When the T>MIC in the serum equates to 60 - 70% of the frequency for drug administration (dosing interval), maximal activity is achieved against Gram-negative bacteria, while for Gram-positive bacteria it occurs at around 40 - 50%.Within a 24-hour period in one clinical study, a T>MIC surpassing 60% was found for piperacillin-susceptible bacteria including Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus in two dosing regimes (4.5g every 8 hours and 3.375g every 8 hours).The evidence for this was obtained through Monte Carlo experiments procured by a special program (OPTAMA), where for several different scenarios (e.g. hospital acquired infections, secondary peritonitis, skin or soft tissue infections), the probability of attaining those figures were in the ranges of 85 - 95% and 90 - 89% respectively for the two regimes. In addition, two similar dosing regimes (3.375g and 4.5g every 6 hours) both had lower chances of reaching the 90% T>MIC threshold compared to the 50% threshold against hospital acquired pneumonia pathogens.The optimization of piperacillin-tazobactam drug efficiency has been covered by various studies, limiting the focus down to two types of infusions; continuous and intermittent. A comparison using the two administration methods under the same dosage regime of 13.5g per day highlighted no major differences when treating complex intra-abdominal infections. Furthermore, a follow-up analyzation of this trial deduced that both methods of administration lead to higher concentrations compared to the MIC of the pathogens that were used.
Bowel sound may be increased (borborygmi) due to excessive peristaltic action of the stomach. Fullness in the left hypochondrium may also be present. Causes
The causes are divided into benign or malignant. Benign
Peptic ulcer disease
Infections, such as tuberculosis; and infiltrative diseases, such as amyloidosis. A rare cause of gastric outlet obstruction is blockage with a gallstone, also termed "Bouveret syndrome" or "Bouverets syndrome". In children congenital pyloric stenosis / congenital hypertrophic pyloric stenosis may be a cause. A pancreatic pseudocyst can cause gastric compression. Pyloric mucosal diaphragm could be a rare cause. Malignant
Tumours of the stomach, including adenocarcinoma (and its linitis plastica variant), lymphoma, and gastrointestinal stromal tumours

Pathophysiology
In a peptic ulcer it is believed to be a result of edema and scarring of the ulcer, followed by healing and fibrosis, which leads to obstruction of the gastroduodenal junction (usually an ulcer in the first part of the duodenum). Diagnosis
The most confirmatory investigation is endoscopy of upper gastrointestinal tract. Laboratory often find hypochloremic, hypokalemic, and alkalotic due to loss of hydrogen chloride and potassium. High urea and creatinine levels may also be observed if the patient is dehydrated. Abdominal X-ray may show a gastric fluid level which would support the diagnosis. Barium meal and follow through may show an enlarged stomach and pyloroduodenal stenosis.Gastroscopy may help with cause and can be used therapeutically. Differential diagnosis
The differential diagnosis of gastric outlet obstruction may include: early gastric carcinoma, hiatal hernia, gastroesophageal reflux, adrenal insufficiency, and inborn errors of metabolism.