High rate of colistin resistance among patients with carbapenem-resistant Klebsiella pneumoniae infection accounts for an excess of mortality.

Carbapenem-resistant Klebsiella pneumoniae (CR-KP) is becoming a common cause of healthcare-associated infection in Italy, with high morbidity and mortality. Prevalent CR-KP clones and resistance mechanisms vary between regions and over time. Therapeutic approaches and their impact on mortality have to be investigated. We performed a prospective study of patients with CR-KP isolation, hospitalized in nine hospitals of Rome, Italy, from December 2010 to May 2011, to describe the molecular epidemiology, antibiotic treatment and risk factors for mortality. Overall, 97 patients (60% male, median age 69 years) were enrolled. Strains producing blaKPC-3 were identified in 89 patients, blaVIM in three patients and blaCTX-M-15 plus porin defects in the remaining five patients. Inter-hospital spread of two major clones, ST512 and ST258, was found. Overall, 36.1% and 20.4% of strains were also resistant to colistin and tigecycline, respectively. Infection was diagnosed in 91 patients who received appropriate antibiotic treatment, combination therapy and removal of the infectious source in 73.6%, 59.3% and 28.5% of cases, respectively. Overall, 23 different antibiotic regimens were prescribed. In-hospital mortality was 25.8%. Multivariate analysis adjusted for appropriate treatment, combination therapy and infectious-source removal, showed that Charlson comorbidity score, intensive-care unit onset of infection, bacteraemia and infection due to a colistin-resistant CR-KP strain were independent risk factors for mortality. The spread of clones producing K. pneumoniae carbapenemases, mainly ST258, is currently the major cause of CR-KP infection in central Italy. We observed a high rate of resistance to colistin that is independently associated with worse outcome.

Activity of moxifloxacin in combination with vancomycin or teicoplanin against Staphylococcus aureus isolated from device-associated infections unresponsive to glycopeptide therapy.

We tested the in vitro bactericidal activity of moxifloxacin, a new 8-methoxyquinolone, alone and in combination with vancomycin or teicoplanin at different multiples of minimum inhibitory concentration (MIC) against 8 methicillin-ciprofloxacin-resistant Staphylococcus aureus (M-C-RSA) and 1 methicillin-ciprofloxacin susceptible S. aureus (M-C-SSA) recently isolated from device-associated infections unresponsive to or relapsing after glycopeptide therapy, despite device removal. MICs of vancomycin ranged from 1 to 4 microg/ml, MICs of teicoplanin ranged from 2 to 8 microg/ml; MICs of moxifloxacin were always 2 microg/ml against M-C-RSA isolates and 0.125 microg/ml against the M-C-SSA isolate. The 9 strains resulted tolerant when tested for vancomycin, teicoplanin, and moxifloxacin used alone at 2 x MIC. In all cases the combination of moxifloxacin and teicoplanin or vancomycin appeared to be bactericidal already at MIC concentration for glycopeptides plus 0.5 x MIC concentration for moxifloxacin. If these results are confirmed in vivo in animal experiments, the combination of moxifloxacin with glycopeptides might be useful for treating device-associated infections, and in preventing the frightening phenomenon of increasing MICs for glycopeptides.

Conservative medical therapy of infections following osteosynthesis: a retrospective analysis of a six-year experience.

The conventional therapeutic approach to bone infection associated with osteosynthesis is based on the idea that microbial eradication is most readily achieved by removal of the foreign material together with adequate antimicrobial therapy. This strategy usually requires implantation of external fixation devices with additional discomfort to the patient. We report our experience with conservative medical and antimicrobial therapy without removal of the osteosynthesis until adequate bone callus deposition is documented by bone radiography scan. Twenty patients with infections associated with intramedullary nailing (9 patients), screws and plate (9 patients) or screws (2 patients) were treated between 1995 to 2000. Osteosynthesis implantation sites were tibia (7 patients), femur (6 patients), femur and tibia (1 patient), humerus (1 patient), others (5 patients). Diagnosis of infection was based on clinical-microbiological evidence and confirmed by 99Tc-labeled leukocyte scan studies. Offending pathogens were Staphylococcus aureus 17 cases, Staphylococcus aureus + Escherichia coli, Staphylococcus epidermidis, unknown, 1 case each. Most infections were initially treated with intravenous or intramuscular teicoplanin +/- ciprofloxacin or rifampin followed by oral antimicrobial therapy usually with ciprofloxacin or minocycline plus rifampin. Mean duration of antimicrobial therapy was 27.7 weeks (range 12-64 weeks). All patients (100%) were cured, and none complained of side-effects requiring antibiotic therapy discontinuation. We conclude that conservative medical therapy is feasible for osteosynthesis-associated bone infection.

Prosthetic biologic valve endocarditis caused by a vancomycin-resistant (vanA) Enterococcus faecalis: case report.

We recently observed (February 1999) a 68-year old patient with endocarditis on a prosthetic biologic valve caused by a vancomycin-resistant Enterococcus faecalis. Broth dilution tests showed susceptibility to ampicillin (MIC=0.5 microg/ml), no high resistance to aminoglycosides (MIC for gentamicin <500 microg/ml) and resistance to vancomycin (MIC >256 microg/ml) and teicoplanin (MIC >16 microg/ml). A PCR assay detected vanA gene in this strain. A transthoracic echocardiogram did not show valvular vegetations. A possible endocarditis was diagnosed and the patient received ampicillin for 8 weeks and gentamicin for 6 weeks. The patient remained afebrile after a 4-month follow-up when he underwent surgical replacement of the dysfunctional bioprosthetic valve. Mitral valve was sterile on culture, but histology confirmed the diagnosis of previous endocarditis. This is the third case of endocarditis caused by vancomycin-resistant E. faecalis reported to date.

Antibiotic susceptibility and serotype distribution of Streptococcus pneumoniae causing meningitis in Italy, 1997-1999.

Because few data are available in Italy regarding antimicrobial susceptibility and serotype distribution of invasive Streptococcus pneumoniae strains, meningeal isolates collected at Italian hospitals during the years 1997-1999 were studied. The 12 most common serogroups, representing > 85% of the isolates, were 14, 23, 6, 4, 3, 9, 19, 8, 1, 12, 18, and 7 (in order of frequency). The serogroups identified in children < 5 years old were more limited in number: 80% are included in the 7-valent conjugate vaccines. Penicillin resistance was observed in 14 (9.5%) of 148 strains and increased from 5% in the first part of the study to 13% in the last part. Only 2 strains were fully penicillin resistant, and these belonged to serotype 9V. Thirty percent of the strains, mostly belonging to serogroups 14 or 6 and carrying either the ermB or the mef genes, were resistant to erythromycin.

Antimicrobial susceptibility of invasive Streptococcus pneumoniae in Italy by agar dilution method and E test.

Few data on antimicrobial susceptibility of invasive Streptococcus pneumoniae isolated in Italy are available. Ninety-two invasive isolates from all over the country collected from January 1997 to April 1998 were tested for sensitivity to penicillin, erythromycin, ceftriaxone, chloramphenicol, tetracycline, and trimethoprim/sulfamethoxazole by the agar dilution method. Five (5.4%) strains were resistant to penicillin (one highly, four intermediately resistant), 8 (8.7%) to chloramphenicol, 27 (29.3%) to erythromycin, 17 (18.5%) to tetracycline (16 highly, one intermediately), and 21 (22.8%) to trimethoprim/sulfamethoxazole (14 highly, 7 intermediately). All strains were susceptible to ceftriaxone, although the penicillin-resistant strain had the highest minimal inhibitory concentration. (MIC) value (0.5 microg/ml); three penicillin-resistant strains were also resistant to erythromycin. Eight strains were multi-drug resistant, being also resistant to at least three antibiotics. The commercially available E test was compared with the standard agar dilution method for the determination of MIC of penicillin, erythromycin, ceftriaxone, chloramphenicol, and trimethoprim/sulfamethoxazole. E test established the same susceptibility categories for 100% of the strains tested for penicillin and ceftriaxone, 99% for chloramphenicol, 97% for erythromycin, and 74% for trimethoprim/sulfamethoxazole. According to our results, E test was simple to perform, easy to interpret, and a valid method for susceptibility testing of S. pneumoniae. Our study shows that in Italy the rate of penicillin resistance in invasive isolates of S. pneumoniae is one of the lowest in Europe (5.4%), while the rate of erythromycin is very high (29.3%) and is reaching the highest rates of other Southern European countries.

Comparative in-vitro activity of moxifloxacin, penicillin, ceftriaxone and ciprofloxacin against pneumococci isolated from meningitis.

Minimum inhibitory concentrations of penicillin, ceftriaxone, ciprofloxacin, and moxifloxacin (BAY 12-8039), a new 8-methoxyquinolone, were determined for 60 cerebrospinal fluid isolates of Streptococcus pneumoniae collected during January 1997-April 1998 at Italian medical centres. Three reference isolates with predetermined MIC values (two penicillin- and multidrug-resistant isolates, one uniformly susceptible to all antibiotics) were also tested with the same antibiotics. The MIC90 of penicillin was < or = 0.03 mg/L (range < or = 0.03-2 mg/L), of ceftriaxone 0.06 mg/L (range < or = 0.03-0.5 mg/L), of ciprofloxacin 2 mg/L (range 0.5-8 mg/L) and of moxifloxacin 0.06 mg/L (range 0.03-0.12 mg/L). Moxifloxacin was effective against all the penicillin-resistant isolates tested, with an MIC of 0.06 mg/L. Moxifloxacin was 32-fold more active than ciprofloxacin and was not affected by penicillin and cephalosporin resistance. These results indicate that moxifloxacin could be useful for the treatment of both penicillin-sensitive and -resistant S. pneumoniae meningitis.

[Streptococcus bovis endocarditis. Clinical and microbiological observations and review of the literature]. / Endocardite da Streptococcus bovis. Analisi clinico-microbiologica retrospettiva e rassegna della letteratura.

Fourteen patients (11 men and 3 women) with Streptococcus bovis infective endocarditis have been observed by the Infectious Disease Section of our Department of Clinical Medicine between the years 1988-1998. The mean age was 63.2 years (range 35-85 years); 5 patients previously suffered valvular disease or had a valvular prosthesis, the infection involved the mitral valve in 6 patients, the aortic in 8, the prosthetic valve in 1. No patient developed cardiac failure or died during hospitalization; only 1 episode of major embolism (spleen) was observed. No patient required cardiac surgery. All patients became afebrile after starting antibiotic treatment; no cases of Streptococcus bovis relapse have been observed, during a six-month follow-up after antibiotics discontinuation, in 13 patients fully evaluated. The remaining patient was lost to follow-up. An underlying asymptomatic colonic neoplasm was diagnosed at colonoscopy in 7 of 11 evaluated patients. This study confirms that Streptococcus bovis infective endocarditis is relatively benign, but it stresses the frequency and potential severity of the associated colonic lesions, requiring colonoscopy and making the treatment of high risk lesion mandatory.

Fatal suppurative mesenteric thrombophlebitis caused by an Enterococcus faecalis highly resistant to aminoglycosides: case report.

A 56-year old man with non-Hodgkin's lymphoma and biliary tract endoprosthesis, developed chronic bacteremia caused by Enterococcus faecalis with high-level resistance to gentamicin and streptomycin. The sources of bacteremia were a device-associated biliary tract infection, a suppurative thrombophlebitis of the confluence of the superior mesenteric vein with the splenic vein as well as multiple liver and pancreatic abscesses. Despite antibiotic therapy and multiple drainages of abscesses, the patient died due to overwhelming infection.

Susceptibility and genetic relatedness of invasive Haemophilus influenzae type b in Italy.

Haemophilus influenzae type b (Hib) still causes a large portion of meningitis in children less than 5 year old in Italy because vaccination against this agent has not been fully implemented in the country. We have studied 78 Hib strains and 4 nontypable H. influenzae (NTHi) isolated from the cerebrospinal fluid of subjects with meningitis for susceptibility to ampicillin, chloramphenicol, and ceftriaxone. The macrorestriction profiles of chromosomal DNA obtained by pulsed-field gel electrophoresis (PFGE) following digestion with SmaI and ApaI were also determined. All strains except one were equally susceptible to the antibiotics tested. One Hib strain, the only beta-lactamase producer, showed an intermediate susceptibility to ampicillin (MIC = 2 microg/ml), while maintaining full susceptibility to chloramphenicol and ceftriaxone. The analysis of the PFGE patterns showed that most of the Hib isolates, including the beta-lactamase-positive Hib strain, belonged to the same clone or to closely related subclones. For three PCR-confirmed NTHi isolates, we obtained completely different PFGE profiles. In conclusion, resistance to ampicillin still appears to be a rare finding in Hib strains causing meningitis in Italy; moreover, PFGE showed that the population structure of invasive Hib is essentially clonal.

Teicoplanin in the treatment of enterococcal endocarditis: clinical and microbiological study.

Seven cases of enterococcal endocarditis treated with teicoplanin (7-10 mg/kg/day for 28-105 days) alone (one case) or in combination with aminoglycosides (six cases) were reviewed. All patients were cured. Serum bactericidal activity titres after intravenous gentamicin (5 mg/kg every 24 h) and teicoplanin (10 mg/kg every 24 h) were measured on day 7 of treatment in four patients against five enterococcal isolates: mean titres were 1:54 (range 1:16-64) and 1:22 (1:8-32) at 0.5 and 24 h post-infusion, respectively. Time-kill studies showed synergy between teicoplanin and gentamicin against three isolates. We conclude that single daily-dose teicoplanin/gentamicin combined therapy may represent a rational alternative to standard penicillin/gentamicin therapy and a useful regimen for home treatment of selected cases of enterococcal endocarditis.

Activity of quinupristin/dalfopristin against Streptococcus pneumoniae in vitro and in vivo in the rabbit model of experimental meningitis.

We tested the efficacy of quinupristin/dalfopristin, an antibiotic made up of dalfopristin (70%) and quinupristin (30%) against a large panel of Streptococcus pneumoniae strains. The pneumococcal isolates (217) included 200 penicillin-resistant and 17 penicillin-susceptible clinical isolates. Eighty-nine of the 200 resistant bacteria showed an intermediate level and 111/200 showed a high level of resistance to penicillin. Of the highly resistant strains, 56/111 belonged to the multidrug-resistant Spanish/USA epidemic clone of S. pneumoniae, as defined by appropriate genetic techniques. The resistant panel also included six isolates of another multidrug-resistant epidemic clone: isolates with capsular type 6B belonging to the Spanish/Icelandic clone of S. pneumoniae. Quinupristin/dalfopristin had a uniform mean MIC of 0.25 mg/L against all pneumococcal isolates, including 37 strains representing a wide spectrum of erythromycin MICs, from 0.03 up to 8.0 mg/L. Quinupristin/dalfopristin showed powerful bactericidal activity against a penicillin-susceptible test strain in vitro and against representatives of both the Spanish/USA and the Spanish/Icelandic multidrug-resistant clones. The rate of bactericidal activity was independent of drug concentration between 2.5 x and 10 x MIC. Quinupristin/dalfopristin was also tested in a rabbit model of experimental meningitis using 50 mg/kg i.v. bolus injections and a penicillin-susceptible capsular type 3 S. pneumoniae strain as the test organism. Quinupristin/dalfopristin had no effect on the intracisternal growth of bacteria when the drug was injected before CSF inflammation, whereas it caused a 2 log kill in 2 h, after which bacterial growth in the CSF resumed, when injected i.v. at a time of inflammation. When a second dose was given 2 h later, this produced a 3 log loss of viability after 4 h. A single injection of ampicillin 50 mg/kg i.v. caused a similar 3 log kill after 4 h under comparable conditions.

Spread of the serotype 23F multidrug-resistant Streptococcus pneumoniae clone to South Korea.

Thirty-eight antibiotic-resistant isolates of Streptococcus pneumoniae recovered in a hospital in Seoul, Korea, between February 1990 and March 1992 were analyzed for serotype, antibiotic susceptibility patterns, and chromosomal relatedness using pulsed-field gel electrophoretic (PFGE) analysis of SmaI chromosomal digests. Most of the isolates were from sputum samples, and a few strains were from otitis media and meningitis. The great majority of isolates (34 of 38, or 89%) were multiresistant, sharing virtually identical, elevated minimal inhibitory concentration (MIC) values (microgram/ml) for penicillin (1-2), chloramphenicol (12-25), tetracycline (25-30), and sulfamethoxazole/trimethoprim (> 100). Twenty of the isolates were also resistant to erythromycin, and all isolates were also considered to be resistant to ceftriaxone and cefotaxime (1-2) according to the new breakpoint definitions. The most frequent serotypes were 23F (17 of 38) and 19F(14 of 38); 2 belonged to serotype 15B and 1 of 24F. Of the remaining 4 isolates (2 serotype 3, 1 type 6B, and 1 type 9V) all were resistant to tetracycline and sulfamethoxazole/trimethoprim and with the exception of 1 of the type 3 strains, were also resistant to chloramphenicol. Eleven of the 14 serotype 19F isolates shared a relatively homogeneous PFGE pattern, which was indistinguishable from the PFGE pattern shown by most (12 of 17) of the 23F isolates. The PFGE pattern of these 19F and 23F isolates was also indistinguishable from the PFGE pattern shown by representative multiresistant capsular type 23F isolates from Croatia, Portugal, and New York City and the findings document the extensive geographic spread of this multidrug-resistant S. pneumoniae clone. The data also suggests in vivo capsular transformation of the multiresistant clone from serotype 23F to serotype 19F.

Penicillin-resistant and multidrug-resistant Streptococcus pneumoniae in a pediatric hospital in Zagreb, Croatia.

Sixty-four penicillin-resistant Streptococcus pneumoniae isolates [benzylpenicillin minimal inhibitory concentrations (MICs) between 0.05 and 1.6 micrograms/ml] recovered at the Pediatric Hospital "Dr. Fran Mihaljevic" in Zagreb, Croatia between October 1990 and March 1993 were analyzed for serotype, antibiotic susceptibility patterns, and chromosomal relatedness using pulsed-field gel electrophoretic (PFGE) analysis of chromosomal DNA fragmented by digestion with the SmaI endonuclease. Hospital "Dr. Fran Mihaljevic" services the capital of Croatia and its vicinity. Most of the isolates were from nasopharyngeal carriage, but several isolates were from otitis media, sinusitis, and meningitis. Most isolates belonged to either serotype 23F (36/64) or 19F (12/64); the rest, including three 15C isolates, were in 11 additional distinct serotypes. The overwhelming majority (25/36) of the serotype 23F isolates had penicillin MIC values of 1-2 micrograms/ml and shared variants of a common PFGE pattern, closely related to the PFGE identified in multiresistant pneumococci of the same serotype with wide geographic spread to Spain, Portugal, France, and the United States. This group of bacteria was also resistant to tetracycline, chloramphenicol, and sulfamethoxazole/trimethoprim. In contrast to the relative genetic and phenotypic homogeneity of the more highly penicillin resistant isolates, pneumococci with penicillin MICs between 0.5 and 0.4 microgram/ml (29/64) were distributed in 13 different serotypes and as many as 20 distinct PFGE patterns.

Potential of clindamycin in addition to vancomycin for the treatment of oxacillin-resistant Staphylococcus aureus septicemia persisting under vancomycin therapy.

We observed seven patients with persistent fever and staphylococcemia under vancomycin-containing antimicrobial regimens who promptly improved as clindamycin was added to the initial antibiotics. Moreover, in all these patients a striking increase in peak and trough serum inhibitory activity (SIR) and serum bactericidal activity (SBA) levels was observed after addition of clindamycin. SIA and SBA levels after administration of a single dose of vancomycin (500 mg), clindamycin (600 mg) or vancomycin + clindamycin were also measured in three healthy volunteers against six ORSA isolates. Unsatisfactory peak SBA levels (0% of cases 1:8) were obtained after vancomycin administration. Vice versa, peak SBA levels 1:8 were obtained in 94% of the cases after clindamycin and in 100% of cases after vancomycin + clindamycin. Time-kill studies showed a borderline or incomplete bactericidal activity of vancomycin against three ORSA isolates from infections that manifested poor or slow response to vancomycin therapy. The combination with clindamycin did not result in a synergistic interaction between the two drugs. It is concluded that addition of clindamycin may be useful in some cases of ORSA septicemia that show poor or slow response to vancomycin therapy. The recommendation for a wider use of this combination of antibiotics requires further documentation of efficacy.

[The multiresistance of Streptococcus pneumoniae: a global danger]. / La multiresistenza dello streptococco polmonare: un pericolo mondiale.

S. pneumoniae causes several serious and potentially life-threatening community-acquired diseases, and there are 5 million deaths per year globally. In multidrug-resistant clones (those with resistance to erythromycin, tetracycline, chloramphenicol, penicillin, and trimethoprim-sulfamethoxazole), treatment of even relatively localized pneumococcal infection may require hospitalization because of the need to use parenteral vancomycin. Thanks to the tremendous increase in the size of populations at high risk, and to the increased mobility of human populations the problem has been amplified to one of global dimensions: during the last decade multidrug-resistant clones have been clinically isolated in Spain, South Africa, Hungary, USA, Croatia, and South Korea. In Italy, epidemiologic data are unknown. Pneumococci would have developed resistance modifying the PBP genes, probably acquiring foreign DNA from taxonomic related streptococci and became global pathogens because of geographic spread of multidrug-resistant clones during the 1990s. These theses have been demonstrated using a relatively new technique of molecular epidemiology: Pulsed-Field Gel Electrophoresis, able to recognize chromosomal similarity among clinical isolates. About 50% of the pharmaceutical company had either reduced or phased out their natibacterial programs five years ago. There are relatively few new drugs ready for introduction today, and promising agents are still in the development stage and will require more years of testing for clinical efficacy.

Infections by ampicillin-resistant enterococci: a case-control study.

We identified 17 (20%) of 83 consecutive enterococcal isolates from hospitalized patients with documented infection as high-level ampicillin-resistant enterococci (ARE). Of these, 16 isolates were identified as Enterococcus faecium and 1 isolate as Enterococcus raffinosus. A case-control study found no significant differences with respect to underlying diseases, central venous catheterization, nosocomial acquisition of the infection and sites of infection. Patients with ARE infection were older and had a higher inhospital fatality rate than those with ampicillin-susceptible Enterococcus (ASE) infection. Hospitalization in a surgery service (usually for an abdominal procedure), prolonged hospital stay, prior treatment with antibiotics (in particular imipenem and metronidazole), were also more frequent among patients with ARE infection. ARE isolates were more frequently resistant to imipenem, ciprofloxacin and streptomycin than ASE isolates.