Antimicrobial susceptibility of Gram-negative bacteria in Brazilian hospitals: the MYSTIC Program Brazil 2003.

Establish the susceptibility pattern of Gram-negative bacteria causing infections in ICU patients, MYSTIC Program Brazil 2003. Gram-negative bacteria (n = 1,550) causing nosocomial infections were collected at 20 Brazilian centers. The central laboratory confirmed the identification and performed the susceptibility tests by Etest methodology (AB Biodisk, Solna, Sweden) for meropenem, imipenem, ciprofloxacin, ceftazidime, cefepime, cefotaxime, piperacillin/tazobactam, gentamicin, and tobramycin. Interpretation criteria used were according to National Committee for Clinical Laboratory Standards (NCCLS). Pseudomonas aeruginosa (30.3%) was the most frequent isolate, followed by E. coli (18.6%), Klebsiella pneumoniae (16.9%), Acitenobacter baumannii (8.8%), and Enterobacter cloacae (7.1%). Pseudomonas aeruginosa (n=470) isolates presented susceptibility rates of 64% to meropenem, 63.8% to piperacillin/tazobactam, 63.4% to amikacin, 58.7% to imipenem. Acitenobacter baumannii presented susceptibility rates to meropenem of 97.1%, and 73% to tobramycin. E. coli and K. pneumoniae were highly susceptible to both carbapenems. Carbapenem resistance among the Enterobacteriaceae is still rare in the region. Acitenobacter baumannii and P. aeruginosa presented elevated resistance rates to all antimicrobials. Since they play an important role in nosocomial infections in this environment, the use of empirical combination therapy to treat these pathogens may be justified.

Pseudomonas aeruginosa clonal dissemination in Brazilian intensive care units.

OBJECTIVE: Investigate clonal dissemination of nosocomial multidrug-resistant Pseudomonas aeruginosa isolates within and between Brazilian intensive care units, which participated in the MYSTIC Program Brazil 2002. METHODS: Thirty-six P. aeruginosa isolates resistant to meropenem or imipenem plus at least two of the following drugs: ciprofloxacin, cefepime, ceftazidime or piperacillin/tazobactam were isolated during 2002 at 4 centres in São Paulo and 1 centre in Brasília. Chromosomal restriction fragments obtained with SpeI were separated by pulsed-field gel electrophoresis (PFGE). Electrophoretic patterns were analyzed with GelCompar II v. 2.5. RESULTS: Five major clones were identified (A, B, C, D, G). Clone A was constituted by 8 isolates with indistinguishable PFGE pattern present in 2 centres. Clone B was constituted by 4 indistinguishable isolates predominant in centre 6. Clone C had 3 indistinguishable isolates, with closely related clones (C1-3). Also, Clone D had 3 indistinguishable isolates, with closely related (D1) and possibly related (D2/D3) clones. Clones C and D were present in centre 1. Clone G was constituted by 2 indistinguishable isolates and was present in centre 7. Finally, 8 isolates were unique. Isolates from Centre 4 were unique. CONCLUSIONS: Clonal dissemination was detected within (clones A, B, C, D, and G) and between centres (clone A). These findings are important when analyzing surveillance data, since susceptibility rates may be significantly affected by the dissemination of a resistant clone.

Antimicrobial susceptibility in intensive care units: MYSTIC Program Brazil 2002.

OBJECTIVE: Establish the susceptibility pattern of Gram-negative bacteria causing infections in ICU patients, MYSTIC Program Brazil 2002. MATERIAL AND METHODS: Gram-negative bacteria (n = 503) causing nosocomial infections were collected at seven Brazilian centers. The central laboratory confirmed the identification and performed the susceptibility tests by E-test methodology (AB Biodisk, Solna, Sweden) for meropenem, imipenem, ciprofloxacin, ceftazidime, cefepime, cefotaxime, piperacillin/tazobactam, gentamicin, and tobramycin. Interpretation criteria used were according to National Committee for Clinical Laboratory Standards (NCCLS). RESULTS: Pseudomonas aeruginosa (33%) was the most frequently isolated, followed by A. baumannii (17.1%), K. pneumoniae (12.1%), E. coli (10.5%), and E. cloacae (7.9%). Pseudomonas aeruginosa isolates had susceptibility rates of 67.5% to piperacillin/tazobactam, 59.8% to meropenem, 57.3% to imipenem. A. baumannii presented susceptibility rates to meropenem of 89.5%, 88.4% to imipenem, and 74.4% to tobramycin. E. coli and K. pneumoniae were fully susceptible to both carbapenems. CONCLUSIONS: Carbapenem resistance among Enterobacteriaceae is still rare in this region. A. baumannii and P. aeruginosa presented elevated resistance rates to all antimicrobials. Since these two bacterial species play an important role in nosocomial infections, the use of empirical combination therapy to treat these pathogens may be justified.

In vitro synergy test of meropenem and sulbactam against clinical isolates of Acinetobacter baumannii.

Meropenem and imipenem are often the drugs of choice for the treatment of infections due to multidrug-resistant Acinetobacter baumannii. The present study aimed at evaluating the interaction between meropenem and sulbactam through microdilution and checkerboard methods against 48 clinical isolates of A. baumannii collected from Brazilian hospitals. All the isolates presented elevated minimum inhibitory concentration (>or=2 microg/mL) to either meropenem or sulbactam. The checkerboard method with the combination of meropenem and sulbactam demonstrated 29.2% (14/48) synergism, 47.9% (23/48) partial synergism, 10.5% (5/48) additive, 6.2% (3/48) indifference, and 6.2% (3/48) antagonism (SigmaFIC(min)=0.09 and SigmaFIC(max)=8). Thus, combinations of meropenem and sulbactam may show synergism or partial synergism for most A. baumannii isolates. Further studies may help identify treatment options for patients with infections caused by these organisms, particularly with this combination, where both drugs have time-dependent activities and might be suitable for therapy optimization studies.

Antimicrobial susceptibility of Gram-negative bacteria in Brazilian hospitals: the MYSTIC Program Brazil 2003

Establish the susceptibility pattern of Gram-negative bacteria causing infections in ICU patients, MYSTIC Program Brazil 2003. Gram-negative bacteria (n = 1,550) causing nosocomial infections were collected at 20 Brazilian centers. The central laboratory confirmed the identification and performed the susceptibility tests by Etest methodology (AB Biodisk, Solna, Sweden) for meropenem, imipenem, ciprofloxacin, ceftazidime, cefepime, cefotaxime, piperacillin/tazobactam, gentamicin, and tobramycin. Interpretation criteria used were according to National Committee for Clinical Laboratory Standards (NCCLS). Pseudomonas aeruginosa (30.3 percent) was the most frequent isolate, followed by E. coli (18.6 percent), Klebsiella pneumoniae (16.9 percent), Acitenobacter baumannii (8.8 percent), and Enterobacter cloacae (7.1 percent). Pseudomonas aeruginosa (n=470) isolates presented susceptibility rates of 64 percent to meropenem, 63.8 percent to piperacillin/tazobactam, 63.4 percent to amikacin, 58.7 percent to imipenem. Acitenobacter baumannii presented susceptibility rates to meropenem of 97.1 percent, and 73 percent to tobramycin. E. coli and K. pneumoniae were highly susceptible to both carbapenems.Carbapenem resistance among the Enterobacteriaceae is still rare in the region. Acitenobacter baumannii and P. aeruginosa presented elevated resistance rates to all antimicrobials. Since they play an important role in nosocomial infections in this environment, the use of empirical combination therapy to treat these pathogens may be justified.

Antimicrobial susceptibility in intensive care units: MYSTIC Program Brazil 2002

OBJECTIVE: Establish the susceptibility pattern of Gram-negative bacteria causing infections in ICU patients, MYSTIC Program Brazil 2002. MATERIAL AND METHODS: Gram-negative bacteria (n = 503) causing nosocomial infections were collected at seven Brazilian centers. The central laboratory confirmed the identification and performed the susceptibility tests by E-test methodology (AB Biodisk, Solna, Sweden) for meropenem, imipenem, ciprofloxacin, ceftazidime, cefepime, cefotaxime, piperacillin/tazobactam, gentamicin, and tobramycin. Interpretation criteria used were according to National Committee for Clinical Laboratory Standards (NCCLS). RESULTS: Pseudomonas aeruginosa (33 percent) was the most frequently isolated, followed by A. baumannii (17.1 percent), K. pneumoniae (12.1 percent), E. coli (10.5 percent), and E. cloacae (7.9 percent). Pseudomonas aeruginosa isolates had susceptibility rates of 67.5 percent to piperacillin/tazobactam, 59.8 percent to meropenem, 57.3 percent to imipenem. A. baumannii presented susceptibility rates to meropenem of 89.5 percent, 88.4 percent to imipenem, and 74.4 percent to tobramycin. E. coli and K. pneumoniae were fully susceptible to both carbapenems. CONCLUSIONS: Carbapenem resistance among Enterobacteriaceae is still rare in this region. A. baumannii and P. aeruginosa presented elevated resistance rates to all antimicrobials. Since these two bacterial species play an important role in nosocomial infections, the use of empirical combination therapy to treat these pathogens may be justified.

Klebsiella pneumoniae with multiple antimicrobial resistance.

A Klebsiella pneumoniae strain was isolated from the urine of a patient at one of the centers participating in the 2001 edition of the MYSTIC program in Brazil. The initial phenotypic findings of the isolated K. pneumoniae presented an unusual MIC of 8 microg/mL to meropenem, 2 microg/mL to imipenem, elevated MICs to broad spectrum cephalosporins (ceftazidime/cefotaxime/cefepime MIC > 256 microg/mL), aminoglycosides (gentamycin > 256 microg/mL and tobramycin = 48 microg/mL), piperacillin/tazobactam (MIC > 256 microg/mL) and susceptibility to ciprofloxacin (MIC = 0.25 microg/mL). The strain also tested positive for ESBL production with double-disk and E-test methodologies. More detailed investigation revealed that the strain produced a SHV-4 type enzyme and also lacked a 36 kDa outer membrane porin.

Klebsiella pneumoniae with multiple antimicrobial resistance

A Klebsiella pneumoniae strain was isolated from the urine of a patient at one of the centers participating in the 2001 edition of the MYSTIC program in Brazil. The initial phenotypic findings of the isolated K. pneumoniae presented an unusual MIC of 8 ìg/mL to meropenem, 2 ìg/mL to imipenem, elevated MICs to broad spectrum cephalosporins (ceftazidime/cefotaxime/cefepime MIC > 256 ìg/mL), aminoglycosides (gentamycin > 256 ìg/mL and tobramycin = 48 ìg/mL), piperacillin/tazobactam (MIC > 256 ìg/mL) and susceptibility to ciprofloxacin (MIC = 0.25 ìg/mL). The strain also tested positive for ESBL production with double-disk and E-test methodologies. More detailed investigation revealed that the strain produced a SHV-4 type enzyme and also lacked a 36 kDa outer membrane porin.