Molecular characterization and antimicrobial susceptibility of hemolytic Streptococcus agalactiae from post-menopausal women
Introduction
Streptococcus agalactiae (group B streptococci, GBS) is the most common etiologic agent of neonatal sepsis [1]. Severe GBS infections are increasingly recognized in adults, mainly in the elderly and in individuals compromised by underlying medical conditions, with reported incidence rates ranging from 4.4 to 23 cases per 100,000 adults [2], [3], [4], [5].
The incidence is higher in patients over the age of 60 years. Primary bacteraemia is the most frequent form of invasive GBS disease, followed by skin and soft-tissue infection, pneumonia and urinary tract infections [3], [4], [5]. The prevalence of colonization reported among healthy elderly adults (20–25%) is similar to that among women of child-bearing age [3], [6].
The incidence of neonatal early onset GBS infections has nose-dived since the generalized use of intrapartum antibiotic prophylaxis in GBS-colonized pregnant women [7]. In contrast, there are no strategies to prevent GBS infection in infants aged over 7 days (late-onset GBS disease) or in adult patients [8], and several studies have reported an increase in the rate of GBS invasive infections among adults over the past few years [2], [9], [10].
The most promising approach for the prevention of GBS-induced invasive disease is the development of an effective vaccine to prevent infection not only in neonates but also in the elderly [4], [11], [12].
Numerous studies have analyzed the variability of colonization by GBS, but most have focused on pregnant women [13], and only a few have investigated the prevalence of colonization among non-pregnant adults [3], [6]. Investigation of the distribution of capsular serotypes and sequence types (STs) among GBS infection strains in neonates and pregnant women has revealed strong differences between these populations, suggesting that some GBS lineages are more prone to cause disease in neonates than in the women. Fewer data are available on the serotypes and MLSTs of strains colonizing the elderly and causing infections in this population. The objective of this study was to assess the GBS colonization rate and GBS antibiotic resistance profile in post-menopausal women in our area, using capsular serotyping and MLST to study possible correlations between capsular types and clonal complexes of GBS colonizing isolates.
Section snippets
Methods
The study was approved by the ethics committee of Virgen de las Nieves University Hospital in Granada (Southern Spain) in April 2010. Sample size calculation was performed to get a 3% accuracy, with a confidence interval 95% and assuming a prevalence of colonization GBS in adults 15% [14] Six hundred consecutive post-menopausal women attending the Emergency Department of the hospital for non-infectious conditions between March 2011 and February 2012 were enrolled in the study (none of them
Results
GBS were recovered from 107 (17.8%) out of the 600 vaginal-rectal specimens studied. The distribution of capsular types is shown in Table 1.
The most frequent types were Ia, III and V, which together accounted for 77.6% of strains. None of the isolates belonged to types VI, VII, VIII or IX. In one case (0.9%), the serotype of the strain could not be determined. The proportion of strains non-typeable by serological methods was not determined in our study, which exclusively used molecular capsular
Discussion
There has been little research on the prevalence of GBS colonization in post-menopausal women, which was found to be 17.8% in the present study, slightly higher than the prevalence of 15.9% detected in pregnant women in the same area between 2009 and 2011 [20].
The distribution of capsular types was similar in both population groups, with serotype III being the most frequent [20]. However, in comparison to the distribution generally reported in colonized pregnant women in Europe, we found a
Conflicts of interest
The authors declare no conflict of interest.
Funding
The authors declare funding received by University Hospital Virgen de las Nieves (Granada) in study design; in the collection, analysis and interpretation of data for this article.
References (34)
- et al.
Intrapartum antibiotic prophylaxis for the prevention of perinatal group B streptococcal disease: experience in the United States and implications for a potential group B streptococcal vaccine
Vaccine
(2013) - et al.
A multiplex PCR assay for the direct identification of the capsular type (Ia to IX) of Streptococcus agalactiae
J. Microbiol. Methods
(2010) - et al.
Serotypes and antibiotic resistance patterns in beta-hemolytic Streptococcus agalactiae isolates in colonized mothers and newborns with invasive disease
Enferm. Infecc. Microbiol. Clin.
(2015) - et al.
Epidemiology of Streptococcus agalactiae colonization in Germany
Int. J. Med. Microbiol.
(2006) - et al.
Molecular characterization and antimicrobial susceptibility profiles in Streptococcus agalactiae colonizing strains: association of erythromycin resistance with subtype III-1 genetic clone family
Clin. Microbiol. Infect.
(2010) - Edwards, M.S., Nizet, V., 2011. No Title. In: Remington, J.S., Klein, J.O. (Eds.), Wilson CB NV& MY, Infect. Dis. Fetus...
- et al.
Group B streptococcal disease in nonpregnant adults: incidence, clinical characteristics, and outcome
Eur. J. Clin. Microbiol. Infect. Dis.
(2004) - et al.
Group B streptococcal infections in elderly adults
Clin. Infect. Dis.
(2005) - et al.
Group B Streptococcus: global incidence and vaccine development
Nat. Rev. Microbiol.
(2006) - et al.
Group B Streptococcal colonization and serotype-specific immunity in healthy elderly persons
Clin. Infect. Dis.
Revisiting the need for vaccine prevention of late-onset neonatal group B streptococcal disease: a multistate, population-based analysis
Pediatr. Infect. Dis. J.
Clinical features of group B Streptococcus prosthetic joint infections and molecular characterization of isolates
J. Clin. Microbiol.
Emerging trends in invasive and noninvasive isolates of Streptococcus agalactiae in a Latin American hospital: a 17-year study
BMC Infect. Dis.
Prevention of group B streptococcal neonatal disease revisited. The DEVANI European project
Eur. J. Clin. Microbiol. Infect. Dis.
Relevance of age at diagnosis to prevention of late-onset group B streptococcal disease by maternal immunization
Pediatr. Infect. Dis. J.
Prevention of perinatal group B streptococcal disease—revised guidelines from CDC
MMWR Recomm. Rep.
Cited by (10)
Prevalence of group B streptococcal colonization in the healthy non-pregnant population: a systematic review and meta-analysis
2021, Clinical Microbiology and InfectionCitation Excerpt :This resulted in 6.6% (95% CI 5.1%–8.6%) of the participants in which GBS was not identified in the rectum, but in another site. Twenty-one studies (eight from Europe; seven from North America; four from Asia and one each from South America and Africa) reported data on the serotype distribution in the population that was eligible for this review (see Supplementary material, Table S4) [23,25,26,34,37,45,48,49,51,60–62,64,76,81,94,101,105]. Overall, serotype III was the most common serotype (312/1061; 29.4%), followed by II (239/1061; 22.5%), Ia (134/1061; 12.6%) and V (123/1061; 11.6%).
Genetic diversity and biofilm formation of invasive and noninvasive Streptococcus agalactiae isolates: Emergence of hypervirulent CC19 strains in Tehran, Iran
2023, Acta Microbiologica et Immunologica HungaricaCharacteristics of Streptococcus agalactiae causing urinary tract infections: Emergence of new sequence types ST74 and ST38 in Iran
2023, Iranian Journal of Basic Medical SciencesGroup B streptococcal colonization in elderly women
2021, BMC Infectious DiseasesMolecular Characterization of Streptococcus agalactiae Isolates from Pregnant Women in Kathmandu City
2020, Journal of Tropical Medicine