tobramycin and Nocardia-Infections

Topics: Anti-Bacterial Agents; Benzamidines; Drug Therapy, Combination; Eye Infections, Bacterial; Female; Fluorescein Angiography; Humans; Hydroxymercuribenzoates; Keratitis; Nocardia Infections; Tobramycin; Young Adult

To describe the novel use of femtosecond laser technology for therapeutic resection of infectious foci in a case of multidrug-resistant Nocardia asteroides keratitis.. A 30-year-old man presented with a corneal infiltrate. Cultures were taken, and fortified vancomycin and tobramycin were initiated. After 3 negative cultures and minimal improvement on various broad-spectrum antibiotics, all topical medications were stopped and a final fourth corneal culture grew N. asteroides. Treatment with topical amikacin was initiated, but the infection continued to worsen. With drug sensitivities still pending, the patient's clinical status continued to deteriorate rapidly, despite treatment with amikacin, gatifloxacin, and polymyxin B/trimethoprim. The femtosecond laser was then used to perform targeted lamellar keratectomy.. Femtosecond laser-assisted lamellar keratectomy successfully removed the infected tissue and allowed for increased penetration of topical antibiotics. Drug sensitivities finally returned, revealing multidrug resistance and sensitivity only to trimethoprim/sulfamethoxazole and tobramycin, some of which the patient had previously tried and failed. The infection fully resolved after readministering polymyxin B/trimethoprim and tobramycin, leaving minimal residual scarring.. Multidrug-resistant N. asteroides keratitis can be difficult to manage even with appropriate antibiotic therapy based on drug sensitivity testing. Femtosecond laser-assisted resections may facilitate treatment in these cases by safely and precisely debulking infected tissue and enhancing penetration of topical medications.

Topics: Adult; Amikacin; Anti-Bacterial Agents; Corneal Surgery, Laser; Corneal Ulcer; Drug Resistance, Multiple, Bacterial; Eye Infections, Bacterial; Humans; Male; Nocardia asteroides; Nocardia Infections; Tobramycin; Trimethoprim, Sulfamethoxazole Drug Combination

There is a lack of information on the activities of antimicrobial agents against Nocardia clinical isolates of specific species in China. The aim of this study was to determine the antibiotic susceptibility of 28 clinical isolates of Nocardia spp. isolated from Beijing Chao-Yang Hospital (Beijing, China).. Molecular diagnosis of Nocardia spp. was performed using partial 16S rRNA and rpoB gene sequences. Antimicrobial susceptibility testing was performed by broth microdilution according to Clinical and Laboratory Standards Institute (CLSI) recommendations.. The species distribution was as follows: Nocardia cyriacigeorgica (n=13); Nocardia farcinica (n=6); Nocardia beijingensis (n=3); Nocardia abscessus (n=2); Nocardia wallacei (n=2); Nocardia otitidiscaviarum (n=1); and Nocardia nova (n=1). The susceptibility rates to trimethoprim/sulfamethoxazole (SXT), linezolid, amikacin, imipenem, tobramycin, ceftriaxone and cefotaxime were 100.0%, 100.0%, 92.9%, 75.0%, 67.9%, 67.9% and 64.3%, respectively, whilst the resistance rate both to ciprofloxacin and clarithromycin was 71.4%.. N. cyriacigeorgica was the most frequently isolated Nocardia spp. All clinical isolates showed low susceptibility to ciprofloxacin and clarithromycin and complete susceptibility both to SXT and linezolid, which can be considered the primary choice for the treatment of Nocardia infections in China.

Topics: Adult; Aged; Aged, 80 and over; Anti-Bacterial Agents; China; Ciprofloxacin; Clarithromycin; Drug Resistance, Bacterial; Female; Humans; Male; Microbial Sensitivity Tests; Middle Aged; Nocardia; Nocardia Infections; Population Surveillance; Tertiary Care Centers; Tobramycin; Young Adult

Topics: Abscess; Bacterial Typing Techniques; Ceftazidime; Diagnostic Errors; Doxycycline; Drug Therapy, Combination; Eye Infections, Fungal; Genes, Bacterial; Humans; Keratitis; Male; Middle Aged; Nocardia; Nocardia Infections; Tobramycin; Vancomycin

To describe 2 cases of Nocardia keratitis resistant to topical compounded amikacin therapy.. A 24-year-old woman presented with a corneal infiltrate. Cultures were taken, and topical moxifloxacin was administered. Corneal biopsy was performed when clinical status deteriorated, which confirmed infection with Nocardia. The patient was administered topical compounded amikacin. When clinical status further deteriorated, she was switched to compounded trimethoprim-sulfamethoxazole, which resulted in rapid resolution. Separately, a 22-year-old woman presented with contact lens-related keratitis that grew Nocardia asteroides. Corneal cultures and drug sensitivity testing revealed a strain of N. asteroides resistant to amikacin and imipenem, but sensitive to tobramycin. After a protracted clinical course, the keratitis ultimately responded to topical tobramycin leaving the patient with a pericentral corneal scar.. Nocardia keratitis is an atypical infection for which standard management algorithms exist. However, atypical cases require that these patients be followed closely for the response to therapy.

Topics: Administration, Topical; Amikacin; Anti-Bacterial Agents; Contact Lenses, Hydrophilic; Corneal Ulcer; Eye Infections, Bacterial; Female; Humans; Kanamycin Resistance; Microbial Sensitivity Tests; Nocardia asteroides; Nocardia Infections; Ophthalmic Solutions; Tobramycin; Trimethoprim, Sulfamethoxazole Drug Combination; Young Adult

Nocardia farcinica strains showing high-level resistance to amikacin were isolated from clinical cases in a Canada-wide bovine mastitis epizootic. Shotgun cloning of the resistance genes in the amikacin-resistant mastitis isolate N. farcinica IFM 10580 (W6220 [Centers for Disease Control and Prevention]) using a multicopy vector system revealed that the 16S rRNA gene with an A-to-G single-point mutation at position 1408 (in Escherichia coli numbering) conferred "moderate" cross-resistance to amikacin and other aminoglycosides to an originally susceptible N. farcinica strain IFM 10152. Subsequent DNA sequence analyses revealed that, in contrast to the susceptible strain, all three chromosomal 16S rRNA genes of IFM 10580, the epizootic clinical strain, contained the same A1408G point mutations. Mutant colonies showing high-level aminoglycoside resistance were obtained when the susceptible strain N. farcinica IFM 10152 was transformed with a multicopy plasmid carrying the A1408G mutant 16S rRNA gene and was cultured in the presence of aminoglycosides for 3 to 5 days. Of these transformants, at least two of the three chromosomal 16S rRNA genes contained A1408G mutations. A triple mutant was easily obtained from a strain carrying the two chromosomal A1408G mutant genes and one wild-type gene, even in the absence of the plasmid. The triple mutant showed the highest level of resistance to aminoglycosides, even in the absence of the plasmid carrying the mutant 16S rRNA gene. These results suggest that the homozygous mutations in the three 16S rRNA genes are responsible for the high-level aminoglycoside resistance found in N. farcinica isolates of the bovine mastitis epizootic.

Topics: Amikacin; Aminoglycosides; Animals; Anti-Bacterial Agents; Base Sequence; Canada; Cattle; DNA Primers; Drug Resistance, Bacterial; Female; Genes, Bacterial; Homozygote; In Vitro Techniques; Mastitis, Bovine; Microbial Sensitivity Tests; Nocardia; Nocardia Infections; Point Mutation; RNA, Bacterial; RNA, Ribosomal, 16S

Nocardia cyriacigeorgica is a recently described species. During routine diagnostic testing of 121 clinical isolates, we found that about one fourth of the strains from Japan (19 isolates) and Thailand (8 isolates), which were identified in our laboratories as N. asteroides, in fact belong to N. cyriacigeorgica. To our knowledge, this is the first report of infection due to N. cyriacigeorgica in Japan and Thailand, and the third report of infection anywhere in the world. Although N. cyriacigeorgica is usually differentiated from other Nocardia species by utilization of glucose and gluconate, we found that it can also be differentiated by a characteristic synergistic effect between imipenem (IPM) and tobramycin (TOB).

Topics: Adult; Aged; Aged, 80 and over; Anti-Bacterial Agents; Drug Synergism; Female; Humans; Imipenem; Japan; Male; Microbial Sensitivity Tests; Middle Aged; Nocardia; Nocardia Infections; Phylogeny; Polymerase Chain Reaction; RNA, Bacterial; RNA, Ribosomal, 16S; Species Specificity; Thailand; Tobramycin

Among 58 aerobic actinomycetes isolated from different sources and geographical locations, none of 23 Nocardia asteroides isolates, at 18 N. farcinica isolates, 1 of 5 N. otitidiscaviarum isolates, and 1 of 4 Rhodococcus species isolates opacified Middlebrook 7H10 medium. Within the N. asteroides complex, this characteristic, together with growth at 45 degrees C and resistance to each of erythromycin, cefotaxime, and tobramycin, provides a simple means of distinguishing N. farcinica from N. asteroides.

Topics: Actinomycetales; Agar; Animals; Australia; Bacteriological Techniques; Cefotaxime; Culture Media; Drug Resistance, Microbial; Drug Resistance, Multiple; Erythromycin; Fish Diseases; Fishes; Humans; Nephelometry and Turbidimetry; Nocardia; Nocardia asteroides; Nocardia Infections; Species Specificity; Tobramycin