ABSTRACT
Suspected colonies of methicillin-resistant Staphylococcus aureus (MRSA) on chromogenic, MRSASelect (BioRad) medium were confirmed using routine microbiological methods, and a multiplex real-time PCR (n = 108). Although the specificity of MRSASelect assessed at 24 h of incubation was much higher than that of 48 h (91.4 vs. 60 %), extending the incubation time to 48 h, along with PCR confirmation, increased the total number of true positive samples by 27.8 %. These results provide a cost effective method for sensitive and specific detection of MRSA.
Subject(s)
Bacteriological Techniques/methods , Methicillin-Resistant Staphylococcus aureus/isolation & purification , Molecular Diagnostic Techniques/methods , Staphylococcal Infections/diagnosis , Staphylococcal Infections/microbiology , Humans , Methicillin-Resistant Staphylococcus aureus/genetics , Sensitivity and SpecificityABSTRACT
OBJECTIVE: To systematically evaluate the presumption that the healthy middle ear becomes colonized with organisms via the patent eustachian tube using modern microbiologic techniques. STUDY DESIGN: Sterile saline washings were obtained from the middle ear of patients in a prospective fashion. SETTING: Tertiary/quaternary referral centers. PATIENTS: Pediatric and adult patients undergoing cochlear implantation surgery. INTERVENTION(S): Standard bacterial and viral cultures, and nucleic acid amplification techniques. MAIN OUTCOME MEASURE(S): Identification of organisms. RESULTS: Specimens were obtained from 13 children and 9 adults. No organisms were identified in any of the specimens, either through standard culture or PCR testing. CONCLUSION: The presumption that the healthy middle ear is colonized by bacteria from the nasopharynx is unsubstantiated.
Subject(s)
Ear, Middle/microbiology , Adolescent , Adult , Aged , Bacteria/genetics , Bacteria/isolation & purification , Child , Child, Preschool , Cochlear Implantation , Culture Media , DNA, Bacterial/genetics , DNA, Bacterial/isolation & purification , Ear, Middle/virology , Eustachian Tube/immunology , Eustachian Tube/virology , Female , Humans , Infant , Male , Middle Aged , Nasopharynx/microbiology , Nasopharynx/virology , Otologic Surgical Procedures , Reverse Transcriptase Polymerase Chain Reaction , Specimen HandlingABSTRACT
While most diagnostic processes cease with the detection of the first relevant infectious agent, newer multiplexed molecular methods which provide simultaneous analysis of multiple agents may give a more accurate representation of the true pathogen spectrum in these samples. To examine this in the context of respiratory infections, acute-phase respiratory specimens submitted to our clinical diagnostic microbiology/virology laboratory for our routine VIRAP diagnosis protocol during the spring 2006 peak respiratory infection season were processed in parallel by analysis with Genaco (QiaPlex) ResPlex I and ResPlex II molecular diagnostic panels. A total of 1,742 specimens were examined for 21 relevant targets each. The resulting data reveal that multiple infections are frequent and provide evidence for complex interactions between different infectious agents. Statistically relevant association patterns (both positive and negative) were observed between particular pathogens. While some interactions we observed are substantiated by prior reports in the literature, several specific patterns do not appear to have been reported previously. In addition, we report preliminary clinical evidence which supports a hypothesis that these coinfections are medically relevant and that effective treatment for severe respiratory tract infections will increasingly require diagnosis of all involved pathogens, as opposed to single-pathogen reporting.
