Mycobacterium chimaera infections following cardiac surgery in Treviso Hospital, Italy, from 2016 to 2019: Cases report

Table 1 Clinical features and outcome

Case	sex/age	Cardiac surgery	Date surgery	Symptoms beginning	Date hospitali-zation	Micro-biological diagnosis (date) and disease history	Clinical syndromes	Medical therapy (mo)	Repeat surgery and disease history	Outcome
1	M 37	CARR	12/2012 TH	After 35 mo	05/2016	09/2016, after 10 mo	PVE, AAP, DI	Anti-MAC (1)	After 8 mo	Deceased
2	M 60	AVR + MVA	01/2013 oH	After 40 mo	05/2016	10/2016, after 11 mo	PVE, AAP, DI	No	No (see text)	Deceased
3	M 42	AVR + ARR	05/2015 TH	After 6 mo	10/2016	11/2016, after 12 mo	PVE, AAP, DI	No	No	Deceased
4	M 75	AVR	02/2011 TH	After 64 mo	07/2016	01/2017, after 7 mo	PVE, DI, SD	Anti-MAC (13)	After 15 mo	Deceased
5	M 80	MVR + AW	03/2016 TH	After 12 mo	08/2018	09/2018, after 18 mo	PVE, SD	Targeted (14)	No	On therapy
6	M 56	AVR	06/2016 TH	After 27 mo	11/2018	10/2018, after 1 mo	PVE, DI, SD	Targeted (12)	After 8 mo	On therapy
		ARR	05/2015 TH
7	M 75	AVR	01/2014 oH	After 21 mo	02/2019	04/2019, after 8 months	PVE	Targeted (4)	No	On therapy
		AVR	11/2016 oH
8	M 76	AVR + CABG	02/2011 TH	After 97 mo	05/2019	05/2019, after 2 mo	PVE, DI, SD	Targeted (3)	No	On therapy
9	M 82	AVR + CABG	08/2016 oH	After 12 mo	06/2019	06/2019, after 22 mo	PVE	Targeted (2)	No	On therapy

AAP: Ascending aortic pseudoaneurysm; ARR: Aortic root replacement; AVR: Aortic valve replacement; AW: Ascending aortic wrapping; CABG: Coronary artery bypass graft; cARR: Composite aortic root replacement; DI: Disseminated infection; MVA: Mitral valve annuloplasty; oH: Other hospital; PVE: Prosthetic valve endocarditis; SD: Spondylodiscitis; TH: Treviso Hospital; MAC: Mycobacterium avium complex.

Table 2 Clinical features of Mycobacterium chimaera infections and selected laboratory abnormalities of Mycobacterium chimaera infected patients at presentation in United Kingdom and Treviso patients (modified, from Scriven et al[16], 2018)

Variable	UK patients (n = 30)	Italian patients (n = 9)
Clinical finding, n (%)
Fever	24 (80)	7 (78)
Malaise (astenia)	24 (80)	7 (78)
Weight loss	18 (60)	6 (66)
Cough	11 (37)	3 (33)
Dyspnoea	10 (33)	2 (22)
Arthralgia	6 (20)	0
Chest pain	6 (20)	0
Abdominal pain	3 (10)	0
Back pain	2 (7)	5 (55)
New cardiac murmur	9 (30)	6 (66)
Oedema	6 (20)	1 (11)
Crepitations	6 (20)	0
Splenomegaly	8 (27)	6 (66)
Hepatomegaly	6 (20)	3 (33)
Lymphadenopathy	1 (3)	1 (11)
Sternal wound	4 (13)	0
Skin lesion	2 (7)	0
Choroiditis	2 (7)	5 (55)
Neurological symptoms	NA	5 (55)
Laboratory findings, median (IQR)
Haemoglobin (g/L)	110 (96-127)	105 (95-114)
WBC (× 109/L)	3.9 (2.2-5.4)	3.9 (2.8-6.7)
Neutrophils (× 109/L)	2.4 (1.3-3.3)	2.6 (1.4-3.8)
Lymphocytes (× 109/L)	0.9 (0.6-1.3)	0.76 (0.56–1.05)
Platelets (× 109/L)	175 (86-223)	166 (76-257)
Albumin (g/L)	30 (26-37)	34 (27-39)
ALT (IU/L)	43 (33-85)	41 (15-70)
ALP (IU/L)	256 (132-357)	242 (157-254)
Sodium (µmol/L)	134 (131-136)	131 (128-136)
eGFR (mL/min)	66 (53-80)	52 (35-81)
CRP (mg/L)	33 (17-46)	19 (14-31)
ESR (mm/h)	NA	65 (36-111)
LDH (IU/L)	NA	463 (244-680)
gammaGT (IU/L)	NA	104 (44-156)

ALP: Alkaline phosphatase; ALT: Alanine transaminase; CRP: C-reactive protein; eGFR: Estimated glomerular filtration rate; ESR: Erythrocyte sedimentation rate; gammaGT: Gammaglutamiltranspeptidase; IQR: Interquartile range; LDH: Lactate dehydrogenase; NA: Not available; WBC: White blood count.

Table 3 Microbiological features

Case	Specimens	Time for cultural identification	Other positive tests	Antimicrobial susceptibility test
11	Sputum	8 wk		Macrolid (S)2
	Broncholavage	10 wk
	Bioprosthesis	np	PCR
	Pericardial abscess	8 wk
	Blood	np
2	Blood	4 wk		Macrolid (S)2
3	Blood	4 wk		Macrolid (S)2
4	Blood (2)	3 wk		Clarithromycin (S); Linezolid (R); Moxifloxacin (S); Aminoglycoside (S)2; Macrolid (S)2
	Bioprosthesis	6 wk	Microscopy after enrichment
	Vertebral bone	12 wk
5	Vertebral bone (3)	3, 5, and 10 wk	Auramine rhodamine stain	Clarithromycin (S); Linezolid (I); Moxifloxacin (R)
	Blood (2)	Negative
6	Blood (3)	3, 4, and 5 wk		Clarithromycin (S); Linezolid (I); Moxifloxacin (R)
	Bone Marrow	2 wk	Microscopy after enrichment
	Bioprosthesis (5)	3 wk	Microscopy after enrichment
7	Blood	6 wk		Clarithromycin (S); Linezolid (I); Moxifloxacin (S)
8	Blood (2)	4 wk		Clarithromycin (S); Linezolid (S); Moxifloxacin (S)
9	Blood	4 wk		ip

¹Originally identified as M. intracellulare;

²Molecular Characterization. ip: In process; np: Not performed; S: Susceptible; I: Intermediate; R: Resistant.

Table 4 Measures taken to mitigate the risk of Mycobacterium chimaera infections after cardiac surgery in Veneto region

	Measures
Environmental control measures	Mycrobiological surveillance of HCUs and operating room
	Culture-negative HCUs: carry out maintenance and cleaning of the device according to the manufacturer's recommendations
	Culture-positive HCUs: remove the HCU from the operating room and/or send the device to the manufacturer for sterilization and cleaning
Clinical control measures	Enhance active case finding
	Alert clinicians for passive case findings
	Notify the confirmed or probable cases

HUC: Heater-cooler unit.