Dr.T.V.Rao MD

STENOTROPHOMONAS

MALTOPHILIA

AN EMERGING PATHOGEN

DR.T.V.RAO MD 1

STENOTROPHOMONAS MALTOPHILIA

• Stenotrophomonas maltophilia is an aerobic,

nonfermentative, Gram-negative bacterium. It is

an uncommon bacterium and human infection is

difficult to treat. Initially classified as

Pseudomonas maltophilia, S. maltophilia was

also grouped in the genus Xanthomonas before

eventually becoming the type species of the

genus Stenotrophomonas in 1993

DR.T.V.RAO MD 2

• Stenotrophomonas maltophilia bacteria, Coloured transmission electron micrograph (TEM). This aerobic Gram-negative bacterium, previously known as Pseudomonas maltophilia, can cause infections in humans and is resistant to many antibiotics. It thrives in wet and moist conditions, and mainly affects patients whose immune systems have been compromised by infection or weakness. A study published in 2008 identified this bacteria as having the capacity to rapidly develop into strains with increased drug resistance..

STENOTROPHOMONAS MALTOPHILIA

DR.T.V.RAO MD 3

ANTIBIOTIC USE PRODUCES NEWER

MICROBIAL INFECTIONS

• With the widespread use of antibiotics and dramatic

improvement in patients survival, newer organisms, such as

Stenotrophomonas maltophilia , Achromobacter

xylosoxidans and nontuberculous mycobacteria are

becoming more widespread. The reasons for their emergence

are complex but may relate to the selective pressure exerted by

repeated exposure to antibiotic therapy, improved laboratory

isolation techniques and enhanced reporting. All may be

associated with either simple colonisation or respiratory

exacerbations in those persistently colonised with large

numbers of these organism

DR.T.V.RAO MD 4

• S. maltophilia are slightly smaller (0.7–1.8 × 0.4–0.7 micrometers) than other members of the genus. They are motile due to polar flagella and grow well on MacConkey agar producing pigmented colonies. S. maltophilia are catalase-positive, oxidase-negative (which distinguishes them from most other members of the genus) and have a positive reaction for

extracellular DNase

CHARACTERISTICS OF MALTOPHILIA

DR.T.V.RAO MD 5

COLONIES OF STENOTROPHOMONAS MALTOPHILIA ON MACCONKEY

AGAR, INCUBATION PERIOD 3 DAYS AT 30°-35°C

DR.T.V.RAO MD 6

COLONIES OF STENOTROPHOMONAS MALTOPHILIA ON

MUELLER-HINTON AGAR. CULTIVATION 72 HOURS,

AEROBIC ATMOSPHERE, 28°C.

DR.T.V.RAO MD 7

• BIOCHEMICAL

REACTIONS

Oxidase negative

Acidifies maltose in

addition to glucose,

lactose ,sucrose

BIOCHEMICAL REACTIONS

DR.T.V.RAO MD 8

• S. maltophilia is ubiquitous in aqueous environments, soil and plants, including water, urine, or respiratory secretions; it has also been used in biotechnology applications. In immunocompromised patients, S. maltophilia can lead to nosocomial infections.

S. MALTOPHILIA CAN LEAD TO NOSOCOMIAL

INFECTIONS

DR.T.V.RAO MD 9

• Most cases of

infection tends to

occur through use of

hospital appliances

such as catheters,

I.V lines and

breathing tubes in immunocompromised

people.

CATHETERS AND I V LINES A SOURCE

OF INFECTION

DR.T.V.RAO MD 10

Reports from several

centres . This pathogen

primarily affects patients

with co-morbid illness

such as cystic fibrosis,

immunosuppression,

organ transplantation and

malignancies. Infections

related to S. maltophilia

are associated with high

morbidity and mortality

rates

EMERGING IMPORTANCE OF MALTOPHILIA

DR.T.V.RAO MD 11

EMERGING CONCERNS WITH

STENOTROPHOMONAS MALTOPHILIA

• Stenotrophomonas maltophilia has emerged as an important

opportunistic pathogen in the debilitated host. S maltophilia is

not an inherently virulent pathogen, but its ability to colonise

respiratory-tract epithelial cells and surfaces of medical devices

makes it a ready coloniser of hospitalised patients. S maltophilia

can cause blood-stream infections and pneumonia with

considerable morbidity in immunosuppressed patients.

Management of infection is hampered by high-level intrinsic

resistance to many antibiotic classes and the increasing

occurrence of acquired resistance to the first-line drug co-

trimoxazole. Prevention of acquisition and infection depends

upon the application of modern infection-control practices, with

emphasis on the control of antibiotic use and environmental

reservoirs. DR.T.V.RAO MD 12

• S maltophilia has few pathogenic

mechanisms and, for this reason,

predominantly results in

colonization rather than infection.

If infection does occur, invasive

medical devices are usually the

vehicles through which the

organism bypasses normal host

defenses. Otherwise, the

pathophysiology of this

nonfermentative aerobic gram-

negative bacillus does not differ

from other nonfermentative

aerobic organisms.

PATHOPHYSIOLOGY

DR.T.V.RAO MD 13

• In severely ill patients,

S. maltophilia causes a

wide range of infections

such as bacteremia,

pulmonary infections,

urinary tract infections,

wound infections,

meningitis and

endocarditis

S.MALTOPHILIA PRODUCE SEVERAL LIFE

THREATING INFECTIONS

DR.T.V.RAO MD 14

• S.maltophilia is a

growing source of

latent pulmonary

infections. S.

maltophilia

colonization rates in

individuals with

cystic fibrosis have

been increasing.

S.MALTOPHILIA AND CYSTIC FIBROSIS

DR.T.V.RAO MD 15

MORTALITY/MORBIDITY

• Mortality and morbidity relate to the inoculum of S maltophilia

that is able to bypass normal host defense mechanisms.

• If an intravenous infusion contains large numbers of S

maltophilia, then direct injection into the bloodstream may result

in the signs and symptoms associated with gram-negative

bacteremia.

• Similarly, in the urinary tract, if urological irrigation fluids that

contain large numbers of S maltophilia are used during an

invasive urological procedure, eg, cystoscopy, then gram-

negative bacteremia may occur with its attendant mortality and

morbidity, which depend on host factors.

DR.T.V.RAO MD 16

• TMP – SXT has been recommended

for use in the treatment of S.

maltophilia infections based on the

in vitro susceptibility data which

confirm its high activity and the

favorable outcomes observed in

patients treated with this agent [ .

Although the role of the combination

antimicrobial therapy in treating

infections due to strains that are

susceptible to TMP – SXT is

uncertain but the addition of one or

more agents to which the isolate is

susceptible in vitro is a reasonable

consideration if the patient is

critically ill or has an underlying

hematological malignancy

TMP-SXT IS DRUG OF CHOICE ?

DR.T.V.RAO MD 17

• Several reports have

shown that the prevalence

of strains that are resistant

to TMP – SXT is increasing

. The rate of resistance to

TMP – SXT ranges from

2% in Canada and Latin

America to 10% in Europe • Stenotrophomonas maltophilia resistant to

trimethoprim – sulphamethoxazole: an increasing

problem

• Asma M Al-Jasser

RESISTANCE TO TMP-SXT

DR.T.V.RAO MD 18

MOLECULAR MECHANISMS OF RESISTANCE IN

S.MALTOPHILIA

DR.T.V.RAO MD 19

• S. maltophilia exhibits an array of mechanisms that singularly or collectively contribute to its multidrug resistance status. Intrinsic resistance includes inducible efflux pumps and multiple β-lactamase expression but not mutations in the quinolone resistance–determining region . In addition, S. maltophilia can acquire resistance through integrons, transposons, and plasmids . Recently, class 1 integrons have been characterized from S. maltophilia strains isolated in Argentina and Taiwan, which indicates that they contribute to TMP/SMX resistance through the sul1 gene carried as part of the 3´ end of the class 1 integron

• Therapy for these infections

represents a significant

challenge both for the

clinician and the

microbiologist because of

this organism's high level of

antibiotic resistance to most

of the currently used agents

and methodological

difficulties in susceptibility

testing with this organism

THERAPEUTIC FAILURES A GREAT CONCERN

DR.T.V.RAO MD 20

• The microbiology laboratory

also plays a vital role in

controlling S. maltophilia

infections by continuous

monitoring of the

prevalence, the provision of

local Antibiogram data and

the performance of

synergistic studies which

may help to guide therapy

selection.

ROLE OF MICROBIOLOGY DEPARTMENTS

DR.T.V.RAO MD 21

• The proposed strategies to

prevent S. maltophilia

infection should be

encouraged and they

include: the avoidance of

inappropriate use of

antibiotics, the avoidance

of prolonged

implementation of foreign

devices, the reinforcement

of hand hygiene practices

and the application of

appropriate infection control

practices.

CONTROLLING MALTOPHILIA INFECTIONS

DR.T.V.RAO MD 22

EFFECTIVE HAND WASHING WILL REDUCE

SEVERAL CASES OF NOSOCOMIAL INFECTIONS

DR.T.V.RAO MD 23

DR.T.V.RAO MD 24

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REFERENCES

DR.T.V.RAO MD 25

• 1.Emerging Infectious diseases Volume 13, Number 4–April

2007

• 2 American society of Microbiology

• 3 science photo library

• Created by Dr.T.V.Rao MD for ‘e’ learning

resources for Microbiologists and Health

care Workers in Developing World

• Email

• doctortvrao@gmail.com

DR.T.V.RAO MD 26