Ceftazidime: Semisynthetic, broad-spectrum antibacterial derived from CEPHALORIDINE and used especially for Pseudomonas and other gram-negative infections in debilitated patients.Cephalosporins: A group of broad-spectrum antibiotics first isolated from the Mediterranean fungus ACREMONIUM. They contain the beta-lactam moiety thia-azabicyclo-octenecarboxylic acid also called 7-aminocephalosporanic acid.beta-Lactamases: Enzymes found in many bacteria which catalyze the hydrolysis of the amide bond in the beta-lactam ring. Well known antibiotics destroyed by these enzymes are penicillins and cephalosporins.Aztreonam: A monocyclic beta-lactam antibiotic originally isolated from Chromobacterium violaceum. It is resistant to beta-lactamases and is used in gram-negative infections, especially of the meninges, bladder, and kidneys. It may cause a superinfection with gram-positive organisms.Microbial Sensitivity Tests: Any tests that demonstrate the relative efficacy of different chemotherapeutic agents against specific microorganisms (i.e., bacteria, fungi, viruses).Anti-Bacterial Agents: Substances that reduce the growth or reproduction of BACTERIA.Pseudomonas aeruginosa: A species of gram-negative, aerobic, rod-shaped bacteria commonly isolated from clinical specimens (wound, burn, and urinary tract infections). It is also found widely distributed in soil and water. P. aeruginosa is a major agent of nosocomial infection.Cephalosporin Resistance: Non-susceptibility of an organism to the action of the cephalosporins.Cefotaxime: Semisynthetic broad-spectrum cephalosporin.Thienamycins: Beta-lactam antibiotics that differ from PENICILLINS in having the thiazolidine sulfur atom replaced by carbon, the sulfur then becoming the first atom in the side chain. They are unstable chemically, but have a very broad antibacterial spectrum. Thienamycin and its more stable derivatives are proposed for use in combinations with enzyme inhibitors.beta-Lactams: Four-membered cyclic AMIDES, best known for the PENICILLINS based on a bicyclo-thiazolidine, as well as the CEPHALOSPORINS based on a bicyclo-thiazine, and including monocyclic MONOBACTAMS. The BETA-LACTAMASES hydrolyze the beta lactam ring, accounting for BETA-LACTAM RESISTANCE of infective bacteria.Amikacin: A broad-spectrum antibiotic derived from KANAMYCIN. It is reno- and oto-toxic like the other aminoglycoside antibiotics.Imipenem: Semisynthetic thienamycin that has a wide spectrum of antibacterial activity against gram-negative and gram-positive aerobic and anaerobic bacteria, including many multiresistant strains. It is stable to beta-lactamases. Clinical studies have demonstrated high efficacy in the treatment of infections of various body systems. Its effectiveness is enhanced when it is administered in combination with CILASTATIN, a renal dipeptidase inhibitor.Monobactams: Monocyclic, bacterially produced or semisynthetic beta-lactam antibiotics. They lack the double ring construction of the traditional beta-lactam antibiotics and can be easily synthesized.Piperacillin: Semisynthetic, broad-spectrum, AMPICILLIN derived ureidopenicillin antibiotic proposed for PSEUDOMONAS infections. It is also used in combination with other antibiotics.Pseudomonas Infections: Infections with bacteria of the genus PSEUDOMONAS.Klebsiella pneumoniae: Gram-negative, non-motile, capsulated, gas-producing rods found widely in nature and associated with urinary and respiratory infections in humans.Gram-Negative Bacteria: Bacteria which lose crystal violet stain but are stained pink when treated by Gram's method.Penicillanic Acid: A building block of penicillin, devoid of significant antibacterial activity. (From Merck Index, 11th ed)Melioidosis: A disease of humans and animals that resembles GLANDERS. It is caused by BURKHOLDERIA PSEUDOMALLEI and may range from a dormant infection to a condition that causes multiple abscesses, pneumonia, and bacteremia.Cefoperazone: Semisynthetic broad-spectrum cephalosporin with a tetrazolyl moiety that is resistant to beta-lactamase. It has been proposed especially against Pseudomonas infections.Azabicyclo Compounds: Bicyclic bridged compounds that contain a nitrogen which has three bonds. The nomenclature indicates the number of atoms in each path around the rings, such as [2.2.2] for three equal length paths. Some members are TROPANES and BETA LACTAMS.beta-Lactam Resistance: Nonsusceptibility of bacteria to the action of the beta-lactam antibiotics. Mechanisms responsible for beta-lactam resistance may be degradation of antibiotics by BETA-LACTAMASES, failure of antibiotics to penetrate, or low-affinity binding of antibiotics to targets.Drug Resistance, Microbial: The ability of microorganisms, especially bacteria, to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).Enterobacteriaceae: A family of gram-negative, facultatively anaerobic, rod-shaped bacteria that do not form endospores. Its organisms are distributed worldwide with some being saprophytes and others being plant and animal parasites. Many species are of considerable economic importance due to their pathogenic effects on agriculture and livestock.Tobramycin: An aminoglycoside, broad-spectrum antibiotic produced by Streptomyces tenebrarius. It is effective against gram-negative bacteria, especially the PSEUDOMONAS species. It is a 10% component of the antibiotic complex, NEBRAMYCIN, produced by the same species.Burkholderia pseudomallei: A species of gram-negative, aerobic bacteria that causes MELIOIDOSIS. It has been isolated from soil and water in tropical regions, particularly Southeast Asia.Enterobacteriaceae Infections: Infections with bacteria of the family ENTEROBACTERIACEAE.Klebsiella Infections: Infections with bacteria of the genus KLEBSIELLA.Enterobacter cloacae: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria that occurs in water, sewage, soil, meat, hospital environments, and on the skin and in the intestinal tract of man and animals as a commensal.Bronchopneumonia: Inflammation of the lung parenchyma that is associated with BRONCHITIS, usually involving lobular areas from TERMINAL BRONCHIOLES to the PULMONARY ALVEOLI. The affected areas become filled with exudate that forms consolidated patches.Bacterial Infections: Infections by bacteria, general or unspecified.Clavulanic Acid: Clavulanic acid and its salts and esters. The acid is a suicide inhibitor of bacterial beta-lactamase enzymes from Streptomyces clavuligerus. Administered alone, it has only weak antibacterial activity against most organisms, but given in combination with other beta-lactam antibiotics it prevents antibiotic inactivation by microbial lactamase.Gram-Negative Bacterial Infections: Infections caused by bacteria that show up as pink (negative) when treated by the gram-staining method.Ciprofloxacin: A broad-spectrum antimicrobial carboxyfluoroquinoline.Moxalactam: Broad- spectrum beta-lactam antibiotic similar in structure to the CEPHALOSPORINS except for the substitution of an oxaazabicyclo moiety for the thiaazabicyclo moiety of certain CEPHALOSPORINS. It has been proposed especially for the meningitides because it passes the blood-brain barrier and for anaerobic infections.CephalosporinaseIsoelectric Focusing: Electrophoresis in which a pH gradient is established in a gel medium and proteins migrate until they reach the site (or focus) at which the pH is equal to their isoelectric point.Serum Bactericidal Test: Method of measuring the bactericidal activity contained in a patient's serum as a result of antimicrobial therapy. It is used to monitor the therapy in BACTERIAL ENDOCARDITIS; OSTEOMYELITIS and other serious bacterial infections. As commonly performed, the test is a variation of the broth dilution test. This test needs to be distinguished from testing of the naturally occurring BLOOD BACTERICIDAL ACTIVITY.Drug Therapy, Combination: Therapy with two or more separate preparations given for a combined effect.Agranulocytosis: A decrease in the number of GRANULOCYTES; (BASOPHILS; EOSINOPHILS; and NEUTROPHILS).Carbapenems: A group of beta-lactam antibiotics in which the sulfur atom in the thiazolidine ring of the penicillin molecule is replaced by a carbon atom. THIENAMYCINS are a subgroup of carbapenems which have a sulfur atom as the first constituent of the side chain.Bacteria: One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.Drug Resistance, Bacterial: The ability of bacteria to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).Ceftriaxone: A broad-spectrum cephalosporin antibiotic with a very long half-life and high penetrability to meninges, eyes and inner ears.Half-Life: The time it takes for a substance (drug, radioactive nuclide, or other) to lose half of its pharmacologic, physiologic, or radiologic activity.Lactams: Cyclic AMIDES formed from aminocarboxylic acids by the elimination of water. Lactims are the enol forms of lactams.Drug Resistance, Multiple, Bacterial: The ability of bacteria to resist or to become tolerant to several structurally and functionally distinct drugs simultaneously. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.Sulbactam: A beta-lactamase inhibitor with very weak antibacterial action. The compound prevents antibiotic destruction of beta-lactam antibiotics by inhibiting beta-lactamases, thus extending their spectrum activity. Combinations of sulbactam with beta-lactam antibiotics have been used successfully for the therapy of infections caused by organisms resistant to the antibiotic alone.Gram-Positive Bacteria: Bacteria which retain the crystal violet stain when treated by Gram's method.Fever: An abnormal elevation of body temperature, usually as a result of a pathologic process.Home Infusion Therapy: Use of any infusion therapy on an ambulatory, outpatient, or other non-institutionalized basis.Enterobacter: Gram-negative gas-producing rods found in feces of humans and other animals, sewage, soil, water, and dairy products.Endophthalmitis: Suppurative inflammation of the tissues of the internal structures of the eye frequently associated with an infection.Klebsiella: A genus of gram-negative, facultatively anaerobic, rod-shaped bacteria whose organisms arrange singly, in pairs, or short chains. This genus is commonly found in the intestinal tract and is an opportunistic pathogen that can give rise to bacteremia, pneumonia, urinary tract and several other types of human infection.Ticarcillin: An antibiotic derived from penicillin similar to CARBENICILLIN in action.Infusions, Intravenous: The long-term (minutes to hours) administration of a fluid into the vein through venipuncture, either by letting the fluid flow by gravity or by pumping it.Injections, Intravenous: Injections made into a vein for therapeutic or experimental purposes.Penicillins: A group of antibiotics that contain 6-aminopenicillanic acid with a side chain attached to the 6-amino group. The penicillin nucleus is the chief structural requirement for biological activity. The side-chain structure determines many of the antibacterial and pharmacological characteristics. (Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p1065)Gentamicins: A complex of closely related aminoglycosides obtained from MICROMONOSPORA purpurea and related species. They are broad-spectrum antibiotics, but may cause ear and kidney damage. They act to inhibit PROTEIN BIOSYNTHESIS.Drug Incompatibility: The quality of not being miscible with another given substance without a chemical change. One drug is not of suitable composition to be combined or mixed with another agent or substance. The incompatibility usually results in an undesirable reaction, including chemical alteration or destruction. (Dorland, 27th ed; Stedman, 25th ed)Cefsulodin: A pyridinium-substituted semisynthetic, broad-spectrum antibacterial used especially for Pseudomonas infections in debilitated patients.Cross Infection: Any infection which a patient contracts in a health-care institution.