Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Enterobacter”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources
PubMed1987

Comparison of difloxacin, enoxacin, and cefoperazone for treatment of experimental Enterobacter aerogenes endocarditis.

This study compared difloxacin administered orally, enoxacin administered orally, and cefoperazone administered intramuscularly for the treatment of experimental Enterobacter aerogenes endocarditis. Difloxacin significantly reduced bacterial counts of vegetations, as compared with enoxacin and cefoperazone. Enoxacin and cefoperazone did not differ significantly. This study demonstrated that difloxacin was significantly more effective than enoxacin and cefoperazone for the treatment of E. aerogenes endocarditis in rabbits.

Animals↗
PubMed1988

Protective effect of amdinocillin against emergence of resistance to ceftazidime in Enterobacter cloacae.

Enterobacter cloacae infections have been shown clinically to respond less reliably to monotherapy with broad-spectrum cephalosporins than was initially expected. Selection of populations producing high levels of beta-lactamase has been shown to be the most frequent reason for treatment failure, and the use of these agents with another active antibiotic is recommended. In this study, E. cloacae strains from clinical specimens susceptible to ceftazidime and amdinocillin by broth dilution and disk tests were examined. In the presence of ceftazidime at 10 micrograms/ml, in vitro selection of resistant organisms was demonstrated for 3 of 11 strains. Selection was prevented when amdinocillin was added in combination. A more rapid killing was also demonstrated with this combination. At inocula of 10(8) CFU/ml, ceftazidime-resistant populations were isolated from 6 of 11 strains in vitro, and the emergence of this resistance was prevented by amdinocillin. The enhanced killing effect noted for amdinocillin with ceftazidime may have resulted in part from complementary activity of the antibiotics on penicillin-binding proteins. The ceftazidime-amdinocillin combination offers an interesting prospect for the therapy of infections caused by E. cloacae strains which are initially susceptible to both antibiotics.

Amdinocillin↗
PubMed1989

ampG is essential for high-level expression of AmpC beta-lactamase in Enterobacter cloacae.

Mutants of Enterobacter cloacae 55 were studied to delineate more completely the genetics of inducible expression of AmpC beta-lactamase. E. cloacae 55M-L, derived by mutagenesis from a mutant with high-level cefotaxime resistance (MIC, greater than 64 micrograms/ml), E. cloacae 55M, demonstrated a novel phenotype by producing only low levels of AmpC constitutively. Neither the parental phenotype of E. cloacae 55M nor the wild-type phenotype of E. cloacae 55 could be restored in E. cloacae 55M-L by the introduction of functional ampR, ampC, or ampD genes. Cloning each of these genes from E. cloacae 55M-L confirmed the same genotype for this mutant as for its parental strain. Mutation of E. cloacae 55M-L to the E. cloacae 55M phenotype was found to occur spontaneously at a frequency of 10(-8). All such revertants demonstrated an inducible wild-type phenotype after introduction of a functional ampD. These results suggested that the E. cloacae 55M-L phenotype was due to a mutation in an as yet unrecognized gene, designated ampG. Verification of this gene was obtained by the restoration of the E. cloacae 55M phenotype in E. cloacae 55M-L by introduction of a cloned 2.9-kilobase BamHI fragment from the E. cloacae 55 chromosome. Transformation of both ampG and ampD into E. cloacae 55M-L reconstituted the inducible wild-type phenotype. These results indicate that ampG is required for the activation of ampC by AmpR. Without ampG, neither induction nor high-level expression of AmpC is possible. It is likely that the ampG gene product and AmpD together modulate the ability of AmpR to activate ampC expression.

Ampicillin↗
PubMed1989

Resistance emerging after pefloxacin therapy of experimental Enterobacter cloacae peritonitis.

Resistance emerging after pefloxacin therapy was investigated in an experimental Enterobacter cloacae infection. Mice were inoculated intraperitoneally (mean inoculum, 0.9 X 10(8) CFU) with one of four strains initially susceptible to quinolones and treated with a single 25-mg/kg dose of pefloxacin. This therapy produced a net decrease of bacterial counts in the peritoneal fluid, but with the of the isolates, posttherapy (PT1) strains emerged with decreased susceptibilities to quinolones (4- to 1,024-fold), to the structurally unrelated antibiotics (4- to 16-fold) chloramphenicol and trimethoprim, and sometimes to tetracycline and beta-lactam compounds. In a second set of experiments, new mice were similarly infected with PT1 strains and treated with up to five 25-mg/kg doses of pefloxacin. Compared with parent isolates, PT1 strains produced similar disease and peritoneal bacterial count in the control animals. In treated mice posttherapy (PT2) strains emerged that showed 8- to 64-fold increases in quinolone MICs compared with the PT1 strains inoculated. All PT1 and PT2 strains showed altered outer membrane protein patterns, principally marked by a decreased 37,000-molecular-weight band generally accompanied by an increased 42,000-molecular-weight band. Whole cells from all PT1 and PT2 strains, exposed to [14C]pefloxacin for 15 to 60 s, bound significantly less radioactivity than the corresponding parent strains. After partial purification, DNA gyrase extracted from the most resistant isolates (one PT1 and the PT2 strains) showed a 100- to 450-fold 50% inhibitory concentration increase for pefloxacin. Altogether, pefloxacin can select in vivo two types of resistant strain, one with only decreased permeability and another with decreased permeability combined with altered DNA gyrase.

Animals↗
PubMed1990

In vitro emergence of quinolone-resistant mutants of Escherichia coli, Enterobacter cloacae, and Serratia marcescens.

Norfloxacin- and ciprofloxacin-resistant mutants of several Enterobacter cloacae and Serratia marcescens isolates occurred at frequencies of greater than or equal to 10(-7)/CFU, which were higher than those of Escherichia coli isolates, in accordance with the increasing emergence of less-susceptible or resistant strains in clinical isolates of E. cloacae and S. marcescens.

Anti-Infective Agents↗
PubMed1991

Novel method for measurement of outer membrane permeability to new beta-lactams in intact Enterobacter cloacae cells.

The ability of five new beta-lactams to permeate the outer membrane of intact Enterobacter cloacae beta-lactamase-overproducing cells was measured by using a high-pressure liquid chromatography (HPLC)-based technique that avoided certain possible artifacts of the traditional methods. Low concentrations of antibiotics were mixed with bacterial suspensions, and at different times, the cells were removed from the medium by filtration. Residual beta-lactam concentrations in the medium were then assessed by HPLC and UV detection. The assay was performed under conditions in which no beta-lactamase activity was detected in the filtrate and the number of viable cells remained constant during the experiment. Outer membrane permeability was assessed with the Zimmermann-Rosselet equation, in which outer membrane permeability was rate limiting for hydrolysis of the beta-lactam by periplasmic beta-lactamase. Thus, the rate of disappearance of beta-lactam was equal to the rate of outer membrane permeation. Preincubation of bacterial suspensions with 300 micrograms of cloxacillin per ml inhibited the hydrolysis of beta-lactams by intact cells, demonstrating that beta-lactam hydrolysis by periplasmic beta-lactamase was essential in order to allow measurement of outer membrane permeability by this method. Permeability coefficients (P) were calculated from the Zimmermann-Rosselet equation and were independent of the external concentration of antibiotic over a 100-fold concentration range. Cefepime and cefpirome exhibited rates of outer membrane permeation 5- to 20-fold higher than those of carumonam, ceftriaxone, and cefotaxime. Thus, the presence of a positive charge in the 3-lateral chain increased the permeation ability of beta-lactam molecules considerably.

Anti-Bacterial Agents↗
PubMed1991

Reevaluation of the factors involved in the efficacy of new beta-lactams against Enterobacter cloacae.

The roles of outer membrane permeability, beta-lactamase stability, and inhibition of penicillin-binding proteins in the activity of new beta-lactams against Enterobacter cloacae were reappraised by using several methodological improvements. Outer membrane permeability in intact cells was determined by using a high-pressure liquid chromatography (HPLC)-based technique that avoided certain possible artifacts of the traditional methods. Vmax values were calculated from the numbers of enzyme molecules produced per cell and from catalytic constant (Kcat) values, which were obtained with purified beta-lactamase. Minimal periplasmic antibiotic concentrations needed to inhibit bacterial cell wall synthesis were estimated from the Zimmermann-Rosselet equation. All the beta-lactams tested formed relatively stable complexes with purified beta-lactamase. The antibiotics that exhibited low affinity for beta-lactamase apparently needed higher periplasmic concentrations to inhibit cell wall synthesis, suggesting a possible correlation between the affinity of beta-lactamase and the affinity of penicillin-binding proteins for the new beta-lactams. By using these estimates of outer membrane permeability, beta-lactamase hydrolysis, and cell wall-inhibiting concentrations, MIC could be theoretically predicted to within 1 dilution for five beta-lactams in three isogenic E. cloacae strains with differences in antibiotic susceptibility due to different porin or beta-lactamase contents.

Anti-Bacterial Agents↗
PubMed1991

Increased resistance to multiple drugs by introduction of the Enterobacter cloacae romA gene into OmpF porin-deficient mutants of Escherichia coli K-12.

Introduction of the romA gene cloned from Enterobacter cloacae into Escherichia coli K-12 resulted in almost complete inhibition of OmpF expression and a concomitant increase in resistance to quinolones, beta-lactams, chloramphenicol, and tetracyclines. In addition, the romA gene reduced the susceptibility to these multiple drugs even in the OmpF porin-deficient mutants of E. coli K-12. Results indicate the presence of romA-sensitive penetration pathway(s) for these multiple drugs other than the OmpF porin in E. coli.

Anti-Bacterial Agents↗
PubMed1991

Altered phenotypes associated with ampD mutations in Enterobacter cloacae.

A study was done to determine the genetic locus responsible for altered expression of AmpC beta-lactamase in Enterobacter cloacae 1194E and several mutants derived from E. cloacae 029. These phenotypes were defined by units of enzyme activity found in sonic extracts of cells before and after induction with cefoxitin and included (units uninduced/units induced) the wild-type (7/219), high-level constitutive (10,911/10,862), temperature-sensitive (at 30 degrees C 82/706 and at 42 degrees C 5,031/6,020), and hyperinducible (19/1,688) phenotypes. When the ampD region of each E. cloacae strain was cloned and introduced into an ampD mutant Escherichia coli strain, the altered phenotypes were found to reside within this locus. Furthermore, transformants containing wild-type ampD were poorly inducible at 42 degrees C while those with high-level constitutive or hyperinducible ampD were unaffected by temperature. Since the source of ampD was the only variable in these E. coli transformants, these results suggested that ampD encodes a protein that is involved in sensing the inducer. To test this possibility, the responses to different inducers of E. coli transformants containing various ampD regions were assessed. In the presence of wild-type ampD, transformants responded equally to cefoxitin and cefotetan, regardless of temperature. In the presence of temperature-sensitive ampD, induction by cefotetan was similar to that by cefoxitin at 30 degrees C but greater than that by cefoxitin at 42 degrees C. These results suggest that ampD encodes a protein involved in induction of AmpC beta-lactamase in E. cloacae.

Anti-Bacterial Agents↗
PubMed1991

Association of two resistance mechanisms in a clinical isolate of Enterobacter cloacae with high-level resistance to imipenem.

Carbapenem resistance was studied in a clinical isolate of Enterobacter cloacae, strain 201 (MIC of imipenem and meropenem, 16 micrograms/ml). This strain was analyzed comparatively with the carbapenem-susceptible parent strain 200, an equally susceptible revertant, 201-Rev, and in vitro-selected mutants with different levels of carbapenem resistance. All strains produced similarly high amounts of the same cephalosporinase (pIapp = 8.8). Strain 201 apparently lacked two major outer membrane proteins of ca. 37 and 38 kDa, while 201-Rev produced only the 37-kDa protein. The permeability coefficient, determined with cephaloridine, was reduced up to ninefold in the resistant strains which also showed a substantial reduction in the uptake of [14C]meropenem. The introduction of the plasmid-borne ampD gene (whose product decreases the expression of ampC) resulted in almost complete cessation of cephalosporinase production in all strains and a substantial decrease in the MICs of the carbapenems which remained, however, 8- to 16-fold higher than those determined for the susceptible strains containing the ampD gene. This "residual" resistance was attributed to reduced outer membrane permeability. The contribution of cephalosporinase production was verified in a reverse experiment, in which the introduction of ampC into a low-level cephalosporinase producer resulted in a fourfold increase in the carbapenem MICs. From these results, we infer that reduced outer membrane permeability and high-level cephalosporinase production can operate in conjunction in clinical isolates of E. cloacae to confer imipenem resistance.

Bacterial Outer Membrane Proteins↗
PubMed1991

Imipenem- and meropenem-resistant mutants of Enterobacter cloacae and Proteus rettgeri lack porins.

Carbapenems such as imipenem and meropenem are not rapidly hydrolyzed by commonly occurring beta-lactamases. Nevertheless, it was possible, by mutagenesis and selection, to isolate mutant strains of Enterobacter cloacae and Proteus rettgeri that are highly resistant to meropenem and imipenem. Two alterations were noted in the E. cloacae mutants. First, the mutant strains appeared to be strongly derepressed in the production of beta-lactamases, which reached a very high level when the strains were grown in the presence of imipenem. Second, these mutants were deficient in the production of nonspecific porins, as judged by the pattern of outer membrane proteins as well as by reconstitution assays of permeability. As with most porin-deficient mutants, their cultures were unstable, and their cultivation in the absence of carbapenems rapidly led to an overgrowth of porin-producing revertants. Analysis of the data suggests that the synergism between the lowered outer membrane permeability and the slow but significant hydrolysis of carbapenems by the overproduced enzymes can explain the resistance phenotypes quantitatively, although the possibility of alteration of the target cannot be excluded at present. With P. rettgeri mutants, there was no indication of further derepression of beta-lactamase, but the enzyme hydrolyzed imipenem much more efficiently than the E. cloacae enzyme did. In addition, the major porin was absent in one mutant strain. These results suggest that a major factor for the carbapenem resistance of these enteric bacteria is the porin deficiency, and this conclusion forms a contrast to the situation in Pseudomonas aeruginosa, in which the most prevalent class of imipenem-resistant mutants appears to lack the specific channel protein D2 yet retains the major nonspecific porin F.

Bacterial Outer Membrane Proteins↗
PubMed1993

Sequences of wild-type and mutant ampD genes of Citrobacter freundii and Enterobacter cloacae.

The ampD gene product regulates the expression of AmpC beta-lactamase in gram-negative bacteria and is proposed to be involved in peptidoglycan metabolism. In this study, we sequenced the ampD wild type and three mutant genes of Enterobacter cloacae and Citrobacter freundii. They exhibited a high degree of homology with the corresponding gene of Escherichia coli except in the carboxy termini, where, in the wild-type genes of E. cloacae and C. freundii, four additional amino acids yielding the Ser-X-X-Lys motif were found. Evidence that this C-terminal region of the ampD gene product is necessary for activity was shown by constructing a deletion of the last 16 amino acids. The spontaneous mutation of ampD02 is an out-of-frame insertion and yields an inactive AmpD protein. The single-base-pair substitution of Gly for Asp-121 in ampD05 is responsible for a hyperinducible phenotype. These results demonstrate regions of the ampD gene and the corresponding protein which have functional importance for the induction of AmpC beta-lactamase in E. cloacae.

Amino Acid Sequence↗
PubMed1993

Biochemical properties of a carbapenem-hydrolyzing beta-lactamase from Enterobacter cloacae and cloning of the gene into Escherichia coli.

A clinical isolate of Enterobacter cloacae, strain NOR-1, exhibited resistance to imipenem and remained susceptible to extended-spectrum cephalosporins. Clavulanic acid partially restored the susceptibility of the strain to imipenem. Two beta-lactamases with isoelectric points (pI) of 6.9 and > 9.2 were detected in strain E. cloacae NOR-1; the higher pI corresponded to AmpC cephalosporinase. Plasmid DNA was not detected in E. cloacae NOR-1 and imipenem resistance could not be transferred into Escherichia coli JM109. The carbapenem-hydrolyzing beta-lactamase gene was cloned into plasmid pACYC184. One recombinant plasmid, pPTN1, harbored a 5.3-kb Sau3A fragment from E. cloacae NOR-1 expressing the carbapenem-hydrolyzing beta-lactamase. This enzyme (pI 6.9) hydrolyzed ampicillin, cephalothin, and imipenem more rapidly than it did meropenem and aztreonam, but it hydrolyzed extended-spectrum cephalosporins only weakly and did not hydrolyze cefoxitin. Hydrolytic activity was partially inhibited by clavulanic acid, sulbactam, and tazobactam, was nonsusceptible to chelating agents such as EDTA and 1,10-o-phenanthroline, and was independent of the presence of ZnCl2. Its relative molecular mass was 30,000 Da. Induction experiments concluded that the carbapenem-hydrolyzing beta-lactamase biosynthesis was inducible by cefoxitin and imipenem. Subcloning experiments with HindIII partial digests of pPTN1 resulted in a recombinant plasmid, designated pPTN2, which contained a 1.3-kb insert from pPTN1 and which conferred resistance to beta-lactam antibiotics. Hybridization studies performed with a 1.2-kb HindIII fragment from pPtN2 failed to determine any homology with ampC of E. cloacae, with other known beta-lactamase genes commonly found in members of the family Enterobacteriaceae (bla(TEM-1)) and bla(SHV-3) derivatives), and with previously described carbapenemase genes such as those from Xanthomonas maltophilia, Bacillus cereus, Bacteroides fragilis (cfiA), and Aeromonas hydrophila (cphA). This work describing the biochemical properties of a novel chromosome-encoded beta-lactamase from E. cloacae indicates that this enzyme differs from all the previously described carbapenemases. This is the first reported cloning of a carbapenem-hydrolyzing gene from a member of the family Enterobacteriaceae.

Carbapenems↗
PubMed1994

Extended-spectrum beta-lactamases in clinical isolates of Enterobacter gergoviae and Escherichia coli in China.

Resistance to ceftazidime, detected in isolates of Escherichia coli 5518 and Enterobacter gergoviae 3773 from our hospital, was transferred, together with resistance to aminoglycosides, trimethoprim, sulfonamide, and other beta-lactam antibiotics, by conjugation to E. coli JP559. Both E. coli transconjugants were resistant to ampicillin, all cephalosporins, and aztreonam but remained susceptible to cefoxitin and imipenem. The enzymes of the two transconjugant strains readily hydrolyzed cephalosporins in a spectrophotometric assay. Hybridization results suggested that the extended-spectrum beta-lactamase produced by E. coli 5518 was a non-TEM, non-SHV enzyme, the origin of which is currently unknown. The beta-lactamase produced by E. gergoviae 3773 was of the SHV type and was further proved to be SHV-2 by DNA sequencing. Thus, extended-spectrum beta-lactamases are occurring in China as well as in other parts of the world.

Cloning, Molecular↗
PubMed1995

Relative importances of outer membrane permeability and group 1 beta-lactamase as determinants of meropenem and imipenem activities against Enterobacter cloacae.

The roles of outer membrane permeability and Bush group 1 beta-lactamase activity in determining Enterobacter cloacae susceptibility to either meropenem or imipenem were investigated. A beta-lactamase-deficient strain was obtained by mutagenesis from a clinical isolate of E. cloacae, and a porin-deficient strain was selected from this mutant with cefoxitin. Both strains were transformed with the plasmid pAA20R, which contained the gene coding for the carbapenem-hydrolyzing CphA beta-lactamase, and the carbapenem permeability coefficients were measured by the Zimmermann and Rosselet technique (W. Zimmermann and A. Rosselet, Antimicrob. Agents Chemother. 12:368-372, 1977). The permeability coefficient of meropenem was roughly half that of imipenem in the normally permeable strain and almost seven times lower than that of imipenem in the porin-deficient strain. In the porin-deficient strain, the virtual absence of porins caused the MICs of meropenem to increase from 8 to 16 times, while it did not affect the MICs of imipenem. Conversely, the beta-lactamase affected imipenem but not meropenem activity: meropenem showed a similar activity in the parent strain and in the beta-lactamase-deficient mutant with both a low- and high-density inoculum, whereas imipenem was 16 times less active against the parent strain when the high-density inoculum was used. It is concluded that outer membrane permeability and stability to group 1 beta-lactamase have different impacts on the activities of meropenem and imipenem against E. cloacae.

Bacterial Proteins↗
PubMed1995

In vitro pharmacodynamics of piperacillin, piperacillin-tazobactam, and ciprofloxacin alone and in combination against Staphylococcus aureus, Klebsiella pneumoniae, Enterobacter cloacae, and Pseudomonas aeruginosa.

The time-kill curve methodology was used to determine the pharmacodynamics of piperacillin, ciprofloxacin, piperacillin-tazobactam and the combinations piperacillin-ciprofloxacin and ciprofloxacin-piperacillin-tazobactam. Kill curve studies were performed for piperacillin, ciprofloxacin, and piperacillin-tazobactam at concentrations of 0.25 to 50 times the MICs for 13 strains of bacteria: four Pseudomonas aeruginosa, three Enterobacter cloacae, three Klebsiella pneumoniae, and three Staphylococcus aureus isolates (tazobactam concentrations of 0.5, 4, and 12 micrograms/ml). By using a sigmoid Emax model and nonlinear least squares regression, the 50% lethal concentrations and the maximum lethal rates of each agent were determined for each bacterial strain. For piperacillin-ciprofloxacin and ciprofloxacin-piperacillin-tazobactam, kill curve studies were performed with concentrations obtained by the fractional maximal effect method (R. C. Li, J. J. Schentag, and D. E. Nix, Antimicrob. Agents Chemother. 37:523-531, 1993) and from individual 50% lethal concentrations and maximum lethal rates. Ciprofloxacin-piperacillin-tazobactam was evaluated only against the four P. aeruginosa strains. Interactions between piperacillin and ciprofloxacin were generally additive. At physiologically relevant concentrations of piperacillin and ciprofloxacin, ciprofloxacin had the highest rates of killing against K. pneumoniae. Piperacillin-tazobactam (12 micrograms/ml) had the highest rate of killing against E. cloacae. Piperacillin-ciprofloxacin with relatively higher ciprofloxacin concentrations had the greatest killing rates against S. aureus. This combination had significantly higher killing rates than piperacillin (P < 0.002). For all the bacterial strains tested, killing rates by ciprofloxacin were significantly higher than those by piperacillin-tazobactam (4 and 12 micrograms/ml had significantly higher killing rates than piperacillin alone (P < 0.02 and P < 0.004, respectively). The effect of the combination of piperacillin-ciprofloxacin, in which piperacillin concentrations were relatively higher, was not statistically different from that of piperacillin alone (p > or = 0.71). The combination of ciprofloxacin-piperacillin-tazobactam achieved greater killing than other combinations or monotherapies against P. aeruginosa. The reduction in the initial inoculum was 1 to 4 logs greater with ciprofloxacin-piperacillin-tazobactam at 4 and 12 micrograms/ml than with any other agent or combination of agents. On the basis of the additive effects prevalently demonstrated in the in vitro study, the combinations of piperacillin-ciprofloxacin and piperacillin-tazobactam are rational therapeutic options. Greater killing of P. aeruginosa was demonstrated with ciprofloxacin-piperacillin--tazobactam. Since treatment failure of P. aeruginosa pneumonia is a significant problem, clinical studies are warranted.

Anti-Infective Agents↗
PubMed1996

Differences in the resistant variants of Enterobacter cloacae selected by extended-spectrum cephalosporins.

The rates of development of resistance to ceftriaxone, ceftazidime, cefepime, and cefpirome in 10 strains of Enterobacter cloacae were determined by daily transfer for 7 days to fresh medium containing twofold serial dilutions of the antibiotics. Development of resistance to ceftriaxone was the most rapid; this was followed by ceftazidime, cefpirome, and cefepime. Resistant variants selected by ceftriaxone and ceftazidime were cross-resistant and produced very high levels of beta-lactamase. On the other hand, resistant variants selected by cefepime and cefpirome often had moderately high levels of beta-lactamase and diminished levels of the 39- to 40-kDa porin protein.

Bacterial Outer Membrane Proteins↗
PubMed1996

Sequencing and analysis of four new Enterobacter ampD Alleles.

Sequences of ampD genes from wild-type, temperature-sensitive, and stably derepressed mutants of the wild-type strain of Enterobacter cloacae 029 and the hyperinducible strain E. cloacae 1194E were determined and compared with the ampD gene of the wild-type strain E. cloacae 14. Seventy nucleotide differences were found between the wild-type sequences, resulting in 13 amino acid changes. The deduced amino acid changes do not correspond to published AmpC regulation mutations and expand the number of known mutations leading to altered AmpC beta-lactamase expression in members of the family Enterobacteriaceae.

Alleles↗