Molecular Epidemiology and Mechanisms of Carbapenem-Resistant Acinetobacter baumannii Isolates from ICU and Respiratory Department Patients of a Chinese University Hospital

Figures & data

Table 1 Information Concerning the Primers Used in This Study

Primer Name	Sequence (5′→3′)	DNA Amplicon Size (bp)	Annealing Temperature (°C)	Reference
OXA-23-like	F: GATCGGATTGGAGAACCAGA R: ATTTCTGACCGCATTTCCAT	501	53.2	[^Citation23]
OXA-51-like	F:CTAATAATTGATCTACTCAAGTTAC R: GAATACTCCATTTGAACCARTGG	988	55.1	[^Citation24]
NDM	F: CGGAATGGCTCATCACGATC R: CGGAATGGCTCATCACGATC	621	50	[^Citation25]
IMP	F: GGAATAGAGTGGCTTAAYTCTC R: GGTTTAAYAAAACAACCACC	232	55	[^Citation25]
VIM	F: GATGGTGTTTGGTCGCATA R: CGAATGCGCAGCACCAG	390	55	[^Citation25]
KPC	F: CGTCTAGTTCTGCTGTCTTG R: CTTGTCATCCTTGTTAGGCG	798	55	[^Citation25]
ampC	F: AGGAGCTAATCATGCGATT R: CAAGCTTAGGATATGTTTGG	1259	56	[^Citation26]
CarO	F: GACAACTACAGCTTTACTTGCT R: ACACCAACTTTACCAACTGG	711	57	[^Citation23]
SPM	F:AAAATCTGGGTACGCAAACG R:ACATTATCCGCTGGAACAGG	271	52	[^Citation26]
AIM	F:CTGAAGGTGTACGGAAACAC R:GTTCGGCCACCTCGAATTG	322	52	[^Citation26]

Abbreviation: CarO, carbapenem-associated resistance OMP.

Table 2 Summarized Demographic Data for All Patients from Respiratory Department and ICU (n=60)

Parameter	Quantity Respiratory Department	Quantity ICU	P value
Age	60.36±15.52 (mean years old ±SD)	61.48±16.32 (mean years old ±SD)	0.88
Gender
Male	60%(18/30)	63.33%(19/30)	0.92
Female	40%(12/30)	36.67%(11/30)	0.76
Hospitalization days	19.38±13.25 (mean days ±SD)	21.55±18.87 (mean days ±SD)	0.62
Crude Mortality	30%(9/30)	40%(12/30)	0.59
Attributable mortality	6.67%(2/30)	23.33%(7/30)	0.15
Mechanical intervention
Intubation	53.33%(16/30)	70%(21/30)	0.28
Tracheostomy	16.67%(5/30)	30%(9/30)	0.36
Isolation source
Sputum	86.67%(26/30)	76.67%(23/30)	0.38
Blood	10%(3/30)	10%(3/30)	>0.99
Wounds	3.33%(1/30)	13.33%(4/30)	0.35
Urine	0%(0/30)	0%(0/30)
Acquired A. baumannii in hospital	100%(30/30)	100%(30/30)	>0.99
Median(range) APACHE II score	7.9 (2–20)	9.6 (1–24)	0.15
Median(range) Charlson score	1.75 (0–7)	1.11 (0–2)	0.24

Abbreviations: APACHE II, acute physiology and chronic health evaluation II score; SD, standard deviation; ICU, intensive care unit.

Table 3 Antimicrobial Resistance and Susceptibility Profiles of CRAB Clinical Isolates Obtained from Patients at Respiratory Department and ICU

Antimicrobial	All Isolates (n=60)										P value*
	MIC (μg/mL)		Range of Values		Breakpoint (Respiratory) Interpretations			Breakpoint (ICU) Interpretations
	MIC50	MIC90	Min	Max	%R	%I	%S	%R	%I	%S
Piperacillin/Tazobactam	4	64	≤1	>128	66.7(20)	0	33.3(10)	70(21)	0	30(9)	0.45
Cefoperazone/Sulbactam	4	64	≤1	>128	23.3(7)	10(3)	66.7(20)	53.3(16)	0	46.7(14)	0.03
Imipenem	0.5	8	≤0.03	>32	100(30)	0	0	100(30)	0	0	>0.99
Tigecycline	1	2	≤0.06	>16	0	0	100(30)	23.3(7)	0	76.7(23)	0.01
Colistin	1	2	≤0.06	>16	0	0	100(30)	0	0	100(30)	>0.99
Gentamicin	2	8	≤0.5	>32	46.7(14)	13.3(4)	40(12)	60(18)	10(3)	30(9)	0.25
Meropenem	0.5	8	≤0.03	>32	100(30)	0	0	100(30)	0	0	>0.99
Amikacin	4	16	≤1	>64	43.3(13)	13.3(4)	43.4(13)	53.3(16)	13.3(4)	33.7(10)	0.34
Ceftazidime	4	32	≤0.25	>32	53.3(16)	6.7(2)	40(12)	66.7(20)	10(3)	23.3(7)	0.19
Ciprofloxacin	0.25	4	≤0.06	>16	53.3(16)	0	46.7(14)	63.3(19)	0	36.7(11)	0.15

Notes: Breakpoint Interpretation: Amikacin S≤16μg/mL, I=32μg/mL, R≥64μg/mL, Ceftazidime S≤8μg/mL, I=16μg/mL, R≥32μg/mL, Ciprofloxacin S≤1μg/mL, I=2μg/mL, R≥4μg/mL, Colistin S≤2μg/mL, I=4μg/mL, R≥8μg/mL, Gentamicin S≤4μg/mL, I=8μg/mL, R≥16μg/mL, Meropenem S≤2μg/mL, I=4μg/mL, R≥8μg/mL, Piperacillin/Tazobactam S≤16/4μg/mL, I=32/4μg/mL, R≥128/4μg/mL, Cefoperazone/Sulbactam S≤16/4μg/mL, I=32/4μg/mL, R≥128/4μg/mL, Imipenem S≤2μg/mL, I=4μg/mL, R≥8μg/mL, Tigecycline S≤2μg/mL, I=4μg/mL, R≥8μg/mL. * represents result of comparison resistance rate between respiratory department and ICU.

Abbreviations: %S, susceptible; %I, intermediate; %R, %resistant.

Table 4 PCR Detection of Genes Associated with CRAB Isolates in Respiratory Department and ICU

Parameter	Respiratory Department(30) % (n)	ICU(30) % (n)	P value
Gene associated with carbapenem resistance
blaOXA-23	56.7 (17)	80.0 (24)	0.09
blaNDM-1	0 (0)	20 (6)	0.02
blaIMP-4	10 (3)	40 (12)	0.02
blaVIM-2	0 (0)	23.3 (7)	0.01
Mutation of CarO	60 (18)	86.7 (26)	0.04
ampC	13.3 (4)	16.7 (5)	>0.99

Abbreviation: carO, carbapenem-associated resistance OMP.

Figure 1 Detection of IMP genes of carbapenem-resistant Acinetobacter baumannii clinical isolates by PCR.

Figure 2 Detection of VIM genes of carbapenem-resistant Acinetobacter baumannii clinical isolates by PCR.

Figure 3 Detection of NDM genes of carbapenem-resistant Acinetobacter baumannii clinical isolates by PCR.

Figure 4 Dendrogram displaying the genetic relatedness of 60 CRAB strains, based on pulse field gel electrophoresis results.

Table 5 The MLST Results of CRAB in Respiratory Department and ICU

Respiratory Department (n=30)			ICU (n=30)
Type ST	% (n)	Number	Type ST	% (n)	Number
ST92	33.3 (10)	1, 4, 5, 9, 14, 17, 21, 22, 25, 28	ST92	63.3^※ (19)	31, 33,34,35,36,37, 39, 40, 44,45,47,48, 50, 51, 54, 55, 57, 59,60
ST175	20.0 (6)	2,7,11,16,23,27	ST111	20.0 (6)	12,32,38,46,53,58
ST298	13.3 (4)	8,41,24,26	ST244	10.0 (3)	13,49,56
ST773	6.7 (2)	42,30	ST357	6.7 (2)	43,52
ST111	6.7 (2)	3,15
ST316	6.7 (2)	18,19
ST639	3.3 (1)	6
ST991	3.3 (1)	29
ST2221	3.3 (1)	10
ST1015	3.3 (1)	20

Note: ^※Represents ICU VS respiratory department, P=0.03.

Mirshekar M, Shahcheraghi F, Azizi O, Solgi H, Badmasti F. Diversity of class 1 integrons, and disruption of carO and dacD by insertion sequences among Acinetobacter baumannii Isolates in Tehran, Iran. Microb Drug Resist. 2018;24(4):359–366. doi:10.1089/mdr.2017.015228972863

 PubMed Web of Science ®Google Scholar

Piran A, Shahcheraghi F, Solgi H, Rohani M, Badmasti F. A reliable combination method to identification and typing of epidemic and endemic clones among clinical isolates of Acinetobacter baumannii. Infect Genet Evol. 2017;54:501–507. doi:10.1016/j.meegid.2017.08.01828827174

 PubMed Web of Science ®Google Scholar

El-Shazly S, Dashti A, Vali L, Bolaris M, Ibrahim AS. Molecular epidemiology and characterization of multiple drug-resistant (MDR) clinical isolates of Acinetobacter baumannii. Int J Infect Dis. 2015;41:42–49. doi:10.1016/j.ijid.2015.10.01626518066

 PubMed Web of Science ®Google Scholar

Sun F, Ou Q, Wang Q, et al. The resistance and transmission mechanism of Acinetobacter baumannii isolates in a tertiary care hospital, China. J Chemother. 2016;28(6):476‐481. doi:10.1080/1120009X.2016.1139335

 Web of Science ®Google Scholar