Traumatic Hip Dislocation: Pediatric and Adult Evaluation and Management

Traumatic hip dislocation of a native hip joint represents an orthopaedic emergency that should be treated promptly. Dislocations can be classified based on the associated injuries and the direction of dislocation. Expeditious evaluation, reduction, and management of associated injuries are required to optimize short and long-term function of the hip. There are several important differences between the blood supply and ossification of the pediatric hip that necessitate different strategies for the evaluation and management of traumatic hip dislocations in pediatric patients. Appropriate treatment is dictated by the direction and type of dislocation as well as associated injuries. In addition to closed reduction, arthroscopy, open reduction (potentially with fracture fixation and/or soft-tissue repair), osteotomy, and total hip arthroplasty all have roles in treatment. Consensus on optimal postreduction activity protocols after simple hip dislocation remain unestablished. Short and long-term outcomes are largely driven by the amount of time from injury to reduction and associated injuries.

Langerhans Cell Histiocytosis in the Pediatric Spine Requiring Stabilization: A Literature Review and Report of 3 Cases

CASE

This report describes 3 cases of Langerhans cell histiocytosis (LCH) of the cervical and thoracic spine in patients aged 4 to 10 years. Each patient had painful lytic spinal lesions with vertebral body collapse and posterior involvement suggesting instability requiring corpectomy, grafting, and fusion. All 3 patients were doing well at their most recent follow-up without pain or recurrence.

CONCLUSION

Although LCH of the pediatric spine is usually successfully treated non-operatively, we recommend corpectomy and fusion when there is instability of the spinal column and/or severe stenosis. Posterior element involvement occurred in all 3 cases and may lead to instability.

Effect of Race and Geography on Patient- and Parent-Reported Quality of Life for Children With Congenital Upper Limb Differences

PURPOSE

Patient beliefs about health and disability are shaped by many social factors and are a key determinant in their ultimate outcome. We hypothesized that pediatric and parent-reported outcome measures regarding a child's congenital upper limb difference will be affected by geographic location, parent education, sex, ethnicity, race, age, and presence of additional medical comorbidities.

METHODS

Patients enrolled in the multicenter Congenital Upper Limb Difference registry were included. Age, sex, race, ethnicity, medical comorbidities, highest level of parental education, area deprivation index, and geographic region were recorded. Patient-Reported Outcomes Measurement Information System (PROMIS) in the pediatric and parent-reported domains of upper extremity, anxiety, pain interference, peer relationships, and depressive symptoms were collected.

RESULTS

The only difference between geographic regions in the United States in pediatric and parent-reported PROMIS was that parents in the Midwest reported higher upper extremity function scores in children with upper limb differences than the West. Black patients demonstrated higher scores in parent and child-reported domains of depression, pain, and anxiety, and lower scores in upper extremity function than White and Asian peers. Additionally, children with medical comorbidities also demonstrated worse outcomes in multiple PROMIS domains. There was no difference in scores based on sex, parent education, and ethnicity.

CONCLUSIONS

In children with congenital upper limb differences, race and additional medical comorbidities have an impact on patient- and parent-reported PROMIS outcome measures in multiple domains, with Black children and those with additional medical comorbidities scoring lower than their peers.

CLINICAL RELEVANCE

As we strive to develop a health care system that provides equitable care to all patients, providers who care for children with upper limb differences should be aware that race and additional medical comorbidities can negatively affect patient- and parent-reported PROMIS outcome measures.

Can the Femoro-Epiphyseal Acetabular Roof (FEAR) Index Be Used to Distinguish Dysplasia from Impingement?

BACKGROUND

Classifying hips with structural deformity on the spectrum from impingement to dysplasia is often subjective and frequently inexact. Currently used radiographic measures may inaccurately predict a hip's morphological stability in borderline hips. A recently described radiographic measure, the Femoro-Epiphyseal Acetabular Roof (FEAR) index, has demonstrated an ability to predict stability in the borderline hip. This measure is attractive to clinicians because procedures can be used on the basis of a hip's pathomechanics. This study was designed to further validate and characterize the FEAR index in a skeletally immature population, in hips with dysplasia/femoroacetabular impingement (FAI), and in asymptomatic hips.

QUESTIONS/PURPOSES

(1) What are the characteristics of the FEAR index in children and how does the index change with skeletal maturation? (2) How does the FEAR index correlate with clinical diagnosis and surgical treatment in a large cohort of symptomatic hips and asymptomatic controls? (3) How does the FEAR index correlate with clinical diagnosis in the borderline hip (lateral center-edge angle [LCEA] 20°-25°) group?

METHODS

A total of 220 participants with symptomatic investigational hips with a clinical diagnosis of dysplasia or FAI between January 2008 and January 2018 were retrospectively collected from the senior author's practice. Investigational hips were excluded if they had any femoral head abnormalities preventing LCEA measurement (for example, Perthes disease), Tönnis osteoarthritis grade greater than 1, prior hip surgery, or prior femoral osteotomy. In the 220 participants, 395 hips met inclusion criteria. Once exclusion criteria were applied, 15 hips were excluded due to prior hip surgery or prior femoral osteotomy, and 12 hips were excluded due to femoral head deformity. A single hip was then randomly selected from each participant, resulting in 206 investigational hips with a mean age of 13 ± 3 years. Between January 2017 and December 2017, 70 asymptomatic control participants were retrospectively collected from the senior author's institutional trauma database. Control hips were included if the AP pelvis film had the coccyx centered over the pubic symphysis and within 1 to 3 cm of the superior aspect of the symphysis. Control hips were excluded if there was any fracture to the pelvis or ipsilateral femur or the participant had prior hip/pelvis surgery. After exclusion criteria were applied, 16 hips were excluded due to fracture. One hip was then randomly selected from each participant, resulting in 65 control hips with a mean age of 16 ± 8 years. Standardized standing AP pelvis radiographs were used to measure the FEAR index, LCEA, and Tönnis angle in the investigational cohort. Standardized false-profile radiographs were used to measure the anterior center-edge angle (ACEA) in the investigational cohort. Two blinded investigators measured the FEAR index with an intraclass correlation coefficient of 0.92 [95% CI 0.84 to 0.96]. Question 1 was answered by comparing the above radiographic measures in age subgroups (childhood: younger than 10 years; adolescence: 10 to 14 years old; maturity: older than 14 years) of dysplastic, FAI, and control hips. Question 2 was answered by comparing the radiographic measures in all dysplastic, FAI, control hips, and a subgroup of operatively or nonoperatively managed dysplasia and FAI hips. Question 3 was answered by comparing the radiographic measures in borderline (LCEA 20°-25°) dysplastic, FAI, and control hips.

RESULTS

The FEAR index was lower in older dysplastic of hips (younger than 10 years, 6° ± 9°; 10 to 14 years, 4° ± 10°; older than 14 years, 5° ± 9°; p < 0.001) and control hips (younger than 10 years, -6° ± 5°; 10 to 14 years, -15° ± 4°; older than 14 years, -16° ± 7°; p < 0.001). The diagnosis and age groups were independently correlated with the FEAR index (p < 0.001). The relationship between the FEAR index and diagnosis remained consistent in each age group (p = 0.11). The FEAR index was higher in all dysplastic hips (mean 5° ± 10°) than in asymptomatic controls (mean -13° ± 7°; p < 0.001) and FAI hips (mean -10° ± 11°; p < 0.001). Using -1.3° as a cutoff for FAI/control hips and dysplastic hips, 81% (112 of 139) of hips with values below this threshold were FAI/control, and 89% (117 of 132) of hips with values above -1.3° were dysplastic. The receiver operator characteristics area under the curve (ROC-AUC) was 0.91. Similarly, the FEAR index was higher in borderline dysplastic hips than in both asymptomatic borderline controls (p < 0.001) and borderline FAI hips (p < 0.001). Eighty-nine percent (33 of 37) of hips with values below this threshold were FAI/control, and 90% (37 of 41) of hips with values above -1.3° were dysplastic. The ROC-AUC for borderline hips was 0.86.

CONCLUSION

The FEAR index was associated with the diagnosis of hip dysplasia and FAI in a patient cohort with a wide age range and with varying degrees of acetabular deformity. Specifically, a FEAR index greater than -1.3° is associated with a dysplastic hip and a FEAR index less than -1.3° is associated with a hip displaying FAI. Using this reliable, developmentally based radiographic measure may help hip preservation surgeons establish a correct diagnosis and more appropriately guide treatment.

LEVEL OF EVIDENCE LEVEL

III, diagnostic study.

Characterization of doxycycline-loaded calcium phosphate cement: implications for treatment of aneurysmal bone cysts

Percutaneous doxycycline for treatment for aneurysmal bone cysts (ABCs) has been shown to decrease recurrence rates, however, this requires multiple procedures, includes the risks soft tissue necrosis, and does not provide structural support. We propose utilizing curettage with doxycycline-loaded calcium phosphate cement. This study aimed to evaluate the elution profile of doxycycline from calcium phosphate cement. Calcium phosphate cement underwent an in vitro elution protocol evaluating doxycycline concentrations of 0, 5, 10, and 15 mg/mL. Eluted concentrations were quantified utilizing high performance liquid chromatography at predetermined time points over 96 h. Compressive strength was evaluated both pre- and post-elution and micro-computed tomography was utilized to assess changes in cement porosity. Cement with 15 mg/mL of doxycycline maintained a higher average concentration (mean, 95% confidence intervals) (14.5 µg/mL [9.2-19.9 µg/mL]) compared to both 5 mg/mL (5.8 µg/mL [3.1-8.6 µg/mL]; P < 0.001) and 10 mg/mL (8.4 ± µg/mL [6.0-10.9 µg/mL]; P < 0.001). Ultimate stress significantly decreased between pre- and post-elution samples for 10 mg/mL (P= 0.001) and 15 mg/mL (P = 0.004) groups. This study demonstrated a dose-dependent response in ultimate strength and compressive modulus with addition of doxycycline to calcium phosphate cement.

A Comparison of the Outcomes for Cartilage Defects of the Knee Treated With Biologic Resurfacing Versus Focal Metallic Implants

PURPOSE

To compare the results of focal metallic resurfacing with biologic procedures in patients more than 35 years of age with isolated, full thickness defects of the femoral condyle.

METHODS

A total of 61 patients met the selection criteria resulting in 30 patients treated with biological procedures, including debridement, microfracture, osteochondral autograft transplantation, osteochondral allograft, and autologous chondrocyte implantation (BIO group), and 32 patients treated with focal metallic resurfacing (CAP group). The BIO and CAP groups were matched according to treatment location, defect grade and size, and age profile. Outcomes included Western Ontario and McMaster Osteoarthritis Index (WOMAC), Short Form-12, and satisfaction. The primary combination endpoint was determined as a 20% improvement (minimum clinically important difference-20) on WOMAC pain and function at 2 years and no additional index lesion-related surgical intervention. Safety and effectiveness were also reported.

RESULTS

Thirty patients in the BIO group (mean age of 44.6, range 35-64) had an average follow-up of 2.6 years and 32 patients in the CAP group (mean age 47.9, range 37-68) were followed for 2.0 years. Fifty-three percent in the BIO group and 75% in the CAP group achieved success per the endpoint definition. The mean total WOMAC score improved significantly for both groups (BIO: 57-78; P < .001) (CAP: 41-86; P < .001). The physical component score (Short Form-12 PCS) improved significantly in the CAP group only (30-36.4; P < .001). Good to excellent patient satisfaction was achieved by 80% in BIO and 91% in CAP. There were 4 secondary procedures on the index lesion in the BIO group and 2 in the CAP group.

CONCLUSIONS

Careful patient selection can achieve high satisfaction rates with both biological and focal metal resurfacing procedures for the treatment of isolated focal chondral lesions of the femoral condyle in the knee. Focal metallic resurfacing results in similar clinical outcomes and provides excellent success rates at short-term follow-up.

LEVEL OF EVIDENCE

Level III comparative study.

Cationic aluminum hydride complexes: reactions of carbene–alane adducts with trityl-borate

Reaction of (Idipp)AlH₃ with [Ph₃C][B(C₆F₅)₄] in toluene affords the dimeric aluminum dication [((Idipp)AlH(μ-H))₂][B(C₆F₅)₄]₂ with the corresponding reaction of (IBn)AlH₃ gives [(IBn)₂AlH][B(C₆F₅)₄]₂.

Prevention of HPV-related oral cancer: assessing dentists' readiness

OBJECTIVES

Epidemiological research indicates an association between the Human Papillomavirus (HPV) with a subset of oral cancers (OC). Dentists may play a role in primary prevention of HPV-related OC by discussing the HPV vaccine with patients. This study assessed dentists' readiness to discuss the HPV vaccine with female patients.

STUDY DESIGN

Cross-sectional web-based survey.

METHODS

A web-based survey based on the Transtheoretical Model was administered among Florida dentists (n = 210).

RESULTS

The majority of participants (97%) fell into the precontemplation and contemplation stages of readiness to discuss the HPV vaccine with patients. Perceived role and liability were determined to be predictive of dentists in contemplation stage as opposed to those in precontemplation (P < 0.05).

CONCLUSIONS

Findings suggest liability and perceived role as processes of change necessary to guide dentists to primary prevention of HPV-related OC despite high levels of knowledge. As public awareness of HPV-related OC increases, dentists may become more involved in primary prevention. Results of the current study may assist in developing intervention strategies for engaging dentists in discussing the HPV vaccine with patients.

Delay in presentation to primary care physicians is the main reason why patients with rheumatoid arthritis are seen late by rheumatologists

OBJECTIVES

To study the delay from the time of symptom onset to assessment by a Rheumatologist in patients with rheumatoid arthritis (RA) and to determine the contributions of patient and physician dependent factors to this delay.

METHODS

Data were collected from 169 consecutive patients with RA at the time of assessment by Rheumatologists working in hospitals serving an inner city population in Birmingham, UK. Dates were recorded for: (i) onset of inflammatory joint symptoms; (ii) initial assessment in primary care; and (iii) referral from primary to secondary care. (iv) initial assessment by a rheumatologist in secondary care.

RESULTS

The median delay from the onset of symptoms to a patient being assessed in secondary care was 23 weeks (IQR 12-54 weeks). The median delay before the patient was assessed in primary care was 12 weeks (IQR 4-28 weeks). For 96 patients (57%) more than half of the overall delay in assessment in secondary care was accounted for by a delay in assessment in primary care.

CONCLUSIONS

Patient dependent factors, leading to a delay in consulting primary care physicians, are the principal reasons for the delay in patients with RA being seen by Rheumatologists in our population. A considerable body of evidence demonstrates that the earlier that therapy is introduced the better the clinical outcome. Consequently it is important to understand why some patients with RA delay in seeking medical advice, in order to allow effective interventions to reduce this delay.

Chlorimipramine: A novel anticancer agent with a mitochondrial target

Mitochondria have been suggested to be a potential intracellular target for cancer chemotherapy. In this report, we demonstrate the ability of the tricyclic antidepressant chlorimipramine to kill human glioma cells in vitro by a molecular mechanism resulting in an increase in caspase 3 activity following inhibition of glioma oxygen consumption. Studies with isolated rat mitochondria showed that chlorimipramine specifically inhibited mitochondrial complex III activity, which causes decreased mitochondrial membrane potential as well as mitochondrial swelling and vacuolation. The use of chlorimipramine in human as an effective, non-toxic cancer therapeutic having a strong selectivity between cancer cells and normal cells on the basis of their mitochondrial function is discussed.

Region-specific corpus callosum atrophy correlates with the regional pattern of cortical glucose metabolism in Alzheimer disease

BACKGROUND

Positron emission tomographic studies of patients with Alzheimer disease (AD) suggest a loss of metabolic functional interactions between different cortical regions. Atrophy of the corpus callosum as the major tract of intracortical connective fibers may reflect decreased cortical functional integration in AD.

OBJECTIVES

To investigate whether regional atrophy of the corpus callosum is correlated with regional reductions of cortical glucose metabolism, as shown by positron emission tomography, and whether primary white matter degeneration is a possible cofactor of corpus callosum atrophy in AD.

PATIENTS AND METHODS

We measured total and regional cross-sectional areas of the corpus callosum on midsagittal magnetic resonance imaging scans from 12 patients with AD and 15 age-matched control subjects. Regional cerebral metabolic rates for glucose in cortical lobes were measured by positron emission tomography using fludeoxyglucose F 18. White matter hyperintensities were rated in T2-weighted magnetic resonance imaging scans.

RESULTS

The total cross-sectional area of corpus callosum was significantly reduced in patients with AD, with the most prominent changes in the rostrum and splenium and relative sparing of the body of the corpus callosum. Frontal and parietal lobe metabolism was correlated with the truncal area of the corpus callosum in AD. The ratios of frontal to parietal and of frontal to occipital metabolism were correlated with the ratio of anterior to posterior corpus callosum area in the group with AD. White matter hyperintensities did not correlate with corpus callosum atrophy in the patients with AD.

CONCLUSION

The regional pattern of corpus callosum atrophy correlated with reduced regional glucose metabolism independently of primary white matter degeneration in the patients with AD.

Dissociation between corpus callosum atrophy and white matter pathology in Alzheimer's disease

OBJECTIVE

To determine whether the size of the corpus callosum is related to the extent of white matter pathology in patients with AD and age-matched healthy control subjects.

METHODS

White matter hyperintensity load and corpus callosum size were compared between 20 clinically diagnosed AD patients and 21 age-matched healthy control subjects. We investigated the effect of age and disease severity on corpus callosum size and white matter hyperintensity, in addition to the relation between corpus callosum areas and white matter hyperintensity load.

RESULTS

We found significant regional atrophy of the corpus callosum in AD when compared with control subjects, although the groups did not differ in their white matter hyperintensity load. We further showed a region-specific correlation between corpus callosum size and white matter hyperintensity in the control group but not in AD patients. In the AD group, corpus callosum size correlated with age and dementia severity, whereas white matter hyperintensity correlated only with age.

CONCLUSION

Corpus callosum atrophy in AD can occur independent of white matter degeneration, likely reflecting specific AD pathology in projecting neurons.

Survival of Listeria spp. on raw whole chickens cooked in microwave ovens

The prevalence of microwave ovens in North American homes has increased dramatically within the last decade. Although microwave ovens are primarily used for reheating of foods, they are now more commonly being applied to the cooking of raw foods. Although cooking of raw foods, according to manufacturers' instructions targets an organoleptically acceptable end product, the process does not address the microbiological safety of the cooked food. Seventeen microwave ovens from various commercial suppliers were used to cook naturally contaminated whole raw broilers (< or = 1.8 kg) and roasters (> 1.8 kg) according to manufacturers' instructions. Temperature probes (six per chicken) were used to measure the temperature of chickens immediately after cooking and during the holding period. Of 81 Listeria-positive raw broilers and 93 raw roasters, 1 (1.2%) and 9 (9.7%), respectively, yielded viable Listeria spp. after microwave cooking. Of these, two were undercooked (visual inspection), one was over the maximum weight stipulated by the oven manufacturer and another one was over the maximum weight and undercooked. A significantly greater proportion of contaminated cooked birds was observed with roasters than with broilers, where for one of these contaminated roasters, the temperature at all six measured sites was > or = 87 degrees C. Most of the postcook Listeria-positive birds were associated with 2 of the 17 microwave ovens. Factors such as wattage, cavity size, and the presence or absence of a turntable seemingly did not play a significant role in the survival of Listeria spp. in microwave-cooked chicken. However, the general inability of microwave ovens to uniformly heat chicken carcasses was noted. In order to promote greater safety of microwave-cooked foods, general recommendations for consumers are provided.

Fate of Listeria monocytogenes on Modified-Atmosphere Packaged Turkey Roll Slices

The growth of Listeria monocytogenes on turkey roll slices stored at 4 and 10°C under a variety of different modified-atmospheres (Ms) was examined. While increasing in numbers on turkey roll slices stored in air, or in environments containing CO₂ levels of 30 or 50% (remainder N₂), L. monocytogenes was inhibited by a MAs containing 70% CO₂, 30% N₂. In all cases, Listeria did not grow as well in any of the MAs as compared to air. In addition, for all MAs tested, pseudomonads were inhibited to an equal or greater extent than L. monocytogenes . It is recommended that any MA-packaged turkey sandwiches with a shelf-life approaching 30 days, should be stored in a MA containing at least 70% CO₂ to guard against the potential growth of L. monocytogenes .

Presence and growth of Listeria monocytogenes in naturally-contaminated meats

A total of 101 retail samples of pâté were analysed for the presence of Listeria spp., with 12 and seven samples respectively, found to contain L. innocua and L. monocytogenes, and one each containing L. welshimeri and L. ivanovii. The ability of Listeria spp. to grow on these pâté products was assessed over a 3-week storage period at 4 degrees C. L. monocytogenes was able to survive on the four naturally-contaminated pâtés tested, but growth was only apparent for L. innocua in a turkey-based pâté. Similar findings were noted with growth studies done with L. monocytogenes on naturally-contaminated wieners, ham and turkey breast. Very low numbers (< 10 cfu/g) of the organism were found initially on these products, with L. monocytogenes being found capable of surviving for long periods at 4 degrees C, but being incapable of multiplying. Similarly, pâtés artificially-inoculated with L. monocytogenes showed survival but not growth of the organism over a 3-week storage period at 4 degrees C.

Factors Influencing Survival of Listeria monocytogenes in Milk in a High-Temperature Short-Time Pasteurizer

Heat resistance experiments were carried out with Listeria monocytogenes which had been grown at three different temperatures (30, 39, and 43°C). Heated whole milk was inoculated with L. monocytogenes and then passed through a high-temperature short-time system at 72, 69, 66, and 63°C for a minimum holding time of 16.2 s. Heated cells were recovered both aerobically and anaerobically using four different methods: direct plating, most probable number, cold enrichment, and warm enrichment. Significant differences in recovery of L. monocytogenes were observed depending on the growth temperature. Cells grown at 43, 39, or 30°C, held 1 d at 4°C, and then heated at 69°C showed an overall decrease in numbers of approximately 2.1, 2.8, and 4.1 logs, respectively. Cells grown at 39°C and then held 3 d at 4°C appeared to be the most heat sensitive. Although cells grown at 43 and 39°C were capable of surviving at the minimum high-temperature short-time temperature (72°C), those grown at 30°C were not. In some instances, anaerobic incubation enhanced the recovery of L. monocytogenes , as compared to cells recovered aerobically, although these differences were not statistically significant. While L. monocytogenes can survive minimum pasteurization treatment (71.7°C/16 s) under certain conditions, common methods of handling, processing, and storing fluid milk will provide an adequate margin of safety.

Antibiotic Resistance of Agricultural and Foodborne Salmonella Isolates in Canada: 1986-1989

A total of 689 Salmonella cultures isolated during 1986-1989 from Canadian agricultural products and from imported fish, shellfish, and reptiles were examined for resistance to a test panel of 11 antibiotics. The incidence of antibiotic resistance in strains from all sources seemingly increased during the study period, whereas the occurrence of resistance within individual sample categories fluctuated annually. Although poultry figured as a major reservoir of resistant salmonellae (53.4%), red meats and fish/shellfish also yielded substantial numbers of resistant strains. The range of streptomycin (27.1 to 48.7%) and tetracycline (24.3 to 37.8%) resistance among poultry and red meat isolates, and identification of meat isolates carrying chloramphenicol (0.4 to 9.1%) and ampicillin (3.4 to 11.4%) resistance codons was disquieting. Most of the multiply-resistant (≥ 2 antibiotics) strains belonged to somatic serogroups B and C, with poultry occurring as the principal reservoir of multiresistant phenotypes. Of the 27 resistance patterns encountered in this study, all but two contained a resistance determinant for streptomycin and/or tetracycline. These findings underscore a disturbing level of antibiotic resistant Salmonella in the food chain, and the need to reassess the alleged benefits of subtherapeutically medicated feeds in current animal husbandry practices.

Inadequacy of Small Transfer Volume and Short (6 h) Selective Enrichment for the Detection of Foodborne Salmonella

The propensity of short (6 h) selective enrichment combined with a preenrichment to enrichment transfer volume ratio of 1:100 to provide greater method brevity could not be demonstrated. Inoculation of tetrathionate brilliant green (35 and 43°C), Rappaport-Vassiliadis (43°C), and selenite cystine (35°C) enrichment broths (9.0 ml) with 0.1 ml of preenrichment culture and incubation for 6 h identified, respectively, 107 (84.9%), 104 (82.5%), 112 (88.9%), and 113 (89.7%) of the 126 contaminated samples detected in the present study; homologous results with the 1.0-ml transfer volume showed a marginal increase in sensitivity. Recoveries of foodborne salmonellae with the standard (24-h) period of selective enrichment were generally transfer volume-independent and consistently exceeded that obtained with 6-h enrichment cultures. Results further underlined the importance of enrichment at an elevated (43°C) temperature for the effective repression of competitive microflora, and the facilitated isolation of Salmonella on plating media.

Feeding trials of Listeria monocytogenes with a nonhuman primate model

One of the major unanswered questions regarding the presence of Listeria monocytogenes in foods is how many cells must be ingested in order to cause illness. To answer this question, studies were undertaken by using Macaca fascicularis (cynomolgus monkey) as an animal model. Healthy nonhuman primates were dosed with various concentrations of L. monocytogenes suspended in sterile whole milk. Final concentrations of 10(5), 10(7), and 10(9) total cells of the organism were used; a control was also included. Blood samples, as well as fecal and nasal specimens, were taken at various time intervals. Only animals that received 10(9) cells of L. monocytogenes became noticeably ill, with symptoms of septicemia, irritability, loss of appetite, and occasional diarrhea. Monkeys that received 10(7) and 10(9) cells shed L. monocytogenes in the feces for approximately 21 days. In monkeys that received the dose of 10(9) cells, severe lymphopenia and neutrophilia occurred within 48 h. In a separate trial, monkeys received Maalox to reduce the gastric acidity of the stomach. However, no substantial differences were observed between Maalox-treated and control monkeys.

Performance of the Microplate BacTrace™ ELISA Technique for Detection of Foodborne Salmonella

The developmental BacTrace^™ ELISA system which recognizes a common structural antigen (CSA-1) in the cell wall of target microorganisms was tested with pure cultures and naturally contaminated foods. The system readily detected all of the 104 Salmonella test strains but produced 38 (52.1%) false-positive reactions upon examination of 73 nonsalmonellae cultures. Citrobacter freundii , Escherichia coli , and Proteus mirabilis were primarily responsible for erroneous results. Of 119 foods tested, 37 (31.1%) were found to contain Salmonella by a standard cultural procedure. Parallel BacTrace™ testing of the nutrient broth (NB), tetrathionate brilliant green (TBG₄₃), and selenite cystine (SC₃₅) broth cultures arising from standard cultural analyses identified 24 (64.9%), 25 (67.6%), and 31 (83.8%) Salmonella contaminated foods, respectively. Maximum sensitivity of the test system (89.2%) could be attained through combination of ELISA results from both TBG₄₃ and SC₃₅. False-positive reactions were particularly prominent with high moisture foods.

Pet turtles: a continuing international threat to public health

The occurrence of Salmonella spp. in red-eared (Pseudemys scripta elegans) turtle eggs imported into Canada from Louisiana in June to September 1988 was examined. Of 28 lots tested, six (21%) lots from three of four exporters harbored salmonellae. Salmonella poona and Salmonella arizonae were frequently encountered in both fertile eggs and packaging moss. Turtles hatched in our laboratory from affected lots of eggs shed Salmonella in tank water for up to 11 months. Widespread use of gentamicin on turtle farms to produce Salmonella-free eggs for export apparently encouraged development of antibiotic resistance in bacterial strains. Of 37 Salmonella strains isolated in this study, 30 (81%) were gentamicin resistant. Such high levels of antibiotic-resistant salmonellae in turtle eggs pose a serious human health risk. Further marketing of turtle eggs and hatchlings should be curtailed until consistent production and distribution of Salmonella-free stocks can be assured.