TABLE 6.

ESBL detection techniques

Technique type	Test	Advantages	Disadvantages	Reference(s)
Clinical microbiology	Standard NCCLS interpretive criteria	Easy to use, performed in every lab	ESBLs not always “resistant”	78, 111
	NCCLS ESBL confirmatory test	Easy to use and interpret	Sensitivity depends on choice of oxyimino-cephalosporin	111
	Double-disk approximation test	Easy to use, easy to interpret	Distance of disk placement for optimal sensitivity not standardized	76, 169, 71
	Three-dimensional test	Sensitive, easy to interpret	Not specific for ESBLS, labor intensive	169
	Etest ESBL strips	Easy to use	Not always easy to interpret, not as sensitive as double-disk test	183
	Vitek ESBL test	Easy to use, easy to interpret	Reduced sensitivity	149, 164
Molecular detection	DNA probes	Specific for gene family (e.g., TEM or SHV)	Labor intensive, cannot distinguish between ESBLs and non-ESBLs, cannot distinguish between variants of TEM or SHV	7, 55, 70
	PCR	Easy to perform, specific for gene family (e.g., TEM or SHV)	Cannot distinguish between ESBLs and non-ESBLs, cannot distinguish between variants of TEM or SHV	42, 90, 116
	Oligotyping	Detects specific TEM variants	Requires specific oligonucleotide probes, labor intensive, cannot detect new variants	117
	PCR-RFLP	Easy to perform, can detect specific nucleotide changes	Nucleotide changes must result in altered restriction site for detection	116
	PCR-SSCP	Can distinguish between a number of SHV variants	Requires special electrophoresis conditions	106, 107
	LCR	Can distinguish between a number of SHV variants	Requires a large number of oligonucleotide primers	80
	Nucleotide sequencing	The gold standard, can detect all variants	Labor intensive, can be technically challenging, can be difficult to interpret manual methods	25