Bacterial Infections Caused by Achromobacter xylosoxidans

Mohammed Kadum Al-Araji,Samah Ali
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Keywords : Achromobacter xylosoxidans, infections.
Medical Journal of Babylon  10:1 , 2014 doi:1812-156X-10-1
Published :2013

Abstract

Achromobacter xylosoxidans was first time isolated in Iraq from patients admitted to Medical city in Baghdad from july 2010 to july 2011 whose majority were compromised, Eleveenth patients were infected by this microorganism in different body sites and frequently isolated in combination with other organisms and finding in all well-described cases in which its pathogenic role is clearly demonstrated and may be confused with Pseudomonas species in laboratory diagnosis.The laboratory characteristics were done by culturing in different media and by biochemical reactions and showed a differents in their characteristics from Pseudomonas species.

Introduction

Achromobacter xylosoxidans is Gram-negative rod aerobic, motile, oxidase-positive and catalase-positive, its oxidizes xylose and glucose[1]. This organism causes apportunistic infection in patients who are compromised and usually are exists in water environment and may be confused with Pseudomonas in their similarities in some biochemical reactions .This microorganism is rarely isolated from clinical material and was initially characterized by Holmes et al [2] and further studied and named byYabuuchi and Ohyama [3]. Achromobacter is frequently isolated in nosocomial infections and is especially prevalent in intensive care units, where both sporadic cases as well as epidemic and endemic occurrence is common. A. baumannii is a frequent cause of nosocomial pneumonia,especially of late-onset ventilator associated pneumonia. It can cause various other infections including skin and wound infections, bacteremia, and meningitis, The purpose of this study that A.xylosoxidans is firstly isolated in Iraq (Baghdad city) causes severe acute infections in both compromised and non compromised patients and isolated from different body sites. In November, 2004, the CDC reported an increasing number of A. baumannii bloodstream infections in patients at military medical facilities in which service members injured in the Iraq/Kuwait region during Operation Iraqi Freedom (OIF) and in Afghanistan during Operation Enduring Freedom (OEF) were treated. (1)Most of these were multidrug-resistant. Among one set of isolates from Walter Reed Army Medical Center, 13 (35%) were susceptible to imipenem only, and two (4%) were resistant to all drugs tested. One antimicrobial agent, colistin (polymyxin E), has been used to treat infections with multidrug-resistant A. baumannii; however, antimicrobial susceptibility testing for colistin was not performed on isolates described in this report. Because A. baumannii can survive on dry surfaces for up to 20 days, they pose a high risk of spread and contamination in hospitals, potentially putting immune-compromised and other patients at risk for drug-resistant infections that are often fatal and, in general, expensive to treat.

Materials and methods

Patients:
Eleventh patients were admitted to Medical city hospitals in Baghdad from july 2010 to july 2011 complained from different diseases with different ages and sexes as shown in table (1). Most of the patients were greater than 50 years of age and had an underlying illness at the time that A. xylosoxidans was isolated. The organism was considered the primary pathogen in most patients requiring therapy. The characteristic of A.xylosoxidans are listed in Table (2).


Isolation and Identification of Bacteria :
All specimens were examined microscopically and plated on several agar media, including MacConkey agar and Blood agar, plates, and incubated under , aerobic and anaerobic at 37°C for 24 up to 72 h.The colonies were identified by direct Gram stain and all biochemical tests were done by API-20 system (bioMérieux) to confirm the identification of A. xylosoxidans isolates, and other biochemical tests and fermentation of carbohydrates reaction
see table (2).


Antimicrobial susceptibility test:
Considering one isolate per patient, and considering that each isolate showed the same antimicrobial profile during the whole study period, To assess the sensitivity to piperacillin, piperacillin–tazobactam, cefotaxime, cefepime, ceftazidime, ciprofloxacin, levofloxacin, chloramphenicol, imipenem,, trimethoprim–sulfamethoxazole, gentamicin, rifampin, and tetracycline, an agar diffusion method (Kirby–Bauer) and MIC technique were used see table (3). A. xylosoxidans isolates were included for the antimicrobial susceptibility analysis. These isolates were obtained from several clinical samples, i.e., sputum, blood, vascular catheter, burn wound, and urine.


Interpretative criteria for susceptibility for all of the methods used in the study were in accordance with Clinical and Laboratory Standards Institute (CLSI) criteria(4)



Results

especially of late-onset ventilator associated pneumonia. It can cause various other infections including skin and wound infections, bacteremia, and meningitis, The purpose of this study that A.xylosoxidans is firstly isolated in Iraq (Baghdad city) causes severe acute infections in both compromised and non compromised patients and isolated from different body sites. In November, 2004, the CDC reported an increasing number of A. baumannii bloodstream infections in patients at military medical facilities in which service members injured in the Iraq/Kuwait region during Operation Iraqi Freedom (OIF) and in Afghanistan during Operation Enduring Freedom (OEF) were treated. (1)Most of these were multidrug-resistant. Among one set of isolates from Walter Reed Army Medical Center, 13 (35%) were susceptible to imipenem only, and two (4%) were resistant to all drugs tested. One antimicrobial agent, colistin (polymyxin E), has been used to treat infections with multidrug-resistant A. baumannii; however, antimicrobial susceptibility testing for colistin was not performed on isolates described in this report. Because A. baumannii can survive on dry surfaces for up to 20 days, they pose a high risk of spread and contamination in hospitals, potentially putting immune-compromised and other patients at risk for drug-resistant infections that are often fatal and, in general, expensive to treat. oxidase, and catalase positive.Glucose was oxidized slowly as was xylose, whereas other carbohydrates were not. Tests for urease, lysine decarboxylase and arginine dihydrolyase were negative. A. xylosoxidans isolates were multidrug-resistant, showing resistance to tocephalosporins, including cefepime (MIC > 16 ?g/mL), ceftazidime (MIC > 16 ?g/mL), and cefotaxime (MIC > 32 ?g/mL), to carbapenem (imipenem MIC > 8 ?g/mL; meropenem MIC > 8 ?g/mL), to aminoglycosides (gentamicin MIC > 8 ?g/mL), to ciprofloxacin (MIC > 2 ?g/mL), to, and trimethoprim–sulfamethoxazole (MIC > 2/38 ?g/mL). On the other hand, these ten isolates were sensitive to piperacillin (MIC < 4 ?g/mL) and piperacillin–tazobactam (MIC < 4/4 ?g/mL). All six chronically infected patients carried multidrug-resistant isolates, and chloramphenicol (MIC < 16 ?g/mL). Also, these isolates were sensitive to piperacillin and piperacillin–tazobactam. Table (3) summarized the antibiotic susceptibilities of our six isolates as determined by the standard disk diffusion method. Most isolates were sensitive to carbencillin and Trimethoprim/sulfamethoxazole. A. xylosoxidans infected patients (case group) were compared with those of chronically P. aeruginosa infected patients (control group); thus, two groups were matched for age, gender, body weight, FEV1, and P. aeruginosa infection status. A. xylosoxidans had never been isolated from any patient of the control group. Nutritional status was calculated as the body mass index (BMI, kg/m2). We found no significant differences in the forced expiratory volume in 1 s (FEV1) and body mass index (BMI) (11), when comparing the case group of A. xylosoxidans chronically infected patients with the control group of P. aeruginosa chronically infected patient.

Discussions

The clinical impact of A. xylosoxidans infection is not clear, as well as its lung colonization. Our data are not indicative of increased morbidity linked to this infection/colonization. Besides, our study design does not indicate effects on the clinical status from chronic/intermittent/sporadic A. xylosoxidans infection. We found no significant difference in the FEV1 and BMI comparing chronically A. xylosoxidans infected patients with chronically P. aeruginosa infected patients during the study period. The mild lower mean FEV1 observed in patients with chronic A. xylosoxidans infection could also have been influenced by other covariates, such as diabetes. All chronically A. xylosoxidans infected patients were co-colonized also by P. aeruginosa and, generally, 43.3% of patients present also P. aeruginosa infection. In the study of Van Daele et al. (12), there is indicated the strong tendency by A. xylosoxidans to install itself in a lung already infected by P. aeruginosa. But, in this study, only patients colonized by P. aeruginosa were enrolled. Our data also indicate this tendency by A. xylosoxidans but, differently from the study of Van Daele et al., our population also included patients not co-colonized by P. aeruginosa. Thus, we can affirm that A. xylosoxidans can infect a lung also not previously colonized by P. aeruginosa. As a consequence of the increasing use of antibiotics concomitant to acute pulmonary exacerbations in pneumonia patients due to Streptococcus pneumonia infection, A. xylosoxidans as well as other non-fermentative Gram-negative bacteria are showing growing drug resistance. Our data support this evidence because of frequent previous colonization with P. aeruginosa. It is well known that, for most of the non-lactose fermenting, Gram-negative rods, the disk diffusion antibiogram is not validated by the CLSI. In fact, there are several interpretation problems, such as unclear inhibition zone borders. Consequently, in the present study, a microbroth dilution assay was also carried out and no differences were found between the two methods. In 1971, Yabuuchi and Ohyama described a nonfermentive, gram-negative, peritrichous rod that they isolated from purulent ear discharges of seven patients with chronic otitis media and proposed the name Achromobacter xylosoxidans [3]. The minimal characteristics for the identifications of A.xylosoxidans are as follows; motile, gram-negative, asporogenous, straight rods with peritrichous flagella, positive reaction for oxidase, catalase and Simmons citrate, oxidation of xylose and glucose but not of maltose and other carbohydrates , and negative tests for urease, lysine decarboxylase and arginine dehydrolylase . Table (4). observed that the A.xylosoxidans can be differentiated Pseudomonas spp. In their biochemical reactions. The antibiotic sensitivity pattern, although indistinguishable from that of some pseudomonads is considered fairly typical. Most of our strains see Table (3) were resistant to the currently used aminoglycosides but were sensitive to polymyxin B and Trimethaprime/ sulfamethaxazole. All of our strains were sensitive to carbenicillin, but were resistant to other semisynthetic penicillins.Some strains were sensitive to chloramphenicol, tetracycline and colistin. Clinically A.xylosoxidans has been isolated from many types of specimens, most frequently from the urine,blood,respiratory tract, spinal fluid and ears see Table (4). Unfortuntely sufficient clinical information is missing from most descriptions. Thus it is difficult to assess the clinical significance of its isolation. The fact that A.xylosoxidans is frequently isolated in combination with other organisms makes it even more difficult to determine its pathogenic role. However, there are a few well-described cases in which its pathogenic role is clearly demonstrated. The source of A.xylosoxidans and its natural habitat are unknown;two of their strains were isolated from a swimming pool and from a chlorhexidine solution.In conclusion A.xylosoxidans causes apportunistic infections in patients with underlying illness. The organism probably exists in a water enviroment and can be confused with pseudomonas species. The organsim is usually sensitive to carbenicillin, commonly sensitive to chloramphenicol, tetracycline and trimethaprime/ sulfamethaxazole and resistant to other penicillins and currently used aminoglycosides. In conclusion, the results of the present study can represent a further step toward the understanding of the epidemiology of these microorganisms and of a possible correlation between the microbiological data and clinical outcomes of A.xyloxidans infected patients. Appropriate antimicrobial treatment led to clinical and microbiological cure in all cases, with no related mortality or relapses.

Conclusions

N/A

References

1-Centers for Disease Control and Prevention (CDC) (2004). "Acinetobacter baumannii infections among patients at military medical facilities treating injured U.S. service members, 2002-2004". MMWR Morb Mortal Wkly Rep 53 (45): 1063–6.

2-Holmes,B.; J.J.S.Snell and S.P.Lapage. (1977). Strains of Achromobacter xylosoxidans from clinical material J.Clin.Pathol 30:595-601

3-Yabuuchi,E. and A.,Ohyama . (1971). Achromobacter xylosoxidans,n,sp. From human ear discharge Jpn.J.Microbiol 15:471-481.

4-National Committee for Clinical Laboratory Standards (NCCLS).(2002). Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically, 5th edn. Approved Standard M7-A5. NCCLS, Wayne, PA.


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