Serogroup C meningococci in Italy in the era of conjugate menC vaccination.
BACKGROUND
To assess changes in the pattern of Invasive Meningococcal Disease (IMD) in Italy after the introduction of conjugate menC vaccine in the National Vaccine Plan 2005-2007 and to provide information for developing timely and appropriate public health interventions, analyses of microbiological features of isolates and clinical characteristics of patients have been carried out. In Italy, the number of serogroup C meningococci fell progressively following the introduction of the MenC conjugate vaccine, recommended by the Italian Ministry of Health but implemented according to different regional strategies.


METHODS
IMD cases from January 2005 through July 2008 reported to the National Meningococcal Surveillance System were considered for this study. Serogrouping and sero/subtyping were performed on 179 serogroup C strains received at the National Reference Laboratory of the Istituto Superiore di Sanità. Antibiotic susceptibility testing was possible for 157 isolates. MLST (Multilocus sequence typing), porA VRs (Variable Region) typing, PFGE (Pulsed Field Gel Electrophoresis), VNTR (Variable Number Tandem Repeats) analyses were performed on all C:2a and C:2b meningococci (n = 147), following standard procedures.


RESULTS
In 2005 and 2008, IMD showed an incidence of 0.5 and 0.3 per 100,000 inhabitants, respectively. While the incidence due to serogroup B remained stable, IMD incidence due to serogroup C has decreased since 2006. In particular, the decrease was significant among infants. C:2a and C:2b were the main serotypes, all C:2a strains belonged to ST-11 clonal complex and all C:2b to ST-8/A4. Clinical manifestations and outcome of infections underlined more severe disease caused by C:2a isolates. Two clusters due to C:2a/ST-11 meningococci were reported in the North of Italy in December 2007 and July 2008, respectively, with a high rate of septicaemia and fatal outcome.


CONCLUSIONS
Public health surveillance of serogroup C invasive meningococcal disease and microbiological/molecular characterization of the isolates requires particular attention, since the hyper-invasive ST-11 predominantly affected adolescents and young adults for whom meningococcal vaccination was not recommended in the 2005-2007 National Vaccine Plan.
Stefanelli
Paola
P
Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Rome, Italy. paola.stefanelli@iss.it
Fazio
Cecilia
C
Sofia
Tonino
T
Neri
Arianna
A
Mastrantonio
Paola
P
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005798:Genes, Bacterial; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007558:Italy / Q000453:epidemiology; D008589:Meningococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D018598:Minisatellite Repeats; D038542:Neisseria meningitidis, Serogroup C / Q000145:classification* / Q000235:genetics*; D012703:Serotyping; D055815:Young Adult
APMIS. 2000 Jul-Aug;108(7-8):509-16
11167547
Euro Surveill. 2009 Apr 23;14(16):
19389338
Epidemiol Infect. 1999 Oct;123(2):193-200
10579437
Clin Microbiol Infect. 2007 May;13(5):550-2
17378929
Euro Surveill. 2004 Jul;9(7):11-5
15318008
FEMS Microbiol Rev. 2007 Jan;31(1):97-100
17147689
Med J Aust. 2007 Feb 5;186(3):108-9
17309394
J Infect Dis. 1993 Jun;167(6):1320-9
8501321
Lancet. 2002 May 25;359(9320):1829-31
12044380
J Clin Microbiol. 2005 Apr;43(4):1699-705
15814988
Diagn Microbiol Infect Dis. 1995 Aug;22(4):309-14
8582134
Epidemiol Infect. 1999 Dec;123(3):349-57
10694145
Antimicrob Agents Chemother. 2007 Aug;51(8):2784-92
17517841
JAMA. 1995 Feb 1;273(5):390-4
7823384
Proc Natl Acad Sci U S A. 1998 Mar 17;95(6):3140-5
9501229
J Clin Microbiol. 2003 Dec;41(12):5783-6
14662983
Antimicrob Agents Chemother. 1990 Aug;34(8):1523-8
2121092
Vaccine. 2007 May 22;25(21):4125-9
17449149
FEMS Microbiol Rev. 2007 Jan;31(1):101-7
17168998
APMIS. 1998 May;106(5):505-25
9674888
J Med Microbiol. 2002 Sep;51(9):717-722
12358061
Clin Microbiol Infect. 2007 Jan;13(1):100-3
17184297