Transferable plasmid mediating resistance to multiple antimicrobial agents in Klebsiella pneumoniae isolates in Greece

OBJECTIVE

To investigate the underlying resistance mechanisms in 10 Klebsiella pneumoniae isolates.

METHODS

Ten K. pneumoniae strains according to distinct bacteriocin typing and REP-PCR, were examined for their plasmid content, their ability to transfer their resistance to aminoglycosides and third-generation cephalosporins, and their production of aminoglycoside-modifying enzymes and beta-lactamases.

RESULTS

Transfer of resistance to the above-mentioned antibiotics as well as to co-trimoxazole and tetracycline in Escherichia coli strain RC 85 at a frequency of 5-106 was achieved for all strains by conjugation. Similar strains harbor a self-transferable multiresistant plasmid (80 kb) with similar EcoRI and HindIII restriction patterns. This plasmid encodes an extended-spectrum beta-lactamase which confers high-level resistance to third-generation cephalosporins and aztreonam. It produces SHV-5 beta-lactamase, as demonstrated by isoelectric focusing and DNA sequencing. Aminoglycoside resistance was co-transferred, and AAC(6')-I, mediating resistance to gentamicin, tobramycin, netilmicin and amikacin, and AAC(3)-I, mediating resistance to gentamicin and sisomycin, were encoded in all isolates and their transconjugants, while APH(3')-I, mediating resistance to kanamycin and neomycin, was encoded in seven strains.

CONCLUSIONS

It appears that a multiresistant transferable plasmid encoding the SHV-5 beta-lactamase, causing unusually high resistance to ceftazidime and aztreonam, and the combination AAC(6')-I + AAC(3)-I of acetylating enzymes causing, also resistance to all clinically available aminoglycosides, is established in K. pneumoniae in Greece.

Interactions of colistin and rifampin on multidrug-resistant Acinetobacter baumannii

The increased incidence of nosocomial infections by multidrug-resistant Acinetobacter spp creates demand on the application of some combinations of older antimicrobials on that species. The in vitro activities of colistin and of rifampin and of their interaction were tested on 39 nosocomial isolates of Acinetobacter baumannii. All isolates were resistant to ampicillin/sulbactam, to 3(rd) and 4(th) generation cephalosporins, to amikacin and to ciprofloxacin. MICs were determined by a microdilution technique and interactive studies between 1x or 4x MIC of colistin and rifampin were performed by the time-kill assay. Rifampin was applied at a concentration of 2 microg/mL which is equal to its mean serum level. All isolates were inhibited by colistin and only 15.2% by rifampin. Synergy between 1x MIC of colistin and rifampin was detected in 15.4% of isolates at 6 h of growth and in 51.3% of isolates at 24 h of growth. Synergy between 4x MIC of colistin and rifampin was detected in 15.4% of isolates at 6 h of growth and in 66.7% of isolates at 24 h of growth. It is concluded that colistin is highly active on multidrug-resistant Acinetobacter spp and its activity on A.baumannii is increased in the presence of rifampin, so that their administration might be proposed for nosocomial infections by these isolates.

In vitro interactions of aminoglycosides with imipenem or ciprofloxacin against aminoglycoside resistant Acinetobacter baumannii

The in vitro interactions between gentamicin, tobramycin, netilmicin and amikacin with imipenem and ciprofloxacin were evaluated by the killing curve technique against 20 clinical isolates of Acinetobacter baumannii highly resistant to aminoglycosides which were susceptible or moderately susceptible to imipenem and resistant or moderately susceptible to ciprofloxacin. Imipenem enhanced killing by gentamicin, tobramycin, netilmicin and amikacin in tests with 9, 12, 10 and 15 strains (45-75%) while ciprofloxacin with 3, 7, 5 and 6 strains (15-35%) respectively. Interaction results were influenced by the height of aminoglycoside minimum bactericidal concentrations (MBCs) but were independent of imipenem or ciprofloxacin MBCs and the presence of aminoglycoside modifying enzymes. It is concluded that enhanced killing after aminoglycoside interaction with imipenem or ciprofloxacin versus A. baumannii cannot be predicted but it should be carefully tested in vitro. The in vivo significance of the reported findings mandates clinical studies in humans.

Comparative in vitro activity of sparfloxacin (AT 4140, RP 64206--SPFX) against 275 multiresistant clinical isolates

The in-vitro activity of sparfloxacin was compared with that of pefloxacin, ofloxacin, ciprofloxacin, imipenem, ceftazidime, gentamicin and amikacin against 275 multiresistant nosocomial clinical isolates. They consisted of Pseudomonas aeruginosa (37), Enterobacter cloacae (42), Acinetobacter anitratus (60), Klebsiella pneumoniae (37) and Staphylococcus sp (99). Minimum inhibitory concentrations (MIC90) and geometric mean MICs for sparfloxacin were as follows (mg/l): P. aeruginosa 128-23.7, E. cloacae 1-0.13, A. anitratus 2-0.14, K. pneumoniae 1-0.08, MRSA 16-0.98, MSSA 0.12-0.03, MRSE 0.25-0.12 and MSSE 0.12-0.05. It is concluded that sparfloxacin was the most potent agent against staphylococci and A. anitratus including strains resistant to the other quinolones while ciprofloxacin was the most potent agent against P. aeruginosa, E. cloacae and K. pneumoniae.

Diet and breast cancer: a case-control study in Greece

A case-control study of the role of diet in the etiology of breast cancer was conducted in Athens, Greece. There are reasons to believe that the diet of the Greek population is characterized by greater heterogeneity than that in most countries where such studies have been undertaken. The case series consisted of 120 consecutive patients with histologically confirmed breast cancer admitted to either of two teaching hospitals over a 12-month period. The controls were 120 patients admitted to a teaching hospital for trauma and orthopedic conditions during the same period. Dietary histories concerning the frequency of consumption of 120 foods and drinks were obtained by interview. Cases reported significantly less frequent consumption of vegetables as a group and, within that group, specifically of cucumber, lettuce and raw carrot. After adjustment for potential external confounding variables and for confounding between food categories, the odds ratio for persons in the highest quintile of vegetable consumers, relative to those in the lowest quintile, was 0.09 with 95% confidence limits 0.03-0.30. That is to say, the lowest quintile of vegetable consumers had about 10 times the breast cancer risk of the highest quintile. For a score based on consumption of only the 3 specified salad items the odds ratio over the extreme quartiles was 0.12 (0.05-0.32). There was no association with consumption of fats and oils, alcohol or coffee, and no significant association with any other major food category (including alcohol and coffee) after adjustment for confounding variables.

Prevalence of diphtheria carriers in a population with disappearing clinical diphtheria

Ten years ago the incidence of diphtheria was relatively high in Greece and a survey of school children had revealed a carrier prevalence of non-toxigenic Corynebacterium diphtheriae of 3,4%. A similar survey undertaken now has revealed that the disease seems to be disappearing. Among 895 school children (6-13 years-old) in seven primary schools of different socioeconomic levels, only seven were carriers of non-toxigenic C. diphtheriae strains, corresponding to a prevalence of 0.8%. Toxigenic strains were not found. All carriers were pupils of the same school, and the carrier state was more frequent during the first three school years. All the carriers were found in a school serving a socioeconomically deprived area. A statistically significant association was found between the prevalence of C. diphtheriae and of other non-pathogenic Corynebacteria.

Comparison of selenite F, Muller-Kauffmann tetrathionate and Rappaport's medium for the isolation of salmonellas from sewage-polluted natural water using a pre-enrichment technique

Three enrichment broths, selenite F, Muller-Kauffmann tetrathionate and Rappaport, were examined for their efficiency in salmonella isolation. The three media, prepared from single ingredients in the laboratory, were compared with their commercial equivalents. Laboratory-prepared media were more efficient for isolating salmonellas from sewage-polluted natural water samples. A pre-enrichment stage using buffered peptone water was employed throughout the investigation. The size of inoculum from the pre-enrichment medium was relevant to successful salmonella isolation. Inocula studied were 1 ml and one loopful (3 mm diameter loop). The smaller inoculum gave better results with Rappaport, the larger with selenite and tetrathionate. Using the optimal inocula, Rappaport was the most efficient enrichment broth of the three fluid media in this study.

Hepatitis B and primary hepatocellular carcinoma in a European population

The prevalence of serological markers of active of past hepatitis-B virus (H.B.V.) infection was determined in 80 Greek patients with primary hepatocellular carcinoma (P.H.C.), 160 age and sex matched controls and 40 patients with metastatic liver cancer (M.L.C.). The relative risk of the various patterns of H.B.V. serological markers for P.H.C. was calculated. Active H.B.V. infection, as indicated by positive tests for hepatitis-B surface antigen (HBsAg), or antibody to hepatitis-B core antigen (anti-HBc) without antibody to HBsAg) (anti-HBs), was associated with P.H.C. (relative risk 10.4) but not with M.L.C. (relative risk 1.2). Patients without markers and those who had recovered from hepatitis B (anti-HBs-positive) had approximately the same low risk for P.H.C. (relative risk 0.8). Active infection was more common in P.H.C. patients with co-existing cirrhosis than in those without cirrhosis (67% versus 26%). Thus the relationship between active hepatitis B and P.H.C. seen in African and Asian populations is now seen in a European Caucasian population with different racial, environmental, and dietary circumstances.

Incomplete right bundle branch block and vital capacity

Right bundle branch block (RBBB) is occasionally encountered in young persons who lack any other evidence of overt cardiac disease (Hiss and Lamb, 1962; Lancaster, Schechter, and Massing, 1972). The block may be complete or incomplete, the latter being more common. Right bundle branch block has been studied in relation to body weight, obesity, serum cholesterol and glucose levels, and blood pressure, but the results have been negative (Ostrander, 1964; Kannel et al., 1962). Data presented here suggest that incomplete RBBB is related to vital capacity.