Susceptibility of Bacterial Isolates From Turkey - A Report From the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program

Abstract

The study monitored the susceptibility of nosocomial pathogens to meropenem and comparator antimicrobial agents isolated as part of the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program from Turkish university hospitals. In terms of minimum inhibitory concentration 90% (MIC₉₀) values, meropenem was two- and eight-fold more active than imipenem against Escherichia coli and Klebsiella pneumoniae, respectively. 40.5% of K. pneumoniae, 23.1% of Klebsiella oxytoca and 15.3% of E. coli isolates were extended-spectrum β-lactamase (ESBL) producers. Piperacillin/tazobactam was the most active agent against isolates of Pseudomonas aeruginosa, followed by meropenem and imipenem. Against Acinetobacter baumannii isolates, meropenem and imipenem were the most active agents. Continued surveillance by the MYSTIC Program appears to be prudent to help focus on effective empiric treatment regimens.     

Antimicrobial resistance in gram-negative isolates from European intensive care units: data from the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) programme

Susceptibility data were collected for 6243 gram-negative isolates from 29 European ICUs participating in the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Programme (1997-2000). The most commonly isolated bacteria were Pseudomonas aeruginosa (22.5%), Escherichia coli (19.8%), Klebsiella pneumoniae (10.4%), and Enterobacter cloacae (7.7%). The incidence of extended-spectrum beta-lactamase-producers was higher in Turkish, Russian and Italian ICUs (27.9-39.6%) than in other countries (2.5-10.8%). The frequency of AmpC-cephalosporin hyper-producers was 16.8-55.4%. Meropenem was more active against Proteus mirabilis than imipenem (99.0% versus 88.8% susceptibility, respectively). Against Acinetobacter baumannii, meropenem (79.6% susceptible) and imipenem (82.2%) were more active than comparators (34.3-51.6%). Meropenem and imipenem exhibited good activity against P. aeruginosa (76.1% and 68.2%, respectively; but with inter-country variation). Ciprofloxacin resistance in E. coli and K. pneumoniae increased and needs close monitoring. Meropenem (98.2-99.8% susceptibility) and imipenem (88.8-99.4%) remained potent against important species of gram-negative bacteria from European ICUs actively using meropenem.     

Comparative antimicrobial potency of meropenem tested against Gram-negative bacilli: report from the MYSTIC surveillance program in the United States (2004)

The Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program is a longitudinal resistance surveillance network of more than 100 medical centers worldwide monitoring the susceptibility of bacterial pathogens to carbapenems and other broad-spectrum agents. In 2004 (year six), the antimicrobial activity of 12 broad-spectrum agents was assessed against 2,799 Gram-negative bacterial isolates submitted from 15 United States (USA) medical centers using Clinical and Laboratory Standards Institute (CLSI; formerly NCCLS) recommended methods. Meropenem continued to demonstrate a high potency with MIC90 values 4- to 32-fold lower than imipenem against the Enterobacteriaceae. The wide spectrum of activity for meropenem against all Gram-negative isolates was demonstrated by the overall rank order of percentage susceptibility at CLSI breakpoints: amikacin (96.5%) > meropenem (96.0%) > imipenem (95.8%) > piperacillin/tazobactam (91.5%) > tobramycin (91.4%) > cefepime (91.2%) > ceftazidime (89.0%) > gentamicin (88.0%) > aztreonam (81.5%) > levofloxacin (80.5%) > ciprofloxacin (80.2%) > ceftriaxone (69.1%). Only the aminoglycosides (84.5%) and carbapenems (76.1-83.8%) exhibited acceptable levels of susceptibility against the Acinetobacter spp. isolates as this species group became more resistant to all antimicrobial classes. A continued increase in the resistance rate for both ciprofloxacin and levofloxacin over the six years was observed, most alarming among Escherichia coli (20.2-20.7%) and indole-positive Proteus species (34.4-42.2%) isolates, some documented as clonal. Continued surveillance of these broad-spectrum antimicrobial agents appears warranted to monitor the potency and spectrum of activity against Gram-negative pathogens causing serious infections and the emergence of new or novel resistance mechanisms that could compromise carbapenem therapy.     

Resistance surveillance in Italy: four-year results from the MYSTIC program

The MYSTIC program is an international, multicenter surveillance study that compares the activity of meropenem, in centers that are prescribers, with that of imipenem, ceftazidime, piperacillin/tazobactam, ciprofloxacin and gentamicin. These Italian data are from 3 centers (neutropenia, cystic fibrosis and intensive care units). A total of 2,072 (238 Gram-positive and 1,834 Gram-negative) aerobic microorganisms were collected during the study. Pseudomonas aeruginosa (33.4%) was the most isolated species followed by Escherichia coli (14.4%). All except one Enterobacteriaceae strain isolated were fully susceptible to meropenem. Moreover, the activity of meropenem against Enterobacteriaceae was about eight-fold greater than that of imipenem and four- to eight-fold more active than that of ceftazidime. Meropenem was highly active against non-fermentative Gram-negative microorganisms, exceeding the activity of most of the other antimicrobial agents tested. Moreover, meropenem showed increasing activity during the 4 years of study (starting from 86.2% in 1997 to 94.0% in 2000). In conclusion, our results indicate that meropenem has excellent potency and spectrum of activity despite being prescribed for the treatment of seriously ill patients, and appears to be a reliable option for the initial empirical treatment of serious nosocomial infections.     

Resistance Surveillance in Italy: Four-Year Results from the MYSTIC Program

Abstract

The MYSTIC program is an international, multicenter surveillance study that compares the activity of meropenem, in centers that are prescribers, with that of imipenem, ceftazidime, piperacillin/tazobactam, ciprofloxacin and gentamicin. These Italian data are from 3 centers (neutropenia, cystic fibrosis and intensive care units). A total of 2,072 (238 Gram-positive and 1,834 Gramnegative) aerobic microorganisms were collected during the study. Pseudomonas aeruginosa (33.4%) was the most isolated species followed by Escherichia coli (14.4%). All except one Enterobacteriaceae strain isolated were fully susceptible to meropenem. Moreover, the activity of meropenem against Enterobacteriaceae was about eight-fold greater than that of imipenem and four- to eight-fold more active than that of ceftazidime. Meropenem was highly active against non-fermentative Gram-negative microorganisms, exceeding the activity of most of the other antimicrobial agents tested. Moreover, meropenem showed increasing activity during the 4 years of study (starting from 86.2% in 1997 to 94.0% in 2000). In conclusion, our results indicate that meropenem has excellent potency and spectrum of activity despite being prescribed for the treatment of seriously ill patients, and appears to be a reliable option for the initial empirical treatment of serious nosocomial infections.     

Emerging antimicrobial resistances among Proteus mirabilis in Europe: report from the MYSTIC Program (1997-2001). Meropenem Yearly Susceptibility Test Information Collection

Resistance patterns that are currently problematic in Europe can vary greatly within the same species over time, among various patient populations and among geographic regions on the same continent. The results from the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program, which monitors carbapenem resistance rates in institutions using meropenem, were used to determine resistance differences among Proteus mirabilis. MIC results from 688 P. mirabilis strains were classified into 4 patient care groups: ICU (n=426), neutropenia patients (NP; n=145), general wards (n=97) and cystic fibrosis patients (CF; n=20). A total of 40 centers from 12 European countries have participated since 1997, divided into 3 geographic regions (East, North, South). All testing was performed by NCCLS reference methods and interpretive criteria, including screening of extended-spectrum beta-lactamase (ESBL) phenotypes. Over the monitored interval the resistance rates varied for each agent without a clear trend toward a greater rate. Rank order of susceptibility was: meropenem (99%) > piperacillin/tazobactam (TAZ; 96%) > cefepime (95%) > ceftazidime (CAZ; 94%) > imipenem (IPM; 92%). Ciprofloxacin (CIP) was the least active agent tested (MIC90 4 microg/ml; 86% susceptible). Unexpectedly, 3.6% of P. mirabilis were imipenem-resistant (MIC, > or = 16 microg/ml). Greater rates of resistance were found for strains from NP and CF patients, and from eastern or southern European sites, usually associated with epidemic clusters. Generally susceptible species such as P. mirabilis have recently emerged as therapeutic problems in European medical centers following mutations that compromise CIP, CAZ and aminoglycoside use. Imipenem also showed decreased susceptibility of greater than 7% compared to less than 1% for meropenem. Continued surveillance by the MYSTIC Program appears to be a prudent practice to focus effective empiric treatment regimens.     

Susceptibility of 497 clinical isolates of gram-negative anaerobes to trovafloxacin and eight other antibiotics

Trovafloxacin is a novel investigational trifluoronaphthyridone antibiotic with broad-spectrum activity against Gram-positive and Gram-negative organisms. Its in-vitro activity and those of eight other antimicrobial agents were evaluated against 497 clinical isolates of Gram-negative anaerobic bacteria by the agar dilution method. Trovafloxacin had excellent activity, with a minimum inhibitory concentration (MIC) range of <0.03-4 microg/ml, against all species. Out of the 497 isolates tested, 496 (99.5%) were inhibited by a concentration of < or = 2.0 microg/ml of trovafloxacin; the remaining two strains were inhibited by a concentration of 4.0 microg/ml. The MIC50s and MIC90s were 0.12 microg/ml and 1.0 microg/ml, respectively. Meropenem, imipenem and piperacillin/tazobactam were also very active. Overall, at the MIC90s, trovafloxacin was as active as meropenem, slightly more active than metronidazole and imipenem, twice as active as amoxicillin-clavulanic acid, five times more active than piperacillintazobactam and 68 times more active than clindamycin. About 21% of the isolates were resistant to cefoxitin, 30% to clindamycin and 40% to piperacillin. Five species in the Bacteroides fragilis group of isolates were highly resistant to metronidazole (MIC >128 microg/ml). In general, the relatively more resistant species were the B. vulgatus, B. ovatus, B. thetaiotaomicron, and B. fragilis sensu stricto, in that order. All the isolates of the B. fragilis group and about 50% of the Prevotella spp. were beta-lactamase positive. Trovafloxacin certainly holds promise as an alternative drug for therapy of anaerobic infections.     

In Vitro Activity of Meropenem against Ciprofloxacin-Resistant Enterobacteriaceae and Pseudomonas aeruginosa

Abstract

The in-vitro susceptibilities of a total of 174 ciprofloxacin-resistant Enterobacteriaceae and Pseudomonas aeruginosa were determined. According to the BSAC and NCCLS breakpoints, meropenem, aztreonam, ceftibuten, ceftazidime, imipenem and cefotaxime were the most active (>90%) antimicrobial agents tested against Enterobacteriaceae. Susceptibility of these strains to piperacillin/tazobactam, cefpodoxime and cefixime (84.96%) was higher than that to tobramycin, gentamicin and fosfomycin (50-75%). More than 90% of P. aeruginosa were susceptible to meropenem when both interpretative susceptibility breakpoint criteria were used. Piperacillin, piperacillin/tazobactam and ceftazidime were active against 50-75% of the same strains. Meropenem was the most active antimicrobial tested against all ciprofloxacin-resistant clinical isolates assayed.     

Monitoring of antibiotic resistance in bacterial isolates from bacteremic patients

The aim of the study was to monitor the prevalence of pathogens and development of resistance in bacteria isolated from bacteremic patients. Five University Clinics and/or Regional Hospitals in the Slovak Republic participated in the study and a total of 421 isolates were collected in the second half of the year 2002. The most prevalent organisms were coagulase-negative staphylococci (CONS) (19%), Staphylococcus aureus (18.3%), among Gram-negative bacteria Escherichia coli (13.3%), Klebsiella pneumoniae (11.4%) and Pseudomonas aeruginosa (7.8%) followed by enterococci, Acinetobacter baumannii and Enterobacter sp. All CONS and S. aureus were susceptible to vancomycin; resistance to oxacillin was observed for 55% of the CONS and only for 4% of S. aureus isolates. A higher prevalence of resistance to erythromycin, clindamycin, gentamicin and ofloxacin was found in CONS in comparison to S. aureus. Enterococcus sp. isolates were fully susceptible to vancomycin and teicoplanin. Gentamicin, amoxicillin/clavulanate, third generation cephalosporins and ciprofloxacin showed good activity against E. coli. Although 17% of K. pneumoniae isolates were resistant to ciprofloxacin, it was the most effective drug against K. pneumoniae; the prevalence of resistance to other antibiotics was rather higher. Gentamicin and ciprofloxacin were the most active against Enterobacter sp. isolates and ceftazidime and meropenem against P. aeruginosa.     

In-vitro activity of meropenem, a new carbapenem, against imipenem-resistant Pseudomonas aeruginosa and Xanthomonas maltophilia

The activity of meropenem, a new carbapenem, as well as imipenem, ceftazidime, aztreonam, tobramycin, amikacin and ciprofloxacin against 18 strains of Xanthomonas maltophilia and 23 strains of Pseudomonas aeruginosa resistant to imipenem was tested. All strains of X. maltophilia were resistant to both penems. Ceftazidime, tobramycin and ciprofloxacin were the most active antimicrobial agents against this specie. 17% of imipenem-resistant strains of P. aeruginosa were sensitive to meropenem. Ciprofloxacin, amikacin and aztreonam were the most effective agents against these strains.     

Emerging Antimicrobial Resistances Among Proteus mirabilis in Europe: Report from the MYSTIC Program (1997-2001)

Abstract

Resistance patterns that are currently problematic in Europe can vary greatly within the same species over time, among various patient populations and among geographic regions on the same continent. The results from the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program, which monitors carbapenem resistance rates in institutions using meropenem, were used to determine resistance differences among Proteus mirabilis. MIC results from 688 P. mirabilis strains were classified into 4 patient care groups: ICU (n=426), neutropenia patients (NP; n=145), general wards (n=97) and cystic fibrosis patients (CF; n=20). A total of 40 centers from 12 European countries have participated since 1997, divided into 3 geographic regions (East, North, South). All testing was performed by NCCLS reference methods and interpretive criteria, including screening of extended-spectrum β-lactamase (ESBL) phenotypes. Over the monitored interval the resistance rates varied for each agent without a clear trend toward a greater rate. Rank order of susceptibility was: meropenem (99%) > piperacillin/tazobactam (TAZ; 96%) > cefepime (95%) > ceftazidime (CAZ; 94%) > imipenem (IPM; 92%). Ciprofloxacin (CIP) was the least active agent tested (MIC₉₀, 4 μg/ml; 86% susceptible). Unexpectedly, 3.6% of P. mirabilis were imipenem-resistant (MIC, >16 μg/ml). Greater rates of resistance were found for strains from NP and CF patients, and from eastern or southern European sites, usually associated with epidemic clusters. Generally susceptible species such as P. mirabilis have recently emerged as therapeutic problems in European medical centers following mutations that compromise CIP, CAZ and aminoglycoside use. Imipenem also showed decreased susceptibility of greater than 7% compared to less than 1% for meropenem. Continued surveillance by the MYSTIC Program appears to be a prudent practice to focus effective empiric treatment regimens.     

Resistance patterns of Pseudomonas aeruginosa to carbapenems and piperacillin/tazobactam.

Pseudomonas aeruginosa is a major problem as a multiresistant nosocomial pathogen, especially in burns and other immunocompromised patients in our hospital. The present prospective study, conducted between June 1996 and December 1997, was aimed at determining the extent of its resistance against highly active antipseudomonal drugs, such as carbapenems (imipenem and meropenem) and ureidopenicillin with beta-lactamase inhibitor (piperacillin/tazobactam); existence of any cross resistance or difference in susceptibility between imipenem and meropenem; and to compare the activity of piperacillin/tazobactam with the two carbapenems against P. aeruginosa. Of the 357 P. aeruginosa isolates tested from 188 patients 37 (10.4%) were resistant to imipenem, 21 (5.9%) to meropenem and 50 (14%) to piperacillin/tazobactam. Cross resistance between the two carbapenems was observed in 5.9% of the isolates. Sixteen (43%) of the imipenem-resistant isolates were susceptible to meropenem but the reverse was observed in none. Amongst the 50 piperacillin/tazobactam-resistant isolates cross resistance with the two carbapenems was observed in 18 (36%) and in 9 (18%) only with imipenem; 23 (46%) were susceptible to both. Our results indicate that P. aeruginosa is least resistant to meropenem followed by imipenem and piperacillin/tazobactam. Cross resistance between the carbapenems and between carbapenems and piperacillin/tazobactam was found. The study further suggests that burns, cardiac-neuro-pediatric surgical, cancer and transplant patients are more susceptible to acquiring infection due to multiresistant P. aeruginosa than other types of patients and common infection sites were wounds, respiratory tract, urine, blood and intravascular lines.     

Comparative in vitro activity of sparfloxacin (AT 4140, RP 64206--SPFX) against 275 multiresistant clinical isolates.

The in-vitro activity of sparfloxacin was compared with that of pefloxacin, ofloxacin, ciprofloxacin, imipenem, ceftazidime, gentamicin and amikacin against 275 multiresistant nosocomial clinical isolates. They consisted of Pseudomonas aeruginosa (37), Enterobacter cloacae (42), Acinetobacter anitratus (60), Klebsiella pneumoniae (37) and Staphylococcus sp (99). Minimum inhibitory concentrations (MIC90) and geometric mean MICs for sparfloxacin were as follows (mg/l): P. aeruginosa 128-23.7, E. cloacae 1-0.13, A. anitratus 2-0.14, K. pneumoniae 1-0.08, MRSA 16-0.98, MSSA 0.12-0.03, MRSE 0.25-0.12 and MSSE 0.12-0.05. It is concluded that sparfloxacin was the most potent agent against staphylococci and A. anitratus including strains resistant to the other quinolones while ciprofloxacin was the most potent agent against P. aeruginosa, E. cloacae and K. pneumoniae.     

In- Vitro Activity of Meropenem,a New Carbapenem,Against Imipenem-Resistant Pseudomonas aeruginosa and Xanthomonas maltophilia

Summary

The activity of meropenem, a new carbapenem, as well as imipenem, ceftazidime, aztreonam, tobramycin, amikacin and ciprofloxacin against 18 strains of Xanthomonas maltophilia and 23 strains of Pseudotnonas aeruginosa resistant to imipenem was tested. All strains of X. maltophilia were resistant to both penems. Ceftazidime, tobramycin and ciprofloxacin were the most active antimicrobial agents against this specie. 17% of imipenem-resistant strains of P. aeruginosa were sensitive to meropenem. Ciprofloxacin, amikacin and aztreonam were the most effective agents against these strains.     

Bacterial isolates from severe infections and their antibiotic susceptibility patterns in Italy: a nationwide study in the hospital setting

The most frequent agents of severe bacterial infections and their antibiotic susceptibility patterns were determined in patients admitted to 45 Italian hospitals over the years 2002-2003. The most common diagnoses were: sepsis (33.8%), pneumonia (9.4%), intravascular catheter-associated infections (9.3%) and ventilator-associated pneumonia (8.1%). Overall, 5115 bacterial isolates were identified from 4228 patients. Three bacterial species, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, accounted for more than 50% of the isolates. Other prevalent bacterial isolates were Staphylococcus epidermidis and Enterococcus faecalis, while Acinetobacter baumanii ranked third among all Intensive Care Unit (ICU) isolates. 7% of S. aureus had intermediate resistance to vancomycin. Although E. faecalis displayed no vancomycin resistance, 34% of vancomycin-resistant isolates were found among Enterococcus faecium, one of the highest rates found to date, emphasizing the difference between these two enterococcal species. All the Gram-positive pathogens were susceptible to linezolid, with the exception of approximately 2% of the enterococcal isolates that were intermediate with a minimum inhibitory concentration (MIC)=4 microg/ml. Almost 10% of Escherichia coli, 14% of Klebsiella pneumoniae, 22% of Serratia marcescens and 50% of Enterobacter cloacae were non-susceptible to cefotaxime. Amikacin was the most active antibiotic against P. aeruginosa that showed lack of susceptibility to ceftazidime, gentamicin, piperacillin and ciprofloxacin ranging from 20 to 35%. Finally, Acinetobacter baumanii showed a high level of resistance to all the antibiotics tested including imipenem (58%). The results obtained in this study, the first of its kind in Italy, offer indications for guiding empirical therapy and implementing specific interventions to fight antibiotic-resistant bacterial infections and their transmission in the hospital setting in Italy.     

In-vitro activities of imipenem–colistin,imipenem–tigecycline,and tigecycline–colistin combinations against carbapenem-resistant Enterobacteriaceae*

The aim of the study is to determine in-vitro effects of imipenem–tigecycline, imipenem–colistin and tigecycline–colistin against carbapenem-resistant Enterobacteriaceae (CRE) isolates. A total of 25 CRE isolates were included to the study. The minimum inhibition concentrations of imipenem, colistin-sulphate and tigecycline were determined with broth dilution method. Synergistic effects of imipenem–tigecycline, imipenem–colistin and tigecycline–colistin were investigated by microdilution checkerboard technique. All of the isolates were resistant to imipenem, whereas 25% of the isolates were resistant to colistin and tigecycline. Imipenem–colistin, imipenem–tigecycline and tigecycline–colistin combinations were synergistic against 40% (10/25), 24% (6/25), and 36% (9/25) of the isolates, respectively. Antagonism was observed in 8% (2/25) of the isolates in tigecycline–colistin combination. Tigecycline–colistin was the most effective (70% synergy) combination in Klebsiella spp. strains; whereas imipenem–colistin was the most effective (75% synergy) combination in Escherichia coli strains. Synergistic effect was variable and strain-depended against CRE isolates that have been tested.     

Susceptibility of 228 Non-fermenting Gram-Negative Rods to Tigecycline and Six Other Antimicrobial Drugs

Abstract

The aim of the study was to determine the in vitro activity of tigecycline and 6 other antimicrobial drugs used in clinical practice against 228 clinical isolates of nonfermenting Gram-negative rods (NFGNRs) including Acinetobacter spp. Stenotrophomonas maltophilia, and Pseudomonas aeruginosa. Minimum inhibitory concentrations (MICs) were determined according to the recommendations of the Clinical and laboratory Standards institute. For tigecycline, we used the criteria approved by the FDA. Almost 50% of the clinical isolates of Acinetobacter spp. were resistant to piperacillin/tazobactam, ciprofloxacin, gentamicin, and ceftazidime. Strains of this microorganism were more susceptible to imipenem, and even more susceptible to colistin and tigecycline; no strains were resistant to tigecycline. Stenotrophomonas maltophilia showed even greater resistance to the drugs tested. Thus, all strains were resistant to imipenem and a large percentage (82.6%) were resistant to piperacillin/tazobactam. Resistance to the other agents tested was also high, with the exception of tigecycline, with only 3 resistant strains (MIC <8 mg/ml). Tigecycline, on the other hand, was scarcely active against Pseudomonas aeruginosa, which bears efflux pump systems such as MexXY-OprM. Almost 90% of strains were resistant to ciprofloxacin; only 8% were resistant to gentamicin; over half were colistin-intermediate or -resistant, and finally, approximately half of the strains were susceptible to the 3 beta-lactams studied. In conclusion, NFGNRs present variable susceptibility patterns, although they are generally highly resistant to antimicrobial agents including those considered more specific. Tigecycline, which showed good activity against most of the strains examined, broadens the spectrum of drugs available for the treatment of infections caused by these complex microorganisms.     

Surveillance of antimicrobial resistance in gram-negative isolates from intensive care units in Turkey: analysis of data from the last 5 years

A multicenter antimicrobial surveillance program was established in Turkey in 1995 to monitor the predominant Gram-negative pathogens from intensive care units (ICUs) and antimicrobial resistance patterns of these isolates. Sixteen hospitals participated in the study and a total of 1479 isolates from 1,100 patients were collected. The isolates were tested for their susceptibility against 13 antibiotics by E-test method. Minimum inhibitory concentrations (MICs) for each isolate were determined for imipenem, ceftazidime, ceftazidime-clavulanate, cefoperazone-sulbactam, ceftriaxone, cefepime, cefuroxime, piperacillin-tazobactam, ticarcillin-clavulanate, gentamicin, amikacin and ciprofloxacin. The most common isolates were Pseudomonas spp. (28.2%), Escherichia coli (19.2%) and Klebsiella spp. (19.1%). We found very high resistance rates to all major antibiotics that are used to treat serious infections. Although imipenem is the most active agent, it had an overall susceptibility rate of 68%. Half of the tested Klebsiella spp. strains were found to produce ESBL. This is a very high rate when compared with the literature. Cross-resistance among species was also investigated. 52% of ciprofloxacin-resistant strains were also resistant to imipenem, 80% to ceftazidime, 97% to ceftriaxone, 86% to amikacin and 19% of imipenem-resistant strains were susceptible to ceftazidime and 18% to amikacin. When susceptibilities of the years 1995 and 1999 were compared, the most interesting finding was the decrease in resistance to 3rd generation cephalosporins. In conclusion, this national clinical isolate database shows that resistance rates are high, the change over years is not predictable and continuous surveillance is necessary to monitor antimicrobial resistance and to guide antibacterial therapy.     

Antimicrobial susceptibility patterns of clinical isolates of gram-negative bacteria obtained from intensive care units in a tertiary hospital in Beijing, China

In this study we investigated the prevalence of antimicrobial resistance in clinical isolates of Gram-negative bacteria obtained from intensive care units (ICUs) in the People's Liberation Army (PLA) 309 Hospital located in beijing, China. between 2007 and 2010, a total of 1949 isolates of Gram-negative bacteria were collected and tested using an antibiotic susceptibility assay. A marked decrease was observed in the susceptibility of Acinetobacter baumannii to imipenem and amikacin as compared to that described in a previous report in China. Similar results were obtained for Pseudomonas aeruginosa. However, imipenem and amikacin showed strong activity against Escherichia coli and Klebsiella pneumoniae. Overall, the high rates of antimicrobial resistance against ICU pathogens in our hospital indicated a critical condition in Beijing, China. Development of a national control and monitoring system by the government may be an ideal method to solve the present problem of managing infections due to Gram-negative bacterial pathogens.     

In vitro activity of cefepime and cefotaxime compared to six other agents against 350 penicillin-susceptible and penicillin-resistant Streptococcus pneumoniae

From January 1996 to December 1997, we evaluated the in vitro activity of 8 antimicrobials (penicillin, amoxycillin, amoxycillin/clavulanate, cefuroxime, ceftazidime, cefepime, cefotaxime, and imipenem) against 350 Streptococcus pneumoniae clinical isolates collected from two hospitals. Imipenem, cefepime and cefotaxime were the most active antibiotics against penicillin-intermediate (PI) and highly penicillin-resistant (PR) S. pneumoniae with MICs 2- to 8-fold lower than penicillin. Against PI and PR pneumococci amoxycillin and amoxycillin/clavulanate were 2-times less active than cefepime and cefotaxime, while cefuroxime was 4-8-times less active. The majority of strains of serotypes 6B, 23F, 14, 9 and 19 were penicillin-resistant, both intermediate (68%) and highly resistant (32%).