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PubMed2003

In vitro sensitivity of Hungarian Actinobaculum suis strains to selected antimicrobials.

In vitro antimicrobial sensitivity of 12 Hungarian isolates and the type strain ATCC 33144 of Actinobaculum suis to different antimicrobial compounds was determined both by the agar dilution and by the disc diffusion method. By agar dilution, MIC50 values in the range of 0.05-3.125 micrograms/ml were determined for penicillin, ampicillin, ceftiofur, doxycycline, tylosin, pleuromutilins, chloramphenicol, florfenicol, enrofloxacin and lincomycin. The MIC50 value of oxytetracycline and spectinomycin was 6.25 and 12.5 micrograms/ml, respectively. For ofloxacin, flumequine, neomycin, streptomycin, gentamicin, nalidixic acid, nitrofurantoin and sulphamethoxazole + trimethoprim MIC50 values were in the range of 25-100 micrograms/ml. With the disc diffusion method, all strains were sensitive to penicillin, cephalosporins examined, chloramphenicol and florfenicol, tetracyclines examined, pleuromutilins, lincomycin and tylosin. Variable sensitivity was observed for fluoroquinolones (flumequine, enrofloxacin, ofloxacin), most of the strains were susceptible to marbofloxacin. Almost all strains were resistant to aminoglycosides but most of them were sensitive to spectinomycin. A strong correlation was determined for disc diffusion and MIC results (Spearman's rho 0.789, p < 0001). MIC values of the type strain and MIC50 values of other tested strains did not differ significantly. Few strains showed a partially distinct resistance pattern for erythromycin, lincomycin and ampicillin in both methods.

Actinomycetaceae↗
PubMed1976

Survival and fertility of antibiotic-treated bovine spermatozoa.

Motility of spermatozoa stored at 5 C with up to 1000 units or mug of chloramphenicol, polymyxin, kanamycin, tylosin, ampicillin, lincomycin, spectinomycin, erythromycin, novabiocin, or terramycin per ml of extender was compared to that with penicillin plus dihydrostreptomycin. Novabiocin and terramycin were toxic, but other antibiotic treatments had no effect. However, erythromycin and tylosin, as well as colymycin, depressed motility of frozen thawed spermatozoa. Spermatozoal motility was equivalent, following freezing in ampules or straws. All of the antibiotics which were non-toxic when added singly to frozen semen were also not harmful to frozen spermatozoa when as much as 2000 units or mug were added per ml of extender containing penicillin and dihydrostreptomycin. The addition of 1000 units or mug of ampicillin, chloramphenicol, kanamycin, lincomycin, polymyxin, or spectinomycin per ml of extender containing 750 units penicillin and 750 mug dihydrostreptomycin per ml did not influence the fertility of frozen spermatozoa in a field test involving 19,663 first inseminations.

Animals↗
PubMed2000

[In vitro activity of 12 antibiotics used in veterinary medicine against Mannheimia haemolytica and Pasteurella multocida isolated from calves in the Netherlands].

Results of susceptibility tests of clinical isolates of animal pathogens are periodically summarized and reported by the Animal Health Service. However, these results are based upon qualitative test methods. In the present paper results of quantitative susceptibility tests of twelve antibacterial agents against Mannheimia haemolytica (MHA) and Pasteurella multocida (PMU) isolated from Dutch calves in 1996 and 1997 are presented. Minimum inhibitory concentrations of amoxicillin, ceftiofur, tetracycline, trimethoprim-sulphamethoxazole, tilmicosin, neomycin, gentamicin, spectinomycin, flumequine, enrofloxacin, chloramphenicol and florfenicol were determined. No resistance was detected for ceftiofur and florfenicol. Three strains had an intermediate susceptibility to tilmicosin. The resistance percentages of MHA and PMU for neomycin, gentamicin, spectinomycin, flumequine, enrofloxacin, and chloramphenicol varied from 2% to 16%. Higher resistance percentages (16%-53%) were observed for amoxicillin, tetracycline, and trimethoprim-sulphamethoxazole. The MIC breakpoints used to determine whether a strain is susceptible, intermediate, or resistant are arbitrary and discussed in this paper.

Animals↗
PubMedDate not supplied

Minimum inhibitory concentration determinations for various antimicrobial agents against 1570 bacterial isolates from turkey poults.

Minimum inhibitory concentrations (MICs) were determined for 1570 bacteria from eight geographic locations (1204 Escherichia coli, 231 other enteric gram-negative bacilli [including Citrobacter spp., Enterobacter spp., Klebsiella spp., Proteus spp., and Salmonella spp.], 31 Pseudomonas spp., 18 coagulase-positive staphylococci, 26 coagulase-negative staphylococci, and 55 streptococci and enterococci) by the National Committee for Clinical Laboratory Standards broth microdilution procedure. Antimicrobial agents tested included ampicillin, ceftiofur, enrofloxacin, erythromycin, florfenicol, gentamicin, neomycin, spectinomycin, sulfamethazine, tetracycline, and trimethoprim/sulfadiazine. Against the E. coli strains tested, ceftiofur, enrofloxacin, gentamicin, and trimethoprim/sulfadiazine were the most active compounds with MIC at which 50% of the strains are at or below (MIC50) = 0.5, < or = 0.03, 0.5, and 0.13 microg/ml, respectively, and MIC at which 90% of the strains are at or below (MIC90) = 1.0, 0.13, 32.0, and 2.0 microg/ml, respectively. Ampicillin, florfenicol, neomycin, and spectinomycin were the next most active compounds against the E. coli strains, with MIC50 = 4.0, 4.0, 16.0, and 16.0 microg/ml, respectively. MIC90 values for these compounds against E. coli strains were > 32.0, 8.0, 512.0, and > 128.0 microg/ml, respectively. The remaining compounds exhibited limited, strain-dependent activity against the E. coli strains tested. As with the E. coli, enrofloxacin, ceftiofur, and trimethoprim/sulfadiazine were also the most active compounds against the 231 other enteric organisms tested, with MIC50 < or = 1.0 microg/ml for all of these genera. The remaining compounds exhibited limited activity against these genera. Against the gram-positive cocci tested, ampicillin, enrofloxacin, ceftiofur, and trimethoprim/sulfadiazine were most active, whereas the remaining compounds exhibited strain-dependent activity. When MIC data for E. coli were summarized separately, differences were observed between the geographic locations for the various antimicrobial agents. In conclusion, ceftiofur, enrofloxacin, and trimethoprim/sulfadiazine were the most active of the compounds tested against all of the bacterial strains.

Animals↗
PubMed2000

[Expression of Bacillus thuringiensis (Bt) crystal toxin gene in the chloroplast of tobacco].

The 3.5 kb wild-type Bt Cry I A(c) gene and its 3' truncated forms (2.1 kb, 1.8 kb) were placed under the control of plastid expression signals consisting of the strong light-induced psbA promoter and its 3' untranslated region with the aadA cassette (Prrn, aadA and psbA3') as a selectable marker. The resulting vectors pBT3, pBT8 and pBT22 also contain flanking tobacco plastid DNA homology regions to direct insertion of the Bt transgene into the tobacco plastid genome between psbA and trnK by homologous recombination. Transformed plastid genomes were selectively amplified by growing the cells on spectinomycin medium. Several independently transformed lines were obtained at last. The results of Southern and Western blot demonstrated that these three kinds of Bt genes had been introduced into tobacco plants, and their filial generations are resistant to spectinomycin. Insecticidal activity assay with transgenic tobacco leaves indicate that some plants have strong toxicity to cotton bollworm. This is the first report in China that Bt gene has been introduced and successfully expressed in the chloroplast of higher plants.

Bacillus thuringiensis Toxins↗
PubMed2000

Transplastomic Plants Homoplasmic for Foreign Transgenes.

Scientists pay more and more attention to the research on plastid engineering for its following advantages foreign genes can be integrated site-specifically into the plastid genome (plastome) there are no position effects as experienced with random insertion of transgenes in nuclear transformation pollen-mediated dispersion of transgenes can be avoided because chloroplasts are maternally transmitted gene silencing does not occur in plastids and therefore transgene expression is stable in progeny of transplastomic plants and the high ploidy level of the plastome in leaf cells makes high levels of transgene expression feasible. At the same time, however, the highly polyploid plastome makes it difficult to get transplastomic plants homoplasmic for foreign transgenes. In this work, chloroplast transforming vector pTRCH205, which carries two psbA5'-nifH-psbA3'and Prrn-aadA-TpsbA cassettes flanked by plastid DNA sequence to target their insertion between psbA and trnK operons, was constructed. Plastid transformation of Nicotiana tabacum was carried out by the biolistic delivery of transforming plasmid pTRCH205 DNA into leaf cells. Integration of nifH and aadA by two homologous recombination events via the flanking ptDNA sequences, and selective amplification of the transplastomes on MS medium with high concentration of spectinomycin, yielded resistant cell lines. All the independent transplastomic lines were subjected to three additional rounds of regeneration and were subcultured for 6--10 times through stem sections on MS medium containing 500 mg/L spectinomycin, to obtain homoplasmic tissues. The results of PCR assay and Southern blot hybridization, probed with 0.9 kb BglII/SnaBI homologous fragment, indicated that foreign genes had been integrated into the plastomes of transgenic plants, which finally became homoplasmic for foreign transgenes.

Journal Article↗
PubMed2003

Antimicrobial resistance of animal and human strains of Enterobacteriaceae in Greece.

Two hundred sixty two strains of Enterobacteriaceae from animal and human sources where intermixing and/or spreading is possible were examined for their resistance to 15 antimicrobials frequently used in animal prophylaxis and metaphylaxis. The antimicrobials with the highest proportion of resistant strains from animal sources were amoxicillin 25 mg, colistin sulphate 25 mg, erythromycin 5 mg, penicillin G 10 mg and spectinomycin 10 mg. The same with isolates from human sources where ampicillin 10 mg, amoxicillin 25 mg, colistin sulphate 25 mg, erythromycin 5 mg, neomycin 10 mg, penicillin G 10 mg and spectinomycin 10 mg. Human isolates were resistant to more antimicrobials than animal isolates. Common a high proportion of isolates from both sources were resistant to some antimicrobials. Systematic and better distributed information is needed to address the epidemiological role of veterinary treatment, prophylaxis and metaphylaxis in antimicrobial resistance in Greece.

Animals↗
PubMed2003

[Epidemiological and bacteriological characteristics of Neisseria gonorrhoeae isolates in China].

OBJECTIVE: To investigate the antimicrobial susceptibility,auxotype, and plasmid profile of Neisseria gonorrhoeae isolates in China and to provide evidence for the development of treatment guideline and policy for control. METHODS: Agar dilution was used to detect antimicrobial susceptibility. The auxotype was determined by GC genetic medium. The plasmid was extracted by alkaline cleavage and electrophoresed. RESULTS: A total of 4,976 gonococcal isolates were tested in the last 8 years. The resistant rate for penicillin was 71.60% with PPNG being 15.54%. Tetracycline-resistant (TRNG) isolates accounted for 93.02% with 10.48% high level tetracycline-resistant. The resistant rate for ciprofloxacin was also relatively high (31.78%). The resistant rates for spectinomycin and ceftriaxone were 0.36% and 0.46%. The predominant auxotypes of gonococcal isolates were proto and pro(-) during 1995 - 1996 in Nanjing, accounted for 46.4% and 47.53%, 48.4% and 50.22%, respectively. There were 8 strains harboring 4.2, 5.4, 39.5 kb plasmids and 2 harboring 4.2, 4.9, 5.4, 39.5 kb plasmids in 10 PPNG strains; 2 harboring no plasmid, 28 harboring 4.2, 4.9, 5.4, 39.5 kb plasmids in 30 non-PPNG strains. The 5.4 kb plasmid of PPNG could be digested with restriction endonuclease BamHI while the 5.4 kb plasmid of non-PPNG could not. CONCLUSION: The gonococcal isolates were highly resistant to penicillin, tetracycline, and ciprofloxacin, while were still sensitive to spectinomycin and ceftriaxone. No significant auxotyping change was found in terms of predominant gonococcal strains in the last two years in Nanjing while 5.4 kb plasmid might be the most prevalent resistant plasmid in Nanjing.

China↗
PubMed2005

[Sensitivity of clinical strains of Neisseria gonorrhoeae circulating in Yekaterinburg and the Sverdlovsk region].

The paper presents the results of determination of sensitivity of 154 gonococcal strains isolated from the patients, who were treated at the clinic of the Urals Research Institute of Dermatovenereology and Immunopathology and the Sverdlovsk Regional and Yekaterinburg City Dermatovenereological Dispensaries in 2001-2003, to penicillin, tetracycline, ciprofloxacin, ceftriaxone, spectinomycin, sparfloxacin, and moxifloxacin. It also shows the preponderance of moderately penicillin-resistant gonococci (75.3%) and their trend towards their transformation to resistant strains, tetracycline-resistant (74.0%), ciprofloxacin-sensitive (89%), and ceftriaxone-sensitive (82.5%) strains, as well as the absence of Neisseria gonorrhoeae resistant to spectinomycin, sparfloxacin, and moxifloxacin.

Anti-Bacterial Agents↗
PubMed2006

Characterization of antimicrobial resistance of Salmonella Newport isolated from animals, the environment, and animal food products in Canada.

Multi-drug-resistant (MDR) Salmonella enterica serovar Newport strains are increasingly isolated from animals and food products of animal origin and have caused septicemic illness in animals and humans. The purpose of this study was to determine the occurrence and the epidemiologic, phenotypic, and genotypic characteristics of S. Newport of animal origin that may infect humans, either via the food chain or directly. During the 1993-2002 period, the Office International des Epizooties Reference Laboratory for Salmonellosis in Guelph, Ontario, received 36 841 Salmonella strains for serotyping that had been isolated from animals, environmental sources, and food of animal origin in Canada. Of these, 119 (0.3%) were S. Newport. Before 2000, none of 49 S. Newport strains was resistant to more than 3 antimicrobials. In contrast, between January 2000 and December 2002, 35 of 70 isolates, primarily of bovine origin, were resistant to at least 11 antimicrobials, including the extended-spectrum cephalosporins. The blaCMY-2', flo(st'), strA, strB, sulII, and tetA resistance genes were located on plasmids of 80 to 90 MDa that were self-transmissible in 25% of the strains. Conserved segments of the integron 1 gene were found on the large MDR-encoding plasmids in 3 of 35 strains additionally resistant to gentamicin and spectinomycin or to spectinomycin, sulfamethoxazole-trimethoprim, and trimethoprim. Resistance to kanamycin and neomycin was encoded by the aphA-1 gene, located on small plasmids (2.3 to 6 MDa). The increase in bovine-associated MDR S. Newport infections is cause for concern since it indicates an increased risk of human acquisition of the infection via the food chain.

Animals↗
PubMed1989

Antimicrobial susceptibility of Neisseria gonorrhoeae isolated from maternal and child infections in Harare. The Puerperal Sepsis Study Group.

The in vitro antimicrobial susceptibilities of 29 PPNG and 26 non-PPNG isolated from women and neonates in Zimbabwe were investigated. There was evidence of chromosomal resistance to penicillin in many of the non-PPNG strains, with over 60 percent of all isolates having an MIC greater than 1 mg/litre. Reduced susceptibility to tetracycline was evident in about 20 percent of PPNG strains, particularly those containing the 4.4Md plasmid, while over 10 percent of non-PPNGs showed partial resistance to cefuroxime. Less than half of the strains were susceptible to erythromycin (MIC50 greater than 0.5 mg/litre) while all were susceptible to kanamycin and spectinomycin. PPNG containing the 3.2 Md plasmid were very susceptible to thiamphenicol (MIC50 0.25 mg/litre), while other strains were only moderately susceptible (MIC50 2 mg/litre). These findings suggest that penicillin, tetracycline or erythromycin may no longer be relied on for the successful treatment of gonococcal infection in women and babies. Thiamphenicol, Blactamase stable cephalosporins, kanamycin or spectinomycin may be useful alternatives, effective against most strains of both PPNG and non-PPNG. Continued surveillance is recommended to monitor changes in this susceptibility pattern.

Anti-Bacterial Agents↗
PubMed1989

[Study of the antimicrobial sensitivity, auxotype, serotype and plasmid analysis of 75 strains of Neisseria gonorrhoeae isolated in Barcelona].

The sensitivity of five antimicrobials (penicillin, cefoxitin, tetracycline, ceftazidime and spectinomycin) was assayed in 75 Neisseria gonorrhoeae strains, isolated from May 1986 to December 1987 in a general hospital in Barcelona. Auxotype, serotype and plasmid analysis studies were also performed on these strains. Twenty-six (34%) penicillinase-producing strains were found. 49% of the non-penicillinase-producing strains showed intermediate resistance to penicillin and 12% were resistant with MIC greater than 1 mg/1. 6% were resistant to tetracycline and cefoxitin, respectively, and all were sensitive to ceftazidime and spectinomycin. All the penicillinase-producing strains had the plasmid Africa and three of them had a diffuser plasmid of 24.5 mD. With regard to the auxotype study, most of the strains were prototrophic (38%) followed by the proline dependent ones (38%). 64% of the penicillinase-producing strains belonged to the serogroup W I, while 77% of the non-penicillinase-producing strains were in the W II/III serogroup.

Adolescent↗
PubMed1988

[Detection of penicillinase-producing Neisseria gonorrhoeae from male patients with urethritis].

Eighty-nine isolates of Neisseria gonorrhoeae from 89 male urethritis patients were studied for beta-lactamases (penicillinase) production, and their susceptibilities to benzylpenicillin, amoxicillin, piperacillin, clavulanic acid/amoxicillin (Augmentin), cephalexin, cefotaxime, spectinomycin and minocycline were determined by an agar plate-dilution method. Penicillinase activity was tested by a chromogenic cephalosporin method with nitrocefin as substrate (CefinaseTM discs, BBL, USA) and by a paper strip acidimetric method with benzylpenicillin as substrate (beta-Lactamase detection papers, Oxoid, UK). In addition, 60 of the 89 patients were examined for Chlamydia trachomatis, using fluorescein-labeled monoclonal antibodies (Direct specimen test; Micro TrakTM, Syva Co., USA). Penicillinase-producing N. gonorrhoeae (PPNG) were found in 12 of the 89 strains (13.5%). Although all these strains of PPNG were highly resistant to benzylpenicillin and amoxicillin, the minimum inhibitory concentrations (MICs) of Augmentin markedly decreased. Piperacillin was highly active against not only non-PPNG but also PPNG strains. More than half the isolates were resistant to cephalexin (MICs greater than or equal to 12.5 micrograms/ml) while all strains including non-PPNG and PPNG were fully sensitive to cefotaxime (MICs less than or equal to 0.20 microgram/ml). Spectinomycin and minocycline had MIC ranges of 6.25 to 25 micrograms/ml and 0.01 to 3.13 micrograms/ml, respectively; the ranges for non-PPNG and PPNG strains were fairly similar. C. trachomatis was detected in 11 (18.3%) out of 60 patients examined. The increasing incidence of PPNG and coexisting chlamydial infection should be taken into account in the treatment of gonococcal urethritis.

Adolescent↗
PubMed1988

[Penicillinase-producing Neisseria gonorrhoeae isolated in Lisbon 1982-1987].

PPNG strains were first detected in Lisbon in 1982. Most of the 88 PPNG strains isolated since then in our laboratory were obtained from prostitutes. In this population, PPNG prevalence underwent a dramatic increase, rising from 1.1% in 1983 to 8.2% in 1984, 19.2% in 1985, 13.1% in 1986 and 27% in 1987 (ten months). MICs determined by agar dilution in a sample of 45 non-PPNG strains were as follows: 0.063 less than MIC mg/l less than 2 for penicillin, 0.125 less than MIC mg/l less than 1 for ampicillin, 8 less than MIC mg/l less than 32 for spectinomycin, 0.125 less than MIC mg/l less than 2 for tetracycline, and MIC less than 0.063 for cefotaxime. In contrast, MICs among PPNG strains were 4 less than MIC mg/l less than 64 for penicillin, 4 less than MIC mg/l less than 64 for ampicillin, 16 less than MIC mg/l less than 32 for spectinomycin, 0.250 less than MIC mg/l less than 2 for tetracycline, and MIC mg/l less than 0.063 for cefotaxime. Two different inocula were used, ie. 2 X 10 CFU/spot, and 10 CFU/spot. A significant increase in MICs was found with the heavier inoculum, especially for beta-lactam antibiotics. Plasmid analysis of the PPNG strains found 44% type AFR-, 27% type Afr+, 13% type Asia-, and 13% type Asia+; one strain isolated in 1987 was similar to the "RIO" type (The Netherlands, 1985) with 3.05 Mdal. Distribution of auxotypes among studied strains was NR pheni, 44%, NR 14%; prol-, 31%; and other types, 11%.

Drug Resistance, Microbial↗
PubMedDate not supplied

Susceptibility of penicillinase-producing Neisseria gonorrhoeae in Ibadan to cefoxitin.

The minimum inhibitory concentration (MIC) of fourteen strains of penicillinase-producing Neisseria gonorrhoeae (PPNG) isolated in Ibadan to cefoxitin has been determined and compared with that of other antibiotics, viz. penicillin, ampicillin, thiamphenicol, spectinomycin, erythromycin and oxytetracycline. All the strains show high-level resistance to penicillin and ampicillin and the MIC of cefoxitin ranged from 0.5 to 16.0 micrograms/ml, with 71% of the strains having an MIC of 1.0 microgram/ml or less. The data suggest that cefoxitin may be a useful alternative to spectinomycin in the treatment of uncomplicated gonococcal infections, due to either PPNG or non-PPNG strains. However, further experiments and in vitro studies are indicated.

Cefoxitin↗
PubMed1983

[Epidemiology of Neisseria gonorrhoeae isolated in Switzerland: sensitivity to antibiotics and auxotyping].

In a study to determine the epidemiological situation of N. gonorrhoeae (NG) in Switzerland, 149 strains isolated from different regions over the period September 1981 to February 1982 were analyzed for sensitivity to various antibiotics (minimum inhibitory concentration [MIC] for penicillin G, ampicillin, cefuroxime, tetracycline, thiamphenicol, and spectinomycin) and for their auxotype. From the results obtained it can be concluded that (1) the PPNG (penicillinase producing NG) strains are not a problem at present in Switzerland; (2) 15% of the non-penicillinase producing NG strains are "less sensitive" to penicillin G (MIC equal to or greater than 0.5 micrograms/ml); (3) sensitivity level of the NG strains to the various antibiotics assayed and the auxotypes do not show any significant peculiarity when compared to the data reported in other countries; (4) penicillin G should still be used as the first choice antibiotic at present in Switzerland, with spectinomycin, thiamphenicol and cefuroxime as second choice antibiotics; (5) when compared according to the geographical origin of their isolation, the NG strains show specific peculiarities, a fact which could lead to an antibiotic therapy policy more suited to specific regions.

Anti-Bacterial Agents↗
PubMed1995

[Comparative activity of azithromycin against 100 strains of Neisseria gonorrhoeae].

Azithromycin is a new semisynthetic, acid stable C15 macrolid. In our study, we compared in vitro activity of azithromycin with 6 other antibiotics usually recommended for treatment of N. gonorrhoeae infections: erythromycin, ampicillin, amoxicillin, ceftriaxone, spectinomycin, ciprofloxacin. 100 strains have been selected: 95 clinical strains with different resistance patterns: 60 susceptible to beta-lactams, 25 PPNG, 10 chromosomal decreased susceptibility to beta-lactams. Among these strains, 13 had a decreased susceptibility to erythromycin (MIC: 2 and 4 mg/l) and 5 WHO reference strains: A: spectinomycin resistance, B: wild phenotype, C: chromosomal decreased susceptibility to penicillin and tetracycline, D: chromosomal resistance to penicillin and erythromycin+chromosomal decreased susceptibility to chloramphenicol, E: beta-lactamase producing strain (PPNG) and decreased susceptibility to tetracycline. MICs have been determined by GC agar dilution method. Azithromycin is more active than erythromycin on all N. gonorrhoeae patterns with a two log 10 difference for MIC50 and MIC90 (p < 0.0001). Because of pharmacokinetic properties and activity against Chlamydia trachomatis and urogenital mycoplasms often associated with N. gonorrhoeae, azithromycin is a good alternative for the treatment of genital infections.

Anti-Bacterial Agents↗
PubMed1976

[Resistance to beta-lactam antibiotics and aminoglycosides in gram negative bacteria. 2. Mechanism of resistance (author's transl)].

In a preceding paper the genetics of resistance of 2 representative strains exhibiting resistance to beta-lactam antibiotics (ampicillin, catbenicillin, cephalothin) to aminoglycosides (kanamycin, neomycin, paromomycin, gentamycin, sisomycin, tobramycin, streptomycin, spectinomycin) and further antimicrobials (tetracycline, chloramphenicol, suphonamides) were described. This paper reports about the mechanism of resistance to beta-lactam antibiotics and aminoglycosides in these strains. Enzymatic extracts from K. pneumoniae 1 and Serratia marcescens 2 were produced by the osmotic shock procedure. Incubation of these extracts with aminoglycoside antibiotics, to which the strains are resistant, and ATP resulted in the total inactivation of the antimicrobials, as measured with a Bacillus subtilis assay. Analysis of this inactivation with the radioactive methods of Davies and his colleagues revealed that the kanamycins, neomycins, paromomycin and gentamycin A were phosphorylated. Because butirosin was not a substrate for the phosphorylating enzyme, it was concluded that the strain produced the neomycin/kanamycin phosphototransferase I. Furthermore, it was found that streptomycin and spectinomycin were adenylylated by the enzymatic extracts as well as gentamycin C1a, C1, C2, A, tobramycin, sisomycin and the kanamycins. This substrate profile indicated the presence of two adenylylating enzymes: streptomycin/spectinomycin-adenylyl-transferase and gentamycin-adenylyltransferase. After transfer of multiple drug resistance by conjugation from both strains into C. coli K-12, sonified extracts were prepared and examined for enzymatic activity splitting beta-lactam antibiotics. The relative rates of inactivation of benzylpenicillin, ampicillin and cephaloridine as well as the inhibitory effect of cloxacillin, but not of p-chloro-mercuri-benzoate on the inactivation of cephaloridine indicated that both strains produced a class III/type a (TEM type) beta-lactamase. It is discussed that the increasing frequency of gram-negative organisms form the university hospital with identical resistant phenotypes as the strains examined is the result of the spread of an R-factor among the hospital bacterial flora.

Aminoglycosides↗