Xanthomonas maltophilia: an emerging pathogen in patients with HIV disease

Searching for biomarkers of comorbidities in sera of treated HIV-infected patients by isoelectric focusing

Based on their characteristics, we hypothesized that the following parameters, namely collagen IV, glutathione S-transferase, secretory component (SC), and AMP-activated protein kinase α1α2 may be useful serum markers in the detection of comorbidities in treated HIV-infected patients. These parameters were determined in 204 HIV-infected patients and 35 controls by using IEF and densitometry. Collagen IV was undetectable in controls and the majority of HIV-infected patients. Twenty-two HIV-infected patients presented significantly elevated levels of collagen IV, most of them were coinfected with hepatitis C virus and/or hepatitis B virus. SC was undetectable in controls. SC was significantly increased in 81 HIV-infected patients and significantly correlated with aspartate aminotransferase (r = 0.267, p = 0.0049), alkaline phosphatase (r = 0.309, p = 0.0011), and γ-glutamyl-transferase (r = 0.264, p = 0.0054). Glutathione S-transferase levels of HIV-infected patients were significantly higher than the controls (3779 ± 5860 vs. 785 ± 71 DU, p = 0.0007) and significantly correlated with serum urea (r = 0.204, p = 0.0038), triglycerides (r = 0.209, p = 0.0033), and lipase (r = 0.219, p = 0.0025). AMP-activated protein kinase α1α2 levels of HIV-infected patients were significantly higher than the controls (5676 ± 6248 vs. 1189 ± 6248 DU, p = 0.0009). Further studies are needed to demonstrate the relevance of these results to diagnose non-AIDS-related illnesses in HIV-infected patients.

Bacillus subtilis SSE4 produces subtulene A, a new lipopeptide antibiotic possessing an unusual C15 unsaturated beta-amino acid

Subtulene A, a new cyclic lipopeptide, was isolated from the culture broth of Bacillus subtilis SSE4. This antibiotic compound contained the seven common alpha-amino acids, L-Asn-1, D-Tyr-2, D-Asn-3, L-Gln-4, L-Pro-5, D-Asn-6, L-Ser-7 and the unique beta-amino acid-8 present in the iturin family. 1D and 2D NMR, as well as MS analyses, identified the beta-amino acid as 3-amino-13-methyltetradec-8-enoic acid, an Iso C15 long chain beta-amino acid. B. subtilis SSE4 was also found to produce iturin A. B. subtilis SSE4 culture filtrate exhibited both antifungal and antibacterial activities.

Stenotrophomonas maltophilia: the significance and role as a nosocomial pathogen

Stenotrophomonas maltophilia is a significant pathogen that primarily affects patients with co-morbid illnesses, usually malignancies, who have been hospitalized for prolonged periods and received broad-spectrum antibiotic therapy. The organism has been associated with an expanding spectrum of clinical manifestations associated with high case to fatality ratios. Therapy of these infections presents a significant challenge both for the clinician and the microbiologists because of its high-level antibiotic resistance to most of the currently used agents and methodological difficulties in susceptibility testing with this organism.

Isolation of multidrug-resistant Stenotrophomonas maltophilia from cultured yellowtail (Seriola quinqueradiata) from a marine fish farm

Six strains of multidrug-resistant Stenotrophomonas maltophilia were isolated from cultured yellowtail. The strains were divided into two clusters based on the 16S rRNA genes, and all of them contained L1 metallo-beta-lactamase and L2 beta-lactamase genes. Differences in the intercluster divergence between the lactamase genes suggest that horizontal transfer of the genes occurred.

Attributable mortality of Stenotrophomonas maltophilia bacteremia

A systematic evaluation of the attributable mortality of Stenotrophomonas maltophilia bacteremia was undertaken in a matched, retrospective, case-control study. We determined the attributable mortality rate (26.7%) and mortality risk ratio (an 8-fold increase) of S. maltophilia bacteremia. The attributable mortality rate for S. maltophilia bacteremia is similar to the attributable mortality rate for other nosocomial bloodstream infections.

Enterobacter spp. infections complicating the course of HIV disease

Through a retrospective review of clinical and laboratory data of 2517 consecutive patients with HIV disease hospitalized since 1991, 13 patients were identified (0.52%), who suffered from a confirmed Enterobacter spp. infection (urinary tract disease in 7 cases, sepsis in 4 patients, and pneumonia in 2 cases). A severe immunodeficiency was recognized in all cases, as expressed by a mean CD4+ lymphocyte count <60 cells/microL, and frequently, a prior diagnosis of AIDS. Bloodstream infection proved linked to a lower mean CD4+ cell count, a more frequent occurrence of leukopenia-neutropenia, and nosocomial origin of the infecting pathogen. Hospital-acquired Enterobacter spp. disease was more frequent than community-acquired, and was significantly associated with leukopenia-neutropenia, and a diagnosis of AIDS. Antibiotic susceptibility assays showed a resistance rate to ampicillin and cephalothin involving >90% of tested strains, and a higher (but varied) sensitivity to other beta-lactams, aminoglycosides, fluoroquinolones, and cotrimoxazole. Adequate chemotherapy provided clinical and bacteriological success in all evaluated patients, in the absence of mortality or relapses. Only 34 episodes of HIV-associated Enterobacter spp. infection have been reported to date in 11 different literature studies. Our data point out that also Enterobacter spp. organisms may have an appreciable pathogenic potential in patients with HIV disease, especially in those with a low CD4+ lymphocyte count, leukopenia-neutropenia, who are hospitalized. Despite the unpredictable antibiotic susceptibility profile of these organisms, HIV-related Enterobacter spp. disease may be properly managed through rapid identification and timely and appropriate antimicrobial treatment.

Acinetobacter infections in patients with human immunodeficiency virus infection: microbiological and clinical epidemiology

BACKGROUND

We evaluated the role of complications caused by Acinetobacter spp. in the setting of HIV infection.

METHODS

Clinical records of 1,923 consecutive HIV-infected patients hospitalized in a 9-year period were retrospectively reviewed, in order to identify all cases of Acinetobacter spp. complications, and to assess their occurrence and outcome according to several epidemiological, clinical and laboratory parameters.

RESULTS

Ten patients out of 1,923 (0.52%) developed Acinetobacter spp. infections: sepsis in four cases, urinary tract infection in three, pneumonia in two and septicaemic pneumonia in the remaining patient. All patients were severely immunocompromised, as shown by a mean CD4+ lymphocyte count of 122 cells/microl and a frequent prior diagnosis of AIDS. As opposed to other infections, septicaemia was associated with a significantly lower CD4+ cell count and a more frequent occurrence of neutropenia. Hospital-acquired Acinetobacter spp. infections were significantly more frequent than community-acquired ones, and prevailingly involved patients with AIDS and leucopenia, being responsible for frequent blood dissemination. Antimicrobial, corticosteroid and cotrimoxazole treatment were frequently carried out during the month preceding disease onset. Antibiotic susceptibility studies proved the complete resistance of microbial isolates to ampicillin and cephalothin and poor sensitivity to second-generation cephalosporins and gentamicin, while greater susceptibility was shown to ceftazidime, netilmicin and amikacin, followed by piperacillin, cotrimoxazole and quinolones. Appropriate antimicrobial treatment led to clinical and microbiological cure in all cases, with no related mortality or relapses.

CONCLUSIONS

Since only 23 episodes of HIV-associated Acinetobacter spp. infections have been described to date in 11 different reports (nine cases of bacteraemia, eight of pneumonia, two of urinary tract involvement, one of intravenous access device infection, one of meningitis and two with unspecified localization), our series represents the largest one dealing with HIV-associated Acinetobacter spp. infections. According to our experience, Acinetobacter spp. may be responsible for appreciable morbidity among patients with HIV infection, above all when a low CD4+ cell count, neutropenia and hospitalization are present. Clinicians and microbiologists who work in the field of HIV infection should consider the potential pathogenic role of Acinetobacter spp. organisms even in the absence of some presumed risk factors, because of the relationship between these infections and immunodeficiency, hospitalization, other infectious complications, prior antibiotic and steroid treatment and extended antimicrobial resistance patterns.

Pseudomonas spp. complications in patients with HIV disease: an eight-year clinical and microbiological survey

Two hundred and twenty-four episodes of Pseudomonas spp. complications that occurred in 179 consecutive patients with HIV infection were retrospectively reviewed. Pseudomonas spp. organisms were responsible for 11.6% of 1933 episodes of non-mycobacterial bacterial diseases (5.4% of 1072 episodes of sepsis), observed over an 8-year period; 20.7% of patients experienced disease relapses (45 episodes). These complications mostly involved lower airways (66 cases), urinary tract (53 episodes), and blood (34 cases), with Pseudomonas aeruginosa isolated in 161 episodes, and other Pseudomonas spp. in the remaining 63 cases. An advanced HIV disease was frequently present (as expressed by a prior diagnosis of AIDS, a low CD4+ lymphocyte count, and leukopenia-neutropenia). Indwelling intravascular and urinary catheters were often associated with bacteremia and urinary tract involvement, respectively. More than 60% of patients were given antibiotics and/or cotrimoxazole in the month preceding the onset of Pseudomonas spp. disease. Bacterial strains isolated from our HIV-infected patients showed a favorable sensitivity to piperacillin, ceftazidime, imipenem, amikacin, tobramycin, and ciprofloxacin. An adequate antimicrobial treatment led to clinical and microbiological cure in 73.2% of patients at the first episode, and in 22.3% more subjects after one or more relapses. A lethal outcome occurred in only eight patients of 179 (4.5%), suffering from a far advanced HIV disease; P. aeruginosa infection directly contributed to death in four cases (sepsis, and/or pneumonia). Nosocomial disease occurred in 46.4% of the 224 episodes, and was significantly related to a previous diagnosis of AIDS, concurrent neutropenia, the occurrence of sepsis or urinary tract infection, disease relapses, the involvement of non-aeruginosa Pseudomonas spp., and a lethal outcome, compared with community-acquired infection. Our experience (the largest reported to date) confirms that Pseudomonas spp. (including non-aeruginosa Pseudomonas spp. organisms) is responsible for remarkable morbidity and mortality among patients with HIV infection, and may pose relevant problems to clinicians and microbiologists involved in the care of HIV-infected patients.

Flavobacterium spp. organisms as opportunistic bacterial pathogens during advanced HIV disease

OBJECTIVE

To assess the role of Flavobacterium spp. infection in patients with HIV disease.

METHODS

Clinical charts of 2412 consecutive HIV-infected patients hospitalized in a 8-year period were retrospectively reviewed, to identify all cases of Flavobacterium spp. infections, and to evaluate their occurrence and outcome according to several epidemiological, clinical, and laboratory parameters.

RESULTS

Six patients out of 2412 (0.25%), developed Flavobacterium spp. complications: septicaemia in five cases, and pneumonia in the remaining patient, with F. meningosepticum and F. odoratum isolated in two cases and one case, respectively, and unnamed Flavobacterium spp. organisms in the remaining three cases. Flavobacterium spp. organisms were responsible for six out of 1939 overall episodes of non-mycobacterial bacterial diseases observed in our patient group (0.31%). All patients were severely immunocompromised, showing a prior diagnosis of AIDS, a mean CD4+ lymphocyte count of 64.2 (range 12-187) cells/microl, and a mean neutrophil count of 1.143 (range 700-1600) cells (range 700-1600) cells/microl. Antibiotic, corticosteriod, or cotrimoxazole treatment was carried out during the month preceding disease onset by three, two and five patients, respectively. Community-acquired and nosocomial Flavobacterium spp. disease were equally frequent, but the latter occurred with a significantly lower mean neutrophil and CD4+ cell count. Antimicrobial susceptibility assays showed complete sensitivity to ciprofloxacin, and variable resistance to ureidopenicillins, ceftazidime, imipenem, aztreonam, and aminoglycosides. An appropriate antimicrobial regimen obtained clinical and microbiological cure in all cases, in absence of related mortality or relapses.

CONCLUSIONS

Since only one episode of HIV-associated F. (Sphingobacterium) multivorum complication has been described to date, our series represents the largest one dealing with Flavobacterium spp. infection in the setting of HIV disease. Our experience suggests that Flavobacterium spp. organisms may play a pathogenic role in patients with advanced HIV disease, even when some commonly recognized risk factors are lacking (i.e. indwelling catheters, instrumentation, IV drug abuse), while a very low CD4+ lymphocyte count, leukopaenia-neutropaenia, and concurrent AIDS-related infectious complications may act as important predisposing factors. In view of the infrequent occurrence of these infections, early suspicion is essential for both clinicians and microbiologists facing immunocompromised patients at risk for invasive bacterial complications. Flavobacterium spp. organisms should be taken into consideration as nosocomial- or community-acquired opportunistic pathogens, due to their relationship with advanced immunodeficiency and their elevated resistance to many antimicrobial agents commonly used against Gram-negative bacterial pathogens.