Outpatient management of proctologic disease. Which techniques for local anesthesia? The experience of a single center.

INTRODUCTION: Since 1899 outpatient management of surgical patients had been increasing, becoming the best option when possible. In 1988 was described the first experience of outpatient management of proctologic disease. Advances in local anesthesia techniques have improved the outpatient approach to surgical disease, particularly in patients with proctological diseases. METHODS: From 2010 to 2016, 1160 patients who needed surgery for proctologic disease have been recruited: 239 hemorrhoidectomies using the variant of Milligan Morgan technique described by Phillips, 45 trans-anal hemorrhoidal DE-arterialization (THD), 315 sphincterotomies, 12 anal polypectomies, 230 loop seton positions, 65 cone-like fistulectomies and 254 fistulotomies for perianal fistulas. In 329 cases, we used the posterior perineal block, 603 local perineal blocks, and 228 tumescent anesthesia. RESULTS: On a total of 1160 procedure failure rate was of 4.7% (55 cases). Urinary retention (69% 38 cases); bleeding 18% (10 cases), uncontrolled pain 12% of cases (7 cases). The chi-square test demonstrates (p<0.01) that the failure rate of the three types of anesthesia is very different with high statistical significance. The failure rate in patient underwent Posterior Perineal Block was 27/329 cases (8.2%), 8/228 (3.5%) in patients who underwent Tumescent Anesthesia and 20/603 (3.3%) in who underwent Local Perineal Block. CONCLUSIONS: Outpatient protocols represent the most common approach to minor proctologic disease that needs a good local block, with a good analgesic and sedative assistance, the different local block seems to be the same concerning the pain control, but presents some little, not relevant difference concerning urinary retention rate.

Mapping the centers performing endocrine neck surgery in Italy.

BACKGROUND: Quality of care and provider's experience seem to be strictly connected in any field of surgery. Aim of this study is to identify a method to classify the centers on the basis of the number of thyroidectomies and parathyroidectomies performed. METHODS: We listed 666 centers performing endocrine neck surgery in 2015, from the database of the Italian Health Ministry. We performed a descriptive statistic analysis with a dedicated software. We identified the outliers, according to a previous literature review, in those centers performing >1000 and < 10 thyroidectomies, >100 and < 3 parathyroidectomies and we excluded them to our analysis. The remaining centers were grouped in a box-plot. Third quartile, median, procedures performed/3rd quartile value ratio (Standardized Hospitalization Ratio, SHR, superior cut-off), Romamedian/3rd quartile values ratio (inferior cut-off) were calculated. These centers were charted in a bar graph and three zones were identified: "excellence" (SHR>1.1), "SHR", "alert" (between the two cut-offs) and "risk" (under the lower cut-off). RESULTS: 35743 thyroidectomies and 2306 parathyroidectomies were performed in Italy in 2015. After the outliers' exclusion, 407 and 157 centers performing respectively thyroidectomies and parathyroidectomies were analysed. A median value of respectively 37 thyroidectomies and 6 parathyroidectomies, and a 3rd quartile cut-off of respectively 85 and 12 were calculated. Concerning all the 666 centers, we found: 95 excellence centers for thyroidectomy and 33 for parathyroidectomy, respectively 18 and 17 falling into superior cut-off line, 100 and 29 in the alert zone, 453 and 587 in the risk zone. CONCLUSIONS: Our method, according to the literature data, highlighted a number of thyroidectomies and parathyroidectomies performed in low volume centers. Looking for an optimization in health organization, we can consider some measures such as a net of tutorship of the "alert" hospitals by the excellence ones and a discouragement of the "risk" hospitals in performing endocrine neck surgery.

P-POSSUM score: a prognostic instrument for postoperative complications in Crohn's disease.

AIM: The purpose of this work is to demonstrate the correlation between the p-POSSUM score and the severity of Crohn's Disease (CD) postoperative complications, evaluated by using the Clavien-Dindo score. PATIENTS AND METHODS: We have selected data of 22 patients (11 males, 11 females) that had been recovered in the Operative Unit of General Surgery of the University of Palermo General Hospital and undergone surgery for CD from 2010 to 2017. RESULTS: Patients who underwent surgery for complicated CD was divided in three different group on the base of Clavien Dindo score, C1 (Clavien-Dindo ≤ 1), C2 (Clavien Dindo = 2), and C3 (Clavien Dindo ≥ 3). ANOVA one way statistic analysis was used to investigate the presence of statistic difference in the mean of p-POSSUM operative score between the three groups of patients who underwent surgery for complicated CD. Results show that the severity of postoperative complication after surgery for complicated CD is related to the value of p-POSSUM score (p = 0,004965). CONCLUSIONS: This study clearly demonstrates a statistic correlation between p-POSSUM operative score and the risk of occurrence of severe postoperative complications in patients with Crohn's disease that had been undergone to surgical procedures of resection with ileostomy and percutaneous drainage.

Surgeon volume and hospital volume in endocrine neck surgery: how many procedures are needed for reaching a safety level and acceptable costs? A systematic narrative review.

The relationship between quality of care and provider's experience is well known in all fields of surgery. Even in thyroidectomies and parathyroidectomies, the emphasis on positive volume-outcome relationships is believed. It led us to an evaluation of volume activity's impact in terms of quality of care. A systematic narrative review was performed. According to the PRISMA criteria, we selected 87 paper and, after the study selection was performed, 22 studies were finally included in this review. All articles included were unanimous in attributing to activity volume of surgeons as well as centers a substantial importance. Some differences in outcomes between these investigated categories have been found: best results of the high volume surgeon is evident expecially in terms of complications, on the contrary best outcomes of a high volume center are mainly economics, such as hospital stay and general costs of the procedures. A cut-off of 35-40 thyroidectomies per year for single surgeon, and 90-100 thyroidectomies for single center appears reasonable for identifying an adequate activity. Concerning parathyroidectomy, we can consider reasonable a cut off at 10-12 operations/year. More studies are needed in a European or more circumscribed perspective.

Pathogenesis and inflammatory response in experimental caprine mastitis due to Staphylococcus chromogenes.

Coagulase-negative staphylococci (CNS) are the most frequently isolated bacteria in cases of subclinical mastitis in dairy cows. CNS species may differ in their pathogenicity, but very little is known about their virulence factors or their immune response in intramammary infections. To our knowledge, no experimental studies into the mastitis pathogenesis caused by CNS have been described in lactating goats. The aim of this study was to induce an experimentally Staphylococcus chromogenes mastitis in lactating goats aimed at verifying if the model can be used to evaluate the inflammatory response, the dynamics of infection and the pathological findings within the first hours of intramammary inoculation. Six Saanen goats in mid-lactation were inoculated with 1 × 107 colony forming units of S. chromogenes. Bacterial growth peaked in milk from the challenged right halves of the mammary glands (RMG) at 4 h post inoculation (PI). Shedding of viable bacteria showed a marked decrease at 12 h PI. An increase in mean somatic cell counts was observed in the milk samples from 8 h PI onwards. Mild clinical signs were evoked by intramammary inoculation. Staphylococcus chromogenes could be isolated in tissue from all RMG. Histological examination of specimens of the RMG and lymph nodes of the goats showed an increased inflammatory response throughout the experiment with respect to control halves. In conclusion, the experimental inoculation of S. chromogenes in lactating goats is capable of eliciting an inflammatory response and capable of causing pathological changes. This research represents a preliminary study for a better knowledge of the mastitis pathogenesis caused by S. chromogenes.

Non-functioning parathyroid cystic tumour: malignant or not? Report of a case.

Parathyroid carcinoma (PC) is a very rare endocrine tumour, usually characterized by symptoms such as a neck mass, dysphonia, severe hypercalcemia exceeding 140 mg/L and elevated serum parathyroid hormone levels, even more than 5 times the upper limit of normal. Non-functioning parathyroid cancer is extremely rare and, in this case, its pre-operative diagnosis is often difficult. A 54-year old female patient, referring dysphagia and dysphonia, underwent neck ultrasound and neck CT. A left thyroid nodule, probably cystic, was found. It presented caudal extent on anterior mediastinum causing compression of the left lateral wall of the trachea. The preoperative calcemia was into the normal range. The patient underwent left thyroid lobectomy. Histological exam showed a cystic lesion, immunohistochemically originating from parathyroid that oriented for carcinoma. The 18 months follow-up did not show a residual-recurrent disease. The parathyroid origin of a neck lesion could not be suspected before surgery when specific laboratory tests are not available and clinical effects of hyperparathyroidism syndrome are not present. Histological features are not always sufficient for the differential diagnosis between the parathyroid adenoma and carcinoma. The immunohistochemistry is an useful tool that can aid to reach the definite diagnosis.

Non-Occlusive Mesenteric Ischemia (NOMI) in Parkinson's disease: case report.

Non-occlusive mesenteric ischemia (NOMI) is a severe pathological condition characterized by signs and symptoms of bowel obstruction, intestinal necrosis resulting from acute and/or chronic inadequate blood perfusion, in the absence of an organic vascular obstruction detectable by imaging techniques. A 64 years old man case with a history of Parkinson's disease in high-functioning levodopa treatment is presented. Clinical and radiological signs of intestinal obstruction were observed. He underwent surgical operation with total colectomy and terminal ileostomy for generalized secondary peritonitis due to perforation of sigmoid colon. Ischemic pancolitis was first suspected. In third post-operative day a contrastenhanced CT scan was performed in the evidence of fever and sub-occlusive symptoms. It was found absence of reliable evidence of vascular changes; superior mesenteric artery and vein patency is maintained A NOMI was then diagnosed. NOMI represents about 0.04% of mesenteric artery diseases. It is correlated with a poor prognosis with a mortality estimated of 70-90%. Parkinson's disease, considering neurodegenerative alterations that characterize it, can be considered as a predisposing factor. The combined treatment with high doses of levodopa and vasodilators, such as PGE (Prostaglandin E), can contribute to an improvement in prognosis.

23-hour observation endocrine neck surgery: lessons learned from a case series of over 1700 patients.

Although the surgical procedures concerning the thyroid and the parathyroid glands are considered safe, the possible occurrence of complications (mainly hematoma and hypocalcemia) limit the short stay surgery. At our institution a 23-hour-surgery with overnight hospital stay for endocrine neck surgical procedures was introduced since 2004. The present case series analyses the institutional results. Over 1913 endocrine neck surgery procedures, 1730 patients (90,2%) were managed according to this model. Among these patients, 92 suffered from hypocalcemia, 12 from airways obstruction due to the hematoma, 5 from bilateral nerve palsy. 15 more patients had unpredictable general disease compromising the short-stay surgery management. The goal of the discharge after 23 hours was achieved in 92,8% of cases with a mean hospital stay of 1,1days. The 23-hour observation with an overnight surgery is feasible and safe if the correct indications are observed. A considerable volume of specific activity is needed.

The non-surgical management for hemorrhoidal disease. A systematic review.

The non-surgical treatments for hemorrhoids are cost and time-saving techniques usually performed in patients suffering early hemorrhoidal disease. The most used are rubber band ligation (RBL), injection sclerotherapy (IS), and infrared coagulation (IRC). We performed a systematic review in order to evaluate: do these procedures really help to avoid further more aggressive treatments? What are the common harms? What are the rare harms? How many recurrences there are? A total of 21 RCTs were included in this review: 12 on RBL, 4 on IRC and 5 on IS. In RBL bleeding stops in up to 90% and III degree hemorrhoids improves in 78%-83.8%. IV degree prolapse should have a more invasive treatment. The commonest complications are bleeding and pain (8-80%). IRC related improvement is 78%, 51% and 22% for I, II and III degree. Post-operative pain occurs in 15-100% and post-operative bleeding ranges from 15% to 44%. Recurrence rate is 13% at a three months follow-up. IS brings to the resolution of prolapse in 90%-100% of II degree and allows good results for III degree even if reported only by case series. The post-procedural pain is 36%-49%. Bleeding is a very rare harm. Even if not definitive, these treatments could be an alternative for mild symptomatic patients after a clear explanation of recurrence rates and possible complications.

Deep SSI after mesh-mediated groin hernia repair: management and outcome in an Emergency Surgery Department.

AIM: Mesh-mediated groin hernia repair is considered the goldstandard procedure. It has low recurrence rate. Rarely a deep Surgical Site Infection (SSI) is seen when a synthetic prosthesis is used. CASE REPORT: We describe a rare case of bilateral deep SSI after mesh-mediated groin hernia repair. Diagnosis was performed through the physical examination and radiological exams. Microbiological samples identified a methicillin-resistant Staphylococcus aureus responsible of the infection. Target therapy was performed and re-operation performed in order to remove the infected prosthesis and to apply a biological one to create the fibrous scaffold. During follow-up time, right side recurrence was observed. Tru-cut biopsy of fascia was obtained in order to identify the responsible of the recurrence. CONCLUSION: Combination of antibiotic therapy and surgical reoperation seems to be the correct way to approach the deep SSI after mesh-mediated groin hernia repair. The use of biological mesh after synthetic removal seems to improve the final outcome.

Long-term esophageal motility changes after thyroidectomy: associations with aerodigestive disorders.

BACKGROUND: Patients undergoing thyroidectomy often complain aerodigestive disorders. In a previous study we showed the associations between voice impairment and proximal acid reflux, swallowing impairment and Upper Esophageal Sphyncter (UES) incoordination and the decrease in UES pressure in thirty-six patients observed before and soon afterwards uncomplicated thyroidectomy. This study investigated the state of post-thyroidectomy esophageal motility changes and its associations with these disorders after 18-24 months. PATIENTS AND METHODS: The thirty-six patients prospectively recruited according to selection criteria (thyroid volume ≤60 ml, benign disease, age 18-65 years, previous neck surgery, thyroiditis, pre- or postoperative vocal cord palsy) underwent voice (VIS) and swallowing (SIS) impairment scores, esophageal manometry and pH monitoring once again. RESULTS: After 18-24 months, both VIS and SIS recovered (respectively: p=0,022; p=0,0001); UES pressure increased (p=0,0001) nearing the preoperative values. The persistence of swallowing complaints were associated with the persistence of esophageal incoordination (p=0,03); the association between voice impairment and proximal acid reflux was confirmed (p<0,001). CONCLUSIONS: Our study confirms that aerodigestive disorders after uncomplicated thyroidectomy, largely transient, are strictly connected with upper esophageal motility changes. In this viewpoint, the innervation of upper aerodigestive anatomical structures (larynx, pharynx, upper esophagus) and its variations should be focused.

Laparoscopic treatment of a large pedunculated hemangioma of the liver: a case report.

Hepatic hemangiomas are the most common benign tumors of the liver, often asymptomatic and discovered incidentally. A 62-year-old woman was referred to our Institution under the suspicion of having an 8 cm-sized GIST. Due to the atypical features of the lesion on TC scan, a biopsy was performed. We report the case of pedunculated hepatic hemangioma with the aim to discuss the diagnostic approach, the possible causes of misdiagnosis and the opportunity of the laparoscopic approach.

Acute appendicitis: should the laparoscopic approach be proposed as the gold standard? Six-year experience in an Emergency Surgery Unit.

Acute appendicitis is common in an Emergency Surgery Unit. Although the laparoscopic approach is a method accepted for its treatment, no strong data are available for determining how many procedures must an experienced surgeon carry out for obtaining all the advantages of this technique and if this approach can become the gold standard in the activity of a general emergency unit with senior surgeons variously skilled on the basic laparoscopy. 142 patients that underwent appendectomy (90 laparoscopic, 52 conventional) for acute appendicitis were enrolled in this institutional retrospective cohort study. The surgeons were classified with a descriptor-based grading and divided in two groups regarding the skill. The only relevant result of our study was the significant reduction of conversion rate in case of laparoscopic approach. No strong differences were found concerning the duration of the procedure and the hospital stay between the two groups. The rate of complications were very low in both groups. In conclusion, the experienced surgeons can easily perform a laparoscopic approach independently from the specific skill in this approach.

The coexistence of primary hyperparathyroidism and thyroid nodules: should the preoperative work-up of the parathyroid and the thyroid diseases be specifically adjusted?

INTRODUCTION AND OBJECTIVES: Primary hyperparathyroidism (PHPT) can be found in concomitance with thyroid disease (TD) in a high frequency of cases. In this context the diagnostic exams for localizing the enlarged parathyroid(s) gland(s) could be less reliable or nonconclusive. Moreover, the thyroid carcinoma seems to be more frequent compared to that isolated thyroid desease and, therefore, carefully investigated. The main goal of the present study is to evaluate which diagnostic tool (US, MIBI) is more reliable for localizing the site of the PTH hypersecretion and to confirm if it is always advantageous a combination of both exams. Besides, we evaluated the incidence of thyroid carcinoma in our series of patients. PATIENTS AND METHODS: A review of available data of 73 patients who underwent total thyroidectomy + parathyroidectomy from 2003 and 2014 was performed. The preoperative workup included systematically US and MIBI whose results were considered true positive when at least the side (left/right) of the parathyroid affected were concordant with the surgical report, settled as the gold standard, according to the Cox nonnested model. The connection between the diagnostic results of US versus MIBI was calculated with the Cohen K index for evaluating their overlap. The average of the thyroid carcinoma were also calculated. RESULTS: The difference between respectively US versus surgical report (p value=0.73) and MIBI versus surgical report (p value=0.81) were not significant. The low Cohen K index showed that both US and MIBI are complementary. In 23 patients (32,9%) a thyroid carcinoma was found. CONCLUSIONS: The association of MIBI and neck US is mandatory in the first evaluation of patients undergoing thyroidectomy and parathyroid excision simultaneously. The high prevalence of thyroid carcinoma in this specific context suggests a more aggressive diagnostic and surgical behaviour.

Comparison of minimally invasive parathyroidectomy under local anaesthesia and minimally invasive video-assisted parathyroidectomy for primary hyperparathyroidism: a cost analysis.

BACKGROUND: Primary hyperparathyroidism (PHPT) origins from a solitary adenoma in 70- 95% of cases. Moreover, the advances in methods for localizing an abnormal parathyroid gland made minimally invasive techniques more prominent. This study presents a micro-cost analysis of two parathyroidectomy techniques. PATIENTS AND METHODS: 72 consecutive patients who underwent minimally invasive parathyroidectomy, video-assisted (MIVAP, group A, 52 patients) or "open" under local anaesthesia (OMIP, group B, 20 patients) for PHPT were reviewed. Operating room, consumable, anaesthesia, maintenance costs, equipment depreciation and surgeons/anaesthesiologists fees were evaluated. The patient's satisfaction and the rate of conversion to conventional parathyroidectomy were investigated. T-Student's, Kolmogorov-Smirnov tests and Odds Ratio were used for statistical analysis. RESULTS: 1 patient of the group A and 2 of the group B were excluded from the cost analysis because of the conversion to the conventional technique. Concerning the remnant patients, the overall average costs were: for Operative Room, 1186,69 € for the MIVAP group (51 patients) and 836,11 € for the OMIP group (p<0,001); for the Team, 122,93 € (group A) and 90,02 € (group B) (p<0,001); the other operative costs were 1388,32 € (group A) and 928,23 € (group B) (p<0,001). The patient's satisfaction was very strongly in favour of the group B (Odds Ratio 20,5 with a 95% confidence interval). CONCLUSIONS: MIVAP is more expensive compared to the "open" parathyroidectomy under local anaesthesia due to the costs of general anaesthesia and the longer operative time. Moreover, the patients generally prefer the local anaesthesia. Nevertheless, the rate of conversion to the conventional parathyroidectomy was relevant in the group of the local anaesthesia compared to the MIVAP, since the latter allows a four-gland exploration.

Complication of endoscopic tattooing: a case report of covered perforation.

AIM: Laparoscopy is considered a good approach in treatment of colorectal neoplastic diseases; the endoscopic tattooing is then recommended (Evidence Level III and grade of recommendation A) to mark a lesion or a polypectomy site for intraoperative identification. We describe the case of perforation after tattoing treated conservatively. CASE REPORT: 63 years old woman, underwent colonoscopy for lipoma tattooing with India ink SPOT® solution kit and saline test. Immediately after the procedure the patient has been referred the appearance of colic epi-mesogastric pain and fever; Computed Tomography (CT) without MDC identified an irregular thickening of transverse colon with some microbubbles compatible with focal peritonitis. Initial paralytic ileus was present too. The blood count and metabolic panel examinations reveal a neutrophil leucocytosis (WBC: 11.000/mmc, 80% neutrophils). RESULTS: On the base of WSES sepsis severity score and recent literature patient was treated conservatively with total parenteral nutrition, and intravenous antibiotic therapy. After the resolution of fever and reactivation of peristalsis. The discharge occurred after six days with no early complications. CONCLUSION: India ink tattooing with SPOT® solution kit and saline test represent the first choice. It is a feasible technique although perforation is a possible complication. It may need an immediately surgical operation but in most cases a conservative management is a good and safe tool even if surgery may be attempted too.

Large retroperitoneal abscess extended to the inferior right limb secondary to a perforated ileal Crohn's disease: the importance of the multidisciplinary approach.

The typical complications of Crohn's disease concerns small and large bowel. The full thickness inflammation of the intestinal wall develops in strictures, fistulas and abdominal abscesses. Nowadays the most accepted therapeutic for intra-abdominal abscess option is antibiotic therapy and, in case of need, percutaneous drainage of the abscess. If the abscess passes through the pelvic foramen the abscess can involve the inferior limbs. We report a case a perforation of terminal ileum in Crohn's disease complicated by a large abscess of the right iliac fossa reaching the spaces between the anterior lateral muscles of the right thigh as far as the anterior lateral pre-tibial region. We discuss the diagnostic and therapeutic options in a multidisciplinary context.

Neuroendocrine tumor of the common bile duct: case report.

Neuroendocrine tumors (NET) are a very heterogeneous group of neoplasms; in recent years we have seen an increase in their incidence (3.65 /100.000/year). They can be associated with hereditary endocrine syndromes (MEN, Von Hippel Lindau); they can occur at any age and the incidence is slightly higher in men than women. The aetiology of the neuroendocrine tumors is unclear; in most cases, inflammation of the bile ducts may be the underlying cause and for this reason, the initial patient's evaluation should be focused on the different aspects concerning the oncological one and the possible sequelae of the biliary obstructions that can evolve in biliary sepsis. All neuroendocrine tumors have malignant potential. The most frequent sites of extrahepatic biliary NETs are the common hepatic duct and the distal common bile duct (19.2%), followed by the middle of the common bile duct (17.9%), the cystic duct (16.7%), and the proximal common bile duct (11.5%). We can divide them into: well-differentiated and poorly differentiated. Considering the clinical features, neuroendocrine tumors can be divided into functional and non-functional. As regards the staging, we distinguish localized, regional and metastatic tumors. Tumors derived from the bile duct are difficult to diagnose preoperatively, mainly because of its low incidence and difficult diagnostic process. However since cholangiocarcinomas account for about 80% of all primary biliary tumors, it is important to think about other options despite their low frequency when a patient presents with abnormal characteristics. The most sensitive immunohistochemical markers are expressing neuron-specific enolase, synaptophisin and chromogranin A. Liver function tests, alkaline phosphatase and bilirubin are often high. Sometimes an anemia can appear in the presence of a chronic disease or in patients with more advanced disease. It is known that the measurement of chromogranin A is useful for the preoperative diagnosis of neuroendocrine tumors. Chromogranin A is elevated in 90% of neuroendocrine tumors of the intestine, and the levels correlate with tumor burden and the possibility of recurrence and, therefore, chromogranin A can be an effective biological marker for preoperative diagnosis of neuroendocrine tumors. Bile endocrine tumors remain silent until metastasizing or growing into neighboring organs, because of its uncommon diagnosis in early stages due to its low incidence, absence of serum markers and lack of symptoms related to the hormonal pattern. Preoperative diagnosis of common bile duct carcinoma is extremely difficult, because it is foretold by non-specific symptoms that include pain or discomfort in the right upper quadrant level and weight loss. A 51- year-old woman presented a jaundice and severe bile duct dilatation. The enhanced CT scan showed a mass, approximately 15 mm in diameter, in the distal common biliary duct. The MRI and ERCP confirmed the mass. Cromogranin A value was negative. The diagnosis of well differentiated endocrine tumor of the biliary tract was done after its surgical resection was performed. The postoperative period was uneventful. Extrahepatic biliary NETs are rare, and extrahepatic bile ducts reportedly account for only 0.32% of primary NET sites. The prognosis for NET of the bile duct appears to be poor.

Effect of aeration and agitation on the protease production by Staphylococcus aureus mutant RC128 in a stirred tank bioreactor.

The modified rotating simplex method has been successfully used to determine the best combination of agitation rate and aeration rate for maximum production of extracellular proteases by Staphylococcus aureus mutant RC128, in a stirred tank bioreactor operated in a discontinuous way. This mutant has shown altered exoprotein production, specially enhanced protease production. Maximum production of proteases (15.28 UP/ml), measured using azocasein as a substrate, was obtained at exponential growth phase when the bioreactor was operated at 300 rpm and at 2 vvm with a volumetric oxygen transfer coefficient (K(L)a) of 175.75 h(-1). These conditions were found to be more suitable for protease production.

Field trials of a vaccine against bovine mastitis. 2. Evaluation in two commercial dairy herds.

A vaccine against bovine mastitis was developed. The vaccine was based on inactivated, highly encapsulated Staphylococcus aureus cells; a crude extract of Staph. aureus exopolysaccharides; and inactivated unencapsulated Staph. aureus and Streptococcus spp. cells. In this study, the vaccine was evaluated in 164 cows from two commercial dairies (A and B) during a 4-mo period. Two doses of the vaccine were administered subcutaneously to 82 cows in the brachiocephalicus muscle of the neck within a 4-wk interval. The results of this trial revealed significantly fewer intramammary infections caused by Staph. aureus at various levels of severity (clinical, subclinical, and latent) in cows that were vaccinated. The odds ratios of all types of intrammammary infections caused by Staph. aureus for dairies A and B, which were determined by a logistic model, were 1.84 and 1.89, respectively, for quarters of vaccinated cows and quarters of control cows. The colony counts for Staph. aureus in milk from infected quarters of vaccinated cows were significantly lower than those in milk from infected quarters of control cows. Also, the somatic cell counts per milliliter in milk from vaccinated cows were significantly decreased when the initial somatic cell count was < 500,000 cells/ml at the start of the trial. The vaccine had no observable effect on fat production in milk or on streptococcal infections.