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Linked Article: Caselli et al. Br J Dermatol 2020; 183:784–785. [ABSTRACT FROM AUTHOR]

Abstract. The epidemiology of bacterial pathogens causing bloodstream infection was studied in 16 hospitals in Lombardy (northern Italy) over a 2-year period (1999 and 2000). Overall, 2,924 microorganisms causing significant bacteremia were collected. The most frequent isolates were Escherichia coli (n=663; 22.7%), Staphylococcus aureus (n=534; 18.3%), Staphylococcus epidermidis (n=242; 8.2%), and Pseudomonas aeruginosa (n=176; 6.0%). Unlike Escherichia coli, which was usually acquired from the community, Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa were usually acquired in hospitals. Rates of resistance to oxacillin and its associated traits were significantly higher among hospital-acquired staphylococci as compared to those of isolates from the community. Escherichia coli was highly susceptible to extended-spectrum cephalosporins, with a very low percentage of strains producing extended-spectrum ß-lactamases (ESBLs). On the contrary, production of ESBL appeared to be an important mechanism of resistance among nosocomial isolates of Klebsiella pneumoniae. Resistance to ciprofloxacin was widespread in several members of the family Enterobacteriaceae, with rates often exceeding 10%. Moreover, with regard to ciprofloxacin, there were no significant differences between rates of resistance among Enterobacteriaceae causing hospital-acquired infections versus those causing community-acquired infections. Multidrug resistance was commonly observed in Pseudomonas aeruginosa, indicating the need for new antimicrobial agents that are more active against nonfermentative gram-negative bacteria. In conclusion, epidemiological studies of the prevalence and antimicrobial susceptibility patterns of blood isolates in northern Italy appear to provide useful information for both empirical treatment of suspected infections and better management of patients. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate the production of extended-spectrum β-lactamases (ESβLs) and the epidemiological correlations in a total of 107 Klebsiella pneumoniae strains resistant to third- and fourth-generation cephalosporins. The strains were collected from patients in four intensive care units (3 neonatal and 1 general) in three hospitals in Italy between March 1996 and July 1997. All strains were found to produce ESβLs. Phenotypic (antibiotyping and ESβL patterns) and genotypic (plasmid profile and pulsed-field gel electrophoresis) analyses showed that a single strain had been responsible for each outbreak in each of the four intensive care units. Isoelectric focusing, activity on substrates and gene sequencing showed that the strains produced SHV-5, SHV-2a, SHV-12 and TEM-52 β-lactamases. This is not only the first time that ESβL-producing Klebsiella pneumoniae strains have been reported as causing epidemics in Italian hospitals, it is also, to the best of our knowledge, the first time that an outbreak caused by a TEM-52 ESβL-producing Klebsiella pneumoniae strain has been reported. The data presented here illustrate the complexity of determining the epidemiological pattern of ESβL producers in large hospitals that do not have an ESβL-monitoring program. [ABSTRACT FROM AUTHOR]

An outbreak of Serratia marcescens involving 42 patients admitted to the general intensive care unit of the Hospital of Varese, Italy, occurred from March 1994 to August 1995. The causative strains were resistant to oxyimino-cephalosporins and monobactams due to their production of an extended-spectrum β-lactamase. Another outbreak caused by Serratia marcescens strains had occurred in the same unit a few months earlier, from February to October 1993, with the strains involved producing a novel TEM-derived extended-spectrum β-lactamase. In order to verify whether there were any relationships between isolates from the two epidemics, the strains and their enzymes were characterized. Biochemical data and gene amplification experiments showed that the isolates of the second outbreak harbored a non-conjugative plasmid of approximately 48 kb, codifying for the production of an SHV-derived extended-spectrum β-lactamase with pI 8.2. Restriction fragment length polymorphism analysis of total genomic DNA by pulsed-field gel electrophoresis of Serratia marcescens isolates unambiguously identified two different bacterial clones responsible for the two epidemics. Epidemiological and microbiological investigations demonstrated the long persistence of Serratia marcescens strains and their circulation in other hospital wards, thus suggesting their possible role as a long-term reservoir for further epidemic spread. [ABSTRACT FROM AUTHOR]