Ceftazidime/avibactam-resistant meropenem-susceptible KPC-producing Klebsiella pneumoniae: analysis of cases and evaluation of in-vitro activity of fosfomycin-containing combinations

BACKGROUND

Little is known regarding outcomes and optimal therapeutic regimens of infections caused by KPC-producing Klebsiella pneumoniae (KPC-Kp) resistant to ceftazidime/avibactam (CZA) and susceptible to meropenem (MEM). Although in-vitro susceptible to MEM, the possibility of developing MEM resistance overtime is a concern. We described the clinical characteristics of patients with colonization/infection due to KPC-variant with a focus on the in-vitro activity of fosfomycin (FOS)-containing combinations.

MATERIALS/METHODS

Patients with colonization/infection due to KPC-variant were included. FOS susceptibility was performed by agar dilution method. Synergistic activity of FOS-based combinations was evaluated by gradient strip-agar diffusion method. The emergence of in-vitro MEM resistance was also tested.

RESULTS

Eleven patients were included, 8 with infection [4 ventilator-associated pneumonia, 4 bloodstream infections], 3 with colonization. A previous therapy with CZA was administered to all the patients (mean cumulative duration 23 days). All subjects with infection received meropenem, in monotherapy (n=4) or with amikacin (n=2) or fosfomycin (n=2) and achieved clinical cure. A new CZA-susceptible and MEM-resistant KPC-Kp strain was subsequently isolated in 3 patients (27.3%). Meropenem/vaborbactam (MVB) showed high in-vitro activity, while FOS+MEM combination was synergistic in 40% of cases. In-vitro resistance to MEM was observed, with maintenance of CZA resistance.

DISCUSSION

Detection of KPC-variant may occur within the same patient, especially if CZA has been previously administered. Although clinical success has been obtained with carbapenems, the emergence of MEM resistance is a concern. Fosfomycin plus meropenem is synergistic and may represent a valuable combination option for KPC-variant, while MVB may be considered in monotherapy.

IMPORTANCE

The detection of KPC-variants in an endemic setting for KPC-Kp represents a worryingly emerging condition. The optimal therapeutic approach is still unknown and the development of meropenem resistance is a concern, which may finally lead to a therapeutic failure in the clinical practice. In these cases, the addition of fosfomycin to meropenem or a more potent antibiotic such as meropenem/vaborbactam may represent valuable therapeutic options.

Bactericidal and synergistic activity of double-carbapenem regimen for infections caused by carbapenemase-producing Klebsiella pneumoniae

Available therapeutic options against carbapenem-resistant Klebsiella pneumoniae (CR-Kp) are limited because of the high level of resistance to other antimicrobial classes including polymyxins. The double-carbapenem regimen has been recently considered a possible therapeutic strategy. In the present study, we evaluated the in vitro bactericidal and synergistic activity of a double-carbapenem regimen consisting of ertapenem plus high-dose meropenem in a series of patients with healthcare-associated CR-Kp infections in whom the use of colistin was not indicated because of potential nephrotoxicity and/or resistance. In vitro synergy was evaluated using checkerboard and killing studies. A total of 15 patients were included in the study, with sepsis, severe sepsis and septic shock found in two (13.3%), five (33.3%) and one (6.7%) patients, respectively. Overall, the clinical/microbiological response was 12/15 (80%). Synergy was observed in 11/14 (78.6%) isolates using the checkerboard method whereas in killing studies 12/14 (85.7%) and 14/14 (100%) strains were synergistic and bactericidal at 24 h at concentrations of 1 × MIC MEM+1 × MIC ERT and 2 × MEM+1 × MIC ERT, respectively, with a significant decrease of log CFU/mL compared with other combinations (p <0.0001). The double-carbapenem regimen showed clinical and in vitro effectiveness in patients with CR-Kp infections.

Study of methicillin-resistant Staphylococcus aureus (MRSA) carriage in a population of HIV-negative migrants and HIV-infected patients attending an outpatient clinic in Rome

BACKGROUND

Migration and HIV infection are known risk factors for methicillin-resistant Staphylococcus aureus (MRSA) carriage and infection. The aim of the study was to analyze the prevalence of MRSA nasal colonization in a high risk population of HIV-negative migrants and HIV-infected subjects. Secondary aim was to investigate over time MRSA carriage prevalence in HIV-infected subjects.

METHODS

During the study period (January-June 2008), nasal swabs were collected from 96 HIV-negative migrants and 63 HIV-infected patients. A group of 68 seropositive subjects was additionally screened for MRSA carriage in 2012. Subjects were evaluated for HIV status, previous antibiotic use or hospitalization, soft tissue and skin infections (SSI), nationality and work conditions. The swab specimens were plated and incubated for 24-h under static condition at 37 degrees and then identified as S. aureus by using standard methods.

RESULTS

A total of 227 subjects, 131 HIV-infected adults (63 in 2008 and 68 in 2012) and 96 HIV-negative migrants, were analyzed. Overall, 71/227 (31.2%) were S. aureus carriers: 34 out of 131 (25.9%) among HIV infected subjects and 37 out of 96 (38.5%) among migrants. Two MRSA were detected in HIV-infected patients (2.8%). Between 2008 and 2012 there was an increase of MRSA carriage in HIV+ group (p=0.49). No statistically significant differences were found between S. aureus carriers and no-carriers in terms of CD4+ cell count, TMP/SMX prophylaxis, previous antibiotic use or hospitalization, nationality and duration of stay in Italy. Among HIV+ patients there was a higher prevalence of SSI in MSSA carriers compared with no carriers (25% vs 4%, p=0.028). In the migrants group, having a job based on a close human contact was significantly associated with S. aureus colonization (p=0.0038).

CONCLUSIONS

Despite of the high prevalence of S. aureus isolation (31.2%), the present study showed the low rate of MRSA carriage in a high risk population. The main factor associated with S. aureus colonization was a close human contact rather than the HIV status and the condition of being migrant.

Helicobacter pylori: determinant and markers of virulence

In this review, we examine the main virulence determinants in Helicobacter pylori (Hp) strains and the correlation between these and the different diseases following Hp infections. We also discuss the host response to Hp and the implications and advantages of the development of non-invasive pre-endoscopy screening of molecular and serological markers associated with Hp virulence and disease progression putting an emphasis on new screening techniques such as the Luminex – X multi analytes profiling technology and the multiplex PCR.

Activity of D-carnitine and its derivatives on Trypanosoma infections in rats and mice

Little progress has been made in the treatment of African trypanosomiasis over the past decades. L-carnitine has a major role in glycolysis-based energy supply of blood trypanosomes for it stimulates constant ATP production. To investigate whether administration of the isomer D-carnitine could exert a competitive inhibition on the metabolic pathway of the L-form, possibly resulting in parasite replication inhibition, several formulations of this compound were tested on Trypanosoma lewisi and T. brucei rhodesiense in rodent models. High oral dosages of D-cornitine inner salt and proprionyl-D-carnitine were not toxic to animals and induced about 50% parasite growth inhibition in reversible, i.e. competitive, fashion. A putative mechanism could be an interference in pyruvate kinase activity and hence ATP production. Considering both, lack of toxicity and inhibitory activity, D-carnitine may have a role in the treatment of African trypanosomiasis, in association with available trypanocidal drugs.

Reduced bactericidal activity against Staphylococcus aureus and Pseudomonas aeruginosa of blood neutrophils from patients with early adult respiratory distress syndrome

This study investigated the bactericidal capability of circulating neutrophils from blunt trauma patients admitted to an Intensive Care Unit against Staphylococcus aureus and Pseudomonas aeruginosa. Among those patients, two groups were considered and compared: patients who developed adult respiratory distress syndrome (ARDS) and patients who developed only pneumonia. Peripheral blood samples were drawn as soon as a diagnosis of pneumonia or ARDS was made, followed by the isolation of neutrophil cells and assessment of bacteria phagocytosis and killing. The results demonstrated that in patients with ARDS, phagocytosis and killing efficiency were significantly impaired in comparison with patients with pneumonia and healthy controls. A possible dysregulation of reactive oxygen species production involving the release of humoral mediators in early ARDS may be involved.

Antimicrobial investigation of semipurified fractions of Ginkgo biloba leaves

A total methanolic extract of Ginkgo biloba leaves was fractionated by solvent partition using ethyl acetate (fraction A), n-butanol (fraction B) and water (fraction C). The antimicrobial activity of the three fractions was evaluated using a number of Gram-positive and -negative bacteria and yeasts. The apolar fraction A appeared to be the most interesting because of its activity against several microorganisms; this fraction was further separated by high performance liquid chromatography, and shown to contain substances with strong inhibitory activity against Enterococcus faecalis 31, different from the major known chemical components of G. biloba leaves.

Antimicrobial activity of fluoroquinolones and other antibiotics on 1,116 clinical gram-positive and gram-negative isolates

A total of 1,116 clinically isolated strains belonging to Staphylococcus aureus (200), Staphylococcus epidermidis (200), Streptococcus pneumoniae (20), Escherchia coli (200), Klebsiella spp. (177), Serratia marcescens (22), Pseudomonas aeruginosa (224), Haemophilus influenzae (35) and Salmonella (38) from the Department of Infectious Diseases, La Sapienza University in Rome (Italy) were tested against three fluoroquinolones (ofloxacin, ciprofloxacin and levofloxacin) and 10 other antibiotics (augmentin, ampicillin, cefaclor, cefixime, cefotaxime, cotrimoxazole, gentamicin, minocycline, oxacillin and vancomycin). Fluoroquinolones inhibited essentially about 100% of H. influenzae, Salmonella and S. pneumoniae, more than 75% of Staphylococcus including methicillin-resistant strains, and about 90% of Enterobacteriaceae and 50% of P. aeruginosa. Minimal inhibitory concentration values ranged from < 0.015 to > 32 micrograms/ml for Klebsiella, S. aureus and epidermidis, E. coli and P. aeruginosa; from < 0.015 to 2 micrograms/ml for Salmonella; from 0.03 to 16 micrograms/ml for Serratia; from < 0.015 to 1 microgram/ml for Haemophilus; and from 0.5 to 2 micrograms/ml for S. pneumoniae. Levofloxacin and to a lesser extent ofloxacin and ciprofloxacin, generally exhibited a greater activity than the other agents against both Gram-positive and Gram-negative bacteria. Regarding the distribution of resistant strains in Italy, we found a peculiar pattern of resistance as far as E. coli and P. aeruginosa were concerned. Quality control parameters are also summarized. S. epidermidis resulted as a new emergent pathogen especially in immunocompromised patients and its level of sensitivity has been modified over the last few years. In fact, the percentage of resistant strains to antibiotics or the percentage of methicillin-resistant isolates (in our study 35%), has gradually increased. Levofloxacin and ofloxacin showed good activity against staphylococcal strains compared with the majority of other antibiotics. These results suggest that the newer quinolones are promising antimicrobial agents for various infections.

The influence of the SOS response on the activity of 4-quinolones and zidovudine against some strains of Enterobacteria

The 4-Quinolones are known to induce the SOS response. This should also be the case with AZT (Zidovudine) which has the same bactericidal mechanism. SOS response might make the bacteria more sensitive or more resistant to subsequent doses of quinolones and AZT. NA (Nalidixic acid), the first quinolone of the early 1960s, sensitises a strain of E. coli isolated from the urine of patients with cystopyelitis and the E. coli AB1157 wild type strain which is a well-known SOS inducer. In this case, the SOS system is not involved but only the recombination repair mechanisms which make the bacteria more susceptible to further damage by NA. On the contrary, CPX (Ciprofloxacin) protects E. coli from further exposure to antibiotics. Therefore the SOS response induction assists the bacteria in recovering from the DNA damage caused by CPX. The SOS response induced by AZT in the tested E. coli strains does not seem to either contribute to the lethality of the drug or to be involved in protecting bacteria from the damage caused by AZT. In fact, the percentage of killing was the same for both pre-treated and non pre-treated bacteria (p = 0.5). On the contrary, it was found that in Salmonella typhimurium belonging to blood of a patient with recurrent bacteriaemia, the CPX added to pre-treated bacteria with AZT was less lethal than when it was added to non pre-treated bacteria. The SOS response, in this case, protects bacteria from the damage caused by AZT.

["Killing" of pseudomonas aeruginosa isolated from patients with critical post-operative complications. Effect of various antibiotics]

We undertook this study to estimate phagocytic killing by neutrophils (PMNs) of Pseudomonas aeruginosa pre-exposed to sub-inhibitory concentration of Amikacin and Imipenem. In particular, we have isolated bacteria from endotracheal aspirates of post-operative patients mechanically ventilated admitted to an ICU with respiratory failure. PMNs were obtained both from these patients (Group A, n. 6) as well as from subjects submitted to surgery with uncomplicated post-operative period (Group B, n. 8). From specimens tested, 6 strains of Pseudomonas aeruginosa were isolated. Results showed that the rate of killing of bacteria treated with Amikacin was no different from that of untreated bacteria, whichever the source of PMNs, either from Group A or Group B patients. On the other hand, the microbicidal effect on P. aeruginosa exposed to Imipenem was significantly enhanced when PMNs were obtained from Group B patients. In the mixture bacteria, Imipenem and PMNs obtained from Group A the rate of killing was low, similar to the controls without antibiotics. Such a finding suggests a possible impairment of PMNs due to the critical disease and in some way responsible for the host adverse interaction between granulocytes, antibiotics and pathogens. The underlying mechanisms remain to be clarified and further studies are required to understand the possible clinical implications.

Incidence of bacterial colonization in the throat and in urines at paediatric age with evaluation of sensitivity to common antibiotics

OBJECTIVES

To evaluate the incidence of bacterial colonization in the throat and in urines of children admitted to a paediatric ward in the year 1994. To test the sensitivity of isolates on the most common antibiotics used in therapy.

METHODS

The investigation was carried out on a group of 270 children (125 male and 145 female), aged between 3 months and 12 years, hospitalized with feverish infectious pathology in the department of infectious and Tropical Diseases of the University "La Sapienza" of Rome. The cultures of the throat swabs and on urines were performed on the admission of the children before the beginning of the therapy.

RESULTS

The throat-swab cultures showed pathogenous microrganisms in 232 samples (85.9%) with a slight prevalence of Gram-negative bacteria (122) with respect to Gram-positive (110) and saprophytic microbial flora (38). The urine cultures proved to be positive in 81 cases (30%) with a prevalence of Gram-negative (56) above Gram-positive isolates (25).

CONCLUSIONS

The two/thirds of paediatric patients hospitalized in an Infectious Diseases Department appeared to be colonized in the upper respiratory tract, whereas in about 10% of them a marked bacteriuria was clearly evident, often in the absence of specific symptoms. A few isolates either from the throat or from urines, showed resistance to the common antibacterial agents.

Type frequency and antimicrobial susceptibility of Mycobacterium avium-intracellulare complex strains isolated in Italy from AIDS and non-AIDS patients

Typing of the glycopeptidolipid antigens performed by thin layer chromatography on 59 Mycobacterium avium-intracellulare (MAC) strains isolated in Italy from AIDS patients showed that the most frequent types were 1, 4, 3, 8, and 21 (24, 19, 14, 14 and 8% of the strains, respectively). Among non-AIDS patients, types 1, 4 and 8 were also frequently found. The antimicrobial susceptibility tested in agar and/or liquid media to a panel of drugs indicated in clofazimine and rifabutin effective agents against both AIDS and non-AIDS strains. The data obtained show that MAC type distribution in Italy appears to be different from that reported for other countries. No major differences in drug susceptibility between AIDS and non-AIDS related strains were found.

Activity of seven antimicrobial agents, alone and in combination, against AIDS-associated isolates of Mycobacterium avium complex

The activity of seven antimicrobial agents (and five two-drug combinations and five three-drug combinations) was investigated against 37 clinical isolates of Mycobacterium avium recovered from blood cultures of AIDS patients. The susceptibility tests were performed in Middlebrook 7H12 broth using a radiometric method. MICs of amikacin, ciprofloxacin, clarithromycin, clofazimine, ethambutol, rifabutin and sparfloxacin were determined. Five antimicrobial agents were tested in combination with clarithromycin and also with clarithromycin plus amikacin to look for possible synergic activity. Synergic activity in combination with clarithromycin and with clarithromycin plus amikacin, was detected for rifabutin (54% and 51% of isolates, respectively), clofazimine (38% and 35%), ethambutol (16% and 32%), ciprofloxacin (8% and 14%) and sparfloxacin (3% and 8%). No antagonism was observed. We conclude that clarithromycin is an essential component in the chemotherapy of M. avium complex disease.

Rapid detection of mycobacteria by combining a radiometric detection system with DNA probes

Forty-four Mycobacterium-spp. were isolated in 33 patients from an infectious diseases ward. All patients were HIV-positive and most of them were drug-abusers. M. avium-intracellulare was the most common type of MOTT (Mycobacteria other than tuberculosis) detected and the only microorganism isolated in patients with mycobacteriaemia. The radiometric method performed by the Bactec system enhanced the isolation rate of mycobacteria, especially from the bloodstream. The Gen-probe DNA hybridization system proved to be rapid diagnostic tool for the identification of strains.

In vitro activity of zidovudine alone and in combination with ciprofloxacin against Salmonella and Escherichia coli

The in vitro antibacterial activity of zidovudine alone and in combination with ciprofloxacin was investigated. Zidovudine showed a good activity against Escherichia coli and Salmonella (MIC range 0.5-8 micrograms/ml and 1.5-62 micrograms/ml respectively) isolated from biological samples of HIV-infected patients. These strains proved to be extremely susceptible to ciprofloxacin alone. The interaction between zidovudine and ciprofloxacin ranged from additive activity to indifference. No antagonism was observed: the FIC index for every combination resulted < or = 1.5. The addition of AZT 1 mg/l (clinically achievable plasma concentration after therapeutic doses of 1200 mg/day) did not affect the bactericidal activity of ciprofloxacin; on the contrary, in some cases we observed an increase of bactericidal effect of the quinolone. These data have to be considered in patients with AIDS who can be treated concomitantly with zidovudine and ciprofloxacin.

[Clinical-therapeutic considerations in a case of miliary tuberculosis in an indonesian girl]

The authors describe the case of widespread miliary tuberculosis, that arose in a ten year-old Indonesian girl of middle-class, who has been living in Italy from about three years. The girl was probably contaminated by a subject belonging to the same ethnic-social community, who was affected with tubercular disease. The diagnosis was effected on the ground of: clinical picture including continued-remitting fever, a loose cough, asthenia, anorexia, weight reduction, aching tumefaction on the left side of the neck; isolation of Mycobacterium tuberculosis from the expectoration, blood, urine, and a lymph node located on the left side of the neck; radiological picture that revealed a widespread miliary tuberculosis. In spite of polychemotherapy with isoniazid , rifampicin, pirazinamide, and streptomycin that was subsequently replaced by ethambutol, the course of the illness worsened and it was characterized with fever, cachexia, respiratory insufficiency and repeated episodes of pneumothorax. For such reasons on the ground of susceptibility to the antibiogram amikacin and ciprofloxacin, as well as glucocorticoids to limit the fibrousness, were added to the specific therapy that was already being out. For persisting of relapsing pneumothoraxes, the patient underwent a thoracoscopy and plerodesis with talcum powder. After four months of antitubercular therapy, the research of M. tuberculosis resulted negative in the expectoration, urine, bronchus-alveolar washing liquid and blood, in addition to improvement in general state of health with remission of fever was noticed.

Activity of antimicrobial agents against Mycobacterium avium-intracellulare complex (MAC) strains isolated in Italy from AIDS-patients

Twenty-five strains of Mycobacterium avium-intracellulare (MAC) isolated from acquired immunodeficiency syndrome (AIDS) patients in three medical centres in Italy have been studied. Serotyping performed on eighteen strains showed various serovars within either M. avium or M. intracellulare serotypes and with serovars 1 and 21 being the most prevalent (four strains for each serovar). Among fourteen drugs used for testing the antibiotic sensitivity, rifapentine, rifabutin and clofazimine showed to have the best in vitro activity. In an ex vivo model of infection using peritoneal resting macrophages from the C57BL/6 mouse, the intracellular viability of a strain of M. avium (strain 489, serovar 3) was reduced by clofazimine, amikacin, ciprofloxacin, rifabutin and clarithromycin (99, 98, 93, 89 and 69%, respectively), thus indicating for clofazimine a good correlation between in vitro and ex vivo activity.

In vitro activity of clarithromycin alone or in combination with other antimicrobial agents against Mycobacterium avium-intracellulare. Complex strains isolated from AIDS patients

The activity of clarithromycin and five other antimicrobial agents, namely amikacin, rifampicin, rifabutin, clofazimine and ciprofloxacin, was assessed both by an agar dilution and a radiometric method in broth on 11 Mycobacterium avium-intracellulare complex (MAC) strains, recently isolated from AIDS patients. Minimum inhibitory concentrations (MICs) radiometrically determined were, in general, several times lower than MICs assessed in agar, probably because of a partial degradation of antimicrobials during the long incubation period needed for tests in solid medium. When tested in broth, rifabutin and clofazimine showed very low MICs 90 (0.24 and 0.78 microgram/ml, respectively). Ciprofloxacin and clarithromycin also had MICs90 in the range of peak serum levels (1.93 and 3.76 micrograms/ml, respectively). Moreover, all these antimicrobials are known to concentrate several times in macrophages. MICs90 were higher for amikacin (11 micrograms/ml) and for rifampicin (8 micrograms/ml). When clarithromycin was tested against three MAC strains in combination with another drug, it showed a synergistic effect only when combined with rifampicin. Some synergistic effect was observed also when combining clarithromycin with rifampicin and amikacin, whereas in combination with rifabutin and clofazimine there was only an additive effect.

Evaluation of vaginal microflora in patients infected with HIV

HIV infection is thought to exacerbate the virulence of normal saprophytic vaginal microflora. We studied the vaginal ecosystem of HIV patients to detect the quantitative and qualitative variation of vaginal microorganisms. 15 patients (5 with AIDS and 10 with ARC) were investigated. Vaginal candidiasis was more frequent in this group than in the control groups. Gardnerella was present in 60% of patients generally in association with anaerobic bacteria and Mycoplasma. Among anaerobia, Bacteroides sp and other Gram-negative rods were the most common bacteria. Neisseria gonorrhoeae was absent in all patients tested. Chlamydia trachomatis was recovered in two out of the 15 HIV-positive patients. Aerobic Gram-negative flora was 100-fold that of the control group and anaerobic Gram-negative flora 10-fold.

Cryptococcal meningitis and toxoplasma encephalitis in an AIDS patient

A black heterosexually HIV-infected woman, initially presented with cryptococcal meningitis (satisfactorily responding to fluconazole treatment), which was soon followed by lethal cerebral toxoplasmosis.

Erythromycin, miocamycin and clindamycin towards adhesivity and phagocytosis of gram-positive bacteria

To estimate the antibacterial activity of sub-MIC concentrations of Erythromycin and Miocamycin in the mucosal surfaces, we studied the adhesivity of Gram-positive pathogenic strains (S. pyogenes, S. aureus) towards oral and urinary epithelial cells. Erythromycin strongly inhibits the adhesivity of Staphylococci to oral cells (50% of inhibition) and to a lesser extent the adhesivity of Streptococci (21%), while Miocamycin reduced the adhesivity of Staphylococci by about 16%. In some cases, an increase in the adhesivity on urinary cells was found mainly for Miocamycin. Therefore Erythromycin, at sub-MIC concentrations, is able to induce a marked reduction in the adhesivity of Staphylococci and Streptococci; this may interfere with the invasivity and subsequent pathogenicity of these bacteria. As far as phagocytosis is concerned, one strain of enterotoxic coagulase + S. aureus bearing A-protein on its surface but lacking the capsule was taken into consideration. The presence of A-protein induces resistance to phagocytosis and opsonization by normal serum. The addition of antibiotics which inhibit protein biosynthesis, such as Clindamycin, Miocamycin and Erythromycin, increases either uptake of this strain or intracellular killing. In particular Clindamycin and Erythromycin, at sub-MIC concentrations, are able to affect the interaction of Staphylococcus with phagocytic cells.

[Research on staphylococcal enterotoxin B by dot immunobinding assay (DIB). Preliminary observations]

A recently developed immunoenzymatic technique, the Dot Immunobinding assay (DIB), has been applied to the rapid detection of staphylococcal enterotoxin B in filtered culture supernatants. The test has been shown to be highly sensitive and specific, easy to perform and rapid (only 4 hours). The use of nitrocellulose paper as the solid phase allows the exact standardization of the amount of antigen employed and it avoids the overnight incubation usually necessary with the conventional enzyme-linked immunosorbent assay (ELISA).

[Combined surgical and medical treatment of pilonidal cysts and fistulae as prevention of recurrence]

The possibility of reducing the incidence of postoperative recurrences of pilonidal fistulas by using preoperative doses of Cephoxitine and primary surgical closure is described.

A preliminary report on the immunological responses after oral vaccine (Ty 21a)

Humoral and cell-mediated immune responses, specific for lipopolysaccharide (LPS), were evaluated before and after oral immunization with the Ty 21a strain of Salmonella typhi in a group of healthy volunteers. No rise in seric and foecal antibody titres, detected by the ELISA technique, was seen after vaccination. On the contrary, we were able to demonstrate the development of specific cell-mediated immunity, as assayed by the leukocyte migration inhibition test, 21 days after vaccination. This conversion was still present 40 days after the last dose of vaccine. We believe that the Ty 21a strain of S. typhi, recently proposed for immunization against typhoid fever and based on the use of live micro-organisms, is effective due to its ability to induce specific cell-mediated immunity.

Evaluation of automatic antimicrobial susceptibility testing with the MS-2 system

We present the results of sensitivity of 191 Gram-negative bacteria towards the following antibiotics: aminoglycosides (amikacin, gentamicin, tobramycin, netilmicin), cephalosporines (moxalactam, cefotaxime, ceftazidime) and piperacilline obtained by agar diffusion method (Kirby-Bauer) versus automatic system MS 2 Abbott. Essential accord expressed in percentage is for amikacin 96%, for gentamicin 93%, for moxalactam 91%, for tobramycin 95%, for cefotaxime 92%, for piperacilline 89%, for netilmicin 90%, for ceftazidime 92. Full accord gives more discrepant results especially for cephalosporins. For aminoglycosides no significative differences were observed between the two methods. For cephalosporins the incidence of discordance was a little more high. A better sensitivity was obtained by Kirby-Bauer method versus automatic system, which can be considered a therapeutical tool as it furnishes rapidly (4 hours) MIC values, useful to establish antibiotic doses.

[Study of the minimum inhibiting concentration of a new cephalosporin (HR 756): comparative data with other beta-lactamic antibiotics]

HR 756 is a new beta-lactamase resistant cephalosporin. The activity of HR 756 was compared in vitro to that of cefamandole, cefoxitine, cefuroxime and cephalothin. A concentration of 1 microgram/ml inhibited practically all isolates of E. coli, Salmonella, Shigella, Proteus indole + and indole --, Klebsiella, etc. A lower activity in vitro has been found regarding to Enterobacter, Serratia, Citrobacter and Pasteurella. The cefotaxime has some anti-Pseudomonas activity at concentrations of 7.5-15 micrograms/ml. For most Gram-negative organisms, HR 756 was most active. The cephalothin and the cefoxitine have resulted more active regard to Staph. aureus and Bacteroides fragilis, respectively.

A multicentric study for serotyping and susceptibility to antibiotics of pneumococci in Italy

A multicentric study of the incidence of pneumococcal serotypes was recently carried out in five different geographical areas in Italy. Two hundred and sixty-seven strains were typed using the quellung reaction with monospecific antisera, but only 28 of these were isolated directly from the site of infection. The most frequent serotypes were 19, 6, 3, 9, 4, 1 and 18 without remarkable differences regarding the area, age of patients and site of isolation. It was found that 60.3% of the serotypes isolated from all sources and 67.8% of those isolated from the sites of infection are contained in the currently used antipneumococcal vaccine. Antibiotic resistance was found versus aminoglycosides (34.9%), tetracycline (28.3%), chloramphenicol (5.2%) and penicillin (3.3%). Cefoxitin appeared to be the antibiotic to which the pneumococci were most susceptible. Only two types, 19 and 16, resulted resistant to all the antibiotics.