Diversity of Azoles Resistant Aspergillus Species Isolated from Experience and Naïve Soils in Nairobi County and Naivasha Sub-County Kenya

New triazole antifungals voriconazole, itraconazole and posaconazole are recommended for prophylaxis and treatment of both invasive and chronic fungal infections such as aspergillosis and aspergilloma. Emergence of azole-resistant among A. fumigatus isolates have been reported in other countries including Tanzania ascribed to either previous antifungal treatment, prophylaxis or triazoles use in agriculture. The use of azole based fungicides in the robust horticulture in Kenya is a significant risk factor for antifungal resistance. The study proposes to analyze environmental isolates of Aspergillus fumigatus, Aspergillus flavus and Aspergillus niger for the presence of resistance against the triazoles antifungals. Fungicide naïve soils were obtained from uncultivated virgin fields while fungicide experience soils were collected from flower, agricultural and horticultural fields and greenhouses within Naivasha sub-county and Nairobi County. The fungal isolates were subjected to antifungal susceptibility to triazoles using broth micro dilution method. A total of 492 samples were analyzed in Nairobi, 52 isolates were identified and they resistance were as follow: A. fumigatus (32%), A. niger (26.09%), A. flavus (33.33%) and A .terreus (0%) and in Naivasha 44 isolates were isolated out of which 25 were A. fumigatus and its resistance was at 36%. Data were analyses using student T test and showed they no different between resistant and susceptible isolates from the two location. Data generated will serve to inform on the current status of triazoles resistance pattern and to raise concern emerging antifungal resistance in clinical practice

Identification and Functional Analysis of the Nocardithiocin Gene Cluster in Nocardia pseudobrasiliensis.

Nocardithiocin is a thiopeptide compound isolated from the opportunistic pathogen Nocardia pseudobrasiliensis. It shows a strong activity against acid-fast bacteria and is also active against rifampicin-resistant Mycobacterium tuberculosis. Here, we report the identification of the nocardithiocin gene cluster in N. pseudobrasiliensis IFM 0761 based on conserved thiopeptide biosynthesis gene sequence and the whole genome sequence. The predicted gene cluster was confirmed by gene disruption and complementation. As expected, strains containing the disrupted gene did not produce nocardithiocin while gene complementation restored nocardithiocin production in these strains. The predicted cluster was further analyzed using RNA-seq which showed that the nocardithiocin gene cluster contains 12 genes within a 15.2-kb region. This finding will promote the improvement of nocardithiocin productivity and its derivatives production

Nocardia elegans infection: a case report and literature review

A case of disseminated nocardiosis caused by Nocardia elegans in a 72-year-old man with rheumatoid arthritis, treated with tacrolimus and prednisolone, is reported herein. The patient had impaired vision and was diagnosed with endophthalmitis and an abdominal skin abscess. He was started on trimethoprim–sulfamethoxazole treatment, followed by cefepime. The patient was then switched to a combination of imipenem–cilastatin and minocycline. Although the patient survived as a result of surgery and prolonged antibiotic treatment, he eventually lost vision after the infection became resistant to antibiotic treatment. Molecular analysis of samples from the abscess and vitreous fluid confirmed the extremely rare pathogen N. elegans, which accounts for only 0.3–0.6% of infections caused by Nocardia species. This organism is almost always associated with pulmonary infection, and disseminated infections are rare. As with previously reported norcardial infections, the current case was treated successfully with trimethoprim–sulfamethoxazole, carbapenems, and aminoglycosides. However, the clinical characteristics of this organism remain unclear. Further studies are therefore required to develop more effective treatment protocols for disseminated nocardiosis caused by this problematic pathogen

Transcriptional analysis.

<p>The transcription levels of genes in the nocardithiocin gene cluster were compared under nocardithiocin-producing and non-producing conditions. The RPKM values under nocardithiocin-producing conditions are relative to those under non-producing conditions. The graph of RPKM-fold change for each gene is shown under the diagram of the gene cluster.</p

Confirmation of nocardithiocin production.

<p>HPLC analysis of the nocardithiocin production in representative <i>Nocardia pseudobrasiliensis</i> IFM strains. In total, 14 strains were tested (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0143264#pone.0143264.t001" target="_blank">Table 1</a>). The peak pattern did not differ considerably between the strains, therefore representative data are shown. The red line indicates the elution time of nocardithiocin.</p

Bacterial strains used in this study.

<p>*The degree of nocardithiocin production was roughly divided into three levels: +, obvious production; ±, very slight production; -, no production.</p><p>Bacterial strains used in this study.</p

Nocardithiocin gene cluster and predicted biosynthesis scheme.

<p>(A) Organization of genes within the cluster. Each gene is color-coded by its putative function. (B) Proposed nocardithiocin biosynthesis pathway based on the chemical structure and putative gene functions. The dehydrogenation reaction forms a thiazole ring (green), dehydration produces dehydroamino acids (red), and the cyclization of the precursor peptide at serines S1 and S10 forms a pyridine ring. Further modifications by P450 monooxygenase (yellow) and methyltransferase (pink) are also indicated.</p