Lipid A-Ara4N as an alternate pathway for (colistin) resistance in Klebsiella pneumonia isolates in Pakistan.

OBJECTIVES: This study aimed to explore mechanism of colistin resistance amongst Klebsiella pneumoniae isolates through plasmid mediated mcr-1 gene in Pakistan. Carbapenem and Colistin resistant K. pneumoniae isolates (n = 34) stored at - 80 °C as part of the Aga Khan University Clinical Laboratory strain bank were randomly selected and subjected to mcr-1 gene PCR. To investigate mechanisms of resistance, other than plasmid mediated mcr-1 gene, whole genome sequencing was performed on 8 clinical isolates, including 6 with colistin resistance (MIC > 4 µg/ml) and 2 with intermediate resistance to colistin (MIC > 2 µg/ml). RESULTS: RT-PCR conducted revealed absence of mcr-1 gene in all isolates tested. Whole genome sequencing results revealed modifications in Lipid A-Ara4N pathway. Modifications in Lipid A-Ara4N pathway were detected in ArnA_ DH/FT, UgdH, ArnC and ArnT genes. Mutation in ArnA_ DH/FT gene were detected in S3, S5, S6 and S7 isolates. UgdH gene modifications were found in all isolates except S3, mutations in ArnC were present in all except S1, S2 and S8 and ArnT were detected in all except S4 and S7. In the absence of known mutations linked with colistin resistance, lipid pathway modifications may possibly explain the phenotype resistance to colistin, but this needs further exploration.

Spectrum of Fungal Pathogens in Burn Wound Specimens: Data From a Tertiary Care Hospital Laboratory in Pakistan.

Burn patients are at great risk of developing fungal wound infections. Fungi are frequently cultured from burn tissue specimens alone or in combination with bacteria. However, the spectrum of fungi in burn patients from Pakistan has not been reported previously. A retrospective laboratory-based study was conducted and data on all positive cultures from burn wounds were included. During the study period, specimens were cultured on appropriate media and incubated for anaerobic and aerobic growth. Clinical and demographic information recorded during clinical reporting was also collected. Seventy tissue cultures were positive for microorganisms. Of these, 27 (39%) had growth of either filamentous mold (17 cases) or Candida species (14 cases). Two cases had growth of both mold and yeast. Aspergillus flavus was the most common mold (9) followed by Fusarium species (3). Candida tropicalis was the most common yeast (7) followed by Candida parapsilosis (4). There was concomitant bacterial growth in 19 cases, predominantly of Staphylococcus aureus (13), Pseudomonas aeruginosa (8), and other Gram-negative rods (6). Of the 35 patients in which treatment history was available, 33 were receiving broad-spectrum antibiotics. A high incidence of fungal isolation was seen in this study. Their findings are consistent with the global increase in fungal infections in burn wounds. High index of suspicion by clinicians and revision of culture protocols in burn patients may be warranted for optimal patient management.