BACKGROUNDIn the present study, we characterized multidrug-resistant Pseudomonas aeruginosa (MDRP) clinical isolates from a paediatric facility and investigated the types and features of the metallo-beta-lactamases (MBLs) produced by carbapenem-resistant strains.

METHODSFour hundred and ninety-eight strains of Pseudomonas aeruginosa were isolated from patients at Beijing Children's Hospital between January 2005 and December 2006. The minimal inhibition concentrations (MICs) of the strains for 13 antibiotics were measured. A combination of the E test and PCR amplification/DNA sequencing was used to define the carbapenem-resistant strains.

RESULTSWe found that 24.1% (120/498) of the isolates were MDRP. The frequencies of resistance to imipenem and meropenem were 34.2% and 35.8%, respectively, and the MIC50 and MIC90 values for the two antibiotics were identical at 4 microg/ml and 32 microg/ml, respectively. The detection rate for carbapenem resistance was 49.2% (59/120). Among the 59 carbapenem-resistant Pseudomonas aeruginosa strains, 39 (66.1%) were positive for the MBL genotype; 35 (89.7%) strains carried the bla(IMP) gene and 4 (10.3%) strains carried the bla(VIM) gene. Neither bla(SPM) nor bla(GIM) was amplified from any of the 59 isolates. DNA sequencing revealed that IMP-1 was present in 35 IMP-producing isolates and VIM-2 was detected in four VIM-producing isolates.

CONCLUSIONSThese MDRP isolates exhibited high frequencies of resistance to carbapenems among clinical isolates from a paediatric facility in Beijing, China. The production of MBL appears to be an important mechanism for carbapenem resistance in Pseudomonas aeruginosa.

Carbapenems ; pharmacology ; Child ; Drug Resistance, Multiple, Bacterial ; Humans ; Microbial Sensitivity Tests ; Pseudomonas aeruginosa ; drug effects ; enzymology ; Sequence Analysis, DNA ; beta-Lactamases ; biosynthesis ; classification ; genetics

PURPOSE: This retrospective study was done to evaluate the status of nosocomial urinary tract infections and to determine the risk factors andtransmission route of causal IRPA through molecular epidemiology. METHOD: Two hundred ninety-nine of 423 patients admitted to the internal medicine and surgery ICU at a university hospital incity B had a positiveurine culture. Twelve of the 299 patients who had a urinary tract infection had IRPA strains. The data was collected from November 1, 2004 to January 31, 2005. The following results were obtained after the data was analyzed using percentile and UPGMA. RESULT: The rate of nosocomial urinary tract infections in the ICU was 10.8%. Therewere 16.8 cases of infection based on the period of hospitalization. There were 16.9 cases of infection based on the use of a foley catheter. The rate of nosocomial urinary tract infection in the ICU and urinary tract infections related to IRPA were higher in patients with the following characteristics: men, old age, admission through the emergency room, longer than seven days admission, severity of admitting causes, disturbance of consciousness, hydration less than 300cc in 24hours, a long course of antibiotics, a long period of foley catheterization and perineal care. Most of the microorganisms that caused the urinary tract infection were gram negative bacilli, among which P. aeruginosa was found in 70 patients (18.5%) and IRPA in 12 (4.0%). Among the 12 IRPA strains that were tested with PFGE, eight showed a dice coefficient higher than 80%, suggesting a genetic relationship. They were related with the period of hospitalization in the same ICU. These patients all received direct care for a urinary tract infection. CONCLUSION: Through these results, IRPA can be consideredas a contributing factors to urinary tract infections thus, active preventative measures are needed by the medical staff.
Adult ; Aged ; Aged, 80 and over ; Anti-Bacterial Agents/*pharmacology ; Cross Infection/*epidemiology/etiology/microbiology ; Drug Resistance, Bacterial ; Female ; Humans ; Imipenem/*pharmacology ; Intensive Care Units ; Male ; Middle Aged ; Pseudomonas Infections/drug therapy/*epidemiology ; Pseudomonas aeruginosa/classification/drug effects/*genetics ; Retrospective Studies ; Risk Factors ; Urinary Catheterization ; Urinary Tract Infections/*epidemiology/etiology/microbiology