|Year : 2013 | Volume
| Issue : 2 | Page : 135-137
Community acquired methicillin resistant Staphylococcus aureus pneumonia presenting along with multiple subcutaneous abscesses
Simit Kumar, Maitreyi Bandyopadhyay, Mitali Chatterjee, Suranjan Pal, Mallika Ghosh, Parthajit Banerjee
Department of Microbiology, R.G. Kar Medical College and Hospital, Kolkata, India
|Date of Web Publication||10-Sep-2013|
Department of Microbiology, R.G. Kar Medical College and Hospital, Kolkata - 700 037
Source of Support: None, Conflict of Interest: None
Community onset necrotizing pneumonia due to community acquired methicillin resistant Staphylococcus aureus (CA-MRSA) is an emerging clinical entity, especially, following a viral infection, with substantial morbidity and mortality and survivors, have long-term pulmonary complications requiring treatment. The infectious diseases society of America guidelines has recently addressed the issue of MRSA as a possible pathogen that warrants empiric antibiotic therapy for community-acquired pneumonia (CAP) in patients requiring inpatient intensive care unit treatment, recommending the use of vancomycin or linezolid, with linezolid having an advantage due to its documented suppression of panton valentine leukocidin toxin production in CA-MRSA. We report a case of a child presenting with pyothorax and multiple subcutaneous absceses over the deltoid region. The pus from the abscesses and pyothorax and the expectorated sputum showed the growth of MRSA. The case was diagnosed as CA-MRSA pneumonia and was successfully treated with vancomycin but the patient required pulmonary decortications and long-term physiotherapy. The case highlights the importance of considering CA-MRSA in the initial empirical therapy for severe CAP and the long-term morbidity associated with this otherwise fatal disease.
Keywords: Community acquired methicillin resistant Staphylococcus aureus, community acquired pneumonia, necrotizing pneumonia
|How to cite this article:|
Kumar S, Bandyopadhyay M, Chatterjee M, Pal S, Ghosh M, Banerjee P. Community acquired methicillin resistant Staphylococcus aureus pneumonia presenting along with multiple subcutaneous abscesses. Saudi J Health Sci 2013;2:135-7
|How to cite this URL:|
Kumar S, Bandyopadhyay M, Chatterjee M, Pal S, Ghosh M, Banerjee P. Community acquired methicillin resistant Staphylococcus aureus pneumonia presenting along with multiple subcutaneous abscesses. Saudi J Health Sci [serial online] 2013 [cited 2020 Jun 1];2:135-7. Available from: http://www.saudijhealthsci.org/text.asp?2013/2/2/135/117921
| Introduction|| |
Until recently, staphylococcal pneumonia was considered an uncommon community-acquired pneumonia (CAP), accounting for 1-5% of all CAP cases, and occurring primarily in patients with influenza. Recently, however, a new variant of methicillin resistant Staphylococcus aureus (MRSA) has emerged as a pulmonary pathogen. This new variant of S. aureus that causes pneumonia is community acquired (CA-MRSA), containing staphylococcal cassette chromosome mec (SCC mec) type IV as well as the gene encoding panton-valentine leukocidin (PVL), a toxin that destroys poly-morphonuclear leukocytes. CA-MRSA, although primarily a cause of skin and soft-tissue infection, has proved to be a formidable cause of pneumonia.  Diagnosis of CA-MRSA is made in the out-patient setting or by a culture positive for MRSA within 48 h after admission to the hospital with. ,
Community-onset necrotizing pneumonia due to CA-MRSA is an emerging clinical entity, especially following a viral infection, with substantial morbidity and mortality.  Case reports of CA-MRSA pneumonia now span the globe, and the reported cases involve severe necrotizing pneumonia, which often is fatal. ,, The pneumonia often is rapidly progressive; bilateral; and with shock, cavitation of lung parenchyma, and pleural effusion. 
- No medical history of MRSA infection or colonization
- No medical history in the past year of:
- Admission to a nursing home, skilled nursing facility, or hospice
- No permanent indwelling catheters or medical devices that pass through the skin into the body.
Since, suppression of toxin production may correlate with improved outcome, data suggest that vancomycin alone may not be the optimal treatment for pneumonia caused by toxin producing CA-MRSA. Although it has not been established that the combination of a bactericidal agent with a toxin-suppressing agent, such as clindamycin or linezolid, is associated with improved outcome, it is the general impression of experienced clinicians that vancomycin should not be used as a single agent for the treatment of CA-MRSA pneumonia. ,
Although there are a growing number of cases of CAP due to MRSA, the long-term course and recovery of patients have not frequently been reported. ,, The long-term follow-up study by Napolitano et al., has illustrated that the CA-MRSA pneumonia are associated with high morbidity along with long-term complications with prolonged pulmonary symptoms and hypoxemia requiring treatment. 
This study also highlights a significantly worse overall course for patients with mild-to-moderate-severe CAP, who generally had resolution of respiratory symptoms by 14-28 days. This patient had an ongoing supplemental oxygen requirement that lasted 6 months, and he required long-term physiotherapy after hospital discharge.
| Case Report|| |
A 9-year-old male child presented with high-grade fever, respiratory distress for the last 1 week. The patient also had bilateral multiple subcutaneous abscesses over the deltoid region.
On general examination, the patient was grossly wasted, febrile with tachypnea (respiratory rate 44/min) and tachycardia (130/min). On palpation per abdomen, mild tenderness over the epigastrium was noted and the liver was palpable 4 cm below the costal margin. There was no history of immunosuppression, diabetes mellitus, human immunodeficiency virus infection, alcoholism, asplenia, recent hospitalization, instrumentation or having received antimicrobial therapy. He did not have any indwelling catheter or close household contact with anyone with an identified risk-factor, nor was he a worker in a health-care environment. His baseline investigations revealed neutrophilic leukocytosis 10.8 × 10 9 /L, wiith 71% neutrophils, 9% band cells and 7% metamyelocytes. The C reactive protein was raised (>3.2). The chest X-ray done at the time of admission showed right sided pyothorax [Figure 1].
|Figure 1: Chest X-ray showing bilateral lung opacity predominantly on the right side|
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The patient on admission was started empirically on intravenous ceftriaxone and azithromycin and a chest drain was introduced to drain the right sided pyothorax but the patient did not show much improvement to oxygen supplementation. The condition of the patient deteriorated with severe dyspnea manifesting on the 2 nd day of admission and repeat X-ray showed appearance of cystic cavitary lesions. The pus drained from the abscesses over the deltoid region and pleural cavity were collected aseptically and sent for culture and sensitivity. The Gram stain performed from the pus samples showed plenty of pus cells along with gram positive cocci in clusters. After receiving the initial microscopy reports, the patient was started on intravenous vancomycin on day 2, to which the patient responded well, with repeat chest X-ray showing a decreased opacity.
The culture of the pus from the pyothorax and subcutaneous deltoid abscess showed the growth of MRSA, with similar antibiotic sensitivity pattern. The isolates were found to be sensitive to vancomycin, linezolid, clindamycin, trimethoprim/sulfamethoxazole, gentamicin and resistant to penicillin, ampicillin, erythromycin and oxacillin by Kirby-Bauer disc diffusion method. The isolate was confirmed to be methicillin resistant by using cefoxitin 30 μg disc, as per the Clinical Laboratory Standards Institute guidelines.  The blood cultures sent for culture report showed no growth in culture.
After 2 weeks of intravenous vancomycin therapy (15 mg/kg every 12 h), the patient showed complete resolution of the lobar opacity but still had some restricted chest expansion for, which the patient had to undergo lung decortication. The patient was continued on oral linezolid for 2 weeks. Following the decortication the patient had to undergo chest physiotherapy. After 6 weeks of hospital stay the patient was doing well and was finally discharged from the hospital, with some persistent cough. The patient was advised to continue with chest physiotherapy exercises at the time of discharge.
| Discussion|| |
CA-MRSA is predominantly associated with the SCC mec type IV variant of the mec gene which is transported easily on a plasmid or bacteriophage to a susceptible recipient strain, due to its small size. This suggest that the prevalence of methicillin resistance in the community will only increase, potentially even more quickly than it has in the hospital setting.  CA-MRSA pneumonia often resulting in large cavitary lesions, resulting in increased dead space, hypoxemia, and hypercarbia, so transfer to a tertiary care hospital with expertise and equipment for advanced pulmonary support strategies, such as high-frequency oscillatory ventilation, extra-corporeal membrane oxygenation, or other techniques, should be considered early in the course of illness. 
Although knowledge of specific risk-factors for CA-MRSA, such as residence in endemic areas or past antibiotic exposure, is important, However, some patients with CA-MRSA and severe infections have no prior medical comorbidities and no specific MRSA risk factors,  such as in the case of the patient presented here. Therefore, a clinical culture to make a definitive diagnosis of CA-MRSA pneumonia is of paramount importance.
The present report also highlights the importance of considering empiric antibiotic coverage for MRSA infection in patients with severe CAP. The case reported herein had a delay of initiation of empiric antimicrobial therapy for possible MRSA until the 2 nd day of admission. The infectious diseases society of America (IDSA)/American Thoracic Society guidelines  has recommend the following: "For CA-MRSA infection, add vancomycin or linezolid (moderate recommendation; Level III evidence)." Linezolid may have advantages over vancomycin for initial therapy of severe CA-MRSA pneumonia as (1) it has been documented to suppress PVL toxin production in CA-MRSA, , (2) faster bactericidal action, (3) higher penetration into pulmonary tissue, (415% of plasma levels were recovered in epithelial lining fluid), (4) the globally slowly increasing vancomycin minimum inhibitory concentration (MIC)'s ("creep") that result in increased clinical failure despite being susceptible according to defined break points and v) lower nephrotoxicity. This trend has urged the IDSA to issue "Vancomycin therapeutic guidelines" that recommend to aim for trough serum vancomycin concentrations of 15-20 mg/and to maintain trough serum vancomycin concentrations always >10 mg/L to avoid the development of resistance. Further, alternative treatment is recommended for isolates with MIC >2 μg/L, because a targeted area under curve AUC/MIC of 400 is not achievable with conventional dosing (. The ZEPHyR study also, advocates the superiority of linezolid over vancomycin in proven MRSA pneumonia. The problem with recommending drugs like vancomycin and linezolid for the empirical treatment of severe CAP is the fact that it could hasten the development of drug resistance to these groups of drugs. 
CA-MRSA pneumonia is frequently complicated by empyema, which requires drainage with tube thoracostomy and long-term management, as in the case of our patient who required tube drainage of the pyothorax and later had to undergo decortications of the lung due to the restrictive chest movement. There are few reports addressing the long-term recovery of patients with CA-MRSA necrotizing pneumonia.  Our patient after the subsidence of the pneumonia developed severe restrictive ventilatory defect with severely impaired gas transfer. The patient complained of severe dyspnea on exertion; thus, he needed to undergo pulmonary decortications and pulmonary rehabilitation. This case of a patient with CA-MRSA necrotizing pneumonia documents the natural course of the diseases, with prolonged pulmonary symptoms and hypoxemia requiring treatment, and highlights the fact that the clinician should consider the possibility of CA-MRSA in cases of severe pneumonia in their differential diagnosis in order to prevent mortality or long-term morbidity due to CA-MRSA pneumonia.
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