Table 2.
Categorization of Likelihood of Transmission From Index Case to Household Contacts in 16 Households With Carbapenemase-Producing Enterobacterales–Colonized Household Contacts
| Transmission Category | HC Risk Factors | IC/HC Species and ST | IC/HC Carbapenemase | Description of Relatedness Between IC and HC Pairs of Isolates/Carbapenemase Gene–Containing Plasmids |
|---|---|---|---|---|
| Confirmed (n = 3) | None | Escherichia coli ST405 | NDM-5 | Highly related isolates (1 SNV) |
| E. coli ST167 | NDM-5 | Highly related blaNDM-5–containing plasmidsa in related isolates (20 SNVs) | ||
| E. coli ST359 | NDM-7 | Highly related blaNDM-7–containing plasmidsa in related isolates (54 SNVs) | ||
| Probable (n = 2) | None | E. coli (IC), culture-negative (HC) | NDM | NA (HC PCR-positive but culture-negative) |
| High-risk co-travel with ICb | Klebsiella pneumoniae ST410 | NDM-1 | Highly related isolates (6 SNVs) | |
| Possible (n = 9) | High-risk co-travel with ICc | E. coli ST372 | OXA-181 | Highly related isolates (0 SNVs) |
| E. coli ST410 | NDM-5 | Highly related isolates (4 SNVs) | ||
| E. coli ST405 | NDM-5 | Highly related isolates (9 SNVs) | ||
| K. pneumoniae ST307 | NDM-5 | Highly related blaNDM-5–containing plasmidsa in related isolates (19 SNVs) | ||
| E. coli ST8655 (IC) and ST940 (HC) | OXA-181 | Highly related blaOXA-181–containing plasmidsa in unrelated isolates (>25 000 SNVs) | ||
| E. coli ST410 (IC) and ST372 (HC) | OXA-181 | Highly related blaOXA-181–containing plasmidsa in unrelated isolates (>25 000 SNVs) | ||
| E. coli ST405 (IC) and ST457 (HC) | NDM-5 | Highly related blaNDM-5–containing plasmidsa in unrelated isolates (>25 000 SNVs) | ||
| E. coli (IC), culture-negative (HC) | OXA | NA (HC PCR positive but culture negative) | ||
| E. coli (IC), isolate unavailable (HC) | NDM | NA (HC isolate unavailable) | ||
| Unlikely (n = 2) | High-risk travel | K. pneumoniae ST14 (IC), E. coli ST8131(HC) | OXA-232 (IC), OXA-181 (HC) | Unrelated plasmidsa |
| K. pneumoniae ST15 (IC), Enterobacter cloacae ST171 (HC) | NDM-1 | Unrelated plasmidsa |
Abbreviations: CPE, carbapenemase-producing Enterobacterales; HC, household contact; IC, index case; NA, not applicable; PCR, polymerase chain reaction; SNV, single nucleotide variant; ST, sequence type.
aSee Supplementary Table 2.
bHC colonization was detected after 4 negative screens post–co-travel with the IC.
cHC colonization was detected after 0 to 2 negative screens post–co-travel with the IC.