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Query: UMLS:C0348321 (Haemophilus)
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Hospital microbiology laboratories from 41 states participated in a bacterial antimicrobial susceptibility study comparing in vitro results generated by the standardized disk diffusion method. Over 41,000 freshly isolated aerobic and facultative strains, representing all specimen types (except stools and urines), were tested for their susceptibility to piperacillin-tazobactam and 21 other antimicrobial agents. Enterococcus spp. was the second or third most common isolate from intraabdominal, gynecologic, and cutaneous infections, confirming its growing importance as a nosocomial pathogen. Escherichia coli was the most frequent isolate overall, despite the exclusion of urinary tract specimens from the study. Pseudomonas aeruginosa was the second most prevalent species, ranking first in frequency of recovery from lower-respiratory-tract specimens. Piperacillin-tazobactam was the most active beta-lactamase inhibitor combination tested against Gram-negative bacteria. Its activity against Gram-positive bacteria and Haemophilus influenzae was similar to that of ampicillin-sulbactam (95-97% susceptible). Imipenem and piperacillin-tazobactam displayed similar spectrums of activity against Gram-positive organisms and Haemophilus influenzae. Against Enterobacteriaceae, piperacillin-tazobactam and ceftazidime exhibited similarly wide spectrums of activity, but with some gaps, particularly among Enterobacter spp. and Citrobacter freundii. In this large-scale in vitro study, piperacillin-tazobactam and imipenem displayed the widest antimicrobial spectrums, inhibiting > 90% of all isolates tested.
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PMID:National survey of the in vitro spectrum of piperacillin-tazobactam tested against more than 40,000 aerobic clinical isolates from 236 medical centers. 764 35

Piperacillin combined with tazobactam at a fixed concentration (4 micrograms/ml) and a ratio (8:1) was tested against 5,029 aerobic isolates and 447 fastidious organisms, including anaerobes. Among the Enterobacteriaceae, > 95% inhibition was shared only by imipenem (99.1% at < or = 4 micrograms/ml), and some newer cephalosporins (95.1% - 99.8% at < or = 8 micrograms/ml), and piperacillin-tazobactam (95.8% at < or = 16/4 micrograms/ml). Piperacillin-tazobactam was the most active agent tested against nonenteric Gram-negative bacilli (93.5% at < or = 8 micrograms/ml). Ampicillin-sulbactam was the most active agent against staphylococci (95.0% at < or = 8 micrograms/ml), followed by imipenem (91.8%), piperacillin-tazobactam (89.3% at < or = 8/4 micrograms/ml), and cefepime (86.2% at < or = 8 micrograms/ml). Against the enterococci, only ampicillin (93.0% at < or = 8 micrograms/ml) with or without sulbactam, piperacillin (91.0% at < or = 16 micrograms/ml) with or without tazobactam, and imipenem (91.0%) had acceptable activity. Piperacillin-tazobactam and imipenem were the most active drugs tested against all aerobic isolates, inhibiting 93.5% of isolates each. Piperacillin-tazobactam inhibited all fastidious isolates tested, including Haemophilus influenzae (MIC90, 0.094/4 micrograms/ml), Moraxella catarrhalis (MIC90, 0.064/4 micrograms/ml), Neisseira gonorrhoeae (MIC90, < or = 0.016/4 micrograms/ml), and Streptococcus pneumoniae (all MICs, < or = 4/4 micrograms/ml). Against the anaerobic isolates, the most broad-spectrum antimicrobial agents tested were imipenem (100.0%), piperacillin-tazobactam (99.5% at < or = 32/4 micrograms/ml), metronidazole (98.4% at < or = 8 micrograms/ml), and ticarcillin-clavulanic acid (95.1% at < or = 32/2 micrograms/ml). These results are nearly identical to a previous study involving the same five medical centers in 1989. Piperacillin-tazobactam appears to remain a highly effective beta-lactamase inhibitor combination with a wide empiric spectrum and potency in teaching hospitals.
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PMID:Comparative antimicrobial activity of piperacillin-tazobactam tested against more than 5000 recent clinical isolates from five medical centers. A reevaluation after five years. 764 36

Tazobactam is a new, irreversible inhibitor of bacterial beta-lactamases of staphylococci, plasmid-mediated beta-lactamases of the TEM and SHV types found in Escherichia coli and Klebsiella species and beta-lactamases of anerobes such as Bacteroides species. Its combination with piperacillin, a broad spectrum ureido-penicillin, would be expected to improve the activity of piperacillin against staphylococci, TEM and SHV beta-lactamase producing Gram negative bacteria and anerobes. Minimal inhibitory concentrations (MIC) of piperacillin/tazobactam were determined for 1952 individual patient isolates of Gram positive and negative bacteria causing significant infections and compared with MIC values for cefotaxime, ceftazidime, ciprofloxacin, imipenem, ticarcillin/clavulanic acid. MICs were determined by agar dilution (NCCLS 1990 and 1992). Piperacillin/tazobactam had excellent activity against methicillin susceptible staphylococci, Streptococcus pneumoniae, Haemophilus influenzae, enterococci and organisms of the Bacteroides fragilis group. It was also active against the majority of Enterobacteriaceae and Pseudomonas aeruginosa isolates tested. It was not active against extended spectrum beta-lactamase (ESBL) producing Klebsiella species and some high level TEM and SHV beta-lactamase producing E. coli and Klebsiella species. Activity against Gram negative organisms capable of producing chromosomally mediated beta-lactamases was good, since in most organisms tested, the enzymes were not induced in sufficient quantities to cause antibiotic resistance. However some Enterobacter species were derepressed hyperproducing mutants; these isolates showed resistance to piperacillin/tazobactam since tazobactam does not inhibit these Class I beta lactamases. Activity was superior to ticarcillin/clavulanic acid for Gram negative rods. Imipenem was the most active agent against ESBL producing Klebsiella species. Piperacillin/tazobactam has a suitable spectrum of activity in vitro to suggest its use in monotherapy of mixed anerobic infections, mixed respiratory infections such as aspiration pneumonia and, in combination with an aminoglycoside, it would provide Gram positive as well as Gram negative cover of febrile episodes in immunosuppressed patients.
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PMID:An evaluation of the in vitro activity of piperacillin/tazobactam. 874 25

The in-vitro activity of piperacillin/tazobactum which is not among the routinely tested antibiotic at the Public Health Bacteriology Laboratory, Parirenyatwa Hospital, Harare, Zimbabwe was evaluated for its activity against bacterial pathogens using the Kirby-Bauer disk diffusion method. Piperacillin/tazobactum showed superior in-vitro activity against both gram positive and gram negative bacteria when compared with routinely tested antibiotics such as gentamicin, erythromycin, tetracycline, penicillin, chloramphenicol, fusidic acid and clindamycin and the difference was statistically significant (p < 0.05). Ciprofloxacin showed in-vitro activity comparable to that of tazobactam/piperacillin. Specifically, 96% of gram positive isolates (comprising Streptococcus pyogenes, Staphylococcus aureus, coagulase negative staphylococci and Streptococcus pneumoniae were sensitive to piperacillin/tazobactam. For gram negative organisms, 98% of Haemophilus influenzae Shigella spp, Klebsiella spp were also sensitive to the combination. The broad spectrum of activity of piperacillin/tazobactam shows that the potential of the drug combination for the treatment of infections caused by diverse microorganisms should not be underestimated. We recommend its inclusion in routine antibiotic sensitivity testing in our hospital.
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PMID:In-vitro activity of piperacillin and tazobactam combination against clinically significant bacteria. 964 Aug 15

The in vitro activity of piperacillin/tazobactam and several comparison broad-spectrum compounds was assessed against recent clinical isolates of Gram-positive and -negative bacteria from geographically diverse medical centers in Europe, North and Latin America participating in various surveillance programs in 2000. Several organisms were characterized for phenotypic expression of various resistant determinants such as extended-spectrum beta-lactamase (ESBL) or amp C cephalosporinase hyperproduction, and vancomycin resistance in enterococci (VRE). Piperacillin/tazobactam retained activity (MIC50) against oxacillin-susceptible Staphylococcus spp. (0.12-0.5 microg/ml), Bacillus spp. (0.5 microg/ml), vancomycin-susceptible enterococci (>4 microg/ml), and Corynebacterium spp. (2 microg/ml; not including C. jeikeium) with susceptibility rates of 100.0, 91.7, 85.7 and 81.8%, respectively. Piperacillin/tazobactam inhibited all Streptococcus spp. strains at < or = 16 microg/ml, including penicillin-resistant strains many of which were co-resistant to erythromycin (90%) and other beta-lactams. A specific breakpoint for these streptococci when testing piperacillin/tazobactam appears needed to prevent false-resistant reports using penicillin as a class representative. The carbapenems among beta-lactams were the most active agents against the ESBL-producing species of Escherichia coli and Klebsiella pneumoniae and those strains which hyper-express amp C enzymes including Citrobacter spp. and Enterobacter spp. Piperacillin/tazobactam only exhibited modest activity against the "amp C resistance group" strains (68.8% susceptible or intermediate, MIC < or = 64 microg/ml). Piperacillin/tazobactam (MIC50, 8 microg/ml; 79.5% susceptible) was the most active agent tested against multi-drug resistant isolates of Pseudomonas aeruginosa. Against sampled Haemophilus influenzae (39.2% ampicillin-resistant), piperacillin/tazobactam (MIC(90,) < or = 0.06 microg/ml), ceftriaxone and ceftazidime inhibited 100.0% of the isolates at < or = 0.25 microg/ml. These in vitro surveillance results from the year 2000 on three continents, demonstrated a sustained potent activity of piperacillin/tazobactam against selected problematic nosocomial and community-acquired pathogens. The potential importance of these findings is that this beta-lactamase inhibitor combination can be used an empiric treatment of serious infections in hospital environments where resistance has emerged, as well as covering nearly all isolates of fastidious respiratory tract pathogens acquired in the community setting.
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PMID:Potency and antimicrobial spectrum update for piperacillin/tazobactam (2000): emphasis on its activity against resistant organism populations and generally untested species causing community-acquired respiratory tract infections. 1205 29

Clinical microbiology laboratories in Japan have not yet established standards for selecting the most appropriate antimicrobial agents for testing and reporting antimicrobial susceptibility that are comparable to the performance standards of the National Committee for Clinical Laboratory Standards(NCCLS) in the United States of America. Selection of the most appropriate antimicrobial agents for testing and reporting was discussed by a working group(WG) consisting of medical physicians, surgeons, pharmacists, medical technologists and medical microbiologists. The WG agreed on the following basic criteria for the selection of antimicrobial agents: 1) the agent should be useful when screening various resistant bacteria, 2) the agent should serve as a useful guide for physicians and residents when selecting antimicrobial agents, and 3) the agent should be useful for controlling nosocomial infections and resistant bacteria. Clinically isolated microorganisms were classified into 7 groups based on susceptibility to antimicrobial agents. These groups were Staphylococcus spp. or Enterococcus spp., Streptococcus spp. or Haemophilus spp., enterobacteriae, glucose non-fermenting gram positive rods(NFRs), anaerobic bacteria, fungi and mycobacterium. After considering clinical and bacteriological evidence, the WG decided on several antimicrobial agents for testing in clinical microbiology laboratories in Jichi Medical School Hospital. For the NFR group, these were Piperacillin(PIPC), ceftazidime(CAZ), cefepime, imipenem, amikacin and levofloxacin(LVFX). For the enterobacteriae group, these were Amplicillin(ABPC), PIPC, aztreonam, CAZ and LVFX. For the Staphylococcus spp. or Enterococcus spp. group, these were oxacillin, ABPC, vancomycin and gentamicin. We concluded that the most appropriate antimicrobial agent for testing and reporting must be economical and agreed upon at the hospital level, although the ultimate selection must be based on the available clinical and bacteriological evidence.
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PMID:[Selection of appropriate antimicrobial agents to test and report by clinical microbiology laboratories]. 1245 81

The in vitro activity of ertapenem against bacterial pathogens isolated from patients with moderate to severe complicated intra-abdominal, complicated skin/skin structure, acute pelvic, or complicated urinary tract infection or community acquired pneumonia was compared to ceftriaxone and piperacillin-tazobactam and related to known plasma concentrations of the three agents. Ertapenem was more potent against methicillin-susceptible Staphylococcus aureus (MSSA) than ceftriaxone and piperacillin-tazobactam and was more potent and more active than both of these agents against Enterobacteriaceae and anaerobes. Piperacillin-tazobactam was the most active agent against enterococci and Pseudomonas aeruginosa. All isolates of Enterobacteriaceae (n=1088), Streptococcus pyogenes (n=37), Streptococcus agalactiae (n=48), MSSA (n=187), Haemophilus influenzae (n=59), and Moraxella catarrhalis (n=9) were susceptible to ertapenem; < 1% of 1284 anaerobes and only 1 of 113 Streptococcus pneumoniae (a penicillin-resistant isolate) were resistant to ertapenem. The MIC value at which 90% of all Enterobacteriaceae, streptococci, MSSA, H. influenzae, M. catarrhalis, and anaerobes were inhibited (MIC90) was < or = 1 microg/ml and below the mean plasma concentration of total ertapenem following a 1 g intravenous infusion for at least 24 hours, i.e., the entire recommended dosing interval, and below the free drug concentration for at least 8 h.
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PMID:In vitro activity of ertapenem against common clinical isolates in relation to human pharmacokinetics. 1246 28

A study was conducted in 1999 on the activity of piperacillin-tazobactam on 1349 strains collected in a Spanish multicenter study involving 10 hospitals. A total of 897 Gram-negative bacteria of the following genuses were collected: Escherichia coli (169), Klebsiella spp. (112), Pseudomonas spp. (122), Enterobacter spp. (92), Serratia spp. (44), Citrobacter spp. (37), Proteus spp. (114), Morganella spp. (49), Acinetobacter spp. (47), Stenotrophomonas spp. (47), Haemophilus spp. (45), Moraxella spp. (19). The Gram-positive bacteria included Staphylococcus aureus (116), Streptococcus pneumoniae (92), and Enterococcus spp. (114). Piperacillin-tazobactam activity against different anaerobic bacteria was also determined: Bacteroides spp. (88), Clostridium spp. (25), Prevotella spp. (5), Fusobacterium spp. (3) and Peptosteptococcus spp. (9). The piperacillin-tazobactam combination was found to maintain its activity against the isolated microorganisms with regard to the previous study.
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PMID:[Second multicenter study of the in vitro susceptibility to piperacillin-tazobactam]. 1258 46

The in vitro activity of piperacillin-tazobactam and several antibacterial drugs commonly used in Argentinean hospitals for the treatment of severe infections was determined against selected but consecutively isolated strains from clinical specimens recovered from hospitalized patients at 17 different hospitals from 9 Argentinean cities from different geographic areas during the period November 2001-March 2002. Out of 418 Enterobacteriaceae included in the Study 84% were susceptible to piperacillin-tazobactam. ESBLs putative producers were isolated at an extremely high rate since among those isolates obtained from patients with hospital acquired infections 56% of Klebsiella pneumoniae, 32% of Proteus mirabilis and 25% Escherichia coli were phenotypically considered as ESBLs producers Notably P.mirabilis is not considered by for screening for ESBL producers. ESBLs producers were 100% susceptible to imipenem and 70% were susceptible to piperacillin-tazobactam whereas more than 50% were resistant to levofloxacin. The isolates considered as amp C beta lactamase putative producers showed 99% susceptibility to carbapenems while 26.7% were resistant to piperacillin-tazobactam and 38.4% to levofloxacin. Noteworthy only 4% of the Enterobacteriaceae isolates were resistant to amikacin. Piperacillin-tazobactam was the most active agent against Pseudomonas aeruginosa isolates (MIC(90): 128 microg/ml; 78% susceptibility) but showed poor activity against Acinetobacter spp (MIC(90):>256 microg/ml; 21.7% susceptibility). Only 41.7% Acinetobacter spp isolates were susceptible to ampicillin-sulbactam. Piperacillin-tazobactam inhibited 100% of Haemophilus influenzae isolates (MIC(90) < 0.25 microg/ml) but only 16.6% of them were ampicillin resistant. The activity of piperacillin-tazobactam against oxacillin susceptible Staphylococcus aureus or coagulase negative staphylococci was excellent (MIC(90) 2 microg/ml; 100% susceptibility). Out of 150 enterococci 12 isolates (8%) were identified as E.faecium and only three isolates (2%), 2 E.faecium and 1 E.faecalis were vancomycin resistant. All the enterococci isolates were susceptible to linezolid. Piperacillin-tazobactam showed excellent activity (MIC(90) 2 microg/ml; 92% susceptibility). Regarding pneumococci all the isolates showed MICs of 16 microg/ml for piperacillin-tazobactam. Among 34 viridans group streptococci only 67% were penicillin susceptible and 85.2% ceftriaxone susceptible whereas piperacillin-tazobactam was very active (MIC(90) 4 microg/ml).Piperacillin-tazobactam is therefore a very interesting antibacterial drug to be used, preferably in combination (IE: amikacin-vancomycin) for the empiric treatment of severe infections occurring in hospitalized patients in Argentina. Caution must be taken for infections due to ESBL producers considering that the inoculum effect MICs can affect MIC values.
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PMID:Argentinean collaborative multicenter study on the in vitro comparative activity of piperacillin-tazobactam against selected bacterial isolates recovered from hospitalized patients. 1459 72

We aimed to prospectively evaluate the clinical and bacteriological effects of piperacillin in children with pneumonia. Twenty-eight patients (6 months to 5 years of age) with pneumonia were treated with piperacillin. In the same period, 95 strains of Haemophilus influenzae and 41 strains of Streptococcus pneumoniae were isolated in our department and the minimum inhibitory concentration (MIC) of piperacillin was determined. The clinical efficacy of piperacillin was excellent in 4 cases, good in 23, and fair in 1; the response rate was 96.4% (27/28). Among the isolates from our department, there were 4 strains (9.8%) of penicillin-susceptible S. pneumoniae (PSSP), 32 strains (78.0%) of penicillin-intermediate-resistant S. pneumoniae (PISP), and 5 strains (12.2%) of penicillin-resistant S. pneumoniae (PRSP). Against S. pneumoniae, the MIC50 and MIC90 for piperacillin were 0.5 microg/ml and 2 microg/ml, respectively. Panipenem showed the best results, followed by piperacillin, ampicillin, and flomoxef. Among the isolates from our department, there were 51 strains (53.7%) of beta-lactamase-negative ampicillin-susceptible H. influenzae, 42 strains (44.2%) of beta-lactamase-negative ampicillin-resistant H. influenzae, 1 strain (1.1%) of beta-lactamase-positive ampicillin-resistant H. influenzae, and 1 strain (1.1%) of beta-lactamase-positive amoxicillin-clavulanic acid-resistant H. influenzae. The MIC50 and MIC90 for piperacillin against H. influenzae were 0.0625 microg/ml and 0.125 microg/ml, respectively. Tazobactam/piperacillin and piperacillin showed the best results, followed by panipenem, ampicillin, and flomoxef. Piperacillin proved to be very useful for the treatment of pneumonia in children.
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PMID:Clinical and bacteriological evaluation of the efficacy of piperacillin in children with pneumonia. 1772 85


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