Mycobacteria in water, soil, plants and air: a review

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Mycobacteria in water, soil, plants and air: a review

K. Hruska, M. Kaevska

Veterinary Research Institute, Brno, Czech Republic

ABSTRACT: Amazingly, despite the 24 143 papers on mycobacteria, indexed in the Web of Science database during the last six years, published by 67 008 authors from 13 128 organizations located in 166 countries or territories, interna-tionally accepted legal directives on how to control the public health risk associated with environmental mycobacteria have yet to be developed. Mycobacteria are human and animal pathogens, causing not only tuberculosis and leprosy, but mycobacterioses of skin, soft tissues and lung. Due to their cell wall composition and their adaptability mycobac-teria can survive in different habitats for years. Their immunomodulatory ability has been recognised for more than 50 years and hundreds of papers published during the last two decades have demonstrated that small chemical products derived from mycobacterial cells participate in inflammatory pathways involved the pathogenesis of important human diseases like Crohn’s disease, asthma, type 1 diabetes mellitus, psoriasis, arthrosis, Blau syndrom, sarcoidosis, autism etc. Mycobacteria can influence inflammatory pathways not only as live organisms, but also by means of components derived from dead cells. Pasteurisation or cooking does not affect this ability. Hence, how many mycobacterial cells are ingested, what factors play a role concurrently, and how long the harmful effect persists become important questions. This paper presents only a short review based on selected papers about mycobacteria in water, soil, plants and air with the aim of attracting attention to this significant global problem and of making the first steps towards protection of people. Selected bibliographic references of published data from 2007 to 2012 are presented in easy-to-navigate tables.

Keywords: Mycobacterium; water; soil; plant; vegetables; air; biofilm; sediment; determination; zoonoses; food safety

List of abbreviations

CFU = colony forming units; DGGE = denaturation gradient gel electrophoresis; IMS = immuno-magnetic separation;

IS = insertion sequence; ITS = intergenic transcribed spacer; MAC = Mycobacterium avium complex; MAP/Map=

Mycobacterium avium subsp. paratuberculosis; MTC = Mycobacterium tuberculosis complex; MWF = metal working

fluids; nPCR = nested PCR; NTM = non-tuberculous mycobacteria; PCR = polymerase chain reaction; PPM = poten-tially pathogenic mycobacteria; qPCR = quantitative real time PCR; RFLP = restriction fragment length polymorphism

Tables

Table 1. Search profiles used and numbers

of results retrieved

Table 2. Selected review articles

Table 3. Mycobacteria in water

Table 4. Mycobacteria in soil

Table 5. Mycobacteria in plants

Table 6. Mycobacteria in air

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1. Introduction

Potentially pathogenic mycobacteria, also

re-ferred to as non-tuberculous mycobacteria, are

known pathogens of animals and can cause diseases

also in humans, especially in immunocompromised

persons. Mycobacterioses differ depending upon

the species and hosts involved and upon ways of

in-fection, and may present as pulmonary, skin or soft

tissue lesions (Wagner and Young 2004; Griffith

et al. 2007; Jarzembowski and Young 2008). Some

hosts can develop a generalised mycobacteriosis.

The immunomodulatory potential of mycobacteria

is in the spotlight as a consequence of the

compo-sition of the mycobacterial cell wall. Bacterial cell

wall components have a high immunomodulatory

potential. Dead mycobacteria have been used in the

complete Freund adjuvans for more than 50 years.

Muramyldipeptides were discovered as the

mini-mal structures responsible for the improved

reac-tion to antigens (Ellouz et al. 1974; Traub et al.

2006; Coulombe et al. 2009). This ability has been

proven by experiments which showed that

syn-thetic molecules have the same effects. Coulombe

et al. (2009) reported that

N

-glycolyl MDP has a

greater NOD2-stimulating activity than

N

-acetyl

MDP, consistent with the historical observation

attributing exceptional immunogenic activity to

mycobacterial cells.

N

-glycolyl MDP is produced

by degradation of mycobacterial peptidoglycans.

The importance of a lipid antigen in the

molecu-lar pathogenesis of ruminant paratuberculosis and

human inflammatory bowel diseases are subjects

of recently published data (Momotani et al. 2012;

Mori and De Libero 2012). It is evident that under

specific conditions mycobacteria can be zoonotic

or environmental pathogens for humans and an

agents that participate in foodborne autoimmune

or autoinflammatory human diseases. Crohn’s

disease, type 1 diabetes mellitus, psoriasis,

mul-tiple sclerosis, asthma, arthrosis, autism, Blau

syndrome and sarcoidosis are the most frequently

mentioned diseases with respect to bacterial

trig-gers. Nevertheless, mycobacteria are not unique

in their ability to act as bacterial triggers. Some

known pathogens are possible sources of

compo-nents that trigger inflammatory processes as a

con-sequence of their intensive replication during the

primary infection. Non-tuberculous mycobacteria

were not a focus of interest for a long time because

their participation in pathogenesis need not follow

the Koch’s postulates completely or unequivocally.

Those who cannot accept the term “pathogen” for

cells unable to replicate can describe the harmful

microorganism as an immunomodulator, bacterial

trigger or allergen-like factor.

The difficult diagnosis by culture of slow or

non-growing mycobacteria has also contributed

to an underestimation of mycobacteria as a public

health risk. However, the current understanding

of the molecular pathogenesis of autoimmune or

allergic diseases, the recognition of genetic or

epi-genetic components in the pathogenesis of many

diseases, the expanding use of molecular

biol-ogy in research on mycobacteria, and the rapidly

growing number of publications and data on the

distribution of mycobacteria in the environment,

namely in water, air and soil, have all

contrib-uted to the evolution of a new understanding of

the role of mycobacteria.

Mycobacterium avium

subsp.

paratuberculosis

plays an important role in

this paradigm. Paratuberculosis (Johne’s disease)

in cattle and sheep was for a long time considered

unimportant both for animal breeding and food

safety and remained uncontrolled with regard to

milk and meat contamination and in animal trade

and mobility. Thus, the herd incidence increased in

countries with intensive cattle and sheep industry

enormously, up to an estimated 70% to 90% of all

herds. The infectious agent is very resistant, can

survive for a long time in water and liquid dung and

can survive and replicate in amoebae. The number

of mycobacteria in faeces can reach 10

8

per gram,

in milk and meat 10

4

per gram and in water 10

4

per

ml. It is therefore evident that humans are not

abso-lutely protected against exposure to mycobacteria

and their components. The important factors in

this exposure are the numbers of mycobacteria and

the age and dispositions of the hosts. Obviously

some sensitisation can occur inapparently and an

interval of many years can exist between the first

contact and development of the clinical form of

disease. The unknown sources of mycobacteria

and the creeping development of health problems

make the understanding of possible consequences

rather difficult.

The risk of direct transmission of live tuberculous

mycobacteria between humans or animals takes the

form of droplet infection in open forms of

pulmo-nary tuberculosis (

M. tuberculosis

,

M. bovis

and

M. caprae

). The risk of contracting human

(3)

intercon-tinental flight. Non-tuberculous mycobacteria can

be transmitted in raw milk or insufficiently

heat-treated meat. Water and soil are frequent sources

of mycobacterial infections either in the form of

direct contacts for aquarists or gardeners or by

means of aerosols in showers or indoor swimming

pools. Water in hospitals and dental units or metal

working fluids (Falkinham 1996, 2009a,b; Primm et

al. 2004; van Ingen et al. 2009) have been a recent

focus of attention. A recently published book was

devoted to the ecology of mycobacteria and their

impact on human and animal health (Kazda et al.

2009).

Readers should pay special attention to biofilms,

aerosols, resistance to disinfectants, and

myco-bacterioses as professional diseases. Several

spe-cific phenomenona are typical for mycobacteria:

Isolation of mycobacteria from the environment is

hampered by their slow or limited growth

in vitro

.

Mycobacteria are frequently overgrown by other

microorganisms present in the sample. To

over-come this obstacle, different decontamination

methods have proven to be effective, although

with negative consequences for the sensitivity of

the culture.

As is the case for other microorganisms

myco-bacteria can be detected and identified directly and

quantitatively using different molecular methods.

Mycobacteria survive for a long time in the

en-vironment and can be found in great numbers in

rivers that collect water from pastures, in river and

lake sediments and in soil.

The hydrophobic character of the mycobacterial

cell wall is responsible for their easy aerosolisation

over swimming pools and river water, by sea

break-ers as well as in the shower bath.

1.1. The database used

The publications on mycobacteria were retrieved

from the Web of Science

®

(Thomson Reuters)

data-base using the search profiles described in Table 1,

and directed to water, soil, plants and air. The

num-bers of results retrieved from the complete

data-base Science Citation Index Expanded (timespan:

1945 to 2012) are mentioned only to demonstrate

the huge number of sources available. We

acknowl-edge that the key words used for searching are too

general and also that many inappropriate papers

have been omitted. The most important papers

published from 2007 to 2012 have been selected for

this review using abstracts or full papers. However,

certain important references published before 2007

were also included. The utility “Analyse results” was

used for the selection of review articles.

1.2. The format used

The review follows the format of our recently

published reviews (Eyer and Hruska 2012; Hruska

and Franek 2012). Selected papers are presented in

tables with the basic key words in the first column,

full or shortened abstract in the second column

and the link to the List of References in the third

column. This format is easy-to-navigate, supplies

readers with more information and minimises the

misinterpretation of papers through a subjective

wording by the authors of the review. The text in

the tables contains several format imperfections,

which exist in the Web of Science

®

database and

are caused by transmission and copying of data

between various information sources.

2. Selected review articles (Table 2)

(4)

3. Mycobacteria in water (Table 3)

Mycobacteria are present in most natural

wa-ters and piped water supplies. The main features

of mycobacteria as a public health risk have been

characterized already in 1984 as evident from the

sub-headings of a review published by Collins et

al. (1984):

Resistance of mycobacteria to chlorination

Access, persistence and colonization in piped

sup-plies

Is water the natural habitat of free-living

myco-bacteria?

Water as a vector for mycobacterial infections

Immune response to environmental mycobacteria

Mycobacteria as indicators of pollution

Most of the bacteria in drinking water

distribu-tion systems are associated with biofilms.

M. avium

has been described to survive in biofilms for more

than two to four weeks in culturable forms. Lehtola

et al. (2006) studied the survival of

M. avium

in

drinking water biofilms after the spiking of the

wa-ter using fluorescent

in situ

hybridization (FISH)

with an rRNA-targeted PNA probe. They

conclud-ed that culture examination seriously

underesti-mates the occurrence of

M. avium

in biofilms and

water. The study performed by Lehtola et al. (2007)

clearly proved that pathogenic bacteria entering

water distribution systems can survive in biofilms

for at least several weeks, even under conditions

of high-shear turbulent flow, and may be a risk to

water consumers. In order to understand microbial

communities in drinking water biofilms, Liu et al.

(2012) sequenced 16S rRNA in three faucet

bio-films using 454-pyrosequencing. They found that

the abundance of

Legionella

and

Mycobacterium

was affected by the residual chlorine in the water.

Most of the non-tuberculous mycobacteria not

only survive in water for a long time, but can grow

there as well (Kazda et al. 2009). Water, regardless

of origin and quality, can be contaminated by

my-cobacteria and, under specific conditions, can

jeop-ardise the users (Falkinham III 2003; Falkinham

2009a,b). Pickup et al. (2005) reported that

M. avium

subsp.

paratuberculosis

can be present in high

con-centrations in the river water in the catchments

area of pastures. Data presented in this paper bring

evidence of a higher incidence of Crohn’s disease

in districts bordering rivers. Exposure to waters

whose catchments include heavily grazed pastures

was associated with conspicuous clusters of Crohn’s

disease. The first of these involved a rural

com-munity of about 2000 people in England, in which

12 people developed Crohn’s disease between 1960

and 1983 (Allan et al. 1986). The village, which had

its own water supply from local springs, lay in a

hol-low surrounded by upland pastures grazed by cattle

in which clinical paratuberculosis (Johne’s disease)

was evident. A further suspicious cluster of seven

cases of Crohn’s disease amongst 285 graduates of

the Mankato West High School class of 1980 was

reported by Van Kruiningen and Freda (2001). All

seven students had been swimming in local ponds

and lakes.

A novel study into the diversity of mycobacteria

with regard to the physical and chemical

charac-teristics of the water in a coastal lagoon was

per-formed by Jacobs et al. (2009). The abundance of

mycobacteria was high; their presence was detected

in 96% of the stations sampled. There was a positive

correlation between the number of mycobacteria

and elevated temperatures, turbidity, nitrogen and

phosphorus components, whereas negative

cor-relations existed for the dissolved oxygen content,

depth and salinity.

A high hydrophobicity of mycobacteria leads to

their enrichment in natural ejected droplets and

transfer from water to air (Blanchard and Syzdek

1970). The enrichment factor for transfer of

myco-bacteria from water to air ranged from 68 to 15 000

in

M. intracellulare

(Parker et al. 1983). Obviously,

communal water poses a risk. Two case control

epidemiological studies carried out independently

in the United Kingdom each unexpectedly

iden-tified the availability of fixed hot water supplies

in the early childhood home as a significant risk

factor for the subsequent development of Crohn’s

disease (Gent et al. 1994; Duggan et al. 1998). An

urban cluster of Crohn’s disease possibly linked to

fully treated drinking water has been described by

Pierce (2009). Mycobacteria were found in 15% of

bottled water in Greece, in 4% of cases at a

concen-tration greater than 10

3

CFU/l (Papapetropoulou

et al. 1997).

4. Mycobacteria in soil (Table 4)

M. avium

subsp

. paratuberculosis

present on

(5)

Survival of mycobacteria in soil for as long as one

year or longer is associated with amoebae or other

protozoa or with the shedding of mycobacteria by

wild ruminants, wild board, hairs, rabbits and other

animals. Mycobacteria from river sediments can be

transferred to soil by floods or by the ejection of

mi-cro droplets forming aerosols. Any of these transfer

mechanisms can explain the finding of

M. avium

subsp

. paratuberculosis

in amoebae from fields not

used for grazing. (White et al. 2010).

Other

M. avium

subspecies were studied to

de-termine sources of infection for patients (Kaevska

et al. 2011). A small number of studies were

con-cerned with the detection of

M. bovis

(Young et

al. 2005) or

M. leprae

in soil. The association was

observed between endemicity of leprosy in Africa

and India, the distribution of mycobacteria in soil

and water with respect to dry or wet season and

geographical distribution. The mycobacterial

iso-lates from soil were identified as

M. fortuitum

,

whereas the uncultured sequences obtained from

soil DNA fell into a few closely related groups,

ei-ther

M. fortuitum

or other fast-growing

mycobac-teria, like

M. tokaiense

, or

M. austroafricanum

and

M. heidelbergense

. However, the method described

in this study based on the sequencing of a 473 bp

region of the 16SrRNA gene, cannot be used to

dis-criminate many species that are human and animal

pathogens, i.e.,

M. tuberculosis, M. avium, M. bovis

and

M. leprae

, although sequences belonging to this

group were identified (Chilima et al. 2006; Lavania

et al. 2008; Turankar et al. 2012).

With regard to mycobacterial diversity in

poly-cyclic aromatic hydrocarbon-contaminated soils,

investigations have revealed the presence of certain

species typical for that environment. Cheung and

Kinkle (2001) studied the diversity of

mycobacte-ria in petroleum-contaminated soils. 16S rRNA

sequences were amplified and subjected to

tem-perature gradient gel electrophoresis analysis. All

of the sequences belonged to fast-growing

myco-bacteria, some of them similar to

M. monascense

and

M. chlorophenolicum

. A similar study was

con-ducted by Leys et al. (2005). The sequences

detect-ed in the contaminatdetect-ed soil belongdetect-ed to the species

M. frederiksbergense, M. austroafricanum, M.

pe-troleophilum

and

M. tusciae

. In a study conducted

on heavily contaminated soil in Southern Finland,

Denaturation gradient gel electrophoresis revealed

that 30% of the clone library of the contaminated

soil belonged to the genus

Mycobacterium

(Bjorklof

et al. 2009).

5. Mycobacteria in plants (Table 5)

The presence of mycobacteria in plant tissues

has been a concern owing to possible transmission

to animals and humans (Kazda et al. 2009). The

contamination of food of plant origin with

myco-bacteria has been reported already several

dec-ades ago (Nassal et al. 1974). Mycobacteria were

found in fruits and vegetables, such as

strawber-ries, radish, cucumbers etc. mainly in edible parts

which were close to, or beneath the soil surface.

Crucially, mycobacteria were present, although

in smaller numbers, even after the washing of the

fruits. In the same study, the first experiments

demonstrating the presence of bacteria inside

fruits were reported. This finding was explained

by root uptake of bacteria. In the past couple of

decades, the numbers of papers which have

con-nected mycobacteria to food contamination and

which have recognised its impact on animal and

human health have been increasing (Kaevska and

Hruska 2010). Mycobacteria were detected also in

seven out of 121 vegetable samples which posed

a danger to HIV-infected individuals (Yajko et al.

1995). A later study compared the genotypes of

M. avium

isolates from patients and foods and

(6)

6. Mycobacteria in air (Table 6)

Mycobacteria in air are associated with dust or

particles originating from water or soil. Tuberculous

mycobacteria can be spread by dried sputum or

ex-crements. The transmission of

M. tuberculosis

and

M. bovis

in droplets ejected by patients suffering

from open forms of pulmonary tuberculosis is a

special risk. The time of exposure, quantity and

virulence of the pathogen, frequency and intensity

of coughing, air exchange rate in the room and many

factors related to the endangered person sharing

the same room play a role in the dissemination of

tuberculosis. It is obvious that species and

con-centration of mycobacteria in the air depend on

many factors. House dust samples was collected

from vacuum cleaners, homogenised by vigorous

shaking, and sieved. Mycobacteria were found

with both qPCR and traditional culture methods

in all 20 dust samples tested. The median cell count

was 10

6

cells/g and the median colony count was

10

3

CFU/g. Identification of samples was not

possi-ble by qPCR, but the species isolated by culture were

M. nonchromogenicum

,

M. kumamotonense

,

M.

ter-rae

,

M. avium

complex and

M. gordonae

(Torvinen

et al. 2010). The contamination of air with

mycobac-teria in a peat moss processing plant was assessed

by Cayer et al. (2007). A fragment of the 16S rRNA

gene was amplified, cloned and sequenced.

Forty-nine mycobacterial clones were obtained, most of

which were

M. intracellulare

species. The other

detected mycobacteria were

M. graecum

,

M. inter-jectum

,

M. bohemicum

and

M. smegmatis

.

M. avium

subsp

. paratuberculosis

was also detected in dust

on dairy farms (Eisenberg et al. 2009).

Mycobacteria in dust do not pose a unique risk of

harm for humans and animals. They only

supple-ment the other microorganisms, allergens, mites,

pesticides and other foreign bodies which may have

an adverse effect and are disseminated by means of

dust. Appropriate house and street cleaning

tech-nology should be thoroughly defined and required.

Vacuum cleaners must be tested for efficiency and

the sweeping of streets using hand held blowers

should be prohibited.

Mycobacteria were detected in the air of a

hos-pital therapy pool environment (Angenent et al.

2005). Among the indoor air sequences, there were

a total of 77 belonging to mycobacterial rRNA

genes. No mycobacteria were detected in the

out-side air sample. Perkins et al. (2009) sampled water

and aerosol samples from showers in a stem cell

transplantation unit. From the sequences obtained

and analysed, the most notable potential pathogen

identified was

M. mucogenicum

.

7. Identification of mycobacteria (Table 7)

Classical culture using solid or liquid media with

the identification of colonies using different

meth-ods was a standard method for more than 100 years.

The sample has to be decontaminated to prevent an

overgrow by the other microorganisms. Waiting for

results for several weeks or months and the inability

to determine the concentrations of mycobacteria in

a sample means that the popularity of culture has

waned. Nowadays, sophisticated, instrumental

ana-lytical methods based on DNA or RNA specificity

or determination of specific proteins is preferred. A

description of these methods is outside of the scope

of this review and the reader is directed elsewhere

for this information (Cerqueira et al. 2008; Nayak

et al. 2009).

The identification of mycobacteria in

environ-mental samples can be achieved using different

ap-proaches. In several studies isolated mycobacterial

DNA has been subjected to sequencing. Using this

method, the mycobacterial diversity in different

environments can be assessed. The most commonly

used gene, 16S rRNA, has variable and conserved

regions within the genus. For sequencing of the

genus

Mycobacterium

,

hsp65, dnaJ,

or

rpoB

genes

have been used (Mendum et al. 2000; Angenent

et al. 2005; Feazel et al. 2009). Next generation

sequencing based on pyrosequencing techniques

has also been used for the identification of

bacte-rial and mycobactebacte-rial diversity (Liu et al. 2012;

Gomez-Alvarez et al. 2012). The discovery of

inser-tion sequences which are specific for certain

my-cobacterial species or complexes has been crucial

for their direct detection using PCR or real time

PCR. IS

900

is specific for

M. avium

subsp.

para-tuberculosis

and is the most widely used sequence

for its detection (Pickup et al. 2005, 2006; Whan

et al. 2005; Torvinen et al. 2010). For detection of

M. avium

subsp.

avium

and

M. avium

subsp.

homi-nissuis

IS

901

and IS

1245

are used most commonly

(Kaevska et al. 2011). For direct detection of

M. ul-cerans

and

M. marinum

, PCR and real time PCR

(7)

Humic acids and other organic material in soil have

been the biggest obstacle for extracting microbial

DNA due to their inhibitory effects. The diversity

of mycobacteria in soil was most often assessed

using Denaturation gradient gel electrophoresis

or T-RFLP followed by cloning and sequencing

(Mendum et al. 2000; Niva et al. 2006; Kopecky

et al. 2011).

[image:7.595.323.538.79.800.2]

Many other methods including hybridisation

as-says, flow cytometry or MALDI-TOF have been

employed for the identification of mycobacteria,

though they are so far restricted to bacterial isolates

or clinical material. A suitable method should be

selected according to the specific aims, the matrix

to be analysed, specificity and sensitivity required,

accuracy needed, time available for the

determina-tion, etc.

Table 1. Search profiles used and numbers of the results retrieved

Web of Science databases = SCI-EXPANDED, SSCI, A&HCI, Lemmatization = On

Timespan All years 2007–2012

Water

Topic = (mycobact* AND water AND (drinking OR potable OR tap OR surface OR river OR swimming OR plumbing OR household OR tub))

Results 532 231

Selected 83

Cited in Table 3 55

Review articles in Table 2 12

Soil

Topic = (mycobact* AND soil)

Results 803 349

Selected 92

Cited in Table 4 23

Plants

Topic = (mycobact* AND (plant* OR vegetable*))

Results 1099 612

Selected 29

Cited in Table 5 12

Air

Topic = (mycobact* AND (air OR aerosol))

Results 1136 503

Selected 35

Cited in Table 6 18

Review articles in Table 2 6 _{Table 2. S}

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, a

s de

pic

te

d by m

ultilo

cu

s s

equenc

e analy

si

s.

M

ost c

linic

ally sig

nif

ic

an

t c

as

es of t

ho

se or

gani

sms in

volve

d c

at

he

ter

-r

el

at

ed inf

ec

tions

. T

he

y ar

e su

sc

eptible t

o mo

st an

timi

-cr

obi

al agen

ts

, but lik

e ot

her ra

pidly g

row

ing m

yc

ob

ac

ter

ia

, t

he

y ar

e r

esi

st

an

t t

o f

irst

-line an

tit

ub

er

culou

s agen

ts

. A r

ev

ie

w

of t

he c

as

es of

M. m

ucogen

icu

m

c

om

ple

x inf

ec

tion in t

he lit

era

tur

e i

s addr

ess

ed her

e, a

s we

ll a

s two additional c

as

es of t

he

clo

se

ly r

el

at

ed sp

ec

ie

s

M

yco

bacter

iu

m a

ub

ag

nen

se

.

A

de

kambi

[image:7.595.63.540.130.772.2]

(8)

M et al wor ki ng flu id s Pot en tial demo gra phic r isk f ac tors f or out br eak

s of r

espira

tor

y di

se

as

e due t

o w at er -b as ed me talwor king fluid s (MW Fs) wer e in ve stig at ed t hr oug h s yst ema tic r ev ie

w of publi

she d out br eak in ve stig ations . S ear ch t er ms wer e s ele ct

ed by a m

ultidi sc iplinar y te am, a ssi st

ed by an e

xp er ienc ed librar y inf or ma tion s er vic e. S everal c om put er ize d lit era tur e d at ab as es wer e s ear che d f or ar tic le s publi she d b etwe en J an uar

y 1990 and O

ct

ob

er 2011, r

el

ating t

o ill he

alt

h out

br

eak

s due t

o MW Fs . P ap ers me eting t he s ear ch c rit er ia wer e r ev ie we

d in de

tail, and t

heir r ef er enc es c he ck ed f

or additional ar

tic

le

s. S

tudy de

sig

n and demo

gra

phic de

tail

s of t

he out br eak wer e e xtrac te d f rom t he s ele ct ed ar tic le

s and en

ter ed in to st and ar di ze d e videnc e t able s. Thir ty -five ar tic le s r el ating t o in ve stig ations

of 27 out

br

eak

s of r

espira

tor

y ill he

alt h a ttr ibut ed t o MW F e xp osur e wer e iden tifie

d. The ma

jor

ity of r

ep or ts wer e c as e s er ie

s of di

s-ea

se or ob

ser va tional c ro ss -s ec tional st udie

s of s

ym

pt

oms and h

yg iene me asur emen ts . Eig

ht of t

he out br eak in ve stig ations inc lude d an e lemen

t of c

as e-c on tr ol analy sis . M ost out br eak s wer e f rom t he USA

, had o

cc

ur

re

d in l

ar

ge c

ar

- or aer

ona utic al-man uf ac tur ing pl an ts

, and wer

e a ss oc ia te d w ith t he u

se of c

en tral s har ed sum ps . H yg iene st udie s ha

ve not demonstra

te d c onsi st en t r isk f ac tors f or re spira tor y out br eak

s, in t

er

ms of t

he ty

pe of MW

F utili

ze

d, de

gr

ee of mic

robi

al c

on

tamina

tion, or le

ve

ls of p

ers onal e xp osur e. Si x st udie s wer e iden tifie d t ha t f ound wor kers w ith MW F e xp osur e dur ing out br eak s wer e mor e lik ely t o r ep or t r espira tor

y or s

yst emic sy m pt oms t han une xp os ed c on tr ol wor kers . Si x c as e-c on tr ol analy se s wer e al so iden tifie d t ha t f ound wor kers w ith e xtr insic aller gic alve oliti s (E A A) wer e mor e lik ely t o demonstra te c er tain imm une r esp ons es t o mic robi al c on taminan

ts and/or u

se d MW Fs t han wor kers w ithout E A A . D espit

e a n

umb

er of de

taile

d wor

kpl

ac

e and imm

unolo

gic

al st

udie

s of a

st

hma and alve

oliti s out br eak s in MW F-e xp os ed wor kf or ce

s, our underst

anding of t

heir ae tiolo gy r emains limit ed. Bur ton e t al. 2012 Fluore scence

in situ h

ybr

id

iz

ation,

peptide nucleic ac

id

s,

lo

cke

d nucleic ac

id

s

Fluor

es

cenc

e in sit

u h ybr idi za tion (FI SH) i

s a we

ll-e st abli she d t ec hnique t ha t i s u se d f

or a v

ar

ie

ty of pur

po se s, rang ing f rom pa tho gen de te

ction in c

linic al di ag no stic s t o t he de ter mina

tion of c

hr

omo

somal st

ability in st

em c ell r es ear ch. T he k ey st ep of FI SH in volve s t he de te

ction of a n

uc

leic ac

id r

eg

ion and a

s suc

h, DNA mole

cule s ha ve ty pic ally b een u se d t o pr ob e f or t he se quenc

es of in

ter est . H owe ver , sinc e t he t ur

n of t

he c

en

tur

y, an inc

re

asing n

umb

er of l

ab ora tor ie s ha ve st ar te d t

o move on

to t

he mor

e r

obu

st DNA mimic

s me tho ds , mo st not ably p

eptide and lo

ck

ed n

uc

leic ac

id

s (PNA and L

NA). In t

hi s r ev ie w , we w ill c over t he st at e-of -t he-ar

t of t

he dif

fer

en

t DNA mimic

s in r

eg ar d t o t heir a pplic ation a s ef fic ien t mar kers f or t he pr es enc e of indiv idu al mic robi al c ell

s, and c

onsider t heir p ot en tial adv an tage

s and pitf

all

s. A

vail

able PNA pr

ob es ar e t hen r ea ss ess ed in t er

ms of s

ensitiv

ity and sp

ec ific ity u sing rR NA d at ab as es

. In addition, we al

so a tt em pt t o pr edic t t he a pplic

ability of DNA

mimic

s in we

ll-k now n t ec hnique s a tt em pting t o de te

ct in sit

u low n

umb

er of c

opie

s of sp

ec ific n uc leic ac id s equenc es suc h a s ca taly ze d r ep or ter de po sition (C A

RD) and r

ec

og

nition of indiv

idu al gene s (R IN G) FI SH. Cer queira

et al. 2008

En vi ronment al m ycob ac ter ia A lth oug h t he en vir onmen tal m yc ob ac ter ia ar e s low g row ing r el ative t o ot her mic ro or gani

sms in w

at

er and s

oil whic

h would sug

-ge st t ha t t he y ar e p oor c om pe tit ors , c om pensa ting f ac tors p er mit sur viv al, g row

th and p

ersi

st

enc

e in na

tural and h

uman-eng ine er ed en vir onmen ts . F ac tors suc h a s t he h ydr ophobic , lipid-r ic h im per me able en ve lop

e, biofilm f

or ma tion, ac id r esi st anc e, anaer obic sur viv al and me ta boli

sm of r

ec alc itran t c arb on c om pound s p er mit sur viv

al and g

row

th of t

he en vir onmen tal m yc ob ac ter

ia in a w

ide range of

na

tural and h

uman-eng ine er ed ha bit at s. Hig h n umb

ers of en

vir onmen tal m yc ob ac ter ia ar e f

ound in c

oa

st

al s

w

am

ps and e

st uar ie s and bor eal, p ea t-r ic h f or est s oil

s and w

at

ers

. The h

ydr

ophobic sur

fac

e r

esult

s in c

onc

en

tra

tion of t

he en vir onmen tal m yc ob ac ter ia a t in ter -fac es (air -w at

er and sur

fac

e-w

at

er) and in aer

os oli ze d dr ople ts e je ct ed f rom w at er

. The sur

viv

al and g

row

th in pr

ot

ozo

a and amo

eb ae per mit en vir onmen tal m yc ob ac ter ia t o p ersi

st in ha

bit at s subj ec t t o pr ed

ation and lik

ely le

d t

o sur

viv

al and g

row

th in phago

cy tic c ell s of animal s. F inally , s low g row th allow

s time f

or m yc ob ac ter ial c ell s t o ad apt t o c hang ing c onditions b ef or e lo

ss of v

(9)

Ecolo

gy of m

ycob

ac

ter

ia

A ma

jor

ity of t

he

M

yco

bacter

iu

m

sp

ec

ie

s, c

alle

d t

he non

tub

er

culou

s m

yc

ob

ac

ter

ia (N

T

M), ar

e na

tural inha

bit

an

ts of na

tural

w

at

ers

, eng

ine

er

ed w

at

er s

yst

ems

, and s

oil

s. A

s a c

ons

equenc

e of t

heir ubiquit

ou

s di

str

ibution, h

umans ar

e sur

rounde

d by

the

se opp

or

tuni

stic p

at

ho

gens

. A c

ar

dinal f

ea

tur

e of m

yc

ob

ac

ter

ial c

ell

s i

s t

he pr

es

enc

e of a h

ydr

ophobic

, lipid-r

ic

h out

er

membrane. T

he h

ydr

ophobic

ity of N

T

M i

s a ma

jor de

ter

minan

t of aer

os

oli

za

tion, sur

fac

e adher

enc

e, biof

ilm-f

or

ma

tion,

and di

sinf

ec

tan

t-and an

tibiotic r

esi

st

anc

e. T

he N

T

M ar

e oligotr

ophs

, a

ble t

o g

row a

t low c

arb

on le

ve

ls [> 50 µg a

ssimil

a-ble or

ganic c

arb

on (A

O

C

) l

-1)], mak

ing t

hem ef

fe

ctive c

om

pe

tit

ors in low n

utr

ien

t, and di

sinf

ec

te

d en

vir

onmen

ts (

dr

ink

ing

w

at

er). Biof

ilm f

or

ma

tion and oligotr

oph

y le

ad t

o sur

viv

al, p

ersi

st

enc

e, and g

row

th in dr

ink

ing w

at

er di

str

ibution s

yst

ems

. In

addition t

o t

heir r

ole a

s h

uman and animal p

at

ho

gens

, t

he w

ide

spr

ead di

str

ibution of N

T

M in t

he en

vir

onmen

t, c

ouple

d w

ith

their a

bility t

o de

grade and me

ta

boli

ze a v

ar

ie

ty of c

om

ple

x h

ydr

oc

arb

ons inc

luding p

ollut

an

ts

, sugge

st

s t

ha

t N

T

M ma

y b

e

agen

ts of n

utr

ien

t c

yc

ling

.

Falk

in

-ham 2009a

W

ater and m

ycob

ac

ter

ia

Non

tub

er

culou

s m

yc

ob

ac

ter

ia (N

T

M) ar

e en

vir

onmen

tal opp

or

tuni

stic p

at

ho

gens of h

umans and animal

s. T

he

y ar

e f

ound in

a w

ide v

ar

ie

ty of ha

bit

at

s t

o whic

h h

umans ar

e e

xp

os

ed, inc

luding dr

ink

ing w

at

er di

str

ibution s

yst

ems and hou

se

hold w

at

er

and plumbing

. In t

ha

t r

eg

ar

d, t

he

y ar

e di

stinc

t f

rom t

heir oblig

at

e p

at

ho

genic r

el

ative

s, t

he memb

ers of t

he

M

yco

bacter

iu

m

tu

bercu

lo

si

s

c

om

ple

x. O

w

ing t

o t

he pr

es

enc

e of N

T

M in t

he h

uman en

vir

onmen

t, h

uman ac

tiv

itie

s ha

ve had dir

ec

t im

pac

ts

on t

heir e

colo

gy and t

her

eby t

heir e

pidemiolo

gy

. N

T

M ar

e oligotr

ophic

, a

ble t

o g

row a

t low or

ganic ma

tt

er c

onc

en

tra

tions

and over a w

ide range of t

em

pera

tur

es

, and e

ven a

t low o

xy

gen c

onc

en

tra

tions

. T

hu

s, N

T

M ar

e nor

mal inha

bit

an

ts of na

tu

-ral w

at

ers and dr

ink

ing w

at

ers

. Di

sc

over

y of t

he pr

es

enc

e of N

T

M

-p

ollut

ed s

oil

s i

s not sur

pr

ising in lig

ht of t

he a

bility of

N

T

M t

o de

grade a v

ar

ie

ty of h

ydr

oc

arb

on p

ollut

an

ts

. A ma

jor h

uman ac

tiv

ity s

ele

cting f

or t

he g

row

th and pr

edominanc

e of

m

yc

ob

ac

ter

ia in ha

bit

at

s i

s di

sinf

ec

tion. In c

om

par

is

on t

o ot

her b

ac

ter

ia

, N

T

M ar

e di

sinf

ec

tan

t, he

av

y me

tal and an

tibiotic

re

si

st

an

t. T

her

ef

or

e, t

he u

se of an

y an

timic

robi

al agen

t s

ele

ct

s f

or m

yc

ob

ac

ter

ia

. U

se of di

sinf

ec

tan

t in dr

ink

ing w

at

er tr

ea

t-men

t s

ele

ct

s f

or m

yc

ob

ac

ter

ia t

ha

t c

an g

row and c

ome t

o pr

olif

era

te in dr

ink

ing w

at

er di

str

ibution s

yst

ems in t

he a

bs

enc

e of

di

sinf

ec

tan

t-sensitive c

om

pe

ting mic

ro

or

gani

sms

. N

T

M s

ele

ction ma

y al

so o

cc

ur a

s a c

ons

equenc

e of an

tibiotic

s in dr

ink

ing

w

at

er s

our

ce

s.

Falk

in

-ham 2010

Ra

pidly g

ro

w

ing

m

ycob

ac

ter

ia i

nfe

ction

and tre

atment

Ra

pidly g

row

ing m

yc

ob

ac

ter

ia (R

GM) ar

e ubiquit

ou

s in na

tur

e and w

ide

ly di

str

ibut

ed in w

at

er

, s

oil and animal

s. D

ur

ing t

he p

ast

thr

ee de

cade

s we ha

ve ob

ser

ve

d a not

able inc

remen

t of inf

ec

tions c

au

se

d by R

GM, b

ot

h lo

cali

ze

d and di

ss

emina

te

d, a

s we

ll a

s no

so

-comi

al out

br

eak

s of c

on

tamina

te

d me

dic

al e

quipmen

t. The mic

robiolo

gic

al di

ag

no

sis of R

GM inf

ec

tions inc

lude

s dir

ec

t mic

ro

sc

opic

ob

ser

va

tion and c

ult

ur

e. The t

ax

onomic iden

tific

ation i

s p

er

for

me

d by phenoty

pic

, bio

chemic

al, c

hr

oma

to

gra

phic and mole

cul

ar

biolo

gy t

ec

hnique

s. The tr

ea

tmen

t diff

ers f

rom t

ha

t of ot

her m

yc

ob

ac

ter

io

sis lik

e t

ub

er

culo

sis

, ow

ing t

o t

he v

ar

ia

ble in v

itr

o su

sc

ep

-tibility of t

he sp

ec

ie

s of t

hi

s g

roup. The R

GM ar

e r

esi

st

an

t t

o c

on

ven

tional an

tit

ub

er

culou

s dr

ug

s, but c

an b

e su

sc

eptible t

o br

oad

sp

ec

tr

um an

timic

robi

al agen

ts

. In t

hi

s st

udy we c

ommen

t on t

he sig

nific

an

t a

sp

ec

ts of h

uman inf

ec

tions by R

GM, inc

luding t

heir

biolo

gy

, e

pidemiolo

gy

, p

at

holo

gy

, mic

robiolo

gic

al di

ag

no

sis

, t

ax

onomic iden

tific

ation, an

timic

robi

al su

sc

eptibility and tr

ea

tmen

t.

G

ar

ci

a-Mar

to

s

and Gar

ci

a-Ag

udo

(10)

W

ater

, milk and me

at

M. a

. p

ar

atu

bercu

lo

si

s

M

yco

bacter

iu

m av

iu

m

sub

sp.

pa

ratu

bercu

lo

sis

(Ma

p) i

s t

he c

au

se of J

ohne’

s di

se

as

e, a c

hr

onic inf

ec

tion of t

he g

ut

, in r

uminan

t

animal

s t

ha

t pr

ov

ide milk and/or me

at f

or h

uman c

onsum

ption. Ma

p al

so ma

y b

e in

volve

d in Cr

ohn

’s di

se

as

e and ty

pe I di

ab

et

es in

humans

. Alt

houg

h t

he r

ole of Ma

p in h

uman di

se

as

es ha

s not b

een e

st

abli

she

d, minimi

zing t

he e

xp

osur

e of h

umans t

o t

he or

gan

-ism i

s c

onsider

ed de

sira

ble a

s a pr

ec

autionar

y me

asur

e. Inf

ec

te

d animal

s c

an s

he

d Ma

p in f

ec

es and milk

, and t

he or

gani

sm c

an

be

come di

ss

emina

te

d in ti

ssue

s r

emot

e f

rom t

he g

ut and it

s a

ss

oc

ia

te

d ly

m

ph no

de

s. The pr

es

enc

e of a

t le

ast s

ome Ma

p in ra

w milk

and me

at and in na

tural w

at

ers i

s lik

ely

, but t

he n

umb

ers of Ma

p in t

ho

se f

oo

ds and w

at

ers s

hould b

e r

educ

ed t

hr

oug

h c

ook

ing or

pur

ific

ation. The a

vail

able inf

or

ma

tion r

el

ating t

o Ma

p in milk and d

air

y pr

oduc

ts

, me

at

s, and dr

ink

ing w

at

er i

s r

ev

ie

we

d her

e f

or

ass

essmen

t of t

he r

isk

s of e

xp

osur

e t

o Ma

p f

rom c

onsum

ption of suc

h f

oo

ds and w

at

er

.

Gill e

t al.

2011

W

ater

, fo

od and fe

ed

Pa

pers on m

yc

ob

ac

ter

ia in f

oo

d, f

ee

d and w

at

er

, publi

she

d b

etwe

en 1945 and 2010 and inde

xe

d in t

he d

at

ab

as

e W

eb of S

cienc

e (R)

(Thoms

on Re

ut

ers) wer

e rank

ed ac

cor

ding t

o a

ut

hors

, instit

utions

, c

oun

tr

ie

s and s

our

ce tit

le

s. The t

ot

al n

umb

er of p

ap

ers on m

yc

o-bac

ter

ia and f

oo

d and m

yc

ob

ac

ter

ia and w

at

er wer

e 1486 and 1419, r

esp

ec

tive

ly. M

or

e t

han 40% of p

ap

ers ha

ve b

een publi

she

d in

the l

ast five ye

ars

. In addition t

o public

ations in p

eer r

ev

ie

we

d j

our

nal

s t

he ar

chive

s of Pr

oME

D-mail and t

he R

apid Aler

t S

yst

em f

or

Fo

od and F

ee

d of t

he E

ur

op

ean U

nion wer

e al

so s

ear

che

d. I

t i

s e

viden

t t

ha

t m

uc

h a

tten

tion i

s b

eing p

aid t

o m

yc

ob

ac

ter

ia in f

oo

d,

fe

ed and w

at

er a

s t

he

y lik

ely p

os

e a public he

alt

h r

isk

.

Kae

vs

ka

and Hru

sk

a

2010

Pul

monar

y d

is

ea

se

s

M. av

iu

m

com

ple

x

M

yco

bacter

iu

m av

iu

m

c

om

ple

x (M

A

C

) c

onsi

st

s of non

tub

er

culou

s m

yc

ob

ac

ter

ia t

ha

t c

au

se di

se

as

e in imm

uno

com

pr

omi

se

d and

imm

uno

com

pe

ten

t ho

st

s. The or

gani

sms ar

e ubiquit

ou

s in t

he en

vir

onmen

t, and ac

qui

sition o

cc

urs t

hr

oug

h inge

stion or inhal

ation

of aer

os

ol

s f

rom s

oil, w

at

er

, or biofilms

. Di

se

as

e ma

y manif

est a

s di

ss

emina

te

d inf

ec

tion, s

of

t ti

ssue inf

ec

tion, c

hr

onic pne

umoni

a,

or h

yp

ers

ensitiv

ity pne

umoniti

s. Non

tub

er

culou

s m

yc

ob

ac

ter

ia ar

e inc

re

asing

ly a

ss

oc

ia

te

d w

ith pulmonar

y di

se

as

e, w

ith M

A

C

being t

he mo

st c

ommon non

tub

er

culou

s m

yc

ob

ac

ter

ia t

o c

au

se pulmonar

y di

se

as

e in t

he U

nit

ed S

ta

te

s. Pulmonar

y s

ym

pt

oms

,

no

dul

ar or c

av

itar

y op

ac

itie

s on a c

he

st radio

gra

ph or hig

h-r

es

olution c

om

put

ed t

omo

gra

phic s

can w

ith m

ultif

oc

al br

onc

hie

ct

asi

s

and m

ultiple small no

dule

s, plu

s p

ositive c

ult

ur

e r

esult

s f

rom two sput

um sp

ec

imens or one br

onc

ho

sc

opic sp

ec

imen ar

e c

onsi

st

en

t

w

ith M

A

C pulmonar

y di

se

as

e. T

re

atmen

t c

onsi

st

s of a mac

rolide, r

ifam

yc

in, and e

thambut

ol g

iven t

hr

ee time

s we

ek

ly f

or nonc

av

i-tar

y di

se

as

e and d

aily w

ith or w

ithout an amino

glyc

oside f

or c

av

itar

y di

se

as

e.

Ka

sp

er

-ba

uer and

D

ale

y

2008

Lu

ng

d

is

eas

e c

aus

ed

by m

ycob

ac

ter

ia

Non

tub

er

culou

s m

yc

ob

ac

ter

ia (N

TM) ar

e r

esilien

t b

ac

ter

ia t

ha

t g

row in v

irt

ually an

y en

vir

onmen

t, e

sp

ec

ially t

ho

se wher

e c

om

pe

t-ing mic

ro

or

gani

sms ar

e de

str

oye

d, suc

h a

s in c

hlor

ina

te

d w

at

er

. The

y ha

ve b

een di

sc

over

ed in s

oil, du

st

, f

oo

d, w

at

er

, and dome

stic

and w

ild animal

s. Non

tub

er

culou

s m

yc

ob

ac

ter

ia t

end t

o inf

ec

t indiv

idu

al

s w

ith lo

cal (

e.g

., d

amage

d s

kin or lung) or s

yst

emic (

e.g

.,

H

IV

, dr

ug

s, malig

nanc

y) def

ec

ts in ho

st def

enc

e, and t

heir inc

idenc

e and pr

ev

alenc

e ha

ve c

onsi

st

en

tly inc

re

as

ed in t

he l

ast de

cade.

Diffic

ulty ma

y ar

ise in de

ter

mining whe

ther an i

sol

at

ed N

TM f

rom a mic

robiolo

gic

al sam

ple i

s in f

ac

t a c

on

taminan

t or a p

at

ho

-genic or

gani

sm. In t

hi

s r

ev

ie

w, we di

sc

uss t

he im

por

tan

t m

yc

ob

ac

ter

ia in

volve

d in lung di

se

as

e, f

ac

tors t

ha

t pr

edi

sp

os

e indiv

idu

al

s

to inf

ec

tion, and t

heir di

ag

no

sis and tr

ea

tmen

t ac

cor

ding t

o up

da

te

d g

uide

line

s. Eng

lis

h l

ang

uage public

ations in ME

DL

IN

E and

ref

er

enc

es f

rom r

ele

van

t ar

tic

le

s f

rom J

an

uar

y 1, 1990 t

o J

une 28, 2009 wer

e r

ev

ie

we

d. K

ey

wor

ds s

ear

che

d wer

e “

non

tub

er

culou

s”,

“m

yc

ob

ac

ter

ia

”, “

di

ag

no

sis”

, and “

tr

ea

tmen

t”.

M

cGra

th

(11)

Cont

ac

t tr

ac

ing i

n pu

bl

ic

tr

ansp

or

t

While g

uide

line

s on c

on

tac

t trac

ing (C

T

) af

ter e

xp

osur

e t

o c

er

tain inf

ec

tiou

s p

at

ho

gens dur

ing air tra

ve

l e

xi

st

, no g

uid

anc

e

do

cumen

ts ar

e a

vail

able on C

T in r

esp

ons

e t

o p

ot

en

tial e

xp

osur

e on public g

round transp

or

t. W

e r

ev

ie

we

d s

cien

tif

ic and

non-sc

ien

tif

ic lit

era

tur

e on transmi

ssion of airb

or

ne p

at

ho

gens in public g

round transp

or

t and on f

ac

tors p

ot

en

tially inf

lu

-enc

ing transmi

ssion. W

e iden

tif

ie

d 32 r

ele

van

t public

ations (15 s

cien

tif

ic and 17

non-sc

ien

tif

ic

). M

ost of t

he s

ele

ct

ed st

udie

s

de

alt w

ith transmi

ssion of t

ub

er

culo

si

s. H

owe

ver

, t

he r

el

ation b

etwe

en tra

ve

l dura

tion, pr

oximity t

o t

he inde

x c

as

e and en

vi

-ronmen

tal f

ac

tors

, suc

h a

s ven

til

ation, on di

se

as

e transmi

ssion in public g

round transp

or

t i

s p

oor

ly underst

oo

d. Consider

ing

the dif

fic

ulty and pr

ob

ably limit

ed ef

fe

ctivene

ss of C

T in g

round transp

or

t, our r

esult

s sugge

st t

ha

t only e

xc

eptional c

ir

cum

-st

anc

es would ju

stif

y C

T. T

hi

s c

on

tra

st

s w

ith t

he hig

h le

ve

l of a

tt

en

tion C

T in air tra

ve

l s

eems t

o r

ec

eive in in

ter

na

tional

re

gul

ations and r

ec

ommend

ations

. W

e que

stion whe

ther t

he indic

ation f

or C

T s

hould b

e r

ev

isit

ed af

ter a r

is

k-b

enef

it a

ss

ess

-men

t t

ha

t t

ak

es in

to ac

coun

t e

xp

osur

e in b

ot

h g

round and air transp

or

t.

M

ohr e

t

al. 2012

D

ete

ction of mic

ro

or

gan

-isms u

si

ng bio

sens

or

s

Along w

ith u

sef

ul mic

ro

or

gani

sms

, t

her

e ar

e s

ome t

ha

t c

au

se p

ot

en

tial d

amage t

o t

he animal

s and pl

an

ts

. D

et

ec

tion and

iden

tif

ic

ation of t

he

se har

mf

ul or

gani

sms in a c

ost and time ef

fe

ctive w

ay i

s a c

hallenge f

or t

he r

es

ear

chers

. T

he f

ut

ur

e of

de

te

ction me

tho

ds f

or mic

ro

or

gani

sms s

hall b

e g

uide

d by bio

sens

or

, whic

h ha

s alr

eady c

on

tr

ibut

ed enor

mou

sly in s

ensing

and de

te

ction t

ec

hnolo

gy

. H

er

e, we aim t

o r

ev

ie

w t

he u

se of v

ar

iou

s bio

sens

ors

, de

ve

lop

ed by in

te

gra

ting t

he biolo

gic

al and

ph

ysic

oc

hemic

al/me

chanic

al pr

op

er

tie

s (

of tranduc

ers), whic

h c

an ha

ve enor

mou

s im

plic

ation in he

alt

hc

ar

e, f

oo

d, ag

ric

ult

ur

e

and bio

def

enc

e. W

e ha

ve al

so hig

hlig

ht

ed t

he w

ay

s t

o im

pr

ove t

he f

unc

tioning of t

he bio

sens

or

.

N

ay

ak e

t

al. 2009

Fre

e-l

iv

ing amo

eb

ae

M

yco

bacter

iu

m

sp

ec

ie

s e

volve

d f

rom an en

vir

onmen

tal r

ec

en

t c

ommon anc

est

or by r

educ

tive e

volution and l

at

eral gene

transf

er

. S

tra

te

gie

s s

ele

ct

ed t

hr

oug

h e

volution and de

ve

lop

ed by m

yc

ob

ac

ter

ia r

esult

ed in r

esi

st

anc

e t

o pr

ed

ation by en

vi

-ronmen

tal unic

ellul

ar pr

oti

st

s, inc

l

Mycobacteria in water, soil, plants and air: a review