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Query: UMLS:C0032285 (pneumonia)
 54,520 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

128 isolates of Acinetobacter species from admitted and outdoor patients were subjected to biotyping and resistotyping. Resistance phenotype analysis included nine antibiotics and two betalactam inhibitor combination drugs. In 100 strains of Acinetobacter spp. ciprofloxacin, amikacin, cefotaxime and cefepime minimum inhibitory concentration (MIC) was done by agar dilution using NCCLS 2002 criteria. In forty-nine isolates MIC level was determined by E-strip also. Extended spectrum beta lactamase (ESBL) production was detected by double disc synergy technique. Inducible beta lactamases (IBL's) were detected by disc approximation method. The relationship between biotypes and resistance phenotype was analyzed. Majority of isolates (93.75%) were from admitted patients. The biotyping revealed Acinetobacter calcoaceticus-Acinetobacter baumannii complex (87.2%) to be the predominant species and they were isolated from tracheal aspirates of patients with ventilator associated pneumonia. By Kirby Bauer disc diffusion antimicrobial sensitivity testing Acinetobacter spp. were most sensitive to the combination of drug cefoperazone-sulbactam (95.6%) followed by meropenem (94.6%), piperacillin-tazobactam (92.6%). On screening incidence of Imipenem Nonsensitive Acinetobacter spp. (INSA) was (5.4%). Acinetobacter spp. were typable by six resistance phenotypes and six biotypes. Most common (66.6%) resistant phenotype of A. calcoaceticus-A. baumannii complex was susceptible to cefoperazone-sulbactam and or meropenem and or piperacillin-tazobactam. ESBL production was seen in 6% and IBL (Inducible Beta Lactamase) production was seen in 7% of Acinetobacter spp. The MIC90 for ciprofloxacin was =256 microg/ml, cefotaxime 512 microg/ml, cefepime 512 microg/ml, and amikacin 32 microg/ml. Multidrug resistance was seen in more than 90% of A. calcoaceticus-A. baumannii complex and 20% of Acinetobacter lwoffii. Acinetobacter spp. has other emerging novel mechanism of resistance that requires continuous research. Simpler, reproducible and reliable methods of biotyping and their subsequent correlation with resistotyping are more cost effective than molecular methods, which are available only in reference laboratories.
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PMID:Characterization and changing minimum inhibitory concentration (MIC) of Acinetobacter species from a tertiary care setup. 1674 72

The concomitant use of low concentration beta-lactam antibiotics antagonizes the activity of vancomycin against some strains of MRSA. These strains, called beta-lactam antibiotic-induced vancomycin resistant MRSA (BIVR), have been increasing for a number of years. We previously reported that the combination of VCM and ceftizoxime displayed this antagonism not only in vitro, but also in vivo, in a systemic infection caused by BIVR in mice. In the present study, we validated the antagonism in combinations of VCM with other beta-lactams, i.e., flomoxef (FMOX), ampicillin (AMPC), azthreonam (AZT) and imipenem/cilastatin (IPM/CS), in systemic infections and pneumoniain in mice. The survival rate of the mice with systemic infections caused by BIVR treated with combinations of FMOX, AMPC, AZT, and IPM/CS with VCM were significantly lower than with VCM monotherapy, and the number of residual viable cells in the kidneys of mice treated with combinations of FMOX and IPM/CS with VCM were significantly higher than with VCM monotherapy The number of residual viable cells in the lungs of mice with pneumonia caused by BIVR treated with the combination of IPM/CS and VCM was significantly higher than with VCM monotherapy. On the other hand, the survival rate with combination therapy consistings IPM/CS plus teicoplanin (T EIC) was significantly higher, and the number of residual viable cells in the kidney was significantly lower, than with TEIC monotherapy alone. In the mice with pneumonia, the number of residual viable cells in the lung after combination therapy with IPM/CS and TEIC was significantly lower than with TEIC monotherapy. Combination therapy with beta-lactams plus VCM showed antagonistic in models of systemic infection and pulmonary infection caused by BIVR, whereas combination therapy consisting of a beta-lactam plus TEIC had a synergistic effect in the same models, even though VCM and TEIC are member of the same glycopeptide antibiotic class.
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PMID:[Combined effect of vancomycin or teicoplanin plus a beta-lactam antibiotic in mouse infection models caused by beta-lactam antibiotec-induced vancomycin resistant MRSA (BIVR)]. 1678 Jan 31

Imipenem, the first carbapenem discovered, was developed more than two decades ago in response to an unmet need for a highly potent, broad-spectrum antimicrobial agent with a strong safety profile. It has since been used to treat more than 26 million patients. In an era where antibiotic use has driven antibiotic resistance, choosing appropriate initial therapy for serious infection is critical. Appropriate antibiotic regimens must cover all likely pathogens, be administered promptly at the correct dosage and dosing interval, be well tolerated and prevent the emergence of resistance. While imipenem was initially reserved for use in intractable, serious infections, the benefits of early aggressive therapy are now known, making imipenem a core agent in de-escalation therapy due to proven efficacy and safety for indications such as nosocomial pneumonia, intra-abdominal infection, sepsis and febrile neutropenia. De-escalation therapy with an agent such as imipenem minimizes resistance development by initiating aggressive initial treatment and then tailoring therapy based on patient response and culture results, switching to a less expensive, narrower spectrum antibiotic regimen or shortening the duration of therapy. Imipenem has maintained sustained clinical efficacy, tolerability and in vitro activity against important bacterial pathogens for two decades. We review the factors that continue to make imipenem as appropriate an agent for de-escalation therapy now as it was 20 years ago.
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PMID:Two decades of imipenem therapy. 1699 45

Intubated patients frequently become colonized by Pseudomonas aeruginosa, which is subsequently responsible for ventilator-associated pneumonia. This pathogen readily acquires resistance against available antimicrobials. Depending on the resistance mechanism selected for, resistance might either be lost or persist after removal of the selective pressure. We investigated the rapidity of selection, as well as the persistence, of antimicrobial resistance and determined the underlying mechanisms. We selected 109 prospectively collected P. aeruginosa tracheal isolates from two patients based on their prolonged intubation and colonization periods, during which they had received carbapenem, fluoroquinolone (FQ), or combined beta-lactam-aminoglycoside therapies. We determined antimicrobial resistance phenotypes by susceptibility testing and used quantitative real-time PCR to measure the expression of resistance determinants. Within 10 days after the initiation of therapy, all treatment regimens selected resistant isolates. Resistance to beta-lactam and FQ was correlated with ampC and mexC gene expression levels, respectively, whereas imipenem resistance was attributable to decreased oprD expression. Combined beta-lactam-aminoglycoside resistance was associated with the appearance of small-colony variants. Imipenem and FQ resistance persisted for prolonged times once the selecting antimicrobial treatment had been discontinued. In contrast, resistance to beta-lactams disappeared rapidly after removal of the selective pressure, to reappear promptly upon renewed exposure. Our results suggest that resistant P. aeruginosa is selected in less than 10 days independently of the antimicrobial class. Different resistance mechanisms lead to the loss or persistence of resistance after the removal of the selecting agent. Even if resistant isolates are not evident upon culture, they may persist in the lung and can be rapidly reselected.
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PMID:Development and persistence of antimicrobial resistance in Pseudomonas aeruginosa: a longitudinal observation in mechanically ventilated patients. 1726 19

The carbapenems are beta-lactam antimicrobial agents with an exceptionally broad spectrum of activity. Older carbapenems, such as imipenem, were often susceptible to degradation by the enzyme dehydropeptidase-1 (DHP-1) located in renal tubules and required co-administration with a DHP-1 inhibitor such as cilastatin. Later additions to the class such as meropenem, ertapenem and doripenem demonstrated increased stability to DHP-1 and are administered without a DHP-1 inhibitor. Like all beta-lactam antimicrobial agents, carbapenems act by inhibiting bacterial cell wall synthesis by binding to and inactivating penicillin-binding proteins (PBPs). Carbapenems are stable to most beta-lactamases including AmpC beta-lactamases and extended-spectrum beta-lactamases. Resistance to carbapenems develops when bacteria acquire or develop structural changes within their PBPs, when they acquire metallo-beta-lactamases that are capable of rapidly degrading carbapenems, or when changes in membrane permeability arise as a result of loss of specific outer membrane porins. Carbapenems (imipenem, meropenem, doripenem) possess broad-spectrum in vitro activity, which includes activity against many Gram-positive, Gram-negative and anaerobic bacteria; carbapenems lack activity against Enterococcus faecium, methicillin-resistant Staphylococcus aureus and Stenotrophomonas maltophilia. Compared with imipenem, meropenem and doripenem, the spectrum of activity of ertapenem is more limited primarily because it lacks activity against Pseudomonas aeruginosa and Enterococcus spp. Imipenem, meropenem and doripenem have in vivo half lives of approximately 1 hour, while ertapenem has a half-life of approximately 4 hours making it suitable for once-daily administration. As with other beta-lactam antimicrobial agents, the most important pharmacodynamic parameter predicting in vivo efficacy is the time that the plasma drug concentration is maintained above the minimum inhibitory concentration (T>MIC). Imipenem/cilastatin and meropenem have been studied in comparative clinical trials establishing their efficacy in the treatment of a variety of infections including complicated intra-abdominal infections, skin and skin structure infections, community-acquired pneumonia, nosocomial pneumonia, complicated urinary tract infections, meningitis (meropenem only) and febrile neutropenia. The current role for imipenem/cilastatin and meropenem in therapy remains for use in moderate to severe nosocomial and polymicrobial infections. The unique antimicrobial spectrum and pharmacokinetic properties of ertapenem make it more suited to treatment of community-acquired infections and outpatient intravenous antimicrobial therapy than for the treatment of nosocomial infections. Doripenem is a promising new carbapenem with similar properties to those of meropenem, although it appears to have more potent in vitro activity against P. aeruginosa than meropenem. Clinical trials are required to establish the efficacy and safety of doripenem in moderate to severe infections, including nosocomial infections.
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PMID:Comparative review of the carbapenems. 1748 46

Beta-lactams are regularly administered in intermittent short-term infusions. The percentage of the dosing interval during which free drug concentrations exceed the MIC (fT(>MIC)) is the measure of drug exposure that best correlates with clinical outcome for beta-lactams. Therefore, administration by continuous infusion has gained increasing interest recently. We studied 20 critically ill patients with nosocomial pneumonia and investigated whether continuous infusion with a reduced total dose, compared to the standard regimen of intermittent short-term infusion, results in a superior probability of target attainment as assessed by the fT(>MIC) value of imipenem. In this prospective, randomized, controlled clinical study, patients received either a loading dose of 1 g/1 g imipenem and cilastatin (as a short-term infusion) at time zero, followed by 2 g/2 g imipenem-cilastatin per 24 h as a continuous infusion for 3 days (n = 10), or 1 g/1 g imipenem-cilastatin three times per day as a short-term infusion for 3 days (total daily dose, 3 g/3 g; n = 10). Imipenem concentrations in plasma were determined by using a validated liquid chromatography-tandem mass spectrometry assay. A two-compartment open model was employed for population pharmacokinetic modeling. We simulated 10,000 intensive-care-unit patients via Monte Carlo simulations for pharmacodynamic evaluation using the target 40% fT(>MIC). The probability of target attainment by MIC for intermittent infusion was robust (>90%) up to MICs of 1 to 2 mg/liter. The corresponding value for continuous infusion was 2 to 4 mg/liter. Although all 20 patients had an fT(>MIC) of 100%, 3 patients died. Patient survival was best described by employing a sepsis-related organ failure assessment score as a covariate in a logistic regression analysis. Larger clinical trials are warranted for evaluation of continuous infusions at a reduced dose of imipenem for critically ill patients.
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PMID:Population pharmacokinetics and pharmacodynamics of continuous versus short-term infusion of imipenem-cilastatin in critically ill patients in a randomized, controlled trial. 1762 Mar 71

Sensitivity to beta-lactam antibiotics of isolates clinically obtained from respiratory infection sites in adults on the second survey on sensitivity of isolates conducted by the Japanese Society of Chemotherapy in 2007 was investigated according to the classification of the "Guideline for treatment for adult nosocomial pneumonia in 2008". Among the primary antibacterial drugs for mild (A) and moderate (B) nosocomial pneumonia in adults, beta-lactam antibiotics; ceftriaxone (CTRX), sulbactam/ampicillin (SBT/ABPC), panipenem/betamipron (PAPM/BP), tazobactam/piperacillin (TAZ/PIPC), imipenem/cilastatin (IPM/CS), meropenem (MEPM), doripenem (DRPM), biapenem (BIPM) were studied to evaluate their clinical efficacy. The covering rate was analyzed using the minimal inhibitory concentration (MIC) and break point of pharmacokinetics/pharmacodynamics (PK/PD). Consequently, the results with methicillin-susceptible Staphylococcus aureus (MSSA), Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Klebsiella pneumoniae revealed the MIC90 of all antibacterial drugs to be at low levels, while almost 100% of isolates were within the range of PK/PD break points except BIPM and SBT/ABPC to H. influenzae, and SBT/ABPC to K. pneumoniae. However, the analysis of P. aeruginosa didn't reach 100% for the covering rates of isolates, indicating that these drugs did not have a complete inhibitory action to restrict bacterial proliferation. The analysis of all 5 carbapenem drugs showed superiority to TAZ/PIPC in MIC90 while covering rates of isolates at PK/PD break points showed inferiority to TAZ/PIPC. This tendency was found to be more significant in covering the rates of isolates on the regular dose with maximal bactericidal action and on the maximum dose. This is because the maximum dose approved in Japan is as low as half that in IPM/CS and 1/3 that in MEPM in Western countries.
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PMID:[Analysis on the sensitivity to beta-lactam antibiotics of respiratory-infectious isolates on the second survey on the sensitivity of isolates conducted by the Japanese Society of Chemotherapy in 2007--concerning the aspect of PK/PD break points]. 1988 81

There are currently no defined optimal therapies available for multidrug-resistant (MDR) Acinetobacter baumannii infections. We evaluated the efficacy of rifampin, imipenem, sulbactam, colistin, and their combinations against MDR A. baumannii in experimental pneumonia and meningitis models. The bactericidal in vitro activities of rifampin, imipenem, sulbactam, colistin, and their combinations were tested using time-kill curves. Murine pneumonia and rabbit meningitis models were evaluated using the A. baummnnii strain Ab1327 (with MICs for rifampin, imipenem, sulbactam, and colistin of 4, 32, 32, and 0.5 mg/liter, respectively). Mice were treated with the four antimicrobials and their combinations. For the meningitis model, the efficacies of colistin, rifampin and its combinations with imipenem, sulbactam, or colistin, and of imipenem plus sulbactam were assayed. In the pneumonia model, compared to the control group, (i) rifampin alone, (ii) rifampin along with imipenem, sulbactam, or colistin, (iii) colistin, or (iv) imipenem plus sulbactam significantly reduced lung bacterial concentrations (10.6 +/- 0.27 [controls] versus 3.05 +/- 1.91, 2.07 +/- 1.82, 2.41 +/- 1.37, 3.4 +/- 3.07, 6.82 +/- 3.4, and 4.22 +/- 2.72 log(10) CFU/g, respectively [means +/- standard deviations]), increased sterile blood cultures (0% versus 78.6%, 100%, 93.3%, 93.8%, 73.3%, and 50%), and improved survival (0% versus 71.4%, 60%, 46.7%, 43.8%, 40%, and 85.7%). In the meningitis model rifampin alone or rifampin plus colistin reduced cerebrospinal fluid bacterial counts (-2.6 and -4.4 log(10) CFU/ml). Rifampin in monotherapy or with imipenem, sulbactam, or colistin showed efficacy against MDR A. baumannii in experimental models of pneumonia and meningitis. Imipenem or sulbactam may be appropriate for combined treatment when using rifampin.
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PMID:Efficacy of rifampin and its combinations with imipenem, sulbactam, and colistin in experimental models of infection caused by imipenem-resistant Acinetobacter baumannii. 2004 14

Severe sepsis defined as infection-induced organ dysfunction or hypoperfusion abnormalities predispose to septic shock and increased mortality in neutropenic setting. We aimed at determining predictors of severe sepsis in neutropenic patients. Between 1 October and 31 December 2007, 41 patients (21 with acute myeloid leukemia, 19 with acute lymphoid leukemia and one with autologous stem cell transplantation for a mantle cell lymphoma) with chemotherapy-induced neutropenia (<0.5 x 10(9)/l) lasting for more than 7 days were included in this study. The median age was 28 years (range: 3-58 years). All patients were on oral antibacterial (colistin and gentamicin) and anti-fungal (amphotericin B) prophylaxis. The first neutropenic febrile episode was treated with piperacillin/tazobactam and colistin IV; if the patient remains febrile at 48 h from the start of this first line of treatment, amphotericin B i.v. is added. Imipenem was introduced in the case of non-response and finally glycopeptides were introduced according to the IDSA criteria. Severe sepsis and septic shock are defined according to the criteria of the consensus conference of the ACCP/SCCM excluding the leukocyte count since all the patients were neutropenic. Ninety-four febrile episodes were observed: 27 microbiologically documented (28.7%), six clinically documented (6.3%) and 61 fever of unknown origin (65%). Microbiologically documented infections were: 13 Gram-negative organisms, 11 Gram-positive organisms and three combined (Gram+ and -). Clinically documented infections were pneumonia (two), neutropenic enterocolitis (one), sinuses infection (one) and cutaneous infection (two). Severe sepsis accounted for 22 febrile episodes. Factors associated with the occurrence of severe sepsis were: hypophosphatemia (<0.8 mmol/l; p=0.05, OR=3.9, 95% CI: 1.3-45.7), hypoproteinemia (<62 g/l; p=0.006, OR=4.1, 95% CI: 1.4-11.4) and non-adapted antibiotherapy at the onset of severe sepsis (p=0.019, OR=2.7, 95% CI: 1.02-7.39). However, heart rate/systolic blood pressure ratio <1.1 (p<0.001, OR=0.1, 95% CI: 0.03-0.31) and Creactive protein <80 mg (p=0.001, OR=0.14, 95% CI: 0.04-0.54) were not predictive.
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PMID:Factors associated with severe sepsis: prospective study of 94 neutropenic febrile episodes. 2013 59

The in vivo activity of tigecycline was evaluated in an experimental pneumonia model (C57BL/6 mice) by Acinetobacter baumannii. Two clinical strains were used: minimum inhibitory concentrations (MICs) of imipenem and tigecycline 1 and 2 microg/mL (imipenem-susceptible, IPM-S), and 8 and 2 microg/mL (imipenem-intermediate, IPM-I), respectively. For imipenem (30 mg/Kg), T/CMI (h) were 1.04 and 0.51 for IPM-S and IPM-I, respectively. For tigecycline (5 mg/Kg), the area under the concentration-time curve (AUC)/MIC(0-24 h) (serum and lung) were 9.24 and 4.37 (for the two strains), respectively. In the efficacy experiments with the IPM-S, imipenem (log CFU/g 3.59 +/- 0.78, p = 0.006) and tigecycline (2.82 +/- 1.2, p = 0.054) decreased the bacterial counts in lungs with respect to its controls; with the IPM-I, both imipenem (1.21 +/- 0.52, p = 0.002) and tigecycline (3.21 +/- 0.28, p = 0.035) decreased the bacterial counts with respect to the controls. In the survival experiments, with the IPM-S, the mortality was the same in the control (67%) and in the tigecycline (77%) groups, and imipenem reduced it (21%, p = 0.025); with the IPM-I, the mortality was the same in the control (87%) and in the tigecycline (85%) groups, and imipenem (0%) reduced it (p < 0.001). In summary, the present study shows that tigecycline is less efficacious than imipenem in the treatment of experimental A. baumannii pneumonia caused by IPM-S and IPM-I strains.
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PMID:Efficacy of tigecycline vs. imipenem in the treatment of experimental Acinetobacter baumannii murine pneumonia. 2018 60


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