Successful treatment with intravenous colistin for sinusitis, orbital cellulites, and pneumonia caused by multidrug-resistant metallo-beta-lactamase-producing Pseudomonas aeruginosa in a patient with acute myeloid leukemia

The incidence of multidrug-resistant Pseudomonas aeruginosa (MDRPA) and metallo-beta-lactamase (MBL)-producing P. aeruginosa has increased worldwide. The treatment options are limited for infectious diseases caused by these two organisms. The use of colistin has been of recent interest in cases involving both types. We report the case of a 74-year-old man with acute myeloid leukemia who was successfully treated with intravenous colistin for maxillary sinusitis and orbital cellulites due to MBL-producing MDRPA during neutropenia, and then for pneumonia caused by the bacteria after the recovery of neutrophil counts.     

Clarithromycin is an effective immunomodulator when administered late in experimental pyelonephritis by multidrug-resistant Pseudomonas aeruginosa

Background  

To apply clarithromycin as an immunomodulatory treatment in experimental urosepsis by multidrug-resistant Pseudomonas aeruginosa.     

Pseudomonas aeruginosa bloodstream infections: risk factors and treatment outcome related to expression of the PER-1 extended-spectrum beta-lactamase

Background  

Bloodstream infection (BSI) due to Pseudomonas aeruginosa (Pa) has relevant clinical impact especially in relation to drug resistance determinants. The PER-1 extended-spectrum beta-lactamase (ESBL) is a common enzyme conferring high-level resistance to anti-pseudomonal cephalosporins. Risk factors and treatment outcome of BSI episodes caused by PER-1-positive Pa (PER-1-Pa) strains were compared to those caused by ESBL-negative Pa isolates (ESBL-N-Pa).     

Pseudomonas aeruginosa biofilm formation in the cystic fibrosis airway

The cystic fibrosis (CF) lung is chronically inflamed and infected by Pseudomonas aeruginosa, which is a major cause of morbidity and mortality in this genetic disease. Although aerosolization of Tobramycin into the airway of CF patients improves outcomes, the lungs of CF patients, even those receiving antibiotic therapy, are persistently colonized by P. aeruginosa. Recent studies suggest that the antibiotic resistance of P. aeruginosa in the CF lung is due to the formation of drug resistant biofilms, which are defined as communities of microbes associated with surfaces or interfaces, and whose growth is facilitated by thick and dehydrated mucus in the CF lung. In this review, we discuss some of the current models used to study biofilm formation in the context of biotic surfaces, such as airway cells, as well as the contribution of host-derived factors, including DNA, actin and mucus, to the formation of these microbial communities. We suggest that better in vitro models are required, both to understand the interaction of P. aeruginosa with the host airway, and as models to validate new therapeutics, whether targeted at bacteria or host.     

Inhibition of fungal growth by Pseudomonas aeruginosa and Pseudomonas cepacia isolated from patients with cystic fibrosis

This study was undertaken because of the infrequency of infections due to Candida species in patients with cystic fibrosis despite their extensive treatment with broad-spectrum antibiotics. In vitro susceptibility studies revealed significant inhibition of 11 strains of fungi known to infect human beings by 10 strains of Pseudomonas aeruginosa and nine strains of Pseudomonas cepacia isolated from the sputum of patients with cystic fibrosis. The fungi were Candida krusei, Candida keyfr, Candida guillermondii, Candida tropicalis, Candida lusitaniae, Candida parapsilosis, Candida pseudotropicalis, Candida albicans, Torulopsis glabrata, Saccharomyces cerevisiae and Aspergillus fumigatus. Inhibition of fungal growth by Escherichia coli (NCTC 10418), Staphylococcus aureus (NCTC 6571) and Haemophilus influenzae (NCTC 11931) could not be demonstrated. The continued presence in the sputum of patients with cystic fibrosis of strains of P. aeruginosa and P. cepacia, which produce antifungal substances, may inhibit growth of Candida species and so prevent overt Candida infections. A. fumigatus would seem to be the most important fungus causing disease in patients with cystic fibrosis. It is therefore interesting to note that this was the most resistant of all the fungi tested for inhibition by P. aeruginosa and P. cepacia.     

Hyperoxia exaggerates bacterial dissemination and lethality in Pseudomonas aeruginosa pneumonia

Effects of hyperoxia on lethality in mice with Pseudomonas aeruginosa pneumonia were defined, and protective roles of macrolides were examined both in vitro and in vivo. Sub-lethal hyperoxia accelerated lethality of mice with P. aeruginosa pneumonia. Bacterial number was not different in the lungs, but higher in the liver of mice in hyperoxic conditions. Filter-sterilized culture supernatants of bacteria induced loss of viability of alveolar epithelial cells, which was exaggerated in hyperoxia. Metalloprotease blocking by inhibitor or gene-disruption in bacteria resulted in partial reduction of cytotoxic activity in culture supernatants. Co-culture of bacteria with sub-inhibitory concentrations of macrolides, such as azithromycin, reduced cytotoxic activity in the culture supernatants. Azithromycin provided significant survival benefit in hyperoxia–pneumonia model, which was associated with suppression of bacterial dissemination to extra-pulmonary organs. These results suggest that hyperoxia serves as an important cofactor for bacterial dissemination and lethality of P. aeruginosa pneumonia. Our data identify the potential of macrolides to protect individuals with P. aeruginosa pneumonia in the setting of hyperoxia.     

Pseudomonas aeruginosa infection in human immunodeficiency virus infected patients

Objectives: (1) To determine the incidence and outcome of Pseudornonas aeruginosa infection in HIV-infected patients. (2) To study the antimicrobial susceptibility of P aeruginosa isolates in this particular population. (3) To identify risk factors for these infections.Patients and Methods: a retrospective case-control study performed in a 28-bed infectious-diseases unit in a 940-bed university hospital. All cases were defined as HIV-infected patients with severe infections due to P aeruginosa, including bacteriemia, lower or upper respiratory tract infections, infections related to a central venous catheter, and cutaneous/muscular infection. Each case was matched with an HIV-seropositive control not infected by P. aeruginosa and hospitalized on the same dates as the cases.Results: one thousand and thirty-five HIV-infected patients were hospitalized during the study period. A first severe P. aeruginosa infection was documented in 41 patients, giving an overall annual incidence note of 2.51 episodes per 100 admissions. Forty of the 41 case notes were available for analysis. They consisted of 17 cases of bacteraemia, four upper respiratory tract infections, 10 lower respiratory tract infections, three catheter-related infections, and six cutaneous/muscular infections. Of these 40 cases, 60% were nosocomial and the remainder were community-acquired. The overall mortality rate was 22% (47% in bacteraemic forms). Twenty five percent of patients relapsed after an average of 37 days. The case-control comparison showed that AIDS was more frequent among the cases (92% vs. 74%, P = 0.04), who also had a lower PN count (P = 0.005), and a lower CD4 cell count (15.7 ± 18.8/mm³ vs. 115 ± 211/mm³; P = 0.0007). The number of days spent in hospital in the previous 3 months (29.3 ± 20.7 vs. 19.7 ± 14, P = 0.04) was significantly higher among the cases. In a multivariate analysis, examining treatments received in the previous month, only co-trimoxazole [OR = 5.5 (1.1-26.9)], penicillins [OR = 5.2 (1.1-25.3)], steroids [OR = 5.5, (1.2-25.5)] and a CD4 cell count below 50/mm³ [OR = 13.2 (1.4-129.4)] were identified as risk factors.Conclusion: P. aeruginosa infection is a not frequent bacterial disease in highly immunodeficient HIV-infected patients. It is frequently fatal and must be borne in mind in the advanced stages of HIV disease, especially when patients have received co-trimoxazole (trianthoprim-sulphametboxazole), penicillins or steroids.     

In vitro antimicrobial effects of aztreonam, colistin, and the 3-drug combination of aztreonam, ceftazidime and amikacin on metallo-β-lactamase-producing Pseudomonas aeruginosa

Background  

There are limited choice of antimicrobial agents to treat infection with metallo-β-lactamase-producing Pseudomonas aeruginosa. We evaluate the antimicrobial effects of aztreonam alone, colistin alone and the 3-drug combination of aztreonam, ceftazidime and amikacin on 23 strains of metallo-β-lactamase-producing P. aeruginosa by time-killing tests.     

Increased adherence to human epithelial cells of resistant Pseudomonas aeruginosa strains

The adherence of Pseudomonas aeruginosa strains to human epithelial cells from the buccal mucosa, large intestine and urinary tract was studied. Strains resistant to gentamicin and carbenicillin, derived by laboratory training, exhibited enhanced adherence as compared to their sensitive parent strain. The same was found with a strain showing an R-factor acquired resistance to gentamicin. This phenomenon was observed with all epithelial cells tested regardless of their anatomical origin. These results suggest that resistant strains of P. aeruginosa are more likely to colonise mucosal surfaces.     

Epidemiology of Pseudomonas aeruginosa infection in cystic fibrosis and the use of strain genotyping

We describe a study of the epidemiology of Pseudomonas aeruginosa (PA) infection in a group of adults with cystic fibrosis who attended a week-long summer camp in the U.K. Sputum samples were collected from 17 patients at the beginning and at the end of the holiday period. Examination of previous sputum samples had identified 11 patients who were chronically colonised with PA. They shared accommodation during the holiday. The sputum samples from these 11 patients were analysed so as to identify the strains of PA by their genotypic characters. All patients were colonised by unique strains before the beginning of the holiday, with the exception of two pairs of patients whose isolates were indistinguishable. After the holiday, eight of the 11 patients harboured strains of the same genotype as was found in their pre-holiday specimens. In three patients, a strain present post-holiday was different from that found in the pre-holiday specimen. In addition, in the case of one patient, two different genotypes were found in the pre-holiday specimen, only one of which was present after the holiday. Evidence of cross-infection of PA during the holiday was not found. Even so, evidence of person-to-person transmission of PA both within the hospital environment and through social contact is presented and discussed.     

Typing of non-serogroupable Neisseria meningitidis by means of sensitivity to R-type pyocines of Pseudomonas aeruginosa

Thirty-three (66 per cent) of 50 non-serogroupable isolates of Neisseria meningitidis could be typed on the basis of their sensitivities to partially purified rod-type (R-type) pyocines from 13 strains of Pseudomonas aeruginosa. Only seven (11 per cent) of 63 serogroupable meningococci were sensitive to the test pyocines. The pyocine typing method is particularly applicable to the labelling of strains in which autoagglutinability precludes the standard agglutination typing procedure.     

Mortality of COPD Patients Infected with Multi-Resistant Pseudomonas aeruginosa : A Case and Control Study

Abstract Background:   The incidence of infections caused by multiresistant Pseudomonas aeruginosa (MDRP) is increasing, especially in critically ill patients. The relevance of MDRP in the prognosis of chronic obstructive pulmonary disease (COPD) acute exacerbation in patients admitted to the hospital’s general ward is not well known. Patients and Methods:   Case and control study. Cases were patients admitted for COPD acute exacerbation in which a MDRP was isolated from spontaneous sputum. MDRP was defined as the absence of susceptibility to three or more antibiotic families (betalactams, quinolones, carbapenems and aminoglycosides). Patients currently or previously admitted to the intensive care unit (ICU), who had a recent surgery, neoplasia or immunosuppressive treatment were excluded from the study. Patients from the control group were admitted for COPD acute exacerbation and matched 1:1 with each case-patient in terms of age, sex, date of admission and degree of airway obstruction. Pseudomonas aeruginosa susceptible to all antimicrobials or other microorganisms was isolated from sputum. Results:   During the study period (2000–2005), 50 casepatients and 50 controls were included. Crude mortality at 2 years was 60% for the case-patients and 28% for the control group. In the logistic regression analysis adjusted for age, FEV₁ and number of previous hospital admissions, MDRP infection was associated to an increased mortality in comparison to patients without MDRP (OR = 6.2; IC 95%: 1.7–22.1; p < 0.01). Conclusions:   In COPD patients admitted to the general ward, acute exacerbation with MDRP in sputum was associated with higher mortality.     

Pseudomonas aeruginosa in a neonatal intensive care unit: molecular epidemiology and infection control measures

Background  

Pseudomonas aeruginosa, a non-fermentative, gram-negative rod, is responsible for a wide variety of clinical syndromes in NICU patients, including sepsis, pneumonia, meningitis, diarrhea, conjunctivitis and skin infections. An increased number of infections and colonisations by P. aeruginosa has been observed in the neonatal intensive care unit (NICU) of our university hospital between 2005 and 2007.