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Enterococci are rarely implicated in the causation of pneumonia or lung abscess. Two patients are reported who developed large lung abscess cavities from enterococcal pneumonia. Combination penicillin and aminoglycoside antimicrobial therapy and drainage with a transthoracic tube resulted in complete cavity closure and healing. Enterococci should be considered as possible etiologic agents of pneumonia. Percutaneous chest tube drainage appears helpful in certain types of lung abscess.

4'-Deoxykanamycin A (12) has been prepared by two different routes (Routes A and B) starting from 6'-N-benzyloxycarbonyl-kanamycin A (1) which was prepared by the selective benzyloxycarbonylation of kanamycin A. The key compounds for the 4'-deoxygenation, N, O-poly-blocked derivatives having a free hydroxy group on C-4', were prepared either by the cleavage of the 4', 6'-cyclic carbamate (7) to the 6'-N-carbethoxy derivative (8) in Route A or by the O→N migration of an acetyl group from the 4'-hydroxy group to the 6'-amino group (13→44) in Route B, 4'-Deoxykanamycin A is significantly more active than kanamycin against Pseudomonas strains and also inhibits the resistant organisms which produce neomycin-kanamycin phosphotransferase II.

An improved enzymatic assay has been developed for the rapid quantitative measurement of gentamicin or tobramycin in serum and other biological fluids. The assay uses a crude enzyme from Escherichia coli W677/HJR66 that adenylates gentamicin or tobramycin in the presence of adenosine-5'-triphosphate (ATP). Enzymatic adenylation of gentamicin is optimal at 8 mM Mg2+, and the Michaelis constant (K,,) of the enzyme for ATP is 0.043 mM. The modifications introduced here increase the sensitivity and decrease the background radioactivity of the previously described assay. The amount of 14C-ATP required per assay is also reduced, thereby decreasing the cost of the assay. The accuracy of the present method has been demonstrated both in control experiments and with 96 specimens of serum from 59 patients treated with gentamicin. Ten other commonly used antibiotics structurally unrelated to aminoglycosides were tested and do not interfere with the assay. The present method is not suitable for kanamycin assays because the crude enzyme used contains activities that catalyze two different ATP-dependent reactions leading to phosphorylation or adenylation of kanamycin.

The in vitro activity of seven anti-staphylococcal antibiotics alone and in combination with four aminoglycoside antibiotics against 35 clinical isolates of Staphylococcus aureus from blood cultures of patients with endocarditis or septicemia was studied. The combination of nafcillin-gentamicin or nafcillin-tobramycin when compared with nafcillin alone killed significantly more S. aureus at 6 h for 33 of 35 isolates. A significant decrease in viable colony-forming units at 24 and 48 h was demonstrated for a smaller number of isolates. Using the agar dilution antibiotic susceptibility test, significant enhancement of activity was demonstrated against almost all isolates when cephalothin, cefazolin, or clindamycin was combined with gentamicin, tobramycin, or kanamycin. The combination of nafcillin or vancomycin with gentamicin, tobramycin, or kanamycin also showed enhanced activity against the majority of isolates. Oxacillin or methicillin when combined with the aminoglycosides showed enhancement of activity against the least number of isolates. Streptomycin was the least effective of the four aminoglycoside antibiotics studied.

The presence of aminoglycoside antibiotics interferes with the determination of clindamycin levels by standard microbiological assay. A new bioassay method of quantitation of clindamycin in the presence of aminoglycosides is presented. This technique is based on the fact that incorporation of calcium chloride into assay agar blocks the antimicrobial activity of aminoglycosides against Sarcina lutea but allows the assay of as little as 0.31 μg of clindamycin per ml. The error of the system is less than 10%. This method is simple and adaptable to existing assay systems for clindamycin.

One hundred fifty-two bacterial strains that possess resistance to kanamycin A, gentamicin, or tobramycin, or to more than one of these antibiotics, were collected from various sources in Canada, Europe, Japan, and the United States. This collection was composed of Staphylococcus aureus and Pseudomonas aeruginosa and members of the Enterobacteriaceae family. Their susceptibility to BB-K8 (amikacin), a new broad-spectrum semisynthetic derivative of kanamycin A, and to the other agents, was determined on Mueller-Hinton Medium by the twofold agar dilution method. Test results revealed that 60.5% of the isolates were resistant to 8 μg of tobramycin per ml, 67.1% to 8 μg of gentamicin per ml, 86.2% to 20 μg of kanamycin A per ml, and only 8.6% to 20 μg of amikacin per ml. Of interest is the fact that the amikacin-resistant strains were generally resistant to all of the other aminoglycosides. The broad spectrum of amikacin was not totally unexpected, because the compound has been shown to be a poor substrate for most enzymes that inactivate other aminoglycosides through O -phosphorylation, O -adenylylation, or N -acetylation. A number of susceptibility profiles were obtained when the organisms were tested against a series of nine aminoglycosides. The majority of these profiles resembled those found for organisms that possess known mechanisms of enzymatic inactivation.

Therapy of bivalvular Pseudomonas aeruginosa endocarditis in a narcotics user is described. Measurement of serum levels of tobramycin, the aminoglycoside antibiotic used, was essential to determine adequate dosage levels. Clinical and therapeutic data in 29 previously reported cases of Ps. aeruginosa endocarditis are summarized. The acute nature of this disease and the effect of modern medical and surgical therapy upon its course are discussed. Intravenous narcotics use is a frequent predisposing factor in the development of Pseudomonas endocarditis. Clinical symptoms and signs of meningitis occurred in more than one third of the patients with left-sided endocarditis.

The structures of Bu-1975C1 and C2 have been determined to be 4'-deoxybutirosins A and B. They contain the new deoxyaminosugar, 2, 6-diamino-2, 4, 6-trideoxy-α-D-xylo-hexopyranose (4-deoxyneosamine C).

Procedures routinely in use in many hospital microbiology laboratories do not distinguish between enterococci and nonenterococcal Group D streptococci. During a 15-month period we observed 11 patients with bacterial endocarditis due to Group D streptococci, eight of which were due to the nonenterococcal species, Streptococcus bovis. This micro-organism showed in vitro susceptibility to a wide variety of antimicrobial agents, including oxacillin and lincomycin. In patients with S. bovis infection, high serum bacteriostatic and bactericidal levels were achieved with penicillin or clindamycin alone, or penicillin and an aminoglycoside. The clinical response was equivalent with all drug regimens. In contrast, enterococci were more resistant in vitro to antibiotics, and in vivo definitely lower serum bactericidal activity was achieved. Infections due to S. bovis are probably often misdiagnosed. It is of clinical importance to distinguish S. bovis from the enterococci because therapy for the former spe...

Antibiotic G-418 is a new aminoglycoside produced as the major component by a new species of Micromonospora, M. rhodorangea NRRL 5326. The antibiotic is prepared by submerged fermentation in a soybean-dextrin medium. Antibiotic G-418 is adsorbed on a cationic-exchange resin and separated from other impurities by passing it down a Dowex (1 × 2) resin column. The antibiotic, which contains 2-deoxystreptamine, has broad-spectrum antibacterial activity and is highly active against protozoa, amoebae, tapeworm, and pinworm infections in mice. This report describes the taxonomy of the organism, and fermentation, isolation, and preliminary characterization of antibiotic G-418.

A new R factor-mediated gentamicin acetyltransferase obtained from a clinical isolate of gentamicin-, tobramycin-, and kanamycin-resistant Klebsiella was characterized. R factor R 176 was transferred to Escherichia coli K-12 LA 290 from a Klebsiella . Resistance transfer, minimal inhibitory concentrations of various aminoglycoside antibiotics, enzymatic inactivation, and the isoelectric point of the enzyme obtained were determined. We found that R factor R 176 could govern the enzymatic 3-N acetylation of gentamicin, tobramycin, and kanamycin, and isoelectric point determinations suggested that the enzymes governed by R 176 and R 135 are different. The genes responsible for resistance to gentamicin, tobramycin, and kanamycin govern the synthesis of an isoenzyme of AAC(3)I, which we propose to call AAC(3)II.

Following the development of chemotheraphy, the increase of drug-resistant bacteria has been very important problem. A new aminoglycoside antibiotic, lividomycin (LVM) showed widely antibacterial activity, but LVM-resistant bacteria were found in clincal isolates before clinical trial of the drug. We investigated LVM-resistant mechanisms in bacteria and following results were obtained.1) Many LVM-resistant strains showed also resistance to Kanamycin (KM). Therefore, there ara three types with regard to resistant patterns between KM and LVM, ie., I (KMr, LVMr), II (KMr, LVMs) and III (KM-As, LVMr).2) LVM-resistant mechanism in type I strains was due to LVM-inactivating enzyme capable of phosphorylating OH group of ribose moiety of LVM.3) LVM-resistant mechnism in type III bacteria was caused to inactivating enzyme capable of acetylating 2'-NH2 of LVM and this enzme inactivated all aminoglycosides containing 2'-amino group.4) In vitro-developed LVM-resistant strain of E. coli affected no inactivating enzyme and LVM-resistance of this strain would be due to the decrease of permeability of the drug.

Forty-one strains of Streptococcus mutans (34 from blood specimens from patients with endocarditis and 7 from stock cultures) were tested for susceptibility to penicillin, ampicillin, methicillin, erythromycin, cephalothin, vancomycin, chloramphenicol, tetracycline, gentamicin, streptomycin, and kanamycin. Minimal inhibitory and bactericidal concentrations were determined by a broth microdilution procedure. Most of the strains were very susceptible to ampicillin, penicillin, and erythromycin, with most strains having minimal inhibitory concentrations of 0.08 μg/ml or less. Most of the strains were also susceptible to cephalothin, methicillin, chloramphenicol, tetracycline, and vancomycin. Gentamicin was the most effective aminoglycoside. The antimicrobial susceptibility patterns are similar to those of other viridans streptococci. S. mutans strains have proven to be difficult for some microbiologists to identify. But when organisms suggesting S. mutans are isolated from patients with endocarditis, they should be at least identified as nonenterococcal streptococci so that appropriate therapy can be initiated.

Seventy-four strains of Streptococcus bovis and 35 strains of enterococci ( Streptococcus faecalis and its varieties, Streptococcus faecium and Streptococcus durans ), most of which were isolated from patients with endocarditis, were tested for their susceptibility to penicillin, ampicillin, erythromycin, cephalothin, vancomycin, methicillin, tetracycline, chloramphenicol, kanamycin, streptomycin, and gentamicin. Minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) were determined by a microtiter broth dilution technique. All of these organisms are group D streptococci, but the S. bovis strains are not enterococci. On the basis of both MIC and MBC, the S. bovis strains were much more susceptibile in general to antibiotics then were the enterococcal strains. For the S. bovis strains, the lowest MICs were obtained with penicillin, ampicillin, and erythromycin, and the lowest MBCs with penicillin and ampicillin. Although these antibiotics were also the most active against the enterococci, the MICs and MBCs were much higher than obtained with the S. bovis strains. Gentamicin was the most active aminoglycoside. On the basis of in vitro susceptibility results, the S. bovis strains resemble the viridans streptococci rather than enterococci.

The in vitro effects of the aminoglycoside antibiotics tobramycin and gentamicin were compared, chiefly against Pseudomonas aeruginosa but also against Staphylococcus aureus and Proteus species. These antibiotics did not differ greatly in effectiveness. Studies with the electron microscope showed that short exposure to tobramycin altered the morphologic appearance of the bacterial cell.

A new aminoglycoside antibiotic was isolated from the fermentation broths of two strains of Bacillus species. The antibiotic is active against gram-positive and some gram-negative bacteria, and its antimicrobial spectrum is similar to that of ribostamycin. The chemical structure was determined to be 5-β- d -xylofuranosylneamine, which is identical to the deacylated product obtained from butirosin A.

The new aminoglycoside antibiotic, amikacin (formerly called BB-K8), was used to treat 12 episodes of urinary tract infection caused by hospital-acquired Proteus rettgeri strains. These bacteria were resistant in vitro to kanamycin and gentamicin, and infection persisted in most of the patients in spite of therapy with one of these agents. In all cases, the urinary tract infection was controlled or eradicated by therapy, although relapse or reinfection was frequently encountered in these patients with complicated urological problems. No toxicities attributable to the drug were encountered in the small group of patients.

Tobramycin, a new aminoglycoside antimicrobial, was evaluated as therapy for infections due to gram-negative bacilli in 15 seriously ill patients with underlying diseases. Three of 10 patients with gram-negative bacteremias also had urinary tract infections. Two patients had respiratory tract infections, one had cellulitis, one had a urinary tract infection, and another had septic phlebitis. Twelve patients were cured of their infections. Eosinophilia was observed in one patient and another developed superinfection with Staphylococcus aureus after 6 days of tobramycin therapy. There were five isolates of Escherichia coli , five of Klebsiella sp., two of Pseudomonas sp., and one each of Enterobacter agglomerans, Serratia marcescens , and Enterobacter cloacae . The average serum concentration of tobramycin 2 h after a parenteral dose of 1.0 to 1.5 mg/kg was 5.1 μg/ml; higher concentrations of tobramycin were present in urine. Tobramycin proved to be an effective antimicrobial in these patients.

The effect of gentamicin against 130 clinical isolates of Pseudomonas aeruginosa was compared with that of two investigational aminoglycoside antibiotics, tobramycin and amikacin. Minimal inhibitory concentration data indicated that, on a weight basis, tobramycin was two to four times as active as gentamicin against most isolates. However, 14 of 18 organisms highly resistant to gentamicin (≥80 μg/ml) were also highly resistant to tobramycin. Amikacin was the least active aminoglycoside on a weight basis, but none of the isolates were highly resistant to this antibiotic. When therapeutically achievable concentrations were used, adding carbenicillin to gentamicin or to tobramycin enhanced inhibitory activity against those isolates susceptible (≤5 μg/ml) or moderately resistant (10 to 40 μg/ml) to the aminoglycoside. Such synergy was seldom demonstrated for isolates highly resistant to gentamicin or tobramycin. The combination of carbenicillin and amikacin enhanced inhibition against all but two of the isolates. Both tobramycin and amikacin offer in vitro advantages over gentamicin against P. aeruginosa .

Experiments were conducted to examine the effects of certain aminoglycoside antibiotics on contractile responses and related calcium ion (Ca 2+ ) movements in isolated vascular smooth muscle. Gentamicin, kanamycin, and streptomycin decreased contractile responses produced by norepinephrine, histamine, and high K + in rabbit aortic strips. The inhibitory action of these antibiotics on mechanical function was more pronounced when the Ca 2+ concentration of the bathing solution was decreased from 1.5 mM (normal Ca 2+ solution) to 0.05 mM (low Ca 2+ solution). The uptake of radiocalcium ( 45 Ca) into the isolated media-intimal layer of rabbit aortae was decreased in a maintained manner by each antibiotic. With gentamicin, the inhibitory effect on 45 Ca uptake was shown to be dependent upon the concentration of gentamicin employed and to be more evident in a 0.1 mM Ca 2+ solution than in a normal Ca 2+ solution. In addition, the rate of 45 Ca efflux from the rabbit aortic media-intimal layer was increased in a sustained manner by gentamicin, streptomycin, and kanamycin. Furthermore, contractile responses induced by high K + and norepinephrine in canine carotid arterial strips were inhibited by gentamicin. Present findings indicate that aminoglycoside antibiotics interfere with Ca 2+ -linked events leading to activation of the contractile mechanism of vascular smooth muscle. These in vitro findings may partially explain the occurrence of in vivo cardiovascular depression that has occasionally been observed after the administration of chemically related antimicrobial agents.

Among gram-negative bacilli isolated from burn wound cultures, some strains of Enterobacteriaceae were resistant to tobramycin (minimal inhibitory concentration [MIC]≥ 20 μg/ml) but susceptible to gentamicin (MIC ≤ 5 μg/ml). One Klebsiella pneumoniae and two Enterobacter cloacae strains were selected for studies on their mechanisms of resistance to aminoglycoside antibiotics. Resistance to high concentrations of tobramycin (MICs of 25 to 50 μg/ml) was conjugally transferred to a susceptible Escherichia coli strain at rates of 1.2 × 10 −4 to 2.8 to 10 −4 per donor cell, suggesting that resistance is controlled by R factors. Resistances to tobramycin, kanamycin, and neomycin were cotransferred. Enzymatic activities were present that acetylated tobramycin, gentamicin, and kanamycin in osmotic lysates from the donor and transcipient strains. Enzymatic adenylylation of these aminoglycosides was not observed. The aminoglycoside-acetylating activities from K. pneumoniae and E. cloacae resembled kanamycin acetyltransferase (KAT) in their specificity for aminoglycoside substrates. Not all isolates of bacteria that produce KAT are resistant to tobramycin, but the factors that determine susceptibility or resistance to tobramycin in KAT-producing bacteria have not yet been established.

The half-life of gentamicin, tobramycin, kanamycin, and streptomycin, after a single subcutaneous injection, was measured in homogenates of lung, liver, and kidney in rats, and the results were compared with the half-life of these drugs in serum. Urinary excretion of antibiotics was also monitored. The half-life of the four drugs in serum and lung was approximately 30-35 min. Concentrations in the liver were regularly lower than concentrations in serum or lung. In renal tissue, gentamicin, tobramycin, and kanamycin had long half-lives of 109, 74, and 60 hr, respectively. Streptomycin, on the other hand, had a half-life of 4.6 hr. Separation of the kidneys into cortex and medulla showed that streptomycin was uniformly distributed, whereas 85% of the gentamicin, tobramycin, and kanamycin resided in the cortex. These antibiotics accumulate in the renal cortex, probably intracellularly, and have long half-lives.

tide substrate with a Km of 61 tM; however, 2'-deoxy ATP, guanosine-5'-triphosphate, uridine-5'-triphosphate, and cytidine-5'-triphosphate can also be used. Data were obtained that suggested the products of the reaction are gentamicin adenine mononucleotide and pyrophosphate. GAT was used to measure concentrations of gentamicin in serum, urine, and bile. In these fluids, quantitation of added gentamicin gave values within 10% of theoretical. Correlation of the enzymatic assay of gentamicin in serum was excellent with the 18-hr microbiologic method (r = 0.952), as well as with the more rapid microbiologic technique (r = 0.934). Similar correlation coefficients were obtained when urine was examined. GAT appears to offer a rapid, specific, and sensitive means of quantitating gentamicin and certain other aminoglycoside antibiotics in body fluids.

Summary Serum and milk concentrations of gentamicin, kananiycin, neomycin and paro-momycin were determined in lactating ewes after intravenous treatment (20 mg/kg) and duringequilibrium, and following intramuscular injection (10 mg/kg) to cows and ewes. After a singleintravenous injection, the half-life values in serum ranged from 1.85 h for gentamicin to 4.65 h for paromomycin. The drugs were calculated to occupy less than 20% of total body volume and onlya very small traction oj the dose was recovered in milk secreted from normal or irritated glandsduring the 12 h after treatment. At equilibrium the milk to serum ultrafiltrate concentration ratios were less titan the calculatedtheoretical ratios expected had penetration into milk been by passive diffusion. It is suggested thatthe limited penetration of these drugs into milk was mainly due to their poor lipid solubilitycharacteristics, which would curtail their potential usefulness in the parenteral treatment of mastitis.

Summary Moraxella strains isolated in clinical situation and resistant to aminoglycoside antibiotics, have been shown to contain an enzyme which acetylates the 6′-amino group of the aminohexose ring of kanamycin, BBK 8, tobramycin and related antibiotics. This enzyme is an isoenzyme of kanamycin acetyltransferase.

The microbiological characteristics of Streptomyces strain No. 7906 include formation of white aerial mycelium, light brown growth and thick aerial hyphae forming tufts. Strain No. 7906 was compared with known species and identified as a new species and given the name Streptomyces tateyamensis. Streptomyces tateyamensis No. 7906 produces new sulfur-containing peptide antibiotics which are named thiopeptins. The major component, thiopeptin B, is obtained as a crystalline powder decomposing at 219-222°C, and exhibiting optical rotation [a]23D -80°(c 1, chloroform). Its elementary analysis suggested the empirical formula C72H90O22N18S6. The ultraviolet absorption maxima (shoulder) were found at 230-250, 295 and 305 mμ. Thiopeptin B showed strong antibacterial activity against Gram-positive bacteria and had no cross resistance with penicillins, aminoglycoside antibiotics, tetracyclines and macrolides. The administration of 500 mg/kg of this antibiotic into mice by intraperitoneal route did not result in any toxic symptom.

Gale, Glen R. (Veterans Administration Hospital, Durham, N.C.). Urease activity and antibiotic sensitivity of bacteria. J. Bacteriol. 91: 499–506. 1966.—An investigation was made of the responses of certain urease-positive bacteria to various antibacterial drugs in the presence of highly specific urease inhibitors, in a test of the hypothesis proposed by other workers that inhibition of bacterial urease enhances the sensitivity of the cells to antimicrobial agents. Urease inhibitors employed were seven hydroxamic acids (HA). Six of the seven HA reduced the sensitivity of nine Proteus strains to ampicillin and methenamine mandelate. Two HA increased the sensitivity to colistin, and six HA increased the sensitivity to kanamycin. Investigation of the mechanism of action of the synergistic effect between kanamycin and HA led to the tentative conclusion that potentiation was mediated through an initial alteration of cell permeability by the aminoglycoside antibiotic which permitted accumulation of each of the six HA into the cell, at which point each interacted with pyridoxal phosphate. The single HA which failed to yield synergism with kanamycin failed to interact with pyridoxal phosphate in a nonenzymatic system; the other six HA produced alterations of the normal ultraviolet absorption spectrum of the coenzyme.

The biological activity of aminoglycoside antibiotics can be demonstrated simply in cell-free extracts in I of 2 ways: (1) inhibition of natural messenger RNA-directed protein synthesis, (2) misreading (stimulation of ambiguous translation) of synthetic polymer-directed polypeptide synthesis. These 2 effects, which do not seem to be directly related (it is possible to demonstrate inhibition without misreading) are convenient ways of comparing the efficacity of various aminoglycosides. The levels of misreading prodtfced by various antibiotics are markedly dependent on the drug concentration, and each antibiotic gives a curve with a characteristic shape [1]. These concentration-activity curves correlate reasonably well with the in vivo activity of the drugs. Since any structural modification which affects drug activity in this system is reflected in changes in the shape of the curves, this type of experiment provides us with a very sensitive assay for structure-activity relationships, thus eliminating many of the problems of such studies in vivo (altered permeability of the drug, for example). Conclusions concerning the structural requirements for misreading activity have been reported recently [2], and we summarize here results of our studies on the activity of certain structurally modified aminoglycosides. 1. Streptomycin group. Very little structural modification without substantial loss of activity is possible in this group. The modifications which cause little or no change in activity are (a) reduction of the aldehyde to a primary alcohol (dihydrostreptomycin), (b) linkage of a mannose residue to the 4'-OH of the N-methylL-glucosamine residue (mannisidostreptomycin), or (c) removal of 1 amidino residue (bluensomycin). Substantial loss of activity is accompanied by removal of both amidino residues, blocking of the 3-OH' on the N-methyl-L-glucosamine residue, or by attachment of alkyl side chains through the aldehyde moiety. None of the hydrolysis products of streptomycin have any antibiotic activity. 2. Neomycin group. Although few structurally modified neomycins are available, a convenient sequential series of degradation products has been tested, and neomycin is substantially more active as an antibiotic than neamine, while the other part of the molecule, methyl neobiosaminide, is inactive. On the other hand, paromomycin, which can be considered a hydroxydesamino derivative of neomycin, is less active than neomycin, and its degradation product paromamine (a hydroxydesamino neamine) is inactive both as an antibiotic and in cell-free systems. The replacement of a primary hydroxyl group by an amino group has, in this case, drastic conse

It has repeatedly been observed that the results of sensitivity testing for gentamicin are influenced by both the pH of the medium and the size of the inoculum. In other reports the pH of the medium i

Tobramycin is an aminoglycoside antibiotic which has excellent antibacterial activity against Pseudomonas, Staphylococcus aureus , and many members of the Enterobacteriaceae . Most strains of Serratia, Providence, Streptococcus , and Diplococcus pneumoniae were resistant to concentrations of tobramycin which could be achieved in man. Tobramycin was effective against certain Pseudomonas strains resistant to gentamicin. The growth medium used to determine the inhibitory level of tobramycin had a significant effect upon the minimal inhibitory concentration. Calcium and magnesium ions inhibited the bactericidal effect of tobramycin. Tobramycin and carbenicillin acted in a synergistic manner. Ethylenediaminetetraacetic acid did not act in a synergistic manner with tobramycin. Broth-dilution susceptibility tests and disc-diffusion tests in agar (10-μg discs) showed excellent correlation except with Proteus strains.

Gastrointestinal flora was investigated by means of puncture method of alimentary tract during laparotomy of patients with benign and malignant diseases, and also during autopsy of accidental and diseased cadavers. Bacterial study of anal region was also carriedout in healthy adults and patients with anal diseases by means of direct culture.Most frequently detected microbes in the transverse colon and in the sigmoid colon were E. coli and Bacteroides, and anal flora of healthy adults was similar to those of the colon.Bacterial flora of the colon were not influenced by gastric acidity or cancer of the stomach.Aerobic microbes decreased their detection rate after three days successful oral administration of Neomycin or Kanamycin, and reincreased after five days use. However, anaerobic microbes increased their detection rate after three days oral administration of Neomycin and decreased after four to six days use.Aerobic microbes such as E. coli, Proteus, Klebsiella and Pseudomonas which were detected from subjects after five days administration of such antibiotics showed high resistence to some kinds of drugs.Therefore, preoperative oral administration of aminoglycoside antibiotics for three days limitted period was considered to be effective as an intestinal antisepsis against aerobic microbes, but was not so effective against anaerobic flora.

Tobramycin, an aminoglycoside antibiotic, has been administered to mice, rats, cats and dogs for toxicologic evaluation. The sc LD50 values in mice and rats were 441 and 969 mg/kg, respectively. Deaths were preceded by CNS depression and occurred within 1 hr of treatment. A 100 mg/kg iv dose in chloralose-anesthetized cats produced a moderate, transient decrease in blood pressure and a significant decrease in inspiratory volume and soleus twitch force. Rats were given daily sc doses of 15–120 mg/kg for 3 months. Renal tissue change, the only drug effect evident histologically, ranged in degree from a slight reparative nephrosis at the lowest dose to cortical tubular necrosis in some rats that received the highest dose. In a 1-month study, a daily im dose of 7.5 mg/kg had no apparent effect on dogs, but a 30 mg/kg dose produced severe renal damage. Vestibular injury occurred within less than 30 days in all cats that received daily sc doses of 50 mg/kg, but no vestibular changes were observed in cats that were given 65 doses of 25 mg/kg. The toxicologic effects observed in tobramycin-treated animals were qualitatively and quantitatively similar to those observed with gentamicin.

Ototoxicity of lividomycin (LVM), recently developed aminoglycoside antibiotic, was functionally as well as histopathologically evaluated in guinea pigs of Hartley strain (300g body weight at the start of the experiment). Sixty three guinea pigs were divided into following 5 groups.Group 1 (10 guinea pigs), each animal received LVM intramuscularly at dosis of 100mg/kg body weight.Group 2 (21 guinea pigs), each received LVM intramuscularly at dosis of 200mg/kg.Group 3 (11 guinea pigs), each received LVM intramuscularly at dosis of 400mg/kg.Group 4 (10 guinea pigs), each received KM intramuscularly at dosis of 100mg/kg.Group 5 (11 guinea pigs), each received KM intramuscularly at dosis of 200mg/kg.The antibiotics were given to the animals for 4 weeks. Pinna reflex test was performed before, during and after the experiment with audiometer. Frequencies of the audiometer ranged from 10, 000Hz to 500Hz. The animals underwent vital fixation with Wittmaack's fixative under general anesthesia after the end of the experiment. The temporal bones were en bloc removed from the skull and further fixed in the same fixative for one week. The temporal bones were embeded in celloidin after decalcification. The horizontally sectioned serial celloidin sections were stained with hematoxylin-eosin. Histopathological examination was performed on the spiral organ of the cochlea and the vestibular organ, with special reference to the extent of hair cell damage in the cochlea. The results obtained were as follows:1) LVM was ototoxic in guinea pigs at the dosis of 200 and 400mg per kg body weight. The ototoxicity was much prominent in the hair cells of the spiral organ. In the basal turn of the cochlea the outer hair cells were more sensitive to the antibiotic than the inner hair cells, but in the apical and 4th turns the inner hair cells were more vulnerable than the outer ones. The loss of the outer hair cells, that is advanced damage, started from the basal end and indicated a general tendency to spread upwards.2) LVM showed almost the same ototoxicity as KM at the dosis of 200mg/kg body weight in guinea pigs.

Engstrom and Kohonen 1965, Kohonen 1965, Engstrom 1967 established the general tendency in the pattern of outer hair cell and inner hair cell loss, in the ototoxicosis due to antibiotics by the application of surface specimen technique of the spiral organ. The general tendency is considered as very important for understanding the fundamental pathologic change of the spiral organ due to various kind of antibiotics on the one hand and for the evaluation of ototoxicity due to newly developed antibiotics on the other hand.The present authors intended to reevaluate the general tendency in the pattern of outer hair cell and inner hair cell loss of the spiral organ in the ototoxicosis due to antibiotics by the observation of the horizontally sectioned serial celloidin sections of the cochleas in 140 Hartley guinea pigs received various kinds of antibiotics. The antibiotics used in the present study were divided into 3 groups, that is, aminoglycoside antibiotics (Aminodeoxykanamycin, Aminosidine, Dihydrostreptomycin, Gentamicin, Lividomycin, Kanamycin A and Vistamicin), polypeptide antibiotics (Capreomycin, Enduracidin, Tuberactinomycin and Viomycin), and Rifampicin (Rifamycin). The results obtained were as follows:1) In the present study, hair cell loss of the spiral organ occurred in 62% (87 guinea pigs).2) Outer hair cell loss was found in 100% of the 87 guinea pigs and the pattern of the outer hair cell loss showed the general tendency similar to the tendency reported by Engstrom et al.; that is, loss of the outer hair cell almost always started at the basal end of the spiral organ and then spread upwards.3) Inner hair cell loss occured in 22% (20 guinea pigs) and was always associated with the loss of the outer hair cell. The damage frequently occurred in the apical and 4th turns.4) There was distinct difference in sensitivity to ototoxic antibiotics between the outer hair cell and the inner hair cell. The outer hair cells were more sensitive in the basal and 2nd turns, while the inner hair, cell was more sensitive in the apical and 4th turns.5) There was some difference in the pattern of the hair cell loss between the animals received the aminoglycoside antibiotics and those treated with the polypeptide antibiotics. In the animals received the aminoglycoside antibiotics the loss of the outer hair cell alone occurred more frequently than in the animals received the polypeptide antibiotics. On the contrary, the inner hair cell loss was found more frequently in the animals treated with the polypeptide antibiotics.6) Detection of the loss of the outer hair cell confined to the basal end of the spiral organ is very important in the evaluation of the ototoxicity of the newly developed antibiotics.

BB-K 8, a new semisynthetic aminoglycosidic antibiotic, was evaluated for ototoxicity, nephrotoxicity and neuromuscular blocking activity in the cat. As a reference, kanamycin was tested by the same experimental methods. Employing equivalent doses in terms of the free base and 7 days of intraperitoneal treatment, BB-K 8 and kanamycin were found to be similarly ototoxic and nephrotoxic. Acutely, both compounds also demonstrated a similar neuromuscular blocking activity after large intravenous doses.

Gentamicin, isolated in 1963 [1], has been shown to be an effective chemotherapeutic agent for a variety of infectious disease processes. Several studies [2, 3] have indicated the efficacy of gentamicin for urinary tract infections. In concentrations easily attainable in the serum and far exceeded in the urine, a bactericidal effect has been demonstrated against all Enterobacteriaceae, Pseudomonas, and penicillinase-producing as well as nonpenicillinase-producing staphylococci. Our work with gentamicin, some of which has been reported previously [4], was initiated in 1964 and is based on the treatment of more than

In the course of our search for new antibiotics, a strain of Bacillus circulans No. YQW-B6 was isolated from a soil sample collected in Taiwan. This organism produced a complex of aminoglycoside antibiotics designated Bu-1709, and the two major components, A1 and A2, were identified as butirosins A (I) and B (II)2-4), respectively. This paper reports the bioactive degradation products from butirosins and the semi-synthesis of butirosin analogs.

Aminoglycoside antibiotics were found to vary widely in the effect of variation in their concentration on the degree of misreading of synthetic RNA messengers. Thus, neomycin, kanamycin, and gentamicin showed a 3- to 5-fold increase in the level of misreading as the drug concentration was raised from 10−6 to 10−4M. This effect suggests that each of these drugs may act on more than one site. Observed changes in the qualitative nature of the misreading at different concentrations support this inference, which is also consistent with the absence of one-step mutants with high level resistance to these drugs. In contrast, little increase in misreading, over the same concentration range, was seen with streptomycin and paromomycin, for which one-step, high level, resistant mutants are known. It therefore seems that these drugs each act on only a single site.

The mechanism by which agents that inhibit bacterial cell wall synthesis produce a synergistic effect against enterococci when combined with aminoglycoside antibiotics has not been elucidated. Using 14C-labeled streptomycin, it could be shown that uptake of this aminoglycoside antibiotic was markedly enhanced in enterococci growing in the presence of penicillin or other agents which inhibit the synthesis of bacterial cell walls. There was no enhancement of streptomycin uptake when the cells were incubated with antibiotics which primarily affect the bacterial cell membrane or inhibit protein synthesis. Increased streptomycin uptake was produced by penicillin only in actively growing bacteria. These observations are consistent with the hypothesis that enterococci exhibit a natural barrier to the entry of streptomycin which can be overcome by agents which inhibit cell wall synthesis, thus producing a synergistic effect.

Three antimicrobial agents were evaluated as to their ability to neutralize the toxic effects of endotoxin in rabbits. These consisted of two cyclic polypeptides, polymyxin B sulfate and colymycin M (sodium colistimethate), and an aminoglycoside, gentamicin sulfate. Polymyxin B regularly prevented endotoxin-induced leukopenia, thrombocytopenia, and disseminated intravascular coagulation. Colymycin M had similar activity but was not as effective as polymyxin B. Gentamicin demonstrated no neutralizing ability in this study.

The in vitro susceptibilities of 150 clinical isolates of Pseudomonas aeruginosa to the aminoglycoside tobramycin and eight other antimicrobials were evaluated. The Food and Drug Administration standardized disk diffusion method showed that tobramycin inhibited 100% of the 150 isolates with gentamicin inhibiting only 90.7%. The difference between colistin (97.3%) and tobramycin was less marked. Carbenicillin (87.3%) was found to be slightly less active than gentamicin. Only a small percentage of the isolates were inhibited by the other drugs used. By using a minimal inhibitory concentration of 4 μg/ml in brain heart infusion broth as the level of susceptibility, it was found that only three of the isolates showed resistance to tobramycin, whereas 20 of the isolates were resistant to gentamicin. Approximately half of the isolates were inhibited by 0.5 μg/ml or less of tobramycin, whereas 1.5 μg of gentamicin per ml was required to inhibit 50% of susceptible strains.

BB-K8 (1) is a new semisynthetic derivative of kanamycin acylated with L(-)-Υ-ammo-α-hydroxybutyric acid (L-HABA) at the C-l amino group of the 2-deoxystreptamine moiety. The chemistry1) and antimicrobial activity1, 2)) of BB-K8 have been reported. The present paper describes the two configurational isomers of BB-K8, which bear the DL- and D-HABA residue at the C-l amino group of kanamycin A, as well as the three positional isomers of BB-K8, which are acylated with L-HABA at the C-3, C-6' and C-3" amino groups of kanamycin A.

Tobramycin belongs to the aminoglycoside class of antibiotics. Assay procedures were investigated to determine the most suitable methods for the assay of tobramycin in blood, urine, and pharmaceutical preparations. The agar-plate assay was the method of choice for determinations in urine and serum. The turbidimetric assay was selected for the assay of pharmaceutical preparations. An extraction technique is described that minimizes problems encountered in the estimation of tobramycin in urine. Sample diluents, p H, and molarity were important and were variable depending on assay methods. Evidence is presented to show binding of tobramycin to α-cellulose susceptibility discs. Iron and sodium ions demonstrated potential inhibition of tobramycin in all assay methods tested.

Physiological concentrations of calcium in serum antagonize the activities of colistin, polymyxin B, and gentamicin against Pseudomonas aeruginosa . Studies were carried out to determine whether tobramycin, a new aminoglycoside antibiotic, is also antagonized by calcium. The activity of tobramycin in vitro was shown to be antagonized by human serum and by physiological concentrations of calcium. The addition of human serum in broth-dilution tests produced a fourfold rise in the minimal inhibitory concentrations of tobramycin for five strains of Pseudomonas . In disc diffusion tests, the addition of calcium to the agar significantly decreased the size of inhibition zones, and the addition of a chelating agent to the agar increased the zone sizes. In a limited comparative study, tobramycin and gentamicin were tested against both light and heavy bacterial inocula of two strains of Pseudomonas . Tobramycin appeared to be antagonized less by serum than was gentamicin at equal antibiotic concentrations.

antimicrobial agents. Separate genetic determinants, grouped in various patterns on individual R factors, specify resistance to sulfonamides, penicillins and cephalosporins, chloramphenicol, tetracyclines, the kanamycin-neomycin group of antibiotics, and streptomycin, together with some related aminoglycoside antibiotics [1-3]. R factors are the predominant cause of clinically significant antibiotic resistance in gram-negative bacilli [2]. The mechanisms by which they mediate resistance have been studied intensively and, for the most part, consist of enzymatic inactivation of the antibiotics [1-8]. It is known that the degree of resistance mediated by R factors is often variable, dependent upon properties of the host cell and the R factor. Thus, cells of different enterobacterial genera may derive different degrees of resistance to streptomycin from R factors mediating resistance to this agent [1, 2, 9]. An analogous observation was made with R factors that mediated resistance to ampicillin by determination of the synthesis of a penicillinase that inactivated the antibiotic. Strains

Many papers have been presented on the enzymatic inactivation of the aminoglycosidic antibiotics by cell-free extracts obtained from drug-resistant strains of bacteria isolated from clinical specimens. Kanamycin is inactivated by two mechanisms responsible for the formation of 6-N-acetyl-kanamycin and 3'-phosphorylkanamycin. Similarly, streptomycin is inactivated by the formation of adenylylstreptomycin and phosphorylstreptomycin. These facts indicate that three mechanisms, i.e., phosphorylation, acetylation and adenylylation, involve in the inactivation of aminoglycoside antibiotics. It was reported previously that lividomycin, a new aminoglycosidic pentasaccharide antibiotic containing 2-deoxystreptamine, lacks the hydroxyl group at the C-3 position of the D-aminoglucose moiety and is not inactivated by a kanamycin-phosphorylating enzyme. This paper deals with the studies of anti-bacterial activity of lividomycin (LV) toward many strains of bacteria isolated from clinical specimens. The results are summarized as follows : 1) There are two types of LV-resistant strains. One group is capable of inactivating LV by phosphorylation and another group can not inactivate the drug.2) The inactivated product is a monophosphorylated LV.3) Chemical studies disclosed that the hydroxyl group at the 5″-position of the ribose moiety is phosphorylated.