Phenotypic and molecular characterization of nosocomial K. pneumoniae isolates by ribotyping.

PURPOSE: To characterize clinical isolates of Klebsiella pneumoniae by phenotypic and genotypic methods. MATERIAL/METHODS: Over a 12-month period, 52 isolates of K. pneumoniae were isolated. Of these 52 isolates, 7 were isolated over a period of 21 days from a suspected outbreak in the Neonatal Intensive Care Unit (NICU) and 45 from sporadic cases occurring in different wards of hospital were analysed. RESULTS: The prevalence of K. pneumoniae isolates was 4% (52/1295). Quinolones, aztreonam and amikacin showed the greatest efficacy showing >85% sensitivity. Of the 52 isolates of K. pneumoniae, 8 (15.4%) isolates were positive for ESBL-production. Among the ESBL-producing K. pneumoniae, two out of 8 (25%) and 6 out of 8 (75%) were positive for (bla)SHV and (bla)CTX-M genes respectively. Ribotyping identified 30 distinct ribogroups among 52 isolates evaluated. Seven NICU outbreak isolates were divided into 2 ribotypes, as many as 6 belonged to one ribotype while one isolate which was isolated a week later was of a different ribotype, indicating the termination of the outbreak in the NICU. The outbreak in the NICU thus, was shown to have been caused by a single clone. CONCLUSIONS: A high discriminatory power, ease of interpretation coupled with excellent reproducibility and stability make ribotyping a very useful technique for investigating the molecular epidemiology of nosocomial infections caused by K. pneumoniae. A regular surveillance of hospital associated infections including monitoring antibiotic sensitivity pattern of K. pneumoniae, ESBL-production and molecular characterization is mandatory to control the spread of multidrug-resistant and ESBL-producing K. pneumoniae and for epidemiological purposes especially in outbreak situations.

Prevalence, antibiotic susceptibility pattern and production of extended-spectrum beta-lactamases amongst clinical isolates of Klebsiella pneumoniae at Armed Forces Hospital in Saudi Arabia.

The aim of this descriptive study was to determine the prevalence of Klebsiella pneumoniae from different clinical specimens, their antibiotic susceptibility pattern and the extended-spectrum beta-lactamase (ESBL) production among such isolates at Armed Forces Hospital, Al-Kharaj, Saudi Arabia, from November, 2004 to October, 2007. A total of 328 isolates of K. pneumoniae recovered from 8152 different specimens were studied for ESBL production and antimicrobial susceptibility. The prevalence of K. pneumoniae was 4% (328/8152). We observed a high percentage of K. pneumoniae resistant to ampicillin (100%) and tetracycline (92%). The prevalence of ESBL-producing K. pneumoniae was found to be 10.4% (34/328). The ESBL-producing strains were mostly from aspirates (25%) followed by sputum (20%) and blood (18.2%). These ESBLproducing isolates were highly resistant to gentamicin and ciprofloxacin. All isolates were susceptible to imipenem. Our findings demonstrate a high percentage of ESBL-producers among clinical isolates of K. pneumoniae and a high rate of multidrug resistance. Continued infection control measures and prudent use of antimicrobial agents are essential in reducing the spread of multi-resistant ESBL-producing K. pneumoniae.

The haemopoietic stem cell: between apoptosis and self renewal.

Self renewal and apoptosis of haemopoietic stem cells (HSC) represent major factors that determine the size of the haemopoietic cell mass. Changes in self renewal above or below the steady state value of 0.5 will result in either bone marrow expansion or aplasia, respectively. Despite the growing body of research that describes the potential role of HSC, there is still very little information on the mechanisms that govern HSC self renewal and apoptosis. Considerable insight into the role of HSC in many diseases has been gained in recent years. In light of their crucial importance, this article reviews recent developments in the understanding of the molecular, biological, and physiological characteristics of haemopoietic stem cells.

Molecular typing of Salmonella enterica serotype Worthington isolates from infantile diarrhoea.

BACKGROUND AND OBJECTIVES: Salmonella Worthington has been known to be a causative agent for childhood diarrhoea. There is a paucity of information on the molecular relatedness of the strains isolated in various hospitals in India. The present study was carried out to attempt molecular typing of a cluster of Salmonella Worthington isolates obtained from cases of infantile diarrhoea during a six month period, from a tertiary care paediatric hospital in Delhi, India. METHODS: Nine isolates of S. Worthington obtained from faecal samples of infants suffering from diarrhoea during October 2001 to March 2002, were identified by the conventional biochemical methods and by serotyping. The antimicrobial susceptibility was determined by the disk diffusion method. Molecular typing was done by ribotyping. RESULTS: Eight patients were admitted to 3 different wards of the hospital and one was an outpatient. Four patients including the first patient visited the hospital with diarrhoea as the presenting symptom while five developed diarrhoea after admission. Stool microscopy showed no specific findings. Salmonella Worthington was isolated from stool cultures of these patients. Repeated cultures of the common drinking water source of the hospital and the milk supplied to children from central kitchen were negative for known pathogens. All S. Worthington isolates were resistant to all the beta-lactams tested including third generation cephalosporins. Eight isolates were sensitive to furazolidone and 6 to ciprofloxacin. Molecular characterization by ribotyping revealed four different clones. INTERPRETATION AND CONCLUSION: As four different ribotypes of the isolated Salmonella Worthington isolates were identified, it was clear that there was no single source of infection.