Occurrence and antimicrobial susceptibility patterns of pathogens isolated from skin and soft tissue infections: report from the SENTRY Antimicrobial Surveillance Program (United States and Canada, 2000)

A total of 1,404 bacterial isolates were recovered from skin and soft tissue infections (SSTIs) from hospitalized patients in 24 sites in the United States (US) and 5 Canadian medical centers as part of the SENTRY Antimicrobial Surveillance Program. Isolates were collected between October and December, 2000. The rank order of pathogens was: Staphylococcus aureus (45.9%), Pseudomonas aeruginosa (10.8%), Enterococcus spp. (8.2%), Escherichia coli (7.0%), Enterobacter spp. (5.8%) and Klebsiella spp. (5.1%). The same order was observed in the US and Canada. Of note, almost 30% of S. aureus were oxacillin-resistant. Vancomycin resistance among enterococci was low (7.8%) representing a marked decrease from earlier SENTRY Program reports. Several antimicrobial agents remained very active against P. aeruginosa and Enterobacteriaceae isolates. In particular amikacin, cefepime, and the carbapenems (imipenem and meropenem) showed an excellent spectrum of activity (>95% susceptible). Extended-spectrum beta-lactamase production was observed in both E. coli (7.1%) and Klebsiella spp. (11.3%). Cefepime remained highly active, even against ceftazidime-resistant isolates of Enterobacter spp. The results of this study have identified the most common causes of SSTIs in hospitalized patients in North America, and can be used to make informed decisions concerning standards of empiric treatment for SSTIs in this region.     

Epidemiology and frequency of resistance among pathogens causing urinary tract infections in 1,510 hospitalized patients: a report from the SENTRY Antimicrobial Surveillance Program (North America)

Bacterial urinary tract infections (UTIs) are an important cause of septicemia resulting in high mortality rates, prolonged hospital stays and increased healthcare costs. Periodic reviews of pathogen frequency and susceptibility patterns impact on appropriate antimicrobial usage, leading to more effective prescribing practices. As part of the SENTRY Antimicrobial Surveillance Program (SENTRY, 1998), participants collected 50 consecutive UTI pathogens from patients hospitalized in 31 medical centers (26 in the United States and five in Canada) and forwarded subcultures to the coordinating center. Thirty-four antimicrobial agents were tested including two investigational compounds (quinupristin/dalfopristin [Q/D], gatifloxacin). The rank order of the 32 species identified during the study was: Escherichia coli (46.9%) > Enterococcus spp. (12.8%) > Klebsiella spp. (11.0%) > Pseudomonas aeruginosa (7.5%) > Proteus mirabilis (5.0%) > coagulase-negative staphylococci (CoNS; 3.4%). This pathogen rank order did not change from 1997 to 1998, but resistance patterns changed. Clonal spread of confirmed extended spectrum beta-lactamase-producing strains was not observed, but co-resistance was elevated for aminoglycosides, tetracyclines, sulfonamides, and fluoroquinolones. P. aeruginosa was most susceptible to amikacin (97.3%) > piperacillin +/- tazobactam (92.0-95.6%) > cefepime = imipenem (91.2%) > ceftazidime (85.8%). Fluoroquinolone resistance was greater in P. aeruginosa (24.8-39.8%) > P. mirabilis (5.3-13.3%) > Enterobacter spp. (6.7-8.9%) > Klebsiella spp. (4.2-7.8%) > E. coli (3.0-3.8%). Only 5% of enterococci were resistant to vancomycin. These results emphasize the need for continued surveillance studies for common infections which establish baseline resistance patterns by geographic areas, and have the potential to detect epidemics or direct local epidemiologic interventions.     

Evaluation of antimicrobial susceptibility for β-lactams against clinical isolates from 51 medical centers in Japan (2008)

This antimicrobial resistance surveillance study was performed in 51 medical centers in Japan over an 11-year period. The susceptibilities of 4228 strains including Escherichia coli (491 strains), Klebsiella spp. (462 strains), Enterobacter spp. (459 strains), Citrobacter freundii (358 strains), indole-positive Proteus spp. (386 strains), Serratia spp. (443 strains), Acinetobacter spp. (327 strains), Pseudomonas aeruginosa (473 strains), oxacillin-susceptible Staphylococcus aureus (481 strains), and coagulase-negative staphylococci (CoNS; 348 strains) were tested with 7 β-lactams (cefepime, cefpirome, ceftazidime, cefoperazone/sulbactam, imipenem, and piperacillin for gram-negative bacteria, or oxacillin for gram-positive bacteria). No resistance to these β-lactams (with the exception of ceftazidime) was found in oxacillin-susceptible S. aureus and CoNS. Of the E. coli clinical isolates, 24.6% were resistant to piperacillin, whereas 3.5% or less (cefpirome = 4.5%) were resistant to other β-lactam agents. Klebsiella spp. isolates were more susceptible to imipenem (99.6%), cefepime (98.7%), ceftazidime (98.5%), cefpirome (97.6%), and cefoperazone/sulbactam (97.6%). Isolates of Enterobacter spp., C. freundii, and Serratia spp. were susceptible to imipenem, cefepime, and cefpirome as well. The sensitivities of these organisms against cefepime and cefoperazone/sulbactam were 100%. Acinetobacter spp. isolates were less resistant to cefoperazone/sulbactam (0.6% resistance), imipenem (0.9%), and ceftazidime (2.8%) compared with other β-lactam antibiotics tested. Isolates of P. aeruginosa were more susceptible to piperacillin (9.1% resistance), cefoperazone/sulbactam (9.5%), and cefepime (6.6%) compared with ceftazidime (10.8%), cefpirome (16.3%), and imipenem (23.5%). The proportion of strains resistant to β-lactam antimicrobials has decreased compared with data from 2006 (Diagn. Microbiol. Infect. Dis. 60:177-183), reflecting the reduced consumption of β-lactams in Japan.     

Bacterial pathogens isolated from patients with skin and soft tissue infections: frequency of occurrence and antimicrobial susceptibility patterns from the SENTRY Antimicrobial Surveillance Program (United States and Canada, 1997). SENTRY Study Group (North America).

As part of the SENTRY Antimicrobial Surveillance Program, 1562 bacterial isolates were recovered from hospitalized patients with skin and soft tissue infections (SSTIs) in 30 United States (U.S.) and 8 Canadian medical centers between October and December, 1997. The overall rank order of recovery of the six most common pathogens was Staphylococcus aureus (42.6%) > Pseudomonas aeruginosa (11.3%) > Enterococcus spp. (8.1%) > Escherichia coli (7.2%) > Enterobacter spp. (5.2%) > beta-hemolytic streptocci (5.1%). With one exception, essentially the same order was observed in both the U.S. and Canada. The single exception was the Enterococcus group, which were the third most common isolate in the U.S. (9.6%), but the seventh most common isolate in Canada (3.7). Of note, 24.0% of S. aureus isolates were oxacillin resistant; vancomycin was uniformly active. Vancomycin resistance among Enterococcus spp. (16.5%) was observed only in the U.S. Several antimicrobial agents remained broadly active for SSTI isolates of P. aeruginosa, including meropenem, amikacin, tobramycin, and piperacillin with or without tazobactam. Imipenem resistance (MICs, > or = 8 micrograms/mL) was observed in 11.9% of isolates of P. aeruginosa and ceftazidime, and cefepime had equivalent activity (85.2% and 85.8% susceptible, respectively). Numerous beta-lactams, aminoglycosides and fluoroquinolones were broadly active against E. coli SSTI isolates (i.e. < 5% resistance). Extended-spectrum beta-lactamase production was uncommon both with E. coli and Klebsiella spp. in both nations. Cefepime, imipenem, and meropenem; the aminoglycosides; and fluoroquinolones were conspicuously more active against Enterobacter spp. than other agents tested. High-level, stably derepressed Amp C beta-lactamase production was commonly observed in this group (26.8%), but cefepime generally retained activity against these ceftazidime-resistant organisms. The results of this study serve to define the most common bacterial causes of SSTIs in North America, elucidate patterns of antimicrobial resistance and can be used as a basis for making initial empiric antimicrobial management decisions in hospitalized patients with such infections.     

In vitro evaluation of cefepime and other broad-spectrum beta-lactams in eight medical centers in Thailand. The Thailand Antimicrobial Resistance Study Group

The introduction of cephalosporins has had an important impact on the resistance rates to several clinically utilized beta-lactam antimicrobial agents. Most Thailand medical centers have not documented the levels of emerging resistant pathogens causing invasive infections. This study shows using reference-quality MIC techniques (Etest, AB BIODISK, Solna, Sweden), that carbapenem), "fourth-generation" cephalosporins (cefepime and cefpirome), and piperacillin/tazobactam were the most active agents tested against Gram-negative bacilli (Escherichia coli, Klebsiella spp., Enterobacter spp., Citrobacter spp., Serratia spp., indole-positive Proteae, Acinetobacter spp., Pseudomonas aeruginosa, and oxacillin-susceptible Staphylococcus spp. when compared to "third-generation" cephalosporins (ceftazidime and ceftriaxone). The rank order of activity for all species was imipenem (2.9% resistant) > cefepime (7.7%) > piperacillin/tazobactam (11.1%) > cefpirome (13.4%) > ceftriaxone (21.1%) > ceftazidime (29.9%). The incidence of extended spectrum beta-lactamase production among E. coli (15.7%) and K. pneumoniae (45.6%) was significant. Cefepime and imipenem were active against the majority of these isolates. The activity of cefepime was also shown to be very good against, 1) organisms capable of producing AmpC enzymes, 2) staphylococci species that were susceptible to oxacillin, and 3) many strains of nonfermentative Gram-negative bacilli. The prevalence of antimicrobial resistance in Thailand seems to be quite high among certain commonly encountered pathogens, and imipenem and cefepime have activity (susceptible and intermediate potency) against > 90% of these organisms.     

Evaluation of antimicrobial susceptibility for beta-lactams using the Etest method against clinical isolates from 100 medical centers in Japan (2006)

This antimicrobial resistance surveillance study was performed in 100 medical centers. Susceptibility testing (Etest; AB BIODISK, Solna, Sweden) of 9152 strains including Escherichia coli (991 strains), Klebsiella spp. (1000 strains), Enterobacter spp. (971 strains), Citrobacter spp. (803 strains), indole-positive Proteae spp. (834 strains), Serratia spp. (902 strains), Acinetobacter spp. (874 strains), Pseudomonas aeruginosa (992 strains), oxacillin-susceptible Staphylococcus aureus (984 strains), and coagulase-negative staphylococci (CoNS; 801 strains) was performed with 7 beta-lactams (cefepime, cefpirome, ceftazidime, cefoperazone/sulbactam, imipenem and piperacillin for Gram-negative bacteria, or oxacillin for Gram-positive bacteria). No strain resistance to these beta-lactams (except for ceftazidime) was found in oxacillin-susceptible S. aureus and CoNS. Of the E. coli clinical isolates, 17.1% were resistant to piperacillin, whereas 2.9% or less (cefpirome = 2.9%) were resistant to other beta-lactam agents. Klebsiella spp. strains were more susceptible to imipenem (99.9%), cefepime (99.2%), ceftazidime (98.6%), and cefpirome (98.3%). Isolates of Enterobacter spp., Citrobacter spp., indole-positive Proteae, and Serratia spp. were susceptible to imipenem, cefepime, and cefpirome as well. Acinetobacter spp. strains were least resistant to cefoperazone/sulbactam (0.7% resistance), imipenem (2.6%), cefepime (6.6%), and ceftazidime (7.7%) compared with other beta-lactam antibiotics tested. Isolates of P. aeruginosa were more susceptible to ceftazidime (8.7% resistance), cefoperazone/sulbactam (9.8%), and cefepime (8.9%) than piperacillin (11.9%), cefpirome (16.2%), and imipenem (12.4%). The percentage of imipenem-resistant P. aeruginosa was approximately 13% in clinical isolates in Japan. The proportion of strains resistant to beta-lactam antimicrobials has been decreasing compared with data from 2004, suggesting that reduced consumption of beta-lactams has reflected the decreased rates of resistant bacterial isolates in Japan.     

Evaluation of antimicrobial activity of beta-lactam antibiotics by Etest against clinical isolates from 100 medical centers in Japan (2004)

This antimicrobial resistance surveillance study was performed in 100 medical centers. The susceptibility of 9347 strains including Escherichia coli (997 strains), Klebsiella spp. (997 strains), Enterobacter spp. (988 strains), Citrobacter spp. (834 strains), indole-positive Proteae spp. (855 strains), Serratia spp. (925 strains), Acinetobacter spp. (902 strains), Pseudomonas aeruginosa (996 strains), oxacillin-susceptible Staphylococcus aureus (992 strains), and coagulase-negative staphylococci (861 strains) to 7 beta-lactam antibiotics, cefepime, cefpirome, ceftazidime, cefoperazone/sulbactam, imipenem and piperacillin (for gram negatives), or oxacillin (for gram positives) was tested. No strain resistant to these beta-lactams except for ceftazidime was found in oxacillin-susceptible S. aureus and coagulase-negative staphylococci. E. coli (16.5%) clinical isolates were resistant to piperacillin, whereas 1.5% or less (cefpirome = 1.5%) was resistant to other beta-lactams. Klebsiella spp. strains were more susceptible to imipenem (99.7%), cefepime (98.4%), and cefpirome (97.3%). Isolates of Enterobacter spp., Citrobacter spp., indole-positive Proteae, and Serratia spp. were susceptible to imipenem, cefepime, and cefpirome, as well. Acinetobacter spp. strains were most susceptible to cefoperazone/sulbactam (0.8% resistance), imipenem (3.2%), ceftazidime (6.0%), and cefepime (7.0%) than other beta-lactam antibiotics tested. Isolates of P. aeruginosa were more susceptible to ceftazidime (9.9% resistance), cefoperazone/sulbactam (14.9%), and cefepime (11.2%) than piperacillin (15.5%), cefpirome (19.1%), and imipenem (19.3%). The percentage of imipenem-resistant P. aeruginosa is around 20% in clinical isolates in Japan.     

Antimicrobial activity of cefepime tested against ceftazidime-resistant Gram-negative clinical strains from North American Hospitals: report from the SENTRY Antimicrobial Surveillance Program (1998-2004)

To assess the effect of ceftazidime resistance on the activity of other antimicrobial agents, 3030 ceftazidime-resistant Gram-negative bacilli (GNB) isolates (of a total of 42061 GNB) were tested against a panel of more than 30 agents. Ceftazidime resistance was observed in 40.3% of Acinetobacter spp., 16.9% of Pseudomonas aeruginosa, and 5.7% of Enterobacteriaceae isolates. The highest rates of ceftazidime resistance among the enteric GNB were observed with Enterobacter spp. (20.9%) >Citrobacter spp. (15.3%) > indole-positive Proteae (10.1%). Overall, 90% of ceftazidime-resistant Enterobacteriaceae and 30% of ceftazidime-resistant P. aeruginosa remained susceptible to the "4th-generation" cephalosporin, cefepime. The activities (% susceptible) of other antimicrobials tested against ceftazidime-resistant Enterobacteriaceae and P. aeruginosa, respectively, were as follows: amikacin, 90% and 88%; ciprofloxacin, 63% and 46%; gentamicin, 59% and 67%, imipenem, 99% and 65%; levofloxacin, 69% and 44%; and piperacillin/tazobactam only 40% and 12%. Ceftazidime-resistant GNB exhibited high rates of resistance to other antimicrobials. Cefepime was very active against ceftazidime-resistant enteric GNB (AmpC enzyme producers), especially Enterobacter spp. (94.3% susceptible), Citrobacter spp. (96.7% susceptible), and indole-positive Proteae (89.6% susceptible), and showed activity similar to that of ceftazidime against all P. aeruginosa and Acinetobacter spp. isolated in North American medical centers. Continued resistances surveillance monitoring will be necessary to assess the effectiveness of widely used broad-spectrum antimicrobials as novel resistance mechanisms emerge.     

Multicenter evaluation of the antimicrobial activity for six broad-spectrum beta-lactams in Venezuela: comparison of data from 1997 and 1998 using the Etest method. Venezuelan Antimicrobial Resistance Study Group

The minimum inhibitory concentrations of six broad-spectrum beta-lactam antimicrobial agents were determined in 1998 by use of the Etest versus a total of 502 bacteria in seven Venezuelan hospital laboratories. These data were compared with results of a similar study performed in 1997. The organisms tested included 309 recent clinical isolates of Enterobacteriaceae, 70 Pseudomonas aeruginosa, 54 Acinetobacter species, and 69 oxacillin-susceptible Staphylococcus aureus. Extended spectrum beta-lactamase production was noted among 30% of Klebsiella pneumoniae isolates. Hyperproduction of Amp C cephalosporinase producing resistance to ceftazidime and cefotaxime was observed with 10 to 37% of isolates of Enterobacter spp., Serratia spp., and Citrobacter freundii. The overall rank order of activity of the six beta-lactams tested in this study against all clinical isolates was imipenem (96.6% susceptible) > cefepime (90.4%) > piperacillin/tazobactam (85.7%) > ceftazidime (73.5%) > cefotaxime (70.5%) > piperacillin (55.0%). These findings were very similar to those reported for 1997.     

Geographic variations in activity of broad-spectrum beta-lactams against Pseudomonas aeruginosa: summary of the worldwide SENTRY Antimicrobial Surveillance Program (1997-2000)

With reports of increasing resistance to antimicrobial agents among Pseudomonas aeruginosa clinical isolates worldwide, the activities of cefepime and eight other broad-spectrum beta-lactams against 6969 isolates collected during 1997-2000 from the four regions of the SENTRY Antimicrobial Surveillance Program. P. aeruginosa isolates were tested by the reference broth microdilution method against nine beta-lactam antimicrobial agents (aztreonam, cefepime, ceftazidime, imipenem, meropenem, piperacillin +/- tazobactam, ticarcillin +/- clavulanate), three aminoglycosides (amikacin, gentamicin, tobramycin), and two fluoroquinolones (ciprofloxacin, levofloxacin). The strains were contributed by more than 100 medical centers. National Committee for Clinical Laboratory Standards criteria were used to identify susceptible and resistant isolates. P. aeruginosa strains from Latin America were generally the most resistant to all classes of antimicrobials, compared with strains from other regions. The beta-lactams exhibited a wide range of potency, with carbapenems most active (meropenem, 80-91% susceptible; imipenem, 76-88% susceptible). Piperacillin/tazobactam was the most active penicillin (77-80% susceptible), and cefepime (67-83% susceptible) had an average 2% (range, 0.7-3.5%) greater susceptibility rate than ceftazidime (66-80% susceptible) across all regions. The rank order of beta-lactam activity according to percent resistant isolates in North American P. aeruginosa strains was: meropenem (4.8% resistant) > cefepime (6.8%) > imipenem (8.6%) > piperacillin/tazobactam (10.3%) > piperacillin (12.9%). Only 2.3% and 6.5% of isolates were resistant to amikacin or tobramycin, respectively, and nearly 16% of P. aeruginosa strains were resistant to ciprofloxacin. Compared with other geographic regions, strains of P. aeruginosa remain most susceptible in North America. In all regions, aminoglycosides in combination with carbapenems, cefepime, or piperacillin/tazobactam would provide more potential antipseudomonal activity than fluoroquinolone combinations for wide-spectrum empiric regimens.     

In vitro evaluation of cefepime and other broad-spectrum beta-lactams for isolates in Malaysia and Singapore medical centers. The Malaysia/Singapore Antimicrobial Resistance Study Group

The degree of activity of several beta-lactam antimicrobial agents was assessed in Malaysia (four medical centers) and Singapore (two medical centers) tested against 570 clinical isolates. The organisms were tested locally by the Etest (AB BIODISK, Solna, Sweden) method, validated by concurrent use of quality assurance strains (94.1% accurate performance overall). Ten groups of bacteria were tested against cefepime, cefpirome, ceftazidime, ceftriaxone, piperacillin/tazobactam, oxacillin, and imipenem. Among the tested Escherichia coli and Klebsiella spp., the occurrence of extended spectrum beta-lactamase-producing phenotypes was 5.6-7.0% and 36.7-38.0%, respectively. These strains remained most susceptible (97.5-100.0%) to cefepime and imipenem. Ceftazidime-resistant Enterobacter spp. (21.4% resistant), Citrobacter spp. (15.0%), indole-positive Proteus spp. (6.0%), and Serratia spp. (9.7%) were not resistant to cefepime, and only one strain was resistant to imipenem. Imipenem was generally most potent against non-fermentative Gram-negative bacilli such as Acinetobacter spp. and Pseudomonas aeruginosa. All tested beta-lactams were active against the oxacillin-susceptible staphylococci, except ceftazidime (MIC90, 12 micrograms/mL; 63.2-84.8% susceptibility rates). Overall spectrums of activity (rank by % resistance) favored imipenem (3.5%) > cefepime (7.7%) > cefpirome (8.9%) > piperacillin/tazobactam (13.2%) > ceftriaxone (14.7%) > ceftazidime (16.9%). No significant differences in resistance patterns were noted between monitored nations, and these results indicate emerging, elevated rates of resistance versus the studied broad-spectrum beta-lactams in Malaysia and Singapore. Results provide benchmark data for future studies using quantitative methods to determine antimicrobial resistance in these geographic areas.     

Activity and spectrum of 22 antimicrobial agents tested against urinary tract infection pathogens in hospitalized patients in Latin America: report from the second year of the SENTRY antimicrobial surveillance program (1998)

The potency and spectrum of various antimicrobial agents tested against 434 bacterial isolates causing urinary tract infection (UTI) in hospitalized patients in Latin America were evaluated. The genotypes of the extended-spectrum beta-lactamase-producing and selected multi-resistant isolates were also evaluated by molecular typing techniques. Escherichia coli (60.4%) was the most common aetiological agent causing UTI, followed by Klebsiella spp. (11.2%) and Pseudomonas aeruginosa (8.3%). In contrast, Enterococcus spp. isolates caused only 2.3% of UTIs. Fewer than 50% of E. coli isolates were susceptible to broad-spectrum penicillins. The resistance rates to ciprofloxacin and the new quinolones were also high among these isolates. The molecular characterization of ciprofloxacin-resistant E. coli showed that most of them have a double mutation in the gyrA gene associated with a single mutation in the parC gene. The Klebsiella pneumoniae isolates studied demonstrated high resistance rates to beta-lactam drugs, including broad-spectrum cephalosporins. The carbapenems were the compounds with the highest susceptibility rate among these isolates (100.0% susceptible) followed by cefepime (91.7% susceptible). Meropenem, imipenem and cefepime were also the most active drugs against Enterobacter spp. Among P. aeruginosa isolates, meropenem (MIC(50), 2 mg/L) was the most active compound, followed by imipenem (MIC(50), 4 mg/L), cefepime (MIC(50), 8 mg/L) and ceftazidime (MIC(50), 16 mg/L). The results presented in this report confirm that bacterial resistance continues to be a great problem in Latin American medical institutions.     

In vitro evaluation of cefepime and other broad-spectrum beta-lactams against bacteria from Indonesian medical centers. The Indonesia Antimicrobial Resistance Study Group

The in vitro activity of cefepime and six other broad-spectrum beta-lactams (cefpirome, ceftazidime, ceftriaxone, imipenem, piperacillin/tazobactam (4 micrograms/mL fixed concentration), and oxacillin was evaluated against 191 isolates of clinical bacteria from Indonesia. Susceptibility testing was performed using Etest (AB BIODISK, Solna, Sweden) methodology. Isolates from 10 species groups were selected for analysis: Escherichia coli, Klebsiella spp., Enterobacter spp., indole-positive Proteae, Serratia spp., Acinetobacter spp., Pseudomonas aeruginosa, and oxacillin-susceptible staphylococci. The overall rank order of spectrum of activity was (% resistant): imipenem (2.2%) > cefepime (7.3%) > piperacillin/tazobactam > cefpirome > ceftazidime > ceftriaxone (16.2%). The "fourth-generation" cephalosporins, cefepime and cefpirome, displayed greater activity compared with the "third-generation" cephalosporins, ceftazidime, and ceftriaxone, against the 60 E. coli and Klebsiella spp. (30 each) isolates. Phenotypic extended spectrum beta-lactamase occurrence rates among the E. coli and Klebsiella spp. were 23.3 and 33.3%, respectively. Imipenem, cefepime, and cefpirome inhibited 95.7% of the 46 isolates of inducible Amp C cephalosporinase producing Enterobacteriaceae. The majority of the resistance observed to imipenem and cefepime among tested Indoneisian strains was attributable to the nonfermentative Gram-negative bacilli, P. aeruginosa and Acinetobacter spp. These results indicate the presence of beta-lactam resistance in Indonesia and the need for continued antimicrobial surveillance in this nation and region of the world, preferably using accurate quantitative methods.     

Antibacterial activity of 41 antimicrobials tested against over 2773 bacterial isolates from hospitalized patients with pneumonia: I--results from the SENTRY Antimicrobial Surveillance Program (North America, 1998)

Pneumonia is the second most frequent cause of nosocomial infection, and hospitalization frequently is needed for community-acquired pneumonia. Knowledge of causative pathogens through periodic surveillance, and their prevailing antimicrobial susceptibility patterns becomes paramount in choosing appropriate empiric therapy. The SENTRY Antimicrobial Surveillance Program, tracks pathogen distribution worldwide since 1997 and documents emerging resistance to a wide range of antimicrobial agents. During the respiratory disease season in 1998, each of 30 medical centers (25 in the United States [US], and five in Canada [CAN]) contributed 100 consecutive isolates obtained from hospitalized patients with suspected pneumonia. The 2773 organisms, processed by the monitor consisted of a total of 35 species, with Staphylococcus aureus comprising 25.6% of all isolates and five other species (Pseudomonas aeruginosa 18.7%, Haemophilus influenzae 9.4%, Streptococcus pneumoniae 7.8%, Klebsiella spp. 7.0%, and Enterobacter spp. 6.7%) making up almost 50% of the total. In the US, pneumococci (8.5%) were more prevalent than in CAN (4.1%; p = 0.001). The US isolates of S. pneumoniae were variably susceptible to penicillin (76.8%), with non-susceptible strains demonstrating greater levels of cross resistance to macrolides (31.8%), cefepime (9.0%) and cefotaxime (6.8%), but remaining susceptible to gatifloxacin and quinupristin/dalfopristin. H. influenzae and Moraxella catarrhalis were generally ampicillin-resistant, 40.4-44.4% and 93.7-95.7%, respectively. P. aeruginosa remained very susceptible to amikacin (91.3-93.8%) > tobramycin > meropenem > piperacillin/tazobactam > gentamicin > piperacillin > cefepime (80.0-81.8%). Extended spectrum beta-lactamase phenotypes among the Klebsiella spp. were isolated from five medical centers in the US and were 4.8-6.0% overall; a rate similar to the previous year. Among the US isolates of Enterobacter spp., only 77.6% and 79.6% were susceptible to ceftazidime and cefotaxime, respectively, but >90% were inhibited by cefepime, imipenem, meropenem, aminoglycosides, and fluoroquinolones. Isolates from CAN were generally more susceptible, except for Pseudomonas isolates, where resistance to aminoglycosides, fluoroquinolones and imipenem was greater. The SENTRY Program results outline important national differences in the frequencies of pathogen occurrence, but more importantly, identify unstable patterns of resistance to available antimicrobial drugs, and serves as a reference for results of other local, national or international investigations.     

In vitro evaluation of cefepime and other broad-spectrum beta-lactams in Taiwan medical centers. The Taiwan Antimicrobial Resistance Study Group

The rates of resistance to commonly used antimicrobial agents have been documented to be at alarmingly high levels in Taiwan for both Gram-positive and Gram-negative species. This study was conducted to assess the current resistance patterns in six medical centers strictly controlled using a common MIC methodology and quality assurance measures. Cefepime, a new clinically introduced broad-spectrum "fourth-generation" cephalosporin, was compared to other members in this class including ceftazidime, cefpirome, ceftriaxone, piperacillin/tazobactam, and imipenem. These antimicrobials were tested against ten species groups of common clinical isolates of Enterobacteriaceae, non-enteric Gram-negative bacilli, and oxacillin-susceptible Staphylococcus spp. The results confirmed that extended spectrum beta-lactamase (ESBL) production in Klebsiella spp. (21.7%) and Escherichia coli (16.7%) was common in all medical centers surveyed. Cefepime was more active against these two species as well as against Amp C producing species, indole-positive Proteae, and Acinetobacter species. The activity of cefepime was comparable although slightly less than that of ceftazidime against Serratia spp. and Pseudomonas aeruginosa strains. All or nearly all staphylococci isolates were susceptible to the beta-lactam antimicrobial agents, except for ceftazidime. Overall, these antimicrobial agents had descending spectrums of activity as follows: imipenem > cefepime > cefpirome > piperacillin/tazobactam > ceftazidime > ceftriaxone for the 550 isolates tested. Cefepime seems to be an important broad-spectrum beta-lactam that can be used with confidence against many important pathogens in Taiwan, including those harboring resistance mechanisms. A continued surveillance program seems prudent for this geographic area.     

2005年北京协和医院细菌耐药性监测

目的监测北京协和医院2005年临床分离株的耐药谱。方法收集患者首次非重复分离株4702株,其中革兰阴性菌63.2%,革兰阳性菌36.8%。以CLSI推荐的纸片扩散法测定其抗菌药物敏感性,用WHONET5.3软件分析结果。结果大肠埃希菌、肺炎克雷伯菌和产酸克雷伯菌对碳青霉烯类最敏感(99.7%～100%),其敏感率在80%以上的药物为哌拉西林-三唑巴坦、阿米卡星、头孢他啶和头孢西丁,而对头孢噻肟敏感率仅为48.9%～78.8%。肠杆菌属、柠檬酸杆菌属、沙雷菌属对碳青霉烯类、阿米卡星和头孢吡肟敏感率较高,为87.7%～100%,肠杆菌属和柠檬酸杆菌属对头孢西丁的耐药率分别为84.5%和50.0%,而沙雷菌属耐药率仅为12.5%,但有31.2%中介。铜绿假单胞菌对阿米卡星、美罗培南、亚胺培南、哌拉西林-三唑巴坦较敏感(70.5%～71.9%),对其他药物敏感率均低于65%。鲍曼不动杆菌对亚胺培南敏感率为70.7%,而对美罗培南敏感率仅为41.4%,对头孢哌酮-舒巴坦和氨苄西林-舒巴坦耐药率分别仅为25.1%和35.5%,对其他药物耐药率均高达58.5%～89.7%。所有葡萄球菌对万古霉素100%敏感,MRSA和MRCNS的检出率分别为57.9%和85.5%,MRSA对复方磺胺甲噁唑和MRCNS对利福平的敏感率均接近80%,对其他药物均较耐药。MSSA和MSCNS对头孢菌素类敏感率均在95%以上。屎肠球菌和粪肠球菌对万古霉素和替考拉宁最敏感(99.3%,98.3%),未检出耐万古霉素的肠球菌属。结论肠杆菌科细菌对碳青霉烯类仍最为敏感,但不发酵糖菌对其耐药率升高。葡萄球菌属和肠球菌属中均未发现耐万古霉素菌株。     

In vitro activity of newer broad spectrum beta-lactam antibiotics against enterobacteriaceae and non-fermenters: a report from Austrian intensive care units. Austrian Carbapenem Susceptibility Surveillance Group.

We compared the in vitro activity of broad spectrum beta-lactam antibiotics against 573 gram-negative isolates (enterobacteriaceae and non-fermenters) collected between November 1996 and May 1997 from 9 laboratories serving intensive care units throughout Austria. MIC's (Minimal Inhibitory Concentration) were obtained with the E-test for meropenem, imipenem, ceftazidime, cefepime, cefpirome and piperacillin/tazobactam. Pseudomonas aeruginosa was the most frequently isolated organism (22%), followed by E. coli (19%), Klebsiella spp. (16%), and Enterobacter spp. (14%). Acinetobacter spp., Proteus spp., Serratia spp., Stenotrophomonas maltophilia, Citrobacter spp., Morganella morganii, Burkholderia cepacia and Salmonella enteritidis were isolated less frequently. Overall meropenem, imipenem and ceftazidime were the most active compounds in vitro, inhibiting 90%, 89%, and 87% of the isolates, respectively. Pseudomonas aeruginosa was inhibited by piperacillin/tazobactam in 89%, by cefepime in 87% and by ceftazidime in 85%. Imipenem, meropenem and cefpirome were less active (79%, 75% and 69% respectively). All E. coli strains were inhibited by meropenem, 99% were inhibited by imipenem, cefepime and cefpirome. Ceftazidime was active against 95% and piperacillin/tazobactam against 92% of E. coli. All Klebsiella spp. were inhibited by meropenem, cefepime and cefpirome. Imipenem inhibited 99% and ceftazidime 98% of the Klebsiella isolates. Piperacillin/tazobactam was active against 95% of Klebsiella spp. In vitro carbapenems are still the most active of all antibiotics tested. The relatively high resistance of Pseudomonas spp. and Acinetobacter spp. to carbapenems reflects the wide use of carbapenems during the last years. However, most bacterial isolates are still sensitive to the tested broad spectrum beta-lactams.     

Urinary tract infection trends in Latin American hospitals: report from the SENTRY antimicrobial surveillance program (1997-2000)

Urinary tract infections (UTI) are one of the most common infectious diseases diagnosed in outpatients as well as in hospitalized patients. The objective of this study was to report the frequency of occurrence and antimicrobial susceptibility of uropathogens collected in Latin America between 1997 to 2000 through the SENTRY Antimicrobial Surveillance Program. Antimicrobial susceptibility testing was performed and results interpreted using reference broth microdilution methods. In the 4 year period, a total of 1961 urine isolates from hospitalized patients were included. The patients' mean age was 51.3 years and most of the infections occurred among women (65.6%). Esherichia coli was the most frequent pathogen isolated followed by Klebsiella spp., Pseudomonas aeruginosa, and Proteus mirabilis. Among the E. coli isolates, piperacillin/tazobactam, aztreonam, extended-spectrum cephalosporins, carbapenems and amikacin constitute reasonable therapeutic options for treatment of serious UTI in Latin America (91.0-100.0% susceptible). High resistance rates to fluoroquinolones (17.5-18.9%) and trimethoprim/sulfamethoxazole (>45.0%) were observed among the E. coli. In contrast, nitrofurantoin displayed susceptibility rate of > 87.0%. Against Klebsiella spp. infections, the only effective therapeutic option would be the carbapenems due to the high number of isolates (>30.0%) producing extended-spectrum beta-lactamases (ESBL). Even the new fluoroquinolones showed limited activity against Klebsiella spp. (72.1-88.6% susceptible) and the P. aeruginosa isolates showed high resistance rates to most antimicrobial agents tested. The results of this survey endorse the importance of Enterobacteriaceae as cause of UTI in Latin America. Our results also demonstrate that the uropathogens isolated in the Latin American medical centers exhibit high resistance to various classes of antimicrobial agents. Carbapenem-resistant P. aeruginosa, ciprofloxacin-resistant E. coli, ESBL-producing K. pneumoniae constitute serious problem in this geographic region.     

Multicenter evaluation of antimicrobial resistance to six broad-spectrum beta-lactams in Colombia: comparison of data from 1997 and 1998 using the Etest method. The Colombian Antimicrobial Resistance Study Group

The minimum inhibitory concentrations of six broad-spectrum beta-lactam antimicrobial agents were determined in 1998 by use of the Etest versus a total of 823 bacteria in 11 Colombian hospital laboratories. These data were compared with results of a similar study conducted in 1997. The organisms tested included 532 recent clinical isolates of Enterobacteriaceae, 108 Pseudomonas aeruginosa, 94 Acinetobacter species, and 89 oxacillin-susceptible Staphylococcus aureus. Extended-spectrum beta-lactamase production was noted among 27.8 to 33.9% of Escherichia coli isolates and 41.7 to 46.7% of Klebsiella spp. isolates. Hyperproduction of Amp C cephalosporinases was observed with 10.5 to 31.4% of isolates of Enterobacter spp., Serratia spp., and Citrobacter spp. An increase in resistance to all of the beta-lactams was observed among Enterobacteriaceae, Acinetobacter spp. and P. aeruginosa when 1998 results were compared with those obtained in 1997. The overall rank order of activity of the six beta-lactams tested in 1998 versus all clinical isolates was imipenem (93.2% susceptible) > cefoperazone/sulbactam (84.1%) > cefepime (80.9%) > ceftazidime (70.7%) > aztreonam (65.7%) > cefotaxime (65.6%). In contrast, the rank order of these same agents tested against a similar collection of Colombian isolates in 1997 was imipenem (96.6% susceptible) > cefepime (93.6%) > cefoperazone/sulbactam (90.5%) > cefotaxime (74.9%) > aztreonam (74.3%) > ceftazidime (73.2%).     

中国14家教学医院院内菌血症与肺炎和腹腔感染病原菌的抗生素耐药监测

目的 监测2006年10月-2007年10月我国不同地区14家教学医院分离的院内获得病原菌的分布和体外药物敏感性.方法 收集来自于院内菌血症、肺炎和腹腔感染患者标本的病原菌.菌株经中心实验室复核后,采用琼脂稀释法测定29种抗菌药物对菌株的MICs,数据输入WHONET5.4软件进行耐药性分析.结果 本研究共收集到2 660株病原菌.引起菌血症(BSI)的病原菌中分离率位于前3位的分别为大肠埃希菌(30.0%)、肺炎克雷伯菌(12.O%)和金黄色葡萄球菌(11.2%);引起院内获得性肺炎(HAP)的病原菌中分离率位于前3位的分别为铜绿假单胞菌(23.4%)、鲍曼不动杆菌(17.4%)和肺炎克雷伯菌(13.8%);引起腹腔感染(IAI)的病原菌中分离率位于前3位的分别为大肠埃希菌(38.8%)、肺炎克雷伯菌(10.2%)和铜绿假单胞菌(9.2%).对于大肠埃希菌和克雷伯菌,敏感性大于80%的药物包括替加环素(100%)、美罗培南(99.3%～100%)、亚胺培南(98.5%～100%)和哌拉西林/三唑巴坦(83.8%～95.1%),氟喹诺酮类药物的敏感性为12.4%～44.9%.对于肠杆菌属、柠檬酸杆菌属、沙雷菌属,替加环素的敏感性为99.2%-100%,亚胺培南和美罗培南的敏感性为96.6%-100%.另外,敏感性较高的抗菌药物还有阿米卡星(82.8%～96.6%)、哌拉西林/三唑巴坦(73.4%～93.1%)、头孢吡肟(69.O%～82.8%)和头孢哌酮/舒巴坦(72.6%～75.9%),氟喹诺酮类药物的敏感性为55.2%-82.8%.多苇耐药的铜绿假单胞菌和鲍曼不动杆菌的发生率分别为18.7%和54.O%.多黏菌素B对铜绿假单胞菌的敏感性最高(93.5%),其次为阿米卡星和哌拉西林/三唑巴坦(均为75.1%).多黏菌素B对鲍曼不动杆菌的敏感性最高(96.2%),其次为替加环素(92.1%)、亚胺培南(59.4%)、米诺环素(59.4%)和美罗培南(56.5%).金黄色葡萄球菌中MRSA的发生率为64.5%,凝同酶阴性葡萄球菌巾MRSCoN的发生率为82.8%.所有葡萄球菌对替加环素、万古霉素和替考拉宁的均敏感.本次监测中发现9株万古霉素耐药的肠球菌(VRE),VRE发生率为4.3%.结论 替加环素、碳青霉烯类、哌拉西林/三唑巴坦、阿米卡星和头孢吡肟对医院分离的肠杆菌科菌保持较高的抗菌活性;多黏菌素B对铜绿假单胞菌和鲍曼不动杆菌均体现出高抗菌活性,鲍曼不动杆菌对替加环素的敏感率达92.1%;替加环素、万古霉素和替考拉宁对院内革兰阳性球菌保持高的抗菌活性.