Table 2.
Studies that considered phenotypic methods for detecting carbapenemase enzymes
| Author (year) | Setting | Population | Samples | Microorganism (no.) | MICa | Method of carbapenemase detection | Resistance to FQ and AG | Resultsb | Weak points | Strength points |
|---|---|---|---|---|---|---|---|---|---|---|
|
| ||||||||||
| Ghotaslou et al (2018)26 | Five hospitals in East and West Azerbaijan | General inpatients | Different sites | Enterobacteriaceae (307) | – | • DD • BA and DPA for MBL detection |
c | • Resistance rate to carbapenem was observed only in K. pneumonia (57 isolates; 25%–45%) • Of these 57 isolates, phenotypic methods revealed that 15%, 7%, and 3% isolates of Klebsiella had MBL, KPC, and OXA-48 genes, respectively • Most of the carbapenemase strains were isolated from urine and blood |
• Small sample size for each species | – |
| Saadatian Farivar et al (2018)27 | Three hospitals in Tehran | Inpatients and outpatients | Different sites | Klebsiella pneumonia (81) | – | • DD • MHT for MBL detection |
OFX 65%, CIP 68%, NOR 66%, GEN 66%, AMK 51%, TOB 56 %, KAN 79%, GEN 96% | • Resistance rate to IPM was 45% • 6 (7.4% of all) isolates were positive for MHT test |
– | – |
| Moosavian et al (2014)28 | Two hospitals in Ahvaz | General inpatients | Different sites | Acinetobacter spp. (100) | – | • DD • MHT |
AMK 96% CIP 98% | • Resistance rates to IPM, MEM, and ERT were 95%, 96%, and 53%, respectively • 53% of all strains were MHT positive |
– | – |
| Jonaidi Jafari et al (2014)29 | One hospital in Tehran | General inpatients | Different sites | Different strains (350) | ✓ | • DD • CDT for ESBL detection |
– | • MIC was determined by E-test • 95 strains were ESBLs • Resistance rates to IPM and MEM according to MIC, respectively, were: Acinetobacter baumannii 42%, 37% Pseudomonas aeruginosa 42%, 60% K. pneumonia 15%, 0% |
• Small sample size for each microorganism | – |
| Ghadiri et al (2014)30 | Three laboratories in Tehran | General outpatients | Urine | Escherichia coli (300) | • DD • CDT for ESBL detection • DDST for MBL detection |
AMK 11% GEN 16% |
• 67 isolates were ESBL producers and resistance to carbapenem in this group was about 10% • 21 isolates were MBL producers and resistance to carbapenems among them was almost 100% • 5 isolates were both MBL and ESBL positive |
– | • Large sample size | |
| Fazeli et al (2014)31 | Teaching hospitals in Isfahan | General inpatients and ICU patients | Different sites | K. pneumonia (142) | – | • DD • CDT for ESBL |
Resistance rate to GEN and AMK and CIP: 70%–80% LVX: 50%–60% | • Resistance rates to IPM, MEM, and ERT among all strains were 57%, 52%, and 47%, respectively • 101 strains were ESBL producers • Most of the ESBL producers were isolated from ICU and from urine samples |
• It is not clear that the study was multicenter or not | – |
| Mirsalehian et al (2014)32 | Motahari hospital | Burn patients | Probably burn wounds | P. aeruginosa (100) | ✓ | • DD • AmpC disk and CDT for AmpC production |
– | • All IPM-resistant Pseudomonas were chosen and mean MIC for IPM was 64 mcg/mL • AmpC disk test and CDT were positive for 54 and 17 isolates, respectively showing a probable activation of one of the efflux pump and impermeability systems, or both |
– | – |
| Moayednia et al (2014)33 | One hospital in Isfahan | General inpatients and outpatients | Urine | K. pneumonia (484) and E. coli (1,080) | • DD • Double Disk for ESBL • MHT for KPC detection • CDT for MBL detection |
Just reported for ESBL producer | • Resistance rate to carbapenem for E. coli was 1%–2% and for Klebsiella spp., it was 41%–46% • 390 isolates of E. coli and 238 Klebsiella were ESBL producers • From all of strains: E. coli: 2 MBL and 10 KPC producers Klebsiella spp.: 10 MBL and 186 KPC producers |
• MIC was done by E-test, but cutoffs were not reported | • Large sample size | |
| Erfani et al (2013)34 | Three hospitals in Tehran | General inpatients | Different sites | Acinetobacter sp. (107) | – | • DD • CDT for MBL detection |
CIP 95% LVX 93% GEN 51% TOB 64% |
• Resistance rate to IPM and MEM was about 95% and 92% of these resistant isolates were MBL positive | – | – |
| Lari et al (2013)24 | One hospital in Tehran (Motahhari) | Burn patients | Mostly burn wound | Acinetobacter spp. (69) | – | • SDDT for ESBL detection • CDT for MBL detection |
GEN 64.7% AMK 95.7% KAN 97.1% TOB 2.9% CIP 97.1% |
• Resistance rate to IPM was 92% • ESBL was positive in 10% of isolates • 24% of all baumannii isolates were MBL positive • The mortality rate in this study was 20% |
– | • Mortality rate was reported • Detection of Integron genes |
| Rastegar Lari et al (2013)25 | One hospital in Tehran (Motahari) | Burn patients | Burn wounds | Klebsiella spp. (35) | – | • DD • MHT for KPC production |
AMK 71% GEN 72% TOB 86% |
• Resistance rate to IPM was 54% and all were KPC producers • 7 out of 28 patients had two Klebsiella isolates with two different antibiotypes • Rate of mortality in patients infected with resistant strain was 33% |
• FQ and colistin were not tested • MIC values were not reported • Small sample size |
• Mortality rate was reported |
| Safari et al (2013)35 | Three educational hospitals in Hamadan | ICU patients | Trachea, blood, urine, sputum, wounds | A. baumannii (100) | ✓ | • DD • E-test for MBL |
Resistant: CIP 97% LVX 91% AMK 84% GEN 88% |
• Resistance rate to carbapenem was 85%–94% but according to MIC, it was 87%–99% • 99% of all isolates were MBL producers |
• Multicenter study • MIC was reported |
|
| Masaeli et al (2012)36 | Two hospitals in Sanandaj | General inpatients | Different sites | Different strains (423) | – | • DD • DDST for MBL detection |
GEN 70% AMK 80% CIP 37% NOR 42% |
• The result of disk diffusion for carbapenem was not reported • 126 isolates (30% of all) were MBL positive • Risk factors like immunosuppression and use of antibiotics during the past 2 weeks were correlated with infection by MBL producers |
• The resistance pattern of each group of microorganisms was not fully defined | • Correlation between being MBL and different clinical risk factors was assessed |
| Japoni-Nejad et al (2013)37 | One hospital in Arak | General inpatients and environmental isolates | Different strains | A. baumannii (63) | ✓ | • MHT for KPC detection • E-test |
Amikacin 80% Netilmicin 54% |
• 84% were resistant to carbapenem • 47 isolates were MBL producers according to E-test and three of them were MHT positive • 60 strains had MIC more than 256 |
• Isolates from environment of hospital were also included | • Small sample size |
| Haji Hashemi et al (2012)39 | Different hospitals in Tehran and Isfahan | General inpatients and outpatients | Different sites | Klebsiella pneumoniae (244) | – | • DD • MHT for KPC detection • CHROMagar for KPC detection |
– | • MHT and CHROMagar were compared • From all, 30 and 36 isolates were KPC producers according to MHT and CHROMagar, respectively. The infection of burn wounds at the highest percentage: 27 cases (75 %) |
• MIC was not reported | • Multicenter study |
| Azimi et al (2012)40 | Two burn hospitals in Tehran | Infant and pediatric patients | Not defined (probably burn wounds) | Klebsiella, Acinetobacter, and Pseudomonas (64 strains from 20 patients) | – | • DD • MHT for KPC production • CDT for ESBL detection |
Not defined | • 36 isolates were resistant to all tested antibiotic (not mentioned which antibiotics) except Colistin • Among these 36 isolates, 15 isolates were resistant to IPM • From these 15 isolates, 13 were KPC and 6 were ESBL producers |
• Types of samples were not defined • The sample size is very small (7 A. baumannii, 16 Enterobacteriaceae, 12 Pseudomonas) • There is no precise data of resistance to each antibiotic |
|
| Japoni et al (2006)41 | One hospital in Shiraz | General inpatients | Different sites (mostly wound) | P. aeruginosa (70) | ✓ | • DD • DDST for ESBL • MHT for MBL detection |
CIP 73% AMK 93% TOB 97% |
• Resistance rate to carbapenems was 33% • MIC value for IPM was 2 and for MEM was 1 • MBL was not detected |
• Small sample size | |
Notes:
a
MIC values for carbapenems (but not other antimicrobial agents) were determined.
b
Resistance rates were according to the result of disk diffusion test.
c
For complete information about the resistance to AG and FQ, please refer to the original reference.
Abbreviations: AG, aminoglycoside; AMK, amikacin; BA, boronic acid; CDT, combination disk test; CIP, ciprofloxacin; DD, disk diffusion; DDST, double disk synergy test; DOR, doripenem; DPA, dipicolinic acid; ERT, ertapenem; ESBL, extended spectrum β-lactamase; FQ, fluoroquinolones; GEN, gentamicin; ICU, intensive care unit; IPM, imipenem; KAN, kanamycin; KPC, Klebsiella-producing carbapenemase; LVX, levofloxacin; MBL, metallo-β-lactamase; MEM, meropenem; MHT, modified Hodge test; MIC, minimum inhibitory concentration; NAL, nalidixic acid; NOR, norfloxacin; OFX, ofloxacin; TOB, tobramycin.