ABSTRACT
An outbreak in a medical intensive care unit was due to an OXA-23-producing Acinetobacter baumannii strain imported from a repatriate hospitalized in Singapore. This outbreak revealed another multidrug resistant epidemic strain that had been present in the hospital for 2 years. Both outbreaks were controlled after 9 months of an extensive infection control program.
Subject(s)
Acinetobacter Infections/epidemiology , Cross Infection/epidemiology , Disease Outbreaks/prevention & control , Disease Outbreaks/statistics & numerical data , Drug Resistance, Multiple, Bacterial , Equipment Contamination/prevention & control , Infection Control/methods , Acinetobacter Infections/prevention & control , Aged , Cross Infection/prevention & control , Female , France , Humans , Intensive Care Units , Male , Middle Aged , SingaporeABSTRACT
Twenty-one isolates of Staphylococcus epidermidis from 9 patients with persistent prosthetic joint infections were analysed by pulsed-field gel electrophoresis and antibiotic susceptibility assays. In 7 of these cases, the S. epidermidis isolate was different from that of the initial episode. In 1 further case, the superinfection was polyclonal. Recurrence, i.e., renewed isolation of a clone identical to that of an initial episode, occurred in 3 cases, 1 of which was in the absence of superinfection. A high degree of antibiotic resistance was demonstrated, including methicillin in 17 of 21 strains. In conclusion, a frequent occurrence of superinfection and a high degree of resistance make management of these infections complex.
Subject(s)
Joint Prosthesis/microbiology , Prosthesis-Related Infections/microbiology , Staphylococcal Infections/microbiology , Staphylococcus epidermidis/isolation & purification , Aged , Aged, 80 and over , Arthroplasty, Replacement, Hip , Arthroplasty, Replacement, Knee , Chronic Disease , Electrophoresis, Gel, Pulsed-Field , Female , Humans , Male , Recurrence , Retrospective Studies , Risk Factors , Staphylococcus epidermidis/genetics , Superinfection/microbiologyABSTRACT
Risk factors for imipenem (IMP)-resistant Pseudomonas aeruginosa (IRPA) digestive carriage were analyzed, and genetic events contributing to select resistant isolates in patients exposed to IMP were investigated. Among the 150 patients with hospital-acquired P. aeruginosa digestive carriage, 38 isolates were IRPA. DNA pulsotypes revealed 16 distinct clones. In 4 patients, a second P. aeruginosa isolate showed resistance to IMP compared with the initial susceptible isolate. By comparing the different oprD sequences between IMP-susceptible P. aeruginosa and IRPA strains, a genetic event was systematically found for each resistant isolate, leading to either the absence of OprD or a truncated porin. The multivariate analysis demonstrated that prior IMP exposure was associated with IRPA carriage. In summary, we confirmed that IMP use selects for IRPA in the gut flora. Cross-transmission, however, was frequently observed in intensive care units. Combining epidemiologic approach and molecular analysis is a powerful tool to delineate mechanisms of emerging resistance.
Subject(s)
Anti-Bacterial Agents/pharmacology , Carrier State/microbiology , Cross Infection/microbiology , Imipenem/pharmacology , Pseudomonas aeruginosa/drug effects , Rectum/microbiology , Adult , Aged , Aged, 80 and over , Bacterial Proteins/genetics , Cohort Studies , Drug Resistance, Bacterial , Electrophoresis, Gel, Pulsed-Field , Female , Humans , Logistic Models , Male , Microbial Sensitivity Tests , Middle Aged , Porins/genetics , Prospective Studies , Pseudomonas aeruginosa/genetics , Pseudomonas aeruginosa/isolation & purification , Risk FactorsABSTRACT
In Escherichia coli, beta-lactam resistance usually depends on beta-lactamase production. AmpC chromosomal cephalosporinase hyperproduction is generally due to mutations in the ampC gene promoter. In order to study ampC expression in E. coli clinical strains, we have compared two methods: conventional and real-time reverse transcription-polymerase chain reaction (RT-PCR). With both methods, ampC mRNA was found to be greatly increased in strains presenting -42 or -32 mutations in the ampC promoter, and moderately increased when a -11 mutation was present in the Pribnow box. Real-time RT-PCR represents a powerful tool combining amplification, fluorescent detection and analysis.
