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Objectives: Little is known regarding outcomes and optimal therapeutic regimens of infections caused by Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) resistant to ceftazidime/avibactam (CZA) and susceptible to meropenem (MEM). Although susceptible to MEM in vitro, the possibility of developing MEM resistance overtime is a concern. We describe the clinical characteristics of patients with colonization/infection due to KPC variants with a focus on the in vitro activity of fosfomycin (FOS)-containing combinations., Methods: Patients with colonization/infection due to a KPC variant were included. Fosfomycin 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: eight with infection [four with ventilator-associated pneumonia and four with bloodstream infections] and three with colonization. Previous therapy with CZA was administered to all patients (with a mean cumulative duration of 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 three 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., Conclusions: Detection of KPC variants 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 be a valuable combination option for KPC variants, while MVB may be considered in monotherapy. 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 of concern, which may lead to therapeutic failure in clinical practice. In these cases, the addition of fosfomycin to meropenem, or a more potent antibiotic, such as meropenem/vaborbactam, may be valuable therapeutic options., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

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., (Copyright © 2015 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

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.

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.

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.

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.

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.

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.

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.

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.

Infections of Rhodococcus equi, a well-known pathogen in animals which causes cavitated pneumonia similar to that caused by mycobacteria, were studied in three HIV-infected patients. This microorganism was isolated in the bronchoalveolar washings of two patients and in the sputum of the third. In two patients, Rh. equi represented the first clinical opportunistic manifestation of HIV disease. One patient died of concomitant Pneumocystis infection. The eradication of the microorganism occurred in two out of three patients. It was found that no isolates were resistant to erythromycin, claritromycin, rifampin, vancomycin, teicoplanin, imipenem, gentamycin or azithromycin (MIC values < or = 0.1 microgram/ml). Moreover, the quinolones (ciprofloxacin and ofloxacin) were found to be less effective, whereas neither the beta-lactam antibiotics nor chloramphenicol were effective therapy for this microrganism. At least two antimicrobial agents should be given contemporaneously to treat these infections for a period of up to several months. Our results suggest that the combinations erythromycin + rifampin or imipenem + teicoplanin are the most effective treatments in Rh. equi infections.

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.

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.

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.

The authors have compared the antimicrobial resistance patterns and plasmid profiles of Gram-negative isolates in an intensive care unit over a 7-month period in order to identify epidemiologically related isolates. Bacterial plasmids were found to be valuable markers for the comparison of strains of nosocomial Gram-negative bacilli. Thirty-nine mechanically ventilated patients in an ICU were included. From bronchoaspiratus, the authors isolated 58 strains of Gram-negative bacilli (24 Ps. aeruginosa and 34 Enterobacteria). Common plasmids were found in most Enterobacteria. The interspecies plasmid exchange suggests that interstate spread of these strains may have occurred. Twenty-six Enterobacteria carried plasmids, 11 of which proved transmissible. The R-factors were transferred to other genera that were isolated in the hospital, thereby adding to the pool of multiresistant nosocomial isolates. Larger plasmids transferred ampicillin and carbenicillin resistance, while gentamycin and cephalotin resistance was carried by smaller plasmids. Only 4 Ps. aeruginosa carried plasmids, one of which was transmissible. Pseudomonas plasmid DNA is extracted with difficulty by the simple lysis method, due to the roughness of the colonies. All Pseudomonas isolates belonged to the same biotype which can be regarded as an epidemiological marker. Therefore, plasmid profiling is a useful tool for epidemiological surveillance of Enterobacteria and is a good method for determining the relatedness of isolates in a nosocomial environment.

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.

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.

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

Pneumococcal serotyping by quellung reaction has been performed in five Italian areas on 267 strains, isolated from throat swab, sputum, blood, liquor, etc. 37 serotypes have been identified. The most frequent types resulted 19, 6, 3, 20, 9, 4 (in 50% of total samples), with no difference from those detected in other European countries. The proportion of type 19 was the highest among all age group, in four out of five different areas and in bacteremic pneumonia and meningitis. 36 strains were isolated from infection sites among which type 19 resulted more frequent than in isolates from throat swab and sputum (27.7% versus 16.1%). Pneumococcal serotyping should be routinely done in the light of forthcoming use of polysaccharide vaccine.

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.