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PubMed1998

Contribution of beta-lactamases to beta-lactam susceptibilities of susceptible and multidrug-resistant Mycobacterium tuberculosis clinical isolates.

The beta-lactamases in 154 clinical Mycobacterium tuberculosis strains were studied. Susceptibilities to beta-lactam antibiotics, their combination with clavulanate (2:1), and two fluoroquinolones were determined in 24 M. tuberculosis strains susceptible to antimycobacterial drugs and in nine multiresistant strains. All 154 M. tuberculosis isolates showed a single chromosomal beta-lactamase pattern (pI 4.9 and 5.1). M. tuberculosis beta-lactamase hydrolyzes cefotaxime with a maximum rate of 22.5 +/- 2.19 IU/liter (strain 1382). Neither amoxicillin, carbenicillin, cefotaxime, ceftriaxone, nor aztreonam was active alone. Except for aztreonam, beta-lactam combinations with clavulanate produced better antimycobacterial activity.

Clavulanic Acid↗
PubMed1998

Ceftazidime-resistant Klebsiella pneumoniae and Escherichia coli isolates producing TEM-10 and TEM-43 beta-lactamases from St. Louis, Missouri.

Ceftazidime-resistant Escherichia coli and Klebsiella pneumoniae (49 and 102 isolates, respectively) were collected from Barnes-Jewish Hospital, St. Louis, Mo., from 1992 to 1996. They were uniformly resistant to ceftazidime, generally resistant to aztreonam, and variably susceptible to cefotaxime. Four representative E. coli strains and 15 Klebsiella strains were examined. From one to four beta-lactamases were produced per strain, with three possible enzymes related to ceftazidime resistance: enzymes with pI values of 5.6, 6.1, or 7.6. By pulsed-field gel electrophoresis there were at least 13 different Klebsiella strain types and 3 different E. coli strain types, indicating that the outbreak was not clonal. After cloning and sequencing of the beta-lactamase-encoding genes, the enzyme with a pI of 5.6 was identified as TEM-10. The enzyme with a pI of 6.1 was a novel TEM variant (TEM-43) with Lys at 104, His at 164, and Thr at 182. TEM-43 showed broad-spectrum hydrolytic activity against all penicillins, with the highest hydrolysis rate for ceftazidime compared to those for the other expanded-spectrum cephalosporins. Aztreonam was also a good substrate for TEM-43, with hydrolytic activity similar to that of ceftazidime and affinity higher than that of ceftazidime. The TEM-43 beta-lactamase was well inhibited by clavulanic acid and tazobactam at concentrations of < 10 nM. Sulbactam was less effective than the other inhibitors. The Thr182 mutation previously reported in an inhibitor-resistant beta-lactamase did not cause the TEM-43 enzyme to become resistant to any of the inhibitors.

Ceftazidime↗
PubMed1998

CTX-M-5, a novel cefotaxime-hydrolyzing beta-lactamase from an outbreak of Salmonella typhimurium in Latvia.

At a children's hospital in Riga, Latvia, isolates identified as Salmonella typhimurium were found to be resistant to expanded-spectrum cephalosporins. Two of the resistant strains were analyzed for the mechanism of cephalosporin resistance. Isoelectric focusing revealed a common beta-lactamase with a pI of 8.8. In addition, one of the strains produced a pI 7.6 beta-lactamase. A transconjugant producing only the pI 7.6 enzyme was susceptible to expanded-spectrum cephalosporins; therefore, this enzyme was most likely SHV-1. Transformants producing only the pI 8.8 beta-lactamase were resistant to cefotaxime and aztreonam but were susceptible or intermediate to ceftazidime. A substrate profile determined spectrophotometrically with purified enzyme revealed potent activity against cefotaxime, with a relative kcat value of 95 (benzylpenicillin equal to 100). The enzyme showed lower relative kcat values for ceftazidime (3.3) and aztreonam (9.3). In addition, the enzyme was inhibited by clavulanate, sulbactam and tazobactam, with 50% inhibitory concentrations of 19, 100, and 3.4 nM, respectively. These results indicated the presence of an unusual extended-spectrum beta-lactamase. The gene expressing the pI 8.8 beta-lactamase was cloned. Nucleotide sequencing revealed a beta-lactamase gene that differs from the gene encoding CTX-M-2, which also originated from S. typhimurium, by 11 nucleotides, 4 of which result in amino acid substitutions: Ala27Thr, Val230Gly, Glu254Ala, and Ile278Val. These results indicated the presence of a novel extended-spectrum beta-lactamase, designated CTX-M-5, that specifically confers resistance to cefotaxime.

Amino Acid Sequence↗
PubMed1999

Competition of various beta-lactam antibiotics for the major penicillin-binding proteins of Helicobacter pylori: antibacterial activity and effects on bacterial morphology.

The penicillin-binding proteins (PBPs) of helical (log-phase) Helicobacter pylori ATCC 43579 were identified by using biotinylated ampicillin. The major PBPs had apparent molecular masses of 47, 60, 63, and 66 kDa; an additional minor PBP of 95 to 100 kDa was also detected. The relative affinities of various beta-lactams for these PBPs were tested by competitive-binding assays. Only PBP63 appeared to be significantly bound to each of the competing antibiotics, whereas PBP66 strongly bound mezlocillin, oxacillin, amoxicillin, and ceftriaxone. Whereas most of the beta-lactams significantly bound two or more PBPs, aztreonam specifically targeted PBP63. The influence of sub-MICs of these beta-lactams on the morphologies of log-phase H. pylori was observed at both the phase-contrast and transmission electron microscopy levels. Each of the eight beta-lactams examined induced blebbing and sphere formation, whereas aztreonam was the only antibiotic studied which induced pronounced filamentation in H. pylori. Finally, studies comparing the PBPs of helical (log-phase) cultures with those of coccoid (7-, 14-, and 21-day-old) cultures of H. pylori revealed that the major PBPs at 60 and 63 kDa seen in the helical form were almost undetectable in the coccoid forms, whereas PBP66 remained the major PBP in the coccoid forms, although somewhat reduced in level compared to the helical form. PBP47 was present in both forms at approximately equal concentrations. These studies thus identified the major PBPs in both helical and coccoid forms of H. pylori and compared the relative affinities of seven different beta-lactams for the PBPs in the helical forms and their effects on bacterial morphology.

Ampicillin↗
PubMed2000

A novel class A extended-spectrum beta-lactamase (BES-1) in Serratia marcescens isolated in Brazil.

Serratia marcescens Rio-5, one of 18 extended-spectrum beta-lactamase (ESBL)-producing strains isolated in several hospitals in Rio de Janeiro (Brazil) in 1996 and 1997, exhibited a high level of resistance to aztreonam (MIC, 512 microgram/ml) and a distinctly higher level of resistance to cefotaxime (MIC, 64 microgram/ml) than to ceftazidime (MIC, 8 microgram/ml). The strain produced a plasmid-encoded ESBL with a pI of 7.5 whose bla gene was not related to those of other plasmid-mediated Ambler class A ESBLs. Cloning and sequencing revealed a bla gene encoding a novel class A beta-lactamase in functional group 2be, designated BES-1 (Brazil extended-spectrum beta-lactamase). This enzyme had 51% identity with chromosomal class A penicillinase of Yersinia enterocolitica Y56, which was the most closely related enzyme and 47 to 48% identity with CTX-M-type beta-lactamases, which were the most closely related ESBLs. In common with CTX-M enzymes, BES-1 exhibited high cefotaxime-hydrolyzing activity (k(cat), 425 s(-1)). However, BES-1 differed from CTX-M enzymes by its significant ceftazidime-hydrolyzing activity (k(cat), 25 s(-1)), high affinity for aztreonam (K(i), 1 microM), and lower susceptibility to tazobactam (50% inhibitory concentration [IC(50)], 0.820 microM) than to clavulanate (IC(50), 0.045 microM). Likewise, certain characteristic structural features of CTX-M enzymes, such as Phe-160, Ser-237, and Arg-276, were observed for BES-1, which, in addition, harbored different residues (Ala-104, Ser-171, Arg-220, Gly-240) and six additional residues at the end of the sequence. BES-1, therefore, may be an interesting model for further investigations of the structure-function relationships of class A ESBLs.

Amino Acid Sequence↗
PubMed2000

TLA-1: a new plasmid-mediated extended-spectrum beta-lactamase from Escherichia coli.

Escherichia coli R170, isolated from the urine of an infected patient, was resistant to expanded-spectrum cephalosporins, aztreonam, ciprofloxacin, and ofloxacin but was susceptible to amikacin, cefotetan, and imipenem. This particular strain contained three different plasmids that encoded two beta-lactamases with pIs of 7.0 and 9.0. Resistance to cefotaxime, ceftazidime, aztreonam, trimethoprim, and sulfamethoxazole was transferred by conjugation from E. coli R170 to E. coli J53-2. The transferred plasmid, RZA92, which encoded a single beta-lactamase, was 150 kb in length. The cefotaxime resistance gene that encodes the TLA-1 beta-lactamase (pI 9.0) was cloned from the transconjugant by transformation to E. coli DH5alpha. Sequencing of the bla(TLA-1) gene revealed an open reading frame of 906 bp, which corresponded to 301 amino acid residues, including motifs common to class A beta-lactamases: (70)SXXK, (130)SDN, and (234)KTG. The amino acid sequence of TLA-1 shared 50% identity with the CME-1 chromosomal class A beta-lactamase from Chryseobacterium (Flavobacterium) meningosepticum; 48.8% identity with the VEB-1 class A beta-lactamase from E. coli; 40 to 42% identity with CblA of Bacteroides uniformis, PER-1 of Pseudomonas aeruginosa, and PER-2 of Salmonella typhimurium; and 39% identity with CepA of Bacteroides fragilis. The partially purified TLA-1 beta-lactamase had a molecular mass of 31.4 kDa and a pI of 9.0 and preferentially hydrolyzed cephaloridine, cefotaxime, cephalothin, benzylpenicillin, and ceftazidime. The enzyme was markedly inhibited by sulbactam, tazobactam, and clavulanic acid. TLA-1 is a new extended-spectrum beta-lactamase of Ambler class A.

Amino Acid Sequence↗
PubMed2001

Novel carbapenem-hydrolyzing beta-lactamase, KPC-1, from a carbapenem-resistant strain of Klebsiella pneumoniae.

A Klebsiella pneumoniae isolate showing moderate to high-level imipenem and meropenem resistance was investigated. The MICs of both drugs were 16 microg/ml. The beta-lactamase activity against imipenem and meropenem was inhibited in the presence of clavulanic acid. The strain was also resistant to extended-spectrum cephalosporins and aztreonam. Isoelectric focusing studies demonstrated three beta-lactamases, with pIs of 7.2 (SHV-29), 6.7 (KPC-1), and 5.4 (TEM-1). The presence of bla(SHV) and bla(TEM) genes was confirmed by specific PCRs and DNA sequence analysis. Transformation and conjugation studies with Escherichia coli showed that the beta-lactamase with a pI of 6.7, KPC-1 (K. pneumoniae carbapenemase-1), was encoded on an approximately 50-kb nonconjugative plasmid. The gene, bla(KPC-1), was cloned in E. coli and shown to confer resistance to imipenem, meropenem, extended-spectrum cephalosporins, and aztreonam. The amino acid sequence of the novel carbapenem-hydrolyzing beta-lactamase, KPC-1, showed 45% identity to the pI 9.7 carbapenem-hydrolyzing beta-lactamase, Sme-1, from Serratia marcescens S6. Hydrolysis studies showed that purified KPC-1 hydrolyzed not only carbapenems but also penicillins, cephalosporins, and monobactams. KPC-1 had the highest affinity for meropenem. The kinetic studies also revealed that clavulanic acid and tazobactam inhibited KPC-1. An examination of the outer membrane proteins of the parent K. pneumoniae strain demonstrated that the strain does not express detectable levels of OmpK35 and OmpK37, although OmpK36 is present. We concluded that carbapenem resistance in K. pneumoniae strain 1534 is mainly due to production of a novel Bush group 2f, class A, carbapenem-hydrolyzing beta-lactamase, KPC-1, although alterations in porin expression may also play a role.

Amino Acid Sequence↗
PubMed2002

Mechanisms of decreased susceptibility to cefpodoxime in Escherichia coli.

Cefpodoxime is one of five antimicrobial agents recommended by the National Committee for Clinical Laboratory Standards for screening isolates of Klebsiella spp. and Escherichia coli for extended-spectrum beta-lactamase (ESBL) production. In a prior study, we noted that among 131 E. coli isolates for which the MIC of at least one extended-spectrum cephalosporin (ESC) or aztreonam was > or =2 micro g/ml (suggesting the presence of ESBL production), there were 59 isolates (45.0%) for which the MIC of cefpodoxime was 2 to 4 micro g/ml (i.e., a positive ESBL screening test), but the MICs of ceftazidime, cefotaxime, and ceftriaxone were < or =1 micro g/ml (below the ESBL screening breakpoint). Thus, the results appeared to be false-positive ESBL screening tests. These 59 isolates were divided into five phenotypic groups based on the susceptibility patterns of the organisms to a variety of beta-lactam agents and further characterized. The first group (32 isolates) all produced a TEM-1 beta-lactamase, and changes in the major outer membrane proteins were detected in representative strains. The second group (18 isolates) lacked bla(TEM) but showed a number of porin changes; some also showed a modest elevation in production of the AmpC chromosomal beta-lactamase. In the third phenotypic group (seven isolates) all expressed an OXA-30 beta-lactamase. Some also harbored altered porins. The two remaining phenotypes each had a distinct pattern of porin changes with or without beta-lactamase production. These data indicate that several factors are associated with decreased susceptibility to cefpodoxime in E. coli, but none of the mechanisms are related to ESBL production. Current screening methods produced false-positive ESBL results for these isolates. Such isolates should not be classified as containing ESBLs, nor should interpretations of ESCs or aztreonam susceptibility be changed to resistant on test reports for these isolates.

Ceftizoxime↗
PubMed2002

Comparative stability studies of antipseudomonal beta-lactams for potential administration through portable elastomeric pumps (home therapy for cystic fibrosis patients) and motor-operated syringes (intensive care units).

The stability of antipseudomonal beta-lactams in concentrated solutions was examined in view of their potential administration by continuous infusion with external pumps (for intensive care patients) or with portable pumps carried under clothing (for cystic fibrosis patients). Aztreonam (100 g/liter), piperacillin (128 g/liter, with tazobactam), and azlocillin (128 g/liter) remained 90% stable for up to more than 24 h at 37 degrees C (mezlocillin [128 g/liter] was stable at 25 degrees C but not at 37 degrees C). Ceftazidime (120 g/liter), cefpirome (32 g/liter), and cefepime (50 g/liter) remained 90% stable for up to 24, 23.7, and 20.5 h at 25 degrees C but only for 8, 7.25, and 13 h at 37 degrees C, respectively. The control of temperature therefore appears to be critical for all three cephalosporins that cannot be recommended for use in portable pumps carried under clothes for prolonged periods for reasons of stability. Cefpirome and cefepime solutions developed an important color change (from light yellow to dark red) upon exposure when stored at 30 degrees C or higher. Degradation of ceftazidime was accompanied by the liberation of pyridine which, at 37 degrees C, was in excess of what is allowed by the U.S. Pharmacopeia, i.e., 1.1 mg/liter, after 8 and 12 h for drug concentrations of 12 and 8.3%, respectively. Imipenem and meropenem are too unstable (10% degradation at 25 degrees C after 3.5 and 5.15 h, respectively) to be recommended for use by continuous infusion. Faropenem, examined in comparison with imipenem and meropenem, proved as stable as aztreonam or piperacillin.

Anti-Bacterial Agents↗
PubMed2005

OXA-46, a new class D beta-lactamase of narrow substrate specificity encoded by a blaVIM-1-containing integron from a Pseudomonas aeruginosa clinical isolate.

A novel OXA-type enzyme, named OXA-46, was found to be encoded by a gene cassette inserted into a class 1 integron from a multidrug-resistant Pseudomonas aeruginosa clinical isolate. The variable region of the integron also contained a bla(VIM-1) metallo-beta-lactamase cassette and a duplicated aacA4 aminoglycoside acetyltransferase cassette. OXA-46 belongs to the OXA-2 lineage of class D beta-lactamases. It exhibits 78% sequence identity with OXA-2 and the highest similarity (around 92% identity) with another OXA-type enzyme detected in clinical isolates of Burkholderia cepacia and in unidentified bacteria from a wastewater plant. Expression of bla(OXA-46) in Escherichia coli decreased susceptibility to penicillins and narrow-spectrum cephalosporins but not to extended-spectrum cephalosporins, cefsulodin, aztreonam, or carbapenems. The enzyme was overproduced in E. coli and purified by two anion-exchange chromatography steps (approximate yield, 6 mg/liter). OXA-46 was made of a 28.5-kDa polypeptide and exhibited an alkaline pI (7.8). In its native form OXA-46 appeared to be dimeric, and the oligomerization state was not affected by EDTA. Kinetic analysis of OXA-46 revealed a specificity for narrow-spectrum substrates, including oxacillin, other penicillins (but not temocillin), and narrow-spectrum cephalosporins. The enzyme apparently did not interact with temocillin, oxyimino-cephalosporins, or aztreonam. OXA-46 was inactivated by tazobactam and carbapenems and, although less efficiently, also by clavulanic acid. Enzyme activity was not affected either by EDTA or by divalent cations and exhibited low susceptibility to NaCl. These findings underscore the functional and structural diversity that can be encountered among class D beta-lactamases.

Amino Acid Sequence↗
PubMed1993

Tumor necrosis factor alpha (TNF-alpha) production in mice immunized with Escherichia coli: correlation with mortality after lethal challenge and production of a native inhibitor of TNF-alpha activity.

The kinetics of tumor necrosis factor alpha (TNF-alpha) production, the correlation between cytokine levels and mortality rates after lethal challenge, and the production of a native inhibitor of TNF-alpha activity was investigated in mice immunized with formalin-killed Escherichia coli. Groups of mice were injected for 8 weeks with either untreated bacteria or bacteria treated with 0.5 MIC of aztreonam and subsequently challenged with 100 50% lethal doses of viable E. coli. Mice receiving saline only (controls) died within 24 h. The mortality of mice immunized with aztreonam-treated E. coli was significantly lower than that of mice immunized with untreated E. coli. There were no measurable levels of TNF-alpha in sera obtained from control mice during the entire period of immunization. TNF-alpha levels ranging from 90 to 306 U/ml were measured 90 min after each vaccination in sera obtained from mice immunized with untreated E. coli. Sera from mice immunized with antibiotic-treated E. coli showed lower TNF-alpha levels, ranging from 40 to 128 U/ml. TNF-alpha levels measured 90 min after lethal challenge correlated with the mortality rate observed in each group (r = 0.95). The cytotoxic activity of recombinant murine TNF-alpha was inhibited by the sera from immunized mice but not by the sera from controls. The inhibition was drastically reduced by preincubation of the sera with staphylococcal protein A. In immunoblot experiments, class G immunoglobulins reacting with recombinant murine TNF-alpha were observed in the sera of immunized mice. These data confirm the correlation existing between TNF-alpha levels and mortality and suggest that native inhibitors may play a role in the regulation of the biological function of the cytokine.

Animals↗
PubMed2003

Probing the catalytic activity of a cell division-specific transpeptidase in vivo with beta-lactams.

Penicillin-binding protein 3 (PBP3; also called FtsI) is a transpeptidase that catalyzes cross-linking of the peptidoglycan cell wall in the division septum of Escherichia coli. To determine whether the catalytic activity of PBP3 is activated during division, we assayed acylation of PBP3 with three beta-lactams (cephalexin, aztreonam, and piperacillin) in growing cells. Acylation of PBP3 with cephalexin, but not aztreonam or piperacillin, appeared to be stimulated by cell division. Specifically, cephalexin acylated PBP3 about 50% faster in a population of dividing cells than in a population of filamentous cells in which division was inhibited by inactivation or depletion of FtsZ, FtsA, FtsQ, FtsW, or FtsN. However, in a simpler in vitro system using isolated membranes, acylation with cephalexin was not impaired by depletion of FtsW or FtsN. A conflicting previous report that the ftsA3(Ts) allele interferes with acylation of PBP3 was found to be due to the presence of a thermolabile PBP3 in the strain used in that study. The new findings presented here are discussed in light of the hypothesis that the catalytic activity of PBP3 is stimulated by interaction(s) with other division proteins. We suggest that there might be allosteric activation of substrate binding.

Bacterial Proteins↗
PubMed1986

Effect of storage temperature and pH on the stability of antimicrobial agents in MIC trays.

Twelve antimicrobial agents, ampicillin, aztreonam, cefamandole, cefazolin, cefonicid, ceforanide, ceftazidime, ceftizoxime, ceftriaxone, cefuroxime, ciprofloxacin, and norfloxacin, were prepared at pH 6.80 and 7.31 in microdilution trays for storage at 4, -10, -25, and -70 degrees C and for weekly susceptibility testing. All 12 drugs had stable biological activity when stored at -70 degrees C for 1 year. All but ampicillin and aztreonam were stable at -25 degrees C. Storage at -10 degrees C was least satisfactory. Desiccation occurred at 4 degrees C, but short-term storage at this temperature is possible since the antimicrobial agents are stable for up to several months.

Anti-Bacterial Agents↗
PubMed1992

Comparison of the E test and microdilution for detection of beta-lactam-resistant mutants that are stably derepressed for type I beta-lactamase.

The activities of cefotaxime, ceftazidime, piperacillin, and aztreonam were compared in the E test and broth microdilution test against 30 gram-negative bacterial mutants derepressed for type I beta-lactamases. The results demonstrated complete agreement between 24-h MICs of 80 to 83% and essential agreement between 24-h MICs of 90 to 97%. When sufficient growth was present for the E test to be read at 6 h, the essential agreement between 6- and 24-h E-test MICs was 100% for ceftazidime, piperacillin, and aztreonam and 85% for cefotaxime.

Anti-Bacterial Agents↗
PubMed2004

Multifocal detection of multidrug-resistant Pseudomonas aeruginosa producing the PER-1 extended-spectrum beta-lactamase in Northern Italy.

Forty-four nonreplicate clinical isolates of Pseudomonas aeruginosa that were resistant to extended-spectrum cephalosporins (ceftazidime and cefepime) and aztreonam, that putatively produced an acquired extended- spectrum beta-lactamase (ESBL), according to the results of a double-disk synergy test, and that had been involved in nosocomial outbreaks were obtained from six different hospitals in northern Italy and screened for the presence of bla(PER) ESBL determinants. Twenty isolates, associated with nine independent outbreaks that occurred in five hospitals in the Milan area and its surroundings during 1995-2000, were found to carry an acquired bla(PER-1) gene. PER-1 producers representative of the nine outbreaks exhibited a multidrug resistance (MDR) phenotype, including resistance to extended-spectrum cephalosporins, aztreonam, meropenem, aminoglycosides, and in most cases, imipenem and ciprofloxacin. An analysis of macrorestriction profiles of their genomic DNAs by pulsed-field gel electrophoresis revealed an overall clonal diversity of the PER-1 producers, although interhospital clonal spread was also observed. The bla(PER-1) gene was not transferable and appeared to be chromosomally located. An analysis of the EcoRI and EcoRV restriction fragment length polymorphisms of the bla(PER-1) locus revealed identical patterns for all isolates, and the characterization of a 1.9-kb region containing bla(PER-1) revealed a conserved structure in representatives of the various clonal lineages. The present findings indicate that MDR P. aeruginosa clones producing the PER-1 ESBL are endemic to this area of northern Italy, where they have been circulating since the mid-1990s and have been associated with several nosocomial outbreaks.

Amino Acid Sequence↗
PubMed2004

Nosocomial transmission of CTX-M-2 beta-lactamase-producing Acinetobacter baumannii in a neurosurgery ward.

Three strains of cefotaxime (CTX)-resistant Acinetobacter baumannii, FM0209680, FM0300106, and FM0301433, were isolated from transtracheal aspirate cultures of three patients with probable nosocomial infections in a neurosurgery ward in Japan. The CTX MICs for these isolates were greater than 128 microg/ml but were drastically reduced in the presence of 4 microg of clavulanic acid per ml. These strains were also resistant to ceftriaxone, cefpodoxime, and aztreonam but were susceptible to ceftazidime and imipenem. The profile of resistance to various broad-spectrum beta-lactams was transferred by conjugation. Strain FM0209680 was not eradicated from case patient 1 by administration of imipenem, ceftazidime, and levofloxacin, even after a 6-month hospitalization period. Strains FM0300106 and FM0301433 were isolated from case patients 2 and 3 during the sixth week following admission, respectively, and then each patient was colonized for 3 weeks. Eradication of FM0300106 was successfully obtained from case patient 2 by imipenem treatment, while administration of imipenem was continued to prevent pneumonia. Prophylactic antimicrobial therapy was discontinued in case patient 3 because of the lack of pneumonic symptoms, and FM0301433 disappeared after the discontinuation of antimicrobial chemotherapy. All three strains carried the bla(CTX-M-2) gene, and the appearance of colonies in the growth-inhibitory zones around disks of CTX and aztreonam in double-disk synergy tests suggested inducible beta-lactamase production in these A. baumannii strains. The ribotyping investigation suggested that all these strains belong to the same clonal lineage. The plasmids harbored by A. baumannii had the same restriction profile as those harbored by Proteus mirabilis strains previously isolated in a urology ward of the Funabashi Medical Center.

Acinetobacter Infections↗
PubMedDate not supplied

Patch tests for diagnosis of delayed hypersensitivity to cephalosporins.

BACKGROUND: Few studies have reported delayed hypersensitivity reactions to systemically administered cephalosporins. The diagnostic procedures and extracts for these reactions are not standardized, and little is known about the extent of cross reactivity among different cephalosporins. CASES REPORT: We report 2 cases of delayed hypersensitivity reactions due to cephalosporins presenting as erythrodermia. Case 1. An 80-year-old man developed generalized pruritus and erythema 2-3 days after starting treatment with cefuroxime. The drug was stopped and antihistamines and corticosteroids were administered. The patient improved 5-6 days later, and mild superficial desquamation was observed. Case 2. A 66-year-old woman experienced similar symptoms 4-5 days after beginning cefazolin. She reported a similar reaction with ceftazidime 8 years previously. METHODS AND RESULTS: Skin prick tests and specific IgE against penicillin G and V, amoxicillin, ampicillin and cephalosporins were negative. Intradermal tests with ceftazidime and cefazolin were positive in case 2 at delayed reading. Patch tests using benzylpenicillin, ampicillin, amoxicillin, several cephalosporins, aztreonam and imipenem were positive to all the cephalosporins tested (at 48 and 96 hours) and were negative to the other betalactams. Controlled administration of amoxicillin, benzylpenicillin, aztreonam and imipenem was well tolerated by both patients. CONCLUSIONS: 1) We report 2 cases of delayed hypersensitivity reactions due to cephalosporins presenting as erythrodermia. 2) Epicutaneous tests were useful for diagnosis. 3) Both patients tested positive to all cephalosporins and negative to other betalactams.

Aged↗
PubMedDate not supplied

Susceptibility surveillance among gram-negative bacilli at a cancer center.

We conducted a survey of susceptibility among 758 gram-negative bacilli (GNB; collected from cancer patients over a 3-month period) to commonly used antibiotics. The overall resistance among GNB was least for piperacillin/tazobactam and meropenem (5 and 6%, respectively) followed by cefepime (8%), imipenem (9%), amikacin (12%), ofloxacin (13%), ciprofloxacin, ceftazidime and ticarcillin/clavulanate (14% each), aztreonam (18%) and tobramycin (24%). In comparison to data on antibiotic resistance to ceftazidime, imipenem, ciprofloxacin and aztreonam in similar studies in 1985 and 1994, resistance has significantly increased to all four antibiotic classes. Based on our current study, meropenem, cefepime, imipenem and piperacillin/tazobactam would be the most appropriate choices in our institution for empiric therapy of GNB infections in febrile neutropenic patients.

Anti-Bacterial Agents↗