Antimicrobial resistance among non-fermenting Gram-negative bacteria in Saudi Arabia.

OBJECTIVES: Non-fermentative Gram-negative bacilli (non-fermenters) can cause serious healthcare-associated infections and are often resistant to multiple antibiotics. We examined resistance rates among these bacteria from different regions of Saudi Arabia. METHODS: A cross-sectional study between January and December 2009 examined 8908 clinical non-fermenters from 24 hospitals across Saudi Arabia. Susceptibility testing was monitored to ensure compliance with CLSI guidelines, but the antibiotics tested were at the hospitals' discretion. RESULTS: Out of the 8908 non-fermenters, most were Pseudomonas aeruginosa (72.9%), followed by Acinetobacter baumannii (25.3%) and Stenotrophomonas maltophilia (1.8%). Resistance rates among P. aeruginosa were: polymyxin B, 2.2%; imipenem, 15.9%; ciprofloxacin, 22.0%; amikacin, 22.9%; and gentamicin, 31.2%. Resistance rates among A. baumannii were: imipenem, 5.4%; polymyxin B, 13.2%; ciprofloxacin, 64.0%; trimethoprim/sulfamethoxazole, 73.8%; amikacin, 76.9%; and gentamicin, 77.8%. Resistance rates among S. maltophilia were: polymyxin B, 6.9%; trimethoprim/sulfamethoxazole, 20.5%; and ciprofloxacin, 38.9%. There was major variation in resistance rates between geographical regions. CONCLUSIONS: Resistance rates among non-fermenters were high in Saudi Arabia and were variable among regions.

Nosocomial transmission of community-acquired methicillin-resistant Staphylococcus aureus in a well-infant nursery of a teaching hospital.

BACKGROUND: Infection due to community-acquired strains of methicillin-resistant Staphylococcus aureus (CA-MRSA) has been reported with increasing frequency. Herein is described the nosocomial transmission of CA-MRSA involving 13 neonates and two mothers in a well-infant nursery in a teaching hospital in Saudi Arabia. METHODS: From October to November 2009, temporally related cases of CA-MRSA skin and soft-tissue infection occurred in newborns shortly after discharge from a well-infant nursery. An outbreak investigation including case identification, review of medical records, staff screening, environmental cultures, pulsed-field gel electrophoresis, and a case-control study were conducted. Controls were selected from among asymptomatic neonates admitted to the same nursery and matched for the day of admission. RESULTS: Fifteen subjects were found to be CA-MRSA positive: 13 neonates and two mothers. The crude attack rate among neonates was 5.5% during the outbreak period. All 13 neonates presented with skin and soft-tissue infection; one of the mothers had mastitis and a breast abscess. The source of the outbreak was not evident. Pulsed-field gel electrophoresis showed that all of the tested isolates from one strain except one, all contained the staphylococcal cassette chromosome mec (SCCmec) type IV. CONCLUSION: MRSA strains that initially emerged in the community are now causing disease in health-care settings. Adherence to standard infection control practices, including consistent hand hygiene, in newborn nurseries is important to prevent transmission in such settings.

Treatment of disseminated mycobacterial infection with high-dose IFN-γ in a patient with IL-12Rß1 deficiency.

IFN-γ has been used in the treatment of IL-12Rß1 deficiency patients with disseminated BCG infection (BCGosis), but the optimal dose to reach efficacy is not clear. We used IFN-γ in the treatment of a 2.7-year-old patient with IL-12Rß1 deficiency and refractory BCG-osis. IFNγ was started at a dose of 50 µg/m² 3 times per week. The dose was upgraded to 100 mcg/m² after 3 months, then to 200 mcg/m² 6 months afterwards. Serum mycobactericidal activity and lymphocytes number and function were evaluated throughout the study. There was no clinical response to IFN-γ with 50 or 100 µg/m² doses. However, there was some response to the 200 µg/m² dose with no additional adverse effects. The serum mycobactericidal activity was not significantly different during the whole treatment period. Lymphocytes proliferation in response to PHA was significantly higher after 3 months of using the highest dose as compared to the lowest dose. The tuberculin skin test reaction remained persistently negative. We conclude that in a patient with IL-12Rß1 deficiency, IFN-γ at a dose of 200 µg/m², but not at lower dosages, was found to have a noticeable clinical effect with no additional adverse effects.

Neonatal brucellosis: A case report.

Although brucellosis is not uncommon in Saudi Arabia, neonatal brucellosis has been infrequently reported. In this case of neonatal brucellosis, Brucella abortus was isolated by blood culture from both the mother and the neonate. Serology was positive only in the mother.

A study of bacterial isolates from corneal specimens and their antibiotic resistance profile.

OBJECTIVE: We aim to examine the spectrum of bacteria causing corneal infections and their antibiotic susceptibility patterns. This will serve as a guideline for empiric therapy of corneal infections. METHODS: We conducted the study over a period of 18 months from March 2001 through December 2002 in King Abdul-Aziz University Hospital, Riyadh, Kingdom of Saudi Arabia. Corneal specimens taken from 200 patients were inoculated directly onto different types of media. The isolates were identified and then tested against the appropriate topical or systemic antibiotics. RESULTS: Sixty-seven (33.5%) of the total specimens were culture positive and 133 (66.5%) were culture negative. Fourteen (7%) of these showed organisms in the Gram stained smears and correlated well with the culture reports. Of the 67 positive cultures, 53 (79.1%) were Gram-positive bacteria mostly coagulase-negative Staphylococci 29 (43.3%) followed by Streptococcus pneumoniae (S. pneumoniae) 13 (19.4%). Among Gram-negative bacteria 14 (20.9%), Pseudomonas aeruginosa (P. aeruginosa) 10 (14.9%) was the predominant isolate. All the isolates were sensitive to ofloxacin and the commonly used ocular antibiotics. CONCLUSION: All the isolated bacteria were sensitive to ofloxacin, a fluoroquinolone. Having marked potency for broad-spectrum activity against both Gram-positive and Gram-negative bacteria, make the fluoroquinolones especially the newer generations, a potential single drug therapy for corneal infections.

Comparison of clinico-radiological features of patients with positive cultures of nontuberculous mycobacteria and patients with tuberculosis.

OBJECTIVE: To identify the clinico-radiological features of patients with positive cultures for nontuberculous mycobacteria (NTM) and compare those to a sample of patients with tuberculosis (MTB). METHODS: A laboratory database was used to retrieve all specimens submitted to King Khalid University Hospital, Riyadh, mycobacteriology laboratory for mycobacterial smears and cultures during the period from October 1999-April 2002. Using this database, the original records of the mycobacteriology laboratory and a review of the patient's health records, a standard proforma was completed that included demographic, clinical, radiological and laboratory information on patients included in this study. The patients were divided into 2 groups; the NTM group, which included all patients with positive cultures for NTM and the MTB group, which included a sample of patients with documented tuberculosis. RESULTS: During the study period, 286 patients had positive mycobacterial cultures. Seventy patients (24.5%) grew NTM and 216 (75.5%) grew MTB. For patients with MTB, 54 patients were included as per the selection protocol of the study. There was no difference between the 2 groups in all measured demographic variables. The presence of weight loss and fever was significantly more in the MTB group. Radiologically, the presence of hilar adenopathy was more significant among patients with MTB than those with NTM (17% versus 4%, p=0.02). However, bronchiectatic changes were seen significantly more among NTM patients compared to patients with MTB (26% versus 11%, p=0.03). CONCLUSION: The isolation of NTM in the mycobacteriology laboratory is high. The clinico-radiological features were not sufficiently specific to differentiate patients with NTM from patients with MTB. Local studies are needed to explore NTM disease in various developing countries and identify the NTM species causing infections in non-immunosuppressed patients in each locality.

Bloodstream infections in pediatric patients.

OBJECTIVE: Blood stream infection (BSI) is the leading cause of morbidity and mortality in pediatric patients. This study aims to describe the clinical, microbiological characteristics and outcome of BSI in pediatric patients. METHODS: We collected the clinical data from all pediatric patients with positive blood cultures. We identified all isolates from these patients from January 2004 to December 2004 at King Khalid University Hospital (KKUH), Riyadh, Saudi Arabia, and determined antimicrobial susceptibilities by MicroScan Walk Away 96 (Dade Behring Inc., West Sacramento, CA95691, USA). RESULTS: Two hundred and twenty pediatric patients had BSI, of whom 147 (67%) were males and 71 (32.2%) were from intensive care units (ICUs). Two hundred and ten (95.4%) had single blood culture isolate. One hundred and seventy-three (78.6%) of the isolates were Gram positive bacteria and included the following: Staphylococcus epidermidis (55.4%), Staphylococcus aureus (9.5%) of which 14% were methicillin resistant, Streptococcus pneumoniae (S. pneumoniae) (4.5%), 40% of which were resistant to penicillin and Enterococcus faecalis (4%). Gram negative bacteria were 44 (20%) and included Escherichia coli and Klebsiella pneumoniae (K.pneumoniae) (3.6% each). Three isolates (1.3%) were Candida glabrata. None of the Gram positive isolates were vancomycin resistant. Three K.pneumoniae and one Pseudomonas spp. isolates were multiresistant. One hundred and ninety-four (88%) of BSI isolates were hospital acquired. Fever was the most common presentation of pediatric patients (26%) with positive blood culture with no apparent focus of infection. Respiratory tract infections 26 (12%) were the next most common. We seen sepsis in (7.7%) children between 8 days and 6 months of age. Bone and joint infections, cardiac, renal, gastrointestinal diseases, malignancy and surgical cases were other associated clinical diagnoses of BSI in pediatric patients. Patients with immuno- suppressive disorders with BSI had isolates such as Salmonella spp., S. pneumoniae and Pseudomonas spp. Overall mortality was 13 (6%) (p<0.005) and those patients had underlying serious medical conditions with associated risk factors such as prolonged hospital stay, intensive care unit (ICU) admission, indwelling catheterization, mechanical ventilation and prior antimicrobial use. CONCLUSION: Bloodstream infection is an important cause of morbidity and mortality in pediatric patients. Risk factors for hospital acquired infection include: prematurity, prolonged hospitalization, ICU admission, indwelling catheterization, mechanical ventilation and prior antimicrobial therapy.

Streptococcus pneumoniae serotypes/serogroups causing invasive disease in Riyadh, Saudi Arabia: extent of coverage by pneumococcal vaccines.

BACKGROUND: Serogroup distribution of sterile site pneumococcal isolates varies between developing and developed countries as well as between different geographical regions. The potential efficacy of any pneumococcal vaccine depends on the degree of representation of the prevalent serogroups in the vaccine. We conducted this study to determine the prevalent pneumococcal serogroups causing invasive infections in Riyadh, Saudi Arabia and to estimate the coverage by the various pneumococcal conjugate vaccines. METHODS: S. pneumoniae isolated between February 2000 and November 2001 from sterile sites of patients of all age groups were collected from 8 major hospitals in Riyadh and serogrouped using the latex agglutination method. RESULTS: Isolates from 78 patients, 72% of whom were children, were studied. Eighty-eight percent of the isolates belonged to only 10 serogroups/serotypes, namely 6 and 19, 1 and 15, 14 and 23, 7, 18 and 22, in descending order of frequency. Potential coverage of the 7-valent, 9-valent, and 11-valent conjugate vaccines were 54%, 65% and 73%, respectively. The rate of reduced penicillin susceptibility in the serogroups represented in the 7-valent conjugate vaccine was significantly higher than in the non-vaccine serogroups (62% vs. 25%; P=0.0023). CONCLUSION: The currently available 7-valent pneumococcal conjugate vaccine provides sub-optimal coverage to serogroups causing invasive diseases in our community. However, this vaccine would be a useful adjunct to penicillin prophylaxis in at-risk patients in the community. The effectiveness of the vaccine would be greater if serotype 15 could be included.

Isolation of coryneform bacteria from blood cultures of patients at a University Hospital in Saudi Arabia.

OBJECTIVE: Coryneform bacteria have been increasingly recognized as opportunistic pathogens in recent years. The aim of this study is to identify and determine the antimicrobial susceptibility of coryneform bacteria isolated from blood cultures of patients seen at King Khalid University Hospital (KKUH), Riyadh, Kingdom of Saudi Arabia and review the literature. METHODS: All coryneform bacteria isolated from blood culture specimens between January 2001 and March 2003 were prospectively identified by API Coryne System (BioMerieux, France). Clinical data were collected from each patient's medical record. Antimicrobial susceptibility to 16 antimicrobial agents were determined by minimum inhibitory concentration (MIC) using E-test (AB Biodisk, Solna, Sweden). RESULTS: Out of 50 coryneform bacteria isolated, 19 different species were identified. Corynebacterium propinquum was the most common species 6/50 (12%) followed by Corynebacterium auris 5/50 (10%), Corynebacterium afermentans, Corynebacterium striatum, Dermabacter hominis, Brevibacterium, and Arthrobacter species 4/50 (8%) each. Underlying chest diseases were common among the patients 11/50 (22%), followed by different surgeries 10/50 (20%). Of all, 12/50 (24%) patients were from different intensive care units (ICUs), 36/50 (72%) had either vascular, urinary or respiratory intubation. Three patients in ICUs died, one was an elderly patient with gastrointestinal bleeding and 2 teenagers (one had tracheoesophageal fistula and the other was post-arrest road traffic accident patient). Vancomycin was the most active antimicrobial agent against all coryneform species. The majority had MIC <1 ug/ml. For most isolates, the MIC90s of erythromycin, clindamycin, and ciprofloxacin were above the break points. Corynebacterium striatum was the only isolate susceptible to ampicillin. CONCLUSION: This study revealed that coryneform bacteria are increasingly being recognized as a cause of serious infections in immunocompromised patients. We recommend identification and susceptibility testing of predominant isolates of coryneform bacteria from different clinical sites of seriously ill patients to select the antimicrobial agent necessary for clinical intervention.

Enterococcal bacteremia in a teaching hospital in the Central region of Saudi Arabia.

OBJECTIVE: To study enterococcal blood stream infection including the different species isolated, their antibiotic resistance associated risk factors and outcome of treatment. METHODS: A retrospective and prospective study was carried out over a 12 month period between June 2001 and May 2002 in King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia. Sixty episodes of enterococcal bacteremia with clinical significance detected in adults and neonates were included. Statistical analysis of the epidemiological characteristic, etiologic risk factors and mortality were determined. RESULTS: Fifty-four (90%) of the episodes were hospital acquired. Fifty-five percent of patients were elderly males and 20% were neonates. Patients usually have severe underlying diseases (57%) and the mortality rate was 28%. The estimated duration of hospital stay after acquiring the Enterococcal bacteremia was 40 days. The source of bacteremia remained undetermined in 72% of the episodes. Gastrointestinal tract, urinary tract and intravascular catheter were the most frequently recognized associated sites of infection. Thirty-three patients (55%) had previously received antimicrobial agents (mainly cephalosporins). In this study, intravascular catheter (p=0.0002), urinary catheter (p=0.00001), mechanical ventilation (p=0.002), previous surgery (digestive tract surgery (p=0.01) and prior stay in an intensive care unit (p=0.03) were the factors associated with Enterococcal bacteremia and mortality. CONCLUSION: Efforts to reduce the occurrence of enterococcal bacteremia should be focused on appropriate use of cephalosporins and external devices.

Penicillin resistance in serogroups/serotypes of Streptococcus pneumoniae causing invasive infections in Central Saudi Arabia.

OBJECTIVE: To determine the minimum inhibitory concentrations (MICs) of penicillin, ceftriaxone and vancomycin of serogroups/serotypes of Streptococcus pneumoniae (S. pneumoniae) from invasive diseases in all age groups from major hospitals in Riyadh, Kingdom of Saudi Arabia (KSA). METHODS: All isolates of S. pneumoniae from patients with invasive pneumococcal infections between February 2000 and November 2001 were prospectively collected from 8 major hospitals in Riyadh, KSA. The isolates were confirmed as S. pneumoniae at the King Khalid University Hospitals, Riyadh, KSA and then serogrouped/serotyped using the agglutination method. The MICs for penicillin, ceftriaxone and vancomycin were carried out using the E-test. RESULTS: Forty-three percent of the isolates were resistant to penicillin mostly of the intermediate type (97%). The resistant strains were mainly confined to serogroups/serotypes 6, 23, 19 and 15 and the 7-valent conjugate vaccine covers 76% of the penicillin-resistant strains. Only one isolate was resistant to ceftriaxone. CONCLUSION: In view of the rather insignificant level of highly resistant-penicillin strains and the virtual absence of resistance to ceftriaxone we would like to suggest using ceftriaxone for treating invasive pneumococcal infections outside the central nervous system. We recommend that the conjugate vaccine would be a useful adjunct to penicillin prophylaxis in patients at risk in our community.

Hemophilus influenzae serotype-b meningitis in an adult immunocompetent patient.

We present a case of meningitis caused by Hemophilus influenzae type b in an immunocompetent 41-year-old Saudi lady. The patient was successfully treated with Ceftriaxone for 10 days. A review of Hemophilus influenzae meningitis in adults and the impact of conjugated vaccine on the epidemiology of the disease are given.

Prevalence of H.influenzae biotypes and their clinical significance in a University Hospital.

OBJECTIVE: Hemophilus influenzae is an important pathogen that is responsible for invasive and non-invasive infections in both children and adults. This study aims to assess the relationship of biotypes to the sites of infection, serotypes, antimicrobial susceptibility, beta-lactamase production and age. METHODS: A total of 200 isolates of H.influenzae were obtained from clinical specimens over a period of 12 months from January 2001 through to January 2002 from King Abdul-Aziz University Hospital, Riyadh, Kingdom of Saudi Arabia. RESULTS: Most of the strains were non-typable and were isolated from patients with non-invasive infections. The typable isolates from invasive infections mostly serotype b were isolated from blood, cerebrospinal fluid and hip joint aspirate. Biotype II accounted for 37% of the isolates followed by biotypes III and I (29.5% and 23%). The remaining 10.5% were made up of biotypes IV, V, VI and VII. A significantly high resistance to cotrimoxazole (33.5%) and ampicillin (19%) was observed. Two point five percent of the isolates were resistant to chloramphenicol. All the isolates resistant to ampicillin were beta-lactamase producers and susceptible to cefuroxime, ceftriaxone, ciprofloxacin and rifampicin. CONCLUSION: This study revealed that biotypes II and III are the predominant biotypes of H.influenzae found in non-invasive infections. There is an apparent relationship between biotype and site of infection which could be useful as an epidemiological marker.

Hemophilus influenzae serotype-b meningitis in an adult immunocompetent patient.

We present a case of meningitis caused by Hemophilus influenzae type-b in an immunocompetent 41-year-old Saudi lady. The patient was successfully treated with Ceftriaxone for 10 days. A review of Hemophilus influenzae meningitis in adults and the impact of conjugated vaccine on the epidemiology of the disease are given.

National surveillance of antimicrobial resistance among Gram-positive bacteria in Saudi Arabia.

BACKGROUND: Antimicrobial-resistant Gram-positive bacteria are important causes of serious infections. METHODS: Between January and December 2009, we examined clinical Gram-positive isolates from 24 hospitals across Saudi Arabia. RESULTS: Among the 13750 isolates, Staphylococcus aureus (62.3%) was the commonest, followed by non-group A beta-haemolytic streptococci (14.8%), group A beta-haemolytic streptococci (7.1%), coagulase-negative staphylococci (6.6%), pneumococci (6.0%), and enterococci (3.1%). Resistance rates were high among S. aureus (methicillin-resistant S. aureus: 32%), coagulase-negative staphylococci (oxacillin: 63%) and pneumococci (penicillin G: 33%; erythromycin: 26%; ceftriaxone: 11%); low among enterococci (vancomycin: 1%) and among beta-haemolytic streptococci. Resistance rates varied between regions, but comparison was complicated by differences in antibiotics tested. Many relevant antibiotics were tested against few isolates (e.g. ampicillin, vancomycin, and high-level gentamicin versus enterococci) while unhelpful tests were widely performed (e.g. cefotaxime, ceftriaxone, and imipenem versus staphylococci. CONCLUSION: Resistance is widespread in staphylococci and pneumococci, but not enterococci and beta-haemolytic streptococci in Saudi Arabia. Rationalization of antibiotic panels tested is urgently needed.

Changing epidemiology of tuberculosis detected by an 8-year retrospective laboratory study in a tertiary teaching hospital in central Saudi Arabia.

OBJECTIVE: To study the laboratory diagnosis of tuberculosis (TB), and relate the findings to its epidemiology in Central Saudi Arabia. METHODS: This retrospective study was carried out at the Department of Pathology/Microbiology, King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia between January 2003 and December 2010. Data were retrieved from the hospital information system on laboratory findings. After adjustment, 9,405 specimens were studied. The specimens were stained by Ziehl-Neelsen (ZN), auramine-rhodamine, and cultured in Bactec alert 960, and Lowenstein-Jensen media. Mycobacterium tuberculosis (M. tuberculosis) complex and non-tuberculous mycobacteria were differentiated by ProbTec system and p-nitrobenzoate medium. The BACTEC MGIT 960 SIRE kit was used for susceptibility testing. RESULTS: A total of 568 (6%) specimens grew M. tuberculosis complex, and 87% were from Saudis with an incidence rate of 55.6/100,000 of TB. Time to positive growth in the Bactec liquid medium was directly related to the acid fast bacilli smear load. Most of the positive patients were from the 18-35 years age group. The percentage of multidrug resistance was 0.7%. CONCLUSION: Most patients (87%) were Saudis showing an incident rate of 55.6/100,000. An increase of TB cases was noticed in the 18-35 age group. Resistance to isoniazid was 10.6%, 1% to Rifampicin, 2-8% to Ethambutol, and streptomycin was 6%.

Brucella spp isolated from respiratory sample and grown in Mycobacterium growth indicator tube (MGIT).

Brucellosis remains endemic in many countries including Saudi Arabia. The disinfection of objects and surfaces contaminated with Brucella spp is not difficult, but we encountered a situation in which the organism survived the decontamination and liquefaction procedure adopted for AFB culture. A sputum specimen from a patient was sent for TB culture and the BACTEC MGIT 960 system isolated an organism identified as Brucella spp. The blood cultures and the serological testing had confirmed this case to be brucellosis. Isolation of Brucella spp from sputum samples is rare; this case appears to be the first of its kind. As the clinical presentation of TB may mimic brucellosis and vice versa, we recommend that handling specimens from all cases of undiagnosed PUO should be done with care because of the possibility that it may contain either of these organisms.

Salmonella isolates serotypes and susceptibility to commonly used drugs at a tertiary care hospital in Riyadh, Saudi Arabia.

INTRODUCTION: Resistance of Salmonella to therapeutic agents currently being used for treatment of Salmonella infections is emerging as a global problem. This study aimed to assess the prevalence of Salmonella serotypes and their susceptibility patterns to commonly used drugs for treatment of Salmonella infections including quinolones. Correlation between nalidixic acid susceptibility of these isolates and their ciprofloxacin minimum inhibitory concentrations was also sought. METHODOLOGY: Salmonella isolates (n=213) were collected between January 2007 and May 2009 at King Khalid University Hospital in Riyadh, Saudi Arabia. The isolates were serotyped and their susceptibilities to commonly used first-line anti-Salmonella drugs (ampicillin, ceftriaxone, trimethoprim/sulfamethoxazole, nalidixic acid and ciprofloxacin) were determined using the automated Microscan system, the Kirby-Bauer disk diffusion method, and E-test. RESULTS: The most frequently detected serotype was D1 (37%) followed by the serotypes, B (24%) and C1 (11%). Non-typable Salmonella isolates detected using available conventional Salmonella anti-sera were (11%). Overall resistance rates to nalidixic acid, ampicillin, trimethoprim/sulfamethoxazole and ceftriaxone were 99/213 (46%), 43/213 (20%), 34/213 (16%) and 7/213 (3%), respectively. Of the total isolates, 117 (55%) had a ciprofloxacin MIC of <0.125 µg/ml and among these 105 (90%) were susceptible to nalidixic acid. The remaining 96 (45%) isolates had a ciprofloxacin MIC of ≥ 0.125 µg/ml and among them, 83 (86.5%) were resistant to nalidixic acid. CONCLUSIONS: The majority of Salmonella isolates in this study were non-typhi serotypes. Significantly higher proportions of Salmonellae were resistant to nalidixic acid and ciprofloxacin and a vast majority of nalidixic acid resistant organisms exhibited decreased susceptibility to ciprofloxacin.

Antimicrobial activity of tigecycline against bacterial isolates from intensive care units in a teaching hospital in Central Saudi Arabia.

OBJECTIVE: To test the activity of tigecycline against bacterial isolates including multi-drug resistant (MDR) gram negative and gram positive organisms from intensive care patients. METHODS: Clinically significant gram positive and MDR gram negative isolates from specimens of patients in the intensive care units of King Khalid University Hospital (KKUH), Riyadh, Kingdom of Saudi Arbia between November 1, 2006 and December 31, 2008 were tested against tigecycline by disc diffusion (DD) method. In some isolates, the minimal inhibitory concentration was carried out by E-test method. Some of the gram negative isolates, and gram positive isolates were tested using both methods. The study was approved by the hospital ethics committee. RESULTS: All the 83 gram positive organisms tested by both DD and E-test were susceptible to tigecycline. Two hundred and fifty-four MDR gram negative isolates were tested for susceptibility to tigecycline. Of these 176 tested by DD, 159 (90%) were susceptible, 6 (3.4%) were resistant, and 11 (6.2%) were intermediately susceptible (data are not the same in table 3). From the 188 isolates tested by E-test, 140 (74.4%) were susceptible, 35 (18.6%) were resistant, and 13 (6.9%) showed intermediate susceptibility. For comparison between the methods, 109 isolates of the MDR gram negative organisms were tested by both E test and DD. The difference between the 2 methods was not significant. CONCLUSION: Tigecycline was active against gram positive and most MDR gram negative isolates from patients in medical and surgical intensive cases in KKUH. There was no significant difference between the DD and E-test methods for susceptibility testing of tigecycline against these isolates.

Mycobacterium chelonae complex bacteremia from a post-renal transplant patient: case report and literature review.

In this report we present a case of a young lady with abdominal abscesses and septicemia caused by Mycobacterium chelonae complex. Identification of the organism and initiation of the appropriate antimicrobial therapy was delayed, resulting in significant morbidity and multiple hospital admissions. Gram staining of these organisms from blood culture can be easily overlooked or confused with either debris or diptheroids. We concluded that detection of Gram-positive rod colonies should prompt an acid-fast stain to distinguish diphtheroids from rapidly growing mycobacteria in immunosuppressed patients.