Microflora of the cervix during normal labor and the puerperium

Bacterial vaginosis

Bacterial vaginosis (BV) is the most common of the vaginitides affecting women of reproductive age. It appears to be due to an alteration in the vaginal ecology by which Lactobacillus spp., the predominant organisms in the healthy vagina, are replaced by a mixed flora including Prevotella bivia, Prevotella disiens, Porphyromonas spp., Mobiluncus spp., and Peptostreptococcus spp. All of these organisms except Mobiluncus spp. are also members of the endogenous vaginal flora. While evidence from treatment trials does not support the notion that BV is sexually transmitted, recent studies have shown an increased risk associated with multiple sexual partners. It has also been suggested that the pathogenesis of BV may be similar to that of urinary tract infections, with the rectum serving as a reservoir for some BV-associated flora. The organisms associated with BV have also been recognized as agents of female upper genital tract infection, including pelvic inflammatory disease, and the syndrome BV has been associated with adverse outcome of pregnancy, including premature rupture of membranes, chorioamnionitis, and fetal loss; postpartum endometritis; cuff cellulitis; and urinary tract infections. The mechanisms by which the BV-associated flora causes the signs of BV are not well understood, but a role for H2O2-producing Lactobacillus spp. in protecting against colonization by catalase-negative anaerobic bacteria has been recognized. These and other aspects of BV are reviewed.

Vaginal colonization with Escherichia coli in healthy women. Determination of relative risks by quantitative culture and multivariate statistical analysis

The rate of vaginal colonization with Escherichia coli in 495 healthy women was 12% in a prospective study with use of selective media and semiquantitative culture techniques. Computer-assisted multivariate analysis revealed that vaginal E. coli was significantly associated with the menstrual phase of the cycle, prior use of antibiotics, use of diaphragm or cervical cap for contraception, history of previous urinary tract infection, and coisolation of Staphylococcus aureus that was positive for the toxic shock syndrome toxin-1 (p less than 0.05, multiple stepwise logistic regression analysis). No significant association was observed with tampon use or brand, other contraceptive methods, sexual activity, genital symptoms, recent vaginal infection, or other personal habits. Quantitative cultures obtained sequentially throughout the menstrual cycle in 12 unselected women confirmed higher E. coli counts in menstrual or midcycle samples compared to paired premenstrual specimens (p less than 0.05, Wilcoxon paired rank sign test). These data emphasize the hormonal and other host determinants in vaginal colonization by E. coli and may explain the high rate of vaginal E. coli (64%), in addition to toxicogenic S. aureus, in acute toxic shock syndrome and the higher incidence of urinary tract infection in women with diaphragm or cervical cap for contraception compared to other contraceptive methods.

Perinatal mortality associated with intrauterine infection due to pseudomonads

Pseudomonads are common causes of nosocomial infections but are rarely implicated in perinatal disease. In a retrospective autopsy study we found that 9% of all acute congenital bacterial infections were due to Pseudomonas species. Premature rupture of membranes occurred in half the cases and clinical maternal amnionitis in two-thirds. One case was apparently nosocomial in origin. No known risk factors were implicated in any other case. Seven infants were stillborn and two died within a few hours. Congenital pneumonia, funisitis, and chorioamnionitis were found at autopsy. Intrauterine infection due to the pseudomonads poses a serious problem that has not been previously recognized.

Haemophilus influenzae in genitourinary tract infections

Haemophilus influenzae was isolated in pure or predominant culture from genital specimens from nine females and two males. Four of the females had vaginitis, two had IUD-related endometritis, one had an incomplete septic abortion, and one had probable urethral syndrome. Two males had urethritis.

Premature rupture of the membranes and ascending infection

The association of premature rupture of the membranes (PROM) and ascending infection was investigated in 15 women. Bacteriological, histological and immunofluorescence methods were used to study infection at various levels in the birth canal. In most of the women the membranes as well as the placentae showed heavy bacterial invasion. Bacterial distribution within the membranes showed a choriodecidual preponderance. Ascending infection appears to follow the choriodecidual route and may be a primary pathogenetic event in many instances of PROM. The anaerobe Bacteroides fragilis, which is very infrequently isolated in normal pregnant women, was found in five out of 15 women. Two infants had congenital pneumonia caused by group B streptococci and Haemophilus influenzae respectively. The neonatal outcome with PROM may be influenced by the efficiency of the individual defence mechanisms including the antimicrobial capacity of amniotic fluid.

Vaginal colonization with resistant aerobic bacteria after antibiotic therapy for endometritis

To assess the effect of broad-spectrum antibiotic therapy upon vaginal colonization, we collected vaginal specimens for culturing at the end of therapy from 50 patients treated for postcesarean section endometritis. Infected patients had participated in a double-blind therapy protocol and had received either clindamycin plus gentamicin or cefamandole plus placebo. Repeat vaginal culturing was performed 6 weeks later. Similar vaginal specimens for culturing were collected from 25 control patients who also had undergone cesarean section but had not received antibiotics. Of 26 patients treated with cefamandole, 16 (62%) developed vaginal colonization with isolates resistant to that drug; of 24 patients treated with clindamycin-gentamicin, two (8%) developed isolates resistant to these agents (p less than 0.001). Among 25 control patients, there was only one isolate resistant to cefamandole and none resistant to clindamycin-gentamicin. Compared to controls, more antibiotic-treated patients developed isolates resistant to cefamandole (p = 0.001) and to clindamycin-gentamicin (p = 0.06). Colonization did not persist, and there were no late infections in this population.

Amniotic fluid activity against Bacteroides fragilis and group B streptococci

The antimicrobial capacity of amniotic fluid (AF) against B. fragilis, group B streptococci and Escherichia coli, the latter as a reference indicator, was investigated in samples from 30 patients. In order to study trimester as well as individual variations in the antibacterial activity, 10 individual samples from each trimester of pregnancy (AF1, AF2, AF3), were separately tested. With B. fragilis all trimester samples showed initial inhibition lasting for 8 h, the bacteria then regaining growth capacity in all AF1, and the majority of AF2 and AF3 specimens. However, 4 AF2 and 3 AF3 samples showed continued bacteriostatic activity for up to 24 h. Group B streptococci exhibited uninhibited growth in all trimester samples. The growth of E. coli in AF1 and AF2 was not inhibited, whereas in AF3 a temporary arrest was observed at 8 h, this being followed by growth to control levels at 24 h. The findings may explain the frequent isolation of B. fragilis from cases of septic abortions during the first trimester. Individual variation in the effectiveness of the antibacterial activity against B. fragilis in AF2 and AF3 may explain why this microorganism, which is often implicated in severe maternal and neonatal infections, is occasionally recovered from the mother's endocervix without signs of disease. The inefficacy of AF in defence against group B streptococci correlates well with the frequent isolation of these bacteria from cases of severe congenital infections associated with premature delivery.

The upper vaginal and cervical anaerobic flora in menopausal women

The upper vaginal and cervical bacterial flora, especially the anaerobic one which has a particular role in postoperative morbidity, was studied in 78 menopausal women between 48 and 78 yr of age. The aim of the present study was to compare the results obtained with those reported for bacterial flora in women of other age groups. The patients were divided into the following 3 groups. (I) Twenty-eight healthy women with a natural menopause; (II) 30 women, 2-6 mth after surgical menopause due to panhysterectomy; and (III) 20 menopausal women 3 mth after vaginal hysterectomy. 30.7% of the cultures were found to be sterile. The anaerobic bacteria, developed only in the presence of aerobic germs, represented 11.5% of the total number of cultures and was found to be formed by Streptococcus bacteroides sp. and Bacteroides fragilis. The vaginal flora of menopausal women is not different from that found in children, young women, in pregnancy or postpartum. The anaerobic germs isolated in our study are normal inhabitants of the vagina and cervix which may occasionally become pathogens.

Study of the usefulness of clinical and hematologic findings in the diagnosis of neonatal bacterial infections

The purpose of this study was to evaluate the usefulness of clinical and hematologic findings in distinguishing infected from uninfected newborn infants. Of 356 evaluations for infections, 22 (6%) infants were found to have bacterial isolates. Eight of the 52 clinical and historical findings evaluated were found to be statistically associated with infection. Clinical findings of tachypnea/arrhythmia, decreased peripheral perfusion, pallor, hypo- or hyper tension, abdominal distention, irritability, lethargy, and apnea were signifi cantly associated with positive bacterial cultures. Laboratory data found to be significantly associated with infected infants included white blood cell count < 10,000 or ≥20,000/mm 3, absolute neutrophil count < 1,000/mm3, absolute band count > 200/mm3, and neutrophil band forms/mature neutrophils ≥ 0.10. A 5-point scoring system was derived from the data obtained from this study consisting of: ≥ 2 systems involved on clinical assessment; white blood cells < 10,000 or ≥20,000/mm 3; absolute neutrophils < 1,000/mm3; bands/mature neutrophils ≥ 0.10; and age > 1 week. The restrospective use of this scoring system revealed that all infants with life-threatening bacterial infections had three or more of these findings present. All infants suspected of bacterial disease, therefore, who score ≥ 3 points using this system should have antibiotic therapy started and continued until all cultures are negative. In the face of other strong clinical or laboratory evidence of infection, antibiotics should be begun following appropriate cultures, in spite of a low score. So used, the scoring sys tem described can be helpful to clinicians in making decisions concerning newborn infants suspected of bacterial infections.

Adherence of bacteria to vaginal epithelial cells at various times in the menstrual cycle

Adherence of vaginal isolates of Escherichia coli, Lactobacillus species, group B streptococci, Gardnerella vaginalis and Neisseria gonorrhoeae to exfoliated vaginal epithelial cells was studied in 10 healthy, sexually active medical students. Studies were done pre- and postmenstrually and at midcycle for two consecutive menstrual cycles. The mean number of adherent bacteria per vaginal epithelial cell (range) was 3.4 (0 to 14) for E. coli, 60.5 (12 to 152) for Lactobacillus species, 54.8 (21 to 76) for group B streptococci, 67.4 (15 to 161) for G. vaginalis, and 58.9 (15 to 186) diplococci for N. gonorrhoeae. Adherence of G. vaginalis increased with increasing acidity of the test medium (pH 4 to 8). There were no significant differences in adherence to vaginal epithelial cells obtained at the various times in the menstrual cycle for any of the organisms (p greater than 0.05). The pattern and extent of adherence among the women was similar for each organism. In this in vitro model, adherence characteristics did not vary with the menstrual cycle.

Aerobic and anaerobic urethral flora of healthy females in various physiological age groups and of females with urinary tract infections

We characterized the aerobic and anaerobic urethral flora of healthy females in three physiological age groups (premenarcheal, reproductive, and postmenopausal) and of females with urinary tract infections. The mean number of species per sample was 6.5, 7.7, and 10.3 for each of the physiological age groups, respectively, and 6.5 for the urinary tract infection group. Marked quantitative changes were seen with age and disease. Aerobes accounted for 65.6 and 73.8% of the flora of the premenarcheal and reproductive age groups, respectively, whereas anaerobes were dominant in the postmenopausal age group, accounting for 65.5% of the flora. Aerobic gram-negative rods were not isolated from any of the premenarcheal or reproductive-age subjects. Of the 10 postmenopausal subjects, 5 carried aerobic gram-negative rods, but these organisms accounted for only 1% of the flora. In contrast, they constituted 95% of the urethral flora of the urinary tract infection group. Bacteroides melaninogeneicus was commonly isolated and was the dominant isolate in the postmenopausal age group. Bacteroides fragilis was recovered from 7 of the 10 postmenopausal subjects, but these organisms constituted only 3% of the total flora. The factors responsible for the changes in urethral flora with age remain to be determined.

Anaerobic bacterial meningitis

Anaerobic meningitis occurred in four patients in whom anaerobic bacteria had not been suspected as a possible cause. The predisposing conditions were typical of those seen in patients previously reported to have this infection and included chronic otitis media with mastoiditis, chronic sinusitis, recent craniotomy and abdominal trauma. Two of the patients had undergone immunosuppression (immunosuppressed patients); a compromised immune system may facilitate the development of anaerobic meningitis in patients with the appropritate underlying conditions. Head and neck neoplasms, head trauma, suppurative pharyngitis and laminectomy wounds are additional situations in which anaerobic meningitis occurs. Anaerobic bacterial meningitis probably occurs more often than is recognized. The cerebrospinal fluid should be transported and cultured anaerobically when meningitis develops in a patient with a predisposing condition.