Download Title-Isolation of Methicillin resistant Staphylococci among health

Title-Isolation of Methicillin resistant Staphylococci among health care workers
Abstract- Introduction- Hospital acquired infections by Methicillin resistant
Staphylococcus aureus (MRSA) and Methicillin resistant coagulase negative Staphylococci
(MR CONS) are important, and the usual source of infection is the health care worker. Proper
implementation of infection control measures can reduce the chance of these infections
Material and methods- Following the isolation of three post- operativeMRSA cases, a
prompt investigation was conducted by collecting anterior nare swabs & web space swabs of
health care workers. Results-Carrier rate of MRSA & CONS- MR from anterior nares was
10% & 36% respectively, and web spaces was 3% Conclusion- Prompt identification and
treatment of MRSA carrier can reduce the chance of patients acquiring these bacterial
infections.
Key wordsMethicillin- resistant Staphylococcus aureus, Nosocomial infection
IntroductionNosocomial infections or hospital acquired infections (HAI) causes increased morbidity,
mortality and cost among hospitalized patients. The incidence of HAI in the western
countries is5-10%and 20-30% in India. [1]Various organisms like Methicillin-resistant
Staphylococcus aureus (MRSA), extended spectrum beta-lactamase (ESBL) producers,
Pseudomonas, Acinetobacter, Enterobacteriaceaespeciescause HAI. Source of infection may
be of endogenous origin i.e. patients commensal floraor exogenous origin i.e.,from Health
care workers (HCW), other patients and the environment.
Staphylococcus is an important pathogen related to nosocomial infections.[2]
Rates of methicillin-resistant Staphylococcus aureus (MRSA)& methicillin resistant
coagulase negative Staphylococci (CONS MR)infections are increasing.
In a Japanese national surveillance, the incidence of MRSA hospital infections per 100
admissions was between 0.7 and 0.8 from 1999 to 2003[3]
MRSA was first isolated in 1961[4]& it is known to cause serious infections among
hospitalized patients. These pathogens are difficult to treat, as they need expensive
andcomparatively toxic antibiotics like vancomycin. Some strains have also developed partial
or complete resistance to vancomycin [5, 6].Another major problem with MRSA is its ability
to reside as normal flora among HCW’s in various sites like the nose, hands, axilla, perineum
etc. [7]These HCW’s can become important source of infection in the health care setting,
especially in OT, ICU, post operative wards etc.The carriage rate of MRSA among HCW is
4-6 % percent.
A sudden increase in post-operative wound infectionsin the Obstetrics and Gynecology
department of our hospital prompted this study.
Here we have estimatedthe MRSA and other methicillin resistant Staphylococci carriage
rates; nasal and web space, among HCW’s.
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Materials and methods
A study was conducted to screen HCW’s with MRSAand methicillin resistant CONS
carriage. Three patients developed postoperative wound infection with MRSA in August
2011 which prompted this study. All the doctors, nurses and the other HCW’s who came in
direct contact with the above patients were screened for nasal and web space carriage.Nasal
and web space of both the hands were collected from 39 Health care workers.
Procedure for nasal swabA sterile pre moistened cotton swab was introduced into both anterior nares and rotated for
5-6 seconds and immediately plated on blood agar and Mac Conkey agar plates.
Procedure for Web-space swabA sterilepre moistened swab was rubbed over the web spaces and the swabs immediately
plated on Blood agar and Mac Conkey agar plates.
The plates were incubated overnight at 37 degrees. The colonies on the plates were studied
by- Gram’s staining, catalase and slide coagulase test. Tube coagulase test was done.
Antibiotic sensitivity pattern was determined by Kirby-Bauer technique. Staphylococci
resistant to Cefoxitin 30 microgram disc were identified as MRSA /methicillin resistant
CONS and the resistance pattern noted.
Environmental swabs were also collected from various areas in the ward and OT to trace the
source of infection and the swabs processed.
The HCW’s with MRSA & CONS MR in the anterior nares or web space were identified as
carriers and advised to Apply1-2% Mupirocin ointment in the anterior nares- 2-3 times per day for 5 days.
 Use barrier precautions like gloves, mask while handling patients.
 Follow Universal/ Standard precautions.
 Avoid OT/ dressing of wounds for one week
Once the duration of treatment was complete the health care personnel was asked to submit
another nasal and web-space swab to make sure he/she was no longer a carrier.
ResultsNasal swabs from majority of the HCW’s i.e., 26 % yielded no growth, the rest 74% yielded
growth. Among the swabs with growth S. aureus was isolated in 16 % of HCW’s and CONS
from 58% of HCW’s.
(Table 1)
Most of the web space swabs yielded no growth i.e., 95%. Growth was seen in only 5% of the
swabs. Equal distribution of S.aureus and CONS seen i.e, 3% in the web space swab of
HCW’s (Table 1)
MSSA-Methicillin Sensitive Staphylococcus aureus
Methicillin resistant S. aureus nasal carriers was seen in 10% of the HCW’s
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Methicillin resistant CONS nasal carriers was seen in 36% of the HCW’s
In the web space methicillin resistant S. aureus and methicillin resistant CONS carrierswere
distributed equally i.e., 3% (Table 2)
Vancomycin sensitive Staphylococci 26 out of 31 i.e.,-84% of the strains are sensitive to
vancomycin
Vancomycin resistant Staphylococci- 5out of 31 i.e., 16% of the strains are resistant to
vancomycin
Environmental swabs yielded no growth.
DiscussionMajority of the HCW’s had CONS (58 %) in their anterior nares. Coagulase negative
Staphylococci by itself is not a major pathogen but it may cause disease in the
immunocompromised patients. The carrier rate for methicillin resistant CONS among HCW’s
in our study was 36%. A study by Akhtar N shows very carriage rate of 2.1% which is low
compared to our study. [8]
S. aureus was isolated less commonly from the nares (16%). MRSAcarrier rate in HCW’s
from anterior nares is 10%. This is more compared to the study conducted by Emma
Hittwhere MRSA was isolated in 4% of the health care workers tested.[9]
From the web spaces majority of the swabs yielded no growth(95%) the reason we attributed
probably was prior washing of the hands before giving the sample. MRSA carrier rate in the
web space was 3%. Other studies also reveal low MRSA rates like our study.[10]
Isolation of Methicillin resistant Staphylococci from HCW’s is significant due to the
possibility of them acting as source of infection to the patients.
Hence identification of Methicillin resistant Staphylococci carriers is important.
In our study majority of the strains were sensitive to vancomycin 84%, only 16% were
resistant to the drug. It must be remembered that vancomycin is the drug of choice for
methicillin resistant Staphylococci. Hence this drug must be used with care especially
following sensitivity testing.
Key MessageScreening of Health care workers for Methicillin resistant Staphylococci carriage should be
done periodically. Once identified proper treatment should be given. By this a significant
number of HAI can be prevented and patients managed better. Sensitivity testing of the
organism to vancomycin must be done routinely as many strains are developing resistance to
the drug.
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REFERENCES
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June 2005, Pages 172-175
4. Lin YC, Lauderdale TL, Lin HM, Chen PC, Cheng MF, Hsieh KS et al.An outbreak
of methicillin-resistant Staphylococcus aureus infection in patients of a pediatric
intensive care unit and high carriage rate among health care workers.J
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6. Centers for Disease Control & Prevention. Staphylococcus aureus resistant to
Vancomycin- United States. JAMA 2002; 288:824-825.
7. J.E.Coia, G.J. Duckworth, D.I. Edwards, M. Farrington, C. Fry, H.Humphreys et al.
Guidelines for Control and Prevention of methicillin resistant Staphylococcus aureus
(MRSA) in health care facilities. Journal of Hospital Infection.(2006)635; S1-S44
8. Akhtar N. Staphylococcal nasal carriage of health care workers. Journal of college of
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9. http://www.medscape.com/viewarticle/719841
10. Ravindra JS, Sujeet MM, Habib J. Screening for methicillin resiatant staphylococcus
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Table 1- Distribution of Staphylococci from various sites
Specimen
S. aureus
CONS
Nasal swab
Web space
swab
No Growth
Total
No
%
No
%
No
%
6
1
16
3
23
1
58
3
10
37
26
95
Table 2- Isolation of Methicillin resistant & sensitive strains
Specimen
MRSA
MSSA
CONS
CONS
Methicillin
Methicillin
resistant
sensitive
No %
No %
No %
No
%
Nasal swab 4
10
2
5
14 36
9
23
Web space 1
3
0
0
1
3
0
0
swab
39
39
No growth
No
10
37
Total
%
26 39
95 39
Figure 1
Nasal Carriage pattern
MRSA
MSSA
CONS MS
CONS MR
NG
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Figure 2
Web space carriage pattern
MRSA
MSSA
MR CONS
MS CONS
NG
Figure 3
Sensitivity of Staphylococci to Vancomycin
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