Between 2007 and 2009, 226 clinical strains of Streptococcus agalactiae, recovered from female genital specimens and from gastric fluid or ear specimens from infected newborns, were isolated at the Laboratory of Microbiology of Charles Nicolle Hospital of Tunis. They were investigated to determine the prevalence of antibiotic resistance and to characterize the mechanisms of resistance to macrolide and tetracycline. All strains were susceptible to penicillin, ampicillin and quinupristin–dalfopristin. They were resistant to chloramphenicol (3.1 %), rifampicin (19.1 %), erythromycin (40 %) and tetracycline (97.3 %); 3.1 % were highly resistant to streptomycin and 1.3 % to gentamicin. Among the erythromycin-resistant isolates, 78.7 % showed a constitutive macrolide–lincosamide–streptogramin B (MLSB) phenotype with high-level resistance to macrolides and clindamycin (MIC50 >256 µg ml−1), 10 % showed an inducible MLSB phenotype with high MICs of macrolides (MIC50 >256 µg ml−1) and low MICs of clindamycin (MIC50 = 8 µg ml−1) and 2.2 % showed an M phenotype with a low erythromycin-resistance level (MIC range = 12–32 µg ml−1) and low MICs of clindamycin (MIC range: 0.75–1 µg ml−1). All strains were susceptible to quinupristin–dalfopristin and linezolid (MIC90: 0.75 µg ml−1 for each). MLSB phenotypes were genotypically confirmed by the presence of the erm(B) gene and the M phenotype by the mef(A) gene. Resistance to tetracycline was mainly due to the tet(M) gene (93.1 %) encoding a ribosome protection mechanism. This determinant is commonly associated with the conjugative transposon Tn916 (P≤0.0002). tet(O) and tet(T) existed in a minority (2.2 % and 0.4 %, respectively). The efflux mechanism presented by tet(L) was less frequently present (4.5 %). No significant association was found between erm(B) and tet(M) genes.
Al-SweihN.,
JamalM.,
KurdiaM.,
AbduljabarR.,
RotimiV.2005; Antibiotic susceptibility profile of group B streptococcus (Streptococcus agalactiae) at the Maternity Hospital, Kuwait. Med Princ Pract 14:260–263 [View Article][PubMed]
AndrewsJ. I.,
DiekemaD. J.,
HunterS. K.,
RhombergP. R.,
PfallerM. A.,
JonesR. N.,
DoernG. V.2000; Group B streptococci causing neonatal bloodstream infection: antimicrobial susceptibility and serotyping results from SENTRY centers in the western hemisphere. Am J Obstet Gynecol 183:859–862 [View Article][PubMed]
BetriuC.,
CulebrasE.,
Rodríguez-AvialI.,
GómezM.,
SánchezB. A.,
PicazoJ. J.2004; In vitro activities of tigecycline against erythromycin-resistant Streptococcus pyogenes and Streptococcus agalactiae: mechanisms of macrolide and tetracycline resistance. Antimicrob Agents Chemother 48:323–325 [View Article][PubMed]
BingenE.,
DoitC.,
BidetP.,
BrahimiN.,
DeforcheD.2004; Telithromycin susceptibility and genomic diversity of macrolide-resistant serotype III group B streptococci isolated in perinatal infections. Antimicrob Agents Chemother 48:677–680 [View Article][PubMed]
CLSI2006; Performance Standards for Antimicrobial Susceptibility Testing; 16th Informational Supplement. M100-S16. Wayne, PA: Clinical and Laboratory Standards Institute;
CollinsT. S.,
CalderonM.,
GilmanR. H.,
VivarA.,
CharacheP.1998; Group B streptococcal colonization in a developing country: its association with sexually transmitted disease and socioeconomic factors. Am J Trop Med Hyg 59:633–636[PubMed]
de AzavedoJ. C.,
McGavinM.,
DuncanC.,
LowD. E.,
McGeerA.2001; Prevalence and mechanisms of macrolide resistance in invasive and noninvasive group B streptococcus isolates from Ontario, Canada. Antimicrob Agents Chemother 45:3504–3508 [View Article][PubMed]
De MouyD.,
CavalloJ. D.,
LeclercqR.,
FabreR.The Aforcopi-Bio Network2001; Antibiotic susceptibility and mechanisms of erythromycin resistance in clinical isolates of Streptococcus agalactiae: French Multicenter Study. Antimicrob Agents Chemother 45:2400–2402 [View Article][PubMed]
DecosterL.,
FransJ.,
BlanckaertH.,
LagrouK.,
VerhaegenJ.2005; Antimicrobial susceptibility of group B streptococci collected in two Belgian hospitals. Acta Clin Belg 60:180–184[PubMed][CrossRef]
DiPersioL. P.,
DiPersioJ. R.2006; High rates of erythromycin and clindamycin resistance among OBGYN isolates of group B Streptococcus.
. Diagn Microbiol Infect Dis 54:79–82 [View Article][PubMed]
FitoussiF.,
LoukilC.,
GrosI.,
ClermontO.,
MarianiP.,
BonacorsiS.,
Le ThomasI.,
DeforcheD.,
BingenE.2001; Mechanisms of macrolide resistance in clinical group B streptococci isolated in France. Antimicrob Agents Chemother 45:1889–1891 [View Article][PubMed]
FlannaganS. E.,
ZitzowL. A.,
SuY. A.,
ClewellD. B.1994; Nucleotide sequence of the 18-kb conjugative transposon Tn916 from Enterococcus faecalis
. Plasmid 32:350–354 [View Article][PubMed]
GonzalezJ. J.,
AndreuA.the Spanish Group for the Study of Perinatal Infection from the Spanish Society for Clinical Microbiology and Infectious Diseases2005; Multicenter study of the mechanisms of resistance and clonal relationships of Streptococcus agalactiae isolates resistant to macrolides, lincosamides, and ketolides in Spain. Antimicrob Agents Chemother 49:2525–2527 [View Article][PubMed]
HsuehP. R.,
TengL. J.,
LeeL. N.,
HoS. W.,
YangP. C.,
LuhK. T.2001; High incidence of erythromycin resistance among clinical isolates of Streptococcus agalactiae in Taiwan. Antimicrob Agents Chemother 45:3205–3208 [View Article][PubMed]
LopardoH. A.,
VidalP.,
JericP.,
CentronD.,
PaganiniH.,
FacklamR. R.,
ElliottJ.Argentinian Streptococcus Study Group2003; Six-month multicenter study on invasive infections due to group B streptococci in Argentina. J Clin Microbiol 41:4688–4694 [View Article][PubMed]
MatsubaraK.,
NishiyamaY.,
KatayamaK.,
YamamotoG.,
SugiyamaM.,
MuraiT.,
BabaK.2001; Change of antimicrobial susceptibility of group B streptococci over 15 years in Japan. J Antimicrob Chemother 48:579–582 [View Article][PubMed]
MoralesW. J.,
DickeyS. S.,
BornickP.,
LimD. V.1999; Change in antibiotic resistance of group B streptococcus: impact on intrapartum management. Am J Obstet Gynecol 181:310–314 [View Article][PubMed]
PortilloA.,
LanteroM.,
OlarteI.,
Ruiz-LarreaF.,
TorresC.2001; MLS resistance phenotypes and mechanisms in β-haemolytic group B, C and G Streptococcus isolates in La Rioja, Spain. J Antimicrob Chemother 47:115–116 [View Article][PubMed]
PoyartC.,
JardyL.,
QuesneG.,
BercheP.,
Trieu-CuotP.2003; Genetic basis of antibiotic resistance in Streptococcus agalactiae strains isolated in a French hospital. Antimicrob Agents Chemother 47:794–797 [View Article][PubMed]
RuessM.,
MüllerU.,
SanderA.,
BernerR.2000; Antimicrobial susceptibility patterns of Streptococcus agalactiae in a German university hospital. Scand J Infect Dis 32:623–626 [View Article][PubMed]
SahnounO.,
Ben AbdallahH.,
NoomenS.,
Ben Elhadj KhélifaA.,
MastouriM.2007; [Antimicrobial susceptibility of Streptococcus agalactiae strains in Monastir]. Med Mal Infect 37:734–737 (in French) [View Article][PubMed]
SchragS. J.,
ZywickiS.,
FarleyM. M.,
ReingoldA. L.,
HarrisonL. H.,
LefkowitzL. B.,
HadlerJ. L.,
DanilaR.,
CieslakP. R.,
SchuchatA.2000; Group B streptococcal disease in the era of intrapartum antibiotic prophylaxis. N Engl J Med 342:15–20 [View Article][PubMed]
SeppäläH.,
NissinenA.,
YuQ.,
HuovinenP.1993; Three different phenotypes of erythromycin-resistant Streptococcus pyogenes in Finland. J Antimicrob Chemother 32:885–891 [View Article][PubMed]
ShabayekS. A.,
AbdallaS. M.,
AbouzeidA. M.2009; Vaginal carriage and antibiotic susceptibility profile of group B Streptococcus during late pregnancy in Ismailia, Egypt. J Infect Public Health 2:86–90 [View Article][PubMed]
TraubW. H.,
LeonhardB.1997; Comparative susceptibility of clinical group A, B, C, F, and G β-hemolytic streptococcal isolates to 24 antimicrobial drugs. Chemotherapy 43:10–20 [View Article][PubMed]