Development of a rapid detection method for the macrolide resistance gene in Mycobacterium avium using the amplification refractory mutation system-loop-mediated isothermal amplification method.

Macrolide antibiotics such as clarithromycin (CLR) and azithromycin are the key drugs used in multidrug therapy for Mycobacterium avium complex (MAC) diseases. For these antibacterial drugs, drug susceptibility has been correlated with clinical response in MAC diseases. We have previously demonstrated the correlation between drug susceptibility and mutations in the 23S rRNA gene, which confers resistance to macrolides. Herein, we developed a rapid detection method using the amplification refractory mutation system (ARMS)-loop-mediated isothermal amplification (LAMP) technique to identify mutations in the 23S rRNA gene of M. avium. We examined the applicability of the ARMS-LAMP method to genomic DNA extracted from six genotypes of M. avium clinical isolates. The M. avium isolates were classified into 21 CLR-resistant and 9 CLR-susceptible strains based on the results of drug susceptibility tests; the 23S rRNA genes of these strains were sequenced and analyzed using the ARMS-LAMP method. Sequence analysis revealed that the 9 CLR-sensitive strains were wild-type strains, whereas the 21 CLR-resistant strains comprised 20 mutant-type strains and one wild-type strain. Using ARMS-LAMP, no amplification from genomic DNAs of the 10 wild-type strains was observed using the mutant-type mismatch primer sets (MTPSs); however, amplification from the 20 mutant-type strain DNAs was observed using the MTPSs. The rapid detection method developed by us integrates ARMS-LAMP with a real-time turbidimeter, which can help determine drug resistance in a few hours. In conclusion, ARMS-LAMP might be a new clinically beneficial technology for rapid detection of mutations.IMPORTANCEMultidrug therapy for pulmonary Mycobacterium avium complex disease is centered on the macrolide antibiotics clarithromycin and azithromycin, and resistance to macrolides is an important prognosticator for clinical aggravation. Therefore, it is important to develop a quick and easy method for detecting resistance to macrolides. Drug resistance is known to be correlated with mutations in macrolide resistance genes. We developed a rapid detection method using amplification refractory mutation system (ARMS)-loop-mediated isothermal amplification (LAMP) to identify a mutation in the 23S rRNA gene, which is a macrolide resistance gene. Furthermore, we examined the applicability of this method using M. avium clinical isolates. The rapid method developed by us for detection of the macrolide resistance gene by integrating ARMS-LAMP and a real-time turbidimeter can help in detection of drug resistance within a few hours. Since this method does not require expensive equipment or special techniques and shows high analytical speed, it would be very useful in clinical practice.

Bacteraemia and obstructive pyelonephritis caused by Bifidobacterium breve in an elderly woman: a case report and literature review.

Bifidobacterium spp. are non-spore-forming Gram-positive anaerobes that are indigenous to the human gastrointestinal tract and vagina. They are believed to be non-pathogenic organisms for humans and thus are widely used as probiotics. An 83-year-old woman taking cephalexin for 4 days was diagnosed with obstructive pyelonephritis. Y-branched Gram-positive rods were found in both anaerobic and aerobic blood culture bottles, and in an anaerobic urine culture. Bifidobacterium breve was finally identified. Ceftriaxone and metronidazole were administered to the patient, and she was discharged after intermittent catheterization for dysuria. Urinary tract infection caused by Bifidobacterium spp. is believed to be rare, but it can develop in patients with underlying urological conditions. Recognition of the characteristic morphology and conducting anaerobic urine culture may help in identifying more cases of Bifidobacterium urinary tract infections.

Mycobacterium obuense bacteremia: A case report and literature review.

An 84-year-old man visited our hospital with a high fever. He had cut his right index finger 7 days previously. Blood culture became positive on day 3. Gram staining was negative, and acid-fast staining was positive. The organism was subsequently identified as Mycobacterium obuense using a MALDI Biotyper. M. obuense was also detected in the soil at the patient's house, suggesting that it had entered his bloodstream through the cut on his finger. He was treated with a combination of imipenem/cilastatin, amikacin, and clarithromycin for 2 weeks. His clinical condition improved, and he was discharged after 2 weeks and was prescribed clarithromycin and levofloxacin therapy. Only two cases of human infection with M. obuense have been reported previously.

First Case Report of Peritoneal Dialysis-associated Peritonitis Caused by Lysinibacillus sphaericus.

We herein report a case of peritoneal dialysis-associated peritonitis caused by Lysinibacillus sphaericus in a 40s-year-old patient. Treatment was initiated with intermittent intraperitoneal cefazolin and ceftazidime. Later, both peritoneal dialysate and blood cultures detected L. sphaericus, so the antibiotic was changed to ampicillin (ABPC). The patient was treated with a combination of intraperitoneal intermittent and intravenous ABPC for 7 days, followed by 14 days of amoxicillin. The patient experienced no adverse events and no recurrence for 30 days. The patient had four dogs, and the infection was deemed likely to have been caused by environmental contamination and inadequate catheter replacement.

Active surveillance in response to the identification of a single carbapenemase-producing Escherichia coli at a Japanese university hospital.

This report described the experience of active surveillance culture implemented in response to the identification of a single carbapenemase-producing Escherichia coli in a Japanese university hospital. It revealed a horizontal transmission event and an additional asymptomatic carrier of carbapenemase-producing Escherichia coli with unique drug susceptibility and resistance gene profiles. Early implementation of active surveillance culture as a part of multifaceted infection control measures appeared to be useful to control further transmission of carbapenemase-producing Escherichia coli even in the low endemic facility. Further investigations on the timing and usefulness of active surveillance culture in the control of carbapenemase-producing Enterobacteriaceae would be warranted.