Rapid identification of Nocardia cyriacigeorgica from a brain abscess patient using MALDI-TOF-MS.

Nocardia cyriacigeorgica (N. cyriacigeorgica) is most frequently associated with human infections, including chronic bronchitis, pulmonary disease and brain abscesses. In general, N. cyriacigeorgica causes infections in immunocompromised individuals and has been reported in clinical samples worldwide. However, the isolation and speciation of N. cyriacigeorgica in the routine diagnostic microbiology laboratory are complicated and time consuming. Recent mass spectrometry techniques such as matrix-assisted laser desorption/ionization time-of-flight-mass spectrometry (MALDI-TOF-MS) have been successfully integrated into many routine diagnostic microbiology laboratories, allowing for the rapid, accurate and simple identification and speciation of many different microorganisms, including difficult-to-identify bacterial species. Here, we present a case report of a 65-year-old female patient from the neurology ward of Prince Sultan Military Medical City in Riyadh, Saudi Arabia, who was infected with N. cyriacigeorgica. The bacterium was successfully identified by MALDI-TOF-MS, with species identification subsequently confirmed by sequence analysis of the 16S ribosomal RNA.

Impact of Mycobacterium tuberculosis complex lineages as a determinant of disease phenotypes from an immigrant rich moderate tuberculosis burden country.

BACKGROUND: Growing evidences suggested that the Mycobacterium tuberculosis complex (MTBC) lineages can determine the clinical outcome of pulmonary and extra-pulmonary tuberculosis. However, limited data only available revealing such association of bacterial genotypes and clinical phenotypes from immigrant rich countries. METHODS: A multicenter study has been carried out on a collection of 2092 (1003 extrapulmonary and 1089 pulmonary) MTBC isolates. Genotyping of all the isolates were carried out by spoligotyping and 24 loci based MIRU-VNTR typing. RESULTS: Demographically domination of young Saudi nationals (61.4%) and men (61.2%) were found in this cohort. Lymph nodes (62.4%) and gastrointestinal sites (16.7%) were the most common anatomical sites of infection. The predominant lineages were Delhi/CAS (26.9%), EAI (14.2%) and Ghana (9.9%). Mycobacterium africanum type I and II were reported for the first time in the country among extrapulmonary cases. 'Ancestral' lineages M.bovis (OR-5.22; 95% CI-2.23-8.22, p- < 0.001) and Delhi/CAS (OR-0.57; 95% CI-0.411-0.734, p- < 0.001) were directly associated with lymph node tuberculosis and gastrointestinal tuberculosis (M. bovis-OR-0.33; 95% CI-0.085-0.567, p-0.001 and Delhi/CAS-OR-1.87; 95% CI-1.22-2.53, p- < 0.001) respectively. Among the 'Modern' lineages, EAI showed significant association to central nervous system tuberculosis (OR-1.98; 95% CI-0.76-3.19, p-0.04) and Uganda-I to gastrointestinal tuberculosis (OR-2.41; 95% CI-0.77-4.06, p-0.02). CONCLUSIONS: The findings substantially contribute to the emerging evidences that MTBC lineages influence disease phenotypes and epidemiological consequences.

Mycobacterium riyadhense infections.

Mycobacterium riyadhense is a newly described slowly growing, non-tuberculous mycobacterium species. We describe 2 new cases of Mycobacterium riyadhense infections presenting with extra-pulmonary involvement, and reviewed all previously reported cases in the literature. We also describe the spectrum of the disease and explore treatment options based on the experience with the current and previously reported cases.

Ten-year review of invasive Candida infections in a tertiary care center in Saudi Arabia.

OBJECTIVES: To review the epidemiology of invasive Candida infections in a single center in Saudi Arabia over a subsequent 10-year period. METHODS: This retrospective study was carried out in a single center in Saudi Arabia over a 10-year period. Records of all patients with invasive Candida infections (ICI) over the period from January 2003 to December 2012 were reviewed. Mann-Whitney U test was used for comparison of Candida albicans (C. albicans) versus non-albicans Candida species, and fluconazole resistance versus fluconazole susceptible in relation to crude mortality at 30 days and 90 days. RESULTS: Eight hundred positive sterile site cultures, associated with 652 ICI were identified. Median age was 52 years and 53% of patients were males. Candida albicans were the most common species (38.7%), followed by Candida tropicalis (18.9%), and Candida glabrata (C. glabrata) (16.3%). The proportion of ICI caused by C. albicans remained stable over time (p=0.07), but C. glabrata increased significantly (p<0.001). The median rate of ICI per 1,000 hospital discharges per year was 1.65, with a significant trend towards higher rates over time (p=0.01). Most isolates were susceptible to fluconazole, voriconazole, and amphotericin B. Only 66.7% of Candida krusei were susceptible to caspofungin. Overall 30-day crude mortality was 40.6%. There was no significant difference in crude mortality in association with C. albicans compared with non-albicans species, nor in association with fluconazole resistance. CONCLUSION: The rate of ICI increased significantly in the proportion of ICI caused by C. glabrata. Most isolates remain susceptible to caspofungin, voriconazole, and amphotericin B. The crude mortality remains high.

Persistence of Klebsiella pneumoniae clones with OXA-48 or NDM carbapenemases causing bacteraemias in a Riyadh hospital.

We characterized nine carbapenem-resistant Klebsiella pneumoniae collected over 9 months during 2011 in Riyadh; 8 from Hospital A and 1 from Hospital B. Variable number tandem repeat (VNTR) defined three strains at Hospital A, each with 2 or 3 representatives recovered from separate patients over periods of 6-24 weeks; 2 strains had OXA-48 and 1 had NDM. The single isolate from Hospital B also had OXA-48 but was distinct by VNTR from the Hospital A strains. Two strains with OXA-48 were colistin resistant; the third included a colistin-resistant representative from a colistin-treated patient.

Extended-spectrum and metallo-beta-lactamases among ceftazidime-resistant Pseudomonas aeruginosa in Riyadh, Saudi Arabia.

We investigated the extended-spectrum (ESBLs) and metallo-beta-lactamases (MBLs) among Pseudomonas aeruginosa isolates in Saudi Arabia. Disc susceptibility testing was performed on 200 P. aeruginosa isolates collected during 2010 at the Armed Forces Hospital in Riyadh, with MIC testing and phenotypic screening for ESBLs and MBLs carried out on those found to be ceftazidime resistant. Genes for ESBLs and MBLs were sought by PCR. Thirty-nine (19.5%) P. aeruginosa isolates were ceftazidime resistant, mostly with considerable resistance to other antibiotics except colistin. Twenty-three of these 39 (59%) appeared ESBL positive and 16 (41%) had MBLs. bla(VEB), and bla(GES) genes were found in 20 (86.95%), and 5 (21.74%) of 23 ESBL-positive isolates, respectively whilst bla(VIM) was detected in all 16 MBL-producers. bla(OXA-10-like) often accompanied bla(VEB), bla(VIM) or bla(GES). Several isolates had similar antibiogram and ß-lactamase profiles, and may represent outbreaks; nevertheless, the collection was not dominated by any single clone. This dominance of acquired ceftazidime-inactivating beta-lactamases, often in combination is in contrast to the situation in Europe and the USA, where most ceftazidime resistance in P. aeruginosa is attributable to AmpC and efflux.

Antimicrobial susceptibility pattern of clinical isolates of Pseudomonas aeruginosa.

OBJECTIVE: To determine the level of resistance to the widely used antipseudomonal antibiotics in clinical isolates of Pseudomonas aeruginosa (P. aeruginosa). METHODS: The microbiology database of all clinical isolates of P. aeruginosa at the Armed Forces Hospital, Riyadh, Kingdom of Saudi Arabia, from January 1999 to December 1999 was reviewed. The antimicrobial susceptibilities were determined by a standardized method. RESULTS: Seven hundred and four P. aeruginosa isolates were tested. These strains were commonly isolated from surgical patients followed by intensive care units. Respiratory tract was the most common source of isolation. The antibiotic susceptibility rates were as follows: ciprofloxacin 92.2%, meropenem 91.6%, imipenem 90.2%, amikacin 85.8%, ceftazidime 81.8% piperacillin/tazobactam 81.3% and gentamicin 77.7%. Among 704 strains 6.4% were designated as being multidrug resistant. These were commonly isolated from respiratory tract specimens of patients in intensive care units. CONCLUSION: The clinical significance of these findings is important in the selection of appropriate empiric treatment of serious P. aeruginosa infections. It emphasizes the importance of a conservative approach to antibiotic therapy and continued antimicrobial susceptibility testing surveillance programs to curtail the problem of antibiotic resistance.

Distribution of Candida species among bloodstream isolates.

OBJECTIVE: To identify the distribution of Candida species causing bloodstream infections. METHODS: This study was conducted at the Armed Forces Hospital, Riyadh, Kingdom of Saudi Arabia. All cases of candidemia from the period 1996 through to 2002 were retrospectively identified through the records from the Department of Clinical Microbiology. RESULTS: Two hundred and ninety-four candidemic episodes were identified, 176 (59.9%) occurred in the intensive care units (ICUs), 32 (10.9%) medical, 30 (10.2%) surgical wards, 24 (8%) from patients with hematologic malignancies and 15 (5%) from pediatric wards. Candida albicans (C. albicans) was the most frequently isolated species with 149 (50.7%) cases, followed by Candida tropicalis (C. tropicalis) 61 (20.7%), Candida parapsilosis 32 (10.9%), Candida krusei (C. krusei) 23 (7.8%) and Candida glabrata 21 (7.1%). Other species were not common. There is an increase in the proportion of non C. albicans species as the causative agents of candidemia. In certain clinical settings, non C. albicans species predominate as in the Adult General Intensive Care Unit with C. tropicalis as the most common. While in patients with hematologic malignancies, C. krusei species is the most common. CONCLUSION: These findings reinforce the need for continued and active surveillance programs to address the changes in the species distribution among candidal bloodstream isolates which will help to develop effective, preventive and therapeutic strategies.

Correlation between susceptibility and BRO type enzyme of Moraxella catarrhalis strains.

Clinical isolates of Moraxella catarrhalis (76 isolates) were screened for beta-lactamase production and antibiotic susceptibility. beta-Lactamases (detected in 90.8% of isolates) were typed using isoelectric focusing to BRO-1 (87%) and BRO-2 (13%). Minor variations in electrofocusing patterns between the two types were seen. Isolates expressing BRO type enzymes showed solid resistance to penicillin, ampicillin and cephalothin, in particular BRO-1 producers. BRO-1 isolates were less susceptible to cephems and to beta-lactamase inhibitors than BRO-2 isolates. Isolates harbouring BRO-1 enzymes have more enzymatic activity than those expressed by BRO-2 isolates. Apart from resistance to tetracycline (14.5%), all isolates were consistently susceptible to erythromycin, chloramphenicol, ciprofloxacin and gentamicin. The conjugal transfer of BRO beta-lactamase gene(s) between M. catarrhalis isolates occurred with a frequency of 10(-5) to 10(-7)/donor cell. The data emphasize the importance of M. catarrhalis as an etiological agent spreading beta-lactamases that may inhibit some beta-lactams and lead to failure in treatment of mixed infections.