Dental unit water content and antibiotic resistance of Pseudomonas aeruginosa and Pseudomonas species: a case study

Background

Many studies consider the contamination of dental unit waterlines (DUWLs), but few of them have studied the possible presence of antibiotic resistant Pseudomonas aeruginosa in the DUWLs.

Aims

Investigation of the presence of P. aeruginosa and Pseudomonas spp. strains in DUWLs and evaluation of their resistance to six antibiotics (ceftazidime, netilmicin, piperacillin/tazobactam, meropenem, levofloxacin, colistin sulfate) at a public dental clinic in Milan, Italy.

Results

Dental units were contaminated by P. aeruginosa with loads of 2–1,000 CFU/L and were mainly located on the mezzanine floor, with a range of 46–54%, while Pseudomonas spp. were primarily found on the first and second floors, ranging from 50 to 91%. P. aeruginosa was antibiotic resistant in 30% of the strains tested, andPseudomonas spp. in 31.8% . Cold water from controls was also contaminated by these microorganisms.

Conclusion

Monitoring antibiotic resistance in the water and adopting disinfection procedures on DUs are suggested within the Water Safety Plan.

Can Pseudomonas aeruginosa growth be modulated by natural compounds?

Pseudomonas aeruginosa is an opportunistic human pathogen that frequently induces antibiotic resistance, as it mainly tends to form biofilms. Iron chelation may be an intriguing strategy to contrast bacterial growth. Lactoferrin is a natural compound able to chelate iron. A new multi-component medical device also contains lactoferrin. This study analyzed this compound investigating the in vitro capacity to inhibit Pseudomonas aeruginosa growth. In conclusion, this study demonstrated that a multicomponent medical device (Saflovir), also containing lactoferrin, could inhibit the in vitro growth of P. aeruginosa. This activity could be positively used in the prevention of respiratory nasal infections.

A new urinary catheter design reduces in-vitro biofilm formation by influencing hydrodynamics

AIM

To evaluate the performance of a new catheter design based on different hydrodynamics aiming to reduce the development of biofilm, and compare it with a conventional Foley catheter (FC).

METHODS

The new proposed design (NPD) catheter is a modification of the FC, based on asymmetric positioning of the balloon and additional drainage holes allowing continuous urine drainage and complete voiding of the bladder. A first experiment was undertaken to assess drainage capability, and a second experiment was performed using a bioreactor with a set-up simulating the bladder and using the test catheter as a flow-through system. The biofilm formation of five bacterial species associated with catheter-associated urinary tract infection (CAUTI) was determined after 24 h of incubation using an MTT assay. Morphological evaluation was performed using scanning electron microscopy. In-vitro determination of residual fluid, and quantitative and morphological data on biofilm formation on the intravesical and intraluminal parts of the tested catheters were assessed.

RESULTS

Residual fluid was significantly higher in the FC (5.60 ± 0.43 mL) compared with the NPD catheter (0.2 ± 0.03 mL). The NPD catheter showed significantly less biofilm formation (P<0.0001) than the FC. Catheter design had a variable effect on biofilm formation depending on the bacterial strain tested. There was significantly less intraluminal biomass compared with intravesical biomass in both catheters (P<0.0001). Multi-layered biofilms that covered the FC surfaces completely were seen for all tested strains, while the NPD catheter surfaces showed reduced biofilm formation.

CONCLUSIONS

Modifications of the hydrodynamic characteristics of a catheter can significantly reduce bacterial colonization. Integrated design approaches combining chemical, mechanical and topographical elements can help to reduce the occurrence of CAUTI.

Fusidic acid betamethasone lipid cream

Bacterial infections of the skin and soft tissues are frequent disorders. They can be primitive infections (e.g. impetigo, folliculitis) or secondary infections complicating other diseases, particularly atopic dermatitis. The most common aetiologic agent is Staphylococcus aureus. Topical antibiotic therapy may be sufficient in many instances to control these infections. Fusidic acid is an antibiotic used topically on the skin which is very active against S. aureus, including methicillin-resistant strains, and other Gram-positive bacteria. Resistance rates to fusidic acid are stably low. A fusidic acid and betamethasone formulation in a lipid-enriched cream (lipid cream) has been recently developed in order to provide effective antibacterial and anti-inflammatory activities in conjunction with a powerful emollient and moisturising effect. This preparation may be especially useful in patients with atopic-infected eczema.

Prolonging culture to 15 days improves bacterial detection in bone and joint infections

Since the optimal incubation period of cultures for diagnosis of bone and joint infections is still a matter of debate, the present study aimed to evaluate the effects of different incubation periods (5 and 15 days) on microbial isolation. Samples from 387 patients with bone and joint infections (including prosthetic ones) were analyzed from March 2012 to February 2014. In 197 patients (51 %) growth was obtained within 48 hrs, while in 124 (32 %) and 66 (17 %) patients cultures yielded positive results within and after 5 days of incubation, respectively. Of 449 microorganisms isolated, 247 grew within 48 hrs, 131 within the first 5 days of incubation while 71 were isolated after 5 days. Staphylococcus aureus was the most frequently isolated pathogen within 48 hrs, while Propionibacteria were prevalently isolated after 5 days of incubation. Interestingly, about 25 % of microorganisms isolated after 5 days of incubation were coagulase-negative staphylococci. Extending incubation period of broth cultures improves isolation rates of pathogens involved in bone and joint infections thus improving management of these infections.

Iron status evaluation as a marker of postoperative joint infection: a pilot study

We evaluated the effect of different inflammatory conditions on iron status and, as a consequence, the possible use of iron markers as indicators of infection in the diagnosis of postoperative prosthetic orthopaedic joint infections. The study population was consisted of 26 patients undergoing revision of total hip or total knee joint arthroplasty and subdivided into three groups according to the cause of prosthesis implant failure: 10 as having had previous infection (Group A), 10 patients were categorized as having infection (Group B); and the remaining 6 (Group C) as not having infection. These patients were assayed for mean corpuscular haemoglobin concentration (MCHC) and serum values of iron (Fe), ferritin (Fer), transferrin (Tf), soluble transferrin receptor (sTfR), and transferrin saturation (sat Tf). Septic patients display statistically significant lower serum iron concentration, higher sTfR and ferritin levels, lower, but not statistically significant, MCHC compared to non septic ones. Little differences were observed for Tf, sat Tf, tibc, TfR index, among the three groups of patients. Our study suggests that iron status parameters, in particular serum iron, ferritin, sTfR and TfR index, could be useful tools for the early detection and the diagnosis of orthopaedic prosthetic joint infections.

Modulation of biofilm of strains isolated from patients with chronic obstructive pulmonary disease by levofloxacin, moxifloxacin, ciprofloxacin, amoxicillin/clavulanic acid and ceftriaxone

The ability of levofloxacin, moxifloxacin, ciprofloxacin, amoxicillin/clavulanic acid and ceftriaxone to interfere on biofilm produced by Pseudomonas aeruginosa, Haemophilus influenzae and Streptococcus pneumoniae isolated from patients with chronic obstructive pulmonary disease was evaluated. The effects of antibiotics were evaluated on formation of biofilm (at 1/2, 1/4 and 1/8 X MIC) and on preformed biofilm (at epithelial lining fluid peak concentrations) by means of a spectrophotometric method. Levofloxacin was the most active compound followed by ciprofloxacin, moxifloxacin and amoxicillin/clavulanic acid and ceftriaxone. Levofloxacin may contribute to clear the reservoir of pathogens involved in chronic obstructive pulmonary disease, thus leading to decreased occurrence of acute exacerbations.

Procalcitonin, C-reactive protein, interleukin-6, and soluble intercellular adhesion molecule-1 as markers of postoperative orthopaedic joint prosthesis infections

There is a universally recognized need to identify new, reliable markers of inflammation that can aid in the rapid diagnosis of orthopaedic joint prosthesis infections (OJP-Is). Since prompt diagnosis is key to timely intervention in the course of infection, different molecules have been studied. In this study, we examined three groups of patients: those with prosthesis infection, those without infection, and a third group with previous infection in whom the infection had been cleared. Four presumed markers of infection were tested: procalcitonin (PCT); C-reactive protein (CRP); interleukin-6 (IL-6); and soluble intercellular adhesion molecule-1 (sICAM-1). The results showed that PCT cannot be considered as a good marker of periprosthetic infection as no statistically significant difference in serum PCT levels emerged between patients with infection and controls or patients without infection. In contrast, both sICAM-1 and CRP may be considered as good markers of infection, as measurement of their levels allowed us to distinguish between patients with and without infection, and between patients with infection and those with previous infection, since marker levels quickly returned to baseline values after clearance of the infection. IL-6 was found to be a good marker for inflammation, as it distinguished between patients with infection and the other groups. In the patients with previous infection, the IL-6 values remained high versus the controls but lower and with a statistically significant difference versus the patients with infection. Further studies are needed to determine the cut-off value of IL-6 between patients with infection and those with previous infection.

Antibacterial activity of cefditoren against major community-acquired respiratory pathogens recently isolated in Italy

In this study we evaluated the in vitro activities of cefditoren--a broad-spectrum oral cephalosporin--and other comparator agents against 2,396 fresh isolates from community-acquired respiratory tract infections, collected from 6 clinical Italian microbiology laboratories. On penicillin-susceptible pneumococci and Streptococcus pyogenes, cefditoren demonstrated to be the most active antibiotic (MIC(90)values of 0.03 and 0.06 mg/L respectively), showing only a slight decrease in potency on penicillin-intermediate and resistant pneumococci (MIC(90)value 0.5 mg/L, 1.0 mg/L respectively). All the other comparators displayed MIC(90 )values of 4 - 8 mg/L for penicillins and of 4 to >64 mg/L for the oral cephalosporins. Cefditoren and levofloxacin were the most active against MSSA (MIC(90)0.5 mg/mL). Cefditoren displayed a uniformly potent inhibitory activity (MIC(90)of 0.03 mg/L) against all strains of Haemophilus influenzae, regardless of their ampicillin resistance (mediated or not by beta-lactamase production), while against Moraxella catarrhalis MIC(90)values were higher against beta-lactamase-positive (0.25 mg/L). Cefditoren was active also against Klebsiella pneumoniae and Escherichia coli : in this case its activity was comparable with that of levofloxacin. In conclusion, cefditoren, due to its potent activity, is a new effective therapeutic option for the treatment of respiratory tract infections.

Prevalence of the internalization-associated gene prtF1 in a bacterial population of Streptococcus pyogenes isolated from children with acute pharyngotonsillitis before and after antibiotic therapy

The prevalence of the internalization-associated prtF1 gene was studied in 837 isolates of Streptococcus pyogenes obtained from 713 pediatric patients presenting with acute pharyngotonsillitis before and after antibiotic therapy. Its association with macrolide resistance and with bacteriological treatment failure was determined. The bacterial population isolated from baseline pharyngeal swabs showed an overall prtF1 positivity rate of 33%. A higher prtF1 positivity was found among erythromycin-resistant strains (45%) showing, however, marked differences between the inducible (iMLS), constitutive (cMLS), and efflux pump (M) resistance phenotypes. The prevalence was statistically higher (p < 0.001) in strains belonging to iMLS (84%) and cMLS (67%) phenotypes as compared to the M phenotype (15%). Interestingly, the prevalence of the prtF1 gene was significantly lower (p = 0.04) in strains belonging to M resistance phenotype as compared to erythromycin-susceptible strains (28%). Failed bacterial eradication was demonstrated in 124 patients. The prtF1 positivity rate remained unchanged in strains isolated before and after therapy in patients treated with macrolides (9/54). On the other hand, the positivity rate for the prtF1 gene was significantly higher (p = 0.015) in strains isolated after therapy with beta-lactams (21/70) as compared to baseline isolates (6/70), indicating a differential selection imposed on the organism by these agents. Finally, a high overall eradication rate (88%) of prtF1-positive isolates, belonging to both the erythromycin-susceptible and -resistant phenotypes, was demonstrated following macrolide treatment.

Pharmacodynamics of levofloxacin and ciprofloxacin in a murine pneumonia model: peak concentration/MIC versus area under the curve/MIC ratios

During the last decade some studies have shown that the area under the curve (AUC)/MIC ratio is the pharmacodynamic index that best predicts the efficacies of quinolones, while other studies suggest that the predictive value of the peak concentration/MIC (peak/MIC) ratio is superior to the AUC/MIC ratio in explaining clinical and microbiological outcomes. In classical fractionated dose-response studies with animals, it is difficult to differentiate between the AUC/MIC ratio and the peak/MIC ratio because of colinearity. Three different levofloxacin and ciprofloxacin dosing regimens were studied in a neutropenic mouse pneumonia model. The different regimens were used with the aim of increasing the AUC/MIC ratio without changing the peak/MIC ratio and vice versa. The first regimen (RC) consisted of daily doses of 5 up to 160 mg/kg of body weight divided into one, two, or four doses. In the second regimen (R0), mice were given 1.25 mg/kg every hour from 1 to 23 h, while the dose given at 0 h was 2.5, 5, 10, 20, 40, or 80 mg/kg. In the third regimen (R11), mice also received 1.25 mg/kg every hour from 0 to 23 h; but in addition, they also received 2.5, 5, 10, 20, 40, or 80 mg/kg at 11 h. The level of protein binding was also evaluated. The results indicate that the unbound fraction (f(u)) was concentration dependent for both levofloxacin and ciprofloxacin and ranged from approximately 0.67 to 0.88 for both drugs between concentrations of 0.5 and 80 mg/liter. The relationships between the AUC/MIC ratio and the number of CFU were slightly better than those between the peak/MIC ratio and the number of CFU. There was no clear relationship between the amount of time that the concentration remained above the MIC and effect (R(2) < 0.1). For both drugs, the peak/MIC ratio that resulted in a 50% effective concentration was lower for the R0 and R11 dosing regimens, indicating the importance of the AUC/MIC ratio. The same was true for the static doses. Survival studies showed that for mice treated with the low doses the rate of survival was comparable to that for the controls, but with the higher doses the rate of survival was better for mice receiving the R0 regimen. We conclude that for quinolones the AUC/MIC ratio best correlates with efficacy against pneumococci and that the effect of the peak/MIC ratio found in some studies could be partly explained by concentration-dependent protein binding.

Bacteriological and clinical efficacy of various antibiotics used in the treatment of streptococcal pharyngitis in Italy. An epidemiological study

A total of 123 community paediatricians and 23 microbiology laboratories studied the clinical and bacteriological efficacy of treatment of group A streptococcal pharyngitis in Italy. Of 1065 patients, from whom Streptococcus pyogenes was isolated, 723 returned to follow up and of these 138 (19%) still had a positive throat culture. The erythromycin resistance (ER) rate was 23.7% with resistance phenotype distribution of: 31.7% constitutive (CR), 26.6% inducible (IR) and 41.7% efflux pump (M) resistance phenotype. All strains were susceptible to the beta-lactam agents tested. CR strains were highly resistant to all 14, 15 and 16 membered macrolides with the exception of rokitamycin which showed activity against 37.8% of isolates. All phenotype M and some IR isolates were susceptible to clindamycin, rokitamycin, josamycin and spiramycin; clarithromycin was active against a small percentage of strains belonging to the IR and M phenotype. Bacterial eradication was found in 85.5, 78.7 and 75.8% of the penicillin, macrolide and cephalosporin treated groups. Genotyping of strains showed that 8.7% of the 19% of cases classified as 'failed bacterial eradication' were due to recolonization with a different isolate, observed exclusively among beta-lactams treated patients. Clinical cure was achieved in a high percentage of cases, irrespective of the antibiotic prescribed, with the best clinical efficacy being found following therapy with amoxycillin and clarithromycin (90.9%).

Distribution and antibiotic resistance of isolates from lower respiratory tract and blood cultures from patients in three Italian intensive care units: a 2-year comparison

The distribution and antibiotic resistance of major pathogens isolated from patients in ICUs were studied by three Italian microbiological laboratories. Consecutive aerobic strains were collected over two different time periods from protected brushing bronchoscopy, broncho-alveolar lavage and blood cultures. A total of 420 strains were isolated during the first period (47.3% gram-negative and 52.7% gram-positive) and 412 over the second period (50.5% gram-negative and 49.5% gram-positive). Pseudomonas aeruginosa was the most frequently isolated organism from the respiratory tract followed by Staphylococcus aureus. Methicillin resistance was 47.9 and 44.5% in S. aureus and 63.0 and 65.1% in coagulase-negative staphylococci over the two periods. No glycopeptide-resistance was found in gram-positive organisms. Ceftazidime-resistance in Klebsiella pneumoniae was very high.

Antibiotic susceptibility of group A streptococci in 2 Italian cities: Milano and Catania

Resistance to macrolides has increasingly been reported for Group A streptococci. In this study, the in vitro antibiotic susceptibility pattern of 305 clinical isolates of S. pyogenes was determined. Strains were isolated during 1996 from pharyngeal swabs of children with uncomplicated pharyngitis living in 2 Italian cities: Milano and Catania, situated in the North and South of Italy, respectively. All isolates were found to be fully susceptible to penicillin and other beta-lactam agents tested. Susceptibility to macrolides differed markedly between the two centers with relatively high resistance rates to erythromycin being observed in Milano (30%) as compared to Catania (3%). Resistance to erythromycin was always crossed with that of the other 14- and 15-membered macrolides tested. However, resistance to josamycin and clindamycin was generally found in approximately 25% of the erythromycin-resistant (ER) strains. The erythromycin-resistant isolates from Milano and Catania (58 strains) were further subdivided into the three previously described resistance phenotypes: constitutive, inducible, and novel resistance phenotypes. The novel resistance phenotype accounted for 58% of all resistant strains, while 17% and 26% were found to be of the inducible and constitutive resistance phenotypes. Strains of the novel resistance phenotype were characterized by lower MIC values (MIC90 = 16 mg/L) to 14 and 15 carbon atom macrolides as compared to the other two phenotypes (MIC90 > 128 mg/L), and retained susceptibility to clindamycin and to josamycin, a 16 carbon atom macrolide. Resistance to tetracyclines was found in 25% to 36% of the ER isolates as compared to 2% to 10% of the susceptible strains. In particular, resistance to this agent was more commonly associated to isolates belonging to the novel and constitutive resistance phenotypes. MIC values for chloramphenicol in all isolates were within the susceptible or intermediate range; decreased susceptibility to this agent did not appear to be associated with erythromycin resistance.

High incidence of erythromycin-resistant Streptococcus pyogenes in Monza (North Italy) in untreated children with symptoms of acute pharyngo-tonsillitis: an epidemiological and molecular study

A retrospective analysis of susceptibility data available for Group A streptococcal isolates collected between January 1990 and January 1996 at the Hospital Microbiology Laboratory of Monza (North Italy), showed a sharp rise in the erythromycin resistance rates during the last 3 years. Streptococcus pyogenes resistant to erythromycin accounted for approximately 1% of strains isolated between 1990 and 1992; the percentage then rose from 5% in 1993 to almost 39% in 1995. In January 1996, the resistance rates peaked to 81%. A prospective controlled study performed between March and May of 1996 to determine the percentage of erythromycin-resistant Group A streptococci isolated in Monza from untreated children with acute pharyngo-tonsillitis, gave further confirmation of a high rate of erythromycin resistance (47%) in this area. Molecular characterization by T-serotyping and pulse-field gel electrophoresis analysis of 25 erythromycin-resistant Group A streptococcal isolates, showed a relatively high degree of heterogeneity among these strains, demonstrating that the increased resistance is not caused by the spread of a single clone.

Sensitivity to sparfloxacin and other antibiotics, of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis strains isolated from adult patients with community-acquired lower respiratory tract infections: a European multicentre study. SPAR Study Group. Surveillance Programme of Antibiotic Resistance

A survey of resistance to sparfloxacin was carried out in ten European countries, namely Slovakia, France, Germany, Great Britain, Hungary, the Republic of Ireland, Italy, The Netherlands, Portugal and Spain. Respiratory samples were collected from 4297 patients with lower respiratory tract infections and cultured for the presence of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. Altogether 2101 strains were isolated and tested for their susceptibility to sparfloxacin, ciprofloxacin, erythromycin, tetracycline and penicillin G (S. pneumoniae) or amoxycillin (H. influenzae and M. catarrhalis). Each country tested strains using methods commonly used in that country, and with breakpoints selected based on those used in that country. Penicillin resistance in pneumococci was seen in those countries in which it had been reported previously, namely Spain, France and Hungary. Only four strains of pneumococci were resistant to sparfloxacin (MIC > or = 2 mg/L), while ciprofloxacin-resistant strains were isolated more frequently, particularly in the Republic of Ireland and Hungary. Almost all of the strains of H. influenzae tested were resistant to erythromycin, (MIC50 > or = 4 mg/L), but all strains were highly sensitive to sparfloxacin (MIC90 < or = 0.06 mg/L). The number of strains of H. influenzae producing beta-lactamase varied between countries, whereas most strains of M. catarrhalis produced beta-lactamase. In M. catarrhalis, erythromycin and tetracycline resistance was rare, but sensitivity to amoxycillin varied. Sparfloxacin was particularly active against H. influenzae and M. catarrhalis, and was the most active compound tested. Overall, the activity of sparfloxacin was greater than that of ciprofloxacin against all three pathogens, and resistance to it was rare.

Effects of pidotimod on macrophage functions in methylprednisolone-treated mice

CD-1 mice were treated with methylprednisolone (mPDN) 2-5 mg/kg s.c., for 11 or 6 days, in order to achieve an immunosuppressed state. For the same length of time a group of mice also received pidotimod ((R)-3-[(S)-(5-oxo-2-pyrrolidinyl) carbonyl]-thiazolidine-4-carboxylic acid. PGT/1A, CAS 121808-62-6) i.p. at 100 or 10 mg/kg. At the end of treatment, peritoneal macrophages (MO) were recovered, purified by adherence to plastic and activated in vitro with different stimuli. After 24 h of incubation, the supernatants were collected and assayed for the presence of tumor necrosis factor-alpha (TNF-alpha) and nitrite (NO2-), which is the stable derivative of nitric oxide (NO) in acqueous solution. It is well known that TNF-alpha and NO represent two out of many molecules secreted by activated MO which are essential for killing microorganisms and for natural response to infections. It was observed that MO from mPDN-treated mice were unable to produce sufficient levels of both TNF-alpha and NO when stimulated in vitro with lipopolysaccharide, IFN-gamma or conidia from an opportunistic fungus, Aspergillus fumigatus, confirming that corticosteroids are able to inhibit the antimicrobial activity of MO. However, MO from mice received mPDN plus pidotimod fully recovered the capacity to produce TNF-alpha and NO in response to the same stimuli. Optimal dose of pidotimod was 100 mg/kg. In addition, pidotimod was also able to reconstitute the cellularity of the peritoneum and of the spleens of mice immunodepressed by mPDN.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum levels of flurithromycin ethylsuccinate in healthy volunteers

The serum levels of flurithromycin ethylsuccinate achieved 30 min after a single oral dose of 375 mg were found to be equal or above the minimal inhibitory concentrations for sensitive strains, when administered to 12 healthy volunteers. The serum half-life was found to be approximately 4 h.

Rufloxacin once daily versus ofloxacin twice daily for treatment of complicated cystitis and upper urinary tract infections. Italian Multicentre UTI Rufloxacin Group

The efficacy and safety of rufloxacin once daily was compared with that of ofloxacin b.i.d. for therapy of complicated cystitis and upper urinary tract infections. Eighty-three patients were randomly assigned to receive rufloxacin as a loading dose of 400 mg on the first day, followed by 200 mg s.i.d., and 80 received ofloxacin 300 mg b.i.d. Both agents were administered orally for a median duration of eight days. Bacterial elimination rates after treatment were 90% for rufloxacin and 81% for ofloxacin. Half of the treatment failures occurred in patients with infections caused by uropathogens that became either less sensitive or resistant to the quinolones being studied. At a two-week follow-up, recurrences had not occurred in any of the rufloxacin patients and had occurred in 17% of the ofloxacin patients. Minor adverse reactions were reported by 12 and 13 patients, respectively. Rufloxacin once daily is as effective as ofloxacin b.i.d. for the treatment of complicated cystitis and upper urinary tract infections.

Steady-state pharmacokinetics of rufloxacin in elderly patients with lower respiratory tract infections

The pharmacokinetics of rufloxacin, after repeated doses, was evaluated in 12 elderly patients with lower respiratory tract infections. Patients were given a single loading dose of 400 mg on the first day of treatment and single daily maintenance doses of 200 mg for the next 6-9 days. Serum concentrations of the drug were determined by high-performance liquid chromatography (HPLC) at regular intervals during treatment and fitted to a one-compartment open model for repeated doses. The maximum serum concentration after the first dose was 6.46 +/- 1.06 (mean +/- SEM) micrograms/ml and was reached in 4.3 +/- 0.8 h after the first administration. The elimination half-life was 28.7 +/- 4.1 h. The area under the serum levels-time curve from 0 to 24 h was 103 +/- 14 micrograms/h/ml after the first dose. On the last day of observation it increased to 155 +/- 28 micrograms/h/ml, with a mean extent of accumulation of 2.3 +/- 0.3 times. The elimination half-life was comparable to those in other studies in healthy young subjects, while plasma levels were about 80% higher. These results suggest that in elderly patients elevated drug concentrations may be reached in the serum. Although no untoward reactions related either to the drug concentration in serum or the dose have been noted with rufloxacin, this patient population should nevertheless be monitored carefully for adverse effects.

Pharmacokinetics of rufloxacin in healthy volunteers after repeated oral doses

Rufloxacin is a new broad-spectrum fluoroquinolone antibacterial agent. The pharmacokinetics and safety of rufloxacin were evaluated after repeated oral administration to healthy volunteers. The drug was administered once a day for 6 consecutive days following two different dose schedules. The first group of 11 subjects was given a loading dose of 300 mg on the first day and 150 mg on the subsequent 5 days. The second group of 12 subjects was given a loading dose of 400 mg and 200 mg for 5 days. Serum levels and urine concentrations of rufloxacin were determined by microbiological assay. A simultaneous fit of all data points for each subject was done according to a one-compartment open model. The drug was rapidly absorbed (absorption half-life 17 +/- 6 min in the 300 + 150 mg and 11 +/- 5 min in the 400 + 200 mg dose regimen group) and reached maximal serum concentrations (2.77 +/- 0.24 and 3.62 +/- 0.35 micrograms/ml) 4.2 +/- 0.4 and 4.0 +/- 0.9 h after the first administration. Steady-state serum concentrations (3.19 +/- 0.31 and 4.06 +/- 0.33 micrograms/ml) were reached in 3.7 +/- 0.7 and 4.5 +/- 0.4 days. Elimination half-lives were 29.5 +/- 2.4 and 36.0 +/- 2.8 h. Apparent volumes of distribution were 111 +/- 8 and 136 +/- 16 liters and apparent plasma clearances were 46 +/- 5 and 44 +/- 4 ml/min. Renal clearances were 18 +/- 3 and 17 +/- 2 ml/min.(ABSTRACT TRUNCATED AT 250 WORDS)

In-vitro activity of cefpodoxime proxetil (RU 51807): a comparative disk diffusion study on isolates from geriatric patients

997 strains isolated from clinical specimens arrived at the "Pio Albergo Trivulzio" microbiology laboratory were tested using disks of cefpodoxime, amoxicillin + clavulanic acid, cefaclor, cefuroxime, ofloxacin, cotrimoxazole, ceftriaxone and cefalexin. Gram-positive strains were tested also with erythromycin, while gram-negative bacteria were tested against aztreonam. Cefpodoxime overall activity was well above the effectiveness of the other oral cephalosporins and on the same order as ceftriaxone and ofloxacin. Cefpodoxime proved to be also more active than the combination amoxicillin-clavulanic acid.

In vitro activity of a new quinolone, rufloxacin, against nosocomial isolates

The in vitro activity of rufloxacin (MF 934), a new broad-spectrum fluoroquinolone, was tested against 1,032 gram-positive and gram-negative clinical isolates and compared to that of five other compounds of this class. All quinolones except for ciprofloxacin had limited activity against group A and B streptococci and pneumococci (MIC 90% of 4-64 mg/l) and no activity against enterococci. Most species of the enterobacteriaceae and staphylococci were found to be sensitive to rufloxacin (MIC 90% of 0.5-8 and 2-8 mg/l). Like the other quinolones except for ciprofloxacin, rufloxacin was not active against Pseudomonas aeruginosa. The antibacterial activity of rufloxacin was affected only minimally by an increase in the bacterial inoculum or by alterations in the pH of the medium. In spite of the relatively higher MICs of rufloxacin compared to those of the other quinolones, its favorable pharmacokinetic properties may account for its good clinical efficacy.

Microbiological patterns of four new imidazole derivatives

The authors present an in vitro experimental study concerning the microbiological properties of four imidazole derivatives, with a piperazine group between two benzene rings. Seventy strains of Gram-positive and Gram-negative bacteria, 30 of yeasts, 14 of filamentous fungi and 10 strains of Trichomonas vaginalis were tested. The new compounds revealed a good inhibitory activity against Gram-positive bacteria, yeasts and dermatophytes. These results compare well with those obtained with the other known imidazoles. Moreover any mutagenic activity is absent.

Carumonam's in-vitro activity against gram-negative bacteria and its stability to their beta-lactamases

The in vitro activity of the novel monobactam carumonam (RO17-2301) was evaluated on 311 gram-negative clinical isolates in comparison to aztreonam, cefotaxime, ceftazidime, cefotetan and ceftriaxone. Carumonam showed an antibacterial potency equal to or higher than any other reference compound; in particular it was the most effective against Proteus indole positive and Klebsiella sp. Its antipseudomonal activity was comparable to that of ceftazidime and it showed, together with aztreonam, the highest activity against the Citrobacter, Enterobacter and Escherichia coli isolates. The minimal inhibitory concentrations performed on permeability altered organisms indicated that carumonam has a penetration rate comparable to aztreonam and higher than cefotetan and ceftriaxone. Carumonam demonstrated excellent stability to chromosomal and plasmid-mediated beta-lactamases and that correlated with its antibacterial activity against the producing strains and inoculum size effect.

[Bactericidal and potent antiadhesive activity of sulbenicillin]

Sulbenicillin, a wide broad spectrum penicillin, is active against a lot of gram positive and gram negative bacteria. The AA. studied the activity of this molecule against urinary infections causing germs, by evaluating two parameters: his antiadhesive capability and the Killing curves, in comparison with mezlocillin and piperacillin. An inhibition in adhesive capability of test-germs, due to sulbenicillin was obtained. Furthermore, resulting Killing curves showed more rapidity in action for sulbenicillin than for the two others molecules, versus resistant germs, like P. aeruginosa and S. faecalis.

[Bactericidal activity of octophene]

In this study the bactericidal activity of Clofoctol has been evaluated by "in vitro" technique against gram-positive against gram-positive microorganisms clinically isolated. The results show that MIC of Clofoctol is very close to its bactericidal activity, which could therefore be retained as its main activity. The MBC recovered was 1-8 mcg/ml against strains of Staphylococcus aureus and 2-8 mcg/ml against Streptococcus pyogenes, while the bactericidal activity against Staphylococcus aureus, evaluated at M.B.C., was recovered after 30'.

In-vitro antibacterial activity of Sch 25393, a fluorinated analogue of thiamphenicol

The in-vitro antibacterial activity of a fluorinated analogue of thiamphenicol, Sch 25393, has been evaluated in comparison with chloramphenicol and thiamphenicol. The substitution of an hydroxyl group at position 3 and of two atoms of chlorine with fluorine in the acyl side-chain improves remarkably the antibacterial activity of the compound against strains resistant to chloramphenicol and thiamphenicol because of the production of acetyltransferases, but not against strains resistant because of non-enzymatic mechanisms of resistance. Although itself resistant to the enzymatic inactivation, Sch 25393 is unable to inhibit the acetylation of chloramphenicol and thiamphenicol.