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Year : 2008  |  Volume : 51  |  Issue : 2  |  Page : 301-303
Investigation of an outbreak of device-related postoperative ventriculitis: A lesson learnt

1 Department of Neuromicrobiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengalur, India
2 Department of Neurosurgery, National Institute of Mental Health and Neurosciences (NIMHANS), Bengalur, India
3 Department of Neuroanaesthesia, National Institute of Mental Health and Neurosciences (NIMHANS), Bengalur, India

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Pseudomonas aeruginosa (P aeruginosa) is one of the most common nosocomial pathogens. We report our experience of a device-related outbreak of postoperative ventriculitis caused by P aeruginosa thus initiating investigation of the unusual occurrence. Five neurosurgical patients were affected, postoperatively. The investigations entailed extensive screening of the common sources of contamination for colonization of P aeruginosa. Sterilized instruments used for surgery, including the ultrasonic aspirator (USA) sets and other hollow devices, were randomly sampled and cultured. Conventional culture methods yielded P aeruginosa, with almost similar antibiotic sensitivity pattern in all the patients and the ultrasonic aspirator, clinching the source of contamination. Routine surveillance, identification of unusual patterns, molecular epidemiological typing would be helpful in quick control of outbreaks of postoperative infections

Keywords: Devices, molecular typing, pseudomonas aeruginosa outbreak, ventriculitis

How to cite this article:
Veena Kumari H B, Nagarathna S, Chandramouli B A, Umamaheshwara Rao G S, Chandramuki A. Investigation of an outbreak of device-related postoperative ventriculitis: A lesson learnt. Indian J Pathol Microbiol 2008;51:301-3

How to cite this URL:
Veena Kumari H B, Nagarathna S, Chandramouli B A, Umamaheshwara Rao G S, Chandramuki A. Investigation of an outbreak of device-related postoperative ventriculitis: A lesson learnt. Indian J Pathol Microbiol [serial online] 2008 [cited 2020 Feb 18];51:301-3. Available from: http://www.ijpmonline.org/text.asp?2008/51/2/301/41697

   Introduction Top
 Pseudomonas aeruginosa Scientific Name Search . aeruginosa) is one of the common virulent nosocomial pathogens that cause significant morbidity and mortality. As per the National Nosocomial Infection Surveillance System (NNIS) report, P. aeruginosa ranks among the top five most frequently encountered bacteria responsible for health care-associated infections. [1] Several P. aeruginosa outbreaks have been linked to medical devices. [2] Although P. aeruginosa has been reported as a causative organism for postoperative meningitis after neurosurgery, it is infrequently reported as a cause of ventriculitis. [3]

We report our experience with a device-related outbreak of ventriculitis caused by P. aeruginosa . We also describe the procedures employed to identify the source of infection and the preventive measures undertaken to resolve the problem.

   Materials And Methods Top

There was an unusual, sudden, consecutive increase in the occurrence of postoperative ventriculitis, caused by the same organism, over a 3-month period (November 2003-January 2004). Laboratory-based ward liaison surveillance facilitated the detection of the increased incidence of these infections.

Five consecutive patients who underwent neurosurgical operations were affected postoperatively. Lumbar and ventric cerebrospinal fluid (CSF) samples from each of the five patients were received at the laboratory. Both samples of three of the patients showed pleocytosis and plenty of pus cells and gram-negative rods on grams staining with culture positivity. In one of the patients, the lumbar puncture (LP) cerebrospinal fluid (CSF) cell count and grams staining were suggestive of infection but culture was sterile, probably due to low load of the organism in the LP CSF or nonviability due to antibiotics to be recovered in culture; but ventricular CSF of the same patient was culture positive. LP CSF of another patient had no microscopic features or culture suggestive of infection, but the ventric CSF had pleocytosis with culture positive for P. aeruginosa .

An investigation of the above episode for the source of infection became necessary and consisted of environmental sampling, including common-use soaps, hand lotions, sinks, taps, equipments, air, water, staff sampling and sampling of the operating room (OR), which indicated no clue to the outbreak. Infection control measures, including environmental cleaning and disinfection, were reinforced but to no avail. The recurrent isolation of P. aeruginosa in the CSF specimens eventually led us to investigate the probable contaminated materials used during surgery.

Therefore, suspicion was also focused on the sterilized instruments used for surgery, including the ultrasonic aspirator (USA) sets and other hollow devices; the instruments were randomly sampled and cultured [Figure 1]. The aspirator sets were considered to be a potential source of contamination as they have fine channels that are used for irrigation of saline and channels for aspiration of the tumor; extreme care is required to decontaminate and dry these channels before sterilization. In our institution, these sets were being sterilized using formaldehyde tablets. Sampling of the sterilized sets was carried out by flushing the irrigation and aspiration channels with sterile normal saline. In addition to the above samples, aspirate from the surgical aspirator set used on one patient who eventually developed ventriculitis on the third postoperative day also was sampled. All the samples were subjected to bacteriological culture.

Conventional culture method, by inoculating the sample into thioglycollate broth and plating on to chocolate agar and Mac Conkey agar, was carried out to isolate the organisms.

   Results Top

The age of the affected patients ranged from 6 to 45 years. All were male patients. The primary diagnosis of these patients was medulloblastoma.

Nonlactose fermenting colonies with green pigment production and oxidase positive reaction were noted in all the isolates. They were identified as P. aeruginosa in all the cases except LP CSF of two patients, which remained sterile on culture, but ventric CSF of the same patients was culture positive. The strain was sensitive to ciprofloxacin, ofloxacin, amikacin, cefotaxime, ceftazidime, ceftriaxone, piperacillin and gentamicin in all the samples. The microbiological culture of the postoperative suction material from the aforementioned patient also yielded P. aeruginosa . The antibiotic sensitivity pattern of this organism was similar to that of the organisms cultured from the postoperative CSF samples of the same patient on two successive occasions and also the samples drawn from the sterile USA before it was used during the surgery. This organism was also similar to the P. aeruginosa isolated from the postoperative CSF samples of the other four patients. Repeat isolates in all patients also yielded P. aeruginosa with more or less similar antibiotic sensitivity. The fact that the organism isolated from suction material of one of the USA sets was similar to that isolated from all the patient samples pinpoints the USA set as being the culprit source of infection.

Following the above episode, the practice of formaldehyde sterilization of the surgical aspirators was changed to ethylene oxide (ETO) sterilization. The cultures of all the sets remained sterile thereafter.

All the patients had antimicrobial therapy as per the sensitivity pattern of the isolate. Successful eradication of P. aeruginosa was verified by post-treatment culture-negative CSF specimens in four patients. Out of these, one patient had intermittent CSF culture positivity and eventually responded to the treatment. Only one patient in this series died. This patient had other comorbidities, in addition to ventriculitis, which could have contributed to the mortality. The postoperative hospital stay of the affected patients ranged from 6 to 20 days. On follow-up, the surviving patients had no recurrence of ventriculitis.

   Discussion Top

Outbreaks of postoperative infections caused by surgical instruments such as laparoscopes, [4] biopsy forceps, [5] surgical drills [6] have been reported earlier. Inadvertent errors in the procedures used for sterilization of the instruments form the basis of these outbreaks. Prompt identification of the source of infection and modification of the sterilization procedures resulted in rapid containment of the damage.

Instrument-related infections are rarely reported in neurosurgical practice. In the present investigation of the outbreak, although the results of preliminary screening were negative, constant surveillance of the patients strengthened our impression of a possible source related to surgical procedures. The potential device-related avenues of contamination considered were 1. infected instruments reused without adequate cleaning and sterilization, i.e., procedural breaches in reprocessing protocols; 2. nonadherence to recommended guidelines for disinfection; 3. existence of the organisms in areas that are inaccessible for cleaning and disinfection; 4. presence of stubborn organisms resistant to disinfection; and 5. contaminated water, which would allow the organisms to lurk inside the instrument. After a detailed investigation, the source of infection was traced to one of the USA sets sterilized by formaldehyde tablets.

Procedural deficiency and failure to mechanically clean the equipment causing several episodes of contamination has been reported. [7] Another earlier report also documented the control of P. aeruginosa outbreak by eradicating a contaminated hydrotherapy equipment. [8] Outbreaks of nosocomial infections caused by P. aeruginosa from different sources, including contaminated respiratory, endoscopic, urodynamic and pressure-monitoring equipments, have been documented. [9] A concerted effort is required to eliminate the infection when such episodes are identified. In our case, a coordinated effort by the staff in extensive cleaning of the USA sets and education of the medical staff and health care workers regarding transmission of infection from patient to patient through hands or contaminated materials were the measures undertaken to control the further spread of the infection, in addition to changing the technique of sterilization of USA sets.

In the present episode, after recognizing the ineffectiveness of formaldehyde sterilization, the USA sets were subjected to ethylene oxide (ETO) sterilization. The outbreak could be successfully controlled with this change in the practice of sterilization. The cultures from the ETO-treated sets remained sterile thereafter. Periodic surveillance of cultures of the aspirator sets and other possible sources is currently being carried out to forestall any further outbreaks.

The epidemiology of P. aeruginosa has been studied by the analysis of phenotypic markers, including antimicrobial sensitivity profiles. However, genotyping methods such as pulsed-field gel electrophoresis (PFGE) are more useful tools to characterize the identity of bacterial strains like P. aeruginosa . [10] Unfortunately, we were unable to perform a genotype study, which would have enabled us to establish the genetic relatedness of the isolates involved in this outbreak.

   Conclusions Top

In the present report, we have described an outbreak of postoperative ventriculitis, the source for which was traced to the USA used during surgery. The event led to a change in the practices of sterilization of this equipment. This experience underlines the need for assiduous implementation of correct reprocessing protocols, adherence to guidelines and closer collaboration between infection control practitioners, user personnel and instrument manufacturers. With increasing use of complex neurosurgical devices, there is great potential for infections unless measures are implemented to assure total sterility during the procedures. Such situation demands vigilance on the part of microbiological laboratories to routinely review pathogen isolates, identify unexpected clusters of infection, formalize monitoring of the isolate patterns and isolate surveillance to detect trends early and avoid unnecessary transmission of infection.

Also, the surveillance programs for infections in hospitals should constitute molecular typing of microorganisms involved in the outbreaks, enabling speedy reporting of the pathogens before being struck by outbreaks causing major damage. Molecular investigations of the outbreaks would be of utmost use to establish a comparative and correlative epidemiological trend of the outbreak.

Finally, we would suggest that we learn from mistakes and ask ourselves why lessons from published reports of outbreak are apparently not being learned.

   References Top

1.Ortolano GA, Angelbeck JH, Cervia IS, Canonica FP. Waterborne Pseudomonas aeruginosa: A controllable source of hospital care-associated infection. Am J Infect Control 2004;32:470-8.  Back to cited text no. 1    
2.Vianelli N, et al. Resolution of Pseudomonas aeruginosa outbreak in a haematology unit with the use of disposable sterile water filters. Haematologica 2006;91:983-5.  Back to cited text no. 2  [PUBMED]  [FULLTEXT]
3.Trick WE, Kioski CM, Howard KM, Cage GD, Tokars JI, Yen M, et al. Outbreak of Pseudomonas aeruginosa ventriculitis among patients in a neurosurgical intensive care unit. Hospital Infections Program, Centers for Disease Control and Prevention, Atlanta, Georgia, 30333, USA. Infect Control Hosp Epidemiol 2000;2:204-8.  Back to cited text no. 3    
4.Vijayaraghavan R, Chandrashekhar R, Sujatha Y, Belagavi CS. Hospital outbreak of atypical mycobacterial infection of port sites after laparoscopic surgery. J Hosp Infect 2006;64:344-7.  Back to cited text no. 4  [PUBMED]  [FULLTEXT]
5.Corne P, Godreuil S, Jean-Pierre H, Jonquet O, Campos J, Jumas-Bilak E, et al. Unusual implication of biopsy forceps in outbreaks of Pseudomonas aeruginosa infections and pseudo-infections related to bronchoscopy. J Hosp Infect 2005;61:20-6.  Back to cited text no. 5  [PUBMED]  [FULLTEXT]
6.Rutala WA, Weber DJ, Thomann CA. Outbreak of wound infections following outpatient podiatric surgery due to contaminated bone drills. Foot Ankle 1987;7:350-4.  Back to cited text no. 6  [PUBMED]  
7.Daniel AC, Steven MG, Atul CM. Infection control in the bronchoscopy suite: A review of outbreaks and guidelines for prevention. Am J Respir Crit Care Med 2003;167:1050-6.  Back to cited text no. 7    
8.Richard P, Le Flock R, Chamoux C, Pannier M, Espaze E, Richet H. Pseudomonas aeruginosa outbreak in a burns unit: Role of antimicrobials in the emergence of multiply resistant strains. J Infect Dis 1994;170:377-83.  Back to cited text no. 8    
9.Moolenaar RL, Crutcher JM, San Joaquin VH, Sewell LV, Hutwagner LC, Carson LA, et al. A Prolonged outbreak of Pseudomonas aeruginosa in a neonatal intensive care unit: Did staff fingernails play a role in disease transmission? Infect Control Hosp Epidemiol 2000;21:80-5.  Back to cited text no. 9  [PUBMED]  [FULLTEXT]
10.Gales AC, Torres PL, Vilarinho DS, Melo RS, Silva CF, Cereda RF. Carbapenem-resistant Pseudomonas aeruginosa outbreak in an ICU of a teaching hospital. Braz J Infect Dis 2004;8: 267-71  Back to cited text no. 10  [PUBMED]  [FULLTEXT]

Correspondence Address:
A Chandramuki
Department of Neuromicrobiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore - 560 029, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.41697

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