Scand J Infect Dis 32: 339 – 340, 2000
SHORT COMMUNICATION
Serotypes and Antimicrobial Susceptibility of Group B Streptococcus Isolated from Neonates in Casablanca
RAJAA AITMHAND, NAJAT MOUSTAOUI, HOURIA BELABBES, NAIMA ELMDAGHRI and MOHAMED BENBACHIR
From the Microbiology Laboratory,IbnRochd Uni6ersity Hospital,Casablanca,Morocco
The serotypes and the levels of antibiotic resistance of 59 Streptococcus agalactiae isolates from neonates in Casablanca, from February 1992 to July 1997, were studied. Most of the isolates (86.4%) were recovered from early-onset disease. The serotype distribution was as follows: serotype III 39%; serotype Ia 32.2%; and serotype V 10.2%. All strains were susceptible to penicillin G, cefotaxime and ampicillin, whereas 1 strain was resistant to erythromycin. No high level of resistance to gentamicin was detected. A vaccine should comprise the most prevalent serotypes and also provide protection against serotype V disease. The antibiotic susceptibility patterns reported here support the recommended treatment and prophylaxis of invasive group B Streptococcal disease.
M.Benbachir,Microbiology laboratory,Faculte´ de Me´decine,BP9154Casablanca,Morocco
INTRODUCTION
Streptococcus agalactiae or group B streptococcus (GBS) is a major agent of neonatal infections (1). There is little information available on invasive GBS infection in Africa (2 – 4).
Recommendations for prevention of group B streptococ- cus infections have been published (5). Important changes in the serotype distribution have been reported recently with the emergence of serotype V (6). There are few recent data on susceptibility patterns of GBS.
We report here on the serotypes and antimicrobial sus- ceptibilities of Streptococcus agalactiae responsible for neonatal infections in Casablanca, Morocco.
MATERIALS AND METHODS
From February 1992 to July 1997, GBS was isolated from 59 neonates with invasive disease, admitted to the IbnRochd Univer- sity Hospital of Casablanca. A total of 52 isolates were recovered from blood and 7 from cerebrospinal fluid (CSF). Only 1 isolate per patient was studied. Children were considered to have very early-onset disease if their infection occurred during the first 24 h of life, early-onset disease (EOD) if it occurred during the first 7 ds of life and late-onset disease (LOD) if it occurred between the ages of 1 week and 3 months. Identification of strains as GBS was based on Gram-stained smear and production of beta-haemolysis on sheep blood agar. The confirmation was made by detection of group polysaccharide with latex particles coated with group-spe- cific antibodies (Slidex strepto- Kit, Biome´rieux, France).
Serotyping was done by latex agglutination (7). These reagents detected Ia, Ib, II, III, IV and V serotypes.
Antimicrobial susceptibility testing was performed by the agar dilution method in Mueller-Hinton agar with 5% defibrinated sheep blood according to recommended methods (8). The follow- ing antimicrobial agents were tested: penicillin G, ampicillin, cefo- taxime and erythromycin. The breakpoints used were those recommended by the National Committee for Clinical Laboratory Standards (8). High-level resistance (500mg/ml) to gentamicin was
determined by the dilution screen test (8). In each run, Enterococ- cus faecalis ATCC 29212 was included as quality control.
Data entry and analysis were carried out with Epi Info 5. For analysis two-tailed Fisher’s exact test was used and a p value B0.05 was considered statistically significant.
RESULTS
Most cases (86.4%) of the present study had early-onset and 64.4% of the 59 cases very early-onset disease. Eight neonates of 59 (13.6%) had late-onset disease. Of the 51 neonates with EOD, 92.2% had septicaemia and 7.8% had meningitis. Three of 8 neonates with LOD had meningitis.
Meningitis was significantly more often associated with LOD than with EOD (p= 0.046). Serotype III and serotype Ia were by far the most frequent (Table I). Serotype V was detected only in early-onset disease. This serotype repre- sented 10.2% of the total and 11.8% of the EOD serotypes.
Non-typeable isolates accounted for 5.1% of the GBS iso- lates and were found only in LOD.
All isolates were susceptible to penicillin G (MIC 905 0.03 mg/l), ampicillin (MIC 905 0.12 mg/l) and cefotaxime (MIC 905 0.06 mg/l), and all except 1 to erythromycin (MIC 905 0.25 mg/l). No high level of resistance to gen- tamicin was detected.
DISCUSSION
Most studies show that 75 – 80% of neonatal GBS infections are EOD (5, 6). In our series the percentage of EOD was 86.4% and the majority of cases of EOD occurred during the first hours of life (B 24 h), suggesting that neonates were colonized via the birth channel during delivery.
The distribution of serotypes among our isolates is in accordance with the literature with a predominance of type
© 2000 Taylor & Francis. ISSN 0036-5548 Scand J Infect Dis Downloaded from informahealthcare.com by Michigan University on 10/27/14 For personal use only.
Scand J Infect Dis 32
R.AitMhand et al.
340
Table I.Distribution of59group B Streptococcus serotypes according to the onset of the disease Serotypes (number of isolates)
Ia
Time of onset Ib II III IV V Non-typeable Total
2 17 3
Very early 11 5 38
Early 5 2 4 1 1 13
2
3 3
Late 8
2 2 23 4 5 3
Total 19 59
3.4 3.4 39 6.8 10.2 5.1
32.2 100
%
III, which is the most common serotype, followed by type Ia (7, 9). Types Ib and II are less frequently observed.
Serotype V has recently been reported as a significant cause of neonatal sepsis (6). In our series this serotype accounted for 10.2% of the cases, which was similar to 11.1% of isolates reported in Atlanta (6) and 11.2% in Maryland, USA (9). In Casablanca, types III, Ia and V accounted for 81.4% of GBS isolates. This percentage is similar to that reported recently (6, 9) suggesting that an effective capsular polysaccharide vaccine preparation should be multivalent and would also provide protection against serotype V disease.
Recent susceptibility data of GBS are rare. All our GBS isolates were susceptible to penicillin, ampicillin and cefo- taxime. These results are similar to those of a previous study (10). However, penicillin tolerance in clinical strains has been reported and this finding was linked to treatment failure in patients with serious GBS infections (11). Intermediate resistance to this antibiotic has also been identified (11). In another report, the percentage of resistance to penicillin was more important (12). The rate of resistance to erythromycin found in our strains (1.7%) was lower than that in other reports (10, 11). This drug may be used as an alternative for patients who are allergic to penicillin (5). Penicillin G is the drug of choice for intrapartum chemoprophylaxis and is preferred over ampicillin because of its narrow spectrum and a lower selective pressure (5). The recommended treatment of infants with invasive GBS disease is an association of penicillin or ampicillin plus an aminoglycoside (1). The susceptibility patterns of our isolates support these recom- mendations.
The serotype distribution is changing and susceptibility to antibiotics of GBS is variable depending upon geographic location. Indeed, continuous surveillance of GBS strains is important to provide data for vaccine formulation, for antibiotic prophylaxis and for treatment recommendations.
ACKNOWLEDGEMENTS
We thank Dr P. Geslin (French Reference Laboratory for Pneu- mococcus Creteil, France) for the reagents provided for serotyping of the strains.
REFERENCES
1. American Academy of Pediatrics. Group B streptococcal in- fections. In: Peter G. ed. Red book: Report of the commit- tee on infectious diseases. 23rd edn. Grove Village, IL: ELK, 1994: 439 – 442.
2. Cisse´ MF, Sow AI, Ba M, Ouangre AR, Samb A. Bacte´ri- ologie des septice´mies ne´onatales a` Dakar. Presse Med 1992;
21: 413 – 6.
3. Guediche MN, Frih S, Bchir A, Ayeche R, Abroug S. Rad- houane M. Profil bacte´riologique des infections materno- fœtales en Tunisie. Med Mal Infect 1989; 19: 23 – 7.
4. Benomar S, Lahbabi MS, Belabbes H, ElMouatassim S, ElMdaghri N, Benbachir M. Infection ne´onatale a` Strepto- coque du groupe B a` Casablanca (Maroc). Med Mal Infect 1998; 28: 932 – 6.
5. Centers for Disease Control and Preventation. Prevention of perinatal group B streptococcal disease: a public health per- spective. MMWR 1996; 45 Nb. RR-7.
6. Blumberg HM, Stephens DS, Modansky M, Erwin M, Elliot J, Facklam RR, et al. Invasive group B streptococcal dis- ease: the emergence of serotype V. J Infect Dis 1996; 173:
365 – 73.
7. Geslin P, Sissia G, Jelinkova J, Fremaux A, Motlova J.
Serotype distribution of group B Streptococci isolated from human source in France over a 10-year period (1980 – 1989).
New perspectives on streptococci and streptococcal infec- tions. Zentralbl Bakt 1992; Suppl 22: 484 – 5.
8. National Committee for Clinical Laboratory Standards.
Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically, 4th edn. Approved standard.
NCCLS document M7-A4. Wayne, Pennsylvania: NCCLS, 1997.
9. Harrison LH, Elliot JA, Dwyer DM. Serotype distribution of invasive group B Streptococci isolates in Maryland. Impli- cations for vaccine formulation. J Infect Dis 1998; 177: 998 – 1002.
10. Uh Y, Jang IH, Yoon KJ, Lee CH, Kwon JY, Kim MC.
Colonization rates and serotypes of group B Streptococci isolated from pregnant women in a Korean tertiary hospital.
Eur J Clin Microbiol Infect Dis 1997; 16: 753 – 6.
11. Betriu C, Gomez M, Sanchez A, Cruceyra A, Romero J, Picazo JJ. Antibiotic resistance and penicillin tolerance in clinical isolates of group B streptococci. Antimicrob Agents Chemother 1994; 38: 2183 – 6.
12. Kago I, Ndayo-Wouafo M, Tchokoteu PF, Tetanye E, Ti- etch F, Doumbe P. Infection ne´onatale a` Streptocoque du group B a` Yaounde´ (Cameroun). Ann Pediatr 1992; 39:
583 – 7.
Submitted April
