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Letter
Beijing/W Mycobacterium
tuberculosis in Italy
Nicoletta Lari,* Laura Rindi,* Daniela Bonanni,* Enrico Tortoli,†
and Carlo Garzelli*
*Università di Pisa, Pisa, Italy; and †Ospedale Careggi, Firenze, Italy
Suggested citation
for this article:
Lari N, Rindi L, Bonanni D, Tortoli E, Garzelli C. Beijing/W Mycobacterium
tuberculosis in Italy. Emerg Infect Dis [serial on the Internet]
2004 May [date cited]. Available from: http://www.cdc.gov/ncidod/EID/vol10no5/03-1024.htm
To the Editor: Molecular typing of Mycobacterium tuberculosis
strains isolated in several countries in recent years has shown that a
group of strains known as "Beijing" is widespread around the
world (1). The Beijing group of M. tuberculosis
has been associated with drug resistance; one multidrug-resistant strain,
designated "W," was found in New York City in the early 1990s
and caused large institutional outbreaks of tuberculosis (TB) in the United
States (2). M. tuberculosis strains of Beijing/W
genotype are mostly prevalent in Asia (1), but recent
data suggest that they have been spreading in Indochina and are prevalent
among younger persons in Vietnam (3). Beijing/W strains
are also widespread in Eastern Europe (1); during the
last decade, the Beijing/W genotype of M. tuberculosis, with more
prevalent drug-resistant mutations than non-Beijing strains, has been
identified in 40% to 50% of clinical isolates studied in Russia (4).
We studied a total of 245 M. tuberculosis strains collected during
a 1-year period, from January to December 2002, from the same number of
TB patients hospitalized in Tuscany, Italy. All the isolates were typed
by the standardized IS6110 restriction fragment length polymorphism
(RFLP) and the spoligotyping (spacer oligonucleotide typing) techniques.
A total of 216 distinct IS6110 RFLP patterns were found among the
245 isolates; 51 isolates (20.8%) occurred in 23 clusters, each constituting
strains with an identical IS6110 RFLP and spoligotype pattern;
19 clusters contained two isolates each, 3 contained three isolates, and
1 contained four isolates. Spoligotype analysis showed seven isolates
with the typical Beijing/W pattern of probe hybridization only to spacer
sequences 35–43. The Beijing/W isolates yielded distinct IS6110
RFLP profiles with similarity coefficient >57.8%. Characteristics of
the Beijing/W strains and respective patients, obtained from clinical
records, are reported in the Table. Although the overall prevalence of
Beijing/W strains was low (7/245, 2.9%), five of the seven strains were
from recent immigrants to Italy from China who live in the same area;
the other two strains were from Italian citizens also living in that area.
Recent immigration from high-prevalence areas is therefore likely to be
associated with the occurrence of the Beijing/W genotype in Italy. None
of the Beijing/W strains was associated with TB outbreaks; nonetheless,
infection of Italian residents with Beijing strains suggests that spread
of this genotype is ongoing.
Beijing/W strains have been strongly associated with drug resistance
in a number of countries (2,4–6), but elsewhere the association
was weak or absent. In our survey, no substantial drug resistance was
observed; all Beijing/W strains isolated in Tuscany were susceptible to
rifampin, ethambutol, pirazinamide, and streptomycin (tested only in two
strains), and all but one were susceptible to isoniazid.
Although we detected only a few cases, our data do not show a trend of
Beijing/W strains' being associated with infection in young people, as
has been observed in other settings (3). The age of immigrants
with Beijing/W TB (mean 33.2 years, standard deviation [SD] 8.2 years)
did not significantly differ from that of immigrants infected with non-Beijing/W
strains (30.7 years, SD 7.4 years), a find that indicates that, at least
in our setting, immigrant status, rather than M. tuberculosis genotype,
is associated with infection in young people. The few cases of Beijing/W
infections in Italian-born patients do not allow us to draw conclusions
regarding nonimmigrant patients.
In conclusion, M. tuberculosis strains of Beijing/W genotype are
becoming widespread worldwide, including in countries with a low prevalence
of TB. Their association with drug resistance and infection in young people,
clearly shown in certain settings, remains to be defined. Further molecular
epidemiologic surveillance is needed to monitor trends in prevalence and
spread of these strains.
This work was supported
by National Research Program on AIDS grant no. 50D.11 from the Istituto
Superiore di Sanità, Rome, Italy.
References
- Glynn JR, Whiteley J, Bifani PJ, Kremer K, van Soolingen
D. Worldwide
occurrence of Beijing/W strains of Mycobacterium tuberculosis:
a systematic review. Emerg Infect Dis 2002;8:843–9.
- Bifani PJ, Mathema B, Liu Z, Moghazeh SL, Shopsin B, Tempalski B,
et al. Identification
of a W variant outbreak of Mycobacterium tuberculosis via population-based
molecular epidemiology. JAMA 1999;282:2321–7.
- Anh DD, Borgdorff MW, Van LN, Lan NT, van Gorkom T, Kremer K, et al.
Mycobacterium
tuberculosis Beijing genotype emerging in Vietnam. Emerg Infect
Dis 2000;6:302–5.
- Mokrousov I, Otten T, Vyazovaya A, Limeschenko E, Filipenko ML, Sola
C, et al. PCR-based
methodology for detecting multidrug-resistant strains of Mycobacterium
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- Diaz R, Kremer K, de Haas PE, Gomez RI, Marrero A, Valdivia JA, et
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SB, et al. Spread
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| Table.
Characteristics of Mycobacterium tuberculosis strains of Beijing/W
genotype isolated in 2002 in Tuscany, Italya |
|
|
Strain no.
|
Patient's country of birth
|
Sex
|
Age
|
HIV status
|
Years in Italy
|
Site of TB
|
Drug resistanceb
|
|
|
Str
|
Inh
|
Rif
|
Eth
|
Pza
|
|
|
669
|
China
|
M
|
40
|
–
|
1
|
Pulmonary
|
S
|
S
|
S
|
S
|
S
|
|
763
|
China
|
M
|
42
|
–
|
<1
|
Pulmonary
|
S
|
S
|
S
|
S
|
S
|
|
804
|
China
|
F
|
23
|
–
|
4
|
Pulmonary
|
NT
|
S
|
S
|
S
|
S
|
|
836
|
China
|
M
|
34
|
–
|
1
|
Pulmonary
|
NT
|
S
|
S
|
S
|
S
|
|
884
|
Italy
|
F
|
39
|
+
|
NA
|
Extrapulmonary
|
NT
|
S
|
S
|
S
|
S
|
|
952
|
Italy
|
F
|
28
|
–
|
NA
|
Pulmonary
|
NT
|
R
|
S
|
S
|
S
|
|
974
|
China
|
F
|
27
|
–
|
1
|
Pulmonary
|
NT
|
S
|
S
|
S
|
S
|
|
| aTB, tuberculosis;
Str, streptomycin; Inh, isoniazid; Rif, rifampin; Eth, ethambutol;
Pza, pirazinamide; S, susceptible; R, resistant; M, male; F, female;
NA, not applicable; NT, not tested. |
| bDrug resistance
was assessed by the radiometric BACTEC system (Becton Dickinson, Towson,
MD) according to the proportion method. |
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