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PubMed1979

Comparative penetration of various cephalosporins into inflammatory exudate.

A rabbit sterile peritonitis model was used to determine the relative penetration of four cephalosporin antibiotics into exudate fluid. Male New Zealand white rabbits were given 120 ml of sterile saline intraperitoneally, and peritonitis developed over the following 8 h, with exudate fluid containing a mean of 17,188 granulocytes per mm(3) at 8 h. Each antibiotic was administered intramuscularly at a dose of 30 mg/kg 3 h after peritonitis was initiated, and serum and peritoneal concentrations were measured 0.5, 1, 2, and 4 h later. Cefamandole gave the highest mean peak serum level (26.8 mug/ml), and cephalothin, cephacetrile, and cephradine all gave peak serum levels between 13 and 15 mug/ml. When peak peritoneal exudate concentration was expressed as a percentage of peak serum concentration, cephradine developed 28.5% of the peak serum level, cephacetrile 27.7%, cephalothin 14.0%, and cefamandole 12.5%. These percentages of exudate penetration were inversely proportional to the degree of serum protein binding: cephradine 26.6%, cephacetrile 36.3%, cephalothin 50%, and cefamandole 88%.

Animals↗
PubMed1979

Emergence of resistance to cefamandole: possible role of cefoxitin-inducible beta-lactamases.

Selection of resistance to cefamandole has been observed, and the drug has failed to protect animals lethally infected with certain Enterobacteriaceae that appeared to be highly susceptible in vitro. Using spectrophotometric assays, some of these organisms were found to produce beta-lactamases highly active against cefamandole. Cefoxitin, a poor enzyme substrate, was found to be superior to both cephalothin and cefamandole in induction of these enzymes. A simple disk induction test was developed and used to examine 147 Enterobacteriaceae for production of these beta-lactamases. The enzymes were found in 69% of cephalothin-resistant, cefamandole-susceptible strains and in only 3% of strains susceptible to both cephalothin and cefamandole. They were most prevalent among isolates of Enterobacter, indole-positive Proteus, and Serratia. Since selection of resistance and therapeutic failures have occurred most often among these genera, the relationship between presence of inducible enzymes and outcome of therapy should be examined further in humans.

Cefamandole↗
PubMed1979

Antibiotic activity in vitro against methicillin-resistant Staphylococcus epidermidis and therapy of an experimental infection.

Staphylococcus epidermidis is a major pathogen in early prosthetic valve endocarditis and cerebrospinal fluid shunt infections. Approximately 10 to 15% of hospital isolates are methicillin resistant. Ten clinically significant isolates of the latter were collected for antibiotic studies in vitro and in an experimental infection in animals. Time-kill studies of five strains showed gentamicin to be the single most effective antibiotic; however, dwarf colony variants emerged as survivors with two of these strains when challenged with gentamicin alone. The addition of a second antibiotic to gentamicin did not significantly improve the bactericidal rate but prevented the emergence of variant strains. A blood culture isolate of methicillin-resistant S. epidermidis combined with 5% hog gastric mucin was used to establish an experimental intraperitoneal infection in mice. Neither methicillin nor nafcillin treatment reduced mortality below that of untreated animals. Cephalothin treatment delayed early mortality but did not diminish overall mortality. Gentamicin was the most effective single antibiotic, and gentamicin in combination with vancomycin was the most effective regimen overall. The combination of rifampin plus vancomycin was as effective as gentamicin alone. The combinations of cephalothin or nafcillin with gentamicin and cephalothin with vancomycin demonstrated antagonism. The antagonism was not due to multiple injections or drug-drug inactivation.

Animals↗
PubMed1979

Inactivation of cephalosporins by Bacteroides.

We investigated the relationship between beta-lactamases of Bacteroides fragilis organisms and their resistance to cephalosporins. Timed killing curves were used to study the in vitro activity of three cephalosporins, cephalothin, cefazolin, and cefamandole, and a semisynthetic cephamycin, cefoxitin. Measurements of residual antibiotic concentrations in culture supernatants were made, and they were compared with the beta-lactamase activity of the microorganism. A cephalosporin-susceptible strain was rapidly killed by cephalothin, cefazolin, cefamandole, and cefoxitin. Four cephalosporin-resistant strains were not killed by cephalothin, cefazolin, or cefamandole but were killed by cefoxitin. An inoculum effect was noted with cefazolin and not with cefoxitin. The resistant strains of Bacteroides inactivated the three cephalosporins, but there was no inactivation of cefoxitin. A constitutive beta-lactamase was detected in all the isolates of the B. fragilis group that were resistant to the cephalosporins. There was no distinction of the species based on isoelectric focusing of the enzyme. These data suggest that inactivation by beta-lactamase may be the mechanism for resistance of B. fragilis to the cephalosporins and would explain the enhanced in vitro activity of cefoxitin.

Bacteroides↗
PubMed1979

Comparison of activity and beta-lactamase stability of cefotaxime with those of six other cephalosporins.

A study of the susceptibility to cefotaxime and six other cephalosporins in 213 nonselected strains of nine different bacterial species clearly showed that cefotaxime was the most active against aerobic gram-negative bacilli. The same pattern emerged with 84 cephalothin-resistant strains of five enterobacterial species, but the mean minimal inhibitory concentration values for all cephalosporins were about twofold higher in this group of strains. Cephalothin was the most active antibiotic against Staphylococcus aureus. The inoculus effect of 10 cephalothin-resistant strains was relatively small, but it was most marked for cefamandole, as compared with that of three other new cephalosporins, including cefotaxime. The susceptibility of these cephalosporins to beta-lactamases from 12 beta-lactamase-producing enterobacterial strains was determined. Half of these were slightly active against cefotaxime and had similar activity against cefuroxime. Cefoxitin was not degraded at all, and cefamandole was the most susceptible. No correlation between beta-lactamase susceptibility and minimal inhibitory concentration values of different cephalosporins was found. Cefotaxime combined high intrinsic antibiotic activity with marked resistance to beta-lactamase inactivation.

Bacteria↗
PubMed1987

Disk diffusion susceptibility testing of Branhamella catarrhalis with ampicillin and seven other antimicrobial agents.

A total of 74 clinical isolates of Branhamella catarrhalis were characterized with respect to their ampicillin, amoxicillin-clavulanate, cephalothin, cefaclor, erythromycin, tetracycline, chloramphenicol, and trimethoprim-sulfamethoxazole MICs and zones of inhibition. Disk diffusion tests were performed according to the guidelines of the National Committee for Clinical Laboratory Standards with two different media (Mueller-Hinton agar and chocolate Mueller-Hinton agar) and plates incubated under two atmospheric conditions (ambient air and 5 to 7% CO2). Optimum disk diffusion test results were obtained with Mueller-Hinton agar plates incubated in ambient air with all eight antimicrobial agents. On the basis of comparisons of MICs versus zones of inhibition, the following zone diameter interpretive criteria were defined for testing B. catarrhalis with disks containing 10 micrograms of ampicillin: greater than or equal to 38 mm, susceptible; 20 to 37 mm, moderately susceptible; less than or equal to 19 mm, resistant. The respective MIC correlates were less than or equal to 0.06, 0.125 to 0.5, and greater than or equal to 1.0 micrograms/ml. Because of the absence of frankly resistant test organisms, it was not possible to make definitive recommendations pertaining to disk diffusion tests with amoxicillin-clavulanate, cephalothin, cefaclor, erythromycin, tetracycline, chloramphenicol, and trimethoprim-sulfamethoxazole. Evidence is presented, however, which suggests that the current National Committee for Clinical Laboratory Standards disk diffusion interpretive criteria for nonfastidious bacteria can be applied to B. catarrhalis, at least as they pertain to the susceptible category with cephalothin, amoxicillin-clavulanate, erythromycin, tetracycline, chloramphenicol, and trimethoprim-sulfamethoxazole. With cefaclor, a zone diameter of greater than or equal to 21 mm was determined to adequately define the susceptible category.

Ampicillin↗
PubMed1988

Mechanism of action of cephalosporins and resistance caused by decreased affinity for penicillin-binding proteins in Bacteroides fragilis.

The susceptibilities of 52 clinical isolates of Bacteroides fragilis to five monoanionic cephalosporins were examined. Cefoperazone showed the highest antibacterial activity, followed by ceftezole, cefazolin, cefamandole, and cephalothin. There were two groups of resistant strains: one group (ca. 15%), of which B. fragilis G-232 was a typical sample, was resistant to ceftezole (MIC, 100 micrograms/ml), cefazolin (MIC, 100 micrograms/ml), and cephalothin (MIC, 200 micrograms/ml) but not cefoperazone (MIC, 6.25 micrograms/ml) or cefamandole (MIC, 25 micrograms/ml). On the basis of studies of stability to beta-lactamase, outer membrane permeation, and affinity for penicillin-binding proteins (PBPs), we conclude that decreased affinity for PBP 3 may play an important role in the resistance to ceftezole, cefazolin, and cephalothin in B. fragilis G-232. Another group (also ca. 15%), of which B. fragilis G-242 was a representative, was resistant to all five cephalosporins (MIC, 100 to 400 micrograms/ml) and produced a high amount of beta-lactamase. Similar broad-spectrum resistance was seen in a mutant of strain G-232 that had a greater-than-30-fold increase in beta-lactamase production.

Bacterial Proteins↗
PubMed1988

Comparative toxicities of cephalosporin antibiotics in a rabbit kidney cell line (LLC-RK1).

The rabbit kidney cell line LLC-RK1 was tested for its ability to discriminate the toxicities of six cephalosporin antibiotics according to their in vivo nephrotoxic potentials in rabbits. With the exception of cephalothin, which was markedly toxic to kidney cells in vitro, a good correlation between in vitro toxicity and in vivo nephrotoxicity was obtained, yielding the following toxicity rank order: ceftazidime less than cefazolin approximately cefoperazone less than cephaloglycin approximately cephaloridine. The addition of a kidney microsomal S9 fraction to the cell cultures desacetylated cephalothin as occurs in vivo and detoxified this antibiotic, providing it with the proper toxicity relative to the other cephalosporins. When compared with parent structures, desacetylated derivatives of other cephalosporins such as cephapirin were similarly found to be less toxic to LLC-RK1 cells. The acetylated cephalosporin cephaloglycin was not detoxified by the kidney S9 fraction and was desacetylated three to four times slower than cephalothin by renal esterases. Thus, the rate and extent of desacetylation of cephalosporins may play a role in their in vivo nephrotoxic potential. Our results further suggest that LLC-RK1 cells will provide a useful model for evaluating the potential nephrotoxicity of new cephalosporin antibiotics before in vivo studies.

Animals↗
PubMed2001

Multidrug-resistant urinary tract isolates of Escherichia coli: prevalence and patient demographics in the United States in 2000.

Concurrent resistance to antimicrobials of different structural classes has arisen in a multitude of bacterial species and may complicate the therapeutic management of infections, including those of the urinary tract. To assess the current breadth of multidrug resistance among urinary isolates of Escherichia coli, the most prevalent pathogen contributing to these infections, all pertinent results in The Surveillance Network Database-USA from 1 January to 30 September 2000 were analyzed. Results were available for 38,835 urinary isolates of E. coli that had been tested against ampicillin, cephalothin, ciprofloxacin, nitrofurantoin, and trimethoprim-sulfamethoxazole. Of these isolates, 7.1% (2,763 of 38,835) were resistant to three or more agents and considered multidrug resistant. Among the multidrug-resistant isolates, 97.8% were resistant to ampicillin, 92.8% were resistant to trimethoprim-sulfamethoxazole, 86.6% were resistant to cephalothin, 38.8% were resistant to ciprofloxacin, and 7.7% were resistant to nitrofurantoin. The predominant phenotype among multidrug-resistant isolates (57.9%; 1,600 of 2,793) included resistance to ampicillin, cephalothin, and trimethoprim-sulfamethoxazole. This was the most common phenotype regardless of patient age, gender, or inpatient-outpatient status and in eight of the nine U.S. Bureau of the Census regions. Rates of multidrug resistance were demonstrated to be higher among males (10.4%) than females (6.6%), among patients > 65 years of age (8.7%) than patients < or = 17 (6.8%) and 18 to 65 (6.1%) years of age, and among inpatients (7.6%) than outpatients (6.9%). Regionally, the rates ranged from 4.3% in the West North Central region to 9.2% in the West South Central region. Given the current prevalence of multidrug resistance among urinary tract isolates of E. coli in the United States (7.1%), continued local, regional, and national surveillance is warranted.

Adolescent↗
PubMed1974

R factor-mediated and chromosomal resistance to ampicillin in Escherichia coli.

Sixty-four ampicillin-resistant strains of Escherichia coli were studied. Six characters were examined: (i) resistance to ampicillin, cephalothin, and carbenicillin, (ii) synergy between ampicillin and cloxacillin, (iii) level of beta-lactamase activity after osmotic shock, (iv) transferability of ampicillin resistance, (v) immunological characterization of the enzyme, and (vi) determination of substrate profiles. One class of strains was found in which synthesis of beta-lactamase is inferred to be plasmid mediated; these strains are highly resistant to ampicillin and carbenicillin, sensitive to cephalothin, do not show synergism between ampicillin and cloxacillin, and reveal a high enzymatic activity after osmotic shock. A second class is formed by strains for which beta-lactamase synthesis is inferred to be chromosomal; these strains present a low resistance level to ampicillin, are sensitive to carbenicillin and resistant to cephalothin, show a synergism between ampicillin and cloxacillin, and reveal a very low enzymatic activity after osmotic shock. These characters may be used to differentiate periplasmic and cell-bound beta-lactamases.

Ampicillin↗
PubMed1975

Susceptibility of clinical isolates of Enterobacteriaceae to BL-S640, a new oral cephalosporin.

The in vitro activity of BL-S640, a 7-(2-aryl-2-aminoacetamido)-3-(heterocyclic-thiomethyl) cephalosporin, was evaluated against 338 clinical isolates of Enterobacteriaceae in comparison with ampicillin, cephalothin, cefazolin, and cephalexin. Against Escherichia coli, BL-S640 was as active as cefazolin and more active than ampicillin, cephalothin, and cephalexin. BL-S640 was as effective as the other cephalosporins tested and far more active than ampicillin against Klebsiella and was more active than cephalexin against Proteus mirabilis and the indole-positive Proteus. The majority of Enterobacter, Serratia, and Citrobacter were resistant to ampicillin and all the cephalosporins tested. With rare exceptions, the zone of inhibition by the BL-S640 30-mug disk was either larger or the same as the zone obtained by the cephalothin 30-mug disk in the Kirby-Bauer disk susceptibility test.

Cephalosporins↗
PubMed1976

Activity of cefamandole and other cephalosporins against aerobic and anaerobic bacteria.

The activity of cefamandole was comparable to that of cephalothin, cefazolin, and cephaloridine against Staphylococcus aureus, Streptococcus pyogenes, and Diplococcus pneumoniae. In contrast, cefamandole was considerably more active than cephalothin, cefazolin, or cephaloridine against gram-negative facultative bacilli, including Haemophilus influenzae, the most striking disparities being noted with indole-positive Proteus and Enterobacter. Bacteroides fragilis was more susceptible to cefoxitin than to cefamandole or cefazolin (median minimal inhibitory concentration, approximately 8, 32, and 32 mug/ml, respectively); cephalothin exhibited still less activity against this species. The majority of other anaerobes were inhibited by relatively low concentrations of all four cephalosporins. The results indicate a potentially valuable role for cefamandole against facultative gram-negative bacilli, including H. influenzae, but no exceptional activity against anaerobes.

Aerobiosis↗
PubMed1989

Susceptibility of Rhodobacter sphaeroides to beta-lactam antibiotics: isolation and characterization of a periplasmic beta-lactamase (cephalosporinase).

Thirteen strains of the gram-negative, facultative phototrophic bacterium Rhodobacter sphaeroides were examined fro susceptibility to beta-lactam antibiotics. All strains were sensitive to the semisynthetic penicillins ampicillin, carbenicillin, oxacillin, cloxacillin, and methicillin, but 10 of the 13 strains were resistant to penicillin G, as well as a number of cephalosporins, such as cephalothin, cephapirin, and cephalosporin C. A beta-lactamase (EC 3.5.2.6) with strong cephalosporinase activity was detected in all of the resistant strains of R. sphaeroides. With strain Y-1 as a model, it was shown that the beta-lactamase was inducible by penicillin G, cephalosporin C, cephalothin, and to some minor extent, cephapirin. The beta-lactamase was located in the periplasmic space, from which it could be extracted by osmotic shock disruption. By using this fraction, the beta-lactamase was purified 34-fold to homogeneity by steps involving batch adsorption to and elution from DEAE-Sephadex A50, chromatography on Q-Sepharose, and preparative polyacrylamide gel electrophoresis. The molecular masses of the native and denatured enzymes were determined to be 38.5 kilodaltons by gel filtration and 40.5 kilodaltons by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, respectively, indicating a monomeric structure. The isoelectric point was estimated to be at pH 4.3. In Tris hydrochloride buffer, optimum enzyme activity was measured at pH 8.5. The beta-lactamase showed high activity in the presence of the substrates cephalothin, cephapirin, cephalosporin C, and penicillin G, for which the apparent Km values were 144, 100, 65, and 110 microM, respectively. Cephalexin, cepharidine, and cephaloridine were poor substrates. The beta-lactamase was strongly inhibited by cloxacillin and oxacillin but only slightly inhibited by phenylmethylsulfonyl fluoride or thiol reagents such as iodoacetate and p-chloromercuribenzoate.

Anti-Bacterial Agents↗
PubMed1983

Medium-dependent zone size discrepancies associated with susceptibility testing of group D streptococci against various cephalosporins.

Mueller-Hinton (MH) agar media from various commercial sources, either supplemented or not supplemented with 5% sheep blood, were studied to determine their effect on disk diffusion susceptibility testing results obtained with 90 strains of group D streptococci and four cephalosporins. The cephalosporins investigated included cephalothin, cefamandole, moxalactam, and cefotaxime. Results showed that a number of Streptococcus faecalis and Streptococcus faecium strains were susceptible to cephalothin, cefamandole, and cefotaxime, but the number varied with both the commercial source and blood content of the MH medium used. Regardless of the MH medium used, none of the S. faecalis or S. faecium strains were found to be susceptible to moxalactam. The apparently medium-associated variations in the number of strains susceptible to cephalothin, cefamandole, and cefotaxime were largely due to minor discrepancies (one result being intermediate) among the various types of MH media used. However, major discrepancies (one result being resistant and the other susceptible or vice versa) were observed when S. faecalis strains were tested against cefotaxime. These major discrepancies were associated with both the commercial source of the MH medium and the blood content of the medium.

Cephalosporins↗
PubMed1983

Interlaboratory variation of antibiograms of methicillin-resistant and methicillin-susceptible Staphylococcus aureus strains with conventional and commercial testing systems.

Laboratory-prepared (conventional) and commercial susceptibility testing systems were compared by using a group of methicillin-resistant (MR) and methicillin-susceptible (MS) strains of Staphylococcus aureus. A group of 25 MR and 15 MS S. aureus strains were coded and tested blindly by disk diffusion, agar dilution, broth microdilution, Sensititre, Micro-Media, Sceptor, API 3600S, MicroScan, Autobac I, and MS-2 systems. All systems were incubated at 35 degrees C and read with either a manual or automated reader at the recommended times. Where applicable, systems were also read at 48 h. Among the conventional assays, the broth and agar dilution methods were comparable, both detecting 88% of the MR strains at 24 h and detecting 92 and 96%, respectively, at 48 h. The disk diffusion method was less efficient, detecting only 36 and 72% at 24 and 48 h, respectively. Detection of cephalothin resistance was low for all systems at both time periods, with agar dilution and disk diffusion being the most and least efficient, respectively. Some variability was also seen with detection of resistance to clindamycin and gentamicin. Among the MS strains, variability among the conventional systems occurred with methicillin, gentamicin, ampicillin, and penicillin. Comparison of the commercial systems with manual readers with the broth microdilution method (reference method) showed that for MR strains, the Sceptor system gave identical results at 24 and 48 h. Sensititre detected 68 and 88% of the MR strains, whereas Micro-Media was least effective detecting 12 and 80% at 24 and 48 h, respectively. None of the commercial systems detected cephalothin resistance well, with only one strain being indicated by the Sceptor and Sensititre systems at 48 h. Slight differences were also seen among the systems with clindamycin and gentamicin. With regard to the MS strains, variability among the systems was seen with methicillin, penicillin, ampicillin, clindamycin, and gentamicin. Among commercial systems with automated readers, the API system detected a greater number of MR strains than did the reference method at 24 and 48 h, 96 and 100%, respectively. The MicroScan method was comparable to the reference method detecting 80 and 88% of the MR strains at both time periods, respectively. Both Autobac I and MS-2 were much less effective in detecting MR strains, noting only 32 and 16%, respectively, at the 3- to 6-h readings. Poor detection of cephalothin resistance among MR strains was evident in all systems. Variability also occurred among the systems with clindamycin, gentamicin, and ampicillin. A single strain of the MR group was reported to be vancomycin resistant by the API system. Among the MS group, the greatest variability was seen with methicillin. Less variability occurred with penicillin, ampicillin, gentamicin, and vancomycin.

Humans↗
PubMed1989

Isolation and characterization of catalase-negative and catalase-weak strains of Campylobacter species, including "Campylobacter upsaliensis," from humans with gastroenteritis.

During 1987 and 1988, nine strains of catalase-negative or -weak Campylobacter species were isolated in Alberta, Canada. DNA hybridization studies demonstrated that seven strains were "Campylobacter upsaliensis," one strain was highly homologous with Campylobacter jejuni DNA, and one strain was a campylobacter unrelated to the other two species. All "C. upsaliensis" strains were hippurate negative, and six of seven were susceptible to cephalothin. The unusual variant of C. jejuni was hippurate positive and cephalothin resistant, whereas the unclassified strain was hippurate negative and resistant to intermediate levels of cephalothin. All patients from whom "C. upsaliensis" was isolated had diarrhea. Five of the patients were children two years old or younger, and two were adults. In this study, all catalase-negative and -weak strains were isolated from stool specimens by using a charcoal-based selective medium containing 32 micrograms of cefaperazone per ml and which was described by Hutchinson and Bolton (D. N. Hutchinson and F. J. Bolton, J. Clin. Pathol. 37:956-957, 1984).

Adult↗
PubMed1991

Campylobacter butzleri sp. nov. isolated from humans and animals with diarrheal illness.

Seventy-eight aerotolerant Campylobacter isolates were characterized phenotypically and by DNA hybridization (hydroxyapatite method at 50 and 65 degrees C). Two DNA relatedness groups were found. (i) Sixty-four strains belonged to aerotolerant Campylobacter DNA hybridization group 2. These organisms were isolated from humans, primarily with diarrheal illness, and animals on several continents. Strains were aerotolerant at 30 and 36 degrees C and catalase negative or weakly catalase positive, grew in media containing glycine and on MacConkey agar, were susceptible to nalidixic acid, and were resistant to cephalothin. The name Campylobacter butzleri sp. nov. is proposed for this group. (ii) DNA hybridization group 1 consisted of the type strain of Campylobacter cryaerophila and 13 additional strains isolated from 10 animals outside the United States and from three humans within the United States. This group was genetically diverse; five strains were closely related to the type strain of C. cryaerophila (DNA hybridization group 1A), and eight strains were more closely related to one another (DNA hybridization group 1B). Strains in DNA hybridization group 1B were phenotypically diverse, with two of eight strains resembling C. cryaerophila. The seven strains from DNA hybridization groups 1A and 1B which resembled C. cryaerophila and the C. cryaerophila type strain were aerotolerant only at 30 degrees C and catalase positive, did not grow in glycine or on MacConkey agar, were generally susceptible to nalidixic acid, and were resistant to cephalothin. The remaining six strains of DNA hybridization group 1B phenotypically resembled C. butzleri; however, they were generally catalase positive and susceptible to nalidixic acid and cephalothin. DNA hybridization group 1B is not designated as a separate species at this time since it cannot, with certainty, be separated genetically from C. cryaerophila or phenotypically from C. butzleri.

Animals↗