Temporal trends and geographic variations in mortality rates from tobacco and firearms in the United States

We explored temporal trends and geographic variations in United States of America (US) mortality rates from smoking and firearms from 1999 to 2019. To do so, we used the publicly available Centers for Disease Control and Prevention (CDC) Wide Ranging Online Data for Epidemiologic Research (WONDER) with Multiple Cause of Death files from 1999 to 2019. Using age-specific rates and ArcGIS Pro Advanced software for Optimized Hot Spot Analyses from Esri, we generated maps of statistically significant spatial clusters with 90-99% confidence intervals with the Getis-Ord Gi* statistic for mortality from smoking-related causes and firearms. These data show temporal trends and geographic variations in mortality from smoking and firearms in the US. Smoking and firearm-related mortality from assault and suicide increased throughout the US and clustered in the Southeast. Firearm-related suicide also clustered in the continental West and Alaska. These descriptive data generate many hypotheses which are testable in analytic epidemiologic studies designed a priori to do so. The trends suggest smoking and firearm-related causes pose particular challenges to the Southeast and firearms also to the West and Alaska. These data may aid clinicians and public health authorities to implement evidence-based smoking avoidance and cessation programs as well as address firearm mortality, with particular attention to the areas of highest risks. As has been the case with cigarettes, individual behavior changes as well as societal changes are likely to be needed to achieve decreases in premature mortality.

Different biases in meta-analyses of case-control and cohort studies: an example from genomics and precision medicine

PURPOSE

Meta-analyses of observational studies reduce the role of chance but also introduce bias because the individual component studies are not randomized. Further, it is plausible that the bias may be different in case-control and cohort studies. We explored these issues in meta-analyses of observational studies of Opioid Use Disorder (OUD).

METHODS

From a systematic literature review of 152 published meta-analyses, 11 fulfilled the initial inclusion criteria of observational studies of OUD. Of these, 9 were meta-analyses of case-control studies and 2 were meta-analyses of cohort studies but only 4 (3 case-control and 1 cohort) targeted more than one specific chromosomal location.

RESULTS

The meta-analyses of the 3 case-control studies, which included 13 individual studies, identified 12 different single nucleotide polymorphisms on 6 different genes on 5 different chromosomes. None was the same as the gene on Chromosome 15 identified from the meta-analysis of the cohort studies.

CONCLUSIONS

These data, from genetic studies, suggest biases are different in meta-analyses of case-control and cohort studies, perhaps due to greater selection bias in case-control studies. These observations have potential importance in the application of meta-analyses to many common and serious diseases, as well as genomics and precision medicine, including OUD.

Assessment of Probable Opioid Use Disorder Using Electronic Health Record Documentation

IMPORTANCE

Electronic health records are a potentially valuable source of information for identifying patients with opioid use disorder (OUD).

OBJECTIVE

To evaluate whether proxy measures from electronic health record data can be used reliably to identify patients with probable OUD based on Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) (DSM-5) criteria.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cross-sectional study analyzed individuals within the Geisinger health system who were prescribed opioids between December 31, 2000, and May 31, 2017, using a mixed-methods approach. The cohort was identified from 16 253 patients enrolled in a contract-based, Geisinger-specific medication monitoring program (GMMP) for opioid use, including patients who maintained or violated contract terms, as well as a demographically matched control group of 16 253 patients who were prescribed opioids but not enrolled in the GMMP. Substance use diagnoses and psychiatric comorbidities were assessed using automated electronic health record summaries. A manual medical record review procedure using DSM-5 criteria for OUD was completed for a subset of patients. The analysis was conducted beginning from June 5, 2017, until May 29, 2020.

MAIN OUTCOMES AND MEASURES

The primary outcome was the prevalence of OUD as defined by proxy measures for DSM-5 criteria for OUD as well as the prevalence of comorbidities among patients prescribed opioids within an integrated health system.

RESULTS

Among the 16 253 patients enrolled in the GMMP (9309 women [57%]; mean [SD] age, 52 [14] years), OUD diagnoses as defined by diagnostic codes were present at a much lower rate than expected (291 [2%]), indicating the necessity for alternative diagnostic strategies. The DSM-5 criteria for OUD can be assessed using manual medical record review; a manual review of 200 patients in the GMMP and 200 control patients identifed a larger percentage of patients with probable moderate to severe OUD (GMMP, 145 of 200 [73%]; and control, 27 of 200 [14%]) compared with the prevalence of OUD assessed using diagnostic codes.

CONCLUSIONS AND RELEVANCE

These results suggest that patients with OUD may be identified using information available in the electronic health record, even when diagnostic codes do not reflect this diagnosis. Furthermore, the study demonstrates the utility of coding for DSM-5 criteria from medical records to generate a quantitative DSM-5 score that is associated with OUD severity.

Temporal Trends and Geographic Variations in Mortality Rates from Prescription Opioids: Lessons from Florida and West Virginia

OBJECTIVES

To explore temporal trends and geographic variations in mortality from prescription opioids from 1999 to 2016.

METHODS

Centers for Disease Control and Prevention Wide-ranging Online Data for Epidemiologic Research Multiple Cause of Death files were used to calculate age-adjusted rates and 95% confidence intervals (CIs) and create spatial cluster maps.

RESULTS

From 1999 to 2016, counties in West Virginia experienced the highest overall mortality rates in the United States from prescription opioids. Specifically, from 1999 to 2004, the highest rate in West Virginia of 24.87/100,000 (95% CI 17.84-33.73) was the fourth highest in the United States. From 2005 to 2009, West Virginia experienced the highest rate in the United States, 60.72/100,000 (95% CI 47.33-76.71). From 2010 to 2016, West Virginia also experienced the highest rate in the United States, which was 90.24/100,000 (95% CI 73.11-107.36). As such, overall, West Virginia experienced the highest rates in the United States and the largest increases overall of ~3.6-fold between 1999 and 2004 and 2010 and 2016. From 1999 to 2004, Florida had no "hot spots," but from 2006 to 2010 they did appear, and from 2011 to 2016, they disappeared.

CONCLUSIONS

These data show markedly divergent temporal trends and geographic variations in mortality rates from prescription opioids, especially in the southern United States. Specifically, although initial rates were high and continued to increase alarmingly in West Virginia, they increased but then decreased in Florida. These descriptive data generate hypotheses requiring testing in analytic epidemiological studies. Understanding the divergent patterns of prescription opioid-related deaths, especially in West Virginia and Florida, may have important clinical and policy implications.

Starch-Ampicillin Agar for the Quantitative Detection of Aeromonas hydrophila

Interest in Aeromonas hydrophila as a food-borne and human pathogen is increasing. Isolation media from the clinical laboratory were evaluated for food use and either did not give quantitative recovery of A. hydrophila or did not permit ready differentiation of A. hydrophila from the background microflora. A new medium was developed which permitted quantitative recovery of A. hydrophila from foods. The medium consisted of phenol red agar base (Difco Laboratories), soluble starch (10 g/liter), and ampicillin (10 mg/liter). All foods surveyed contained A. hydrophila. Foods sampled included red meats, chicken, raw milk, and seafood (fish, shrimp, scallops, crab, and oysters). The count of A. hydrophila at the time of purchase ranged from 1 x 10/g (lower limit of detection) to 5 x 10/g. In most instances, the count of A. hydrophila increased during 1 week of storage at 5 degrees C. The starch-ampicillin agar developed permitted rapid quantitative recovery of A. hydrophila from foods in the presence of very large numbers of competing microflora.

Effect of temperature on the growth response of Salmonella enteritidis inoculated onto the vitelline membranes of fresh eggs

The growth response of Salmonella Enteritidis (SE) on the vitelline membrane in vitro was studied with the use of a special tube devised specifically for the inoculation of SE onto the vitelline membrane and for the sampling of the yolk near the inoculation site. This latter ability allowed the detection of the movement of SE into the yolk. The growth of SE on the membrane was compared with that of SE inoculated into yolk and albumen in vitro and in ovo in fresh in-shell eggs. The incubation time was 2 days, and the incubation temperatures were 4, 8, 15, 27, and 37 degrees C. Comparison of the results obtained for in vitro growth showed that at 4, 8, and 15 degrees C, SE behaved as if it were in the albumen, with its numbers decreasing over time. At 27 and 37 degrees C, SE grew as if it were in yolk, with a maximum increase of 4.5 log CFU after 2 days at 37 degrees C. In no experiments involving growth on the vitelline membrane did SE appear in the yolk. Comparisons between in vitro and in ovo growth responses of SE in yolk and albumen indicate that SE growth on the membrane parallels that in the in-shell egg.

Salmonella spp. and Escherichia coli biotype I on swine carcasses processed under the hazard analysis and critical control point-based inspection models project

The present study examined the prevalence of Salmonella spp. and the prevalence and quantity of generic (biotype I) Escherichia coli on carcasses or in pig feces at a pork processing plant operating under the hazard analysis and critical control point-based inspection models project (HIMP) program. The surfaces of carcasses were sponged on 10 separate days over a 30-day period at two processing steps: (i) immediately following exsanguination (100 carcasses), and (ii) after the carcasses were washed, eviscerated, and chilled overnight (122 carcasses). Feces were also collected from 60 of the 100 sponged, postexsanguinated pigs. Salmonella spp. were detected on 73.0% of the 100 postexsanguinated pigs, in 33.3% of the 60 fecal samples, and on 0.7% of the 122 chilled carcasses. E. coli was found on 100.0% of the postexsanguinated pigs and on 30.1% of chilled carcasses tested. The mean concentration of E. coli on carcasses was 1,700 CFU/cm2 immediately after the exsanguination step and 1.1 CFU/cm2 at the chilled carcass stage. Previous studies at this processing plant showed that the pre-HIMP baseline level of Salmonella spp. on the chilled carcasses was 0.8%, indicating that the present HIMP inspection system produced an equivalent level of bacteriological performance.

Effect of dehairing operations on microbiological quality of swine carcasses

To develop a hazard analysis and critical control point plan for food processing operations, critical control points must be determined. Swine slaughtering and dressing operations were investigated to establish their critical control points. We monitored the microbiology of swine carcasses by surface swabbing carcass bellies at various steps during the process and by quantitating total aerobic plate count (APC) and coliforms. Starting with a dehaired carcass, the sequential steps monitored included presingeing, postsingeing, polishing, and chilling. Initial results indicate that singeing and chilling substantially reduced the levels of APC and coliforms, whereas polishing increased their levels. The hygienic characteristics of individual operations involved in dressing swine carcasses were then evaluated in the second experiment. A set of 40 randomly selected carcasses leaving singeer, polisher, shaver, and washer were sampled. Carcasses were heavily contaminated during the final polishing procedure, and the APC increased threefold compared with prepolishing levels. Washing reduced the bacterial numbers by 69%. To reduce the microbial load on swine carcasses, final polishing and manual shaving steps were not used during the dressing operation on a set of 90 carcasses. APCs on singed carcasses were reduced from 1.34 to -0.15 log10 CFU/cm2 when the final polisher and manual shavers were not used. However, carcasses were subsequently recontaminated with bacteria after evisceration, and the APCs were similar (P > 0.05) regardless of whether the final polishing and manual shaving steps were used, averaging 1.30 and 1.46 log10 CFU/cm2. These results indicated that individual operations can be identified as critical control points, appropriate limits can be set and monitored in a hazard analysis and critical control point system, and steps where further changes to reduce bacterial levels may be needed for swine slaughtering plants.

Fate of gram-positive bacteria in reconditioned, pork-processing plant water

This study investigated the responses of Enterococcus faecium (ATCC 19433), Staphylococcus aureus (196E), and Listeria monocytogenes Scott A in water from a local meat-processing plant. Each bacterium was added to a starting count of 3 log10 CFU/ml and held from 5 to 28 degrees C. At intervals (0, 2, 7, 14, and 21 days), aliquots were plated on appropriate selective agars. In contrast to the gram-negative bacteria studied previously and which grew, the three gram-positive bacteria survived with some slight increase in number in only nonchlorinated, reconditioned water, either filtered (0.22 microm pore size) or nonfiltered. The presence of chlorine in either potable or reconditioned water contributed to the rapid decline in viable counts for all three bacteria. These results further emphasize the importance of residual chlorine in preventing the growth of these gram-positive bacteria in potable and reconditioned waters.

Thermal Resistance of Listeria monocytogenes and Salmonella spp. in Liquid Egg White

Survival of a five-strain mixture of Listeria monocytogenes and a six-strain mixture of Salmonella enteritidis , S. typhimurium , and S. senftenberg (not 775W) in liquid egg white was determined by a submerged-vial technique at 51.5°C and 53.2°C with 0.875% added H₂O₂ and at 55.5°C, 56.6°C, and 57.7°C with no additions. Survival at a range of pH values at 56.6°C also was determined. Surviving bacteria were counted on tryptic soy agar and results expressed as D-values; log-unit reductions in counts in 3.5 min or 6.2 min were calculated from these D-values. Plate pasteurization of commercially broken egg white (pH 8.8) inoculated with a single strain of L. innocua or S. senftenberg also was performed. Heating under currently approved pasteurization conditions, 51.5°C for 3.5 min with hydrogen peroxide, 55.6°C for 6.2 min, or 56.7°C for 3.5 min, resulted in a less than 3-1og unit reduction of viable Salmonella spp. and a less than 0.5-1og unit reduction of L. monocytogenes . At 53.2°C with peroxide, plate pasteurization resulted in a 3.44-1og unit reduction of S. senftenberg in 3.5 min. At 57.7°C with no peroxide, the D-value for Salmonella spp. was 0.78 min when heated in submerged vials, and plate pasteurization reduced viable numbers by 3.64 log units in 3.5 min. Destruction of Listeria under these conditions was still less than 1 log unit. Variation in the pH of the egg white from 7.8 to 9.3 resulted in D-values for Salmonella spp. at 56.6°C of 3.60 min to 1.08 min, respectively. D-values for L. monocytogenes under these conditions ranged from 10.4 min at pH 7.8 to 20.9 min at pH 9.3. The reduced heat sensitivity of Salmonella spp. at lower pH values should be considered in reevaluating pasteurization procedures.

Thermal Destruction of Listeria monocytogenes in Ice Cream Mix

Thermal destruction of Listeria monocytogenes strain Scott A was studied in refrigerated ice cream mixes to evaluate the relationship of mix composition to heat resistance with differing heat treatments. A central composite response surface design with two independent variables (high fructose corn syrup solids content and milkfat content) and one dependent variable (viscosity of the mix) was developed. High fructose corn syrup solids (HFCSS) content ranged from 1 to 7%, milkfat (MF) content from 4 to 18%, and total solids content from 28 to 44%. Sucrose content (11%) and milk-solids-not-fat content (10%) were kept constant. D_140°F values were established in the mixes with a simulated batch pasteurization procedure using closed vials. Survivor data indicated sigmoidal responses with initial shoulders and tailing, but shoulder values were not significantly affected by either HFCSS or MF. D and F (F = 7D + shoulder) values were significantly (p = 0.01, R² = .88; p = 0.01, R² = .89, respectively) correlated to HCFSS content with increasing heat resistance conferred at higher concentrations. MF content had little or no effect on thermal death time but had a greater effect on viscosity of the mix than did content of HFCSS. Increased thermal resistance of LM was associated with the common ice cream stabilizer used; stabilizer contained guar gum and carrageenan. Pasteurization guidelines for ice cream mix are adequate to ensure inactivation of LM. Since results suggest that major ingredients in ice cream, ice milk, and shake mixes increase thermal resistance of LM, it is important that every precaution be taken to inactivate the organism.

Characterization of the Aeromonas hydrophila group isolated from retail foods of animal origin

During a recent survey of retail fresh foods of animal origin (fish and seafood, raw milk, poultry, and red meats) for organisms of the Aeromonas hydrophila group, we isolated representative strains from the various foods. In this study, we sought to characterize these isolates for biochemical properties and virulence-associated factors and to compare the food isolates with clinical isolates. We identified all food and clinical isolates as A. hydrophila and found that all isolates were typical in their biochemical reactions. Examination of the isolates for various virulence-associated factors indicated that most food and clinical isolates were serum resistant, beta-hemolytic, cytotoxin positive (against Y1 adrenal cells), hemagglutinin positive, Congo red positive, elastase positive, and staphylolysin positive. Mouse 50% lethal doses were log10 8 to 9 CFU for most isolates. All isolates had biotypes identical to those of enterotoxin-positive strains. The public health significance of these organisms in foods is not known at present, although their widespread occurrence and ability to grow competitively in foods kept at 5 degrees C represents a potential hazard.

The growth of Aeromonas hydrophila K144 in ground pork at 5 degrees C

The influence of NaCl, pH, atmosphere, and background microflora on the growth and/or survival of Aeromonas hydrophila K144 was studied in ground pork held at 5 degrees C. In ground pork, A hydrophila was sensitive to pH values below 6.0 in the form of either a low starting pH in the pork itself or induced by lactic acid bacteria action on added glucose. Growth of the organism is inhibited by NaCl levels of 3% (w/w) (approx. 4% brine content). A hydrophila grew in vacuum-packaged ground pork; its growth was diminished by the presence of the naturally occurring meat microflora. Except for pH values below 6.0, conditions which inhibited growth permitted survival of the organisms for extended periods. Data indicate that the growth of A. hydrophila in ground pork can be controlled by factors such as NaCl, pH, and background microflora. In general, measures designed to control other foodborne pathogens appear adequate to limit A. hydrophila.

Thermal Resistance of Aeromonas hydrophila

Thermal resistance of five strains of Aeromonas hydrophila (three clinical and two food isolates) was studied at 45 to 51°C in saline solution and raw milk. In addition, effects of growth temperature and growth phase on thermal resistance of the cells were also studied. Survivors after various heat treatments were plated on starch phenol red agar; colonies were counted after 24 h at 28°C. Cells heated at 48°C and 51°C exhibited a diphasic response and the data presented are from the initial and final linear phases. Data were expressed as D- and z-values. Most variables caused small but statistically significant changes in D-value of the initial linear phase. At 48°C, D-values for stationary phase cells heated in saline solution ranged from 3.49 to 6.64 min; for cells heated in raw milk, the D-values ranged from 3.20 to 6.23 min. At 48°C, D-values for log-phase cells heated in saline solution ranged from 2.23 to 3.73 min, and z-values ranged from 5.22 to 7.69°C. These results indicate that A. hydrophila should be killed by many of the heat treatments given foods during processing. The thermal resistance of A. hydrophila appears similar to that of other gram-negative bacteria associated with food.

Heat injury and repair in Campylobacter jejuni

A procedure for detecting and quantitating heat injury in Campylobacter jejuni was developed. Washed cells of C. jejuni A7455 were heated in potassium phosphate buffer (0.1 M, pH 7.3) at 46 degrees C. Samples were plated on brucella agar supplemented with Na2S2O3, FeSO4 X 7H2O, and sodium pyruvate and on a medium containing brilliant green, bile, Na2S2O3, FeSO4 X 7H2O, and sodium pyruvate. Colonies were counted after 5 days of incubation at 37 degrees C in an atmosphere containing 5% O2, 10% CO2, and 85% N2. After 45 min at 46 degrees C, there was virtually no killing and ca. two log cycles of injury. Cells grown at 42 degrees C were more susceptible to injury than cells grown at 37 degrees C. The addition to brucella agar supplemented with Na2S2O3, FeSO4 X 7H2O, and sodium pyruvate of three different antibiotic mixtures used in the isolation of C. jejuni from foods or clinical specimens did not prevent recovery of heat-injured C. jejuni. Cells lost 260 nm of absorbing materials during heat injury. The addition of 5% NaCl or 40% sucrose to the heating buffer prevented leakage but did not prevent injury. Of the additional salts, sugars, and amino acids tested for protection, only NH4Cl, KCl, and LiCl2 prevented injury. Heat-injured C. jejuni repaired (regained dye and bile tolerance) in brucella broth supplemented with Na2S2O3, FeSO4 X 7H2O, and sodium pyruvate within 4 h. Increasing the NaCl in this medium to 1.25% inhibited repair, and increasing it to 2% was lethal. Heat-injured C. jejuni will repair at 42 degrees C but not at 5 degrees C.

Heat injury in Staphylococcus aureus 196E: protection by metabolizable and non-metabolizable sugars and polyols

Polyols and sugars, which were not metabolized (O2 uptake or fermentation was not demonstrated), protected Staphylococcus aureus 196E against heat injury as well as metabolized compounds. Inhibitors of glucose metabolism decreased O2 uptake with glucose but did not affect the protective ability of glucose against heat injury.

Effect of Food Environment on Staphylococcal Enterotoxin Synthesis: A Review

Effects of various nutritional and environmental factors on growth and enterotoxin synthesis by Staphylococcus aureus in model systems and foods are reviewed. Factors discussed include effects of inoculum size, competing microflora, gaseous atmosphere, carbon source, temperature, pH, sodium chloride, water activity, mineral ions and sublethal stress. Areas where additional research is needed are also discussed.

Protection Against Heat-Injury in Staphylococcus aureus by Solutes

The effect of solutes on heat-injury in Staphylococcus aureus 196E was studied in 25% ground beef (GB) slurry or distilled water equilibrated at 49 C. Exposure to 49 C for 90 min resulted in a 3-4 log cycle increase in injured cells. The number of injured cells was the difference between bacterial counts on tryptic soy agar (TSA) + 1% pyruvate and TSA + 9% NaCl. Increasing levels of NaCl (1-9%) added to GB slurry gave increasing protection against heat-injury and resulted in a decrease in the number of injured S. aureus ; glycerol and sucrose had a similar effect. At 0.85 M (equivalent to 5% NaCl), other compounds such as sodium citrate, KCl, NaNO₃, Na₂SO₄, Na₂HPO₄, NH₄Cl, CaCl₂, and LiCl were more effective than NaCl in protecting against heat injury; sodium acetate, MgSO₄, NaI, MnCl₂, MgCl₂, NaBr, NaH₂PO₄, and KI were less effective than NaCl. In the presence of 5% NaCl, it was necessary to raise the temperature from 49 to 55 C to obtain significant heat-injury to S. aureus . Addition of NaCl prevented the leakage of UV-absorbing materials and decreased the extent of magnesium ion leakage from heat-injured staphylococci.

Microbiology and Composition of Snack Sausages

Chemical, bacteriological and processing characteristics of experimental and commercial snack sausages were investigated. Snack sausages are narrow diameter (ca. 10-12 mm), all-beef products which are relatively dry and shelf-stable, and which may or may not be fermented. The bacterial flora of each product consisted of gram-positive, catalase-positive sporeforming rods (bacilli), reflecting a time-temperature effect of heating/smoking which destroyed most other organisms. The products have low moisture content (av. 20.6%), water activity (av. 0.78), and moisture/protein (M/P) ratio (av. 0.81/1). Judged by the sausage classification system of Acton and Dick relating moisture content to M/P ratio, the snack sausages are fully dry products. The yield of snack sausage prepared in our pilot plant was 39.6% but increased to 51.4% when the initial fat content of the meat mixture was increased from 7.2 to 25.7%.

Injury to Staphylococcus aureus during sausage fermentation

Staphylococcus aureus 196E added to a beef sausage containing starter culture and 0.5 to 2.0% glucose and incubated at 35 degrees C was unable to grow when plated on tryptic soy agar (TSA) containing 7.5% NaCl. The injury, presumed to be due to the lactic acid produced during fermentation, was more pronounced at the lower concentrations of glucose (and lower acid levels). In the absence of glucose and/or starter culture, no injury was observed. When sausages containing S. aureus injured by fermentation at 35 degrees C were incubated at 5 degrees C, the counts on TSA (measures both injured and uninjured cells) and TSA containing 7.5% NaCl (measures uninjured cells only) remained constant; however, upon reincubation of the cold-stored sausage at 35 degrees C, the staphylococcus counts on TSA and TSA containing 7.5% NaCl and were similar to the counts of S. aureus present in fermenting sausages that had never been subjected to 5 degrees C. The demonstration of acid injury indicated that the injury phenomenon must be considered when determining numbers of viable S. aureus in fermented sausages.

Destruction of Staphylococcus aureus during frankfurter processing

We studied the thermal resistance of Staphylococcus aureus during frankfurter processing in respect to whether staphylococci are killed by the heating step of the process and whether heat injury interferes with the quantitative estimation of the survivors. With S. aureus 198E, heat injury could be demonstrated only when large numbers of cells (10(8)/g) were present and at a product temperature of 140 degrees F (60 degrees C). On tryptic soy agar and tryptic soy agar plus 7% NaCl media, at temperatures less than 140 degrees F, the counts were virtually identical; above 140 degrees F, the counts converged, with the organisms dying so rapidly that heat injury was not demonstrable. Heat injury was thus judged not to interfere with the quantitative estimation of staphylococci surviving the normal commercial heating given frankfurters. By using a combination of direct plating on tryptic soy agar and a most-probable-number technique, we detected no viable cells (less than 0.3/g) of several strains of S. aureus in frankfurters heated to 160 degrees F (71.1 degrees C). This temperature is compatible with the normal final temperature to which federally inspected processors heat their frankfurters and with the temperature needed to destroy salmonellae.

Destruction of Salmonella and Staphylococcus During Processing of a Nonfermented Snack Sausage

Survival of Salmonella dublin , Salmonella senftenberg 775W, Staphylococcus aureus 196E, and S. aureus 184 was studied during processing of an inoculated beef, nonfermented snack sausage. No viable staphylococci or salmonellae were detected in sausages that had been heated at an internal temperature of 53.9-55.0 C or 57.8-58.9 C for 3.5 h followed by drying at 21 C and 50-55% relative humidity for 4 days. Heating at an internal temperature of 51.1-52.2 C for 3.5 h followed by drying did not produce a salmonellae- or staphylococci-free sausage.

Survival of salmonellae during pepperoni manufacture

Survival of salmonellae in artificially contaminated beef-pork mixtures (approximately 10(4) salmonellae/g) was studied in pepperoni prepared by either a natural flora or lactic starter culture fermentation or in nonfermented sausages. The pepperoni did not become salmonellae free during the usual commercial 15 to 30-day drying period. Salmonella dublin was present in all products, fermented or unfermented, after 42 to 43 days of drying. At a lower level of contamination, 10(3)/g, S. dublin could not be recovered from starter culture-fermented pepperoni after 14 days of drying but persisted in the natural flora-fermented sausage. S. typhimurium (initial count, 10(4)/g) was absent after 42 days of drying when starter culture was used to ferment the pepperoni, but was still present in the natural flora-fermented and unfermented products. S. dublin, host adapted to cattle, or S. choleraesuis, host adapted to swine, had similar survival patterns in beef pork, or beef-pork pepperoni. Heating salmonellae contaminated beef-pork pepperoni (after fermantation but before drying) to an internal temperature of 60 C (trichinae inactivating) eliminated the food-borne pathogen from the sausage product.

Microbiology of the frankfurter process: salmonella and natural aerobic flora

Salmonella senftenberg 775W added to frankfurter emulsion was killed during normal processing in the smoke house when internal product temperature was 71.1 C (160 F) or above. The thermal destruction point of S. senftenberg 775W in frankfurters (temperature at which no viable cells were detected) was a function of the length of time of the process rather than of the starting number of cells. Heating of frankfurters to 73.9 C (165 F) substantially reduced the total non-salmonella count. For total non-salmonella bacterial flora and salmonella, relatively little thermal destruction occurred below 43.3 C (110 F). The heating step can bring about a 7-log cycle decrease (10(8) to 10(1)/g) of bacteria present in the raw emulsion. The flora of this high-bacteriological-count raw emulsion was predominantly gram-negative rods. Variation in the number of bacteria (both total and salmonella) surviving at various temperatures during processing was attributed to slight variations in the temperature pattern of the smoke house during its operation. An integration process was devised which allowed calculation of exposure to temperatures above 110 F (43.3 C) on the basis of degree-minutes. Plots of degree-minutes versus log of surviving bacteria were linear. The salmonella plot had a greater slope than that of the total non-salmonella flora, indicating that salmonellae are more heat sensitive than the bacterial population as a whole. The predominant bacteria surviving the heating step were micrococci. These micrococci were able to increase in number in or on the frankfurters during storage at 5 C.

Microbiology of Lebanon bologna

Various aspects of the microbiology of the Lebanon bologna process were studied. Manufacture of Lebanon bologna appeared to be similar to that of summer sausage and other fermented sausages and consisted of a lactic acid fermentation by lactobacilli accompanied by the production of cured meat color from the reduction of nitrate by micrococci. The traditional process consists of aging coarse ground beef at 5 C for several days. Aging the beef for about 10 days was necessary to allow development of lactic acid bacteria; for successful fermentation, the concentration of lactic acid producers must be 10(4)/g or more. At least 3% NaCl was necessary to suppress the development of pseudomonads during the aging period; higher concentrations of salt suppress the development of the lactic acid-producing flora. During aging, in the presence of salt, the predominant flora developing on the meat consisted of catalase-positive, gram-positive rods and cocci; during fermentation at 35 C, the predominant flora became catalase-negative, gram-positive rods with characteristics of lactobacilli. Lebanon bologna could be made from frozen beef if the meat was thawed, salted, and aged. However, bolognas could not be made from unaged beef unless a lactic acid starter culture was used. The microflora of several commercial bolognas is reported also.

Influence of sulfite on growth, slime, and fluorescent pigment formation by Pseudomonas aeruginosa

Substitution of sulfite for sulfate in the defined pyocyanine medium of Frank and DeMoss 1959 allowed formation of fluorescent pigments and slime by Pseudomonas aeruginosa NRRL B-4014. This formation of fluorescent pigments was both pH and iron dependent. The unadjusted medium (pH 8.25) containing sulfite and Fe3+ allowed both growth and fluorescent pigment formation. Growth and fluorescent pigment formation were observed from a pH of 9.0 down to a pH of 7.5. At pH 7.5, the concentration of HSO3− is 6 × 10−4 M, and this ion appears to be the active agent in inhibiting growth below pH 7.5. When the medium was adjusted to pH 7.0, neither fluorescent pigment formation nor growth was observed. The acid used for pH adjustment did not influence the minimum pH for growth. In the presence of small amounts of iron (ca. 1 × 10−6 M Fe3+), the organism shifted from a blue to a yellow-green fluorescent pigment. Cultural conditions such as temperature and nutrients which supported growth also supported slime formation as well as fluorescent pigment formation.

Role of iron and sulfur in pigment and slime formation by Pseudomonas aeruginosa

Media and an analytical scheme have been developed which allow both a qualitative and quantitative estimation of the formation of pyocyanine, related phenazines, pyorubrin, and a blue and a yellow-green fluorescent pigment by Pseudomonas aeruginosa. Use of the defined pyocyanine medium of Frank and DeMoss with sulfate or various organic sulfur sources allowed formation of pyocyanine, related phenazines, and pyorubrin. When sulfite was the sulfur source with or without iron, P. aeruginosa formed either a yellow-green or a blue fluorescent pigment. Formation of fluorescent pigments of P. aeruginosa is related to the ability of sulfite to act as a specific sulfur source. In an investigation of the role of both added iron and sulfur sources, complex patterns of pigment formation were observed. In addition to the fluorescent pigments, sulfite also supported the formation of slime by P. aeruginosa.

Inhibitory action of tetrathionate enrichment broth

Tetrathionate enrichment broth is a complex mixture of salts including iodides and other polythionates, but only thiosulfate (0.0736 m) and tetrathionate (0.0236 m) in combination were toxic for Escherichia coli. Individually, these two salts were not lethal. The lethal action of this thiosulfate-tetrathionate mixture affected only growing cells. A possible relationship between the lethality of the thiosulfate-tetrathionate mixture for a culture and its ability to reduce tetrathionate is suggested.

Influence of temperature on steady-state growth of colonies of Pseudomonas fluorescens

Diameters of surface colonies of Pseudomonas fluorescens were observed to increase linearly with time at temperatures from 30 to 0 C.

The influence of temperature on the pathways of glucose catabolism in Pseudomonas fluorescens

The influence of temperature on the pathways of glucose catabolism in Pseudomonas fluorescens has been investigated using the radiorespirometry method. When grown in continuous culture with limiting concentrations of glucose, the organism metabolized 86% of the glucose via the Entner–Doudoroff pathway at 30, 20, and 8 C. The remaining glucose, 14%, was metabolized via the hexose monophosphate pathway. When the organism was grown on non-limiting concentrations of glucose at 8 C, a major shift in pathways of glucose catabolism was observed. Fifty-seven percent of the glucose was degraded via the hexose monophosphate pathway and only 43% via the Entner–Doudoroff pathway. A change in temperature altered the pathways of glucose catabolism by regulating the growth limiting concentration of glucose rather than by directly affecting the respective enzyme activities of the pathways.

Influence of temperature on glucose utilization by Pseudomonas fluorescens

The influence of temperature on the conversion of glucose into cell material and into energy for maintenance was determined for Pseudomonas fluorescens by a steady-state turbidity method and by a substrate utilization method. Conversion of glucose into cell material was measured as yield; conversion of glucose into energy for maintenance was measured as specific maintenance, the minimum dilution rate in continuous culture below which a steady state is not possible. The values obtained by the two methods were nearly identical; with both, the yield and specific maintenance decreased with decreasing temperature. The specific maintenance consumption rate (milligrams of glucose taken up per milligram of cell dry weight per hour at zero growth) was also calculated by the substrate utilization method and found to decrease with decreasing temperature. However, the amount of glucose consumed per generation for maintenance increased with decreasing temperature. This increased glucose consumption for maintenance may provide a partial explanation for the decrease in yield at low temperatures. Small amounts of glucose were also converted into pigment at all temperatures tested, with the greatest amount formed at 20 C.

Interaction of salt, pH, and temperature on the growth and survival of salmonellae in ground pork

The interaction of temperature, pH, and NaCl concentration on the growth and survival of several strains of salmonellae has been determined in broth and ground pork. Growth of 23 strains occurred in broth at 30 C over a wide range of pH-NaCl combinations; at 10 C, growth was limited to only a few combinations. Cultures which would not grow at 10 C because of the pH-NaCl effect survived for long periods, however. In contrast, cultures which would not grow at 30 C remained viable for only a short time. Results in fresh ground pork were in close agreement with the broth studies. Salmonellae would not grow in ground pork stored at 4 C but would grow in pork containing 3.5% salt stored at 10 C. Salmonellae grew competitively with the natural background flora at 10 C even when the salmonellae constituted less than 5% of the initial flora, and the background flora would grow at a lower temperature than the salmonellae. The data show that, whereas decreasing temperatures increase the inhibitory effects of pH and NaCl, they decrease the lethal effects.

Culture aeration in a polythermostat

A system for the aeration of cultures growing in a polythermostat temperature-gradient block was developed. This system provided both aeration and agitation of the cultures, while allowing the growth to be followed spectrophotometrically. The necessity for aeration of cultures growing in a polythermostat was experimentally shown.