Bo Ra Son

Dipicolinic acid-based disk methods for detection of metallo-β-lactamase-producing Pseudomonas spp. and Acinetobacter spp.

We evaluated novel and simple dipicolinic acid (DPA)-based phenotypic screening methods to detect metallo-beta-lactamase (MBL)-producing isolates: DPA disk synergy tests and DPA-based disk tests (DPA-imipenem, DPA-meropenem, or DPA-ceftazidime disk tests). Upon testing these methods on 79 MBL-producing and 95 MBL-nonproducing isolates of Pseudomonas spp. and Acinetobacter spp., their specificity and sensitivity were superior or comparable with those of the EDTA-based phenotypic screening methods.

First case of Nocardia nova spinal abscess in an immunocompetent patient

Nocardia are a group of aerobic actinomycetes that are filamentous gram-positive, weakly acid-fast, and cause opportunistic infection in immunocompromised patients. Primary Nocardia infection mostly involves lung, skin and less commonly, the central nervous system (CNS). Among Nocardia CNS infections, spinal infection is extremely rare. We describe the first case of a spinal abscess caused by Nocardia nova in an immunocompetent patient who experienced a penetrating facial injury six months earlier. Nocardia species were isolated from intradural spinal abscesses and identified by 16S rRNA, hsp65 and secA1 sequence analyses. Surgical excision and treatment with amikacin, cefotaxime, and oral erythromycin was successful.

Characterization of Acinetobacter baumannii Co-producing Carbapenemases OXA-23 and OXA-66, and armA 16S Ribosomal RNA Methylase at a University Hospital in South Korea

Background: In the present study, the resistance mechanisms against carbapenems and aminoglyco- sides for 23 strains of multi-drug-resistant Acineto- bacter baumannii isolated at a university hospital were investigated. Methods: The minimal inhibitory concentrations (MICs) were determined via broth microdilution or Etest. The genes encoding OXA-type carbapenemases and 16S rRNA methylase were identified using multiplex PCR, and the amplified products were sequenced. Conju- gation experiments were conducted, and an epi- demiologic study was performed using enterobac- terial repetitive intergenic consensus (ERIC)-PCR. Results: In the isolates, the MICs of the tested ami- noglycosides, including arbekacin, were >1024 μg/ mL; the MICs of aztreonam, cefepime, ceftazidime, and ciprofloxacin ranged from 64 to 128 μg/mL; and the MICs of carbapenem ranged from 32 to 64 μg/ mL, as determined through the broth microdilution test. According to the E-test, the MICs of ampicillin/ sulbactam and colistin were 8 and 0.25 to 0.38 μg/ mL, respectively. Sequence analysis confirmed that all of the isolates expressed carbapenemases OXA- 23 and OXA-66, as well as armA 16S rRNA methy- lase. In addition, ISAba1 was identified upstream of the gene encoding OXA-23. OXA-23 and armA were not transferred to Escherichia coli J53 cells in the transconjugation experiments. ERIC-PCR molecular fingerprinting produced a single pattern in all cases. Conclusion: The co-production of OXA-23 and armA 16S rRNA methylase may be attributed to the multi- drug resistance of the A. baumannii isolates in the present study. Stricter surveillance and more rapid detection are necessary to prevent the spread of this type of resistance in the future. (Korean J Clin Microbiol 2011;14:67-73)

Evaluation of Dipicolinic Acid-Based Mueller Hinton Agar Biplate for Detection of IMP-1 and VIM-2 type Metallo-β -Lactamase in Imipenem Non-susceptible Gram Negative Bacilli

BACKGROUND Since metallo-beta-lactamase (MBL)-producing isolates can hydrolyze carbapenem and also easily transfer the resistance genes to other bacteria, a rapid and accurate detection of MBL has become very important. We evaluated the utility of Mueller Hinton agar (MHA) biplate containing dipicolinic acid (DPA) as a screening method to detect IMP-1 and VIM-2 type MBL-producing isolates. METHODS Based on our preliminary tests using various concentrations of DPA, 200 and 300 microg/mL concentration of DPA were chosen for further study. Bacterial lawns were grown on MHA biplate, one half of which contained DPA while the other did not. The inhibition zone around the imipenem (IPM) disk on both sides of this plate was compared. The stability of DPA in the stored DPA-MHA biplate was also evaluated during three months using two MBL- and one non-MBL-producing isolates. RESULTS When the criterion of a > or =7 mm increase of inhibition zone around the IPM disk on the MHA containing DPA compared to MHA without DPA was used, the sensitivities and specificities were 94.7% and 97.6% for 200 microg/mL DPA-MHA biplate, and 98.2% and 97.6% for 300 microg/mL DPA-MHA biplate, respectively. The activity of the DPA in this biplate was stable for three months. CONCLUSIONS Assays using DPA 300-MHA biplate were highly sensitive and specific for the detection of IMP-1 and VIM-2 type MBL-producing bacteria. In addition, it is easy to perform; so, it may be useful to apply this method for detection of IMP-1 and VIM-2 type MBL in clinical laboratories.

Direct Detection of Methicillin-Resistant Staphylococcus aureus from Blood Cultures Using Three Non-Molecular Methods: PBP2a Latex Agglutination, PBP2a Rapid Immunochromatographic Assay and MRSA-Chromogenic Medium

Background: This study compared three non-molecular methods for the detection of methicillin-resistance directly from blood cultures containing Staphylococcus aureus: penicillin-binding protein (PBP) 2a latex agglutination (LA), PBP2a immunochromatographic assay (ICA) and MRSA chromogenic medium (CM). Methods: Fifty methicillin-resistant S. aureus (MRSA) and 50 methicillin-susceptible S. aureus (MSSA) were seeded into blood-culture bottles. When isolates returned a positive signal, 5 mL of culture was added to serum separator tubes and centrifuged at 1,300 g for 10 min. The pellets were then used as the inoculum for the PBP2a LA, MRSA-CM and PBP2a ICA. The pure colony was used for PBP2a LA test, additionally. Results: The respective sensitivities and specificities were 98 and 100% for PBP2a ICA, and 100 and 100% for MRSA-CM in direct detection of MRSA from positive blood culture. The results of PBP2a LA test using pure colony were entirely compatible with those by mecA gene PCR but the PBP2a LA test using the pellets directly isolated from positive blood culture showed sometimes ambiguous agglutination; its sensitivity and specificity were 78 and 100%, if ambiguous results were scored as negative, and were 90 and 92%, if ambiguous results were scored as positive, respectively. Conclusion: For direct detection of MRSA in positive blood culture, MRSA-CM and PBP2a ICA provided excellent results. The PBP2a LA test using pure colony also gave excellent results but the PBP2a LA test by the direct method using pellet of positive blood culture was slightly less sensitive than the other two methods. (Korean J Clin Microbiol 2012;15:27-31)

A Case of Streptococcus salivarius Meningitis in a Patient with Cerebrospinal Fluid Rhinorrhea after Skull Base Fracture

A Case of Streptococcus salivarius Meningitis in a Patient with Cerebrospinal Fluid Rhinorrhea after Skull Base Fracture Kyeong Seob Shin, Dong Ik Shin, Woo Sub Shim, Byeong Cheol Rim, Il Hun Bae, Seung Young Lee, Dong Hee Ryu, Eun Jung Kim, Bo Ra Son Departments of Laboratory Medicine, Neurology, Otorhinolaryngology-Head and Neck Surgery, Neurosurgery, Radiology and Surgery, Chungbuk National University College of Medicine, Department of Pathology, Chungbuk National University Hospital, Cheongju, Korea

A Case of Granulicatella adiacens Septicemia Identified by 16S rRNA Sequencing Analysis

Granulicatella adiacens is one of the fastidious gram positive cocci previously described as nutritionally variant streptococci due to their requirement of L-cysteine, pyridoxal, or thiol compounds for growth. These bacteria have been identified as significant causative agents of endocarditis, opthalmic infections, and meningitis. We report a case of septicemia caused by G. adiacens in an 80-year-old patient with cholangiocarcinoma. The organism was identified by phenotypic and 16S rRNA sequencing analyses. (Korean J Clin Microbiol 2008;11:63-65)

Kodamaea ohmeri Fungemia in a Patient with Carcinoma of the Ampulla of Vater

or Yamadazyma ohmeri, is an ascosporogenous yeast that belong to the Saccharomycetaceae family, and it is a rare yeast-form fungus recently identified as an etiological agent of fungemia, endocarditis, urinary tract infection and peritonitis in immunocompromised patients. This paper presents a case of K. ohmeri fungemia in a 70-year-old man with carcinoma of the ampulla of Vater. After receiving endoscopic retrograde cholangiopancreatography (ERCP) for releasing obstruction of ampulla of Vater by insertion of the biliary stent, he was pyrexial with a temperature of 38.5°C. Two set of blood samples were obtained from a peripheral vein for culture. The pathogen was identified as K. ohmeri using the Vitek YST card (bioMérieux, France) and was confirmed by the sequencing of the D1/D2 domains of the 26S rRNA gene and the internally transcribed spacer region. The minimal inhibitory concentrations of the antifungal agents were as follows: amphotericin B 0.5 μg/mL; fluconazole 2 μg/mL; voriconazole ≤ 0.12 μg/mL; fluocytosine ≤ 1 μg/mL. According to the Clinical and Laboratory Standard Institute recommended breakpoint for Candida spp, the isolate was susceptible to fluconazole, amphotericin B, voriconazole, and flucytosine. This is the first report of the isolation of K. ohmeri in the patient with a gastrointestinal neoplasm following ERCP.

Group B Streptococcal Toxic Shock-like Syndrome: A Case Report and Review of the Literature

Toxic shock syndrome is an acute and febrile illness that rapidly progress to shock and multi-organ failure, and it is caused by toxin-producing strains of Staphylococcus aureus or Streptococcus species. Streptococcal toxic shock syndrome (STSS) is usually caused by group A streptococci, but non-group A STSS is rare. In this study, we describe a case of STSS caused by Streptococcus agalactiae (group B streptococci) in a patient with alcoholic liver cirrhosis. At arrival in our hospital, the patient had a decreased mental status with hemorrhagic bullae on four extremities, and he progressed to a fatal outcome within 4 days in spite of antibiotic treatment. (Ann Clin Microbiol 2014;17:91-94)