of symptoms of posttraumatic stress disorder within each of three categories--reexperiencing, avoidance or numbing, and physiological arousal--was examined in 116 Vietnam combat veterans with a diagnosis of PTSD. The prevalence of all PTSD symptoms was greater than 50 percent except for flashbacks, psychogenic amnesia, and sense of foreshortened future. Comorbidity in a subgroup of 48 patients was assessed using operational criteria for DSM-III-R mental disorders. Mood disorders, psychoactive substance abuse disorders, and other anxiety disorders frequently co-occurred with PTSD, but psychotic disorders were uncommon. These findings provide empirical validation of the DSM-III-R diagnostic criteria for PTSD.

Autonomic responses to stress in Vietnam combat veterans with posttraumatic stress disorder

This study tested the hypothesis that combat veterans with posttraumatic stress disorder (PTSD) experience sympathetic nervous system activation in response to war-related laboratory stimuli. Circulating plasma catecholamines, vital signs, and affect ratings were measured in 10 Vietnam combat veterans with PTSD and 11 control subjects, during and after viewing combat and noncombat stress films. PTSD subjects responded more strongly than controls to the combat film, with greater increases in plasma epinephrine, pulse, blood pressure, and subjective distress. The increases in autonomic activity of PTSD subjects was more pronounced and long lasting in response to the combat film than to the noncombat film, but type of film had no systematic effect on control subjects' responses. These findings are consistent with biological models that posit sympathoadrenal activation in response to memory-evoking cues of traumatic events in PTSD.

Convergent validity of measures of PTSD in Vietnam combat veterans

The authors evaluated the convergent validity of several widely used psychometric tests of posttraumatic stress disorder (PTSD) symptoms against DSM-III-R criteria for PTSD in 130 Vietnam combat veterans. Significant positive correlations were found between these instruments and the number of DSM-III-R symptoms endorsed, supporting the validity of psychometric instruments as continuous measures of PTSD symptom severity. The various psychometric measures also correlated moderately with one another, suggesting that they assess related but somewhat separate PTSD phenomena. Finally, predicted relationships between stressors and symptoms were supported by significant correlations between degree of traumatic combat exposure and DSM-III-R and psychometric indexes of PTSD.

Differences between psychotic and nonpsychotic patients on content dimensions of the MMPI Sc scale

This study examined elevated MMPI Sc scores among psychotic and nonpsychotic patients to determine whether homogeneous item-content dimensions could clarify the precise meaning of elevations on scale Sc. A total of 45 psychotic patients were compared with 56 nonpsychotic psychiatric patients on the Harris and Lingoes subscales of the Sc scale. All subjects had T-score elevations on scale Sc greater than or equal to 70. The two criterion groups did not differ on overall scale Sc scores, but a distinctive pattern of subscale scores emerged that discriminated the samples. Psychotic patients obtained significantly higher scores on subscales measuring bizarre thinking and perceived loss of control over impulses and emotions. Conversely, nonpsychotics endorsed significantly more items on subscales concerned with symptoms of depression, anxiety, and thinking difficulties. These data suggest that homogeneous item-content dimensions of the Sc scale provide a means for distinguishing between psychotic and nonpsychotic patients who otherwise appear similar on overall scale Sc.

Application of a social skills training program in the modification of interpersonal deficits among retarded adults: a clinical replication

Six mentally retarded adults, equally divided into two treatment groups, were provided with individualized social skills training programs. Treatment, evaluated via a multiple-baseline design strategy, was sequentially and cumulatively applied across target behaviors over a four-week intervention period. Behavioral observation probes and social validation measures served as the primary dependent variables. Results indicated that (a) treatment was effective for virtually all behaviors across all subjects, (b) improvements occurred for both training and generalization scenes, and (c) behavioral performance was maintained one month following the termination of treatment.