The accurate identification of the infecting species and the determination of its susceptibility to antimicrobial agents, given the large number of strains with atypical patterns, are crucial if patients with nocardiosis are to be successfully treated.

Acinetobacter baumannii is one of the major pathogens involved in nosocomial outbreaks. The clonal diversity of 729 epidemic strains isolated from 19 Spanish hospitals (mainly from intensive care units) was analyzed over an 11-year period. Pulsed-field gel electrophoresis (PFGE) identified 58 PFGE types that were subjected to susceptibility testing, rpoB gene sequencing, and multilocus sequence typing (MLST). All PFGE types were multidrug resistant; colistin was the only agent to which all pathogens were susceptible. The 58 PFGE types were grouped into 16 clones based on their genetic similarity (cutoff of 80%). These clones were distributed into one major cluster (cluster D), three medium clusters (clusters A, B, and C), and three minor clusters (clusters E, F, and G). Multidrug-resistant Acinetobacter baumannii is a bacterium frequently endemic in certain hospital wards and is responsible for numerous nosocomial outbreaks around the world (3,23,33). Its great capacity to survive in low-moisture environments and its ability to develop resistance to antimicrobial agents afford A. baumannii the possibility of spreading in hospitals. The skin, oropharynx, and digestive tract are the main body areas colonized in hospitalized patients. The risk of colonization and subsequent infection are associated with factors such as the presence of underlying severe illnesses, long-term hospitalization, stays in specific hospital wards, selective antimicrobial pressure, and invasive interventions such as the use of mechanical ventilation or catheters (4,12,14,18).Nosocomial outbreaks of A. baumannii can have their origin in a single reservoir or in multiple contaminated sites (37, 39), and infection can have serious repercussions for patient morbidity and mortality. Patients can acquire the bacterium from an environmental source or from other patients (6, 18).The clonal study of hospital strains is very important in terms of an understanding of the epidemiology of these outbreaks. The aim of the present work was therefore to analyze the genetic diversity and clonal distribution of epidemic strains of A. baumannii isolated from around Spain over a long period of time. Isolates collected during outbreaks at different hospitals were analyzed by pulsed-field gel electrophoresis (PFGE), sequencing of the RNA polymerase ␤ subunit (rpoB) gene, and multilocus sequence typing (MLST). The results were then compared. Antimicrobial susceptibility testing was also performed to determine the multidrug resistance phenotypes of these epidemic strains. MATERIALS AND METHODSBacterial strains. Over the 11-year period from 1997 to 2007, an initial 814 A. baumannii strains isolated from clinical settings and suspected of being involved in nosocomial outbreaks were sent to the Spanish National Center for Microbiology (CNM) for typing. Strains were isolated from 19 public hospitals in 17 Spanish provinces. Hospitals were coded H1 to H19, and provinces were coded P1 to P17. The type of clinical sample, the hospital ward of origin, and the isolation per...

Penicillin-resistant (penr) clinical isolates of Neisseria meningitidis, which do not produce beta-lactamase, were first identified in Spain in 1985; the frequency of their recovery, which has been increasing in the past few years, reached 20% in 1989. Serogrouping, determination of serotypes and subtypes, and multilocus enzyme electrophoresis of the penr strains showed an extensive diversity. Resistance is due, at least in part, to a decreased affinity of penicillin-binding protein (PBP) 2 for penicillin. Similar low-affinity forms of PBP 2 are also found in penr isolates of Neisseria lactamica, Neisseria polysaccharea, and Neisseria gonorrhoeae. Genetic transformation of an N. meningitidis type strain to low-level penicillin resistance with DNA from resistant meningococci and other Neisseria species resulted in transformants that possessed low-affinity forms of PBP 2. These altered forms of PBP 2 have been shown to arise from recombinational events that replace parts of the PBP 2 gene with the corresponding regions from the PBP 2 genes of commensal Neisseria species.