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PubMed1975

Potent combinations of beta-lactam antibiotics using the beta-lactamase inhibition principle.

Several penicillins known to be stable to enterobacterial beta-lactamases were tested in combination with beta-lactamase-sensitive penicillins and cephalosporins in a turbidimetric system. Nafcillin was found to be the best beta-lactamase inhibitor amongst agents presently available commercially, but the related, new semi-synthetic penicillin BRL 1437 (2-isopropoxy-1-naphthylpenicillin) was consistently found to be superior. Using 103 ampicillin-resistant coliform bacilli and antibiotic levels achievable in urine, cephalothin or cephaloridine alone achieved long-term suppression of growth (greater than 20 h) of 16 and 13% of strains, respectively, while the additional presence of BRL 1437 suppressed growth for longer than 20 h of 81% of the remaining strains. Even where 'success' was not achieved according to these stringent criteria, regrowth was significantly delayed by the presence of BRL 1437. Suppression of growth for longer than 20 h by BRL 1437 plus cephalothin was achieved with all of the 46 Escherichia coli strains tested. Antibiotic combinations were also studied in an in vitro model which stimulates the hydrokinetic features of the urinary bladder. Suppression of the growth of two highly resistant E. coli strains was achieved in this system, for therapeutically acceptable periods of time, with combinations of cephalothin or cephaloridine with BRL 1437, but not nafcillin.

Ampicillin↗
PubMed1982

Quantitative analysis of beta-lactamase production of multiple resistance to beta-lactam antibiotics in clinical isolates of Escherichia coli.

A simple test of procedure is described for the rapid evaluation of beta-lactamase substrate profiles against all the clinically important beta-lactam antibiotics. By use of this method 100 clinical isolates of Escherichia coli were classified into four beta-lactamase types: TEM-like, 35; chromosomal-like, 56; others, 3; beta-lactamase-less, 6 strains. They were tested for their susceptibilities to cefuroxime, cefoxitin, cefamandole, cephalexin, cefazolin, cephaloridine, cephalothin, ampicillin, carbenicillin and kanamycin. The isolates of each of TEM-like and chromosomal-like beta-lactamase types showed a good correlation between the beta-lactamase activity and the minimum inhibitory concentration (MIC) determined by the agar dilution method and the least square line analysis; MIC = ax + b, where x is enzyme activity, and a and b are constants. TEM-like beta-lactamase increased the resistance to ampicillin and carbenicillin markedly and that to cephalothin, cephaloridine and cefamandole moderately. In contrast, chromosomal-like beta-lactamase increased the resistance to ampicillin, cephalexin and cephalothin only slightly.

Anti-Bacterial Agents↗
PubMed1990

In vitro activity of daptomycin against 297 staphylococcal isolates.

The in vitro activity of daptomycin against 297 clinical isolates of Staphylococcus aureus and S. epidermidis sensu strictu was compared with the activities of cephalothin, dicloxacillin, tobramycin, and vancomycin. Minimal inhibitory concentrations (MICs) were determined by an agar dilution method. Cephalothin and dicloxacillin showed the highest activity against S. aureus on a weight-for-weight basis, all isolates being inhibited by 0.5 mg/l or less of either agent. Cephalothin was somewhat more active against S. epidermidis than was dicloxacillin. Daptomycin and vancomycin exhibited high and similar activity against both S. aureus and S. epidermidis (MIC90% = 1 and 2 mg/l, respectively). Tobramycin was highly active against S. aureus, but the activity against S. epidermidis was greatly variable (MIC range less than or equal to 0.03 - greater than or equal to 16 mg/l). The activity of daptomycin was markedly influenced by the test medium; the MICs were generally 32 times higher when the isolates were tested on Iso-Sensitest agar than on Mueller-Hinton agar. Supplementation of Iso-Sensitest agar with increasing concentrations of calcium potentiated the activity of daptomycin substantially, the results obtained on Iso-Sensitest agar supplemented with 20 mg Ca2+/l being similar to those obtained on Mueller-Hinton agar.

Anti-Bacterial Agents↗
PubMed2002

Antimicrobial susceptibility of Actinobacillus pleuropneumoniae, Escherichia coli, and Salmonella choleraesuis recovered from Taiwanese swine.

Minimum inhibition concentrations (MICs) were determined for ampicillin, ceftiofur, cephalothin, chloramphenicol, enrofloxacin, gentamicin, lincomycin, lincospectin (lincomycin/spectinomycin), neomycin, premafloxacin, spectinomycin, sulfamethoxazole/trimethoprim, and tetracycline against a total of 180 isolates of Actinobacillus pleuropneumoniae, Escherichia coli, and Salmonella choleraesuis (60 each) clinically isolated from pigs on farms in Taiwan from 1994 to 1996. No more than 3 isolates per farm were used. Ceftiofur had the highest activity in vitro against isolates of A. pleuropneumoniae, E. coli, and S. choleraesuis, with MIC90 values of 0.03, 2, and 1 microg/ml, respectively. Premafloxacin was highly active against isolates of A. pleuropneumoniae, E. coli, and S. choleraesuis, with MIC90 values of 2, 8, and 0.5 microg/ml, respectively, which were lower than those with enrofloxacin (MIC90 8, 32, and 2 microg/ml, respectively). Neomycin was moderately active against A. pleuropneumoniae and E. coli, with MIC90 values of 8 and 64 microg/ml, respectively, but was inactive with S. choleraesuis. Gentamicin showed high activity against A. pleuropneumoniae (MIC90 of 2 microg/ml) but was only moderately active with E. coli and S. choleraesuis (MIC90 of 64 and 32 microg/ml). Cephalothin was highly active against isolates of A. pleuropneumoniae (MIC90 of 1 microg/ml) but was inactive with E. coli (MIC90 of 128 microg/ml). Lincomycin had moderate activity (MIC90 of 32 microg/ml) against A. pleuropneumoniae. Chloramphenicol, lincomycin, and tetracycline were inactive with E. coli and S. choleraesuis (MIC90 > 128 microg/ml). In conclusion, ceftiofur and premafloxacin were highly active against isolates of A. pleuropneumoniae, E. coli, and S. choleraesuis, enrofloxacin and gentamicin were highly to moderately active; cephalothin was highly active against A. pleuropneumoniae and moderately active against S. cholearesuis; chloramphenicol, lincomycin, and tetracycline were active only with A. pleuropneumoniae; neomycin was moderately active against A. pleuropneumoniae and E. coli. The other antimicrobials tested were inactive.

Actinobacillus Infections↗
PubMed2004

Effects of bovine lactoferrin hydrolysate on the in vitro antimicrobial susceptibility of Escherichia coli strains isolated from baby pigs.

OBJECTIVE: To determine the antibacterial activity of bovine lactoferrin hydrolysate (bLf-lysate) alone or in combination with other antimicrobials against antimicrobial-resistant Escherichia coli strains isolated from baby pigs. SAMPLE POPULATION: 3 clinical strains of E coli were isolated from baby pigs with severe diarrhea and designated as strains 9061, 9062, and 9065. PROCEDURE: The broth microdilution checkerboard and fractional inhibitory (or bactericidal) concentration index were used to evaluate the antibacterial effect elicited by bLf-lysate in combination with kanamycin, gentamicin, cephalothin, cefamandole, penicillin G, ampicillin, tetracycline, erythromycin, or rifampicin against the 3 strains of E coli. RESULTS: The 3 strains of E coli were susceptible to gentamicin and rifampicin but highly resistant to most of the other antimicrobials tested, except for strain 9061 that was also susceptible to cephalothin but intermediately inhibited by kanamycin and cefamandole. Synergistic growth-inhibitory activity was observed between bLf-lysate and gentamicin against 1 strain of E coli (strain 9062); synergistic bactericidal activity was found between bLf-lysate and rifampicin against all 3 strains of E coli. Moreover, partial synergy was observed between bLf-lysate and kanamycin, gentamicin, cephalothin, or cefamandole against the strains of E coli, but this partial synergistic activity was mostly seen against only 1 of the strains. Little interaction between bLf-lysate and tetracycline, ampicillin, penicillin G, or erythromycin was observed against the clinical strains of E coli. CONCLUSIONS AND CLINICAL RELEVANCE: A combination of bLf-lysate and certain antimicrobials may prove clinically effective against antimicrobial-resistant strains of E coli.

Animals↗
PubMed1976

Comparative in vitro activity of cephalosporins.

The in vitro activity of cephalexin, cephaloridine, cephalothin, cephapirin, cefoxitin, cephamycin C, cepharadine and cefazolin was determined against 443 isolates of bacteria. At a concentration of 12.5 mug/ml, all of the cephalosporins inhibited more than 60% of the isolates of Klebsiella pneumoniae. At the same concentration, cephalexin, cephaloridine, cephalothin, cephapirin, cephamycin C and cefazolin inhibited more than 90% of isolates of proteus mirabilis. All of the cephalosporins except cephalothin and cephapirin inhibited over 60% of isolates of Escherichia coli at a concentration of 12.5 mug/ml. Cefoxitin was the most active cephalosporin against gram-negative bacilli. There was substantial differences in the activity of cephalosporins against gram-positive cocci. Cephaloridine was the most active cephalosporin against these organisms. There was considerable fluctuation in the proportion of isolates of gram-negative bacilli susceptible to these cephalosporins from year to year, but there was no evidence to suggest that the number of resistant isolates was increasing.

Cephalosporins↗
PubMed2005

Enumeration and antibiotic resistance patterns of fecal indicator organisms isolated from migratory Canada geese (Branta canadensis).

Thermotolerant fecal indicator organisms carried by migratory waterfowl may serve as reservoirs of antibiotic resistance. To determine the extent to which such antibiotic resistance markers were present in migratory Canada geese (Branta canadensis) on the Maryland Eastern Shore, we isolated Enterococcus spp. and Escherichia coli from fresh feces and examined the antibiotic resistance profiles of these bacteria. Samples were obtained in October 2002, January 2003, and March 2003. Thermotolerant E. coli counts ranged from 0 to 1.0x10(7) colony forming units (CFU)/0.1g (g-1) wet weight of feces, whereas Enterococcus spp. counts ranged from 1.0x10(2)-1.0x10(7) CFU g-1 wet weight of feces. Primary isolates of each indicator organism were tested against a panel of 10 antibiotics. Greater than 95% of E. coli isolates were resistant to penicillin G, ampicillin, cephalothin, and sulfathiazole; no E. coli were resistant to ciprofloxacin. Enterococcal isolates showed highest resistance to cephalothin, streptomycin, and sulfathiazole; no enterococci were resistant to chloramphenicol. The tetracyclines, streptomycin, and gentamycin provided the greatest discrimination among E. coli isolates; chlortetracycline, cephalothin, and gentamycin resistance patterns provided the greatest discrimination between enterococcal strains. Multiple antibiotic resistance (MAR) profiles were calculated: fall (E. coli=0.499; enterococci=0.234), winter (E. coli=0.487; enterococci=0.389), and spring (E. coli=0.489; enterococci=0.348). E. faecalis and E. faecium, which are recognized human nosocomial pathogens, were cultured from winter (44 and 56%, respectively) and spring (13 and 31%, respectively) fecal samples.

Animal Migration↗
PubMed1994

Cefotetan-induced immune hemolytic anemia due to the drug-adsorption mechanism.

Positive direct antiglobulin tests (DATs) associated with cephalosporin therapy have been reported, but rarely were associated with immune hemolytic anemia (IHA). In 1989, we described the first case of IHA associated with cefotetan (Cefotantrade mark) causing hemolysis by the drug-adsorption mechanism. We now report the full details of ow investigation. The patient was a 23-year-old female with a 2 1/2 year history of chronic ulcerative colitis. After 4 days of therapy with cefotetan (2 g/day), her hematocrit (Hct) decreased from 34.351 to 23.3%. The reticulocyte count was 6.9%. The DAT was 2+ (IgG only), and the serum and an eluate were nonreactive with a panel of standard reagent red blood cells (RBCs). Cefotetan therapy continued and the patient was transfused with two units of RBCs. On day 6 of therapy, the patient experienced an anaphylactoid reaction attributed to sensitivity to cefotetan. Cefotetan therapy was discontinued, the patient was treated with corticosteroids and epinephrine, and she was transfused with an additional unit of RBCs. Her Hct rose to 34.1% prior to her discharge on day 11. Further investigation revealed that the patient's serum and an eluate contained an antibody that reacted with cefotetan- and cephalothin-coated RBCs by the indirect antiglobulin test. In a monocyte monolayer assay, monocytes readily phagocytized cefotetan- and cephalothin-coated reagent RBCs but not uncoated reagent RBCs. The patient's serum did not react by the so-called immune-complex mechanism when cefotetan or cephalothin was added to the patient's serum + complement + RBCs.

Journal Article↗
PubMed1989

[Antimicrobial sensitivity profile of Staphylococcus aureus at a pediatric hospital: prevalence of resistance to methicillin].

Methicillin-resistant Staphylococcus aureus (MRSA) has become a significant cause of nosocomial infections. In efforts to delineate the magnitude of this problem, we determined the prevalence of MRSA in community acquired (n = 382) and nosocomial strains (n = 207) of S. aureus isolated between Jan 1986 and March 1989. Antimicrobial susceptibility was evaluated using an agar dilution method (Muller-Hinton agar supplemented with 4% NaCl incubated to 35 degrees C for 24 h) and MIC breakpoints were determined according to NCCLS standards. We detected (24.2%) MRSA in nosocomial strains and (5%) MRSA in community acquired strains (P less than 0.05), with a global prevalence of 11.7%. The susceptibility of community acquired S. aureus was 90% or higher for dicloxacillin, cephalothin, sulbactam/ampicillin (S/A), clindamycin, rifampicin and amikacin; 85% for cefotaxime and SMX/TMP and only 75% for erythromycin. The susceptibility pattern of the nosocomial strains was consistent with the prevalence of MRSA but the susceptibility for cephalothin, amikacin and sulbactam/ampicillin was 84.4%, 89.4% and 86.5% respectively, significantly higher than for methicillin (P less than 0.05). Although the increased susceptibility for cephalothin and amikacin has been reported for MRSA before, the published reports using these antibiotics in the treatment of MRSA infections are controversial. The increased susceptibility of MRSA to S/A could be explained in part if the MR was mediated by "acquired MR" attributable to B-lactamase production. Our data provide a perspective on the magnitude of MRSA as a problem in a pediatric teaching hospital in Mexico. Moreover, if taken at face value, the in vitro susceptibility data point to various potential treatment options which warrant clinical evaluation.

Cross Infection↗
PubMed1979

Storage of microtiter plates for antimicrobial susceptibility tests.

Microdilution susceptibility tests are being performed routinely and in increasing numbers in many clinical laboratories. Microtiter plates for these assays are usually prepared in large batches and stored frozen until needed. Studies were performed to investigate the stability at -20C and at -70C of ampicillin, carbenicillin, ticarcillin, gentamicin, tobramycin, amikacin, chloramphenicol, and cephalothin, using Enterobacter aerogenes, Proteus mirabilis, Proteus vulgaris, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella as test organisms. The stability at -20C and -70C of clindamycin, vancomycin, cephalothin, cefazolin, oxacillin, methicillin, nafcillin, and penicillin was analyzed using Staphylococcus eureus, Staphylococcus epidermidis, Enterococcus, and alpha Streptococcus as the test organisms. No significant deterioration of any of the antibiotics was noted after ten weeks of storage at -70C, as detected by minimum inhibitory concentration determinations. No significant differences were noted at -20C for clindamycin, chloramphenicol, vancomycin, cefazolin, cephalothin, gentamicin, tobramycin, and amikacin. By ten weeks' storage at -20C, significant deterioration of carbenicillin, ticarcillin, ampicillin, penicillin, methicillin, oxacillin, and nafcillin was observed.

Anti-Bacterial Agents↗
PubMed1982

[Clinical laboratory approach for determination of effective dose of cefotiam. Observation from disc susceptibility test and MICs].

Reliability of cefotiam disc diffusion susceptibility test was investigated for determining whether the disc results correlate with minimal inhibitory concentration (MIC) or not. The results of Showa disc and Oxoid disc were well correlated. The inhibitory zone size of Showa disc and MIC were also well correlated, indicating reliability of the cefotiam disc test. The disc result, was observed over 84% of clinically isolated S. aureus, S. epidermidis, S. pneumoniae, S. pyogenes, E. coli, K. pneumoniae, P. mirabilis and H. influenzae. Their mean MICs were less than about 1.5 microgram/ml. Such a result should be useful for the determination of drug dose in various clinical conditions in order to obtain the proper drug levels in blood and tissues. The results of antibiotic disc diffusion susceptibility test with various bacteria isolated from clinical materials were compared. Cefotiam revealed a potent antimicrobial activity against Gram-positive cocci, showing a similar potency to that of cephalothin and cefazolin. However, it showed a stronger activity against Gram-negative bacilli than that of cephalothin, cefazolin, cephalexin and cefoxitin, revealing less resistant strains. Cephalosporins developed recently such as cefotaxime, cefoperazone, ceftizoxime, latamoxef etc. show very potent antimicrobial activity against Gram-negative bacilli, but their activity against S. aureus and S. epidermidis is weaker than that of cefotiam, cephalothin, cefazolin etc. Therefore, cefotiam can be considered as one of the drugs of first choice for surgical perioperative prophylaxis and blind therapy.

Bacteria↗
PubMed1980

Microorganisms isolated from blood and cerebrospinal fluid in a general hospital. Clinical implications.

This study is a review of 1,040 significant positive blood cultures from 415 patients, and 44 positive cerebrospinal fluid cultures from 44 patients treated at the Meir General Hospital during the period 1976-78. The most frequent isolates from blood cultures were Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae. The most frequent isolates from cerebrospinal fluid cultures were Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis, which were present in similar proportions. E. coli was predominant in the division of medicine, Staph. aureus in the division of pediatrics and Klebsiella in the division of surgery. Fifty percent of the E. coli isolates were sensitive to ampicillin and carbenicillin; about 80%, to cephalothin and sulfamethoxazole-trimethoprim; and 100%, to gentamicin. Only 7% of the Klebsiella isolates were sensitive to apicillin; 72% were sensitive to cephalothin and 87%, to gentamicin. Only 18% of Staph. aureus isolates were sensitive to penicillin, but about 95% were sensitive to methicillin or cephalothin. Two of 10 salmonellae isolates and 13% of H. influenzae were resistant to ampicillin.

Blood↗
PubMed1978

[Comparative studies on the action of aminoglycosides and cephalosporins on the proximal tubule of the human kidney (author's transl)].

Tubulo-toxic effects of drugs can be recognised by the elimination of portions of brush border membrane in the urine. An integral constituent of the brush border membrane is an alanine aminopeptidas (AAP). It is measurable in the urine enzymatically and immunologically with great reliability. The AAP activity was determined in the 24-hour urine of test subjects. Fifteen subjects received 3 mg/kg gentamicin, sisomicin or tobramycin on 3 consecutive days and 10 subjects were given amikacin (15 mg/kg). In addition, 15 subjects received cephacetrile (8.0 g), cephazolin (6.0 g) or cephalothin (8.0 g) on 3 consecutive days. It was shown that all aminoglycosides have a cumulative effect on the brush border membrane, amikacin is the strongest and tobramycin the weakest. The cephalosporins cephalothin and cephazolin were indifferent to the tubule membranes and had no effect on the excretion of AAP. There were responders and non-responders to cephacetrile. The application of cephalothin and cephazolin immediately before the administration of gentamicin prevents the membrane effect of gentamicin.

Adolescent↗
PubMed1980

The in vitro activity of cefamandole against 3312 bacterial isolates. A Norwegian multicentre study.

In a multicentre study the in vitro activity of cefamandole against 3312 bacterial isolates was compared to the antibacterial activity of cephalothin, ampicillin, oxacillin, doxycycline and tobramycin. Cefamandole and tobramycin showed the highest activity against the Enterobacteriaceae isolates, whereas the Staphylococcus aureus isolates were slightly less sensitive to cefamandole than to cephalothin and oxacillin. There was no significant difference between the activity of cephalothin and cefamandole against the isolates of Haemophilus influenzae and enterococci.

Anti-Bacterial Agents↗
PubMed1995

Antibiotic resistance of Vibrio anguillarum, in relation to serovar and plasmid contents.

A total of 520 Vibrio anguillarum strains, isolated from fish and the environment, were tested for their sensitivity to 20 different antibiotics. Most isolates were of European origin. The results were compared with data on the O-serogroup and plasmid contents. All strains were sensitive to neomycin, spectinomycin, nitrofurantoin, flumequine and oxolinic acid, while most strains were sensitive to streptomycin, oxytetracycline, chloramphenicol, sulphonamides, trimethoprim, sulphonamides with trimethoprim, nalidixan, rifampicin, novobiocin and O/129. A major part of the strains were resistant to the macrolides, spiramycin and lincomycin. For ampicillin, cephalothin, and colistin marked differences were recorded with respect to O-serogroup. Most O1 strains were resistant to colistin and sensitive to ampicillin and cephalothin, while most O2 strains were sensitive to colistin but resistant to ampicillin and cephalothin. Some antibiotic resistant strains carried plasmids but no conjugation experiments were carried out to detect possible R factors.

DNA↗
PubMed1994

[Microbial drug resistance and the presence of plasmids in Salmonella strains isolated from different sources].

BACKGROUND: To establish the relationship between the presence of plasmid and their antimicrobial resistance of Salmonella strains. METHODS: We tested 171 strains of Salmonella isolated from different sources: natural waters (73 strains), food (23 strains), and from clinical samples (75 strains). The disk diffusion method was used to test the antimicrobial susceptibility of the strains to 13 drugs. Plasmid analysis were performed by agarose gel electrophoresis technique. RESULTS: Antimicrobial resistances of the strains significantly varies according to their primary isolation sources. Strains isolated from the water environment exhibited a full susceptibility to cephalothin and colistin, whilst all the strains isolated from food were sensitive to ampicillin, gentamicin, kanamycin, neomycin, tobramycin and trimethoprim-sulphamethoxazole. On the other hand, resistances to colistin, gentamicin and trimethoprim-sulphamethoxazole were not found in clinical isolates. From the 171 Salmonella strains tested, only 12.2% were sensitive to all the antimicrobials. The most frequently antibiotic resistances detected were to streptomycin (49.3%), tetracycline (33.1%) and nalidixic acid (30.7%). The percentage of strains that harboured plasmids was different depending on the source of isolation, ranging from 41.4% for water isolated, 76% for clinical isolates and 86.9% for food isolates. The relationship between antimicrobial resistance and plasmid presence is very close, since higher percentages of resistance to chloramphenicol, carbenicillin, cephalothin, kanamycin, neomycin, nalidixic acid and trimethoprim-sulphamethoxazole were obtained in strains containing plasmids. CONCLUSIONS: (a) The most frequently resistance detected in strains of Salmonella was to streptomycin (49.3% of the strains). On the other hand, only 0.6% of the strains were resistant to gentamicin. (b) Percentages of resistance to some antibiotics was higher in strains harbouring plasmids, that implies a relationship between the plasmid presence and the antibiotic resistance in Salmonella. (c) Curing of extrachromosomic elements by acridine orange showed a percentage of resistance lost greater than 70% for cephalothin, kanamycin, neomycin, and nalidixic acid. This indicates that the resistance to those antibiotics is mainly linked to plasmids. In the case of the unusual nalidixic acid-resistance, previously described in Shigella strains, suggests that are needed more studies to demonstrate the direct association between antimicrobial resistance and presence of plasmids.

Anti-Bacterial Agents↗
PubMed1994

Gram negative bacteria isolated from blood cultures in a general hospital.

This study reviews 2205 significant positive blood cultures from 534 patients treated at the Meir General Hospital during the period 1988-1990. In addition, a comparison was made with a previous survey performed twelve years ago (1976-1978). Gram negative rods accounted for 68% of the septicemia cases indicating a small increase since the former survey (61.2%). The order of Gram negative frequencies was E. coli, Urea positive Gram negative bacteria (UPGNB) Klebsiella, Enterobacter, Pseudomonas (in a decreasing order). E. coli was most predominant in both surveys in the internal wards while UPGNB were predominant in the geriatric-rehabilitation wards. A significant rise in frequency of cephalothin and sulfamethoxazole-trimethoprim resistant E. coli isolates was noticed. In UPGNB, Klebsiella and Pseudomonas a significant increase in resistant isolates to cephalothin, gentamicin, sulfamethoxazole-trimethoprim and chloramphenicol was found. As for tobramycin, amikacin and mezlocillin, it is clear that the Gram negative bacteria have gained resistance to these drugs over recent years. Resistance frequencies of above 20% were found in Enterobacter and Pseudomonas for the newer antimicrobial agents such as: ceftriaxone, cefotaxime or ceftazidime. Low resistance is still seen in all above bacteria against ciprofloxacin and ofloxacin. The minimal inhibitory concentrations (M.I.C.) of gentamicin, cephalothin, cefotaxime, ceftazidime ceftriaxone and sulfamethoxazole-trimethoprim do not exceed the range of 30 micrograms/ml. The M.I.C. range of the quinolone ciprofloxacin does not exceed 6 micrograms/ml.

Drug Resistance, Microbial↗
PubMed1993

[Isolation of antibiotic-resistant Escherichia coli from the water of the Río de la Plata].

Water of a recreational zone of the Río de la Plata was analyzed. Levels of total heterotrophic bacteria ranged from 1.5 x 10(3) to 6.2 x 10(3) CFU/ml and total coliforms were between 5.0 x 10(2) and 7.0 x 10(3) per 100 ml. Values of fecal coliforms were between 1.0 x 10(2) and 1.3 x 10(3) per 100 ml. Among 131 E. coli strains isolated, 20.6% of cephalothin resistance was found, followed by nitrofurantoin, ampicillin, sulfisoxazole and the trimethoprim sulfamethoxazole combination. Resistance to more than one antibiotic was found in 36.7% of the strains isolated and 9.2% were resistant to three or more antibiotics. Three strains resistant to four antibiotics and one resistant to five were isolated. The highest percentage of combined resistance occurred for the pairs cephalothin-nitrofurantoin and cephalothin-ampicillin.

Argentina↗