The
Etiological Agents of Mastitis in Lactating Women
in Iran
..........................................................................................................................
Bakhshandeh-Nosrat
S (1), Ghazisaidi K (2), Ghaemi
E.O (3),
Fatemi Nasab F (4), Mohamadi M (5).
- Assistant Professor,
Obstetric and Gynecology Department, Golestan
University of Medical Sciences, Iran
- Professor, Microbiology
Department, Golestan University of Medical Sciences,
Iran
- Associate Professor,
Microbiology Department, Golestan University
of Medical Sciences, Iran
- Assistant Professor,
Immunology Department, Iran University of Medical
Sciences, Iran
- MS in medical
Microbiology, Tehran university of Medical Sciences,
Iran
Address correspondence to:
Bakhshandeh-Nosrat
S, email:
sb_nosrat@yahoo.com
..........................................................................................................................
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ABSTRACT
Mastitis
is an inflammatory condition of the breast;
and is usually associated with lactation,
and therefore called lactational mastitis.
The
two principle causes of mastitis are milk
stasis and infection. The aim of this study
was to evaluate the etiological agents of
mastitis in lactating women in Tehran, Iran
and to determine the bacterial pattern of
resistance.
A total
of 203 milk samples were taken from puerperal
women hospitalized in Tehran, and suffering
from mastitis during the years 2003-04.
These samples were examined by bacteriological
methods. After identification of the bacteria
by biochemical tests, their antibiotic sensitivity
was assessed by disk diffusion method.
From
203 samples, 26 samples (12.8%) were culture
positive, 21 (80.8%) were Coagulase negative
Staphylococcus and 5 (19.2%) samples were
Staphylococcus aureus.
All strains of S.aureus and Coagulase Negative
Staphylococcus were sensitive to Cloxacillin,
Fluxacillin and Dicloxacillin.
Our
findings showed that Staphylococcus aureus
and Coagulase negative Staphylococcus were
the major etiological agents of mastitis
in Iranian women.
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Key
words: mastitis, Staphylococcus aureus,
Coagulase Negative Staphylococcus
...........................................................................................................................
Mastitis is an inflammatory
condition of the breast. It is usually associated
with lactation, therefore it is also called lactational
mastitis. (1)
Mastitis usually occurs during
the second or thirds weeks opost partum (2). In
the majority of reports 74 to 95% of mastitis
occurs in the first 12 weeks post partum(3) and
it is seldom observed after 12th week post partum.(2)
Mastitis is relatively common
and the reported incidence varies from a few to
33% of lactating women (4, 5, and 6).
The two principle causes of
mastitis are milk stasis and infection. Milk stasis
is usually the primary cause, which may or may
not be accompanied by or progress to infection.
Milk stasis occurs when milk is not excreted completely.
Improper attachment of the neonate to the breast,
inability of the neonate to suck enough milk,
limitation of duration, frequency of lactation
and obstruction of lactational canals, can cause
milk stasis (1).
Proper conditions for bacterial
growth following milk accumulation may be accrued.
The most common isolated organisms
in mastitis are Staphylococcus aureus and Coagulase
negative Staphylococcus. Different types of streptococcus,
Gram negative bacilli like E.coli sometimes are
found (2, 7) Salmonella, Mycobacterium, Candida
and Cryptococcus species are seldom isolated (4).
Several routes have for the entry bacteria to
the breast have been suggested, through the lactiferous
ducts into a lobe; by haematogenous spread; and
through a nipple fissure and abrasions of the
nipple into the periductal lymphatic system. Nipple
fissure has been reported with increased frequency
in the presence of mastitis (7, 8).
Diagnosis of mastitis is usually
based on the clinical manifestations. Usually
one breast becomes hard, reddened, painful, inflamed,
and a reduction in milk secretion is observed
(4).
General signs such as fever
= 38.5°c, chill and malaise may be observed,
but it is not possible to distinguish infective
mastitis from non-infective mastitis by clinical
manifestation, therefore culturing of a milk sample
is recommended to diagnose infective organisms(2
).
Milk samples with more than
106 leukocytes and more than 103 bacteria /ml
is indicative of infective mastitis, (1) The diagnosis
of mastitis is important due to two reasons. Firstly,
it is the cause for reduction of milk production
and almost 25% of mothers avoid breast feeding
(4, 5) with subsequent influence on infants' health
(9). Secondly, mastitis increases the possibility
of infection transmission from mothers to their
infants. In Rotaviruses the risk of transmission
increases by two to four fold (10) and suggests
that mastitis may increase the risk of transmission
of HIV through breastfeeding (11)
Due to the importance and significant role of
mastitis in infant's heath, it seems necessary
to diagnose women with the signs of mastitis and
treat them urgently.
The aim of this study was to
determine the etiologic agent of mastitis in lactating
women and their antibiotic resistance pattern.
This study was carried out
on 203 milk samples of puerperal lactating women
hospitalized in Mirza kochakkhan hospital in Tehran
during the years 2003-04. Clinical findings of
mastitis were confirmed by the physician, in all
women. Before sampling, all women washed their
breasts with warm water, and their hands with
soap and water. The first few drops of their milk
was thrown away and 5ml of milk was collected
in sterile tubes afterwards. The samples were
immediately transported to the laboratory for
culturing and microscopic examination. The samples
were inoculated in different bacterial culture
media and were incubated at 37°c for 24 h.
The determination of isolated bacteria was done
by suitable biochemical tests and direct smear
(12). Drug sensitivity tests were performed by
disk diffusion method using a Muller Hinton agar.
From 203 samples, 26 samples
(12.8%) and 177 samples (87.2%) were positive
culture and negative culture respectively. From
26 samples with positive culture, 21 samples (80.8%)
were Coagulase Negative Staphylococcus (CNS) and
5 samples were Staphylococcus aureus. (Figure
1)
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Figure 1: Distribution of Bacteria in Mastitis in
Iranian Women
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Sensitivity and resistance
of isolated staphylococci to different antibiotics
were shown in Table 1. All strains of S.aureus
and Coagulase Negative Staphylococcus (CNS) were
sensitive to Cloxacillin, Fluxacillin and Dicloxacillin.
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Table 1: Drug Resistance
among Staphylococcus aureus and Coagulase
Negative Staphylococci (CNS) isolated from
mastitis in Lactating Women in Iran
|
|
Sample
|
S.aureus Resistance
|
*CNS Resistance
|
|
Number
|
Percent (%)
|
Number
|
Percent (%)
|
|
Amoxicillin
|
3
|
60
|
6
|
6/28
|
|
Tetracycline
|
2
|
40
|
5
|
8/23
|
|
Erythromycin
|
2
|
40
|
4
|
19
|
|
Azithromycin
|
2
|
40
|
4
|
19
|
|
Fluxacillin
|
0
|
0
|
0
|
0
|
|
Dicloxacillin
|
0
|
0
|
0
|
0
|
|
Cloxacillin
|
0
|
0
|
0
|
0
|
|
Cephalothin
|
3
|
60
|
3
|
3/14
|
|
Co- trimoxazole
|
4
|
80
|
8
|
1/38
|
*Coagulase
Negative Staphylococcus
In this study 203 milk samples
were taken from puerperal lactating women with
mastitis. 26 samples were positive culture. From
5 samples Staphylococcus aureus was isolated.
In numerous reports, Coagulase Negative Staphylococcus
aureus and Staphylococcus aureus were considered
as the most common factors of mastitis (2,7) similar
to our study. In investigations of Aabo et al
(13) and Matheson et al (14), the prevalence of
isolated Staphylococcus aureus in milk samples
of puerperal women with mastitis was higher than
in healthy women.
Bacteria are often found in
milk from asymptomatic breasts. The spectrum of
bacteria is often very similar to that found on
skin. Bacteriological studies are therefore complicated
by the difficulty of avoiding contamination from
skin bacteria (15). Thus the presence of bacteria
in the milk does not necessarily indicate infection,
even if they are not contaminants from the skin.
Fresh human milk is not normally a good medium
for bacterial growth. Cell counts and bacterial
colony counts are useful to distinguish between
infectious and non-infectious mastitis. In this
study we tried to provide proper conditions of
sampling, we asked mothers to wash their breasts
with warm water and wash their hands with water
and soap and let run the first few drops of milk,
the subsequent drops were collected in sterile
tubes.
According to W.H.O.'s reports, a sample of >106
leukocytes and > 103 bacteria /ml is an indication
of infective mastitis (1) therefore the colony
count of bacteria in this study was considered
and the samples with more than 103 bacteria were
assessed, but in 30 other samples the number of
colonies was less than 103 /ml. This observation
can be attributed to contamination of samples
with skin organisms.
Mastitis, if untreated, can lead to lactation
failure, recurrent mastitis, or breast abscess.
The early diagnosis and treatment of mastitis
may help prevent more serious suppurative infection,
recurrent mastitis, and other complications. In
a study recurrent mastitis developed in 13 patients
(10.2%) within a median of 24 weeks of follow-up
(16)
In our study all isolated Staphylococcus were
sensitive to Fluxacillin, Dicloxacillin, and Cloxacillin.This
means these antibiotics can be used for treatment
of mastitis but Erythromycin, Fluxacillin, Dicloxacillin,
Amoxicillin and Cephalothin were recommended for
the treatment of infective mastitis by WHO(1).
Our finding shows that most strains of isolated
bacteria were sensitive to Erythromycin and Azithromycin,
followed by Erythromycin and Tetracycline and
these antibiotics must be considered as first
stage in treatment of mastitis.
As mentioned, mastitis is common in various populations
and affects neonate's nutrition and neonatal health,
so prophylaxis of mastitis is an important matter
to be looked at in neonatal health. Proper methods
of lactation such as, close relation of mother
and neonate, suitable attachment of neonate to
the breast, and the frequency and duration of
lactation are among the best ways to prevent milk
stasis and infection.
If the infection occurs it should be diagnosed
and treated by suitable antibiotics such as Erythromycin,
Cephalothin and if necessary, by Cloxacillin or
their related antibiotics.
Antibiotic therapy must be used with suitable
methods of lactation to stimulate the milk evacuation.
The results of this survey indicated the role
of Staphylococcus aureus and Coagulase Negative
Staphylococcus in causing infective mastitis.
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