title: Group A streptococcal infections in injection drug users in Barcelona, Spain: epidemiologic, clinical, and microbiologic analysis of 3 clusters of cases from 2000 to 2003.
abstract: An unexplained resurgence of Group A streptococci (GAS) infections has been observed since the mid-1980s in the United States and Europe, particularly among intravenous drug users (IDUs). Several risk factors have been identified. Mutations in the capsule synthesis regulator genes (csrRS) have been associated with an increase in virulence. From January 1998 to December 2003, we conducted a prospective and retrospective descriptive analysis of invasive GAS soft-tissue infections in IDUs in Barcelona, Spain. Clinical features were collected, and we conducted a surveillance study to identify risk factors associated with GAS soft-tissue infections. We analyzed chromosomal DNA by low cleavage restriction enzymes and used pulsed-field gel electrophoresis (PFGE) and variable gene sequence typing (VGST) of the emm gene to disclose the epidemiologic relationship between the strains. We analyzed the influence of clonality (M-type) and mutations in csrRS genes of these strains on clinical features. We identified 44 cases, all of which were grouped in 3 clusters: fall 2000, fall 2002, and fall 2003. Cellulitis with or without abscesses (75%) and fever (90.9%) were the most common clinical manifestations. Distant septic complications were infrequent (18.2%). Although all patients had severe infections (mainly bacteremic needle abscesses), their outcome with antibiotic therapy, usually beta-lactam, was successful in all cases. However, surgery was needed in 40.9% of patients. Through the surveillance study we found that infected patients had a higher number of drug injections per day (odds ratio [OR], 18.84; 95% confidence interval [CI], 4.83-79.4; p<0.00001), shared paraphernalia for drug use more frequently (OR, 11.11; 95% CI, 3.24-39.04; p<0.0001), were in a higher proportion both currently unemployed and homeless (OR, 4.22; 95% CI, 1.5-12.15; p<0.0001), were not in a methadone maintenance program (OR, 0.03; 95% CI, 0-0.19; p<0.00001), and more often bought drugs at a specific site (OR, 33.92; 95% CI, 7.44-174.93; p<0.00001) and from a specific dealer (OR, 72; 95% CI, 8-3090; p<0.00001), compared with patients not infected. The fall 2000 cluster was polyclonal, whereas the other 2 clusters were mainly due to the same strain of GAS (emm 25.2), and were defined as epidemic outbreaks. Clinically, the cases due to the clonal strain presented abscesses and needed surgery more frequently (p<0.001 and p=0.005, respectively). On the other hand, mutations in the csrRS genes were not associated with invasive GAS soft-tissue infection. There has been an increase in the number of cases of invasive GAS soft-tissue infections in IDUs in Barcelona, which seems to be related to drug users' habits and their socioeconomic status. Clonality (emm 25.2) but not mutations in the csrRS genes was associated with more severe GAS soft-tissue infections.
authors.affiliation: From Service of Infectious Diseases and Service of Microbiology, Hospital Clínic Universitari, Barcelona (JMS, P. Castro, GR, AL, MA, JMG, JV, FG); Infectious Disease Unit, Hospital del Mar, Barcelona (FS, JLLC); Service of Microbiology, Laboratori de Referència de Catalunya, El Prat de Llobregat (MS); Service of Infectious Diseases and Service of Microbiology, Hospital de Sant Pau, Barcelona (FM, ME, MAS, P. Coll); Service of Internal Medicine, Hospital Germans Trias i Pujol, Badalona (JR); and Service of Epidemiology, Agèencia de Salut, Barcelona (MTB, PGO, JAC), Spain.
authors.forename: Josep M
authors.initials: JM
authors.lastname: Sierra
authors.forename: Francesca
authors.initials: F
authors.lastname: Sánchez
authors.forename: Pedro
authors.initials: P
authors.lastname: Castro
authors.forename: Margarita
authors.initials: M
authors.lastname: Salvadó
authors.forename: Gloria
authors.initials: G
authors.lastname: de la Red
authors.forename: Agnes
authors.initials: A
authors.lastname: Libois
authors.forename: Manuel
authors.initials: M
authors.lastname: Almela
authors.forename: Francesca
authors.initials: F
authors.lastname: March
authors.forename: Montserrat
authors.initials: M
authors.lastname: Español
authors.forename: Maria Antonia
authors.initials: MA
authors.lastname: Sambeat
authors.forename: Joan
authors.initials: J
authors.lastname: Romeu
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Brugal
authors.forename: Patricia García
authors.initials: PG
authors.lastname: de Olalla
authors.forename: Jose Maria
authors.initials: JM
authors.lastname: Gatell
authors.forename: Jordi
authors.initials: J
authors.lastname: Vila
authors.forename: Felipe
authors.initials: F
authors.lastname: García
authors.forename: Jose Luís López
authors.initials: JLL
authors.lastname: Colomés
authors.forename: Joan A
authors.initials: JA
authors.lastname: Caylà
authors.forename: Pere
authors.initials: P
authors.lastname: Coll
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D016000:Cluster Analysis; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D004196:Disease Outbreaks; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D009154:Mutation; D011159:Population Surveillance; D011446:Prospective Studies; D015183:Restriction Mapping; D012189:Retrospective Studies; D012307:Risk Factors; D017422:Sequence Analysis, DNA; D018461:Soft Tissue Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D013030:Spain / Q000453:epidemiology; D013290:Streptococcal Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D015819:Substance Abuse, Intravenous / Q000150:complications / Q000453:epidemiology* / Q000382:microbiology; D047090:beta-Lactams / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams