Molecular epidemiology of methicillin-resistant Staphylococcus aureus from different population groups in Argentina.

OBJECTIVES: In Latin America, methicillin-resistantStaphylococcus aureus (MRSA) is a leading cause of nosocomial infections. Limited studies have addressed the molecular epidemiology of MRSA clones in Argentina, characterised by continuous human migratory movements. The aim of this study was to describe the MRSA epidemiology, including distinct patient populations from different regions of the country. METHODS: MRSA strains were collected in epidemiological studies conducted from 2009 to 2015 in three cities (Formosa, Córdoba and Tucumán) and involving four population groups: community adult patients; hospitalised adults; hospitalised children; and healthy children (nasal colonisation). Antimicrobial susceptibility testing, SCCmec and Panton-Valentine leukocidin (PVL) typing, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were performed. RESULTS: A total of 120 MRSA isolates were recovered with an important population diversity in the groups studied; in community adult patients, MRSA isolates corresponded to ST5, ST267 and ST1619; from hospitalised adults they were ST97, ST5, ST72, ST125, ST200, ST647, ST747, ST935 and ST2941; from hospitalised children they were ST5, ST30, ST34, ST1163 and ST1619; and from colonised children they were ST5, ST125, ST34, ST100, ST1619, ST207 and ST1163. Results of SCCmec typing showed SCCmec I, SCCmec IIIA, SCCmec IV and SCCmec ND associated or not with PVL genes. CONCLUSIONS: MRSA genetic lineages have differing distribution in the three regions. The most prevalent was ST5 in colonisation, community and invasive settings. Here we describe ST34-SCCmec IV clone for the first time in the hospitalised paediatric population. These findings contribute to the understanding of epidemiological changes in recent years.

Virulence factors and clinical patterns of multiple-clone hypermucoviscous KPC-2 producing K. pneumoniae.

Carbapenemase-producing Klebsiella pneumoniae (CRKP) are increasingly reported worldwide being necessary the local epidemiological monitoring. Our aim was to characterize the hypermucoviscous CRKP isolates collected in our hospital during a 6 months period. Carriage of the carbapenemase genes (bla KPC, bla NDM, bla VIM and bla OXA-48), extended spectrum ß-lactamases (bla SHV-2, bla CTX-M) and the virulence genes (magA, k2A, rmpA, wabG, uge, allS, entB, ycfM, kpn, wcaG, fimH, mrkD, iutA, iroN, hly and cnf-1) were determined by multiplex-PCR. Genetic relationship among the isolates was performed by PFGE and MLST. A total of 35 isolates were recovered, being the urinary and respiratory tract the most common infection sites (34.2%). The bla KPC-2 gene was present in all the isolates, coexisting with bla CTX-M-2 (45.7%), bla SHV-2 (28.6%), and bla CTX-M-2/bla SHV-2 (14.3%). The capsular serotype K2 corresponded with 68.6% of the isolates. Virulence factors frequency were variable [adhesins (97.1%), siderophores (94.3%) and phagocytosis resistance (wabG 48.5%, uge 80% and ycfM 57.1%)]. A total of 10 STs were identified although 40% of them clustered on ST25-CC65, and 17% to ST17. The incidence of KPC-2-producing K. pneumoniae reported by the hospital was 0.290 per 1000 admissions. In summary we described an epidemic scenario of multidrug resistant hypermucoviscous KPC-2 producing ST25 K. pneumoniae in our institution.

[Detection, isolation and characterization of Shiga toxin-producing Escherichia coli (STEC) in fresh ground beef from butcher shops in Concepción, Tucumán Province]. / Detección, aislamiento y caracterización de Escherichia coli productor de toxina Shiga a partir de carne molida fresca proveniente de carnicerías de Concepción, provincia de Tucumán.

Shiga toxin-producing Escherichia coli is an emerging foodborne pathogen. There are many STEC serotypes associated with human diseases, being the O157:H7 serotype the most prevalent. Ground beef is the main transmission vehicle. In Concepción city, Tucumán Province, between September and December 2004, two hemolytic uremic syndrome (HUS) cases were diagnosed. The main objective of this work was to detect, isolate and characterize STEC O157 and non-O157 strains in fresh ground beef. Between September and December 2004, 53 fresh ground beef samples were collected from butcher shops in Concepción city. The USDA-FSIS (2002) methodology was used for detection, isolation and characterization of STEC O157:H7. Two PCR techniques for E. coli non-O157 detection and a previous intra-laboratory validated methodology for the isolation and characterization of these strains were used. The stx2 gen was identified in seven samples and the rfbO157 gene also in four of them. However, only one E. coli O157:H7 strain, biotype C, carrying the eae, stx2 and ehxA genes, was isolated. The present study shows the importance of implementing techniques for the detection of this emerging pathogen in meat samples.

A clinical and bacteriological study of children suffering from haemolytic uraemic syndrome in Tucuman, Argentina.

Haemolytic uraemic syndrome (HUS) is a disease with serious consequences for children, such as terminal chronic renal failure. During the last few years there have been numerous studies undertaken to determine whether there is a relationship between this disease and the presence of Shiga toxin-producing bacteria. Escherichia coli (E. coli) O157:H7 is one of the most frequent etiologic agents of HUS. It acts through cytotoxins called Shiga toxin 1 (Stx1) and/or Shiga toxin 2 (Stx2) and carries a 90-Kb plasmid codified for an adhesion fimbria which is part of its pathogenicity. The objectives of this study were to: 1). confirm whether there exists a relationship between severity and clinical presentation of HUS; 2). prove the existence of Stx1 and/or Stx2 in the faeces of HUS patients; and 3). detect the presence of Stx1- and/or Stx2-producing E. coli. Our results did not show any difference in the average age, sex or clinical behavior between children with diarrhea positive (D+) HUS and diarrhea negative (D-) HUS. Male patients were predominant, as was incidence during summer, considering all cases. Nor could we find any relationship between severity and HUS type. E. coli O157:H7 was isolated in 40% of the patients with (D+) HUS and in 50% of patients with (D-) HUS. Another serotype, O55:K59, was also isolated (7%). Stx1 and/or Stx2 were found in all HUS cases. The following virulence factors of E. coli strains isolated from 12 patients were found: Adhesion fimbria (100%), Stx1 (16%), Stx2 (32%), and Stx1 + Stx2 (50%). None of these factors was found in control patients. Sixty-three percent of the HUS cases showed seroconversion for lipopolysaccharides of E. coli O157. We drew the following conclusions: 1). there is no significant relationship between seriousness of HUS and type of disease; 2). an association exists between HUS and the production of Stx1 and Stx2; 3). the incidence of E. coli O157:H7 was high in Tucuman, Argentina; and 4). Stx2 alone or in association with Stx1 was the predominant toxin.

Association between hemolytic uremic syndrome and verotoxin-producing strains of E. coli.

One of the most frequent etiologic agents of Hemolytic Uremic Syndrome (HUS) is Escherichia coli O157H7, a microorganism that possesses virulence factors (Shiga-like Toxins I and II and adhesion fimbriae). The present study was set up to determine the relationship between HUS and the presence of Verotoxin in patients of "Niño Jesús" Children's Hospital. Tucumán, Argentina. 19 Children between 0 and 4 years old suffering from HUS (typical and atypical symptoms) and 15 control children of similar sex and age were selected. Presence of enterohemorrhagic E. coli was studied in both groups using molecular hybridization techniques. Free Verotoxin and Verotoxin-producing E. coli were analyzed in Vero cells. The following results were obtained: 1) The cytotoxic effect on Vero cells from fecal filtrates was observed in all children suffering from HUS 2) Verotoxin-producing E. coli was detected in only 12 of them 3) None of the filtrates of feces from control children presented a cytotoxic effect on Vero cells 4) In 8 of the patients suffering from HUS serotype O157H7 was isolated, in one O55K59 and in 3 typification of E. coli was not possible with the serums assayed 5) 77.5% of the strains isolated from HUS patients gave a positive molecular hybridization reaction, showing the following: Adhesion Fimbriae (AF) (25%); AF + Shiga-like Toxin I (13.75%); AF + Shiga-like Toxin II (20%); AF + Shiga-like Toxins I and II (41.25%). In patients suffering from atypical HUS a combination of AF + Shiga-like Toxins I and II was found. The 15 control children did not hybridize to the probes assayed. From the results obtained we may conclude that there exists a relationship between HUS and the presence of Verotoxin in the children suffering from HUS studied. The predominant serotype in our cases was O157H7 and Shiga-like Toxin II was found with highest frequency.