Comparative study of the influence of aminoglycoside antibiotics on the activity of the horizontal semicircular canal in the frog

This work is an electrophysiological study made in the frog. The technique allows one to test and to compare the actions of a number of aminoglycoside antibiotics, directly introduced into the labyrinthic cavity, on the spontaneous activity of a vestibular receptor--the horizontal semicircular canal. The effects of aminoglycoside solutions have been compared with those of physiological solutions (NaCl 7 g/l, Ringer) and of penicillin (not ototoxic). The results obtained show: (1) After the introduction of a physiological solution the activity disappears only very briefly (electrical artefact, probably); after a few minutes the activity returns to its initial value. A similar phenomenon is obtained with penicillin. (2) When used at a dose of 10 microgram, all the aminoglycosides studied generally induced an important and lasting decrease in semicircular canal activity. (3) These aminoglycosides have been classified according to their vestibular local toxicity. Their descending order of influence is as follows: streptomycin, dihydrostreptomycin, amikacin (BBK 8), neomycin, sisomycin, gentamicin and lividomycin, tobramycin, kanendomycin. (4) A parallel can be drawn between local vestibular toxicity and clinical ototoxicity. The role and importance of the hemolabyrinthic barrier are noted and the notion of ototoxicity is discussed.

A comparison of the in vitro activity of tobramycin and gentamicin against 6,042 clinical isolates

6,042 strains of Staphylococcus aureus, Streptococcus faecalis, Proteus mirabilis, Escherichia coli, Klebsiella sp. and Pseudomonas sp. were tested against tobramycin and gentamicin. Among all species studies, except Pseudomonas sp, gentamicin turned out to be slightly superior to tobramycin.

In vitro efficacy of Bay k 4999, a new ureido-penicillin, in combination with aminoglycosides against Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Proteus strains

The in vitro effects of Bay k 4999 in combination with gentamicin, tobramycin, amikacin sisomicin and netilmicin in bacteriostatic (MIC) and bactericidal (MBC) concentrations were compared using the checkerboard dilution technique against 20 different strains of Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and indole-positive-negative Proteus species. On average 63% of Bay k 4999-aminoglycoside (AG) combinations inhibited Pseudomonas, Proteus and Klebsiella strains additively and/or synergistically in bacteriostatic as well as in bactericidal concentrations as compared to only 14% additive or synergistic activity on E. coli. 35% of the combinations tested proved to be synergistic in K. pneumoniae, 20% in Proteus, 13% in Pseudomonas, but only 5% in E. coli. No significant differences between various Bay k 4999-AG combination effects could be demonstrated.

In vitro susceptibility of pseudomonas to four beta-lactamantibiotics (ampicillin, cephalothin, carbenicillin, piperacillin), to four aminoglycosides (kanamycin, amikacin, gentamicin, tobramycin) and to colimycin

Of 97 well-defined strains of Pseudomonas, isolated from sputum of patients with cystic fibrosis (CF), the minimum inhibitory concentration (MIC) of several antibiotics was determined with a broth dilution method. The majority of the strains were resistant to ampicillin and cephalothin, moderately susceptible to carbenicillin (70% to 100 microgram/ml) and highly susceptible to piperacillin (100% to 25 microgram/ml, 88% to 6.25 microgram and 60% to 3.12 microgram/ml). If the pharmacological properties of piperacillin are comparable with those of carbenicillin, it can be expected that the sputum level of this drug will be adequate to treat Pseudomonas pulmonary infections. At the lowest concentration tested (0.78 microgram/ml) 3% of the strains were susceptible to kanamycin, 85,5% to amikacin, 95% to gentamicin, 98% of tobramycin, and 80% to colimycin. With regard to clinically attainable concentrations, 98.9% of the strains were susceptible to gentamicin and tobramycin 97.9% to amikacin, 96.9% to colimycin, 88.6% to piperacillin, 38% to carbenicillin, 25.7% to kanamycin, 12.3% to ampicillin, and 1% to cephalothin.

R plasmids coding for supra-levels of gentamicin, tobramycin and sisomicin resistance in Proteus morganii and P. mirabilis: high-level resistant strains from two hospitals

Transfer of high-level gentamycin-tobramycin-sisomycin resistance could be easily demonstrated in strains of P. morganii and P. mirabilis which emerged, in two hospitals, at the end of 1976. First such strains were demonstrated in a patient of a urological ward who died, in September 1976, from generalised sepsis caused by a high-level gentamycin-tobramycin-sisomycin-resistant P. morganii. Since that event, at least nine such strains were isolated in 1976, and the presence of transferable resistant to the antibiotics listed plus other antibacterial substances including carbenicillin and more classical antibiotics could be demonstrated either by a high-frequence direct transfer to suitable recipient strains of Gentamycin or Tobramycin resistance, or by indirect selection, i.e. by analysis of exconjugants selected with kanamycin, streptomycin or carbenicillin. Further numerous strains of P. morganii highly resistant to gentamycin, tobramycin and sisomycin (M.I.C. over 128 mcg/ml) still emerge from wards in the two hospitals monitored and their transferability is under experimental study. It is stressed that, in order to demonstrate a transfer of gentamycin or tobramycin resistance in strains resistant to these substances, it is inevitable to examine properly also exconjugnants showing direct transfer to other, more classical antibiotics. We could not demonstrate, in our strains, any prodromal signs of resistance to netilmycin or amikacin.

The pH-dependent influence of aminoglycoside antibiotics on iodohippurate accumulation in rabbit renal cortical slices

The effects of aminoglycoside antibiotics on 125I-hippurate (OIH) accumulation in rabbit renal cortical slices were assessed in vitro using incubation media with pH-values ranging from 6.4 to 8.4 and containing streptomycin, kanamycin, amikacin, gentamicin and tobramycin in concentrations ranging from 100 to 2,000 microgram base/ml. The aminoglycoside-induced inhibition of OIH accumulation was clearly pH-dependent and most pronounced at alkaline pH-values. At pH 6.4 and 7.4 the aminoglycosides had either no or only moderate effects on OIH accumulation, while all drugs produced a distinct depression in accumulation at pH 7.9 and 8.4. The microbiologically inert N-acetyl gentamicin had no influence on accumulation. The influence of aminoglycosides on OIH accumulation is probably related to the pKa-values of these drugs and implies the presence of free amino groups.

[The use of tobramycin in severe infections (author's transl)]

The interest of tobramycin, studied here in 63 cases of severe infection, is due to several factors: --its ease of use including in cases of renal insufficiency; --the efficiency of subcutaneous administration, of particular interest to patients on anticoagulants; --its action on multi-resistant Enterobacteria and those not responding to gentamicin. Antibiotherapy is however only one of the elements of success in the treatment of severe infections, beside two factors which are often linked and determining: early treatment and the development of foci resistant to antibiotics.

A controlled investigation of the pharmacokinetics of gentamicin and tobramycin in obese subjects

For determination of the best basis on which to calculate dosages of gentamicin or tobramycin to be administered to obese patients, the pharmacokinetics of these drugs were studied in 13 obese subjects and 13 subjects of a normal weight following intravenous infusion of 1 mg/kg. Half-lives, elimination constants, and absolute and relative volumes of distribution were calculated. Concentrations of drug in serum were significantly higher and relative volumes of distribution were significantly lower in obese subjects as compared with controls. However, relative volumes of distribution based on lean body mass of obese subjects were significantly greater than those of normal-weight subjects. These results indicate that gentamicin and tobramycin are distributed less to adipose tissue than to other tissues, but partial distribution to adipose tissue does occur. The mean relative volume of distribution in obese subjects closely approximated that in normal subjects when normalized body mass plus 40% of the adipose mass was used as the total weight in obese subjects.

Inactivation of netilmicin by carbenicillin

Netilmicin was added to human serum and stored at various temperatures and carbenicillin concentrations prior to bioassay. Inactivation of netilmicin increased with temperature and carbenicillin concentration. The order of inactivation of aminoglycosides was: tobramycin greater than gentamicin, netilmicin greater than amikacin.

[The antimicrobial activity of amikacin in comparison with three other aminoglycoside-antibiotics (author's transl)]

We report about the in-vitro-sensitivity tests of 1756 Enterobacteriaceae and Pseudomonas strains to amikacin, gentamicin, tobramycin and sisomicin. It was established, that amikacin is more effective than gentamicin, tobramycin and sisomicin in case of infections with Klebsiella, Proteus species, Psuedomonas strains and Enterobacter. The four aminoglycosides are well active against E. coli. Hospital acquired infections with Serratia are a domain of amikacin. Tobramycin is more effective than gentamicin and sisomicin against Pseudomonas infections. Amikacin is the drug of choice against gentamicin-resistent strains, which are also not infrequently resistant to other aminoglycosides. Resistance to gentamicin-tobramycin and gentamicin-tobramycin-sisomicin, is most frequent among Klebsiella strains. The cross-resistance rate is considerably higher among Enterobacteriaceae strains than among Pseudomonas species. The lowest rate of resistance (2.1%) and the high antimicrobial activity are the considerable advantages of amikacin.

In vitro susceptibility of gentamicin and/or tobramycin resistant gram-negative bacilli to seven aminoglycosides

The in vitro activity of gentamicin, tobramycin, sisomicin, netilmicin, amikacin, kanamycin and streptomycin was tested simultaneously by the agar dilution method against 584 clinical isolates of gram-negative bacilli that were resistant to gentamicin and/or tobramycin. About half of the gentamicin-resistant Pseudomonas were susceptible to tobramycin but cross-resistance was virtually complete between gentamicin and tobramycin for Enterobacteriaceae. Sisomicin was much more active than gentamicin against Klebsiella, Escherichia and Citrobacter species. Only 18.9%, 27.4% and 27.9% of Klebsiella, Enterobacter and Serratia respectively were resistant to netilmicin. Amikacin was the most effective aminoglycoside with an overall resistance of 15.6%. Kanamycin was effective against 40% of Proteus and Providencia species. Surprisingly, more than half of Klebsiella and Enterobacter species and 85.3% of Serratia species were susceptible to streptomycin.

Susceptibilities of Pseudomonas species to tetracycline, minocycline, gentamicin, and tobramycin

Members of the genus Pseudomonas are widely implicated in human disease. Although most isolates are P. aeruginosa, there have been serious outbreaks of infection with other members of the genus. The susceptibility patterns of 5) Pseudomonas isolates are reported. It was notable that of the four antibiotics tested, uniform susceptibility was observed with minocycline.

Gentamicin-resistant gram-negative bacilli in hospital patients. Part II. In vitro aspects including susceptibility to tobramycin and amikacin

A study of 259 clinical isolates of gentamicin-resistant Gram-negative bacili (GRNB) has revealed 99,2% crossresistance with tobramycin and 6,9% with amikacin. Resistance to all 3 drugs is transferable in vitro. Simultaneous transfer of resistance to ampicillin, carbenicillin, cephalothin, tetracycline, chloramphenicol, sulphonamides, co-trimoxazole, streptomycin and kanamycin was shown to occur, emphasizing the potential for the selection of aminoglycoside-resistant organisms by the use of many other drugs. All GRNB studied were multiresistant. While amikacin should prove useful for those infections caused by GRNB which require treatment, care should be exercised in its use, to minimize the emergence of large-scale amikacin resistance.

Gentamicin-resistant gram-negative bacilli in hospital patients. Part I. Preliminary epidemiological assessment

Gentamicin-resistant Gram-negative bacilli (GRNB) have been isolated from specimens received from 23 hospitals in and around Johannesburg. Most isolates are fermentative in nature. A pilot survey among inpatients at the Johannesburg Hospital revealed an intestinal carriage prevalence of 14,3%. A prospective study of intestinal acquisition showed that GRNB are acquired in hospital, and that colonization is associated with prior antibacterial therapy. Analysis of clinical specimens received from the Johannesburg Hospital from 1 July to 30 September 1976 has indicated that intensive care and urology units are worst affected. An assessment of the overall prevalence of GRNB in October 1976 revealed that 16,1% of all Gram-negative bacilli were resistant to gentamicin. Major contributing factors are the widespread use of systemic aminoglycoside antibiotics, and a high rate of cross-contamination. Measures aimed at minimizing these factors have been introduced by the Johannesburg Hospital administration.

Tobramycin and neuromuscular transmission in the rat isolated phrenic nerve-diaphragm preparation

The effects of different concentrations of tobramycin, streptomycin, neomycin and gentamicin on the rat isolated phrenic nerve-diaphragm preparation are reported. Streptomycin, neomycin and gentamicin produced dose-dependent neuromuscular blockade. Tobramycin increased the muscle response at high concentrations (6.4 X 10(-4) - 2.6 X 10(-2) mol litre-1, but had no detectable effect when used in therapeutically recommended concentrations.

[In vitro antibacterial activity of tobramycin used in combination with cephalothin or carbenicillin (author's transl)]

Combinations of tobramycin (TOB) with cephalothin (CET) or carbenicillin (CBPC) were evaluated by in vitro test against 161 clinical isolates of Klebsiella pneumoniae, Escherichia coli, indole-positive Proteus, Enterobacter and Serratia marcescens which were not inhibited by 6.25 microgram/ml of CET. The combinations were considered to show synergy when there was a 4-fold or greater reduction in MIC values (FIC index less than or equal to 0.5) of both antibiotics when combined. Synergy of TOB with CET could be demonstrated against 83% of Klebsiella pneumoniae, 78% of E. coli, 44% of Proteus rettgeri and 39% of Proteus inconstans. Synergy of TOB with CBPC could be demonstrated against 78% of Proteus vulgalis, 45% of Serratia marcescens and 28% of Proteus inconstans. Bactericidal effect showing synergy of TOB with CET could be demonstrated against each 2 strains of Klebsiella pneumoniae and E. coli. Frequency of synergy of TOB with CET under the condition of large inoculum size was significantly higher than that of synergy of TOB with CET under the condition of small inoculum size. Synergy of bactericidal effect of TOB combined with CET against Klebsiella pneumoniae and E. coli was more active when they were combined at the same time, than those of when TOB was combined after 2 hours exposure by CET or when CET was combined after 2 hours exposure by TOB. No antagonistic action was observed in these studies.

Common plasmid specifying tobramycin resistance found in two enteric bacteria isolated from burn patients

Tobramycin-resistant burn wound isolates of Klebsiella pneumoniae and Enterobacter cloacae, together with Escherichia coli K-12 transconjugants from these two strains, were examined for plasmid deoxyribonucleic acid (DNA). All the resistant strains contained a common, high-molecular-weight, covalently closed circular DNA plasmid that was absent in the tobramycin-susceptible E. coli recipient strain. The common plasmid residing in E. cloacae was designated pIE098, and that residing in K. pneumoniae was designated pIE099. Both plasmid species were found to have a molecular mass of approximately 60 x 10(6) daltons and a guanine-plus-cytosine content of 50 mol%. The DNA that was extracted from all of the tobramycin-resistant strains tested was able to hybridize to 86 to 100% with pIE098 and pIE099 [(3)H]DNA generated by EcoRI to produce fragments of a size similar to those generated by BamHI. This study illustrates the usefulness of simple screening methods for antibiotic resistance plasmids in a hospital epidemiological situation.

Effect of cation content of agar on the activity of gentamicin, tobramycin, and amikacin against Pseudomonas aeruginosa

Fifty-five strains of Pseudomonas aeruginosa were tested against arithmetic increments in concentrations of gentamicin, tobramycin, and amikacin in 14 different lots of Mueller-Hinton agar. The divalent cation content of each lot was determined by atomic absorption spectrometry. The relation between mean minimal inhibitory concentration (MIC) for strains within each lot and cation content was studied by stepwise regression. Among the cations, the content of Zn++ most highly correlated with the MIC of each aminoglycoside; however, Zn++ accounted for only 23%, 60%, and 47% of the variability in the mean MIC of gentamicin, tobramycin, and amikacin, respectively, against all strains. In two-cation models Zn++ with Ca++ or Cu++ was most highly correlated with the mean MICs of the three aminoglycosides against all strains. No divalent cation, either singly or in combination with one or two other cations, gave a good prediction of the MICs of the aminoglycosides in agar. Furthermore, there was variability in the cations that most highly correlated with the MICs for some strains. These observations support the concept that ionic strength, cations, and a variety of other as yet poorly defined components of media influence the activity of aminoglycosides against P. aeruginosa.

Mezlocillin: a new acyl ureidopenicillin. Antimicrobial activity and combination effects with four aminoglycoside antibiotics

Mezlocillin (Baypen), carbenicillin and mezlocillin combined with gentamicin, sisomicin, tobramycin and amikacin, respectively, were tested in vitro against 325 fresh clinical isolates of pathogenic gram-negative bacteria using the tube dilution procedure. The new acyl ureidopenicillin has a greater antimicrobial activity than carbenicillin against nearly all species tested. The comparison of the effectiveness of the mezlocillin-aminoglycoside combinations demonstrates the superiority of mezlocillin-sisomicin against Escherichia coli, Klebsiella, Serratia and Proteus spp., whereas mezlocillin-tobramycin is most active against gentamicin-sensitive Pseudomonas aeruginosa, and mezlocillin-amikacin against Enterobacter and gentamicin-resistant P. aeruginosa. The combination effects achieved in the majority of strains were addition or synergism. The resistance rate and the bactericidal efficacy of mezlocillin were clearly improved when mezlocillin was combined with aminoglycoside antibiotics. Mezlocillin-amikacin showed the lowest resistance rate (10.2%) followed by mezlocillin-sisomicin (12.3%), mezlocillin-gentamicin (15.1%) and mezlocillin-tobramycin (18.5%). In most species, mezlocillin-sisomicin has proved to be the combination with the best bactericidal potency.

Frequency of resistance to kanamycin, tobramycin, netilmicin, and amikacin in gentamicin-resistant gram-negative bacteria

In vitro evaluation of 66 epidemiologically distinct, gentamicin-resistant, gram-negative isolates from four hospitals revealed that 92% were kanamycin resistant, 44% were netilmicin resistant, 41% were tobramycin resistant, and 6% were amikacin resistant. Combined resistance to gentamicin, tobramycin, and netilmicin occurred in 30% of the strains. Although the resistance percentage to amikacin was the lowest of the three newer agents, two strains were resistant to all of the aminoglycosides tested.

Specific and non-specific resistance to aminoglycosides in Escherichia coli

The turbidimetric responses of a strain of Escherichia coli K12 to gentamicin and tobramycin were investigated. Both agents showed antibacterial activity below the conventionally measured minimum inhibitory concentration, but exposure to such subinhibitory concentrations of either agent generated a bacterial population which was able to grow in previously inhibitory concentrations at a rate equivalent to that of the parent culture. The increase in resistance was non-specific in that both aminoglycosides were equally affected, and was unstable on multiple passage in drug-free broth. The response to tobramycin was unaffected by the presence of an R factor conferring gentamicin resistance, but exposure of the R factor bearing strain to gentamicin caused a concomitant increase in the resistance to tobramycin, apparently by a non-specific adaptive mechanism similar to that observed with the parent strain. It is suggested that prior treatment of a gentamicin-resistant organism with gentamicin (as may occur during blind therapy) may adversely affect the subsequent response to other aminoglycosides.

Effects of sputum from patients with cystic fibrosis on the activity in vitro of 5 antimicrobial drugs on Pseudomonas aeruginosa

By in vitro tests on 12 strains of Pseudomonas aeruginosa, sputum from patients with cystic fibrosis sharply increased the minimal bactericidal concentrations of polymyxin B and neomycin. Sputum had a lesser effect on tests with gentamicin and tobramycin and essentially none on tests with carbenicillin.

Sensitivity of strains of enteropathogenic Escherichia coli to tobramycin and other antibiotics

The sensitivity patterns of strains of enteropathogenic Escherichia coli associated with diarrhoeal disease of infants to tobramycin and other antibiotics were estimated. The activity of tobramycin and of gentamicin alone and in combinations against recent isolates of enteropathogenic Escherichia coli was investigated. It was found that all the strains included in the present study were sensitive to tobramycin and gentamicin and most of them were sensitive to colistin and furazolidone. No significant differences in minimal inhibitory concentrations (MICs) and rates of killing were found between tobramycin and gentamicin, and they acted in an additive manner against most of the strains tested.

Emergence in a burn center of populations of bacteria resistant to gentamicin, tobramycin, and amikacin: evidence for the need for changes in zone diameter interpretative standards

From July 1974 through June 1976, a number of isolates of Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa from the Burn Center exhibited a shift to smaller zone diameters with gentamicin than did isolates from the general hospital population. Although many had zone diameters >/=13 mm and would have been considered susceptible by this breakpoint, they were found to have minimal inhibitory concentrations (MICs) of >/=8 mug of gentamicin per ml by agar dilution testing. Zone diameters and MICs of gentamicin, tobramycin, and amikacin were subsequently compared for 168 isolates from both the Burn Center and general hospital. The results revealed many isolates that fell into presently used gentamicin- and tobramycin-"susceptible" categories by disk diffusion tests but were resistant by MIC. The data indicated that criteria for gentamicin disk diffusion testing should include an intermediate or indeterminate category, and that the limits of the intermediate category for tobramycin and amikacin should be expanded.

Antimicrobial susceptibility of gentamicin-resistant Pseudomonas aeruginosa

The susceptibility of 41 strains of gentamicin-resistant Pseudomonas aeruginosa to tobramycin, sisomicin, netilmicin, amikacin, and carbenicillin was determined. Amikacin and carbenicillin exhibited the greatest activity against these strains and especially against those with a high level of resistance to gentamicin. Netilmicin exhibited little activity, whereas tobramycin and sisomicin were active against approximately two-thirds of the strains. Cross-resistance to tobramycin, sisomicin, and netilmicin was frequent.

A multicentre study of the susceptibility of a variety of bacteria to cephalothin, cefamandole, tobramycin and gentamicin

A multicentre study of antibiotic susceptibility was performed in South Africa. Sensitivity to cephalothin, cefamandole, tobramycin and gentamicin was tested on a variety of aerobic and anaerobic bacteria. Two disc susceptibility techniques were used, i.e. the Kirby-Bauer technique (aerobes) and the broth-disc method (anaerobes); minimum inhibitory concentrations (MICs) were determined according to the International Collaborative Study techniques, and regression lines for individual centres were constructed. Satisfactory lines were obtained for cephalosporins, but, in some centres, problems were experienced with the aminoglycosides. Variations in MICs for Haemophilus influenzae were probably due to an inoculum effect. Accumulative percentage tables of the number of strains inhibited were compiled, and the comparative performance of the antibiotics was assessed.

Transduction, by phases F116 and G101, of gentamicin-tobramycin resistance, and of "autoplaque formation" property in Pseudomonas aeruginosa

Pseudomonas aerugionsa phages F 116 and G 101, propagated on ML 4262 strain into which gentamicin-tobramycin resistance determinants have been increased by means of conjugation, from wild-type strains Vy 28, 29 and 34, were capable to transduce R determinants to PAO 1670 strain. Transfer ability was co-transduced as well, with exception of transductants selected with streptomycin. "Autoplaque formation" ability, occurring in original wild-type strain Vy 28, could be co-tranduced with all tobramycin-resistant determinants by F116 but not G 101 phage.

Antimicrobial agents--Part II. The aminoglycosides: streptomycin, kanamycin, gentamicin, tobramycin, amikacin, neomycin

Aminoglycoside antibiotics are poorly absorbed from the gastrointestinal tract, do not penetrate well into the cerebrospinal fluid, are minimally bound to plasma proteins, and are rapidly excreted by the normal kidney. Neomycin is limited by its toxicity to irrigating and topical preparations or to oral medication for surgical bowel preparations or hepatic coma. Streptomycin has only a few specific indications, because newer agents are available that have broader spectrums of activity. Kanamycin is indicated in serious gram-negative infections in which Pseudomonas aeruginosa is not a likely causative agent. Gentamicin, tobramycin, and amikacin are effective against a broad spectrum of gram-negative organisms including P. aeruginosa. In general, both gentamicin and tobramycin are more active in vitro than amikacin on a weight basis; however, higher serum levels are achievable with amikacin than with the two others. Amikacin is probably the aminoglycoside of first choice when gentamicin resistance is strongly suspected.

Community-acquired Acinetobacter calcoaceticus var anitratus pneumonia

Two patients had community-acquired Acinetobacter calcoaceticus var anitratus pneumonia. Both patients were alcoholic and one was cirrhotic. One patient died and the other received two weeks of gentamicin therapy and survived. Misinterpretation of the sputum Gram stain delayed diagnosis and institution of proper therapy in both cases. In addition to organisms sensitive to penicillins such as Neisseria or Haemophilus, Acinetobacter must be considered in the differential diagnosis of community-acquired Gram-negative coccobacillary pneumonia.

[Study of antibiotic sensitivity in 34 strains of large colony mycoplasma (author's transl)]

The application of Steer's technic to large colony mycoplasma for the study of antibiotic sensitivities, permitted us to compare the activity of various molecules inhibiting protein synthesis. Among large colony mycoplasmas, only mycoplasma pneumoniae is sensitive to erythromycin but we have already isolated a strain resistant at 400 microgram/ml. This should be remembered during treatment of mycoplasma pneumoniae infections. This species always remains sensitive to tetracycline. Among the latter, doxycyclin and minocyclin are preferred, firstly for their greater efficacy in vitro and secondly their better pharmacodynamic criteria. Gentamicin, tobramycin and chloramphenicol are also active in vitro. No trial in vivo has been carried out.

The pharmacology of newer aminoglycosides, with a consideration of the application to clinical situations

This has been an overview of the pharmacology of tobramycin, a new potent aminoglycoside, particularly active against Pseudomonas aeruginosa. Close attention must be given to the administration of this compound, and to the administration of all aminoglycosides, if one is to achieve adequate serum and tissue concentrations without provoking a toxic renal or otic reaction. Differences in methods and dosage of administration depending upon age, status of renal function, and route of administration are discussed. The basic principles reviewed can be applied to all the agents in this class.

Recent advances in antimicrobial therapy

Metronidazole is a relatively nontoxic, oral agent which may prove to be useful in the treatment of infections caused by susceptible anaerobic organisms. Use of metronidazole to treat anaerobic infections presently is investigational.