Colonization with genital mycoplasmas in pregnant women and their neonates and birth weight

bl. Bakt. Hyg. A 265, 263-267 (1987)

Colonization with Genital Mycoplasmas in Pregnant Women and their Neonates and Birth Weight YASUO KANAMOTO I, HIROSHI NAKAN0 2 , TORU SUMII 2 , YOSHIY ASU MATSU0 3 , and HITOSHI KOTANI 4 1

Division of Microbiology, Hiroshima Prefectural Institute of Public Health Departments of Urol ogy 2 and Bacteriology 3, Hiroshima University School of Medicine, Hiroshima, Japan Institute for Medical Research, New Jersey 08103, USA

2,3

4

Received June 22, 1986 . Accepted November 17, 1986

Abstract The colonization by genital mycoplasmas of mothers and their newborn infants was examined in 114 pregnant women and their 84 neonates. Urine and cervical swabs were taken from the pregnant women in the last trimester, and urine from the neonates within six days after birth. Ureaplasma urealyticum was found in 73.7% of the pregnant women and in 17.9% of the neonates. Mycoplasma hominis was isolated in 8.8% of the material from the pregnant women and in 1.2% of that from the neonates. The isolation rate of U. urealyticum from newborn girls was significantly higher than that from newborn boys (p < 0.01). There was no correlation between the germ density in the urine of the pregnant women and that of the neonates. The urine of the neonates harboured as many U. urealyticum as that of the adults. The frequency of colonization by mycoplasmas in the pregnant women or the neonates was not related to the duration of gestation or the babies' birth weight.

Zusammenfassung 114 Schwangere und 84 Neugeborene wurden auf Besiedelung durch Genital-Mycoplasmen untersucht. 1m letzten Trimenon wurden bei den Schwangeren Urinproben gewonnen und Zervikalabstriche durchgefiihrr. Bei den Neugeborenen wurden die Urinproben innerhalb von 6 Tagen nach der Geburt gewonnen. Ureaplasma urealyticum wurde bei 73,7% der Schwangeren und 17,9% der Neugeborenen festgestellt. Mycoplasma hominis wurde bei 8,8% der Proben von den Schwangeren und 1,2% der Proben von den Neugeborenen isoliert. Der Anteil der Isolierungen von U. urealyticum war bei neugeborenen Madchen signifikant haher als bei neugeborenen Jungen (p > 0,01). Es bestand keine Korrelation zwischen der Keimdichte im Urin der Schwangeren und im Urin der Neugeborenen. Der Urin der Neugeborenen wies eine ebenso hohe Zahl an U. urealyticum auf wie der der Erwachsenen. Die Haufigkeit der Besiedelung durch Mycoplasmen bei den Schwangeren bzw. den Neugeborenen stand in keinem Zusammenhang mit der Schwangerschaftsdauer oder dem Geburtsgewicht der Siiuglinge.

264

Y. Kanamoto, H. Nakano, T. Sumii, Y. Matsuo, and H. Kotani

Introduction Several species of mycoplasmas including Mycoplasma hominis, Mycoplasma fermentans, Mycoplasma genitalium and Ureaplasma urealyticum can be isolated from the human genito-urinary tract. M. genitalium recovered from men with nongonococcal urethritis may have played a role in the genital tract infections (16, 17). M. hominis and U. urealyticum, being found commonly in the lower genital tracts, are acquired primarily through sexual contact (9) and transmitted to the infants at birth(3). M. hominis and U. urealyticum have been implicated in the pathogenesis of sexually transmitted diseases. M. hominis has been suspected to cause postpartum fever (19), abortion(5), pyelonephritis (15) and pelvic inflammatory disease (10). U. urealyticum has been reported to be associated with nongonococcal urethritis (14), chronic prostatitis(2) and low birth weight(6). The ability of U. urealyticum to cause premature delivery and low birth weight has been the subject of much controversy. Some investigators (1, 8, 13) found a correlation between genital colonization by U. urealyticum in pregnant women and low birth weight of the neonates, whereas others did not (4, 11, 12, 18). This study was designed to investigate the colonization by U. urealyticum and M. hominis in pregnant women and their neonates and to determine the association of these mycoplasmas, if any, with the birth weight of the neonates.

Materials and Methods

Subjects: The study population consisted of 114 randomly selected women, who visited a clinic of obstetrics and gynecology in Hiroshima during a period of 10 months beginning in June 1983, and their 84 neonates. The women were all housewives, ranging in age from 21 to 36 years (mean 26.7), and most of them belonged to the middle or upper social classes. All the neonates were delivered normally and in good health. Collection of specimens: Specimens of sterile cotton swabs from the endocervical canal and clean-catch midstream urine were obtained from the pregnant women in the last trimester. Urine specimens from the neonates were collected into a pediatric urine collector (Atom Co., Ltd., Japan) within six days after birth. Culture procedures: Isolation of mycoplasmas was simultaneously performed on agar and in broth; both A7 agar and T broth as modified by Kotani and Ogata (7) were used for U. urealyticum, and A7 agar and PPLO broth containing 1% arginine, for M. hominis. The swabs were immersed and rinsed in 1 ml of T broth immediately after having been taken. 0.2 ml of the swab suspension or urine was transferred into 1.8 ml of T broth and then 5 serial tenfold dilutions were prepared in T broth. 0.01 ml of each dilution was plated on A7 agar. 0.2 ml of T broth dilution was added to 2 ml of PPLO broth. All the tubes and plates were incubated at 37°C for 7 days. Daily observation was made for the colour change of the liquid media from yellow to reddish purple. When the colour change occurred, the culture was put into T broth or PPLO broth. The agar plates were examined for the development of colonies under a stereoscopic microscope at low-power magnification. Statistical analysis: The data obtained were analyzed by the chi-square test and Student's t-test. Results The isolation rate of U. urealyticum was 73.7% in the pregnant women and 17.9% in the neonates, and that of M. hominis was 8.8% and 1.2%, respectively. The mothen

Genital Mycoplasmas and Fetal Outcome

265

Table 1. Recovery of genital mycoplasmas from neonates No. (%) positive for Sex

No. examined

U. urealyticum

M. hominis

Male

54

o

Female

30

3 (5.6) 12 (40.0)J

Total

84

15 (17.9)

1 (1.2)

1 (3.3)

* p < 0.01

of the neonates from whom mycoplasmas were isolated had harboured the same species of the organism in the last trimester. Urine and cervical swabs from 78 women were taken at the same time, and 60 of them were positive for U. urealyticum and 7 were positive for M. hominis in both specimens. Sex distribution of, and isolation rates of mycoplasmas from, the neonates are shown in Table 1. The isolation rate of U. urealyticum was significantly higher in the females than that in the males (p < 0.01)..

Table 2. Distribution of the number of colour changing units per ml of U. urealyticum in pregnant women and neonates

U. urealyticum (CCU/ml) Specimen

No. examined

10

Woman

Urine Cervical swab

60 60

2 1

Neonate

Urine

15

o

1

102

103

10 4

~ 105

3 4

13 5

23 19

19 31

o

4

7

4

The number of colour changing units (CCU) per ml of mycoplasmas in the urine of 15 neonates and in the urine and cervical swabs of 60 pregnant women from whom U. urealyticum was isolated are shown in Table 2. It averaged 10 4 (from 10 3 to 10 5 ) CCUI ml in the urine of the neonates, 10 3 .9 (from 10 1 to 10 5 ) CCUlml in the urine of the pregnant women and 10 4 .3 (from 10 1 to 105 ) CCUlml in the cervical swabs of the pregnant women, respectively. The mean number of CCU/ml in the urine of 69 pregnant women whose neonates were negative for U. urealyticum was 10 3 .8 CCUlml, while that of mothers whose neonates were positive for the organism was 10 3.4 CCUI ml (data not shown). Table 3 shows that there is no correlation between colonization with mycoplasmas, gestational length and birth weight; i.e. we found no difference in gestational length or birth weight between the mothers or neonates who were colonized or those who were not. 18

Zbl. Bakt. Hyg. A 26511-2

266

Y. Kanamoto, H. Nakano, T. Sumii, Y. Matsuo, and H. Kotani

Table 3. Relationships between colonization of genital mycoplasmas and gestationallengtl or birth weight No. of patient

Culture

Gestationallength (weeks) Mean ± SD

Birth weight (g Mean ± SD

84 39.7 ± 1.2 3151 ± 388 30 39.5 ± 1.3 3171 ± 278 Woman ---------------------------------------------------------------------------------------------------------positive 10 39.9 ± 1.3 3154 ± 523 M. hominis negative 104 39.6 ± 1.2 3157 ± 345 .

positive

U. urealytlcum negative

. positive Neonate U. urealytlcum negative

15 69

39.4 ± 1.3 39.5 ± 1.2

3028 ± 261 * 3160 ± 321

* not significant Discussion This paper describes the effect of U. urealyticum on fetal growth, by quantitativ cultures of U. urealyticum of urine and cervical swabs from pregnant women, an urine from their neonates. The dissemination rate of U. urealyticum from pregnant women to their neonate was significantly higher for female neonates than for male neonates. These resul1 confirm those reported by Foy and associates (3), and are probably due to the diffe] ence of anatomical structures of the external genitalia between male and female. Ther was no correlation between the germ density of U. urealyticum in the urine of pregnar women and the dissemination rate to their neonates. It suggests that the disseminatio is affected more by the sex of the neonates than by germ concentration. However, n difference in germ density by the sex of neonates was found. Moreover, there was a average number of 10 4 CCUlml of U. urealyticum in the urine of neonates colonize with U. urealyticum: the same as that in the urine of the colonized pregnant womer High germ concentrations of up to 10 5 CCUlml of U. urealyticum were detected i only four urine specimens from neonates. However, all the colonized babies wer clinically asymptomatic, suggesting that quantitative culture of U. urealyticum in nec nates has little clinical significance. Reports (1, 6, 8,13) on the low birth weight of neonates caused by U. urealyticUl have dealt mainly with Negro and Caucasian babies. The different conclusions reache in these reports may reflect racial differences in the study populations. In the preser study, the relationship between U. urealyticum and the weight of neonates was invest gated for the first time in Japanese babies. In spite of the high recovery of U. urealJ ticum from the urine of pregnant women, U. urealyticum did not influence fetal growt and gestational length. In the comparison of U. urealyticum-colonized neonates wit non-colonized neonates, there was no difference in fetal growth and gestationallengd These data suggest that though U. urealyticum tends to be disseminated to femal neonates, this colonization having little or no pathological impact among Japanes babies.

Acknowledgments. This work was supported by a grant from Daido Seimei Social We

fare Foudation.

Genital Mycoplasmas and Fetal Outcome

267

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