Ureidopenicillins Are Potent Inhibitors of Penicillin-Binding Protein 2 from Multidrug-Resistant Neisseria gonorrhoeae H041.

Effective treatment of gonorrhea is threatened by the increasing prevalence of Neisseria gonorrhoeae strains resistant to the extended-spectrum cephalosporins (ESCs). Recently, we demonstrated the promise of the third-generation cephalosporin cefoperazone as an antigonococcal agent due to its rapid second-order rate of acylation against penicillin-binding protein 2 (PBP2) from the ESC-resistant strain H041 and robust antimicrobial activity against H041. Noting the presence of a ureido moiety in cefoperazone, we evaluated a subset of structurally similar ureido ß-lactams, including piperacillin, azlocillin, and mezlocillin, for activity against PBP2 from H041 using biochemical and structural analyses. We found that the ureidopenicillin piperacillin has a second-order rate of acylation against PBP2 that is 12-fold higher than cefoperazone and 85-fold higher than ceftriaxone and a lower MIC against H041 than ceftriaxone. Surprisingly, the affinity of ureidopenicillins for PBP2 is minimal, indicating that their inhibitory potency is due to a higher rate of the acylation step of the reaction compared to cephalosporins. Enhanced acylation results from the combination of a penam scaffold with a 2,3-dioxopiperazine-containing R1 group. Crystal structures show that the ureido ß-lactams overcome the effects of resistance mutations present in PBP2 from H041 by eliciting conformational changes that are hindered when PBP2 interacts with the weaker inhibitor ceftriaxone. Overall, our results support the potential of piperacillin as a treatment for gonorrhea and provide a framework for the future design of ß-lactams with improved activity against ESC-resistant N. gonorrhoeae.

Short-term use of ceftriaxone sodium leads to intestinal barrier disruption and ultrastructural changes of kidney in SD rats.

OBJECTIVE: Antibiotic treatments are known to disturb gut microbiota, but their effects on the mucosal barrier and extraintestinal diseases are rarely discussed. The aim of this study was to evaluate and visualize the impact of antibiotics on colonic mucus and the microbial community, and to assess whether intestinal dysbacteriosis is involved in the pathogenesis and progression of extraintestinal diseases in vivo. MATERIALS AND METHODS: Twenty-one SD rats were randomly assigned into three groups followed by different experimental treatments. The albumin-creatinine ratio, urinary protein and occult blood semi-quantified test were tested. Fecal samples were collected at different time points (0,4, and 12 weeks) for 16S rRNA gene sequencing. Colon and kidney specimens were examined using light microscopy and transmission electron microscopy (TEM) to identify morphological changes. RESULTS: Ceftriaxone intervention for one week did not cause any symptoms of diarrhea or weight loss, but the alpha and beta diversities of gut microbiota decreased quickly and significantly, a lower Firmicutes/Bacteroidetes (F/B) ratio was observed. At week 12, although the alpha and beta diversities increased to a level similar to that of the control (CON) group, LEfSe analysis indicated that the microbial community composition still differed significantly in each group. In addition, KEGG metabolic prediction revealed different metabolic functions in each group. TEM examination of colon revealed that dramatic morphological changes were observed in the ceftriaxone (Cef) group, wherein microvilli were misaligned and shortened significantly and morphologically intact bacteria were seen on the epithelial cell surface. TEM examination of kidneys from the Cef group showed characteristic glomerular changes in the form of widely irregularly thickened glomerular basement membrane (GBM) and foot process fusion or effacement; mild thickening of the GBM and foot process fusion was detected when ceftriaxone and Resatorvid (TAK242, an inhibitor of TLR4 signaling) are used together in the ceftriaxone + TAK242 (TAK) group. CONCLUSIONS: Short-term use of ceftriaxone induced dynamic changes of gut microbiota and lead to intestinal barrier disruption and ultrastructural changes of kidneys in the SD rats. Moreover, interference with the TLR4-dependent signaling pathway can alleviate the damage to the intestinal barrier and kidney.

Restoring calcium homeostasis in Purkinje cells arrests neurodegeneration and neuroinflammation in the ARSACS mouse model.

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is caused by mutations in SACS gene encoding sacsin, a huge protein highly expressed in cerebellar Purkinje cells (PCs). Patients with ARSACS, as well as mouse models, display early degeneration of PCs, but the underlying mechanisms remain unexplored, with no available treatments. In this work, we demonstrated aberrant calcium (Ca2+) homeostasis and its impact on PC degeneration in ARSACS. Mechanistically, we found pathological elevation in Ca2+-evoked responses in Sacs-/- PCs as the result of defective mitochondria and ER trafficking to distal dendrites and strong downregulation of key Ca2+ buffer proteins. Alteration of cytoskeletal linkers, which we identified as specific sacsin interactors, likely account for faulty organellar trafficking in Sacs-/- cerebellum. Based on this pathogenetic cascade, we treated Sacs-/- mice with Ceftriaxone, a repurposed drug that exerts neuroprotection by limiting neuronal glutamatergic stimulation and, thus, Ca2+ fluxes into PCs. Ceftriaxone treatment significantly improved motor performances of Sacs-/- mice, at both pre- and postsymptomatic stages. We correlated this effect to restored Ca2+ homeostasis, which arrests PC degeneration and attenuates secondary neuroinflammation. These findings disclose key steps in ARSACS pathogenesis and support further optimization of Ceftriaxone in preclinical and clinical settings for the treatment of patients with ARSACS.

Prevalence of Efflux Pump and Porin-Related Antimicrobial Resistance in Clinical Klebsiella pneumoniae in Baghdad, Iraq.

Klebsiella pneumoniae is an opportunistic bacterium that causes many infections, including septicemia, pneumonia, urinary tract infection, and liver abscesses. There are many mechanisms for antibiotic resistance and K. pneumonia is considered a multidrug-resistant pathogen. This study aimed to find the correlation between the susceptibility of K. pneumonia to certain antibiotics with the porin-related resistance and pumps mechanisms. In total, two genes that are responsible for porin formation were considered in the current study OmpK-35gene and OmpK-36 gene, in addition to other four genes (CfiaS, CfiaL, MFS, and MdtK genes) related to an efflux pump mechanism of antibiotic resistance. The bacterial resistance was investigated towards five cephalosporins (Cefazolin, Cefoxitin, Ceftazidime, Ceftriaxone, and Cefepime) and two carbapenems (imipenem and ertapenem). Clinical samples, including blood, swabs, and urine, consisting of 20 specimens for each group, were collected from patients who attended three hospitals in Baghdad. The VITEK-2 system and genetic tests (polymerase chain reaction and sequencing) of bacterial isolates were applied to confirm the diagnosis of K. pneumoniae and detect the antibiotic sensitivity profile. The results showed that 51 (85%) and 15 (25%) of the total 60 isolates had positive results for OmpK-35 and Omp-K36 genes, respectively. The MFS and MdtK genes were observed (70-88.3%) in cephalosporin-resistant isolates of K. pneumoniae. There were no significant variations of bacterial resistance genes of antibiotics within the specimen groups. It was concluded that the bacterial resistance of the selected antibiotics was elevated markedly with the loss of the OmpK-36 gene with a high expression of MFS and MdtK genes and a slight minimal occurrence in the new generation of carbapenems. The best antimicrobial agent was ertapenem with a percentage of 0% of resistance in all bacterial isolates.

Role of suppressing GLT-1 and xCT in ceftriaxone-induced attenuation of relapse-like alcohol drinking in alcohol-preferring rats.

Alcohol dependence results in long-lasting neuroadaptive changes in meso-corticolimbic system, especially in the nucleus accumbens (NAc), which drives relapse-like ethanol drinking upon abstinence or withdrawal. Within NAc, altered glutamate homeostasis is one of the neuroadaptive changes caused by alcohol dependence. Accumbal glutamate homeostasis is tightly maintained through glutamate transporter 1 (GLT-1) and cystine-glutamate antiporter (xCT). But the role of GLT-1 and xCT in relapse-like ethanol drinking is poorly understood. Here, we used alcohol-preferring (P) rats in relapse-like ethanol drinking paradigm to (a) determine the effect of relapse-like ethanol drinking on gene and protein expression of GLT-1 and xCT in NAc, measured by quantitative polymerase chain reaction (qPCR) and Western blot, respectively; (b) examine if glutamate uptake is affected by relapse-like ethanol drinking in NAc, measured by radioactive glutamate uptake assay; (c) elucidate if upregulation of either/both GLT-1 or/and xCT through ceftriaxone is/are required to attenuate relapse-like ethanol drinking. The GLT-1 or xCT protein expression was suppressed during ceftriaxone treatments through microinjection of GLT-1/xCT anti-sense vivo-morpholinos. We found that relapse-like ethanol drinking did not affect the gene and protein expression of GLT-1 and xCT in NAc. The glutamate uptake was also unaltered. Ceftriaxone (200 mg/kg body weight, i.p.) treatments during the last 5 days of abstinence attenuated relapse-like ethanol drinking. The suppression of GLT-1 or xCT expression prevented the ceftriaxone-induced attenuation of relapse-like ethanol drinking. These findings confirm that upregulation of both GLT-1 and xCT within NAc is crucial for ceftriaxone-mediated attenuation of relapse-like ethanol drinking.

Multidrug-resistant Neisseria gonorrhoeae infection in heterosexual men with reduced susceptibility to ceftriaxone, first report in Thailand.

The global rapid emergence of azithromycin/ceftriaxone resistant Neisseria gonorrhoeae threatens current recommend azithromycin/ceftriaxone dual therapy for gonorrhea to ensure effective treatment. Here, we identified the first two N. gonorrhoeae isolates with decreased ceftriaxone susceptibility in Thailand. Among 134 N. gonorrhoeae isolates collected from Thai Red Cross Anonymous Clinic, Bangkok, two isolates (NG-083 and NG-091) from urethral swab in male heterosexual patients had reduced susceptibility to ceftriaxone (MICs of 0.125 mg/L). Both were multidrug resistant and strong biofilm producers with ceftriaxone tolerance (MBEC > 128 mg/L). NG-083 and NG-091 remained susceptible to azithromycin (MIC of 1 mg/L and 0.5 mg/L, respectively). Reduced susceptibility to ceftriaxone was associated with alterations in PBP2, PBP1, PorB, MtrR, and mtrR promoter region. NG-083 belonged to sequence type (ST) 7235 and NG-091 has new allele number of tbpB with new ST. Molecular docking revealed ceftriaxone weakly occupied the active site of mosaic XXXIV penicillin-binding protein 2 variant in both isolates. Molecular epidemiology results revealed that both isolates display similarities with isolates from UK, USA, and The Netherlands. These first two genetically related gonococcal isolates with decreased ceftriaxone susceptibility heralds the threat of treatment failure in Thailand, and importance of careful surveillance.

Impact of ceftriaxone and temocillin on fecal abundance of extended-spectrum ß-lactamase producing Escherichia coli in a mouse model.

BACKGROUND: Gut colonization by ESBL-producing Enterobacteriaceae (ESBL-PE) is widespread and is promoted by antibiotic exposure. Higher fecal abundance of ESBL-PE promotes the dissemination of the bacteria in the environment and is associated with increased risk of infection. Ceftriaxone and temocillin are commonly used antibiotics with a different activity on gut flora. Their impact on fecal abundance of ESBL-producing Enterobacteriaceae has not been studied. The objective of this study was to compare the propensity of ceftriaxone and temocillin to modify the abundance of ESBL-producing Escherichia coli in feces of colonized mice. METHODS: Mice received broad-spectrum antibiotics in order to disrupt their normal gut flora. A CTX-M-type ESBL-producing E. coli clinical isolate was then administered orally, leading to durable colonization. Thirty days later, mice received either temocillin or ceftriaxone with drinking water at a concentration simulating human intestinal exposure. Third-generation-cephalosporin resistant (3GCR) E. coli were enumerated in feces on selective medium before, 2 days and 10 days after the end of antibiotic exposure. The experiment was performed with two E. coli isolates with different temocillin minimum inhibitory concentrations. RESULTS: Exposure to ceftriaxone induced an increase in the fecal abundance of 3GCR E. coli. In contrast, temocillin had no effect or transiently decreased the number of 3GCR E. coli. Results obtained with the two strains were similar. CONCLUSION: Contrary to ceftriaxone, temocillin does not promote expansion of ESBL-producing E. coli in feces of colonized mice. Thus temocillin may be a therapeutic of choice when a temocillin-susceptible strain infection is suspected or proven to prevent the expansion of ESBL-PE in a previously colonized patient.

Changes in the glutamate biomarker expression in rats vulnerable or resistant to the rewarding effects of cocaine and their reversal by ceftriaxone.

Literature data show diverse vulnerability to the rewarding effects of cocaine in human as well as in laboratory animals. The molecular mechanisms of these differences have not been discovered yet. While the initial effects of cocaine depend primarily on the dopamine system, numerous studies have shown that adaptation within the glutamatergic system is responsible for the development of addiction. In this paper, we used the unbiased conditioned place preference (CPP) to identify rats showing a vulnerable or resistant phenotype to the rewarding effects of cocaine. Next, we investigated the expression of membrane glutamate transporter proteins: GLT-1 and xCT in selected brain structures in the above-mentioned groups of rats. Moreover, we determined the nuclear level of NF-κB and Nrf2 to verify whether changes in GLT-1 and xCT expression correlate with NF-κB and Nrf2 levels, respectively. In addition, we determined GLT-1, NF-κB, xCT and Nrf2 mRNA levels to verify the involvement of transcriptional mechanisms. We also analyzed the ability of the ß-lactam antibiotic, ceftriaxone, to attenuate the persistence of CPP after a cocaine-free period in animals showing vulnerability to cocaine rewarding effects, and furthermore we determined GLT-1, xCT, NF-κB and Nrf2 protein expression. Our findings demonstrated molecular and neurochemical differences in the response to cocaine administration that are characteristic of the phenotype vulnerable or resistant to the rewarding effects of cocaine. Moreover, repeated administrations of ceftriaxone during cocaine-free perios attenuated CPP persistence and normalized GLT-1 level in the NAc. The results suggest the a lack of NF-κB involvement in the regulation of GLT-1 expression by ceftriaxone in the NAc. Additionally, we are the first to report that ceftriaxone strongly upregulates the GLT-1 in the HIP in a transcriptional mechanism involving the Nf-κB transcription factor. Future experiments may resolve the question concerning whether modulation exclusively of the GLT-1 expression in the HIP may attenuate cocaine-induced place preference or relapse.

Dynamic interactions of ceftriaxone and environmental variables suppress amphetamine seeking.

Extrasynaptic glutamate within the nucleus accumbens (NAc) is a driver of relapse. Cocaine, ethanol, and methamphetamine reduce the expression of cystine-glutamate antiporter (xCT) and primary glial glutamate transporter 1 (GLT1) leading to increased extrasynaptic glutamate. Ceftriaxone (CTX) restores xCT and GLT1 expression and effectively suppresses cocaine and ethanol reinstatement, however, the effects of CTX on amphetamine (AMP) reinstatement are not determined. Rodents were reared in an enriched condition (EC), isolated (IC), or standard condition (SC) and trained in AMP self-administration (0.1 mg/kg/infusion). EC, IC, and SC rats received injections of SAL or CTX (200 mg/kg) after daily extinction sessions. Then rats were tested in cue- and AMP-induced reinstatement tests. We hypothesized that EC rearing would reduce reinstatement by altering GLT1 or xCT expression in the NAc and medial prefrontal cortex (mPFC). In Experiment 2, pair-housed rats received once-daily AMP (1.0 mg/kg i.p.) or SAL for eight days followed by once-daily CTX (200 mg/kg i.p.) or SAL injections for 10 days. CTX treatment reduced cue-induced drug seeking in EC rats but not IC or SC rats. In an AMP-induced reinstatement test, CTX reduced AMP-induced drug seeking in EC and SC rats, but not IC rats. Western blot analyses revealed that AMP self-administration and non-contingent repeated AMP exposure did not downregulate GLT1 or xCT in the NAc or mPFC. Therefore, the ability for EC housing to reduce amphetamine seeking may work through other mechanisms.

The esterase B from Sphingobium sp. SM42 has the new de-arenethiolase activity against cephalosporin antibiotics.

The esterase B (EstB) from Sphingobium sp. SM42, which was previously reported to be active towards dibutyl phthalate, can cleave some small aromatic ring side chains from cephalosporin derivatives. A new name, de-arenethiolase, has been proposed to represent this activity. We present the in vitro characterization of the activity of purified EstB toward cephalosporin substrates. Interestingly, EstB was highly active against cefoperazone and cefazolin resulting in 83 and 67% decreases in killing zone diameter, respectively. EstB also demonstrated a moderate activity towards ceftriaxone (18%) and cefotaxime (16%) while exhibiting no activity against cephalosporin C and cefixime. HPLC analysis indicated that EstB catalyzed the cleavage of the C-S bond found in cephalosporin derivatives to release the corresponding free aromatic ring side chains.

Plasma and peritoneal fluid concentrations of ceftriaxone after intravenous and intraperitoneal administration in horses.

Intraperitoneal (IP) use of antimicrobial agents may lead to therapeutic effects with better clinical results than intravenous (IV) administration. The aim of this study was to compare plasma and peritoneal fluid concentrations of ceftriaxone after IP and IV administration in horses, and to evaluate possible adverse effects. One group of five horses received 25mg/kg ceftriaxone diluted in 1L saline solution by IP catheter once daily for 5 days, while a second group of five horses received 25mg/kg ceftriaxone diluted in 250mL saline solution by IV injection once daily for 5days and 1L saline solution by IP catheter once daily for 5 days. Peritoneal fluid and plasma were collected to determine ceftriaxone concentrations after the first and fifth administration. IP administration of ceftriaxone resulted in concentrations above a minimum inhibitory concentration (MIC) of 1µg/mL for 24h in peritoneal fluid and for 12h in plasma, while IV administration of ceftriaxone resulted in lower peritoneal fluid concentrations, which remained above a MIC of 1µg/mL for 12h in peritoneal fluid and 10h in plasma. No adverse effects were observed. Comparisons of ceftriaxone concentrations, time of occurrence of the maximum (Tmax) and minimum (Tmin) concentrations, and the mean residence time (MRT), between the two groups showed that IP administration provided greater availability of cephalosporin in peritoneal fluid. The IP use of ceftriaxone (25mg/kg diluted in 1L saline solution once daily) may be useful for the prophylaxis and/or treatment of peritonitis in horses.

Statistically optimized ceftriaxone sodium biotransformation through Achromobacter xylosoxidans strain Cef6: an unusual insight for bioremediation.

The present study underlines a unique promising approach toward efficient biotransformation of ceftriaxone sodium (Ceftx), a highly frequent prescribed cephalosporin antibiotic, by a newly bacterium namely Achromobacter xylosoxidans strain Cef6 isolated from Ceftx contaminated raw materials in pharmaceutical industries. A three step sequential statistical-mathematical approach (Plackett-Burman design [PBD], Central Composite Design [CCD], and ridge-canonical analyses) was anticipated to optimize the biotransformation process. Ceftx concentration and medium volume: bottle volume ratio, two key determinants, significantly (p < 0.05) affected the process outcome deduced by regression analysis of PBD' data. CCD and ridge-canonical analyses localized the optimal levels of Ceftx concentration and medium volume: 250 ml bottle volume ratio to be 0.39 and 7.973 g Ceftx/L modified tryptic soy broth achieving Ceftx biotransformation (100%) after 39 h under aerobic static conditions at 30 °C, irrespectively deduced via HPLC analysis. Impressively, only one of five Ceftx byproducts was detected by the end of the biotransformation process. To the best of authors' knowledge, this is the first report addressing a detailed study regarding efficient biotransformation of Ceftx by single bacterium not bacterial consortium under aerobic conditions. Present data would greatly encourage applying this approach for decontamination of some Ceftx contaminated environmental sites.

Metallo-ß-lactamase Domain-Containing Protein 1 (MBLAC1) Is a Specific, High-Affinity Target for the Glutamate Transporter Inducer Ceftriaxone.

Ceftriaxone, a ß-lactam antibiotic, has been reported to act independently of its antimicrobial actions to normalize perturbed central nervous system glutamate levels, principally by elevating expression of glial glutamate transporters. Identification of a specific, high-affinity target for ceftriaxone could significantly impact therapeutic development for multiple brain disorders, ranging from neurodegenerative disorders to addiction. Recently, we identified a glial-expressed Caenorhabditis elegans gene, swip-10, that encodes a metallo-ß-lactamase domain-containing protein, and limits glutamate-dependent changes in dopamine neuron excitability. Bioinformatic analyses identified MBLAC1 as the likely mammalian orthologue of swip-10. Using cyanogen bromide immobilized ceftriaxone for affinity capture experiments and backscattering interferometry to monitor MBLAC1 binding of unmodified ceftriaxone, we obtained evidence for specific, high affinity (KD = 2.2 µM) binding of ceftriaxone to MBLAC1. We discuss our findings with respect to MBLAC1 as a potentially exclusive, high-affinity binding partner of ceftriaxone in the CNS, and the path forward in the development of novel, MBLAC1-based therapeutics.

Research Progress of Mechanisms of Ceftriaxone Associated Nephrolithiasis.

BACKGROUND: Urinary calculi can be caused by a variety of reasons, such as metabolic abnormalities, urinary tract infection and obstruction. Certain medications can induce urinary stone disease. Ceftriaxone, a third generation cephalosporin with broad spectrum antibiotic activity, primarily eliminated by the kidneys, has now been widely used for treatment of infection. It has been long considered safe, especially in children. However, more and more cases about ceftriaxone induced nephrolithiasis as a rare side effect have been reported. CONCLUSION: This complication generally resolves spontaneously with cessation of the drug. Severe nephrolithiasis can cause post renal acute renal failure (PARF). There is limited information about how this complication develops, though high doses and extended treatment periods are generally considered to be responsible. Understanding the mechanisms would help the doctors to be aware of this rare complication and respond with proper treatment. The primary goal of this review is to discuss the possible mechanisms based on the most recent literatures.

Pharmacokinetics of ceftriaxone in plasma and bone of patients undergoing hip or knee surgery.

OBJECTIVES: Patients undergoing hip or knee replacement therapy are routinely pretreated with antibiotics before surgery. It is controversial in which antibiotic is the treatment of choice for this purpose. One possibility is the cephalosporin ceftriaxone. Here, we wanted to know if effective tissue concentrations are reached. METHODS: We studied plasma and bone kinetics of ceftriaxone in orthopaedic patients (n = 22) treated with ceftriaxone (2 g) immediately prior operation. Plasma samples were withdrawn before and at three time points after ceftriaxone infusion. After bone replacement, extracts from cancellous bone or cortical bone were obtained, and ceftriaxone was quantified using column chromatography. KEY FINDINGS: The plasma kinetics of ceftriaxone and distribution into bone were analysed using a population approach (ADAPT 5). The population mean of the area under the curve (AUC) was 140 mg h/l. A cancellous bone to plasma concentration ratio of 1.12 ± 1.29 was achieved 5 h after start of infusion. The half-life of uptake into the cortical bone was less (8.4 h) than into cancellous bone (12.1 h, P < 0.05). CONCLUSIONS: Under these experimental conditions, concentrations of ceftriaxone in cancellous and cortical bone should be adequate to protect the patients against usual ceftriaxone-sensitive nosocomial infections and are substantially lower than the plasma concentrations.

Gastrointestinal colonization with a cephalosporinase-producing bacteroides species preserves colonization resistance against vancomycin-resistant enterococcus and Clostridium difficile in cephalosporin-treated mice.

Antibiotics that are excreted into the intestinal tract may disrupt the indigenous intestinal microbiota and promote colonization by health care-associated pathogens. ß-Lactam, or penicillin-type, antibiotics are among the most widely utilized antibiotics worldwide and may also adversely affect the microbiota. Many bacteria are capable, however, of producing ß-lactamase enzymes that inactivate ß-lactam antibiotics. We hypothesized that prior establishment of intestinal colonization with a ß-lactamase-producing anaerobe might prevent these adverse effects of ß-lactam antibiotics, by inactivating the portion of antibiotic that is excreted into the intestinal tract. Here, mice with a previously abolished microbiota received either oral normal saline or an oral cephalosporinase-producing strain of Bacteroides thetaiotaomicron for 3 days. Mice then received 3 days of subcutaneous ceftriaxone, followed by either oral administration of vancomycin-resistant Enterococcus (VRE) or sacrifice and assessment of in vitro growth of epidemic and nonepidemic strains of Clostridium difficile in murine cecal contents. Stool concentrations of VRE and ceftriaxone were measured, cecal levels of C. difficile 24 h after incubation were quantified, and denaturing gradient gel electrophoresis (DGGE) of microbial 16S rRNA genes was performed to evaluate the antibiotic effect on the microbiota. The results demonstrated that establishment of prior colonization with a ß-lactamase-producing intestinal anaerobe inactivated intraintestinal ceftriaxone during treatment with this antibiotic, allowed recovery of the normal microbiota despite systemic ceftriaxone, and prevented overgrowth with VRE and epidemic and nonepidemic strains of C. difficile in mice. These findings describe a novel probiotic strategy to potentially prevent pathogen colonization in hospitalized patients.

Studies of the drug resistance response of sensitive and drug-resistant strains in a microfluidic system.

Since the discovery of bacterial drug resistance, its dynamics have been the focus in biophysics studies. In this paper, we used a new microfluidic system to monitor the responses of sensitive and drug-resistant strains of E. coli in different ß-lactam ceftriaxone concentrations at the single cell level and traced each individual cell's states such as cell length, GFP protein expression and growth rate. The ß-lactamase production of the drug-resistant strain is quantified by fluorescence intensity, as the GFP gene co-transcribes with the enzyme expression gene. Our results show that the drug-resistant strain can endure a much higher concentration of antibiotics than the sensitive strain and has an antibiotic concentration ratio from the cell death state to the cell elongation state that is much larger than that of the sensitive strain. The single cell data and simulation suggest that bacteria with slower growth rates have higher drug resistance both in the sensitive and drug-resistant strains. The drug-resistant strain shows adaptation behavior, but no adaptation is found in the sensitive strain after changing to a high antibiotic concentration. A mathematical model of cell growth can qualitatively explain the observed behavior. The quantitative measurement of single-cell phenotype changes and dynamic analysis presented in this study should shed light on the antibiotic process of different bacteria.

Impact of extended-spectrum beta-lactamase on acute pyelonephritis treated with empirical ceftriaxone.

BACKGROUND: Ceftriaxone is frequently administered empirically for hospitalized patients with acute pyelonephritis (APN) due to prevalent quinolone resistance in our hospital; however, its use is inappropriate for extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli, an increasing problem. METHODS: A retrospective, 1:2 matched cohort study was performed to evaluate the impact of ESBL on APN treated with empirical ceftriaxone. Each patient in ESBL group was matched with two patients in the non-ESBL group, using a 16-point scoring system, which included age, sex, bacteremia, simplified acute physiology score 2, Charlson comorbidity index and APN severity score. RESULTS: From 2009 to 2011, among 1,322 community-onset cases of the E. coli bacteriuria with 212 (16%) ESBL producers, 261 patients with APN were treated empirically with ceftriaxone in a secondary care hospital. Among these 261 cases, twenty-six patients in the ESBL group and 52 matched patients in the non-ESBL group (1:2) were included. Mean time to defervescence was 4.6±2.2 days in the ESBL group and 2.6±1.3 days in the non-ESBL group (p<0.01). Rate of microbiological resolution within 5 days after antibiotic treatment was 77% (17/22) in the ESBL group and 100% (45/45) in the non-ESBL group (p=0.01). The duration of hospitalization was 13.3±8.2 days in the ESBL group and 7.3±3.5 days in the non-ESBL group (p<0.01). No patient died in either group. CONCLUSION: Empirical ceftriaxone therapy for APN caused by ESBL-producing E. coli is inappropriate, and consequently can delay recovery and result in longer hospitalization.