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PubMed1988

Comparison of the in vitro activity of ciprofloxacin and 24 other antimicrobial agents against clinical strains of Chromobacterium violaceum.

Eleven clinical strains of Chromobacterium violaceum were tested for their susceptibility to 25 antimicrobial agents. Ciprofloxacin was the most active of the compounds tested although norfloxacin and pefloxacin were highly active. No resistance was detected to mezlocillin, piperacillin, apalcillin, imipenem, and aztreonam while a single strain was resistant to ticarcillin. Among the cephalosporin/cephamycin group only cefotetan showed good in vitro activity. Gentamicin was more active than amikacin and tobramycin. Good in vitro activity was also noted for chloramphenicol, doxycycline, and trimethoprim-sulfamethoxazole while C. violaceum strains were highly resistant to rifampin and vancomycin. The bactericidal activity of selected agents was shown to be concentration dependent using time-kill kinetic studies. Addition of clavulanic acid did not increase the activity of ticarcillin and in one case was shown to induce beta-lactamase. High correlation was noted between the broth microdilution and disk diffusion susceptibility tests in predicting the susceptibility patterns of C. violaceum.

Chromobacterium↗
PubMed1989

Antimicrobial activities and susceptibility testing considerations of ampicillin, cephalothin, cefaclor, and cefuroxime against invasive isolates of Haemophilus influenzae.

The activities of ampicillin, cefaclor, cephalothin, and cefuroxime against invasive clinical isolates of Haemophilus infleunzae were studied to determine the correlation between resistance and beta-lactamase production. Approaches to in vitro susceptibility testing of cephalosporins in the clinical laboratory were also assessed. Three hundred and eight isolates of H. influenzae were tested for ampicillin susceptibility, and those which required for inhibition greater than or equal to 1.0 micrograms/ml of ampicillin were tested for beta-lactamase production with a chromogenic cephalosporin. Twenty-two percent of isolates produced beta-lactamase and 85% were serotype b. All isolates considered resistant (MIC greater than or equal to 2.0 micrograms/ml) to ampicillin produced beta-lactamase. A single beta-lactamase-producing isolate was identified, but was inhibited by 1.0 microgram/ml of ampicillin, and a zone diameter of 20 mm was produced by disk diffusion testing. One hundred and ninety-seven isolates were tested for susceptibility to cefaclor, cefuroxime, and cephalothin. Chloramphenicol susceptibility testing by disk diffusion was also performed on these isolates. General agreement and interchangeable results were found among these three cephalosporins by both agar dilution and disk diffusion methods. We conclude that ampicillin-resistant H. influenzae not producing beta-lactamase is rare among these isolates of H. influenzae responsible for invasive disease. Susceptibility testing results of cephalothin, cefaclor, or cefuroxime appear to be interchangeable, although results of cephalothin testing would tend to underestimate the activities of cefaclor or cefuroxime.

Ampicillin↗
PubMed1986

Selection of a reference lot of Mueller-Hinton agar.

A collaborative study was undertaken to evaluate the performance of currently marketed Mueller-Hinton agars from seven manufacturers by replicate disk diffusion tests with standard quality control strains. Identification of the manufacturers was concealed, and the resulting data were evaluated for the selection of a physical reagent standard against which the performance of future production lots would be tested and made to conform. A medium was selected which was sufficiently close to existing National Committee for Clinical Laboratory Standards quality control limits that current interpretive criteria would require minimum modification. Two of the seven lots were eliminated from further consideration because the final pHs were outside acceptable limits. The remaining four lots had 96% of mean zone diameters less than or equal to 2 mm from those of the chosen lot and 65% of the means were less than or equal to 1 mm from those of the chosen lot for all 28 antimicrobial agent-organism combinations. Manufacturers then attempted to produce new lots of Mueller-Hinton agar which performed within the prescribed limits of the chosen lot. One lot performed in close conformity with the selected standard, but the overall performance of the media was essentially the same as that of the randomly chosen lots in the initial study. It was concluded that one of the original seven lots demonstrated properties which made it a tentative candidate for a physical reagent standard and that the use of a physical reagent standard in evaluating production lots might aid in stabilizing the performance of Mueller-Hinton agar.

Agar↗
PubMed2003

In vitro activity of daptomycin against vancomycin-resistant enterococci of various Van types and comparison of susceptibility testing methods.

The increasing prevalence of vancomycin-resistant enterococcal (VRE) infections and the limited number of antimicrobial agents for their treatment emphasize a need for new, more effective agents. In this study, the in vitro activity of daptomycin was determined against a collection of 156 VRE from seven different institutions. Van types were characterized by PCR, and pulsed-field gel electrophoresis was performed to exclude isolates with >85% relatedness by dendrogram. Included were 126 Enterococcus faecium (109 vanA, 17 vanB) isolates, 5 Enterococcus faecalis (3 vanA, 2 vanB) isolates, 2 Enterococcus avium (vanA) isolates, 1 Enterococcus durans (vanA) isolate, 10 Enterococcus gallinarum (vanC1) isolates, and 12 Enterococcus casseliflavus (vanC2) isolates. MICs of daptomycin and five additional agents were determined by the NCCLS broth microdilution method with Mueller-Hinton (MH) broth containing supplemental calcium. MICs were also determined using two investigational E-test strip formulations, and disk diffusion testing was performed by the standard NCCLS method. The MIC of daptomycin at which 50% of the isolates tested were inhibited for this isolate collection was 4 microg/ml, and the MIC at which 90% of the isolates tested were inhibited was 8 microg/ml. Two isolates of vanA E. faecium were resistant to linezolid, and one isolate was resistant to quinupristin-dalfopristin. MICs of daptomycin determined by the E test with and without added calcium varied by 8- to 16-fold, and disk diffusion zones varied by 3 to 6 mm according to the calcium content of the commercial MH agar lots used in the study. This study has shown daptomycin to have good activity against a diverse collection of contemporary VRE isolates. However, improved standardization of the calcium content of MH agar will be important for reliable testing of daptomycin by clinical laboratories using either the E test or disk diffusion methods.

Anti-Bacterial Agents↗
PubMed1983

Rapid and economical identification and antimicrobial susceptibility test methodology for urinary tract pathogens.

To decrease the time and cost of processing urine cultures, we devised a critical pathway to identify and perform antibiotic susceptibility tests on commonly isolated microbial pathogens within 6 h of growth detection. The strategy was based on eliminating expensive kits and automated procedures when not required. A pathway utilizing a statistical matrix and three rapid biochemical tests required to identify the most common pathogen, Escherichia coli, was developed. This species, which represented 82% of urinary isolates, was identified in 1 h for less than 10% the cost of a commercial kit. The specificity of the 1-h E. coli identification battery was greater than or equal to 99.9% with a sensitivity of 93%. In addition, this critical pathway, adapting published methods, permitted the identification of other enteric pathogens, the group D streptococci, and Pseudomonas aeruginosa within 4 to 6 h. Furthermore, it accounted for other microbes that required longer periods of incubation. The pathway also included a rapid disk diffusion sensitivity test. Utilizing the critical pathway strategy, 76% (E. coli frequency of 0.82 X E. coli sensitivity of 0.93) of all urinary pathogens were identified within 1 h, and 98% were identified within 4 h with an antibiotic sensitivity test available within 6 h after the observation of growth. Costs were reduced from 2.5 to 5.0 times. This methodology is applicable to other specimen types.

Anti-Bacterial Agents↗
PubMed2006

Antimicrobial effect of silver-doped phosphate-based glasses.

In this study a range of phosphate-based glasses (PBG) doped with silver have been investigated for their antimicrobial activities. In disk diffusion assays, these compositions demonstrated microbistatic effects against a range of organisms including Staphylococcus aureus, Escherichia coli, Bacillus cereus, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and Candida albicans. The data obtained from the above studies allowed for an additional range of PBG containing lower amounts of silver to be studied for their effects on the growth and viability of S. aureus, E. coli, and C. albicans. PBG containing 3 and 5 mol % Ag were bactericidal for S. aureus and E. coli and significantly decreased the growth rate of C. albicans. A decrease in the dissolution rates of the glasses was seen with increasing Ag content over the range of concentrations investigated. Overall, 3 mol % Ag incorporated into the PBG investigated was sufficient to mount a potent antibacterial effect against the test organisms, and these compositions also gave excellent long-term release of Ag ions into the medium.

Anti-Bacterial Agents↗
PubMed2000

[Nitrofurans: a modern treatment for uncomplicated urinary infections?].

From January 1995 to December 1998, 2,912 strains of enteric bacilli were isolated from the urinary tract. Increasing antibiotic resistance in Enterobacteriaceae as a cause of urinary tract infection (UTI) led us to reevaluate first- and second-line therapies. We studied antimicrobial susceptibilities of these strains to norfloxacin (NOR), nalidixic acid (NAL), trimethoprim sulfamethoxazole (TS) and nitrofurantoin (FT) using the disk diffusion method. These results show no significant superiority of the activity of nitrofurantoin against Enterobacteriaceae compared with the other antibiotics with sustained concentration in urine. However, if we consider only multiresistant Enterobacteriaceae (cefotaxime resistant), this molecule appears to be very active. These results show a significant superiority of nitrofurantoin in vitro against these multiresistant Enterobacteriaceae. Thus, this molecule could once again become a good choice for the treatment of uncomplicated UTI.

Anti-Infective Agents, Urinary↗
PubMed2005

Chemical composition and antibacterial activity of the essential oil and the gum of Pistacia lentiscus Var. chia.

The essential oil and gum of Pistacia lentiscus var. chia, commonly known as the mastic tree, are natural antimicrobial agents that have found extensive uses in medicine in recent years. In this work, the chemical composition of mastic oil and gum was studied by GC-MS, and the majority of their components was identified. alpha-Pinene, beta-myrcene, beta-pinene, limonene, and beta-caryophyllene were found to be the major components. The antibacterial activity of 12 components of mastic oil and the oil itself was evaluated using the disk diffusion method. Furthermore, attempts were made to separate the essential oil into different fractions in order to have a better picture of the components responsible for its antibacterial activity. Several trace components that appear to contribute significantly to the antibacterial activity of mastic oil have been identified: verbenone, alpha-terpineol, and linalool. The sensitivity to these compounds was different for different bacteria tested (Escherichia coli, Staphylococcus aureus, and Bacillus subtilis), which suggests that the antibacterial efficacy of mastic oil is due to a number of its components working synergistically. The establishment of a correlation between the antibacterial activity of mastic oil and its components was the main purpose of this research. Mastic gum was also examined, but it proved to be more difficult to handle compared to the essential oil.

Acyclic Monoterpenes↗
PubMed1981

Quality control limits for ampicillin, carbenicillin, mezlocillin, and piperacillin disk diffusion susceptibility tests: a collaborative study.

A multilaboratory in vitro study was carried out to determine disk diffusion susceptibility testing quality control limits for two new semisynthetic penicillins, mezlocillin and piperacillin. Existing limits for carbenicillin and ampicillin were reevaluated. Multiple tests (which followed standards set by the National Committee for Clinical Laboratory Standards ASM-2 revised) were performed in nine laboratories by different technologists using disks and Mueller-Hinton agar from different manufacturers. Clinically significant differences between disks produced by different manufacturers were not noted. Inhibitory zone diameter measurements from all laboratories were analyzed, and upper and lower control limits were established by using the overall median +/-0.5 the median range of the individual laboratory measurements as determining parameters. Close agreement of the data in this study with the results of national proficiency testing and quality control programs for ampicillin and carbenicillin supports the validity of our approach to making initial recommendations for quality control guidelines for new antimicrobial agents.

Ampicillin↗
PubMed1976

A Rapid, simple method for demonstrating synergy of amikacin and penicillin against various microorganisms.

A simple disk diffusion technique with use of triple-layer agar and enzymatic inactivation of penicillin demonstrated synergy between penicillins and aminoglycosides. The method was applied to measurement of the synergistic activity of amikacin and penicillin G against a strain of Streptococcus faecalis sensitive to both drugs, amikacin and ampicillin against a strain of S. faecalis sensitive to amplicillin but resistant to amikacin, and amikacin and carbenicillin against a strain of Proteus mirabilis sensitive to both drugs. The degree of synergy was related to the specific organism tested. For example, syngery of penicillin G and amikacin for S. faecalis could be demonstrated only when the organism was subjected first to the action of penicillin G alone. In addition to providing useful clinical information, the triple-layer technique appears to be a promising tool for the study and understanding of synergy between antimicrobial agents.

Amikacin↗
PubMedDate not supplied

[Bacteria isolated from pleural fluid and their resistance to antimicrobials].

The aim of this study is to evaluate the frequency of microorganisms isolated from pleural fluids and their resistance to antimicrobial agents. A total of 272 pleural fluids were studied between July 2004 - July 2005 from the patients hospitalized in ICU/surgery (127) and respiratory diseases wards (145) at Marius Nasta Institute. The laboratory investigations included: direct microscopy, cultures for aerobic and anaerobic bacteria, identification, disk diffusion method according with CLSI recommendations for resistance and Etest for detection of metallo-beta-lactamase producing isolates of Pseudomonas aeruginosa. Microorganisms were isolated from 159 samples (58.4%), 48 pleural fluids were positive only in microscopy (17.6%). The most frequent isolated strain was P. aeruginosa (49.6%), followed by Staphylococcus aureus (12.8%) and Enterobacteriaceae (11.2%) polymicrobial infections were mostly due to combinations of Pseudomonas with Enterobacteriaceae. For P. aeruginosa the resistance rate was higher than 71% for all beta-lactams. For aminoglycosides the lower resistance rate was to amikacin (18.0%). For quinolones, resistance of P. aeruginosa was 67.8% to ciprofloxacin. P. aeruginosa isolated from patients hospitalized in ICU/surgery were more resistant to some antimicrobials than the strains isolated in the respiratory diseases wards: resistance to amikacin was 24.5% versus 10% respectively. From 21 P. aeruginosa imipenem and multidrug resistant strains tested, 3 were probably producing of metallo-beta-lactamase. S. aureus showed 47.1% oxacillin resistance, 38.9% resistance to gentamicin and ciprofloxacin and 27.7% to erythromycin. All S.aureus strains were susceptible to linezolid, teicoplanin and vancomycin. The resistance of Enterobacteriaceae strains was high to ampicillin (80.0%), amoxicillin/clavulanic acid and trimethoprim/sulfamethoxazole e(57.6%); the lowest resistance rate was to cefoperazone/sulbactam (7.7%) and to imipenem and ciprofloxacin (10.8%).

Anti-Bacterial Agents↗
PubMed2005

Antimicrobial resistance profiles of dairy and clinical isolates and type strains of enterococci.

The susceptibility to 30 antimicrobial agents was determined by the disk diffusion method for a collection of 172 enterococcal strains, including 96 isolates from dairy sources, 50 isolates of human and veterinary origin, and 26 reference strains from 24 different enterococcal species. Results were analysed by hierarchic numerical methods to cluster strains and to group antimicrobials according to similarity profiles. Resistance to 17 of the 30 antimicrobials showed to be correlated, leading to four groups reflecting the mode of action: quinolones (ofloxacin, enrofloxacin, ciprofloxacin and norfloxacin); macrolides (erythromycin, spiramycin), phenicols (cloramphenicol) and tetracyclins (tetracycline, oxytetracyclin); aminoglycosides (gentamicin, kanamycin) and lincosamides (clindamycin); penicillins (amoxicillin, ampicillin, penicillin G, piperacillin) and carbapenems (imipenem). Overall, the genus Enterococcus behaved as resistant to lincomycin, colistin, polimixin B and, with a few exceptions in dairy isolates, to methicillin. In general, all isolates were susceptible to vancomycin, cloramphenicol and fusidic acid. Clusters containing only dairy isolates were susceptible to the majority of antimicrobials tested, as opposed to clusters constituted only by clinical enterococcal isolates. Among the clinical isolates, 62% were highly multiresistant. Low level gentamicin resistance was found to be associated with clinical enterococci. Among dairy isolates, those that clustered with clinical isolates were both resistant to gentamicin and identified as Enterococcus faecalis. Resistance to macrolides, quinolones, penicillins and imipenem was found to be associated also with clinical environments, mainly with multiresistant isolates, contrary to what is generally agreed as a characteristic of the genus. Veterinary clinical isolates were mainly grouped with the multiresistant clinical human isolates. The 26 reference enterococcal strains were distributed in clusters with different antibiotic resistance profiles and were mainly clustered with dairy isolates.

Anti-Bacterial Agents↗
PubMed2003

Campylobacter and fluoroquinolones: a bias data set?

There is no universally accepted standard method for the isolation of Campylobacter spp. and it is considered that currently available isolation media are not yet optimal for the recovery of Campylobacter spp. from a range of sample types. Almost all methods incorporate antibiotics into the isolation media to inhibit growth of other bacteria within the sample. It is established that the incorporation of such antibiotics into isolation media will inhibit the growth of some Campylobacter spp. as well as other bacteria. The results of the use of such suboptimal isolation methods are that the isolates which 'survive' the isolation procedure will be those which: (i) are able to 'out compete' the rest of the bacteria in the sample, i.e. they are able to grow faster; (ii) are resistant to the antibiotics used in the isolation media; and (iii) are randomly selected by the laboratory technician as being a 'typical'Campylobacter spp. It is clear that such a procedure is intrinsically biased and will mean that species resistant to the antibiotics used in the media will be isolated. This introduces real doubt that the bacteria isolated are truly representative of those initially found on the sample. It is also becoming clear that Campylobacter spp. are rather difficult to isolate as pure cultures and many are in fact mixtures of more than one strain. Again this introduces great uncertainty as to the prevalence and distribution of respective species from the different sample types. This is especially true when considering isolation of Campylobacter spp. causing disease in man as there is no certainty that the selected isolate is that which was responsible for disease. The incorporation of antibiotics into the isolation media not only introduces the issue of species bias but perhaps more importantly exposes the Campylobacter spp. to a cocktail of antibiotics thereby providing the potential for them to 'switch on' antibiotic resistance mechanisms. It might be argued that this has always been the case for isolation of Campylobacter spp., however, we know that the antibiotic cocktails used in media over the last 10 years have changed and indeed there was a time when the filtration protocol which didn't use antibiotics was more widely used. As most reports in the literature do not state what methods were used to isolate Campylobacter spp. it is not possible to quantify any relationship between antibiotics used in the isolation media and susceptibility data. An approved method for Campylobacter susceptibility testing was not available until May 2002, all data generated prior to this date will have been generated using non-standard methods. As tremendous variability in the reproducibility data for Campylobacter spp. was observed during the development of the standard agar dilution susceptibility method, data generated with disk diffusion and broth microdilution methods must be considered with caution. It has been shown that, compared with the conventional agar dilution method, the E-test tends to give rise to lower minimal inhibitory concentrations (MICs) for sensitive strains and higher MICs for resistant strains. There are no recommended antibiotic breakpoint concentrations for Campylobacter spp. A breakpoint is used to separate sensitive from resistant strains of bacteria and is thus crucial to any discussion of antibiotic resistance. This discussion is further complicated by introduction of the terms microbiological and clinical breakpoints. While a microbiological breakpoint can be a useful parameter with regard to identifying resistance factors it cannot on its own be used to predict whether that bacteria will respond to treatment from an appropriate antibiotic. Predicting clinical response is a function of the clinical breakpoint which considers the pharmacokinetic profile of the antimicrobial compound, i.e. the concentration of the antimicrobial compound in the body and the MIC. The National Committee for Clinical Laboratory Standards (NCCLS) uses microbiological, pharmacokinetic and clinical data to establish breakpoints, without c and clinical data to establish breakpoints, without such considerations it is not possible to consider what is truly clinically sensitive and resistant. There are no reported studies that have systematically determined appropriate breakpoints for Campylobacter, there are data however, which relate MICs to clinical outcome. It is without dispute that microbiological resistance in Campylobacter spp. occurs as a result of mutation in the gyrA gene with single point mutations most frequently causing a four- to eightfold shift in the MIC. What is also clear is that if a high enough concentration of antimicrobial relative to MIC of the infecting organism can be achieved not only will the parent organism be killed but also the 'resistant' mutant. Considering the above and the concentrations of ciprofloxacin achieved in the gastro-intestinal tract it is not surprising that clinical cure can be demonstrated for organisms with an MIC of 32 microg ml(-1).

Animals↗
PubMed2006

Antimicrobial susceptibility patterns of thermotolerant Campylobacter strains isolated from food animals in Ethiopia.

Thermotolerant Campylobacter spp. are frequent causes of diarrhoea in humans worldwide mostly originating from poultry. It has been suggested that extensive veterinary use of antibiotics is largely responsible for resistance in human isolates. During a 4-month period from January to April 2004, 192 Campylobacter spp. were isolated from fecal samples of 485 healthy food animals. The in vitro susceptibility to 12 antibiotics was determined by the agar disk diffusion method. Among the 192 Campylobacter spp. isolated, 135 (70.3%) were identified to be C. jejuni, 51 (26.6%) were C. coli and 6 (3.1%) were C. lari. C. jejuni was the most prevalent species in chickens (80.8%) versus 16.2% C. coli and 3.0% C. lari. All isolates found in pigs were C. coli. All strains were sensitive to chloramphenicol and ciprofloxacin and all were resistant to cephalothin. More than 90% of the strains were sensitive to clindamycin, erythromycin, gentamicin, nalidixic acid, norfloxacin, streptomycin and tetracycline. Resistance was found against ampicillin in 20% and trimethoprim-sulphamethoxazole in 37.5%. Resistance was not statistically different among C. jejuni, C. coli and C. lari (p>0.05). Multidrug resistance to two or more drugs was detected in 14.5% of strains. In conclusion, the study showed that antimicrobial resistance is found only at relatively low frequencies for most antimicrobial agents tested except for ampicillin and trimethoprim-sulphamethoxazole. The low percentages of resistance to most antimicrobial agents tested in this study may be the result of low/no usage of these agents as a growth promoters or treatment in the Ethiopian animal farm setting. The detection of multidrug resistant isolates may pose a threat to humans and further limits therapeutic options.

Animals↗
PubMed2002

Linezolid-resistant Enterococcus faecium isolated from a patient without prior exposure to an oxazolidinone: report from the SENTRY Antimicrobial Surveillance Program.

A patient case report describes an Enterococcus faecium strain isolated from a blood culture that was resistant to linezolid (MIC, 8 microg/mL; G2576U mutation of 23S rRNA). Co-resistances were identified for vancomycin, ampicillin, macrolides, fluoroquinolones, chloramphenicol, rifampin, gentamicin (high-level), nitrofurantoin and trimethoprim/sulfamethoxazole. Etest (AB BIODISK, Solna, Sweden) and disk diffusion results also detected the oxazolidinone resistance pattern. Laboratories should be aware of the rare possibility of these strains occurring during linezolid therapy or spontaneously (this case) in contemporary practice, and have in vitro susceptibility methods available capable of detecting oxazolidinone resistance.

Acetamides↗
PubMed1984

Effect of hyperbaric oxyhelium gas on response of bacteria to antimicrobial agents in vitro.

Modern diving techniques can require the treatment of infection in an atmosphere of pressurized oxyhelium gas. The antibiotic susceptibility of 16 species and strains (eight genera) of gram-negative bacilli and 3 species and strains (two genera) of gram-positive cocci to each of 21 antimicrobial agents was assessed in air at atmospheric pressure and in oxyhelium gas at an absolute pressure of 7 bar (ca. 709 kPa). A disk diffusion technique was employed, and significantly different results were obtained in the two atmospheres. The effect of oxyhelium on diameters of growth inhibition varied significantly with the bacterium and with the antibiotic and was particularly marked with certain bacterium-antibiotic combinations. The gram-negative bacilli generally gave reduced zone diameters in oxyhelium, whereas the gram-positive cocci showed a mixture of effects.

Anti-Bacterial Agents↗
PubMed1984

Biological activity of 4-hydroxyisophthalic acid derivatives. II. Anilides with antimicrobial activity.

A series of 1,3 -bis-anilides of 4-hydroxyisophthalic acid was prepared and tested for antibacterial and antifungal activity. The prepared compounds (I-XVIII), of general structure (A), (Formula: see text) where Xn = H (I); 2-F (II); 3-F (III); 4-F (IV); 2-Cl (V); 3-Cl (VI); 4-Cl (VII); 2-Br (VIII); 3-Br (IX); 4-Br (X); 2-J (XI); 3-J (XII); 4-J (XIII); 2,5-Cl2 (XIV); 2,4-Br2 (XV); 2,3,4-Cl3 (XVI), 2,4,5-Cl3 (XVII); 2,4,6-Cl3 (XVIII), were investigated for the purpose of determining the effect of halogen-substitution on the aniline rings of (A). All of these compounds were prepared in satisfactory hield by reaction of 4-hydroxyisophthalic acid with the appropriate aromatic amine at 175 degrees for 3 hours. The 1,3-bis-anilides prepared in this investigation were screened for antimicrobial activity by a disk-diffusion assay (Kirby-Bauer modified). The organisms used were laboratory cultures of S. aureus, B. subtilis, B. anthracis, M. paratuberculosis 607, E. coli Bb, S. typhi, S. typhimurium, S. paratyphi B, Pr. vulgaris, Kl. pneumoniae, Ps. aeruginosa, C. albicans, and A. niger. The results of this investigation indicated that most of the 1,3-bis-(halogen-anilides) of 4-hydroxyisophthalic acid had little or no antifungal activity "in vitro", while showed significant activity against Gram+ and Gram- bacteria. Some fluoro-derivatives showed inhibitory activity especially toward S. aureus and M. paratuberculosis. Iodo-derivatives showed broad-spectrum "in vitro" antimicrobial activity, and had some antifungal activity.

Anilides↗
PubMed1994

[Multi-center evaluation of Showa ceftizoxime disk susceptibility test to discriminate between the strains of methicillin-resistant Staphylococcus aureus (MRSA) and those susceptible (MSSA)].

An increasing prevalence of methicillin-resistant Staphylococcus (S.) aureus (MRSA) has a serious therapeutic problem, and accurate methods to detect such strains are needed. We studied the antimicrobial susceptibility of S. aureus to ceftizoxime, in comparison with those to four other cephems (cefazolin, cefoxitin, latamoxef and cefmenoxime), by broth microdilutions and disk susceptibility tests, and also evaluated whether the reagents, in replace of penicillinase-resistant penicillins (PRPs), could discriminate between the strains of MRSA and those susceptible to PRPs (MSSA). A total of 651 clinical isolates of S. aureus were collected from six geographically different hospitals. All the strains collected were first classified into either MRSA (n = 329) or MSSA (n = 322) according to the interpretations of MRSA screening agar, minimum inhibitory concentrations (MICs) to oxacillin and methicillin (NCCLS M7-A2), and the presence or absence of mecA gene by polymerase chain reaction. In broth microdilution tests, the MICs of MRSA to ceftizoxime ranged > or = 64 micrograms/ml, whereas all the MSSA were at the concentration of < or = 16 micrograms/ml. The results of Showa disk diffusion tests highly correlated with those of MIC determinations. The distribution of inhibitory zone diameters to ceftizoxime were clearly divided into two groups; 99.2% (sensitivity) of MRSA had inhibitory zones of < or = 20 mm and 98.9% (specificity) of MSSA produced > or = 21 mm. It was concluded that the Showa ceftizoxime disk susceptibility test was useful and enough reliable to screen MRSA isolates in clinical laboratories.

Ceftizoxime↗